US20050191648A1 - Computer-directed assembly of a polynucleotide encoding a target polypeptide - Google Patents

Computer-directed assembly of a polynucleotide encoding a target polypeptide Download PDF

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US20050191648A1
US20050191648A1 US10/969,084 US96908404A US2005191648A1 US 20050191648 A1 US20050191648 A1 US 20050191648A1 US 96908404 A US96908404 A US 96908404A US 2005191648 A1 US2005191648 A1 US 2005191648A1
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polynucleotide
sequence
target
oligonucleotides
anneal
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Glen Evans
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Egea Biosciences LLC
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07KPEPTIDES
    • C07K1/00General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12NMICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N15/00Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
    • C12N15/09Recombinant DNA-technology
    • C12N15/10Processes for the isolation, preparation or purification of DNA or RNA
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12NMICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N15/00Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
    • C12N15/09Recombinant DNA-technology
    • C12N15/63Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
    • C12N15/66General methods for inserting a gene into a vector to form a recombinant vector using cleavage and ligation; Use of non-functional linkers or adaptors, e.g. linkers containing the sequence for a restriction endonuclease
    • GPHYSICS
    • G16INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16BBIOINFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR GENETIC OR PROTEIN-RELATED DATA PROCESSING IN COMPUTATIONAL MOLECULAR BIOLOGY
    • G16B30/00ICT specially adapted for sequence analysis involving nucleotides or amino acids
    • GPHYSICS
    • G16INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16BBIOINFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR GENETIC OR PROTEIN-RELATED DATA PROCESSING IN COMPUTATIONAL MOLECULAR BIOLOGY
    • G16B30/00ICT specially adapted for sequence analysis involving nucleotides or amino acids
    • G16B30/20Sequence assembly
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00274Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
    • B01J2219/00583Features relative to the processes being carried out
    • B01J2219/00603Making arrays on substantially continuous surfaces
    • B01J2219/00659Two-dimensional arrays
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00274Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
    • B01J2219/0068Means for controlling the apparatus of the process
    • B01J2219/00686Automatic
    • B01J2219/00689Automatic using computers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00274Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
    • B01J2219/0068Means for controlling the apparatus of the process
    • B01J2219/00695Synthesis control routines, e.g. using computer programs
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00274Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
    • B01J2219/0068Means for controlling the apparatus of the process
    • B01J2219/007Simulation or vitual synthesis
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00274Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
    • B01J2219/00718Type of compounds synthesised
    • B01J2219/0072Organic compounds
    • B01J2219/00722Nucleotides
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07BGENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B2200/00Indexing scheme relating to specific properties of organic compounds
    • C07B2200/11Compounds covalently bound to a solid support
    • CCHEMISTRY; METALLURGY
    • C40COMBINATORIAL TECHNOLOGY
    • C40BCOMBINATORIAL CHEMISTRY; LIBRARIES, e.g. CHEMICAL LIBRARIES
    • C40B40/00Libraries per se, e.g. arrays, mixtures
    • C40B40/04Libraries containing only organic compounds
    • C40B40/06Libraries containing nucleotides or polynucleotides, or derivatives thereof

Definitions

  • the present invention relates generally to the area of bioinformatics and more specifically to methods, algorithms and apparatus for computer directed polynucleotide assembly.
  • the invention further relates to the production of polypeptides encoded by polynucleotides assembled by the invention.
  • Enzymes, antibodies, receptors and ligands are polypeptides that have evolved by selective pressure to perform very specific biological functions within the milieu of a living organism.
  • the use of a polypeptide for specific technological applications may require the polypeptide to function in environments or on substrates for which it was not evolutionarily selected.
  • Polypeptides isolated from microorganisms that thrive in extreme environments provide ample evidence that these molecules are, in general, malleable with regard to structure and function.
  • the process for isolating a polypeptide from its native environment is expensive and time consuming.
  • new methods for synthetically evolving genetic material encoding a polypeptide possessing a desired activity are needed.
  • oligonucleotides covering the entire sequence to be synthesized are first allowed to anneal, and then the nicks are repaired with ligase. The fragment is then cloned directly, or cloned after amplification by the polymerase chain reaction (PCR). The polynucleotide is subsequently used for in vitro assembly into longer sequences.
  • the second general method for gene synthesis utilizes polymerase to fill in single-stranded gaps in the annealed pairs of oligonucleotides.
  • the present invention addresses the limitations in present recombinant nucleic acid manipulations by providing a fast, efficient means for generating a nucleic acid sequence, including entire genes, chromosomal segments, chromosomes and genomes. Because this approach is based on a completely synthetic approach, there are no limitations, such as the availability of existing nucleic acids, to hinder the construction of even very large segments of nucleic acid.
  • the invention provides a method of synthesizing a target polynucleotide sequence including; a) providing a target polynucleotide sequence; b), identifying at least one initiating polynucleotide present in the target polynucleotide which includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang and a 3′ overhang; c) identifying a second polynucleotide present in the target polynucleotide which is contiguous with the initiating polynucleotide and includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang, a 3′ overhang
  • the invention further provides a method of synthesizing a target polynucleotide including: a) providing a target polynucleotide sequence derived from a model sequence; b) identifying at least one initiating polynucleotide sequence present in the target polynucleotide sequence of a), wherein the initiating polynucleotide including: 1) a first, plus strand oligonucleotide; 2) a second plus strand oligonucleotide contiguous with the first plus strand oligonucleotide; and 3) a minus strand oligonucleotide including a first contiguous sequence which is at least partially complementary to the first plus strand oligonucleotide and second contiguous sequence which is at least partially complementary to the second plus strand oligonucleotide; c) annealing the first plus strand oligonucleotide and the second plus strand oligonucleotide to the
  • the invention provides a method a method for synthesizing a target polynucleotide, including; a) providing a target polynucleotide sequence derived from a model sequence; b) identifying at least one initiating polynucleotide present in the target polynucleotide which includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide; c) contacting the initiating polynucleotide under conditions suitable for primer annealing with a first oligonucleotide having partial complementarity to the 3′ portion of the plus strand of the initiating polynucleotide, and a second oligonucleotide having partial complementarity to the 3′ portion of the minus strand of the initiating polynucleotide; d) catalyzing under conditions suitable for primer extension: 1) polynucleotide synthesis from the 3′-hydroxyl of the
  • the invention further provides a method for isolating a target polypeptide encoded by a target polynucleotide generated by a method of the invention by; a) incorporating the target polynucleotide in an expression vector; b) introducing the expression vector into a suitable host cell; c) culturing the cell under conditions and for such time as to promote the expression of the target polypeptide encoded by the target polynucleotide; and d) isolating the target polypeptide.
  • the invention further provides a method of synthesizing a target polynucleotide including; a) providing a target polynucleotide sequence derived from a model sequence; b) chemically synthesizing a plurality of single-stranded oligonucleotides each of which is partially complementary to at least one oligonucleotide present in the plurality, where the sequence of the plurality of oligonucleotides is a contiguous sequence of the target polynucleotide; c) contacting the partially complementary oligonucleotides under conditions and for such time suitable for annealing, the contacting resulting in a plurality of partially double-stranded polynucleotides, where each double-stranded polynucleotide includes a 5′ overhang and a 3′ overhang; d) identifying at least one initiating polynucleotide derived from the model sequence present in the plurality of double-stranded polynucleo
  • the invention further provides a computer program, stored on a computer-readable medium, for generating a target polynucleotide sequence derived from a model sequence, the computer program comprising instructions for causing a computer system to: a) identify an initiating polynucleotide sequence contained in the target polynucleotide sequence; b) parse the target polynucleotide sequence into multiply distinct, partially complementary, oligonucleotides; c) control assembly of the target polynucleotide sequence by controlling the bi-directional extension of the initiating polynucleotide sequence by the sequential addition of partially complementary oligonucleotides resulting in a contiguous double-stranded polynucleotide.
  • the invention further provides a method for automated synthesis of a target polynucleotide sequence, including: a) providing the user with an opportunity to communicate a desired target polynucleotide sequence; b) allowing the user to transmit the desired target polynucleotide sequence to a server; c) providing the user with a unique designation; d) obtaining the transmitted target polynucleotide sequence provided by the user.
  • the invention further provides a method for automated synthesis of a polynucleotide sequence, including: a) providing a user with a mechanism for communicating a model polynucleotide sequence; b) optionally providing the user with an opportunity to communicate at least one desired modification to the model sequence if desired; c) allowing the user to transmit the model sequence and desired modification to a server; d) providing, user with a unique designation; e) obtaining the transmitted model sequence and optional desired modification provided by the user; f) inputting into a programmed computer, through an input device, data including at least a portion of the model polynucleotide sequence; g) determining, using the processor, the sequence of the model polynucleotide sequence containing the desired modification; h) further determining, using the processor, at least one initiating polynucleotide sequence present in the model polynucleotide sequence; i) selecting, using the processor, a model for synthesizing the modified model polynucleot
  • FIG. 1 depicts 96 well plates for of F (i.e., “forward” or “plus strand”) oligonucleotide synthesis, R (i.e., “reverse” or “minus strand”) oligonucleotide synthesis, and a T (i.e., “temperature”) plate for the annealing of F and T oligonucleotides.
  • F i.e., “forward” or “plus strand
  • R i.e., “reverse” or “minus strand”
  • T i.e., “temperature”
  • FIG. 2 depicts the oligonucleotide pooling plan where F oligonucleotides and R oligonucleotides are annealed to form a contiguous polynucleotide.
  • FIG. 3 depicts the schematic of assembly of a target polynucleotide sequence defining a gene, genome, set of genes or polypeptide sequence.
  • the sequence is designed by computer and used to generate a set of parsed oligonucleotide fragments covering the + and ⁇ strand of a target polynucleotide sequence encoding a target polypeptide.
  • FIG. 4 depicts a schematic of the polynuceotide synthesis modules.
  • a nanodispensing head with a plurality of valves will deposit synthesis chemicals in assembly vessels. Chemical distribution from the reagent reservoir can be controlled using a syringe pump. Underlying the reaction chambers is a set of assembly vessels linked to microchannels that will move fluids by microfluidics.
  • FIG. 5 depicts that oligonucleotide synthesis, oligonucleotide assembly by pooling and annealing, and ligation can be accomplished using microfluidic mixing.
  • FIG. 6 depicts the sequential pooling of oligonucleotides synthesized in arrays.
  • FIG. 7 depicts the pooling stage of the oligonucleotide components through the manifold assemblies resulting in the complete assembly of all oligonucleotides from the array.
  • FIG. 8 depicts an example of an assembly module comprising a complete set of pooling manifolds produced using microfabrication in a single unit.
  • Various configurations of the pooling manifold will allow assembly of increased numbers of well arrays of parsed component oligonucleotides.
  • FIG. 9 depicts the configuration for the assembly of oligonucleotides synthesized in a pre-defined array. Passage through the assembly device in the presence of DNA ligase and other appropriate buffer and chemical components will facilitate double stranded polynucleotide assembly.
  • FIG. 10 depicts an example of the pooling device design. Microgrooves or microfluidic channels are etched into the surface of the pooling device. The device provides a microreaction vessel at the junction of two channels for 1) mixing of the two streams, 2) controlled temperature maintenance or cycling a the site of the junction and 3) expulsion of the ligated mixture from the exit channel into the next set of pooling and ligation chambers.
  • FIG. 11 depicts the design of a polynucleotide synthesis platform comprising microwell plates addressed with a plurality of channels for microdispensing.
  • FIG. 12 depicts an example of a high capacity polynucleotide synthesis platform using high density microwell microplates capable of synthesizing in excess of 1536 component oligonucleotides per plate.
  • FIG. 13 depicts a polynucleotide assembly format using surface-bound oligonucleotide synthesis rather than soluble synthesis.
  • oligonucleotides are synthesized with a linker that allows attachment to a solid support.
  • FIG. 14 depicts a diagram of systematic polynucleotide assembly on a solid support.
  • a set of parsed component oligonucleotides are arranged in an array with a stabilizer oligonucletoide attached.
  • a set of ligation substrate oligonucleotides are placed in the solution and systematic assembly is carried out in the solid phase by sequential annealing, ligation and melting.
  • FIG. 15 depicts polynucleotide assembly using component oligonucleotides bound to a set of metal electrodes on a microelectronic chip. Each electrode can be controlled independently with respect to current and voltage.
  • FIG. 16 depicts generally a primer extension assembly method of the invention.
  • FIG. 17 provides a system diagram of the invention.
  • FIG. 18 depicts a perspective view of an instrument of the invention.
  • the complete sequence of complex genomes make large scale functional approaches to genetics possible.
  • the present invention outlines a novel approach to utilizing the results of genomic sequence information by computer-directed polynucleotide assembly based upon information available in databases such as the human genome database.
  • the present invention may be used to synthesize, assemble and select a novel, synthetic target polynucleotide sequence encoding a target polypeptide.
  • the target polynucleotide may encode a target polypeptide that exhibits enhanced or altered biological activity as compared to a model polypeptide encoded by a natural (wild-type) or model polynucleotide sequence.
  • standard assays may be used to survey the activity of an expressed target polypeptide.
  • the expressed target polypeptide can be assayed to determine its ability to carry out the function of the corresponding model polypeptide or to determine whether a target polypeptide exhibiting a new function has been produced.
  • the present invention provides a means for the synthetically evolving a model polypeptide by synthesizing, in a computer-directed fashion, polynucleotides encoding a target polypeptide derived from a model polypeptide.
  • the invention provides a method of synthesizing a target polynucleotide by providing a target polynucleotide sequence and identifying at least one initiating polynucleotide present in the target polynucleotide which includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang and a 3′ overhang.
  • a “target polynucleotide sequence” includes any nucleic acid sequence suitable for encoding a target polypeptide that can be synthesized by a method of the invention.
  • a target polynucleotide sequence can be used to generate a target polynucleotide using an apparatus capable of assembling nucleic sequences.
  • a target polynucleotide sequence is a linear segment of DNA having a double-stranded region; the segment may be of any length sufficiently long to be created by the hybridization of at least two oligonucleotides have complementary regions. It is contemplated that a target polynucleotide can be 100, 200, 300, 400, 800, 100, 1500, 200, 4000, 8000, 10000, 12000, 18,000, 20,000, 40,000, 80,000 or more base pairs in length.
  • the methods of the present invention will be able to create entire artificial genomes of lengths comparable to known bacterial, yeast, viral, mammalian, amphibian, reptilian, or avian genomes.
  • the target polynucleotide is a gene encoding a polypeptide of interest.
  • the target polynucleotide may further include non-coding elements such as origins of replication, telomeres, promoters, enhancers, transcription and translation start and stop signals, introns, exon splice sites, chromatin scaffold components and other regulatory sequences.
  • the target polynucleotide may comprises multiple genes, chromosomal segments, chromosomes and even entire genomes.
  • a polynucleotide of the invention may be derived from prokaryotic or eukaryotic sequences including bacterial, yeast, viral, mammalian, amphibian, reptilian, avian, plants, archebacteria and other DNA containing living organisms.
  • oligonucleotide is defined as a molecule comprised of two or more deoxyribonucleotides or ribonucleotides, preferably more than three. Its exact size will depend on many factors, such as the reaction temperature, salt concentration, the presence of denaturants such as formamide, and the degree of complementarity with the sequence to which the oligonucleotide is intended to hybridize.
  • nucleotide can refer to nucleotides present in either DNA or RNA and thus includes nucleotides which incorporate adenine, cytosine, guanine, thymine and uracil as base, the sugar moiety being deoxyribose or ribose. It will be appreciated however that other modified bases capable of base pairing with one of the conventional bases, adenine, cytosine, guanine, thymine and uracil, may be used in an oligonucleotide employed in the present invention. Such modified bases include for example 8-azaguanine and hypoxanthine. If desired the nucleotides may carry a label or marker so that on incorporation into a primer extension product, they augment the signal associated with the primer extension product, for example for capture on to solid phase.
  • a “plus strand” oligonucleotide by convention, includes a short, single-stranded DNA segment that starts with the 5′ end to the left as one reads the sequence.
  • a “minus strand” oligonucleotide includes a short, single-stranded DNA segment that starts with the 3′ end to the left as one reads the sequence.
  • Solid-phase synthesis techniques have been provided for the synthesis of several peptide sequences on, for example, a number of “pins” (See e.g., Geysen et al., J. Immun. Meth. (1987) 102:259-274, incorporated herein by reference in its entirety).
  • an “initiating polynucleotide sequence,” as used herein, is a sequence contained in a target polynucleotide sequence and identified by an algorithm of the invention.
  • An “initiating polynucleotide” is the physical embodiment of an initiating polynucleotide sequence. For ligation assembly of a target polynucleotide, an initiating polynucleotide begins assembly by providing an anchor for hybridization of subsequent polynucleotides contiguous with the initiating polynucleotide.
  • an initiating polynucleotide is partially double-stranded nucleic acid thereby providing single-stranded overhang(s) for annealing of a contiguous, double-stranded nucleic acid molecule.
  • an initiating polynucleotide begins assembly by providing a template for hybridization of subsequent oligonucleotides contiguous with the initiating polynucleotide.
  • an initiating polynucleotide can be partially double-stranded or fully double-stranded.
  • an initiating polynucleotide of the invention can be bound to a solid support for improved efficiency.
  • the solid phase allows for the efficient separation of the assembled target polynucleotide from other components of the reaction.
  • Different supports can be applied in the method.
  • supports can be magnetic latex beads or magnetic control pore glass beads that allows the desirable product from the reaction mixture to be magnetically separated. Binding the initiating polynucleotide to such beads can be accomplished by a variety of known methods, for example carbodiimide treatment (Gilham, Biochemistry 7:2809-2813 (1968); Mizutani and Tachbana, J. Chromatography 356:202-205 (1986); Wolf et al., Nucleic Acids Res. 15:2911-2926 (1987); Musso, Nucleic Acids Res. 15:5353-5372 (1987); Lund et al., Nucleic Acids Res. 16:10861-10880 (1988)).
  • the initiating polynucleotide attached to the solid phase can act as an anchor for the continued synthesis of the target polynucleotide.
  • Assembly can be accomplished by addition of contiguous polynucleotides together with ligase for ligation assembly or by addition of oligonucleotides together with polymerase for primer extension assembly. After the appropriate incubation time, unbound components of the method can be washed out and the reaction can be repeated again to improve the efficiency of template utilization. Alternatively, another set of polynucleotides or oligonucleotides can be added to continue the assembly.
  • Solid phase to be efficiently used for the synthesis, can contain pores with sufficient room for synthesis of the long nucleic acid molecules.
  • the solid phase can be composed of material that cannot non-specifically bind any undesired components of the reaction.
  • One way to solve the problem is to use control pore glass beads appropriate for long DNA molecules.
  • the initiating polynucleotide can be attached to the beads through a long connector. The role of the connector is to position the initiating polynucleotide from the surface of the solid support at a desirable distance.
  • the method of the invention further includes identifying a second polynucleotide sequence present in the target polynucleotide which is contiguous with the initiating polynucleotide and includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang, a 3′ overhang, or a 5′ overhang and a 3′ overhang, where at least one overhang of the second polynucleotide is complementary to at least one overhang of the initiating polynucleotide.
  • oligonucleotides having complementary regions will “anneal” (i.e., base pair) under the appropriate conditions, thereby producing a double-stranded region.
  • oligonucleotides In order to anneal (i.e., hybridize), oligonucleotides must be at least partially complementary.
  • the term “complementary to” is used herein in relation to nucleotides to mean a nucleotide that will base pair with another specific nucleotide.
  • adenosine triphosphate is complementary to uridine triphosphate or thymidine triphosphate
  • guanosine triphosphate is complementary to cytidine triphosphate.
  • a 5′ or 3′ “overhang” means a region on the 5′ or 3′, or 5′ and 3′, end of a polynucleotide that is single-stranded, i.e. not base paired.
  • An overhang provides a means for the subsequent annealing of a contiguous polynucleotide containing an overhang that is complementary to the overhang of the contiguous polynucleotide.
  • relatively stringent conditions For applications requiring high selectivity, one typically will desire to employ relatively stringent conditions to form the hybrids, e.g., one will select relatively low salt and/or high temperature conditions, such as provided by about 0.02 M to about 0.10 M NaCl at temperatures of about 50° C. to about 70° C. Such high stringency conditions tolerate little, if any, mismatch between the oligonucleotide and the template or target strand. It generally is appreciated that conditions can be rendered more stringent by the addition of increasing amounts of formamide.
  • lower stringency conditions may be used. Under these conditions, hybridization may occur even though the sequences of probe and target strand are not perfectly complementary, but are mismatched at one or more positions.
  • Conditions may be rendered less stringent by increasing salt concentration and decreasing temperature. For example, a medium stringency condition could be provided by about 0.1 to 0.25 M NaCl at temperatures of about 37° C. to about 55° C., while a low stringency condition could be provided by about 0.15 M to about 0.9 M salt, at temperatures ranging from about 20° C. to about 55° C.
  • hybridization conditions can be readily manipulated depending on the desired results.
  • oligonucleotides it will be advantageous to determine the hybridization of oligonucleotides by employing a label.
  • appropriate labels are known in the art, including fluorescent, radioactive, enzymatic or other ligands; such as avidin/biotin, which are capable of being detected.
  • enzyme tags colorimetric indicator substrates are known that can be employed to provide a means for detection visible to the human eye or spectrophotometrically to identify whether specific hybridization with complementary oligonucleotide has occurred.
  • At least one oligonucleotide of an initiating polynucleotide is adsorbed or otherwise affixed to a selected matrix or surface.
  • This fixed, single-stranded nucleic acid is then subjected to hybridization with the complementary oligonucleotides under desired conditions.
  • the selected conditions will also depend on the particular circumstances based on the particular criteria required (depending, for example, on the G+C content, type of target nucleic acid, source of nucleic acid, size of hybridization probe, etc.).
  • the hybridization may be detected, or even quantified, by means of the label.
  • the method of the invention further provides a third polynucleotide present in the target polynucleotide which is contiguous with the initiating sequence and provides a 5′ overhang, a 3′ overhang, or a 5′ overhang and a 3′ overhang, where at least one overhang of the third polynucleotide is complementary to at least one overhang of the initiating polynucleotide which is not complementary to an overhang of the second polynucleotide.
  • the method further provides contacting the initiating polynucleotide with the second polynucleotide and the third polynucleotide under conditions and for such time suitable for annealing, the contacting resulting in a contiguous double-stranded polynucleotide, resulting in the bi-directional extension of the initiating polynucleotide.
  • the annealed polynucleotides are optionally contacted with a ligase under conditions suitable for ligation.
  • the method discussed above is optionally repeated to sequentially add double-stranded polynucleotides to the extended initiating polynucleotide through repeated cycles of annealing and ligation.
  • a target polynucleotide sequence can be designed de novo or derived from a “model polynucleotide sequence”.
  • a “model polynucleotide sequence” includes any nucleic acid sequence that encodes a model polypeptide sequence.
  • a model polypeptide sequence provides a basis for designing a modified polynucleotide such that a target polynucleotide incorporating the desired modification is synthesized.
  • the present invention provides also provides methods that can be used to synthesize, de novo, polynucleotides that encode sets of genes, either naturally occurring genes expressed from natural or artificial promoter constructs or artificial genes derived from synthetic DNA sequences, which encode elements of biological systems that perform a specified function or attribution of an artificial organism as well as entire genomes.
  • the present invention provides the synthesis of a replication-competent, double-stranded polynucleotide, wherein the polynucleotide has an origin of replication, a first coding region and a first regulatory element directing the expression of the first coding region.
  • replication competent it is meant that the polynucleotide is capable of directing its own replication.
  • the polynucleotide will possess all the cis-acting signals required to facilitate its own synthesis.
  • the polynucleotide will be similar to a plasmid or a virus, such that once placed within a cell, it is capable of replication by a combination of the polynucleotide's and cellular functions.
  • a polynucleotide sequence defining a gene, genome, set of genes or protein sequence can be designed in a computer-assisted manner (discussed below) and used to generate a set of parsed oligonucleotides covering the plus (+) and minus ( ⁇ ) strand of the sequence.
  • a “parsed” means a target polynucleotide sequence has been delineated in a computer-assisted manner such that a series of contiguous oligonucleotide sequences are identified.
  • the oligonucleotide sequences are individually synthesized and used in a method of the invention to generate a target polynucleotide.
  • the length of an oligonucleotide is quite variable.
  • oligonucleotides used in the methods of the invention are between about 15 and 100 bases and more preferably between about 20 and 50 bases. Specific lengths include, but are not limited to 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64.
  • the overlap between the oligonucleotides having partial complementarity may be designed to be between 5 and 75 bases per oligonucleotide pair.
  • the oligonucleotides preferably are treated with polynucleotide kinase, for example, T4 polynucleotide kinase.
  • the kinasing can be performed prior to, or after, mixing of the oligonucleotides set or after, but before annealing.
  • the oligonucleotides are treated with an enzyme having a ligating function.
  • an enzyme having a ligating function For example, a DNA ligase typically will be employed for this function.
  • topoisomerase which does not require 5′ phosphorylation, is rapid and operates at room temperature, and may be used instead of ligase.
  • oligonucleotide array synthesizer For example, 50 base pair oligonucleotides overlapping by 25 bases can be synthesized by an oligonucleotide array synthesizer (OAS).
  • OAS oligonucleotide array synthesizer
  • a 5′ (+) strand set of oligonucleotides is synthesized in one 96-well plate and the second 3′ or ( ⁇ ) strand set is synthesized in a second 96-well microtiter plate.
  • Synthesis can be carried out using phosphoramidite chemistry modified to miniaturize the reaction size and generate small reaction volumes and yields in the range of 2 to 5 nmole.
  • Synthesis is done on controlled pore glass beads (CPGs), then the completed oligonucleotides are deblocked, deprotected and removed from the beads.
  • the oligonucleotides are lyophilized, re-suspended in water and 5′ phosphorylated using
  • the set of arrayed oligonucleotide sequences in the plate can be assembled using a mixed pooling strategy.
  • a mixed pooling strategy For example, systematic pooling of component oligonucleotides can be performed using a modified Beckman Biomek automated pipetting robot, or another automated lab workstation.
  • the fragments can be combined with buffer and enzyme (Taq I DNA ligase or Egea AssemblaseTM, for example). Pooling can be performed in microwell plates. After each step of pooling, the temperature is ramped to enable annealing and ligation, then additional pooling carried out.
  • Target polynucleotide assembly involves forming a set of intermediates.
  • a set of intermediates can include a plus strand oligonucleotide annealed to a minus strand oligonucleotide, as described above.
  • the annealed intermediate can be formed by providing a single plus strand oligonucleotide annealed to a single minus strand oligonucleotide.
  • two or more oligonucleotides may comprise the plus strand or the minus strand.
  • a polynucleotide e.g., an initiating polynucleotide
  • three or more oligonucleotides can be annealed.
  • a first plus strand oligonucleotide, a second plus strand oligonucleotide contiguous with the first plus strand oligonucleotide, and a minus strand oligonucleotide having a first contiguous sequence which is at least partially complementary to the first plus strand oligonucleotide and second contiguous sequence which is at least partially complementary to the second plus strand oligonucleotide can be annealed to form a partially double-stranded polynucleotide.
  • the polynucleotide can include a 5′ overhang, a 3′ overhang, or a 5′ overhang and a 3′ overhang.
  • the first plus strand oligonucleotide and second plus strand oligonucleotide are contiguous sequences such that they are ligatable.
  • the minus strand oligonucleotide is partially complementary to both plus strand oligonucleotides and acts as a “bridge” or “stabilizer” sequence by annealing to both oligonucleotides.
  • Subsequent polynucleotides comprised of more than two oligonucleotides annealed as previously described, can be used to assemble a target polynucleotide in a manner resulting in a contiguous double-stranded polynucleotide.
  • FIG. 3 An example of using two or more plus strand oligonucleotides to assemble a polynucleotide is shown in FIG. 3 .
  • Two of these oligonucleotides provide a ligation substrate joined by ligase and the third oligonucleotide is a stabilizer that brings together two specific sequences by annealing resulting in the formation of a part of the final polynucleotide construct.
  • This intermediate provides a substrate for DNA ligase which, through its nick sealing activity, joins the two 50-base pair oligonucleotides into a single 100 base single-stranded polynucleotide.
  • the products are assembled into increasingly larger polynucleotides.
  • sets of triplexes are systematically joined, ligated, and assembled.
  • Each step can be mediated by robotic pooling, ligation and thermal cycling to achieve annealing and denaturation.
  • the final step joins assembled pieces into a complete sequence representing all of the fragments in the array. Since the efficiency of yield at each step is less than 100%, the mass amount of completed product in the final mixture may be very small.
  • additional specific oligonucleotide primers usually 15 to 20 bases and complementary to the extreme ends of the assembly, can be annealed and PCR amplification carried out, thereby amplifying and purifying the final full-length product.
  • synthesis can utilize microdispensing piezioelectric or microsolenoid nanodispensors allowing very fast synthesis, much smaller reaction volumes and higher density plates as synthesis vessels.
  • the instrument will use up to 1536 well plates giving a very high capacity.
  • controlled pooling can be performed by a microfluidic manifold that will move individual oligonucleotides though microchannels and mix/ligate in a controlled way. This will obviate the need for robotic pipetting and increases speed and efficiency.
  • an apparatus that accomplishes a method of the invention will have a greater capability for simultaneous reactions giving an overall larger capacity for gene length.
  • target polynucleotide Once target polynucleotide have been synthesized using a method of the present invention, it may be necessary to screen the sequences for analysis of function.
  • chip-based DNA technologies Specifically contemplated by the present inventor are chip-based DNA technologies. Briefly, these techniques involve quantitative methods for analyzing large numbers of genes rapidly and accurately. By tagging genes with oligonucleotides or using fixed probe arrays, one can employ chip technology to segregate target molecules as high-density arrays and screen these molecules on the basis of hybridization.
  • the invention provides a method of synthesizing a target polynucleotide by providing a target polynucleotide sequence and identifying at least one initiating polynucleotide sequence present in the target polynucleotide sequence that includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a double-stranded polynucleotide.
  • the initiating polynucleotide is contacted under conditions suitable for primer annealing with a first oligonucleotide having partial complementarity to the 3′ portion of the plus strand of the initiating polynucleotide, and a second oligonucleotide having partial complementarity to the 3′ portion of the minus strand of the initiating polynucleotide.
  • Primer extension subsequently performed using polynucleotide synthesis from the 3′-hydroxyl of: 1) the plus strand of the initiating polynucleotide; 2) the annealed first oligonucleotide; 3) the minus strand of the initiating polynucleotide; and 4) the annealed second oligonucleotide.
  • the synthesis results in the initiating sequence being extended bi-directionally thereby forming a nascent extended initiating polynucleotide.
  • the extended initiating sequence can be further extended by repeated cycles of annealing and primer extension.
  • oligonucleotides can be used as building blocks to assemble polynucleotides through annealing and ligation reactions.
  • oligonucleotides can be used as primers to manufacture polynucleotides through annealing and primer extension reactions.
  • primer is used herein to refer to a binding element which comprises an oligonucleotide, whether occurring naturally as in a purified restriction digest or produced synthetically, which is capable of acting as a point of initiation of synthesis when placed under conditions in which synthesis of a primer extension product which is complementary to a nucleic acid strand is induced, i.e., in the presence of appropriate nucleotides and an agent for polymerization such as a DNA polymerase in an appropriate buffer (“buffer” includes pH, ionic strength, cofactors, etc.) and at a suitable temperature.
  • buffer includes pH, ionic strength, cofactors, etc.
  • the primer is preferably single stranded for maximum efficiency in amplification, but may alternatively be double stranded. If double stranded, the primer is first treated to separate its strands before being used to prepare extension products.
  • the primer is an oligodeoxyribonucleotide.
  • the primer must be sufficiently long to prime the synthesis of extension products in the presence of the agent for polymerization. The exact lengths of the primers will depend on many factors, including temperature and source of primer and use of the method. Primers having only short sequences capable of hybridization to the target nucleotide sequence generally require lower temperatures to form sufficiently stable hybrid complexes with the template.
  • the primers herein are selected to be “substantially” complementary to the different strands of each specific sequence to be amplified. This means that the primers must be sufficiently complementary to hybridize with their respective strands. Therefore, the primer sequence need not reflect the exact sequence of the template. Commonly, however, the primers have exact complementarity except with respect to analyses effected according to the method described in Nucleic Acids Research 17 (7) 2503-2516 (1989) or a corresponding method employing linear amplification or an amplification technique other than the polymerase chain reaction.
  • the agent for primer extension of an oligonucleotide may be any compound or system that will function to accomplish the synthesis of primer extension products, including enzymes. Suitable enzymes for this purpose include, for example, E. coli DNA Polymerase I, Klenow fragment of E. coli DNA polymerase I, T4 DNA polymerase, other available DNA polymerases, reverse transcriptase, and other enzymes, including thermostable enzymes.
  • thermostable enzyme refers to any enzyme that is stable to heat and is heat resistant and catalyses (facilitates) combination of the nucleotides in the proper manner to form the primer extension products which are complementary to each nucleic acid strand.
  • thermostable enzyme that may be employed in the process of the present invention is that which can be extracted and purified from Thermus aquaticus . Such an enzyme has a molecular weight of about 86,000-90,000 daltons.
  • Thermus aquaticus strain YT1 is available without restriction from the American Type Culture Collection, 12301 Parklawn Drive, Rockville, Md., U.S.A. as ATCC 25,104.
  • K. Kleppe et al in J. Mol. Biol., (1971), 56, 341-361 disclose a method for the amplification of a desired DNA sequence.
  • the method involves denaturation of a DNA duplex to form single strands.
  • the denaturation step is carried out in the presence of a sufficiently large excess of two nucleic acid primers that hybridize to regions adjacent to the desired DNA sequence.
  • DNA polymerase and a sufficient amount of each required nucleoside triphosphate are added whereby two molecules of the original duplex are obtained.
  • the above cycle of denaturation, primer addition and extension are repeated until the appropriate number of copies of the desired target polynucleotide is obtained.
  • the present invention further provides a method for the expression and isolation of a target polypeptide encoded by a target polynucleotide.
  • the method includes incorporating a target polynucleotide synthesized by a method of the invention into an expression vector; introducing the expression vector of into a suitable host cell; culturing the host cell under conditions and for such time as to promote the expression of the target polypeptide encoded by the target polynucleotide; and isolating the target polypeptide.
  • the invention can be used to modify certain functional, structural, or phylogenic features of a model polynucleotide encoding a model polypeptide resulting in an altered target polypeptide.
  • An input or model polynucleotide sequence encoding a model polypeptide can be electronically manipulated to determine a potential for an effect of an amino acid change (or variance) at a particular site or multiple sites in the model polypeptide.
  • a novel target polynucleotide sequence is assembled by a method of the invention such that the target polynucleotide encodes a target polypeptide possessing a characteristic different from that of the model polypeptide.
  • the methods of the invention may rely on the use of public sequence and structure databases. These databases become more robust as more and more sequences and structures are added.
  • Information regarding the amino acid sequence of a target polypeptide and the tertiary structure of the polypeptide can be used to synthesize oligonucleotides that can be assembled into a target polynucleotide encoding a target polypeptide.
  • a model polypeptide should have sufficient structural information to analyze the amino acids involved in the function of the polypeptide.
  • the structural information can be derived from x-ray crystallography, NMR, or some other technique for determining the structure of a protein at the amino acid or atomic level.
  • the sequence and structural information obtained from the model polypeptide can be used to generate a plurality of polynucleotides encoding a plurality of variant amino acid sequences that comprise a target polypeptide.
  • a model polypeptide can be selected based on overall sequence similarity to the target protein or based on the presence of a portion having sequence similarity to a portion of the target polypeptide.
  • a “polypeptide”, as used herein, is a polymer in which the monomers are alpha amino acids and are joined together through amide bonds.
  • Amino acids may be the L-optical isomer or the D-optical isomer.
  • Polypeptides are two or more amino acid monomers long and are often more than 20 amino acid monomers long. Standard abbreviations for amino acids are used (e.g., P for proline). These abbreviations are included in Stryer, Biochemistry, Third Ed., 1988, which is incorporated herein by reference for all purposes.
  • isolated refers to a polypeptide that constitutes the major component in a mixture of components, e.g., 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more by weight.
  • Isolated polypeptides typically are obtained by purification from an organism in which the polypeptide has been produced, although chemical synthesis is also possible. Method of polypeptide purification includes, for example, chromatography or immunoaffinity techniques.
  • Polypeptides of the invention may be detected by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis followed by Coomassie Blue-staining or Western blot analysis using monoclonal or polyclonal antibodies that have binding affinity for the polypeptide to be detected.
  • SDS sodium dodecyl sulphate
  • Coomassie Blue-staining or Western blot analysis using monoclonal or polyclonal antibodies that have binding affinity for the polypeptide to be detected.
  • a “chimeric polypeptide,” as used herein, is a polypeptide containing portions of amino acid sequence derived from two or more different proteins, or two or more regions of the same protein that are not normally contiguous.
  • a “ligand”, as used herein, is a molecule that is recognized by a receptor.
  • ligands that can be investigated by this invention include, but are not restricted to, agonists and antagonists for cell membrane receptors, toxins and venoms, viral epitopes, hormones, opiates, steroids, peptides, enzyme substrates, cofactors, drugs, lectins, sugars, oligonucleotides, nucleic acids, oligosaccharides, and proteins.
  • a “receptor”, as used herein, is a molecule that has an affinity for a ligand.
  • Receptors may be naturally occurring or manmade molecules. They can be employed in their unaltered state or as aggregates with other species. Receptors may be attached, covalently or noncovalently, to a binding member, either directly or via a specific binding substance.
  • Examples of receptors which can be employed by this invention include, but are not restricted to, antibodies, cell membrane receptors, monoclonal antibodies and antisera reactive with specific antigenic determinants, viruses, cells, drugs, polynucleotides, nucleic acids, peptides, cofactors, lectins, sugars, polysaccharides, cellular membranes, and organelles.
  • a “ligand receptor pair” is formed when two molecules have combined through molecular recognition to form a complex.
  • Microorganism receptors Determination of ligands that bind to microorganism receptors such as specific transport proteins or enzymes essential to survival of microorganisms would be a useful tool for discovering new classes of antibiotics. Of particular value would be antibiotics against opportunistic fungi, protozoa, and bacteria resistant to antibiotics in current use.
  • a receptor can comprise a binding site of an enzyme such as an enzyme responsible for cleaving a neurotransmitter; determination of ligands for this type of receptor to modulate the action of an enzyme that cleaves a neurotransmitter is useful in developing drugs that can be used in the treatment of disorders of neurotransmission.
  • an enzyme such as an enzyme responsible for cleaving a neurotransmitter
  • determination of ligands for this type of receptor to modulate the action of an enzyme that cleaves a neurotransmitter is useful in developing drugs that can be used in the treatment of disorders of neurotransmission.
  • the invention may be useful in investigating a receptor that comprises a ligand-binding site on an antibody molecule which combines with an epitope of an antigen of interest; determining a sequence that mimics an antigenic epitope may lead to the development of vaccines in which the immunogen is based on one or more of such sequences or lead to the development of related diagnostic agents or compounds useful in therapeutic treatments such as for autoimmune diseases (e.g., by blocking the binding of the “self” antibodies).
  • Polynucleotides Sequences of polynucleotides may be synthesized to establish DNA or RNA binding sequences that act as receptors for synthesized sequence.
  • Catalytic Polypeptides Polymers, preferably antibodies, which are capable of promoting a chemical reaction involving the conversion of one or more reactants to one or more products. Such polypeptides generally include a binding site specific for at least one reactant or reaction intermediate and an active functionality proximate to the binding site, which functionality is capable of chemically modifying the bound reactant. Catalytic polypeptides and others are described in, for example, PCT Publication-No. WO 90/05746, WO 90/05749, and WO 90/05785, which are incorporated herein by reference for all purposes.
  • Hormone receptors Identification of the ligands that bind with high affinity to a receptor such as the receptors for insulin and growth hormone is useful in the development of, for example, an oral replacement of the daily injections which diabetics must take to relieve the symptoms of diabetes or a replacement for growth hormone.
  • hormone receptors include the vasoconstrictive hormone receptors; determination of ligands for these receptors may lead to the development of drugs to control blood pressure.
  • Opiate receptors Determination of ligands which bind to the opiate receptors in the brain is useful in the development of less-addictive replacements for morphine and related drugs.
  • structure refers to the three dimensional arrangement of atoms in the protein.
  • Fusion refers to any measurable property of a protein. Examples of protein function include, but are not limited to, catalysis, binding to other proteins, binding to non-protein molecules (e.g., drugs), and isomerization between two or more structural forms.
  • Biologically relevant protein refers to any protein playing a role in the life of an organism.
  • the sequence of the model polypeptide is examined for matches to the entries in one or more databases of recognized domains, e.g., the PROSITE database domains (Bairoch, Nucl. Acids. Res. 24:217, 1997) or the pfam HMM database (Bateman et al., (2000) Nucl. Acids. Res. 28:263).
  • the PROSITE database is a compilation of two types of sequence signatures-profiles, typically representing whole protein domains, and patterns typically representing just the most highly conserved functional or structural aspects of protein domains.
  • the methods of the invention can be used to generate polypeptides containing polymorphisms that have an effect on a catalytic activity of a target polypeptide or a non-catalytic activity of the target polypeptide (e.g., structure, stability, binding to a second protein or polypeptide chain, binding to a nucleic acid molecule, binding to a small molecule, and binding to a macromolecule that is neither a protein nor a nucleic acid).
  • the invention provides a means for assembling any polynucleotide sequence encoding a target polypeptide such that the encoded polypeptide can be expressed and screened for a particular activity.
  • the operating temperature, operating pH, or any other characteristic of a polypeptide can be manipulated resulting in a polypeptide with a unique activity.
  • the methods of the invention can be used to identify amino acid substitutions that can be made to engineer the structure or function of a polypeptide of interest (e.g., to increase or decrease a selected activity or to add or remove a selective activity).
  • the methods of the invention can be used in the identification and analysis of candidate polymorphisms for polymorphism-specific targeting by pharmaceutical or diagnostic agents, for the identification and analysis of candidate polymorphisms for pharmacogenomic applications, and for experimental biochemical and structural analysis of pharmaceutical targets that exhibit amino acid polymorphism.
  • a library of target polynucleotides encoding a plurality of target polypeptides can be prepared by the present invention.
  • Host cells are transformed by artificial introduction of the vectors containing the target polynucleotide by inoculation under conditions conducive for such transformation.
  • the resultant libraries of transformed clones are then screened for clones which display activity for the polypeptide of interest in a phenotypic assay for activity.
  • a target polynucleotide of the invention can be incorporated (i.e., cloned) into an appropriate vector.
  • the target sequences encoding a target polypeptide of the invention may be inserted into a recombinant expression vector.
  • the term “recombinant expression vector” refers to a plasmid, virus, or other vehicle known in the art that has been manipulated by insertion or incorporation of the polynucleotide sequence encoding a target polypeptide of the invention.
  • the expression vector typically contains an origin of replication, a promoter, as well as specific genes that allow phenotypic selection of the transformed cells.
  • Vectors suitable for use in the present invention include, but are not limited to, the T7-based expression vector for expression in bacteria (Rosenberg et al., Gene, 56:125, 1987), the pMSXND-expression vector for expression in mammalian cells (Lee and Nathans, J. Biol. Chem., 263:3521, 1988), baculovirus-derived vectors for expression in insect cells, cauliflower mosaic virus, CaMV, tobacco mosaic virus, TMV.
  • any of a number of suitable transcription and translation elements including constitutive and inducible promoters, transcription enhancer elements, transcription terminators, etc. may be used in the expression vector (see, e.g., Bitter et al., Methods in Enzymology, 153:516-544, 1987). These elements are well known to one of skill in the art.
  • operably linked refers to functional linkage between the regulatory sequence and the polynucleotide sequence regulated by the regulatory sequence.
  • the operably linked regulatory sequence controls the expression of the product expressed by the polynucleotide sequence.
  • the functional linkage also includes an enhancer element.
  • Promoter means a nucleic acid regulatory sequence sufficient to direct transcription. Also included in the invention are those promoter elements that are sufficient to render promoter-dependent polynucleotide sequence expression controllable for cell-type specific, tissue specific, or inducible by external signals or agents; such elements may be located in the 5′ or 3′ regions of the native gene, or in the introns.
  • Gene expression or “polynucleotide sequence expression” means the process by which a nucleotide sequence undergoes successful transcription and translation such that detectable levels of the delivered nucleotide sequence are expressed in an amount and over a time period so that a functional biological effect is achieved.
  • yeast a number of vectors containing constitutive or inducible promoters may be used.
  • Current Protocols in Molecular Biology Vol. 2, Ed. Ausubel et al., Greene Publish. Assoc. & Wiley Interscience, Ch. 13, 1988; Grant et al., “Expression and Secretion Vectors for Yeast,” in Methods in Enzymology, Eds. Wu & Grossman, Acad. Press, N.Y., Vol. 153, pp. 516-544, 1987; Glover, DNA Cloning, Vol. II, IRL Press, Wash., D.C., Ch.
  • telomeres are repeated sequences found at chromosome ends and it has long been known that chromosomes with truncated ends are unstable, tend to fuse with other chromosomes and are otherwise lost during cell division.
  • telomeres interact with the nucleoprotein complex and the nuclear matrix.
  • One putative role for telomeres includes stabilizing chromosomes and shielding the ends from degradative enzyme.
  • telomeres Another possible role for telomeres is in replication. According to present doctrine, replication of DNA requires starts from short RNA primers annealed to the T-end of the template. The result of this mechanism is an “end replication problem” in which the region corresponding to the RNA primer is not replicated. Over many cell divisions, this will result in the progressive truncation of the chromosome. It is thought that telomeres may provide a buffer against this effect, at least until they are themselves eliminated by this effect. A further structure that may be included in target polynucleotide is a centromere.
  • the delivery of a nucleic acid in a cell may be identified in vitro or in vivo by including a marker in the expression construct.
  • the marker would result in an identifiable change to the transfected cell permitting easy identification of expression.
  • An expression vector of the invention can be used to transform a target cell.
  • transformation is meant a genetic change induced in a cell following incorporation of new DNA (i.e., DNA exogenous to the cell). Where the cell is a mammalian cell, the genetic change is generally achieved by introduction of the DNA into the genome of the cell.
  • transformed cell is meant a cell into which (or into an ancestor of which) has been introduced, by means of recombinant DNA techniques. Transformation of a host cell with recombinant DNA may be carried out by conventional techniques as are well known to those skilled in the art. Where the host is prokaryotic, such as E.
  • competent cells that are capable of DNA uptake can be prepared from cells harvested after exponential growth phase and subsequently treated by the CaCl 2 method by procedures well known in the art. Alternatively, MgCl 2 or RbCl can be used. Transformation can also be performed after forming a protoplast of the host cell or by electroporation.
  • a target polypeptide of the invention can be produced in prokaryotes by expression of nucleic acid encoding the polypeptide.
  • nucleic acid encoding the polypeptide.
  • These include, but are not limited to, microorganisms, such as bacteria transformed with recombinant bacteriophage DNA, plasmid DNA, or cosmid DNA expression vectors encoding a polypeptide of the invention.
  • the constructs can be expressed in E. coli in large scale for in vitro assays. Purification from bacteria is simplified when the sequences include tags for one-step purification by nickel-chelate chromatography. The construct can also contain a tag to simplify isolation of the polypeptide.
  • a polyhistidine tag of, e.g., six histidine residues, can be incorporated at the amino terminal end, or carboxy terminal end, of the protein.
  • the polyhistidine tag allows convenient isolation of the protein in a single step by nickel-chelate chromatography.
  • the target polypeptide of the invention can also be engineered to contain a cleavage site to aid in protein recovery.
  • the polypeptides of the invention can be expressed directly in a desired host cell for assays in situ.
  • Eukaryotic cells can also be cotransfected with DNA sequences encoding a polypeptide of the invention, and a second foreign DNA molecule encoding a selectable phenotype, such as the herpes simplex thymidine kinase gene.
  • Another method is to use a eukaryotic viral vector, such as simian virus 40 (SV40) or bovine papilloma virus, to transiently infect or transform eukaryotic cells and express the protein.
  • a eukaryotic viral vector such as simian virus 40 (SV40) or bovine papilloma virus
  • SV40 simian virus 40
  • bovine papilloma virus bovine papilloma virus
  • Eukaryotic systems and preferably mammalian expression systems, allow for proper post-translational modifications of expressed mammalian proteins to occur.
  • Eukaryotic cells that possess the cellular machinery for proper processing of the primary transcript, glycosylation, phosphorylation, and advantageously secretion of the gene product should be used as host cells for the expression of the polypeptide of the invention.
  • host cell lines may include, but are not limited to, CHO, VERO, BHK, HeLa, COS, MDCK, Jurkat, HEK-293, and WI38.
  • host cells can be transformed with the cDNA encoding a target polypeptide of the invention controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker.
  • expression control elements e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.
  • selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into their chromosomes and grow to form foci that, in turn, can be cloned and expanded into cell lines.
  • engineered cells may be allowed to grow for 1-2 days in an enriched media, and then are switched to a selective media.
  • a number of selection systems may be used, including, but not limited to, the herpes simplex virus thymidine kinase (Wigler et al., Cell, 11:223, 1977), hypoxanthine-guanine phosphoribosyltransferase (Szybalska & Szybalski, Proc. Natl. Acad. Sci.
  • adenine phosphoribosyltransferase genes can be employed in tk-, hgprt- or aprt-cells, respectively.
  • antimetabolite resistance can be used as the basis of selection for dhfr, which confers resistance to methotrexate (Wigler et al., Proc. Natl. Acad. Sci. USA, 77:3567, 1980; O'Hare et al., Proc. Natl. Acad. Sci.
  • gpt which confers resistance to mycophenolic acid
  • neo which confers resistance to the aminoglycoside G-4.18
  • hygro which confers resistance to hygromycin genes
  • trpB which allows cells to utilize indole in place of tryptophan
  • hisD which allows cells to utilize histinol in place of histidine
  • ODC ornithine decarboxylase
  • DFMO 2-(difluoromethyl)-DL-ornithine
  • Techniques for the isolation and purification of either microbially or eukaryotically expressed polypeptides of the invention may be by any conventional means, such as, for example, preparative chromatographic separations and immunological separations, such as those involving the use of monoclonal or polyclonal antibodies or antigen.
  • a target polynucleotide, or expression construct containing a target polynucleotide, may be entrapped in a liposome.
  • Liposomes are vesicular structures characterized by a phospholipid bilayer membrane and an inner aqueous medium. Multilarnellar liposomes have multiple lipid layers separated by aqueous medium and form spontaneously when phospholipids are suspended in an excess of aqueous solution. The lipid components undergo self-rearrangement before the formation of closed structures and entrap water and dissolved solutes between the lipid bilayers.
  • the liposome may be complexed with a hernagglutinating virus (HVJ).
  • HVJ hernagglutinating virus
  • the liposome may be complexed or employed in conjunction with nuclear non-histone chromosomal proteins (HMG-1).
  • the liposome may be complexed or employed in conjunction with both HVJ and HMG-1.
  • expression constructs have been successfully employed in transfer and expression of nucleic acid in vitro and in vivo, then they are applicable for the present invention.
  • a bacterial promoter is employed in the DNA construct, it also will be desirable to include within the liposome an appropriate bacterial polymerase.
  • the present invention describes methods for enabling the creation of a target polynucleotide based upon information only, i.e., without the requirement for existing genes, DNA molecules or genomes.
  • a virtual polynucleotide in the computer.
  • This polynucleotide consists of a string of DNA bases, G, A, T or C, comprising for example an entire artificial polynucleotide sequence in a linear string.
  • computer software is then used to parse the target sequence breaking it down into a set of overlapping oligonucleotides of specified length. This results in a set of shorter DNA sequences that overlap to cover the entire length of the target polynucleotide in overlapping sets.
  • a gene of 1000 bases pairs would be broken down into 20 100-mers where 10 of these comprise one strand and 10 of these comprise the other strand. They would be selected to overlap on each strand by 25 to 50 base pairs.
  • the degeneracy of the genetic code permits substantial freedom in the choice of codons for any particular amino acid sequence.
  • Transgenic organisms such as plants frequently prefer particular codons that, though they encode the same protein, may differ from the codons in the organism from which the gene was derived.
  • U.S. Pat. No. 5,380,831 to Adang et al. describes the creation of insect resistant transgenic plants that express the Bacillus thuringiensis (Bt) toxin gene.
  • the Bt crystal protein, an insect toxin is encoded by a full-length gene that is poorly expressed in transgenic plants.
  • a synthetic gene encoding the protein containing codons preferred in plants was substituted for the natural sequence.
  • the invention disclosed therein comprised a chemically synthesized gene encoding an insecticidal protein which is frequently equivalent to a native insecticidal protein of Bt.
  • the synthetic gene was designed to be expressed in plants at a level higher than a native Bt gene.
  • the hydropathic index of amino acids may be considered.
  • the importance of the hydropathic amino acid index in conferring interactive biologic function on a protein is generally understood in the art.
  • Each amino acid has been assigned a hydropathic index on the basis of their hydrophobicity and charge characteristics, these are: Isoleucine (+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine ( ⁇ 0.4); threonine (47); serine ( ⁇ 0.8); tryptophan ( ⁇ 0.9); tyrosine ( ⁇ 1.3); proline ( ⁇ 1.6); histidine ( ⁇ 3.2); glutamate ( ⁇ 3.5); glutamine ( ⁇ 3.5); aspartate ( ⁇ 3.5); asparagine ( ⁇ 3.5); lysine ( ⁇ 3.9); and arginine (45).
  • amino acids may be substituted by other amino acids having a similar hydropathic index or score and still result in a protein with similar biological activity, i.e., still obtain a biological functionally equivalent protein.
  • substitution of amino acids whose hydropathic indices are within ⁇ 2 is preferred, those which are within ⁇ I are particularly preferred, and those within ⁇ 0.5 are even more particularly preferred.
  • hydrophilicity values have been assigned to amino acid residues: arginine (+3.0); lysine (+3.0); aspartate (+3.0 ⁇ 1); glutarnate (+3.0 ⁇ 1); serine (+0.3); asparagine (+0.2); glutamine (+0.2); glycine (0); threonine (44); proline ( ⁇ 0.5 ⁇ 1); alanine (45); histidine ⁇ 0.5); cysteine ( ⁇ 1.0); methionine ( ⁇ 1.3); valine 1.5); leucine ( ⁇ 1.8); isoleucine ( ⁇ 1.8); tyrosine ( ⁇ 2.3); phenylalanine ( ⁇ 2.5); tryptophan ( ⁇ 3.4).
  • an amino acid can be substituted for another having a similar hydrophilicity value and still obtain a biologically equivalent and immunologically equivalent polypeptide.
  • substitution of amino acids whose hydrophilicity values are within ⁇ 2 is preferred, those that are within ⁇ 1 are particularly preferred, and those within ⁇ 0.5 are even more particularly preferred.
  • amino acid substitutions are generally based on the relative similarity of the amino acid side-chain substituents, for example, their hydrophobicity, hydrophilicity, charge, size, and the like.
  • Exemplary substitutions that take various of the foregoing characteristics into consideration are well known to those of skill in the art and include: arginine and lysine; glutarnate and aspartate; serine and threonine; glutamine and asparagine; and valine, leucine and isoleucine.
  • aspects of the invention may be implemented in hardware or software, or a combination of both.
  • the algorithms and processes of the invention are implemented in one or more computer programs executing on programmable computers each comprising at least one processor, at least one data storage system (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device.
  • Program code is applied to input data to perform the functions described herein and generate output information.
  • the output information is applied to one or more output devices, in known fashion.
  • Each program may be implemented in any desired computer language (including machine, assembly, high level procedural, or object oriented programming languages) to communicate with a computer system.
  • the language may be a compiled or interpreted language.
  • Each such computer program is preferably stored on a storage medium or device (e.g., ROM, CD-ROM, tape, or magnetic diskette) readable by a general or special purpose programmable computer, for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein.
  • a storage medium or device e.g., ROM, CD-ROM, tape, or magnetic diskette
  • the inventive system may also be considered to be implemented as a computer-readable storage medium, configured with a computer program, where the storage medium so configured causes a computer to operate in a specific and predefined manner to perform the functions described herein.
  • the invention provides a computer program, stored on a computer-readable medium, for generating a target polynucleotide sequence.
  • the computer program includes instructions for causing a computer system to: 1) identify an initiating polynucleotide sequence contained in the target polynucleotide sequence; 2) parse the target polynucleotide sequence into multiply distinct, partially complementary, oligonucleotides; and 3) control assembly of the target polynucleotide sequence by controlling the bi-directional extension of the initiating polynucleotide sequence by the sequential addition of partially complementary oligonucleotides resulting in a contiguous double-stranded polynucleotide.
  • the computer program will contain an algorithm for parsing the sequence of the target polynucleotide by generating a set of oligonucleotides corresponding to a polypeptide sequence.
  • the algorithm utilizes a polypeptide sequence to generate a DNA sequence using a specified codon table.
  • the algorithm then generates a set of parsed oligonucleotides corresponding to the (+) and ( ⁇ ) strands of the DNA sequence in the following manner:
  • Algorithms of the invention useful for assembly of a target polynucleotide can further be described as Perl script as set forth below.
  • ALGORITHM 1 provides a method for converting a protein sequence into a polynucleotide sequence using E.
  • ALGORITHM 2 provides a method for parsing a polynucleotide sequence into component forward and reverse oligonucleotides that can be reassembled into a complete target polynucleotide encoding a target polypeptide: #$oligoname is the identifier name for the list and for each component #oligonucleotide #$OL is the length of each component oligonucleotide #$Overlap is the length of the overlap in bases between each forward and each #reverse oligonucleotide #$sequence is the DNA sequence in bases #$seqlen is the length of the DNA sequence in bases #$bas is the individual base in a sequence #$forseq is the sequence of a forward oligonucleotide #$revseq is the sequence of a reverse oligonucleotide #$revcomp is the reverse complemented sequence of the gene #$oligonameF- [ ] is the list of parsed forward oligos #
  • the invention further provides a computer-assisted method for synthesizing a target polynucleotide encoding a target polypeptide derived from a model sequence using a programmed computer including a processor, an input device, and an output device, by inputting into the programmed computer, through the input device, data including at least a portion of the target polynucleotide sequence encoding a target polypeptide. Subsequently, the sequence of at least one initiating polynucleotide present in the target polynucleotide sequence is determined and a model for synthesizing the target polynucleotide sequence is derived.
  • the model is based on the position of the initiating sequence in the target polynucleotide sequence using overall sequence parameters necessary for expression of the target polypeptide in a biological system.
  • the information is outputted to an output device which provides the means for synthesizing and assembling to target polynucleotide.
  • any apparatus suitable for polynucleotide synthesis can be used in the present invention.
  • a nanodispensing head with up to 16 valves can be used to deposit synthesis chemicals in assembly vessels ( FIG. 4 ).
  • Chemicals can be controlled using a syringe pump from the reagent reservoir. Because of the speed and capability of the ink-jet dispensing system, synthesis can be made very small and very rapid.
  • Underlying the reaction chambers is a set of assembly vessels linked to microchannels that will move fluids by microfluidics. The configuration of the channels will pool pairs and triplexes of oligonucleotides systematically using, for example, a robotic device. However, pooling can be accomplished using fluidics and without moving parts.
  • oligonucleotide synthesis, oligonucleotide assembly by pooling and annealing, and ligation can be done using microfluidic mixing, resulting in the same set of critical triplex intermediates that serves as the substrate for annealing, ligation and oligonucleotide joining.
  • DNA ligase and other components can be placed in the buffer fluid moving through the instrument microchambers.
  • the pooling manifold can be produced from non-porous plastic and designed to control sequential pooling of oligonucleotides synthesized in arrays.
  • Oligonucleotide parsing from a gene sequence designed in the computer can be programmed for synthesis where (+) and ( ⁇ ) strands are placed in alternating wells of the array.
  • the 12 row sequences of the gene are directed into the pooling manifold that systematically pools three wells into reaction vessels forming the critical triplex structure.
  • four sets of triplexes are pooled into 2 sets of 6 oligonucleotide products, then 1 set of 12 oligonucleotide products.
  • Each row of the synthetic array is associated with a similar manifold resulting in the first stage of assembly of 8 sets of assembled oligonucleotides representing 12 oligonucleotides each.
  • the second manifold pooling stage is controlled by a single manifold that pools the 8 row assemblies into a single complete assembly. Passage of the oligonucleotide components through the two manifold assemblies (the first 8 and the second single) results in the complete assembly of all 96 oligonucleotides from the array.
  • the assembly module ( FIG. 8 ) of GenewriterTM can include a complete set of 7 pooling manifolds produced using microfabrication in a single plastic block that sits below the synthesis vessels. Various configurations of the pooling manifold will allow assembly of 96,384 or 1536 well arrays of parsed component oligonucleotides.
  • the initial configuration is designed for the assembly of 96 oligonucleotides synthesized in a pre-defined array, composed of 48 pairs of overlapping 50 mers. Passage through the assembly device in the presence of DNA ligase and other appropriate buffer and chemical components, and with appropriate temperature controls on the device, will assembly these into a single 2400base double stranded gene assembly ( FIG. 9 ).
  • the basic pooling device design can be made of PlexiglasTM or other type of co-polymer with microgrooves or microfluidic channels etched into the surface and with a temperature control element such as a Peltier circuit underlying the junction of the channels. This results in a microreaction vessel at the junction of two channels for 1) mixing of the two streams, 2) controlled temperature maintenance or cycling a the site of the junction and 3) expulsion of the ligated mixture from the exit channel into the next set of pooling and ligation chambers.
  • the assembly platform design can consist of 8 synthesis microwell plates in a 96 well configuration, addressed with 16 channels of microdispensing.
  • each plate below each plate is: 1) an evacuation manifold for removing synthesis components; and 2) an assembly manifold based on the schematic in FIG. 9 for assembling component oligonucleotides from each 96-well array.
  • FIG. 12 shows a higher capacity assembly format using 1536-well microplates and capable of synthesis of 1536 component oligonucleotides per plate.
  • Below each plate is: 1) an evacuation manifold for removing synthesis components; and 2) an assembly manifold assembly for assembling 1536 component oligonucleotides from each 1536-well array. Pooling and assembly strategies can be based on the concepts used for 96-well plates.
  • An alternative assembly format includes using surface-bound oligonucleotide synthesis rather than soluble synthesis on CPG glass beads ( FIG. 13 ).
  • oligonucleotides are synthesized with a hydrocarbon linker that allows attachment to a solid support.
  • the synthesized oligonucleotides are covalently attached to a solid support such that the stabilizer is attached and the two ligation substrates added to the overlying solution.
  • Ligation occurs as mediated by DNA ligase in the solution and increasing temperature above the Tm removes the linked oligonucleotides by thermal melting. As shown in FIG.
  • the systematic assembly on a solid support of a set of parsed component oligonucleotides can be arranged in an array with the set of stabilizer oligonucletoide attached.
  • the set of ligation substrate oligonucleotides are placed in the solution and, systematic assembly is carried out in the solid phase by sequential annealing, ligation and melting which moves the growing DNA molecules across the membrane surface.
  • FIG. 15 shows an additional alternative means for oligonucleotide assembly, by binding the component oligonucleotides to a set of metal electrodes on a microelectronic chip, where each electrode can be controlled independently with respect to current and voltage.
  • the array contains the set of minus strand oligonucleotides. Placing a positive change on the electrode will move by electrophoresis the component ligase substrate oligonucleotide onto the surface where annealing takes place. The presence of DNA ligase mediates covalent joining or ligation of the components. The electrode is then turned off or a negative charge is applied and the DNA molecule expulsed from the electrode.
  • next array element containing the next stabilizer oligonucleotide from the parsed set is turned on with a positive charge and a second annealing, joining and ligation with the next oligonucleotide in the set carried out.
  • Systematic and repetitive application of voltage control, annealing, ligation and denaturation will result in the movement of the growing chain across the surface as well as assembly of the components into a complete DNA molecule.
  • a desired sequence can be ordered by any means of communication available to a user wishing to order such a sequence.
  • a “user”, as used herein, is any entity capable of communicating a desired polynucleotide sequence to a server.
  • the sequence may be transmitted by any means of communication available to the user and receivable by a server.
  • the user can be provided with a unique designation such that the user can obtain information regarding the synthesis of the polynucleotide during synthesis.
  • the transmitted target polynucleotide sequence can be synthesized by any method set forth in the present invention.
  • the invention further provides a method for automated synthesis of a polynucleotide, by providing a user with a mechanism for communicating a model polynucleotide sequence and optionally providing the user with an opportunity to communicate at least one desired modification to the model sequence.
  • the invention envisions a user providing a model sequence and a desired modification to that sequence which results in the alteration of the model sequence. Any modification that alters the expression, function or activity of a target polynucleotide or encoded target polypeptide can be communicated by the user such that a modified polynucleotide or polypeptide is synthesized or expressed according to a method of the invention.
  • a model polynucleotide encoding a polypeptide normally expressed in a eukaryotic system can be altered such that the codons of the resulting target polynucleotide are conducive for expression of the polypeptide in a prokaryotic system.
  • the user can indicate a desired modified activity of a polypeptide encoded by a model polynucleotide.
  • the algorithms and methods of the present invention can be used to synthesize a target polynucleotide encoding a target polypeptide believed to have the desired modified activity.
  • the methods of the invention can be further utilized to express the target polypeptide and to screen for the desired activity. It is understood that the methods of the invention provide a means for synthetic evolution whereby any parameter of polynucleotide expression and/or polypeptide activity can be altered as desired.
  • the data including at least a portion of the model polynucleotide sequence is inputted into a programmed computer, through an input device.
  • the algorithms of the invention are used to determine the sequence of the model polynucleotide sequence containing the desired modification and resulting in a target polynucleotide containing the modification.
  • the processor and algorithms of the invention is used to identify at least one initiating polynucleotide sequence present in the polynucleotide sequence.
  • a target polynucleotide i.e., a modified model polynucleotide
  • a model polypeptide sequence or nucleic acid sequence is obtained and analyzed using a suitable DNA analysis package, such as, for example, MacVector or DNA Star. If the target protein will be expressed in a bacterial system, for example, the model sequence can be converted to a sequence encoding a polypeptide utilizing E. coli preferred codons (i.e., Type I, Type II or Type II codon preference).
  • E. coli preferred codons i.e., Type I, Type II or Type II codon preference.
  • the present invention provides the conversion programs Codon I, Codon II or Codon III.
  • a nucleic acid sequence of the invention can be designed to accommodate any codon preference of any prokaryotic or eucaryotic organism.
  • specific promoter, enhancer, replication or drug resistance sequences can be included in a synthetic nucleic acid sequence of the invention.
  • the length of the construction can be adjusted by padding to give a round number of bases based on about 25 to 100 bp synthesis.
  • the synthesis of sequences of about 25 to 100 bp in length can be manufactured and assembled using the array synthesizer-system and may be used without further purification. For example, two 96-well plates containing 100-mers could give a 9600 bp construction of a target sequence.
  • the oligonucleotides are parsed using ParseOligoTM, a proprietary computer program that optimizes nucleic acid sequence assembly. Optional steps in sequence assembly include identifying and eliminating sequences that may give rise to hairpins, repeats or other difficult sequences.
  • the parsed oligonucleotide list is transferred to the Synthesizer driver software. The individual oligonucleotides are pasted into the wells and oligonucleotide synthesis is accomplished.
  • oligonucleotide concentration is from 250 nM (250 ⁇ M/ml).
  • 50 base oligos give T m s from 75 to 85 degrees C., 6 to 10 od 260 , 11 to 15 nanomoles, 150 to 300 ⁇ g.
  • the PCR reaction includes:
  • Steps 2-7 of Table 1 Carry out pooling Step 2 mixing each successive well with the next. Add 1 ⁇ l of Taq1 ligase to each mixed well. Cycle once at 94 degrees for 30 sec; 52 degrees for 30 s; then 72 degrees for 10 minutes.
  • a final PCR amplification was then performed by taking 2 ul of final ligation mix and add to 20 ul of PCR mix containing 10 mM TRIS-HCl, pH 9.0, 2.2 mM MgCl 2 , 50 mM KCl, 0.2 mM each dNTP and 0.1% Triton X-100.
  • oligonucleotide concentration is from 250 nM (250 ⁇ M/ml).
  • 50 base oligos give T m s from 75 to 85 degrees C., 6 to 10 od 260 , 11 to 15 nanomoles, 150 to 300 ⁇ g. Resuspend in 50 to 100 ml of H 2 O to make 250 nM/ml.
  • the invention envisions using a robotic workstation to accomplish nucleic acid assembly.
  • two working plates containing forward and reverse oligonucleotides in a PCR mix at 2.5 mM are prepared and 1 ⁇ l of each oligo are added to 100 ⁇ l of PCR mix in a fresh microwell providing one plate of forward and one of reverse oligos in an array.
  • Cycling assembly is then initiated as follows according to the pooling scheme outlined in Table 1. In the present example, 96 cycles of assembly can be accomplished according to this scheme.
  • a PCR amplification is then performed by taking 2 ⁇ l of final reaction mix and adding it to 20 ⁇ l of a PCR mix comprising:
  • Outside primers are prepared by taking 1 ⁇ l of F1 and 1 ⁇ l of R96 at 250 mM (250 nm/ml-0.250 nmole/ml) and add to the 100 ⁇ l PCR reaction. This gives a final concentration of 2.5 ⁇ M each oligo.
  • 1 U Taq1 polymerase is subsequently added and the reaction is cycled for about 23 to 35 cycles under the following conditions: 94 degrees 30 s 50 degrees 30 s 72 degrees 60 s The reaction is subsequently extracted with phenol/chloroform, precipitated with ethanol and resuspend in 10 ml of dH 2 O for analysis on an agarose gel.
  • Equal amounts of forward and reverse oligos pairwise are added by taking 10 ⁇ l of forward and 10 ⁇ l of reverse oligo and mix in a new 96-well v-bottom plate.
  • This provides one array with sets of duplex oligonucleotides at 250 mM, according to pooling scheme Step 1 in Table 1.
  • An assembly plate was prepared by taking 2 ⁇ l of each oligomer pair and adding them to the plate containing 100 ⁇ l of ligation mix in each well. This gives an effective concentration of 2.5 ⁇ M or 2.5 nM/ml. About 20 ⁇ l of each well is transferred to a fresh microwell plate in addition to 11 ⁇ l of T4 polynucleotide kinase and 1 ⁇ l of 1 mM ATP. Each reaction will have 50 pmoles of oligonucleotide and 1 nmole ATP. Incubate at 37 degrees for 30 minutes.
  • Step 3 of pooling scheme is carried out and cycled according to the temperature scheme above.
  • Steps 4 and 5 of the pooling scheme are carried out and cycled according to the temperature scheme above.
  • Step 7 pooling scheme is carried out by pooling the remaining three wells.
  • outside primers are prepared by taking 1 ⁇ l of F1 and 1 ⁇ l of R96 at 250 mM (250 nm/ml-0.250 nmole/ml) and adding them to the 100 ⁇ l PCR reaction giving a final concentration of 2.5 uM for each oligo. Subsequentlly, 1 U of Taq1 polymerase is added and cycled for about 23 to 35 cycles under the following conditions: 94 degrees 30 s 50 degrees 30 s 72 degrees 60 s
  • the product is extracted with phenol/chloroform, precipitate with ethanol, resuspend in 10 ⁇ l of dH 2 O and analyzed on an agarose gel. TABLE 2 Pooling scheme for assembly using Taql polymerase (also topoisomerase II).
  • F-C8 ⁇ R-F6 denature, anneal, polymerase extension 33.
  • F-C9 ⁇ R-F5 denature, anneal, polymerase extension 34.
  • F-C10 ⁇ R-F4 denature, anneal, polymerase extension 35.
  • F-C11 ⁇ R-F3 denature, anneal, polymerase extension 36.
  • F-C12 ⁇ R-F2 denature, anneal, polymerase extension 37.
  • F-D1 ⁇ R-F1 denature, anneal, polymerase extension 38.
  • F-D2 ⁇ R-E12 denature, anneal, polymerase extension 39.
  • F-D3 ⁇ R-E11 denature, anneal, polymerase extension 40.
  • F-D4 ⁇ R-E10 denature, anneal, polymerase extension 41.
  • F-D5 ⁇ R-E9 denature, anneal, polymerase extension 42.
  • F-D6 ⁇ R-E8 denature, anneal, polymerase extension 43.
  • F-D7 ⁇ R-E7 denature, anneal, polymerase extension 44.
  • F-D8 ⁇ R-E6 denature, anneal, polymerase extension 45.
  • F-D9 ⁇ R-E5 denature, anneal, polymerase extension 46.
  • F-D10 ⁇ R-E4 denature, anneal, polymerase extension 47.
  • F-D11 ⁇ R-E3 denature, anneal, polymerase extension 48.
  • F-F4 ⁇ R-C10 denature, anneal, polymerase extension 65.
  • F-F5 ⁇ R-C9 denature, anneal, polymerase extension 66.
  • F-F6 ⁇ R-C8 denature, anneal, polymerase extension 67.
  • F-F7 ⁇ R-C7 denature, anneal, polymerase extension 68.
  • F-F8 ⁇ R-C6 denature, anneal, polymerase extension 69.
  • F-F9 ⁇ R-C5 denature, anneal, polymerase extension 70.
  • F-F10 ⁇ R-C4 denature, anneal, polymerase extension 71.
  • F-F11 ⁇ R-C3 denature, anneal, polymerase extension 72.
  • F-F12 ⁇ R-C2 denature, anneal, polymerase extension 73.
  • F-G1 ⁇ R-C1 denature, anneal, polymerase extension 74.
  • F-G2 ⁇ R-B12 denature, anneal, polymerase extension 75.
  • F-G3 ⁇ R-B11 denature, anneal, polymerase extension 76.
  • F-G4 ⁇ R-B10 denature, anneal, polymerase extension 77.
  • F-G5 ⁇ R-B9 denature, anneal, polymerase extension 78.
  • F-G6 ⁇ R-B8 denature, anneal, polymerase extension 79.
  • F-G7 ⁇ R-B7 denature, anneal, polymerase extension 80.
  • F-G8 ⁇ R-B6 denature, anneal, polymerase extension 81.
  • F-G9 ⁇ R-B5 denature, anneal, polymerase extension 82.
  • F-G10 ⁇ R-B4 denature, anneal, polymerase extension 83.
  • F-G11 ⁇ R-B3 denature, anneal, polymerase extension 84.
  • F-G12 ⁇ R-B2 denature, anneal, polymerase extension 85.
  • F-H1 ⁇ R-B1 denature, anneal, polymerase extension 86.
  • F-H2 ⁇ R-A12 denature, anneal, polymerase extension 87.
  • F-H3 ⁇ R-A11 denature, anneal, polymerase extension 88.
  • F-H4 ⁇ R-A10 denature, anneal, polymerase extension 89.
  • F-H5 ⁇ R-A9 denature, anneal, polymerase extension 90.
  • F-H6 ⁇ R-A8 denature, anneal, polymerase extension 91.
  • F-H7 ⁇ R-A7 denature, anneal, polymerase extension 92.
  • F-H8 ⁇ R-A6 denature, anneal, polymerase extension 93.
  • F-H9 ⁇ R-A5 denature, anneal, polymerase extension 94.
  • F-H10 ⁇ R-A4 denature, anneal, polymerase extension 95.
  • F-H11 ⁇ R-A3 denature, anneal, polymerase extension 96.
  • F-H12 ⁇ R-A2 denature, anneal, polymerase extension Assembly of Nucleic Acid Molecules
  • nucleic acid molecules listed in Table 4 have been produced using the methods described herein. The features and characteristics of each nucleic acid molecule is also described in Table 4.
  • the plasmid comprises 192 oligonucleotides (two sets of 96 overlapping 50 mers; 25 bp overlap).
  • the plasmid is essentially pUC containing kanamycin resistance instead of ampicillin resistance.
  • the synthetic plasmid also contains lux A and B genes from the Vibrio fisheri bacterial luciferase gene.
  • the SynPuc19 plasmid is 2700 bp in length comprising a sequence essentially identical to pUC19 only shortened to precisely 2700 bp. Two sets of 96 50 mers were used to assemble the plasmid.
  • the Synlux4 pUC19 plasmid was shortened and luxA gene was added. 54 100-mer oligonucleotides comprising two sets of 27 oligonucleotides were used to assemble the plasmid.
  • the miniQE10 plasmid comprising 2400 bp was assembled using 48 50 mer oligonucleotides.
  • MiniQE10 is an expression plasmid containing a 6 ⁇ His tag and bacterial promoter for high-level polypeptide expression. MiniQE10 was assembled and synthesized using the Taq1 polymerase amplification method of the invention.
  • the microQE plasmid is a minimal plasmid containing only an ampicillin gene, an origin of replication and a linker of pQE plasmids.
  • MicroQE was assembled using either combinatoric ligation with 24 50-mers or with one tube PCR amplification.
  • the SynFib1, SynFibB and SynFibG nucleic acid sequences are synthetic human fibrinogens manufactured using E. coli codons to optimize expression in a prokaryotic expression system. TABLE 4 Synthetic nucleic acid molecules produced using the methods of the invention.
  • Synthetic Plasmid 4800 192 50 circular F1-F96 SynPUC/19 2700 192 50 circular F01-F96 SynLux/4 2700 54 100 circular F1-27 MiniQE10 2400 48 50 circular MicroQE 1200 24 50 circular MQEF-1,24 Synfib1 1850 75 50 linear SFAF1-37 pQE25 2400 96 25 circular F1-F48 SynFibB 1500 60 59 50 mers linear FibbF1-30 1 25 mer SynFibG 1350 54 53 50 mers linear FibgF1-27 1 25 mer

Abstract

The present invention outlines a novel approach to utilizing the results of genomic sequence information by computer-directed polynucleotide assembly based upon information available in databases such as the human genome database. Specifically, the present invention may be used to select, synthesize and assemble a novel, synthetic target polynucleotide sequence encoding a target polypeptide. The target polynucleotide may encode a target polypeptide that exhibits enhanced or altered biological activity as compared to a model polypeptide encoded by a natural (wild-type) or model polynucleotide sequence.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • This application claims the benefit of, U.S. patent application Ser. No. 10/052,582 filed 18 Jan. 2002, which claims the benefit of U.S. Provisional Application No. 60/262,693, filed 19 Jan. 200. Each of the above referenced applications are incorporated herein by reference in their entirety.
  • TECHNICAL FIELD
  • The present invention relates generally to the area of bioinformatics and more specifically to methods, algorithms and apparatus for computer directed polynucleotide assembly. The invention further relates to the production of polypeptides encoded by polynucleotides assembled by the invention.
  • BACKGROUND
  • Enzymes, antibodies, receptors and ligands are polypeptides that have evolved by selective pressure to perform very specific biological functions within the milieu of a living organism. The use of a polypeptide for specific technological applications may require the polypeptide to function in environments or on substrates for which it was not evolutionarily selected. Polypeptides isolated from microorganisms that thrive in extreme environments provide ample evidence that these molecules are, in general, malleable with regard to structure and function. However, the process for isolating a polypeptide from its native environment is expensive and time consuming. Thus, new methods for synthetically evolving genetic material encoding a polypeptide possessing a desired activity are needed.
  • There are two ways to obtain genetic material for genetic engineering manipulations: (1) isolation and purification of a polynucleotide in the form of DNA or RNA from natural sources or (2) the synthesis of a polynucleotide using various chemical-enzymatic approaches. The former approach is limited to naturally-occurring sequences that do not easily lend themselves to specific modification. The latter approach is much more complicated and labor-intensive. However, the chemical-enzymatic approach has many attractive features including the possibility of preparing, without any significant limitations, any desirable polynucleotide sequence.
  • Two general methods currently exist for the synthetic assembly of oligonucleotides into long polynucleotide fragments. First, oligonucleotides covering the entire sequence to be synthesized are first allowed to anneal, and then the nicks are repaired with ligase. The fragment is then cloned directly, or cloned after amplification by the polymerase chain reaction (PCR). The polynucleotide is subsequently used for in vitro assembly into longer sequences. The second general method for gene synthesis utilizes polymerase to fill in single-stranded gaps in the annealed pairs of oligonucleotides. After the polymerase reaction, single-stranded regions of oligonucleotides become double-stranded, and after digestion with restriction endonuclease, can be cloned directly or used for further assembly of longer sequences by ligating different double-stranded fragments. Typically, subsequent to the polymerase reaction, each segment must be cloned which significantly delays the synthesis of long DNA fragments and greatly decreases the efficiency of this approach.
  • The creation of entirely novel polynucleotides, or the substantial modification of existing polynucleotides, is extremely time consuming, expensive, requires complex and multiple steps, and in some cases is impossible. Therefore, there exists a great need for an efficient means to assemble synthetic polynucleotides of any desired sequence. Such a method could be universally applied. For example, the method could be used to efficiently make an array of polynucleotides having specific substitutions in a known sequence that is expressed and screened for improved function. The present invention satisfies these needs by providing efficient and powerful methods and compositions for the synthesis of a target polynucleotide encoding a target polypeptide.
  • SUMMARY
  • The present invention addresses the limitations in present recombinant nucleic acid manipulations by providing a fast, efficient means for generating a nucleic acid sequence, including entire genes, chromosomal segments, chromosomes and genomes. Because this approach is based on a completely synthetic approach, there are no limitations, such as the availability of existing nucleic acids, to hinder the construction of even very large segments of nucleic acid.
  • In one embodiment, the invention provides a method of synthesizing a target polynucleotide sequence including; a) providing a target polynucleotide sequence; b), identifying at least one initiating polynucleotide present in the target polynucleotide which includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang and a 3′ overhang; c) identifying a second polynucleotide present in the target polynucleotide which is contiguous with the initiating polynucleotide and includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang, a 3′ overhang, or a 5′ overhang and a 3′ overhang, where at least one overhang of the second polynucleotide is complementary to at least one overhang of the initiating polynucleotide; d) identifying a third polynucleotide present in the target polynucleotide which is contiguous with the initiating sequence and includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang, a 3′ overhang, or a 5′ overhang and a 3′ overhang, where at least one overhang of the third polynucleotide is complementary to at least one overhang of the initiating polynucleotide which is not complementary to an overhang of the second polynucleotide; e) contacting the initiating polynucleotide with the second polynucleotide and the third polynucleotide under conditions and for such time suitable for annealing, the contacting resulting in a contiguous double-stranded polynucleotide, resulting in the bi-directional extension of the initiating polynucleotide; f) in the absence of primer extension, optionally contacting the mixture of e) with a ligase under conditions suitable for ligation; and g) optionally repeating b) through f) to sequentially add double-stranded polynucleotides to the extended initiating polynucleotide through repeated cycles of annealing and ligation, whereby a target polynucleotide is synthesized.
  • The invention further provides a method of synthesizing a target polynucleotide including: a) providing a target polynucleotide sequence derived from a model sequence; b) identifying at least one initiating polynucleotide sequence present in the target polynucleotide sequence of a), wherein the initiating polynucleotide including: 1) a first, plus strand oligonucleotide; 2) a second plus strand oligonucleotide contiguous with the first plus strand oligonucleotide; and 3) a minus strand oligonucleotide including a first contiguous sequence which is at least partially complementary to the first plus strand oligonucleotide and second contiguous sequence which is at least partially complementary to the second plus strand oligonucleotide; c) annealing the first plus strand oligonucleotide and the second plus strand oligonucleotide to the minus strand oligonucleotide of b) resulting in a partially double-stranded initiating polynucleotide including a 5′ overhang and a 3′ overhang; d) identifying a second polynucleotide sequence present in the target polynucleotide sequence of a), wherein the second polynucleotide sequence is contiguous with the initiating polynucleotide sequence and includes: 1) a first plus strand oligonucleotide; 2) a second plus strand oligonucleotide contiguous with the first plus strand oligonucleotide; and 3) a minus strand oligonucleotide comprising a first contiguous sequence which is at least partially complementary to the first plus strand oligonucleotide and second contiguous sequence which is at least partially complementary to the second plus strand oligonucleotide; e) annealing the first plus strand oligonucleotide and the second plus strand oligonucleotide to the minus strand oligonucleotide of d) resulting in a partially double-stranded second polynucleotide, wherein at least one overhang of the second polynucleotide is complementary to at least one overhang of the initiating polynucleotide; f) identifying a third polynucleotide present in the target polynucleotide of a), wherein the third polynucleotide is contiguous with the initiating sequence and comprises: 1) a first plus strand oligonucleotide; 2) a second plus strand oligonucleotide contiguous with the first plus strand oligonucleotide; and 3) a minus strand oligonucleotide comprising a first contiguous sequence which is at least partially complementary to the first plus strand oligonucleotide and second contiguous sequence which is at least partially complementary to the second plus strand oligonucleotide; g) annealing the first plus strand oligonucleotide and the second plus strand oligonucleotide to the minus strand oligonucleotide of f) resulting in a partially double-stranded second polynucleotide, wherein at least one overhang of the third polynucleotide is complementary to at least one overhang of the initiating polynucleotide and not complementary to an overhang of the second polynucleotide; h) contacting the initiating polynucleotide of c) with the second polynucleotide of e) and the third polynucleotide of g) under conditions and for such time suitable for annealing, the contacting resulting in a contiguous double-stranded polynucleotide, wherein the initiating sequence is extended-bi-directionally; i) in the absence of primer extension, optionally contacting the mixture of h) with a ligase under conditions suitable for ligation; and j) optionally repeating b) through i) to sequentially add double-stranded polynucleotides to the extended initiating polynucleotide through repeated cycles of annealing and ligation, whereby a target polynucleotide, is synthesized.
  • In another embodiment, the invention provides a method a method for synthesizing a target polynucleotide, including; a) providing a target polynucleotide sequence derived from a model sequence; b) identifying at least one initiating polynucleotide present in the target polynucleotide which includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide; c) contacting the initiating polynucleotide under conditions suitable for primer annealing with a first oligonucleotide having partial complementarity to the 3′ portion of the plus strand of the initiating polynucleotide, and a second oligonucleotide having partial complementarity to the 3′ portion of the minus strand of the initiating polynucleotide; d) catalyzing under conditions suitable for primer extension: 1) polynucleotide synthesis from the 3′-hydroxyl of the plus strand of the initiating polynucleotide; 2) polynucleotide synthesis from the 3′-hydroxyl of the annealed first oligonucleotide; 3) polynucleotide synthesis from the 3′-hydroxyl of the minus strand of the initiating polynucleotide; and 4) polynucleotide synthesis from the 3′-hydroxyl of the annealed second oligonucleotide, resulting in the bi-directional extension of the initiating sequence thereby forming a nascent extended initiating polynucleotide; e) contacting the extended initiating polynucleotide of d) under conditions suitable for primer annealing with a third oligonucleotide having partial complementarity to the 3′ portion of the plus strand of the extended initiating polynucleotide, and a fourth oligonucleotide having partial complementarity to the 3′ portion of the minus strand of the extended initiating polynucleotide; f) catalyzing under conditions suitable for primer extension: 1) polynucleotide synthesis from the 3′-hydroxyl of the plus strand of the extended initiating polynucleotide; 2) polynucleotide synthesis from the 3′-hydroxyl of the annealed third oligonucleotide; 3) polynucleotide synthesis from the 3′-hydroxyl of the minus strand of the extended initiating polynucleotide; and 4) polynucleotide synthesis from the 3′-hydroxyl of the annealed fourth oligonucleotide, resulting in the bi-directional extension of the initiating sequence thereby forming a nascent extended initiating polynucleotide; and g) optionally repeating e) through f) as desired, resulting in formation of the target polynucleotide sequence.
  • The invention further provides a method for isolating a target polypeptide encoded by a target polynucleotide generated by a method of the invention by; a) incorporating the target polynucleotide in an expression vector; b) introducing the expression vector into a suitable host cell; c) culturing the cell under conditions and for such time as to promote the expression of the target polypeptide encoded by the target polynucleotide; and d) isolating the target polypeptide.
  • The invention further provides a method of synthesizing a target polynucleotide including; a) providing a target polynucleotide sequence derived from a model sequence; b) chemically synthesizing a plurality of single-stranded oligonucleotides each of which is partially complementary to at least one oligonucleotide present in the plurality, where the sequence of the plurality of oligonucleotides is a contiguous sequence of the target polynucleotide; c) contacting the partially complementary oligonucleotides under conditions and for such time suitable for annealing, the contacting resulting in a plurality of partially double-stranded polynucleotides, where each double-stranded polynucleotide includes a 5′ overhang and a 3′ overhang; d) identifying at least one initiating polynucleotide derived from the model sequence present in the plurality of double-stranded polynucleotides; e) in the absence of primer extension, subjecting a mixture including the initiating polynucleotide and 1) a double-stranded polynucleotide that will anneal to the 5′ portion of said initiating and sequence; 2) a double-stranded polynucleotide that will anneal to the 3′ portion of the initiating polynucleotide; and 3) a DNA ligase under conditions suitable for annealing and ligation, wherein the initiating polynucleotide is extended bi-directionally; f) sequentially annealing double-stranded polynucleotides to the extended initiating polynucleotide through repeated cycles of annealing, whereby the target polynucleotide is produced.
  • The invention further provides a computer program, stored on a computer-readable medium, for generating a target polynucleotide sequence derived from a model sequence, the computer program comprising instructions for causing a computer system to: a) identify an initiating polynucleotide sequence contained in the target polynucleotide sequence; b) parse the target polynucleotide sequence into multiply distinct, partially complementary, oligonucleotides; c) control assembly of the target polynucleotide sequence by controlling the bi-directional extension of the initiating polynucleotide sequence by the sequential addition of partially complementary oligonucleotides resulting in a contiguous double-stranded polynucleotide.
  • The invention further provides a method for automated synthesis of a target polynucleotide sequence, including: a) providing the user with an opportunity to communicate a desired target polynucleotide sequence; b) allowing the user to transmit the desired target polynucleotide sequence to a server; c) providing the user with a unique designation; d) obtaining the transmitted target polynucleotide sequence provided by the user.
  • The invention further provides a method for automated synthesis of a polynucleotide sequence, including: a) providing a user with a mechanism for communicating a model polynucleotide sequence; b) optionally providing the user with an opportunity to communicate at least one desired modification to the model sequence if desired; c) allowing the user to transmit the model sequence and desired modification to a server; d) providing, user with a unique designation; e) obtaining the transmitted model sequence and optional desired modification provided by the user; f) inputting into a programmed computer, through an input device, data including at least a portion of the model polynucleotide sequence; g) determining, using the processor, the sequence of the model polynucleotide sequence containing the desired modification; h) further determining, using the processor, at least one initiating polynucleotide sequence present in the model polynucleotide sequence; i) selecting, using the processor, a model for synthesizing the modified model polynucleotide sequence based on the position of the initiating sequence in the model polynucleotide sequence; and j) outputting, to the output device, the results of the at least one determination.
  • Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. For example, the one letter and three letter abbreviations for amino acids and the one-letter abbreviations for nucleotides are commonly understood. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In addition, the materials, methods and examples are illustrative only and not intended to be limiting. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.
  • The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
  • DESCRIPTION OF DRAWINGS
  • Like reference symbols in the various drawings indicate like elements.
  • FIG. 1 depicts 96 well plates for of F (i.e., “forward” or “plus strand”) oligonucleotide synthesis, R (i.e., “reverse” or “minus strand”) oligonucleotide synthesis, and a T (i.e., “temperature”) plate for the annealing of F and T oligonucleotides.
  • FIG. 2 depicts the oligonucleotide pooling plan where F oligonucleotides and R oligonucleotides are annealed to form a contiguous polynucleotide.
  • FIG. 3 depicts the schematic of assembly of a target polynucleotide sequence defining a gene, genome, set of genes or polypeptide sequence. The sequence is designed by computer and used to generate a set of parsed oligonucleotide fragments covering the + and − strand of a target polynucleotide sequence encoding a target polypeptide.
  • FIG. 4 depicts a schematic of the polynuceotide synthesis modules. A nanodispensing head with a plurality of valves will deposit synthesis chemicals in assembly vessels. Chemical distribution from the reagent reservoir can be controlled using a syringe pump. Underlying the reaction chambers is a set of assembly vessels linked to microchannels that will move fluids by microfluidics.
  • FIG. 5 depicts that oligonucleotide synthesis, oligonucleotide assembly by pooling and annealing, and ligation can be accomplished using microfluidic mixing.
  • FIG. 6 depicts the sequential pooling of oligonucleotides synthesized in arrays.
  • FIG. 7 depicts the pooling stage of the oligonucleotide components through the manifold assemblies resulting in the complete assembly of all oligonucleotides from the array.
  • FIG. 8 depicts an example of an assembly module comprising a complete set of pooling manifolds produced using microfabrication in a single unit. Various configurations of the pooling manifold will allow assembly of increased numbers of well arrays of parsed component oligonucleotides.
  • FIG. 9 depicts the configuration for the assembly of oligonucleotides synthesized in a pre-defined array. Passage through the assembly device in the presence of DNA ligase and other appropriate buffer and chemical components will facilitate double stranded polynucleotide assembly.
  • FIG. 10 depicts an example of the pooling device design. Microgrooves or microfluidic channels are etched into the surface of the pooling device. The device provides a microreaction vessel at the junction of two channels for 1) mixing of the two streams, 2) controlled temperature maintenance or cycling a the site of the junction and 3) expulsion of the ligated mixture from the exit channel into the next set of pooling and ligation chambers.
  • FIG. 11 depicts the design of a polynucleotide synthesis platform comprising microwell plates addressed with a plurality of channels for microdispensing.
  • FIG. 12 depicts an example of a high capacity polynucleotide synthesis platform using high density microwell microplates capable of synthesizing in excess of 1536 component oligonucleotides per plate.
  • FIG. 13 depicts a polynucleotide assembly format using surface-bound oligonucleotide synthesis rather than soluble synthesis. In this configuration, oligonucleotides are synthesized with a linker that allows attachment to a solid support.
  • FIG. 14 depicts a diagram of systematic polynucleotide assembly on a solid support. A set of parsed component oligonucleotides are arranged in an array with a stabilizer oligonucletoide attached. A set of ligation substrate oligonucleotides are placed in the solution and systematic assembly is carried out in the solid phase by sequential annealing, ligation and melting.
  • FIG. 15 depicts polynucleotide assembly using component oligonucleotides bound to a set of metal electrodes on a microelectronic chip. Each electrode can be controlled independently with respect to current and voltage.
  • FIG. 16 depicts generally a primer extension assembly method of the invention.
  • FIG. 17 provides a system diagram of the invention.
  • FIG. 18 depicts a perspective view of an instrument of the invention.
  • DETAILED DESCRIPTION
  • The complete sequence of complex genomes, including the human genome, make large scale functional approaches to genetics possible. The present invention outlines a novel approach to utilizing the results of genomic sequence information by computer-directed polynucleotide assembly based upon information available in databases such as the human genome database. Specifically, the present invention may be used to synthesize, assemble and select a novel, synthetic target polynucleotide sequence encoding a target polypeptide. The target polynucleotide may encode a target polypeptide that exhibits enhanced or altered biological activity as compared to a model polypeptide encoded by a natural (wild-type) or model polynucleotide sequence. Subsequently, standard assays may be used to survey the activity of an expressed target polypeptide. For example, the expressed target polypeptide can be assayed to determine its ability to carry out the function of the corresponding model polypeptide or to determine whether a target polypeptide exhibiting a new function has been produced. Thus, the present invention provides a means for the synthetically evolving a model polypeptide by synthesizing, in a computer-directed fashion, polynucleotides encoding a target polypeptide derived from a model polypeptide.
  • In one embodiment, the invention provides a method of synthesizing a target polynucleotide by providing a target polynucleotide sequence and identifying at least one initiating polynucleotide present in the target polynucleotide which includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang and a 3′ overhang. As used herein, a “target polynucleotide sequence” includes any nucleic acid sequence suitable for encoding a target polypeptide that can be synthesized by a method of the invention. A target polynucleotide sequence can be used to generate a target polynucleotide using an apparatus capable of assembling nucleic sequences. Generally, a target polynucleotide sequence is a linear segment of DNA having a double-stranded region; the segment may be of any length sufficiently long to be created by the hybridization of at least two oligonucleotides have complementary regions. It is contemplated that a target polynucleotide can be 100, 200, 300, 400, 800, 100, 1500, 200, 4000, 8000, 10000, 12000, 18,000, 20,000, 40,000, 80,000 or more base pairs in length. Indeed, it is contemplated that the methods of the present invention will be able to create entire artificial genomes of lengths comparable to known bacterial, yeast, viral, mammalian, amphibian, reptilian, or avian genomes. In more particular embodiments, the target polynucleotide is a gene encoding a polypeptide of interest. The target polynucleotide may further include non-coding elements such as origins of replication, telomeres, promoters, enhancers, transcription and translation start and stop signals, introns, exon splice sites, chromatin scaffold components and other regulatory sequences. The target polynucleotide may comprises multiple genes, chromosomal segments, chromosomes and even entire genomes. A polynucleotide of the invention may be derived from prokaryotic or eukaryotic sequences including bacterial, yeast, viral, mammalian, amphibian, reptilian, avian, plants, archebacteria and other DNA containing living organisms.
  • An “oligonucleotide”, as used herein, is defined as a molecule comprised of two or more deoxyribonucleotides or ribonucleotides, preferably more than three. Its exact size will depend on many factors, such as the reaction temperature, salt concentration, the presence of denaturants such as formamide, and the degree of complementarity with the sequence to which the oligonucleotide is intended to hybridize.
  • The term “nucleotide” as used herein can refer to nucleotides present in either DNA or RNA and thus includes nucleotides which incorporate adenine, cytosine, guanine, thymine and uracil as base, the sugar moiety being deoxyribose or ribose. It will be appreciated however that other modified bases capable of base pairing with one of the conventional bases, adenine, cytosine, guanine, thymine and uracil, may be used in an oligonucleotide employed in the present invention. Such modified bases include for example 8-azaguanine and hypoxanthine. If desired the nucleotides may carry a label or marker so that on incorporation into a primer extension product, they augment the signal associated with the primer extension product, for example for capture on to solid phase.
  • A “plus strand” oligonucleotide, by convention, includes a short, single-stranded DNA segment that starts with the 5′ end to the left as one reads the sequence. A “minus strand” oligonucleotide includes a short, single-stranded DNA segment that starts with the 3′ end to the left as one reads the sequence. Methods of synthesizing oligonucleotides are found in, for example, Oligonucleotide Synthesis: A Practical Approach, Gate, ed., IRL Press, Oxford (1984), incorporated herein by reference in its entirety. Solid-phase synthesis techniques have been provided for the synthesis of several peptide sequences on, for example, a number of “pins” (See e.g., Geysen et al., J. Immun. Meth. (1987) 102:259-274, incorporated herein by reference in its entirety).
  • Additional methods of forming large arrays of oligonucleotides and other polymer sequences in a short period of time have been devised. Of particular note, Pirrung et al., U.S. Pat. No. 5,143,854 (see also PCT Application No. WO 90/15070), Fodor et al., PCT Publication No. WO 92/10092 and Winkler et al., U.S. Pat. No. 6,136,269, all incorporated herein by reference, disclose methods of forming vast arrays of polymer sequences using, for example, light-directed synthesis techniques. See also, Fodor et al., Science (1991) 251:767-777, also incorporated herein by reference in its entirety. Some work has been done to automate synthesis of polymer arrays. For example, Southern, PCT Application No. WO 89/10977, describes the use of a conventional pen plotter to deposit three different monomers at twelve distinct locations on a substrate.
  • An “initiating polynucleotide sequence,” as used herein, is a sequence contained in a target polynucleotide sequence and identified by an algorithm of the invention. An “initiating polynucleotide” is the physical embodiment of an initiating polynucleotide sequence. For ligation assembly of a target polynucleotide, an initiating polynucleotide begins assembly by providing an anchor for hybridization of subsequent polynucleotides contiguous with the initiating polynucleotide. Thus, for ligation assembly, an initiating polynucleotide is partially double-stranded nucleic acid thereby providing single-stranded overhang(s) for annealing of a contiguous, double-stranded nucleic acid molecule. For primer extension assembly of a target polynucleotide, an initiating polynucleotide begins assembly by providing a template for hybridization of subsequent oligonucleotides contiguous with the initiating polynucleotide. Thus, for primer extension assembly, an initiating polynucleotide can be partially double-stranded or fully double-stranded.
  • In one embodiment, an initiating polynucleotide of the invention can be bound to a solid support for improved efficiency. The solid phase allows for the efficient separation of the assembled target polynucleotide from other components of the reaction. Different supports can be applied in the method. For example, supports can be magnetic latex beads or magnetic control pore glass beads that allows the desirable product from the reaction mixture to be magnetically separated. Binding the initiating polynucleotide to such beads can be accomplished by a variety of known methods, for example carbodiimide treatment (Gilham, Biochemistry 7:2809-2813 (1968); Mizutani and Tachbana, J. Chromatography 356:202-205 (1986); Wolf et al., Nucleic Acids Res. 15:2911-2926 (1987); Musso, Nucleic Acids Res. 15:5353-5372 (1987); Lund et al., Nucleic Acids Res. 16:10861-10880 (1988)).
  • The initiating polynucleotide attached to the solid phase can act as an anchor for the continued synthesis of the target polynucleotide. Assembly can be accomplished by addition of contiguous polynucleotides together with ligase for ligation assembly or by addition of oligonucleotides together with polymerase for primer extension assembly. After the appropriate incubation time, unbound components of the method can be washed out and the reaction can be repeated again to improve the efficiency of template utilization. Alternatively, another set of polynucleotides or oligonucleotides can be added to continue the assembly.
  • Solid phase, to be efficiently used for the synthesis, can contain pores with sufficient room for synthesis of the long nucleic acid molecules. The solid phase can be composed of material that cannot non-specifically bind any undesired components of the reaction. One way to solve the problem is to use control pore glass beads appropriate for long DNA molecules. The initiating polynucleotide can be attached to the beads through a long connector. The role of the connector is to position the initiating polynucleotide from the surface of the solid support at a desirable distance.
  • The method of the invention further includes identifying a second polynucleotide sequence present in the target polynucleotide which is contiguous with the initiating polynucleotide and includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a partially double-stranded polynucleotide comprised of a 5′ overhang, a 3′ overhang, or a 5′ overhang and a 3′ overhang, where at least one overhang of the second polynucleotide is complementary to at least one overhang of the initiating polynucleotide. Two or more oligonucleotides having complementary regions, where they are permitted, will “anneal” (i.e., base pair) under the appropriate conditions, thereby producing a double-stranded region. In order to anneal (i.e., hybridize), oligonucleotides must be at least partially complementary. The term “complementary to” is used herein in relation to nucleotides to mean a nucleotide that will base pair with another specific nucleotide. Thus adenosine triphosphate is complementary to uridine triphosphate or thymidine triphosphate and guanosine triphosphate is complementary to cytidine triphosphate.
  • As used herein, a 5′ or 3′ “overhang” means a region on the 5′ or 3′, or 5′ and 3′, end of a polynucleotide that is single-stranded, i.e. not base paired. An overhang provides a means for the subsequent annealing of a contiguous polynucleotide containing an overhang that is complementary to the overhang of the contiguous polynucleotide. Depending on the application envisioned, one will desire to employ varying conditions of annealing to achieve varying degrees of annealing selectivity.
  • For applications requiring high selectivity, one typically will desire to employ relatively stringent conditions to form the hybrids, e.g., one will select relatively low salt and/or high temperature conditions, such as provided by about 0.02 M to about 0.10 M NaCl at temperatures of about 50° C. to about 70° C. Such high stringency conditions tolerate little, if any, mismatch between the oligonucleotide and the template or target strand. It generally is appreciated that conditions can be rendered more stringent by the addition of increasing amounts of formamide.
  • For certain applications, for example, by analogy to substitution of nucleotides by site-directed mutagenesis, it is appreciated that lower stringency conditions may be used. Under these conditions, hybridization may occur even though the sequences of probe and target strand are not perfectly complementary, but are mismatched at one or more positions. Conditions may be rendered less stringent by increasing salt concentration and decreasing temperature. For example, a medium stringency condition could be provided by about 0.1 to 0.25 M NaCl at temperatures of about 37° C. to about 55° C., while a low stringency condition could be provided by about 0.15 M to about 0.9 M salt, at temperatures ranging from about 20° C. to about 55° C. Thus, hybridization conditions can be readily manipulated depending on the desired results.
  • In certain embodiments, it will be advantageous to determine the hybridization of oligonucleotides by employing a label. A wide variety of appropriate labels are known in the art, including fluorescent, radioactive, enzymatic or other ligands; such as avidin/biotin, which are capable of being detected. In preferred embodiments, one may desire to employ a fluorescent label or an enzyme tag such as urease, alkaline phosphatase or peroxidase, instead of radioactive or other environmentally undesirable reagents. In the case of enzyme tags, colorimetric indicator substrates are known that can be employed to provide a means for detection visible to the human eye or spectrophotometrically to identify whether specific hybridization with complementary oligonucleotide has occurred.
  • In embodiments involving a solid phase, for example, at least one oligonucleotide of an initiating polynucleotide is adsorbed or otherwise affixed to a selected matrix or surface. This fixed, single-stranded nucleic acid is then subjected to hybridization with the complementary oligonucleotides under desired conditions. The selected conditions will also depend on the particular circumstances based on the particular criteria required (depending, for example, on the G+C content, type of target nucleic acid, source of nucleic acid, size of hybridization probe, etc.). Following washing of the hybridized surface to remove non-specifically bound oligonucleotides, the hybridization may be detected, or even quantified, by means of the label.
  • The method of the invention further provides a third polynucleotide present in the target polynucleotide which is contiguous with the initiating sequence and provides a 5′ overhang, a 3′ overhang, or a 5′ overhang and a 3′ overhang, where at least one overhang of the third polynucleotide is complementary to at least one overhang of the initiating polynucleotide which is not complementary to an overhang of the second polynucleotide.
  • The method further provides contacting the initiating polynucleotide with the second polynucleotide and the third polynucleotide under conditions and for such time suitable for annealing, the contacting resulting in a contiguous double-stranded polynucleotide, resulting in the bi-directional extension of the initiating polynucleotide. The annealed polynucleotides are optionally contacted with a ligase under conditions suitable for ligation. The method discussed above is optionally repeated to sequentially add double-stranded polynucleotides to the extended initiating polynucleotide through repeated cycles of annealing and ligation.
  • A target polynucleotide sequence can be designed de novo or derived from a “model polynucleotide sequence”. As used herein, a “model polynucleotide sequence” includes any nucleic acid sequence that encodes a model polypeptide sequence. A model polypeptide sequence provides a basis for designing a modified polynucleotide such that a target polynucleotide incorporating the desired modification is synthesized.
  • The present invention provides also provides methods that can be used to synthesize, de novo, polynucleotides that encode sets of genes, either naturally occurring genes expressed from natural or artificial promoter constructs or artificial genes derived from synthetic DNA sequences, which encode elements of biological systems that perform a specified function or attribution of an artificial organism as well as entire genomes. In producing such systems and genomes, the present invention provides the synthesis of a replication-competent, double-stranded polynucleotide, wherein the polynucleotide has an origin of replication, a first coding region and a first regulatory element directing the expression of the first coding region. By replication competent, it is meant that the polynucleotide is capable of directing its own replication. Thus, it is envisioned that the polynucleotide will possess all the cis-acting signals required to facilitate its own synthesis. In this respect, the polynucleotide will be similar to a plasmid or a virus, such that once placed within a cell, it is capable of replication by a combination of the polynucleotide's and cellular functions.
  • A polynucleotide sequence defining a gene, genome, set of genes or protein sequence can be designed in a computer-assisted manner (discussed below) and used to generate a set of parsed oligonucleotides covering the plus (+) and minus (−) strand of the sequence. As used herein, a “parsed” means a target polynucleotide sequence has been delineated in a computer-assisted manner such that a series of contiguous oligonucleotide sequences are identified. The oligonucleotide sequences are individually synthesized and used in a method of the invention to generate a target polynucleotide. The length of an oligonucleotide is quite variable. Preferably, oligonucleotides used in the methods of the invention are between about 15 and 100 bases and more preferably between about 20 and 50 bases. Specific lengths include, but are not limited to 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64. 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 and 100 bases. Depending on the size, the overlap between the oligonucleotides having partial complementarity may be designed to be between 5 and 75 bases per oligonucleotide pair.
  • The oligonucleotides preferably are treated with polynucleotide kinase, for example, T4 polynucleotide kinase. The kinasing can be performed prior to, or after, mixing of the oligonucleotides set or after, but before annealing. After annealing, the oligonucleotides are treated with an enzyme having a ligating function. For example, a DNA ligase typically will be employed for this function. However, topoisomerase, which does not require 5′ phosphorylation, is rapid and operates at room temperature, and may be used instead of ligase. For example, 50 base pair oligonucleotides overlapping by 25 bases can be synthesized by an oligonucleotide array synthesizer (OAS). A 5′ (+) strand set of oligonucleotides is synthesized in one 96-well plate and the second 3′ or (−) strand set is synthesized in a second 96-well microtiter plate. Synthesis can be carried out using phosphoramidite chemistry modified to miniaturize the reaction size and generate small reaction volumes and yields in the range of 2 to 5 nmole. Synthesis is done on controlled pore glass beads (CPGs), then the completed oligonucleotides are deblocked, deprotected and removed from the beads. The oligonucleotides are lyophilized, re-suspended in water and 5′ phosphorylated using polynucleotide kinase and ATP to enable ligation.
  • The set of arrayed oligonucleotide sequences in the plate can be assembled using a mixed pooling strategy. For example, systematic pooling of component oligonucleotides can be performed using a modified Beckman Biomek automated pipetting robot, or another automated lab workstation. The fragments can be combined with buffer and enzyme (Taq I DNA ligase or Egea Assemblase™, for example). Pooling can be performed in microwell plates. After each step of pooling, the temperature is ramped to enable annealing and ligation, then additional pooling carried out.
  • Target polynucleotide assembly involves forming a set of intermediates. A set of intermediates can include a plus strand oligonucleotide annealed to a minus strand oligonucleotide, as described above. The annealed intermediate can be formed by providing a single plus strand oligonucleotide annealed to a single minus strand oligonucleotide.
  • Alternatively, two or more oligonucleotides may comprise the plus strand or the minus strand. For example, in order to construct a polynucleotide (e.g., an initiating polynucleotide) which can be used to assemble a target polynucleotide of the invention, three or more oligonucleotides can be annealed. Thus, a first plus strand oligonucleotide, a second plus strand oligonucleotide contiguous with the first plus strand oligonucleotide, and a minus strand oligonucleotide having a first contiguous sequence which is at least partially complementary to the first plus strand oligonucleotide and second contiguous sequence which is at least partially complementary to the second plus strand oligonucleotide can be annealed to form a partially double-stranded polynucleotide. The polynucleotide can include a 5′ overhang, a 3′ overhang, or a 5′ overhang and a 3′ overhang. The first plus strand oligonucleotide and second plus strand oligonucleotide are contiguous sequences such that they are ligatable. The minus strand oligonucleotide is partially complementary to both plus strand oligonucleotides and acts as a “bridge” or “stabilizer” sequence by annealing to both oligonucleotides. Subsequent polynucleotides comprised of more than two oligonucleotides annealed as previously described, can be used to assemble a target polynucleotide in a manner resulting in a contiguous double-stranded polynucleotide.
  • An example of using two or more plus strand oligonucleotides to assemble a polynucleotide is shown in FIG. 3. A triplex of three oligonucleotides of about 50 bp each, which overlap by about 25 bp form a “nicked” intermediate. Two of these oligonucleotides provide a ligation substrate joined by ligase and the third oligonucleotide is a stabilizer that brings together two specific sequences by annealing resulting in the formation of a part of the final polynucleotide construct. This intermediate provides a substrate for DNA ligase which, through its nick sealing activity, joins the two 50-base pair oligonucleotides into a single 100 base single-stranded polynucleotide.
  • Following initial pooling and formation of annealed products, the products are assembled into increasingly larger polynucleotides. For example, following triplex formation of oligonucleotides, sets of triplexes are systematically joined, ligated, and assembled. Each step can be mediated by robotic pooling, ligation and thermal cycling to achieve annealing and denaturation. The final step joins assembled pieces into a complete sequence representing all of the fragments in the array. Since the efficiency of yield at each step is less than 100%, the mass amount of completed product in the final mixture may be very small. Optionally, additional specific oligonucleotide primers, usually 15 to 20 bases and complementary to the extreme ends of the assembly, can be annealed and PCR amplification carried out, thereby amplifying and purifying the final full-length product.
  • The methods of the invention provide several improvements over existing polynucleotide synthesis technology. For example, synthesis can utilize microdispensing piezioelectric or microsolenoid nanodispensors allowing very fast synthesis, much smaller reaction volumes and higher density plates as synthesis vessels. The instrument will use up to 1536 well plates giving a very high capacity. Additionally, controlled pooling can be performed by a microfluidic manifold that will move individual oligonucleotides though microchannels and mix/ligate in a controlled way. This will obviate the need for robotic pipetting and increases speed and efficiency. Thus, an apparatus that accomplishes a method of the invention will have a greater capability for simultaneous reactions giving an overall larger capacity for gene length.
  • Once target polynucleotide have been synthesized using a method of the present invention, it may be necessary to screen the sequences for analysis of function. Specifically contemplated by the present inventor are chip-based DNA technologies. Briefly, these techniques involve quantitative methods for analyzing large numbers of genes rapidly and accurately. By tagging genes with oligonucleotides or using fixed probe arrays, one can employ chip technology to segregate target molecules as high-density arrays and screen these molecules on the basis of hybridization.
  • The use of combinatorial synthesis and high throughput screening assays are well known to those of skill in the art. For example, U.S. Pat. Nos. 5,807,754; 5,807,683; 5,804,563; 5,789,162; 5,783,384; 5,770,358; 5,759,779; 5,747,334;5,686,242; 5,198,346; 5,738,996; 5,733, 743; 5,714,320; and 5,663,046 (each specifically incorporated herein by reference) describe screening systems useful for determining the activity of a target polypeptide. These patents teach various aspects of the methods and compositions involved in the assembly and activity analyses of high-density arrays of different polysubunits (polynucleotides or polypeptides). As such it is contemplated that the methods and compositions described in the patents listed above may be useful in assaying the activity profiles of the target polypeptides of the present invention.
  • In another embodiment, the invention provides a method of synthesizing a target polynucleotide by providing a target polynucleotide sequence and identifying at least one initiating polynucleotide sequence present in the target polynucleotide sequence that includes at least one plus strand oligonucleotide annealed to at least one minus strand oligonucleotide resulting in a double-stranded polynucleotide. The initiating polynucleotide is contacted under conditions suitable for primer annealing with a first oligonucleotide having partial complementarity to the 3′ portion of the plus strand of the initiating polynucleotide, and a second oligonucleotide having partial complementarity to the 3′ portion of the minus strand of the initiating polynucleotide. Primer extension subsequently performed using polynucleotide synthesis from the 3′-hydroxyl of: 1) the plus strand of the initiating polynucleotide; 2) the annealed first oligonucleotide; 3) the minus strand of the initiating polynucleotide; and 4) the annealed second oligonucleotide. The synthesis results in the initiating sequence being extended bi-directionally thereby forming a nascent extended initiating polynucleotide. The extended initiating sequence can be further extended by repeated cycles of annealing and primer extension.
  • As previously noted, oligonucleotides can be used as building blocks to assemble polynucleotides through annealing and ligation reactions. Alternatively, oligonucleotides can be used as primers to manufacture polynucleotides through annealing and primer extension reactions. The term “primer” is used herein to refer to a binding element which comprises an oligonucleotide, whether occurring naturally as in a purified restriction digest or produced synthetically, which is capable of acting as a point of initiation of synthesis when placed under conditions in which synthesis of a primer extension product which is complementary to a nucleic acid strand is induced, i.e., in the presence of appropriate nucleotides and an agent for polymerization such as a DNA polymerase in an appropriate buffer (“buffer” includes pH, ionic strength, cofactors, etc.) and at a suitable temperature.
  • The primer is preferably single stranded for maximum efficiency in amplification, but may alternatively be double stranded. If double stranded, the primer is first treated to separate its strands before being used to prepare extension products. Preferably, the primer is an oligodeoxyribonucleotide. The primer must be sufficiently long to prime the synthesis of extension products in the presence of the agent for polymerization. The exact lengths of the primers will depend on many factors, including temperature and source of primer and use of the method. Primers having only short sequences capable of hybridization to the target nucleotide sequence generally require lower temperatures to form sufficiently stable hybrid complexes with the template.
  • The primers herein are selected to be “substantially” complementary to the different strands of each specific sequence to be amplified. This means that the primers must be sufficiently complementary to hybridize with their respective strands. Therefore, the primer sequence need not reflect the exact sequence of the template. Commonly, however, the primers have exact complementarity except with respect to analyses effected according to the method described in Nucleic Acids Research 17 (7) 2503-2516 (1989) or a corresponding method employing linear amplification or an amplification technique other than the polymerase chain reaction.
  • The agent for primer extension of an oligonucleotide may be any compound or system that will function to accomplish the synthesis of primer extension products, including enzymes. Suitable enzymes for this purpose include, for example, E. coli DNA Polymerase I, Klenow fragment of E. coli DNA polymerase I, T4 DNA polymerase, other available DNA polymerases, reverse transcriptase, and other enzymes, including thermostable enzymes. The term “thermostable enzyme” as used herein refers to any enzyme that is stable to heat and is heat resistant and catalyses (facilitates) combination of the nucleotides in the proper manner to form the primer extension products which are complementary to each nucleic acid strand. Generally, the synthesis will be initiated at the 3′ end of each primer and will proceed in the 5′ direction along the template strand, until synthesis terminates. A preferred thermostable enzyme that may be employed in the process of the present invention is that which can be extracted and purified from Thermus aquaticus. Such an enzyme has a molecular weight of about 86,000-90,000 daltons. Thermus aquaticus strain YT1 is available without restriction from the American Type Culture Collection, 12301 Parklawn Drive, Rockville, Md., U.S.A. as ATCC 25,104.
  • Processes for amplifying a desired target polynucleotide are known and have been described in the literature. K. Kleppe et al in J. Mol. Biol., (1971), 56, 341-361 disclose a method for the amplification of a desired DNA sequence. The method involves denaturation of a DNA duplex to form single strands. The denaturation step is carried out in the presence of a sufficiently large excess of two nucleic acid primers that hybridize to regions adjacent to the desired DNA sequence. Upon cooling two structures are obtained each containing the full length of the template strand appropriately complexed with primer. DNA polymerase and a sufficient amount of each required nucleoside triphosphate are added whereby two molecules of the original duplex are obtained. The above cycle of denaturation, primer addition and extension are repeated until the appropriate number of copies of the desired target polynucleotide is obtained.
  • The present invention further provides a method for the expression and isolation of a target polypeptide encoded by a target polynucleotide. The method includes incorporating a target polynucleotide synthesized by a method of the invention into an expression vector; introducing the expression vector of into a suitable host cell; culturing the host cell under conditions and for such time as to promote the expression of the target polypeptide encoded by the target polynucleotide; and isolating the target polypeptide.
  • The invention can be used to modify certain functional, structural, or phylogenic features of a model polynucleotide encoding a model polypeptide resulting in an altered target polypeptide. An input or model polynucleotide sequence encoding a model polypeptide can be electronically manipulated to determine a potential for an effect of an amino acid change (or variance) at a particular site or multiple sites in the model polypeptide. Once identified, a novel target polynucleotide sequence is assembled by a method of the invention such that the target polynucleotide encodes a target polypeptide possessing a characteristic different from that of the model polypeptide.
  • The methods of the invention may rely on the use of public sequence and structure databases. These databases become more robust as more and more sequences and structures are added. Information regarding the amino acid sequence of a target polypeptide and the tertiary structure of the polypeptide can be used to synthesize oligonucleotides that can be assembled into a target polynucleotide encoding a target polypeptide. A model polypeptide should have sufficient structural information to analyze the amino acids involved in the function of the polypeptide. The structural information can be derived from x-ray crystallography, NMR, or some other technique for determining the structure of a protein at the amino acid or atomic level. Once selected, the sequence and structural information obtained from the model polypeptide can be used to generate a plurality of polynucleotides encoding a plurality of variant amino acid sequences that comprise a target polypeptide. Thus, a model polypeptide can be selected based on overall sequence similarity to the target protein or based on the presence of a portion having sequence similarity to a portion of the target polypeptide.
  • A “polypeptide”, as used herein, is a polymer in which the monomers are alpha amino acids and are joined together through amide bonds. Amino acids may be the L-optical isomer or the D-optical isomer. Polypeptides are two or more amino acid monomers long and are often more than 20 amino acid monomers long. Standard abbreviations for amino acids are used (e.g., P for proline). These abbreviations are included in Stryer, Biochemistry, Third Ed., 1988, which is incorporated herein by reference for all purposes. With respect to polypeptides, “isolated” refers to a polypeptide that constitutes the major component in a mixture of components, e.g., 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more by weight. Isolated polypeptides typically are obtained by purification from an organism in which the polypeptide has been produced, although chemical synthesis is also possible. Method of polypeptide purification includes, for example, chromatography or immunoaffinity techniques.
  • Polypeptides of the invention may be detected by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis followed by Coomassie Blue-staining or Western blot analysis using monoclonal or polyclonal antibodies that have binding affinity for the polypeptide to be detected.
  • A “chimeric polypeptide,” as used herein, is a polypeptide containing portions of amino acid sequence derived from two or more different proteins, or two or more regions of the same protein that are not normally contiguous.
  • A “ligand”, as used herein, is a molecule that is recognized by a receptor. Examples of ligands that can be investigated by this invention include, but are not restricted to, agonists and antagonists for cell membrane receptors, toxins and venoms, viral epitopes, hormones, opiates, steroids, peptides, enzyme substrates, cofactors, drugs, lectins, sugars, oligonucleotides, nucleic acids, oligosaccharides, and proteins.
  • A “receptor”, as used herein, is a molecule that has an affinity for a ligand. Receptors may be naturally occurring or manmade molecules. They can be employed in their unaltered state or as aggregates with other species. Receptors may be attached, covalently or noncovalently, to a binding member, either directly or via a specific binding substance. Examples of receptors which can be employed by this invention include, but are not restricted to, antibodies, cell membrane receptors, monoclonal antibodies and antisera reactive with specific antigenic determinants, viruses, cells, drugs, polynucleotides, nucleic acids, peptides, cofactors, lectins, sugars, polysaccharides, cellular membranes, and organelles. A “ligand receptor pair” is formed when two molecules have combined through molecular recognition to form a complex.
  • Specific examples of polypeptides which can synthesized by this invention include but are not restricted to:
  • a) Microorganism receptors: Determination of ligands that bind to microorganism receptors such as specific transport proteins or enzymes essential to survival of microorganisms would be a useful tool for discovering new classes of antibiotics. Of particular value would be antibiotics against opportunistic fungi, protozoa, and bacteria resistant to antibiotics in current use.
  • b) Enzymes: For instance, a receptor can comprise a binding site of an enzyme such as an enzyme responsible for cleaving a neurotransmitter; determination of ligands for this type of receptor to modulate the action of an enzyme that cleaves a neurotransmitter is useful in developing drugs that can be used in the treatment of disorders of neurotransmission.
  • c) Antibodies: For instance, the invention may be useful in investigating a receptor that comprises a ligand-binding site on an antibody molecule which combines with an epitope of an antigen of interest; determining a sequence that mimics an antigenic epitope may lead to the development of vaccines in which the immunogen is based on one or more of such sequences or lead to the development of related diagnostic agents or compounds useful in therapeutic treatments such as for autoimmune diseases (e.g., by blocking the binding of the “self” antibodies).
  • d) Polynucleotides: Sequences of polynucleotides may be synthesized to establish DNA or RNA binding sequences that act as receptors for synthesized sequence.
  • e) Catalytic Polypeptides: Polymers, preferably antibodies, which are capable of promoting a chemical reaction involving the conversion of one or more reactants to one or more products. Such polypeptides generally include a binding site specific for at least one reactant or reaction intermediate and an active functionality proximate to the binding site, which functionality is capable of chemically modifying the bound reactant. Catalytic polypeptides and others are described in, for example, PCT Publication-No. WO 90/05746, WO 90/05749, and WO 90/05785, which are incorporated herein by reference for all purposes.
  • f) Hormone receptors: Identification of the ligands that bind with high affinity to a receptor such as the receptors for insulin and growth hormone is useful in the development of, for example, an oral replacement of the daily injections which diabetics must take to relieve the symptoms of diabetes or a replacement for growth hormone. Other examples of hormone receptors include the vasoconstrictive hormone receptors; determination of ligands for these receptors may lead to the development of drugs to control blood pressure.
  • g) Opiate receptors: Determination of ligands which bind to the opiate receptors in the brain is useful in the development of less-addictive replacements for morphine and related drugs.
  • In the context of a polypeptide, the term “structure” refers to the three dimensional arrangement of atoms in the protein. “Function” refers to any measurable property of a protein. Examples of protein function include, but are not limited to, catalysis, binding to other proteins, binding to non-protein molecules (e.g., drugs), and isomerization between two or more structural forms. “Biologically relevant protein” refers to any protein playing a role in the life of an organism.
  • To identify significant structural motifs, the sequence of the model polypeptide is examined for matches to the entries in one or more databases of recognized domains, e.g., the PROSITE database domains (Bairoch, Nucl. Acids. Res. 24:217, 1997) or the pfam HMM database (Bateman et al., (2000) Nucl. Acids. Res. 28:263). The PROSITE database is a compilation of two types of sequence signatures-profiles, typically representing whole protein domains, and patterns typically representing just the most highly conserved functional or structural aspects of protein domains.
  • The methods of the invention can be used to generate polypeptides containing polymorphisms that have an effect on a catalytic activity of a target polypeptide or a non-catalytic activity of the target polypeptide (e.g., structure, stability, binding to a second protein or polypeptide chain, binding to a nucleic acid molecule, binding to a small molecule, and binding to a macromolecule that is neither a protein nor a nucleic acid). For example, the invention provides a means for assembling any polynucleotide sequence encoding a target polypeptide such that the encoded polypeptide can be expressed and screened for a particular activity. By altering particular amino acids at specific points in the target polypeptide, the operating temperature, operating pH, or any other characteristic of a polypeptide can be manipulated resulting in a polypeptide with a unique activity. Thus, the methods of the invention can be used to identify amino acid substitutions that can be made to engineer the structure or function of a polypeptide of interest (e.g., to increase or decrease a selected activity or to add or remove a selective activity).
  • In addition, the methods of the invention can be used in the identification and analysis of candidate polymorphisms for polymorphism-specific targeting by pharmaceutical or diagnostic agents, for the identification and analysis of candidate polymorphisms for pharmacogenomic applications, and for experimental biochemical and structural analysis of pharmaceutical targets that exhibit amino acid polymorphism.
  • A library of target polynucleotides encoding a plurality of target polypeptides can be prepared by the present invention. Host cells are transformed by artificial introduction of the vectors containing the target polynucleotide by inoculation under conditions conducive for such transformation. The resultant libraries of transformed clones are then screened for clones which display activity for the polypeptide of interest in a phenotypic assay for activity.
  • A target polynucleotide of the invention can be incorporated (i.e., cloned) into an appropriate vector. For purposes of expression, the target sequences encoding a target polypeptide of the invention may be inserted into a recombinant expression vector. The term “recombinant expression vector” refers to a plasmid, virus, or other vehicle known in the art that has been manipulated by insertion or incorporation of the polynucleotide sequence encoding a target polypeptide of the invention. The expression vector typically contains an origin of replication, a promoter, as well as specific genes that allow phenotypic selection of the transformed cells. Vectors suitable for use in the present invention include, but are not limited to, the T7-based expression vector for expression in bacteria (Rosenberg et al., Gene, 56:125, 1987), the pMSXND-expression vector for expression in mammalian cells (Lee and Nathans, J. Biol. Chem., 263:3521, 1988), baculovirus-derived vectors for expression in insect cells, cauliflower mosaic virus, CaMV, tobacco mosaic virus, TMV.
  • Depending on the vector utilized, any of a number of suitable transcription and translation elements, including constitutive and inducible promoters, transcription enhancer elements, transcription terminators, etc. may be used in the expression vector (see, e.g., Bitter et al., Methods in Enzymology, 153:516-544, 1987). These elements are well known to one of skill in the art.
  • The term “operably linked” or “operably associated” refers to functional linkage between the regulatory sequence and the polynucleotide sequence regulated by the regulatory sequence. The operably linked regulatory sequence controls the expression of the product expressed by the polynucleotide sequence. Alternatively, the functional linkage also includes an enhancer element.
  • “Promoter” means a nucleic acid regulatory sequence sufficient to direct transcription. Also included in the invention are those promoter elements that are sufficient to render promoter-dependent polynucleotide sequence expression controllable for cell-type specific, tissue specific, or inducible by external signals or agents; such elements may be located in the 5′ or 3′ regions of the native gene, or in the introns.
  • “Gene expression” or “polynucleotide sequence expression” means the process by which a nucleotide sequence undergoes successful transcription and translation such that detectable levels of the delivered nucleotide sequence are expressed in an amount and over a time period so that a functional biological effect is achieved.
  • In yeast, a number of vectors containing constitutive or inducible promoters may be used. (Current Protocols in Molecular Biology, Vol. 2, Ed. Ausubel et al., Greene Publish. Assoc. & Wiley Interscience, Ch. 13, 1988; Grant et al., “Expression and Secretion Vectors for Yeast,” in Methods in Enzymology, Eds. Wu & Grossman, Acad. Press, N.Y., Vol. 153, pp. 516-544, 1987; Glover, DNA Cloning, Vol. II, IRL Press, Wash., D.C., Ch. 3, 1986; “Bitter, Heterologous Gene Expression in Yeast,” Methods in Enzymology, Eds. Berger & Kimmel, Acad. Press, N.Y., Vol. 152, pp. 673-684, 1987; and The Molecular Biology of the Yeast Saccharomyces, Eds. Strathern et al., Cold Spring Harbor Press, Vols. I and II, 1982). A constitutive yeast promoter, such as ADH or LEU2, or an inducible promoter, such as GAL, may be used (“Cloning in Yeast,” Ch. 3, R. Rothstein In: DNA Cloning Vol. 11, A Practical Approach, Ed. DM Glover, IRL Press, Wash., D.C., 1986). Alternatively, vectors may be used which promote integration of foreign DNA sequences into the yeast chromosome.
  • In certain embodiments, it may be desirable to include specialized regions known as telomeres at the end of a target polynucleotide sequence. Telomeres are repeated sequences found at chromosome ends and it has long been known that chromosomes with truncated ends are unstable, tend to fuse with other chromosomes and are otherwise lost during cell division.
  • Some data suggest that telomeres interact with the nucleoprotein complex and the nuclear matrix. One putative role for telomeres includes stabilizing chromosomes and shielding the ends from degradative enzyme.
  • Another possible role for telomeres is in replication. According to present doctrine, replication of DNA requires starts from short RNA primers annealed to the T-end of the template. The result of this mechanism is an “end replication problem” in which the region corresponding to the RNA primer is not replicated. Over many cell divisions, this will result in the progressive truncation of the chromosome. It is thought that telomeres may provide a buffer against this effect, at least until they are themselves eliminated by this effect. A further structure that may be included in target polynucleotide is a centromere.
  • In certain embodiments of the invention, the delivery of a nucleic acid in a cell may be identified in vitro or in vivo by including a marker in the expression construct. The marker would result in an identifiable change to the transfected cell permitting easy identification of expression.
  • An expression vector of the invention can be used to transform a target cell. By “transformation” is meant a genetic change induced in a cell following incorporation of new DNA (i.e., DNA exogenous to the cell). Where the cell is a mammalian cell, the genetic change is generally achieved by introduction of the DNA into the genome of the cell. By “transformed cell” is meant a cell into which (or into an ancestor of which) has been introduced, by means of recombinant DNA techniques. Transformation of a host cell with recombinant DNA may be carried out by conventional techniques as are well known to those skilled in the art. Where the host is prokaryotic, such as E. coli, competent cells that are capable of DNA uptake can be prepared from cells harvested after exponential growth phase and subsequently treated by the CaCl2 method by procedures well known in the art. Alternatively, MgCl2 or RbCl can be used. Transformation can also be performed after forming a protoplast of the host cell or by electroporation.
  • A target polypeptide of the invention can be produced in prokaryotes by expression of nucleic acid encoding the polypeptide. These include, but are not limited to, microorganisms, such as bacteria transformed with recombinant bacteriophage DNA, plasmid DNA, or cosmid DNA expression vectors encoding a polypeptide of the invention. The constructs can be expressed in E. coli in large scale for in vitro assays. Purification from bacteria is simplified when the sequences include tags for one-step purification by nickel-chelate chromatography. The construct can also contain a tag to simplify isolation of the polypeptide. For example, a polyhistidine tag of, e.g., six histidine residues, can be incorporated at the amino terminal end, or carboxy terminal end, of the protein. The polyhistidine tag allows convenient isolation of the protein in a single step by nickel-chelate chromatography. The target polypeptide of the invention can also be engineered to contain a cleavage site to aid in protein recovery. Alternatively, the polypeptides of the invention can be expressed directly in a desired host cell for assays in situ.
  • When the host is a eukaryote, such methods of transfection of DNA as calcium phosphate co-precipitates, conventional mechanical procedures, such as microinjection, electroporation or biollistic techniques, insertion of a plasmid encased in liposomes, or virus vectors may be used. Eukaryotic cells can also be cotransfected with DNA sequences encoding a polypeptide of the invention, and a second foreign DNA molecule encoding a selectable phenotype, such as the herpes simplex thymidine kinase gene. Another method is to use a eukaryotic viral vector, such as simian virus 40 (SV40) or bovine papilloma virus, to transiently infect or transform eukaryotic cells and express the protein. (Eukaryotic Viral Vectors, Cold Spring Harbor Laboratory, Gluzman ed., 1982). Preferably, a eukaryotic host is utilized as the host cell, as described herein.
  • Eukaryotic systems, and preferably mammalian expression systems, allow for proper post-translational modifications of expressed mammalian proteins to occur. Eukaryotic cells that possess the cellular machinery for proper processing of the primary transcript, glycosylation, phosphorylation, and advantageously secretion of the gene product should be used as host cells for the expression of the polypeptide of the invention. Such host cell lines may include, but are not limited to, CHO, VERO, BHK, HeLa, COS, MDCK, Jurkat, HEK-293, and WI38.
  • For long-term, high-yield production of recombinant proteins, stable expression is preferred. Rather than using expression vectors that contain viral origins of replication, host cells can be transformed with the cDNA encoding a target polypeptide of the invention controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker. The selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into their chromosomes and grow to form foci that, in turn, can be cloned and expanded into cell lines. For example, following the introduction of foreign DNA, engineered cells may be allowed to grow for 1-2 days in an enriched media, and then are switched to a selective media. A number of selection systems may be used, including, but not limited to, the herpes simplex virus thymidine kinase (Wigler et al., Cell, 11:223, 1977), hypoxanthine-guanine phosphoribosyltransferase (Szybalska & Szybalski, Proc. Natl. Acad. Sci. USA, 48:2026, 1962), and adenine phosphoribosyltransferase (Lowy et al., Cell, 22:817, 1980) genes can be employed in tk-, hgprt- or aprt-cells, respectively. Also, antimetabolite resistance can be used as the basis of selection for dhfr, which confers resistance to methotrexate (Wigler et al., Proc. Natl. Acad. Sci. USA, 77:3567, 1980; O'Hare et al., Proc. Natl. Acad. Sci. USA, 8:1527, 1981); gpt, which confers resistance to mycophenolic acid (Mulligan & Berg, Proc. Natl. Acad. Sci. USA, 78:2072, —1981; neo, which confers resistance to the aminoglycoside G-4.18 (Colberre-Garapin et al., J. Mol. Biol., 150:1, 1981); and hygro, which confers resistance to hygromycin genes (Santerre et al., Gene, 30:147, 1984). Recently, additional selectable genes have been described, namely trpB, which allows cells to utilize indole in place of tryptophan; hisD, which allows cells to utilize histinol in place of histidine (Hartman & Mulligan, Proc. Natl. Acad. Sci. USA, 85:8047, 1988); and ODC (ornithine decarboxylase), which confers resistance to the ornithine decarboxylase inhibitor, 2-(difluoromethyl)-DL-ornithine, DFMO (McConlogue L., In: Current Communications in Molecular Biology, Cold Spring Harbor Laboratory, ed., 1987).
  • Techniques for the isolation and purification of either microbially or eukaryotically expressed polypeptides of the invention may be by any conventional means, such as, for example, preparative chromatographic separations and immunological separations, such as those involving the use of monoclonal or polyclonal antibodies or antigen.
  • A target polynucleotide, or expression construct containing a target polynucleotide, may be entrapped in a liposome. Liposomes are vesicular structures characterized by a phospholipid bilayer membrane and an inner aqueous medium. Multilarnellar liposomes have multiple lipid layers separated by aqueous medium and form spontaneously when phospholipids are suspended in an excess of aqueous solution. The lipid components undergo self-rearrangement before the formation of closed structures and entrap water and dissolved solutes between the lipid bilayers. The liposome may be complexed with a hernagglutinating virus (HVJ). This has been shown to facilitate fusion with the cell membrane and promote cell entry of liposome-encapsulated DNA. In other embodiments, the liposome may be complexed or employed in conjunction with nuclear non-histone chromosomal proteins (HMG-1). In yet further embodiments, the liposome may be complexed or employed in conjunction with both HVJ and HMG-1. In that such expression constructs have been successfully employed in transfer and expression of nucleic acid in vitro and in vivo, then they are applicable for the present invention. Where a bacterial promoter is employed in the DNA construct, it also will be desirable to include within the liposome an appropriate bacterial polymerase.
  • The present invention describes methods for enabling the creation of a target polynucleotide based upon information only, i.e., without the requirement for existing genes, DNA molecules or genomes. Generally, using computer software, it is possible to construct a virtual polynucleotide in the computer. This polynucleotide consists of a string of DNA bases, G, A, T or C, comprising for example an entire artificial polynucleotide sequence in a linear string. Following construction of a sequence, computer software is then used to parse the target sequence breaking it down into a set of overlapping oligonucleotides of specified length. This results in a set of shorter DNA sequences that overlap to cover the entire length of the target polynucleotide in overlapping sets.
  • Typically, a gene of 1000 bases pairs would be broken down into 20 100-mers where 10 of these comprise one strand and 10 of these comprise the other strand. They would be selected to overlap on each strand by 25 to 50 base pairs.
  • The degeneracy of the genetic code permits substantial freedom in the choice of codons for any particular amino acid sequence. Transgenic organisms such as plants frequently prefer particular codons that, though they encode the same protein, may differ from the codons in the organism from which the gene was derived. For example, U.S. Pat. No. 5,380,831 to Adang et al. describes the creation of insect resistant transgenic plants that express the Bacillus thuringiensis (Bt) toxin gene. The Bt crystal protein, an insect toxin, is encoded by a full-length gene that is poorly expressed in transgenic plants. In order to improve expression in plants, a synthetic gene encoding the protein containing codons preferred in plants was substituted for the natural sequence. The invention disclosed therein comprised a chemically synthesized gene encoding an insecticidal protein which is frequently equivalent to a native insecticidal protein of Bt. The synthetic gene was designed to be expressed in plants at a level higher than a native Bt gene.
  • In designing a target polynucleotide that encodes a particular polypeptide, the hydropathic index of amino acids may be considered. The importance of the hydropathic amino acid index in conferring interactive biologic function on a protein is generally understood in the art. Each amino acid has been assigned a hydropathic index on the basis of their hydrophobicity and charge characteristics, these are: Isoleucine (+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (−0.4); threonine (47); serine (−0.8); tryptophan (−0.9); tyrosine (−1.3); proline (−1.6); histidine (−3.2); glutamate (−3.5); glutamine (−3.5); aspartate (−3.5); asparagine (−3.5); lysine (−3.9); and arginine (45).
  • It is known in the art that certain amino acids may be substituted by other amino acids having a similar hydropathic index or score and still result in a protein with similar biological activity, i.e., still obtain a biological functionally equivalent protein. In making such changes, the substitution of amino acids whose hydropathic indices are within ±2 is preferred, those which are within ±I are particularly preferred, and those within ±0.5 are even more particularly preferred.
  • It is also understood in the art that the substitution of like amino acids can be made effectively on the basis of hydrophilicity. U.S. Pat. No. 4,554,101, incorporated herein by reference, states that the greatest local average hydrophilicity of a protein, as governed by the hydrophilicity of its adjacent amino acids, correlates with a biological property of the protein.
  • As detailed in U.S. Pat. No. 4,554,101, the following hydrophilicity values have been assigned to amino acid residues: arginine (+3.0); lysine (+3.0); aspartate (+3.0±1); glutarnate (+3.0±1); serine (+0.3); asparagine (+0.2); glutamine (+0.2); glycine (0); threonine (44); proline (−0.5±1); alanine (45); histidine −0.5); cysteine (−1.0); methionine (−1.3); valine 1.5); leucine (−1.8); isoleucine (−1.8); tyrosine (−2.3); phenylalanine (−2.5); tryptophan (−3.4).
  • It is understood that an amino acid can be substituted for another having a similar hydrophilicity value and still obtain a biologically equivalent and immunologically equivalent polypeptide. In such changes, the substitution of amino acids whose hydrophilicity values are within ±2 is preferred, those that are within ±1 are particularly preferred, and those within ±0.5 are even more particularly preferred.
  • As outlined above, amino acid substitutions are generally based on the relative similarity of the amino acid side-chain substituents, for example, their hydrophobicity, hydrophilicity, charge, size, and the like. Exemplary substitutions that take various of the foregoing characteristics into consideration are well known to those of skill in the art and include: arginine and lysine; glutarnate and aspartate; serine and threonine; glutamine and asparagine; and valine, leucine and isoleucine.
  • Aspects of the invention may be implemented in hardware or software, or a combination of both. However, preferably, the algorithms and processes of the invention are implemented in one or more computer programs executing on programmable computers each comprising at least one processor, at least one data storage system (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. Program code is applied to input data to perform the functions described herein and generate output information. The output information is applied to one or more output devices, in known fashion.
  • Each program may be implemented in any desired computer language (including machine, assembly, high level procedural, or object oriented programming languages) to communicate with a computer system. In any case, the language may be a compiled or interpreted language.
  • Each such computer program is preferably stored on a storage medium or device (e.g., ROM, CD-ROM, tape, or magnetic diskette) readable by a general or special purpose programmable computer, for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. The inventive system may also be considered to be implemented as a computer-readable storage medium, configured with a computer program, where the storage medium so configured causes a computer to operate in a specific and predefined manner to perform the functions described herein.
  • Thus, in another embodiment, the invention provides a computer program, stored on a computer-readable medium, for generating a target polynucleotide sequence. The computer program includes instructions for causing a computer system to: 1) identify an initiating polynucleotide sequence contained in the target polynucleotide sequence; 2) parse the target polynucleotide sequence into multiply distinct, partially complementary, oligonucleotides; and 3) control assembly of the target polynucleotide sequence by controlling the bi-directional extension of the initiating polynucleotide sequence by the sequential addition of partially complementary oligonucleotides resulting in a contiguous double-stranded polynucleotide. The computer program will contain an algorithm for parsing the sequence of the target polynucleotide by generating a set of oligonucleotides corresponding to a polypeptide sequence. The algorithm utilizes a polypeptide sequence to generate a DNA sequence using a specified codon table. The algorithm then generates a set of parsed oligonucleotides corresponding to the (+) and (−) strands of the DNA sequence in the following manner:
      • 1. The DNA sequence GENE[ ], an array of bases, is generated from the protein sequence AA[ ], an array of amino acids, using a specified codon table. An example of the codon table for E. coli type II codons, is listed below.
        • a. parameters
          • i. N Length of protein in amino acid residues
          • ii. L=3N Length of gene in DNA bases
          • iii. Q Length of each component oligonucleotide
          • iv. X=Q/2 Length of overlap between oligonucleotides
          • v. W=3N/Q Number of oligonucleotides in the F set
          • vi. Z=3N/Q+1 Number of oligonucleotides in the R set
          • vii. F[1:W] set of (+) strand oligonucleotides
          • viii. R[L:Z] set of (−) strand oligonucleotides
          • ix. AA[1:N] array of amino acid residues
          • x. GENE[1:L] array of bases comprising the gene
        • b. Obtain or design a protein sequence AA[ ] consisting of a list of amino acid residues.
        • c. Generate the DNA sequence, GENE[ ], from the protein sequence, AA[ ]
          • i. For I=1 to N
          • ii. Translate AA[J] from codon table generating GENE[I: I+2]
          • iii. I=I+3
          • iv. J=J+1
          • v. Go to ii
      • 2. Two sets of overlapping oligonucleotides are generated from GENE[ ]; F[ ] covers the (+) strand and R[ ] is a complementary, partially overlapping set covering the (−) strand.
        • a. Generate the F[ ] set of oligos
          • i. For I=1 to W
          • ii. F[I]=GENE [I:I+Q−1]
          • iii. I═I+Q
          • iv. Go to ii
        • b. Generate the R set of oligos
          • i. J=W
          • ii. For I=1 to W
          • iii. R[I]=GENE [W:W−Q]
          • iv. J=J−Q
          • v. Go to iii
        • c. Result is two set of oligos F[ ] and R[ ] of Q length
        • d. Generate the final two finishing oligos
          • i. S[1]=GENE [Q/2:1]
          • ii. S[2]=GENE [L−Q/2:L]
            Subsequently, oligonucleotide set assembly is established by the following algorithm:
  • Two sets of oligonucleotides F[1:W] R[1:Z] S[1:2]
      • 3. Step 1
        • a. For I=1 to W
        • b. Ligate F[I], F[I+1], R[I]; place in T[I]
        • c. Ligate F[I+2], R[I+1], R[I+2] T[I+1]
        • d. I=I+3
        • e. Go to b
      • 4. Step 2
        • a. Do the following until only a single reaction remains
          • i. For I=1 to W/3
          • ii. Ligate T[I], T[I+1]
          • iii. I=I+2
  • iv. Go to ii
    CODON TABLE (E. coli Class II preferred usage)
    PHE TTC
    SER TCT
    TYR TAC
    CYS TGG
    TER TGA
    TRP TGG
    ILE ATC
    MET ATG
    THR ACC
    LEU CTG
    PRO CCG
    HIS CAC
    GLN CAG
    ARG CGT
    VAL GTT
    ALA GCG
    ASN AAC
    LYS AAA
    ASP GAC
    GLU GAA
    GLY GGT
  • Algorithms of the invention useful for assembly of a target polynucleotide can further be described as Perl script as set forth below. ALGORITHM 1 provides a method for converting a protein sequence into a polynucleotide sequence using E. Coli codons:
    #$sequence is the protein sequence in single letter amino
    acid code
    #$seqlen is the length of the protein sequence
    #$amino acid is the individual amino acid in the sequence
    #$codon is the individual DNA triplet codon in the Gene
    sequence
    #$DNAsquence is the gene sequence in DNA bases
    #$baselen is the length of the DNA sequence in bases
    $seqlen = length($sequence);
    $baselen = $seqlen * 3;
    for ($n = 0; $n <= $seqlen; $n++)
    {
    $aminoacid = substr ($sequence,$n,1);
  • The following list provides the class II codon preference in Perl for E. coli
    if ($aminoacid eq “m”) {$codon = “ATG”;}
      elsif ($aminoacid eq “f”) {$codon = “TTC”;}
      elsif ($aminoacid eq “l”) {$codon = “CTG”;}
      elsif ($aminoacid eq “s”) {$codon = “TCT”;}
      elsif ($aminoacid eq “y”) {$codon = “TAC”;}
      elsif ($aminoacid eq “c”) {$codon = “TGC”;}
      elsif ($aminoacid eq “w”) {$codon = “TGG”;}
      elsif ($aminoacid eq “i”) {$codon = “ATC”;}
      elsif ($aminoacid eq “t”) {$codon = “ACC”;}
      elsif ($aminoacid eq “p”) {$codon = “CCG”;}
      elsif ($aminoacid eq “q”) {$codon = “CAG”;}
      elsif ($aminoacid eq “r”) {$codon = “CGT”;}
      elsif ($aminoacid eq “v”) {$codon = “GTT”;}
      elsif ($aminoacid eq “a”) {$codon = “GCG”;}
      elsif ($aminoacid eq “n”) {$codon = “AAC”;}
      elsif ($aminoacid eq “k”) {$codon = “AAA”;}
      elsif ($aminoacid eq “d”) {$codon = “GAC”;}
      elsif ($aminoacid eq “e”) {$codon = “GAA”;}
      elsif ($aminoacid eq “g”) {$codon = “GGT”;}
      elsif ($aminoacid eq “h”) {$codon = “CAC”;}
      else {$codon = “”};
    $DNAsequence = $DNAsequence + $codon;
  • ALGORITHM 2 provides a method for parsing a polynucleotide sequence into component forward and reverse oligonucleotides that can be reassembled into a complete target polynucleotide encoding a target polypeptide:
    #$oligoname is the identifier name for the list and for each
    component #oligonucleotide
    #$OL is the length of each component oligonucleotide
    #$Overlap is the length of the overlap in bases between each
    forward and each #reverse oligonucleotide
    #$sequence is the DNA sequence in bases
    #$seqlen is the length of the DNA sequence in bases
    #$bas is the individual base in a sequence
    #$forseq is the sequence of a forward oligonucleotide
    #$revseq is the sequence of a reverse oligonucleotide
    #$revcomp is the reverse complemented sequence of the gene
    #$oligonameF- [ ] is the list of parsed forward oligos
    #$oligonameR- [ ] is the list of parsed reverse oligos
    $Overlap = <STDIN>;
    $seqlen = length($sequence);
    #convert forward sequence to upper case if lower case
    $forseq = “”;
    for ($j = 0; $j <= seqlen−1; $j ++)
    {  $bas = substr($sequence,$j,1);
      if ($bas eq “a”) {$cfor = “A”;}
        elsif ($bas eq “t”) {$cfor = “T”;}
        elsif ($bas eq “c”) {$cfor = “C”;}
        elsif ($bas eq “g”) {$cfor = “G”;}
        elsif ($bas eq “A”) {$cfor = “A”;}
        elsif ($bas eq “T”) {$cfor = “T”;}
        elsif ($bas eq “C”) {$cfor = “C”;}
        elsif ($bas eq “G”) {$cfor = “G”;}
        else {$cfor = “X”};
      $forseq = $forseq.$cfor;
      print OUT “Sj \n”;
    }
  • The reverse complement of the sequence generated above is identified by:
    $revcomp = “”;
    for ($i = $seqlen−1; $i >= 0; $i−−)
    {  $base = substr($sequence,$i,1);
      if ($base eq “a”) {$comp = “T”;}
        elsif ($base eq “t”) {$comp = “A”;}
        elsif ($base eq “g”) {$comp = “C”;}
        elsif ($base eq “c”) {$comp = “G”;}
        elsif ($base eq “A”) {$comp = “T”;}
        elsif ($base eq “T”) {$comp = “A”;}
        elsif ($base eq “G”) {$comp = “C”;}
        elsif ($base eq “C”) {$comp = “G”;}
        else {$comp = “X”};
      $revcomp = $revcomp.$comp;
    }
    #now do the parsing
    #generate the forward oligo list
    print OUT “Forward oligos\n”;
    print “Forward oligos\n”;
    $r = 1;
    for ($i = 0; $i <= $seqlen −1; $i+=$OL)
    {  $oligo = substr($sequence,$i,$OL);
      print OUT “$oligname F- $r $oligo\n”;
      print “$oligname F- $r $oligo\n”;
      $r = $r + 1;
    }
    #generate the forward reverse list
    $r = 1;
    for ($i = $seqlen − $Overlap − $OL; $i >= 0; $i−=$OL)
    {
      print OUT “\n”;
      print “\n”;
      $oligo = substr($revcomp,$i,$OL);
      print OUT “$oligname R- $r $oligo”;
      print “$oligname R- $r $oligo”;
      $r = $r + 1;
    }
    #Rectify and print out the last reverse oligo consisting of
    1/2 from the beginning # of the reverse complement.
    $oligo = substr($revcomp,1,$Overlap);
    print OUT “$oligo\n”;
    print “$oligo\n”;
  • The invention further provides a computer-assisted method for synthesizing a target polynucleotide encoding a target polypeptide derived from a model sequence using a programmed computer including a processor, an input device, and an output device, by inputting into the programmed computer, through the input device, data including at least a portion of the target polynucleotide sequence encoding a target polypeptide. Subsequently, the sequence of at least one initiating polynucleotide present in the target polynucleotide sequence is determined and a model for synthesizing the target polynucleotide sequence is derived. The model is based on the position of the initiating sequence in the target polynucleotide sequence using overall sequence parameters necessary for expression of the target polypeptide in a biological system. The information is outputted to an output device which provides the means for synthesizing and assembling to target polynucleotide.
  • It is understood that any apparatus suitable for polynucleotide synthesis can be used in the present invention. Various non-limiting examples of apparatus, components, assemblies and methods are described below. For example, in one embodiment, it is contemplated that a nanodispensing head with up to 16 valves can be used to deposit synthesis chemicals in assembly vessels (FIG. 4). Chemicals can be controlled using a syringe pump from the reagent reservoir. Because of the speed and capability of the ink-jet dispensing system, synthesis can be made very small and very rapid. Underlying the reaction chambers is a set of assembly vessels linked to microchannels that will move fluids by microfluidics. The configuration of the channels will pool pairs and triplexes of oligonucleotides systematically using, for example, a robotic device. However, pooling can be accomplished using fluidics and without moving parts.
  • As shown in FIG. 5, oligonucleotide synthesis, oligonucleotide assembly by pooling and annealing, and ligation can be done using microfluidic mixing, resulting in the same set of critical triplex intermediates that serves as the substrate for annealing, ligation and oligonucleotide joining. DNA ligase and other components can be placed in the buffer fluid moving through the instrument microchambers. Thus, synthesis and assembly can be carried out in a highly controlled way in the same instrument.
  • As shown in FIG. 6, the pooling manifold can be produced from non-porous plastic and designed to control sequential pooling of oligonucleotides synthesized in arrays. Oligonucleotide parsing from a gene sequence designed in the computer can be programmed for synthesis where (+) and (−) strands are placed in alternating wells of the array. Following synthesis in this format, the 12 row sequences of the gene are directed into the pooling manifold that systematically pools three wells into reaction vessels forming the critical triplex structure. Following temperature cycling for annealing and ligation, four sets of triplexes are pooled into 2 sets of 6 oligonucleotide products, then 1 set of 12 oligonucleotide products. Each row of the synthetic array is associated with a similar manifold resulting in the first stage of assembly of 8 sets of assembled oligonucleotides representing 12 oligonucleotides each. As shown in FIG. 7, the second manifold pooling stage is controlled by a single manifold that pools the 8 row assemblies into a single complete assembly. Passage of the oligonucleotide components through the two manifold assemblies (the first 8 and the second single) results in the complete assembly of all 96 oligonucleotides from the array. The assembly module (FIG. 8) of Genewriter™ can include a complete set of 7 pooling manifolds produced using microfabrication in a single plastic block that sits below the synthesis vessels. Various configurations of the pooling manifold will allow assembly of 96,384 or 1536 well arrays of parsed component oligonucleotides.
  • The initial configuration is designed for the assembly of 96 oligonucleotides synthesized in a pre-defined array, composed of 48 pairs of overlapping 50 mers. Passage through the assembly device in the presence of DNA ligase and other appropriate buffer and chemical components, and with appropriate temperature controls on the device, will assembly these into a single 2400base double stranded gene assembly (FIG. 9).
  • The basic pooling device design can be made of Plexiglas™ or other type of co-polymer with microgrooves or microfluidic channels etched into the surface and with a temperature control element such as a Peltier circuit underlying the junction of the channels. This results in a microreaction vessel at the junction of two channels for 1) mixing of the two streams, 2) controlled temperature maintenance or cycling a the site of the junction and 3) expulsion of the ligated mixture from the exit channel into the next set of pooling and ligation chambers.
  • As shown in FIG. 11, the assembly platform design can consist of 8 synthesis microwell plates in a 96 well configuration, addressed with 16 channels of microdispensing. Below each plate is: 1) an evacuation manifold for removing synthesis components; and 2) an assembly manifold based on the schematic in FIG. 9 for assembling component oligonucleotides from each 96-well array. FIG. 12 shows a higher capacity assembly format using 1536-well microplates and capable of synthesis of 1536 component oligonucleotides per plate. Below each plate is: 1) an evacuation manifold for removing synthesis components; and 2) an assembly manifold assembly for assembling 1536 component oligonucleotides from each 1536-well array. Pooling and assembly strategies can be based on the concepts used for 96-well plates.
  • An alternative assembly format includes using surface-bound oligonucleotide synthesis rather than soluble synthesis on CPG glass beads (FIG. 13). In this configuration, oligonucleotides are synthesized with a hydrocarbon linker that allows attachment to a solid support. Following parsing of component sequences and synthesis, the synthesized oligonucleotides are covalently attached to a solid support such that the stabilizer is attached and the two ligation substrates added to the overlying solution. Ligation occurs as mediated by DNA ligase in the solution and increasing temperature above the Tm removes the linked oligonucleotides by thermal melting. As shown in FIG. 14 the systematic assembly on a solid support of a set of parsed component oligonucleotides can be arranged in an array with the set of stabilizer oligonucletoide attached. The set of ligation substrate oligonucleotides are placed in the solution and, systematic assembly is carried out in the solid phase by sequential annealing, ligation and melting which moves the growing DNA molecules across the membrane surface.
  • FIG. 15 shows an additional alternative means for oligonucleotide assembly, by binding the component oligonucleotides to a set of metal electrodes on a microelectronic chip, where each electrode can be controlled independently with respect to current and voltage. The array contains the set of minus strand oligonucleotides. Placing a positive change on the electrode will move by electrophoresis the component ligase substrate oligonucleotide onto the surface where annealing takes place. The presence of DNA ligase mediates covalent joining or ligation of the components. The electrode is then turned off or a negative charge is applied and the DNA molecule expulsed from the electrode. The next array element containing the next stabilizer oligonucleotide from the parsed set is turned on with a positive charge and a second annealing, joining and ligation with the next oligonucleotide in the set carried out. Systematic and repetitive application of voltage control, annealing, ligation and denaturation will result in the movement of the growing chain across the surface as well as assembly of the components into a complete DNA molecule.
  • The invention further provides methods for the automated synthesis of target polynucleotides. For example, a desired sequence can be ordered by any means of communication available to a user wishing to order such a sequence. A “user”, as used herein, is any entity capable of communicating a desired polynucleotide sequence to a server. The sequence may be transmitted by any means of communication available to the user and receivable by a server. The user can be provided with a unique designation such that the user can obtain information regarding the synthesis of the polynucleotide during synthesis. Once obtained, the transmitted target polynucleotide sequence can be synthesized by any method set forth in the present invention.
  • The invention further provides a method for automated synthesis of a polynucleotide, by providing a user with a mechanism for communicating a model polynucleotide sequence and optionally providing the user with an opportunity to communicate at least one desired modification to the model sequence. The invention envisions a user providing a model sequence and a desired modification to that sequence which results in the alteration of the model sequence. Any modification that alters the expression, function or activity of a target polynucleotide or encoded target polypeptide can be communicated by the user such that a modified polynucleotide or polypeptide is synthesized or expressed according to a method of the invention. For example, a model polynucleotide encoding a polypeptide normally expressed in a eukaryotic system can be altered such that the codons of the resulting target polynucleotide are conducive for expression of the polypeptide in a prokaryotic system. In addition, the user can indicate a desired modified activity of a polypeptide encoded by a model polynucleotide. Once provided, the algorithms and methods of the present invention can be used to synthesize a target polynucleotide encoding a target polypeptide believed to have the desired modified activity. The methods of the invention can be further utilized to express the target polypeptide and to screen for the desired activity. It is understood that the methods of the invention provide a means for synthetic evolution whereby any parameter of polynucleotide expression and/or polypeptide activity can be altered as desired.
  • Once the transmitted model sequence and desired modification are provided by the user, the data including at least a portion of the model polynucleotide sequence is inputted into a programmed computer, through an input device. Once inputted, the algorithms of the invention are used to determine the sequence of the model polynucleotide sequence containing the desired modification and resulting in a target polynucleotide containing the modification. Subsequently, the processor and algorithms of the invention is used to identify at least one initiating polynucleotide sequence present in the polynucleotide sequence. A target polynucleotide (i.e., a modified model polynucleotide) is identified and synthesized.
  • EXAMPLES
  • Nucleic Acid Synthesis Design Protocol
  • For the purposes of assembling a synthetic nucleic acid sequence encoding a target polypeptide, a model polypeptide sequence or nucleic acid sequence is obtained and analyzed using a suitable DNA analysis package, such as, for example, MacVector or DNA Star. If the target protein will be expressed in a bacterial system, for example, the model sequence can be converted to a sequence encoding a polypeptide utilizing E. coli preferred codons (i.e., Type I, Type II or Type II codon preference). The present invention provides the conversion programs Codon I, Codon II or Codon III. A nucleic acid sequence of the invention can be designed to accommodate any codon preference of any prokaryotic or eucaryotic organism.
  • In addition to the above codon preferences, specific promoter, enhancer, replication or drug resistance sequences can be included in a synthetic nucleic acid sequence of the invention. The length of the construction can be adjusted by padding to give a round number of bases based on about 25 to 100 bp synthesis. The synthesis of sequences of about 25 to 100 bp in length can be manufactured and assembled using the array synthesizer-system and may be used without further purification. For example, two 96-well plates containing 100-mers could give a 9600 bp construction of a target sequence.
  • Subsequent to the design of the oligonucleotides needed for assembly of the target sequence, the oligonucleotides are parsed using ParseOligo™, a proprietary computer program that optimizes nucleic acid sequence assembly. Optional steps in sequence assembly include identifying and eliminating sequences that may give rise to hairpins, repeats or other difficult sequences. The parsed oligonucleotide list is transferred to the Synthesizer driver software. The individual oligonucleotides are pasted into the wells and oligonucleotide synthesis is accomplished.
  • Assembly of Parsed Oligonucleotides Using a Two-Step PCR Reaction:
  • Obtain arrayed sets of parsed overlapping oligonucleotides, 50 bases each, with an overlap of about 25 base pairs (bp). The oligonucleotide concentration is from 250 nM (250 μM/ml). 50 base oligos give Tms from 75 to 85 degrees C., 6 to 10 od260, 11 to 15 nanomoles, 150 to 300 μg. Resuspend in 50 to 100 μl of H2O to make 250 nM/ml. Combine equal amounts of each oligonucleotide to final concentration of 250 μM (250 nM/ml). Add 1 μl of each to give 192 μl. Add 8 μl dH2O to bring up to 200 μl. Final concentration is 250 μM mixed oligos. Dilute 250-fold by taking 10 μl of mixed oligos and add to 1 ml of water. (1/100; 2.5 μM then take 1 μl of this and add to 24 μl 1×PCR mix. The PCR reaction includes:
      • 10 mM TRIS-HCl, pH 9.0
      • 2.2 mM MgCl2
      • 50 mM KCl
      • 0,2 mM each DNTP
      • 0.1% Triton X-100
        One U TaqI polymerase is added to the reaction. The reaction is thermoycled under the following conditions
  • a. Assembly
    i. 55 cycles of
    1. 94 degrees 30 s
    2. 52 degrees 30 s
    3. 72 degrees 30 s
  • Following assembly amplification, take 2.5 μl of this assembly mix and add to 100 μl of PCR mix. (40× dilution). Prepare outside primers by taking 1 μl of F1 (forward primer) and 1 μl of R96 (reverse primer) at 250 μM (250 nm/ml-0.250 nmole/μl) and add to the 100 μl PCR reaction. This gives a final concentration of 2.5 uM each oligo. Add 1 U Taq1 polymerase and thermocycle under the following conditions:
    35 cycles (or original protocol 23 cycles)
    94 degrees 30 s
    50 degrees 30 s
    72 degrees 60 s

    Extract with phenol/chloroform. Precipitate with ethanol. Resuspend in 10 μl of dH2O and analyze on an agarose gel.
    Assembly of Parsed Oligonucleotides Using Taq1 Ligation
  • Arrayed sets of parsed overlapping oligonucleotides of about 25 to 150 bases in length each, with an overlap of about 12 to 75 base pairs (bp), are obtained. The oligonucleotide concentration is from 250 nM (250 μM/ml). For example, 50 base oligos give Tms from 75 to 85 degrees C., 6 to 10 od260, 11 to 15 nanomoles, 150 to 300 μg. Resuspend in 50 to 100 ml of H2O to make 250 nM/ml.
  • Using a robotic workstation, equal amounts of forward and reverse oligos are combined pairwise. Take 10 μl of forward and 10 μl of reverse oligo and mix in a new 96-well v-bottom plate. This gives one array with sets of duplex oligonucleotides at 250μμ, according to pooling scheme Step 1 in Table 1. Prepare an assembly plate by taking 2 μl of each oligomer pair and adding to a fresh plate containing 100 μl of ligation mix in each well. This gives an effective concentration of 2.5 μM or 2.5 nM/ml. Transfer 20 μl of each well to a fresh microwell plate and add 1 μl of T4 polynucleotide kinase and 1 μl of 1 mM ATP to each well. Each reaction will have 50 pmoles of oligonucleotide and 1 nmole ATP. Incubate at 37 degrees C. for 30 minutes.
  • Initiate assembly according to Steps 2-7 of Table 1. Carry out pooling Step 2 mixing each successive well with the next. Add 1 μl of Taq1 ligase to each mixed well. Cycle once at 94 degrees for 30 sec; 52 degrees for 30 s; then 72 degrees for 10 minutes.
  • Carry out step 3 (Table 1) of pooling scheme and cycle according to the temperature scheme above. Carry out steps 4 and 5 of the pooling scheme and cycle according to the temperature scheme above. Carry out pooling scheme step 6 and take 10 μl of each mix into a fresh microwell. Carry out step 7 pooling scheme by pooling the remaining three wells. Reaction volumes will be:
    Initial plate has 20 ul per well.
    Step 2  20 ul + 20 ul = 40 ul
    Step
    3  80 ul
    Step
    4 160 ul
    Step
    5 230 ul
    Step
    6  10 ul + 10 ul = 20 ul
    Step
    7 20 + 20 + 20 = 60 ul final reaction
    volume
  • A final PCR amplification was then performed by taking 2 ul of final ligation mix and add to 20 ul of PCR mix containing 10 mM TRIS-HCl, pH 9.0, 2.2 mM MgCl2, 50 mM KCl, 0.2 mM each dNTP and 0.1% Triton X-100.
  • Prepare outside primers by taking 1 μl of F1 (forward primer) and 1 μl of R96 (reverse primer) at 250 μM (250 nm/ml-0.250 nmole/μl) and add to the 100 μl PCR reaction giving a final concentration of 2.5 uM each oligo. Add 1 U Taq1 polymerase and cycle for 35 cycles under the following conditions: 94 degrees for 30 s; 50 degrees for 30 s; and 72 degrees for 60 s. Extract the mixture with phenol/chloroform. Precipitate with ethanol. Resuspend in 10 μl of dH2O and analyze on an agarose gel.
    TABLE 1
    Pooling scheme for ligation assembly.
    Ligation method - Well pooling scheme
    STEP FROM TO
    1 All F All R
    2 A1 A2
    A3 A4
    A5 A6
    A7 A8
    A9 A10
    A11 A12
    B1 B2
    B3 B4
    B5 B6
    B7 B8
    B9 B10
    B11 B12
    C1 C2
    C3 C4
    C5 C6
    C7 C8
    C9 C10
    C11 C12
    D1 D2
    D3 D4
    D5 D6
    D7 D8
    D9 D10
    D11 D12
    E1 E2
    E3 E4
    E5 E6
    E7 E8
    E9 E10
    E11 E12
    F1 F2
    F3 F4
    F5 F6
    F7 F8
    F9 F10
    F11 F12
    G1 G2
    G3 G4
    G5 G6
    G7 G8
    G9 G10
    G11 G12
    H1 H2
    H3 H4
    H5 H6
    H7 H8
    H9 H10
    H11 H12
    3 A2 A4
    A6 A8
    A10 A12
    B2 B4
    B6 B8
    B10 B12
    C2 C4
    C6 C8
    C10 C12
    D2 D4
    D6 D8
    D10 D12
    E2 E4
    E6 E8
    E10 E12
    F2 F4
    F6 F8
    F10 F12
    G2 G4
    G6 G8
    G10 G12
    H2 H4
    H6 H8
    H10 H12
    4 A4 A8
    A12 B4
    B8 B12
    C4 C8
    C12 D4
    D8 D12
    E4 E8
    E12 F4
    F8 F12
    G4 G8
    G12 H4
    H8 H12
    5 A8 B4
    B12 C8
    D4 D12
    E8 F4
    F12 G8
    H4 H12
    6 B4 C8
    D12 F4
    G8 H12
    7 C8 F4 H12

    Assembly of Parsed Oligonucleotides Using Taq I Synthesis and Assembly
  • Arrayed sets of parsed overlapping oligonucleotides of about 25 to 150 bases in length each, with an overlap of about 12 to 75 base pairs (bp), are obtained. The oligonucleotide concentration is from 250 nM (250 μM/ml). 50 base oligos give Tms from 75 to 85 degrees C., 6 to 10 od260, 11 to 15 nanomoles, 150 to 300 μg. Resuspend in 50 to 100 ml of H2O to make 250 nM/ml.
  • The invention envisions using a robotic workstation to accomplish nucleic acid assembly. In the present example, two working plates containing forward and reverse oligonucleotides in a PCR mix at 2.5 mM are prepared and 1 μl of each oligo are added to 100 μl of PCR mix in a fresh microwell providing one plate of forward and one of reverse oligos in an array. Cycling assembly is then initiated as follows according to the pooling scheme outlined in Table 1. In the present example, 96 cycles of assembly can be accomplished according to this scheme.
  • Remove 2 μl of well F-E1 to a fresh well; remove 2 μl of R-E1 to a fresh well; add 18 μl of 1×PCR mix; add 1 U of Taq1 polymerase;
    Cycle once: 94 degrees 30 s
    52 degrees 30 s
    72 degrees 30 s

    Subsequently, remove 2 μl of well F-E2 to the reaction vessel; remove 2 μl of well R-D12 to the reaction vessel. Cycle once according to the temperatures above. Repeat the pooling and cycling according to the scheme outlined in Table 1 for about 96 cycles.
  • A PCR amplification is then performed by taking 2 □l of final reaction mix and adding it to 20 μl of a PCR mix comprising:
      • 10 mM TRIS-HCl, pH 9.0
      • 2.2 mM MgCl2
      • 50 mM KCl
      • 0.2 mM each DNTP
      • 0.1% Triton X-100
  • Outside primers are prepared by taking 1 μl of F1 and 1 μl of R96 at 250 mM (250 nm/ml-0.250 nmole/ml) and add to the 100 μl PCR reaction. This gives a final concentration of 2.5 μM each oligo. 1 U Taq1 polymerase is subsequently added and the reaction is cycled for about 23 to 35 cycles under the following conditions:
    94 degrees 30 s
    50 degrees 30 s
    72 degrees 60 s

    The reaction is subsequently extracted with phenol/chloroform, precipitated with ethanol and resuspend in 10 ml of dH2O for analysis on an agarose gel.
  • Equal amounts of forward and reverse oligos pairwise are added by taking 10 μl of forward and 10 μl of reverse oligo and mix in a new 96-well v-bottom plate. This provides one array with sets of duplex oligonucleotides at 250 mM, according to pooling scheme Step 1 in Table 1. An assembly plate was prepared by taking 2 μl of each oligomer pair and adding them to the plate containing 100 μl of ligation mix in each well. This gives an effective concentration of 2.5 μM or 2.5 nM/ml. About 20 μl of each well is transferred to a fresh microwell plate in addition to 11 μl of T4 polynucleotide kinase and 1 μl of 1 mM ATP. Each reaction will have 50 pmoles of oligonucleotide and 1 nmole ATP. Incubate at 37 degrees for 30 minutes.
  • Nucleic acid assembly was initiated according to Steps 2-7 of Table 1. Step 2 pooling is carried out by mixing each well with the next well in succession. 1 μl of Taq1 ligase to is added to each mixed well and cycled once as follows:
    94 degrees 30 sec
    52 degrees 30 s
    72 degrees 10 minutes
  • Step 3 of pooling scheme is carried out and cycled according to the temperature scheme above. Steps 4 and 5 of the pooling scheme are carried out and cycled according to the temperature scheme above. Carry out pooling scheme step 6 and take 10 μl of each mix into a fresh microwell. Step 7 pooling scheme is carried out by pooling the remaining three wells. The reaction volumes will be (initial plate has 20 μl per well):
    Step 2  20 μl + 20 μl = 40 μl
    Step
    3  80 μl
    Step
    4 160 μl
    Step
    5 230 μl
    Step
    6  10 μl + 10 μl = 20 μl
    Step
    7 20 + 20 + 20 = 60 μl final reaction
    volume

    A final PCR amplification is performed by taking 2 μl of the final ligation mix and adding it to 20 μl of PCR mix comprising:
      • 10 mM TRIS-HCl, pH 9.0
      • 2.2 mM MgCl2
      • 50 mM KCl
      • 0.2 mM each DNTP
      • 0.1% Triton X-100
  • Outside primers are prepared by taking 1 μl of F1 and 1 μl of R96 at 250 mM (250 nm/ml-0.250 nmole/ml) and adding them to the 100 μl PCR reaction giving a final concentration of 2.5 uM for each oligo. Subsequentlly, 1 U of Taq1 polymerase is added and cycled for about 23 to 35 cycles under the following conditions:
    94 degrees 30 s
    50 degrees 30 s
    72 degrees 60 s
  • The product is extracted with phenol/chloroform, precipitate with ethanol, resuspend in 10 μl of dH2O and analyzed on an agarose gel.
    TABLE 2
    Pooling scheme for assembly using Taql polymerase
    (also topoisomerase II).
    Step Forward oligo Reverse oligo
    1 F E 1 + R E 1 Pause
    2 F E 2 + R D 12 Pause
    3 F E 3 + R D 11 Pause
    4 F E 4 + R D 10 Pause
    5 F E 5 + R D 9 Pause
    6 F E 6 + R D 8 Pause
    7 F E 7 + R D 7 Pause
    8 F E 8 + R D 6 Pause
    9 F E 9 + R D 5 Pause
    10 F E 10 + R D 4 Pause
    11 F E 11 + R D 3 Pause
    12 F E 12 + R D 2 Pause
    13 F F 1 + R D 1 Pause
    14 F F 2 + R C 12 Pause
    15 F F 3 + R C 11 Pause
    16 F F 4 + R C 10 Pause
    17 F F 5 + R C 9 Pause
    18 F F 6 + R C 8 Pause
    19 F F 7 + R C 7 Pause
    20 F F 8 + R C 6 Pause
    21 F F 9 + R C 5 Pause
    22 F F 10 + R C 4 Pause
    23 F F 11 + R C 3 Pause
    24 F F 12 + R C 2 Pause
    25 F G 1 + R C 1 Pause
    26 F G 2 + R B 12 Pause
    27 F G 3 + R B 11 Pause
    28 F G 4 + R B 10 Pause
    29 F G 5 + R B 9 Pause
    30 F G 6 + R B 8 Pause
    31 F G 7 + R B 7 Pause
    32 F G 8 + R B 6 Pause
    33 F G 9 + R B 5 Pause
    34 F G 10 + R B 4 Pause
    35 F G 11 + R B 3 Pause
    36 F G 12 + R B 2 Pause
    37 F H 1 + R B 1 Pause
    38 F H 2 + R A 12 Pause
    39 F H 3 + R A 11 Pause
    40 F H 4 + R A 10 Pause
    41 F H 5 + R A 9 Pause
    42 F H 6 + R A 8 Pause
    43 F H 7 + R A 7 Pause
    44 F H 8 + R A 6 Pause
    45 F H 9 + R A 5 Pause
    46 F H 10 + R A 4 Pause
    47 F H 11 + R A 3 Pause
    48 F H 12 + R A 2 Pause
  • TABLE 3
    Alternate pooling scheme (initiating assembly from
    the 5′ or 3′ end)
     1. F-A1 → R-A1 denature, anneal, polymerase extension
     2. F-A2 → R-H12 denature, anneal, polymerase extension
     3. F-A3 → R-H11 denature, anneal, polymerase extension
     4. F-A4 → R-H10 denature, anneal, polymerase extension
     5. F-A5 → R-H9 denature, anneal, polymerase extension
     6. F-A6 → R-H8 denature, anneal, polymerase extension
     7. F-A7 → R-H7 denature, anneal, polymerase extension
     8. F-A8 → R-H6 denature, anneal, polymerase extension
     9. F-A9 → R-H5 denature, anneal, polymerase extension
    10. F-A10 → R-H4 denature, anneal, polymerase extension
    11. F-A11 → R-H3 denature, anneal, polymerase extension
    12. F-A12 → R-H2 denature, anneal, polymerase extension
    13. F-B1 → R-H1 denature, anneal, polymerase extension
    14. F-B2 → R-G12 denature, anneal, polymerase extension
    15. F-B3 → R-G11 denature, anneal, polymerase extension
    16. F-B4 → R-G10 denature, anneal, polymerase extension
    17. F-B5 → R-G9 denature, anneal, polymerase extension
    18. F-B6 → R-G8 denature, anneal, polymerase extension
    19. F-B7 → R-G7 denature, anneal, polymerase extension
    20. F-B8 → R-G6 denature, anneal, polymerase extension
    21. F-B9 → R-G5 denature, anneal, polymerase extension
    22. F-B10 → R-G4 denature, anneal, polymerase extension
    23. F-B11 → R-G3 denature, anneal, polymerase extension
    24. F-B12 → R-G2 denature, anneal, polymerase extension
    25. F-C1 → R-G1 denature, anneal, polymerase extension
    26. F-C2 → R-F12 denature, anneal, polymerase extension
    27. F-C3 → R-F11 denature, anneal, polymerase extension
    28. F-C4 → R-F10 denature, anneal, polymerase extension
    29. F-C5 → R-F9 denature, anneal, polymerase extension
    30. F-C6 → R-F8 denature, anneal, polymerase extension
    31. F-C7 → R-F7 denature, anneal, polymerase extension
    32. F-C8 → R-F6 denature, anneal, polymerase extension
    33. F-C9 → R-F5 denature, anneal, polymerase extension
    34. F-C10 → R-F4 denature, anneal, polymerase extension
    35. F-C11 → R-F3 denature, anneal, polymerase extension
    36. F-C12 → R-F2 denature, anneal, polymerase extension
    37. F-D1 → R-F1 denature, anneal, polymerase extension
    38. F-D2 → R-E12 denature, anneal, polymerase extension
    39. F-D3 → R-E11 denature, anneal, polymerase extension
    40. F-D4 → R-E10 denature, anneal, polymerase extension
    41. F-D5 → R-E9 denature, anneal, polymerase extension
    42. F-D6 → R-E8 denature, anneal, polymerase extension
    43. F-D7 → R-E7 denature, anneal, polymerase extension
    44. F-D8 → R-E6 denature, anneal, polymerase extension
    45. F-D9 → R-E5 denature, anneal, polymerase extension
    46. F-D10 → R-E4 denature, anneal, polymerase extension
    47. F-D11 → R-E3 denature, anneal, polymerase extension
    48. F-D12 → R-E2 denature, anneal, polymerase extension
    49. F-E1 → R-E1 denature, anneal, polymerase extension
    50. F-E2 → R-D12 denature, anneal, polymerase extension
    51. F-E3 → R-D11 denature, anneal, polymerase extension
    52. F-E4 → R-D10 denature, anneal, polymerase extension
    53. F-E5 → R-D9 denature, anneal, polymerase extension
    54. F-E6 → R-D8 denature, anneal, polymerase extension
    55. F-E7 → R-D7 denature, anneal, polymerase extension
    56. F-E8 → R-D6 denature, anneal, polymerase extension
    57. F-E9 → R-D5 denature, anneal, polymerase extension
    58. F-E10 → R-D4 denature, anneal, polymerase extension
    59. F-E11 → R-D3 denature, anneal, polymerase extension
    60. F-E12 → R-D2 denature, anneal, polymerase extension
    61. F-F1 → R-D1 denature, anneal, polymerase extension
    62. F-F2 → R-C12 denature, anneal, polymerase extension
    63. F-F3 → R-C11 denature, anneal, polymerase extension
    64. F-F4 → R-C10 denature, anneal, polymerase extension
    65. F-F5 → R-C9 denature, anneal, polymerase extension
    66. F-F6 → R-C8 denature, anneal, polymerase extension
    67. F-F7 → R-C7 denature, anneal, polymerase extension
    68. F-F8 → R-C6 denature, anneal, polymerase extension
    69. F-F9 → R-C5 denature, anneal, polymerase extension
    70. F-F10 → R-C4 denature, anneal, polymerase extension
    71. F-F11 → R-C3 denature, anneal, polymerase extension
    72. F-F12 → R-C2 denature, anneal, polymerase extension
    73. F-G1 → R-C1 denature, anneal, polymerase extension
    74. F-G2 → R-B12 denature, anneal, polymerase extension
    75. F-G3 → R-B11 denature, anneal, polymerase extension
    76. F-G4 → R-B10 denature, anneal, polymerase extension
    77. F-G5 → R-B9 denature, anneal, polymerase extension
    78. F-G6 → R-B8 denature, anneal, polymerase extension
    79. F-G7 → R-B7 denature, anneal, polymerase extension
    80. F-G8 → R-B6 denature, anneal, polymerase extension
    81. F-G9 → R-B5 denature, anneal, polymerase extension
    82. F-G10 → R-B4 denature, anneal, polymerase extension
    83. F-G11 → R-B3 denature, anneal, polymerase extension
    84. F-G12 → R-B2 denature, anneal, polymerase extension
    85. F-H1 → R-B1 denature, anneal, polymerase extension
    86. F-H2 → R-A12 denature, anneal, polymerase extension
    87. F-H3 → R-A11 denature, anneal, polymerase extension
    88. F-H4 → R-A10 denature, anneal, polymerase extension
    89. F-H5 → R-A9 denature, anneal, polymerase extension
    90. F-H6 → R-A8 denature, anneal, polymerase extension
    91. F-H7 → R-A7 denature, anneal, polymerase extension
    92. F-H8 → R-A6 denature, anneal, polymerase extension
    93. F-H9 → R-A5 denature, anneal, polymerase extension
    94. F-H10 → R-A4 denature, anneal, polymerase extension
    95. F-H11 → R-A3 denature, anneal, polymerase extension
    96. F-H12 → R-A2 denature, anneal, polymerase extension

    Assembly of Nucleic Acid Molecules
  • The nucleic acid molecules listed in Table 4 have been produced using the methods described herein. The features and characteristics of each nucleic acid molecule is also described in Table 4.
  • As described in Table 4, a synthetic plasmid of 4800 bp in length was assembled. The plasmid comprises 192 oligonucleotides (two sets of 96 overlapping 50 mers; 25 bp overlap). The plasmid is essentially pUC containing kanamycin resistance instead of ampicillin resistance. The synthetic plasmid also contains lux A and B genes from the Vibrio fisheri bacterial luciferase gene. The SynPuc19 plasmid is 2700 bp in length comprising a sequence essentially identical to pUC19 only shortened to precisely 2700 bp. Two sets of 96 50 mers were used to assemble the plasmid. The Synlux4 pUC19 plasmid was shortened and luxA gene was added. 54 100-mer oligonucleotides comprising two sets of 27 oligonucleotides were used to assemble the plasmid. The miniQE10 plasmid comprising 2400 bp was assembled using 48 50 mer oligonucleotides. MiniQE10 is an expression plasmid containing a 6×His tag and bacterial promoter for high-level polypeptide expression. MiniQE10 was assembled and synthesized using the Taq1 polymerase amplification method of the invention. The microQE plasmid is a minimal plasmid containing only an ampicillin gene, an origin of replication and a linker of pQE plasmids. MicroQE was assembled using either combinatoric ligation with 24 50-mers or with one tube PCR amplification. The SynFib1, SynFibB and SynFibG nucleic acid sequences are synthetic human fibrinogens manufactured using E. coli codons to optimize expression in a prokaryotic expression system.
    TABLE 4
    Synthetic nucleic acid molecules produced using
    the methods of the invention.
    Synthetic Plasmid 4800 192 50 circular F1-F96
    SynPUC/19 2700 192 50 circular F01-F96
    SynLux/4 2700 54 100 circular F1-27
    MiniQE10 2400 48 50 circular
    MicroQE 1200 24 50 circular MQEF-1,24
    Synfib1 1850 75 50 linear SFAF1-37
    pQE25 2400 96 25 circular F1-F48
    SynFibB 1500 60 59 50 mers linear FibbF1-30
    1 25 mer
    SynFibG 1350 54 53 50 mers linear FibgF1-27
    1 25 mer
  • It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.

Claims (4)

1-44. (canceled)
45. A computer-assisted method for synthesizing a target polynucleotide encoding a target polypeptide derived from a model sequence using a programmed computer including a processor, an input device, and an output device, comprising: a) inputting into the programmed computer, through the input device, data including at least a portion of the target polynucleotide sequence encoding a target polypeptide; b) determining, using the processor, the sequence of at least one initiating polynucleotide present in the target polynucleotide sequence c) selecting, using the processor, a model for synthesizing the target polynucleotide sequence based on the position of the initiating sequence in the target polynucleotide sequence using overall sequence parameters necessary for expression of the target polypeptide in a biological system; and d) outputting, to the output device, the results of the at least one determination.
46. The method of claim 45, further comprising predicting, using the processor, whether changing the model sequence to the target polynucleotide will have an effect on the target polypeptide encoded by the target polynucleotide based on at least one physical, structural or phylogenetic characteristic of the model sequence.
47-52. (canceled)
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Families Citing this family (75)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6670127B2 (en) * 1997-09-16 2003-12-30 Egea Biosciences, Inc. Method for assembly of a polynucleotide encoding a target polypeptide
US7563600B2 (en) 2002-09-12 2009-07-21 Combimatrix Corporation Microarray synthesis and assembly of gene-length polynucleotides
US7879580B2 (en) * 2002-12-10 2011-02-01 Massachusetts Institute Of Technology Methods for high fidelity production of long nucleic acid molecules
US7932025B2 (en) * 2002-12-10 2011-04-26 Massachusetts Institute Of Technology Methods for high fidelity production of long nucleic acid molecules with error control
US7041481B2 (en) 2003-03-14 2006-05-09 The Regents Of The University Of California Chemical amplification based on fluid partitioning
JP4093157B2 (en) * 2003-09-17 2008-06-04 株式会社日立製作所 Distributed inspection device and host inspection device
US20090317873A1 (en) * 2004-05-04 2009-12-24 Sridhar Govindarajan Design, synthesis and assembly of synthetic nucleic acids
US8825411B2 (en) 2004-05-04 2014-09-02 Dna Twopointo, Inc. Design, synthesis and assembly of synthetic nucleic acids
WO2007070726A2 (en) * 2005-12-16 2007-06-21 Gene Oracle, Inc. A gene synthesis kit
US20070231805A1 (en) * 2006-03-31 2007-10-04 Baynes Brian M Nucleic acid assembly optimization using clamped mismatch binding proteins
WO2007136834A2 (en) * 2006-05-19 2007-11-29 Codon Devices, Inc. Combined extension and ligation for nucleic acid assembly
WO2008027558A2 (en) * 2006-08-31 2008-03-06 Codon Devices, Inc. Iterative nucleic acid assembly using activation of vector-encoded traits
US7872120B2 (en) * 2007-08-10 2011-01-18 Venkata Chalapathi Rao Koka Methods for synthesizing a collection of partially identical polynucleotides
EP2285974A2 (en) 2008-05-14 2011-02-23 British Columbia Cancer Agency Branch Gene synthesis by convergent assembly of oligonucleotide subsets
US9764322B2 (en) 2008-09-23 2017-09-19 Bio-Rad Laboratories, Inc. System for generating droplets with pressure monitoring
US9156010B2 (en) 2008-09-23 2015-10-13 Bio-Rad Laboratories, Inc. Droplet-based assay system
US11130128B2 (en) 2008-09-23 2021-09-28 Bio-Rad Laboratories, Inc. Detection method for a target nucleic acid
US9417190B2 (en) 2008-09-23 2016-08-16 Bio-Rad Laboratories, Inc. Calibrations and controls for droplet-based assays
US9132394B2 (en) 2008-09-23 2015-09-15 Bio-Rad Laboratories, Inc. System for detection of spaced droplets
US9492797B2 (en) 2008-09-23 2016-11-15 Bio-Rad Laboratories, Inc. System for detection of spaced droplets
US9598725B2 (en) 2010-03-02 2017-03-21 Bio-Rad Laboratories, Inc. Emulsion chemistry for encapsulated droplets
US10512910B2 (en) 2008-09-23 2019-12-24 Bio-Rad Laboratories, Inc. Droplet-based analysis method
US8951939B2 (en) 2011-07-12 2015-02-10 Bio-Rad Laboratories, Inc. Digital assays with multiplexed detection of two or more targets in the same optical channel
US8158391B2 (en) 2009-05-06 2012-04-17 Dna Twopointo, Inc. Production of an α-carboxyl-ω-hydroxy fatty acid using a genetically modified Candida strain
EP2473618B1 (en) 2009-09-02 2015-03-04 Bio-Rad Laboratories, Inc. System for mixing fluids by coalescence of multiple emulsions
WO2011056872A2 (en) 2009-11-03 2011-05-12 Gen9, Inc. Methods and microfluidic devices for the manipulation of droplets in high fidelity polynucleotide assembly
WO2011066185A1 (en) 2009-11-25 2011-06-03 Gen9, Inc. Microfluidic devices and methods for gene synthesis
WO2011085075A2 (en) 2010-01-07 2011-07-14 Gen9, Inc. Assembly of high fidelity polynucleotides
US20110224086A1 (en) * 2010-03-09 2011-09-15 Jose Pardinas Methods and Algorithms for Selecting Polynucleotides For Synthetic Assembly
EP2556170A4 (en) 2010-03-25 2014-01-01 Quantalife Inc Droplet transport system for detection
JP2013524171A (en) 2010-03-25 2013-06-17 クァンタライフ・インコーポレーテッド Droplet generation for drop-based assays
EP4016086A1 (en) 2010-11-01 2022-06-22 Bio-Rad Laboratories, Inc. System for forming emulsions
WO2012064975A1 (en) 2010-11-12 2012-05-18 Gen9, Inc. Protein arrays and methods of using and making the same
WO2012078312A2 (en) 2010-11-12 2012-06-14 Gen9, Inc. Methods and devices for nucleic acids synthesis
DE102010056289A1 (en) 2010-12-24 2012-06-28 Geneart Ag Process for the preparation of reading frame correct fragment libraries
WO2012129187A1 (en) 2011-03-18 2012-09-27 Bio-Rad Laboratories, Inc. Multiplexed digital assays with combinatorial use of signals
JP2014512826A (en) 2011-04-25 2014-05-29 バイオ−ラド ラボラトリーズ インコーポレイテッド Methods and compositions for nucleic acid analysis
US20130059296A1 (en) 2011-08-26 2013-03-07 Gen9, Inc. Compositions and Methods For High Fidelity Assembly of Nucleic Acids
US9150853B2 (en) 2012-03-21 2015-10-06 Gen9, Inc. Methods for screening proteins using DNA encoded chemical libraries as templates for enzyme catalysis
WO2013155531A2 (en) 2012-04-13 2013-10-17 Bio-Rad Laboratories, Inc. Sample holder with a well having a wicking promoter
US10081807B2 (en) 2012-04-24 2018-09-25 Gen9, Inc. Methods for sorting nucleic acids and multiplexed preparative in vitro cloning
CA2877823A1 (en) 2012-06-25 2014-01-03 Gen9, Inc. Methods for nucleic acid assembly and high throughput sequencing
US9678948B2 (en) 2012-06-26 2017-06-13 International Business Machines Corporation Real-time message sentiment awareness
US9104656B2 (en) * 2012-07-03 2015-08-11 International Business Machines Corporation Using lexical analysis and parsing in genome research
US9690775B2 (en) 2012-12-27 2017-06-27 International Business Machines Corporation Real-time sentiment analysis for synchronous communication
US9460083B2 (en) 2012-12-27 2016-10-04 International Business Machines Corporation Interactive dashboard based on real-time sentiment analysis for synchronous communication
US10167366B2 (en) 2013-03-15 2019-01-01 Melior Innovations, Inc. Polysilocarb materials, methods and uses
TWI646230B (en) 2013-08-05 2019-01-01 扭轉生物科技有限公司 Re-synthesized gene bank
US10487323B2 (en) 2014-08-01 2019-11-26 The Regents Of The University Of California One-pot multiplex gene synthesis
CA2975855A1 (en) 2015-02-04 2016-08-11 Twist Bioscience Corporation Compositions and methods for synthetic gene assembly
US10669304B2 (en) 2015-02-04 2020-06-02 Twist Bioscience Corporation Methods and devices for de novo oligonucleic acid assembly
US9981239B2 (en) 2015-04-21 2018-05-29 Twist Bioscience Corporation Devices and methods for oligonucleic acid library synthesis
CA2998169A1 (en) 2015-09-18 2017-03-23 Twist Bioscience Corporation Oligonucleic acid variant libraries and synthesis thereof
CN108698012A (en) 2015-09-22 2018-10-23 特韦斯特生物科学公司 Flexible substrates for nucleic acid synthesis
US9895673B2 (en) 2015-12-01 2018-02-20 Twist Bioscience Corporation Functionalized surfaces and preparation thereof
AU2017315294B2 (en) 2016-08-22 2023-12-21 Twist Bioscience Corporation De novo synthesized nucleic acid libraries
JP6871364B2 (en) 2016-09-21 2021-05-12 ツイスト バイオサイエンス コーポレーション Nucleic acid-based data storage
GB2573069A (en) 2016-12-16 2019-10-23 Twist Bioscience Corp Variant libraries of the immunological synapse and synthesis thereof
KR20190119107A (en) 2017-02-22 2019-10-21 트위스트 바이오사이언스 코포레이션 Nucleic Acid Based Data Storage
CA3056388A1 (en) 2017-03-15 2018-09-20 Twist Bioscience Corporation Variant libraries of the immunological synapse and synthesis thereof
WO2018231864A1 (en) 2017-06-12 2018-12-20 Twist Bioscience Corporation Methods for seamless nucleic acid assembly
CN111566209A (en) 2017-06-12 2020-08-21 特韦斯特生物科学公司 Seamless nucleic acid assembly method
JP2020536504A (en) 2017-09-11 2020-12-17 ツイスト バイオサイエンス コーポレーション GPCR-coupled protein and its synthesis
GB2566986A (en) 2017-09-29 2019-04-03 Evonetix Ltd Error detection during hybridisation of target double-stranded nucleic acid
AU2018350212A1 (en) 2017-10-13 2020-04-23 Ribbon Biolabs Gmbh A novel method for synthesis of polynucleotides using a diverse library of oligonucleotides
GB2583590A (en) 2017-10-20 2020-11-04 Twist Bioscience Corp Heated nanowells for polynucleotide synthesis
EP3735459A4 (en) 2018-01-04 2021-10-06 Twist Bioscience Corporation Dna-based digital information storage
GB2590196A (en) 2018-05-18 2021-06-23 Twist Bioscience Corp Polynucleotides, reagents, and methods for nucleic acid hybridization
WO2020176680A1 (en) 2019-02-26 2020-09-03 Twist Bioscience Corporation Variant nucleic acid libraries for antibody optimization
EP3930753A4 (en) 2019-02-26 2023-03-29 Twist Bioscience Corporation Variant nucleic acid libraries for glp1 receptor
US20220162596A1 (en) 2019-04-10 2022-05-26 Ribbon Biolabs Gmbh A library of polynucleotides
US11332738B2 (en) 2019-06-21 2022-05-17 Twist Bioscience Corporation Barcode-based nucleic acid sequence assembly
US20230037041A1 (en) * 2019-12-30 2023-02-02 Yuandian Biolabs Co., Ltd. Apparatus and method for preparing nucleic acid sequences using enzyme
EP4091169A4 (en) * 2020-01-17 2024-02-14 Asklepios Biopharmaceutical Inc Systems and methods for synthetic regulatory sequence design or production
GB2619548A (en) * 2022-06-10 2023-12-13 Nunabio Ltd Nucleic acid and gene synthesis

Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5143854A (en) * 1989-06-07 1992-09-01 Affymax Technologies N.V. Large scale photolithographic solid phase synthesis of polypeptides and receptor binding screening thereof
US5198346A (en) * 1989-01-06 1993-03-30 Protein Engineering Corp. Generation and selection of novel DNA-binding proteins and polypeptides
US5663046A (en) * 1994-06-22 1997-09-02 Pharmacopeia, Inc. Synthesis of combinatorial libraries
US5686242A (en) * 1991-09-05 1997-11-11 Isis Pharmaceuticals, Inc. Determination of oligonucleotides for therapeutics, diagnostics and research reagents
US5714320A (en) * 1993-04-15 1998-02-03 University Of Rochester Rolling circle synthesis of oligonucleotides and amplification of select randomized circular oligonucleotides
US5733743A (en) * 1992-03-24 1998-03-31 Cambridge Antibody Technology Limited Methods for producing members of specific binding pairs
US5738996A (en) * 1994-06-15 1998-04-14 Pence, Inc. Combinational library composition and method
US5747334A (en) * 1990-02-15 1998-05-05 The University Of North Carolina At Chapel Hill Random peptide library
US5759799A (en) * 1995-04-06 1998-06-02 Bio Veto Test (S.A.R.L.) Marker for revealing contaminants and application method for performing an antibiogram carried out directly on a sample
US5770358A (en) * 1991-09-18 1998-06-23 Affymax Technologies N.V. Tagged synthetic oligomer libraries
US5783384A (en) * 1992-01-13 1998-07-21 President And Fellows Of Harvard College Selection of binding-molecules
US5804563A (en) * 1994-01-13 1998-09-08 The Trustees Of Columbia University In The City Of New York Synthetic receptors, libraries and uses thereof
US5807683A (en) * 1992-11-19 1998-09-15 Combichem, Inc. Combinatorial libraries and methods for their use
US5807754A (en) * 1995-05-11 1998-09-15 Arqule, Inc. Combinatorial synthesis and high-throughput screening of a Rev-inhibiting arylidenediamide array
US6136269A (en) * 1991-11-22 2000-10-24 Affymetrix, Inc. Combinatorial kit for polymer synthesis
US20010034580A1 (en) * 1998-08-25 2001-10-25 Jeffrey Skolnick Methods for using functional site descriptors and predicting protein function

Family Cites Families (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4652639A (en) 1982-05-06 1987-03-24 Amgen Manufacture and expression of structural genes
EP0316018A3 (en) * 1985-03-29 1989-07-26 Cetus Oncology Corporation Modification of dna sequences
GB8810400D0 (en) 1988-05-03 1988-06-08 Southern E Analysing polynucleotide sequences
AU3869289A (en) * 1988-07-14 1990-02-05 Baylor College Of Medicine Solid phase assembly and reconstruction of biopolymers
ATE143696T1 (en) * 1989-02-28 1996-10-15 Canon Kk PARTIALLY DOUBLE STRANDED OLIGONUCLEOTIDE AND METHOD FOR FORMING IT
US5837528A (en) * 1989-06-22 1998-11-17 Hoffmann La Roche, Inc. Bacterial strains which overproduce riboflavin
AU644619B2 (en) * 1989-12-21 1993-12-16 Advanced Technologies (Cambridge) Limited Modification of plant metabolism
AU658378B2 (en) * 1990-09-28 1995-04-13 F. Hoffmann-La Roche Ag Purified thermostable nucleic acid polymerase enzyme from thermosipho africanus
CA2097708A1 (en) 1990-12-06 1992-06-07 Stephen P. A. Fodor Very large scale immobilized polymer synthesis
ES2117050T3 (en) * 1991-06-27 1998-08-01 Genelabs Tech Inc SCREENING TEST FOR THE DETECTION OF MOLECULES OF UNION TO DNA.
US5981601A (en) * 1992-05-28 1999-11-09 Centre For Molecular Biology And Medicine Method for enhancing cellular bioenergy
WO1994012632A1 (en) * 1992-11-27 1994-06-09 University College London Improvements in nucleic acid synthesis by pcr
JPH09500526A (en) * 1993-06-14 1997-01-21 ベーアーエスエフ アクツィエンゲゼルシャフト Tight regulation of eukaryotic gene expression by the tetracycline-responsive promoter
US5591578A (en) * 1993-12-10 1997-01-07 California Institute Of Technology Nucleic acid mediated electron transfer
US6110457A (en) * 1995-12-08 2000-08-29 St. Louis University Live attenuated vaccines based on cp45 HPIV-3 strain and method to ensure attenuation in such vaccines
US6670127B2 (en) * 1997-09-16 2003-12-30 Egea Biosciences, Inc. Method for assembly of a polynucleotide encoding a target polypeptide
PT1538206E (en) * 1997-09-16 2010-04-12 Centocor Ortho Biotech Inc Method for the complete chemical synthesis and assembly of genes and genomes
US7321828B2 (en) 1998-04-13 2008-01-22 Isis Pharmaceuticals, Inc. System of components for preparing oligonucleotides
ATE465459T1 (en) * 1999-01-19 2010-05-15 Maxygen Inc THROUGH OLIGONUCLEOTIDE-MEDIATED NUCLEIC ACID RECOMBINATION
ATE456652T1 (en) * 1999-02-19 2010-02-15 Febit Holding Gmbh METHOD FOR PRODUCING POLYMERS
US7244560B2 (en) * 2000-05-21 2007-07-17 Invitrogen Corporation Methods and compositions for synthesis of nucleic acid molecules using multiple recognition sites

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5198346A (en) * 1989-01-06 1993-03-30 Protein Engineering Corp. Generation and selection of novel DNA-binding proteins and polypeptides
US5143854A (en) * 1989-06-07 1992-09-01 Affymax Technologies N.V. Large scale photolithographic solid phase synthesis of polypeptides and receptor binding screening thereof
US5747334A (en) * 1990-02-15 1998-05-05 The University Of North Carolina At Chapel Hill Random peptide library
US5686242A (en) * 1991-09-05 1997-11-11 Isis Pharmaceuticals, Inc. Determination of oligonucleotides for therapeutics, diagnostics and research reagents
US5789162A (en) * 1991-09-18 1998-08-04 Affymax Technologies N.V. Methods of synthesizing diverse collections of oligomers
US5770358A (en) * 1991-09-18 1998-06-23 Affymax Technologies N.V. Tagged synthetic oligomer libraries
US6136269A (en) * 1991-11-22 2000-10-24 Affymetrix, Inc. Combinatorial kit for polymer synthesis
US5783384A (en) * 1992-01-13 1998-07-21 President And Fellows Of Harvard College Selection of binding-molecules
US5733743A (en) * 1992-03-24 1998-03-31 Cambridge Antibody Technology Limited Methods for producing members of specific binding pairs
US5807683A (en) * 1992-11-19 1998-09-15 Combichem, Inc. Combinatorial libraries and methods for their use
US5714320A (en) * 1993-04-15 1998-02-03 University Of Rochester Rolling circle synthesis of oligonucleotides and amplification of select randomized circular oligonucleotides
US5804563A (en) * 1994-01-13 1998-09-08 The Trustees Of Columbia University In The City Of New York Synthetic receptors, libraries and uses thereof
US5738996A (en) * 1994-06-15 1998-04-14 Pence, Inc. Combinational library composition and method
US5663046A (en) * 1994-06-22 1997-09-02 Pharmacopeia, Inc. Synthesis of combinatorial libraries
US5759799A (en) * 1995-04-06 1998-06-02 Bio Veto Test (S.A.R.L.) Marker for revealing contaminants and application method for performing an antibiogram carried out directly on a sample
US5807754A (en) * 1995-05-11 1998-09-15 Arqule, Inc. Combinatorial synthesis and high-throughput screening of a Rev-inhibiting arylidenediamide array
US20010034580A1 (en) * 1998-08-25 2001-10-25 Jeffrey Skolnick Methods for using functional site descriptors and predicting protein function

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