Methods for generating polynucleotides having desired characteristics by iterative selection and recombination
First Claim
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1. A method for introducing one or more mutations into a template double-stranded polynucleotide, wherein the template double-stranded polynucleotide has been cleaved into double-stranded random fragments of a desired size, comprising:
- a) adding to the resultant population of double-stranded fragments one or more single or double-stranded oligonucleotides, wherein said oligonucleotides comprise an area of identity and an area of heterology to the template polynucleotide;
b) denaturing the resultant mixture of double-stranded random fragments and oligonucleotides into single-stranded fragments;
c) incubating the resultant population of single-stranded fragments with a polymerase under conditions which result in the annealing of said single-stranded fragments at regions of identity between the single-stranded fragments and formation of a mutagenized double-stranded polynucleotide; and
d) repeating steps (b) and (c).
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Abstract
A method for DNA reassembly after random fragmentation, and its application to mutagenesis of nucleic acid sequences by in vitro or in vivo recombination is described. In particular, a method for the production of nucleic acid fragments or polynucleotides encoding mutant proteins is described. The present invention also relates to a method of repeated cycles of mutagenesis, shuffling and selection which allow for the directed molecular evolution in vitro or in vivo of proteins.
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Citations
40 Claims
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1. A method for introducing one or more mutations into a template double-stranded polynucleotide, wherein the template double-stranded polynucleotide has been cleaved into double-stranded random fragments of a desired size, comprising:
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a) adding to the resultant population of double-stranded fragments one or more single or double-stranded oligonucleotides, wherein said oligonucleotides comprise an area of identity and an area of heterology to the template polynucleotide;
b) denaturing the resultant mixture of double-stranded random fragments and oligonucleotides into single-stranded fragments;
c) incubating the resultant population of single-stranded fragments with a polymerase under conditions which result in the annealing of said single-stranded fragments at regions of identity between the single-stranded fragments and formation of a mutagenized double-stranded polynucleotide; and
d) repeating steps (b) and (c). - View Dependent Claims (2, 3, 4, 5)
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6. A method of producing recombinant proteins having biological activity comprising:
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a) treating a sample comprising double-stranded template polynucleotides encoding a wild-type protein under conditions which provide for the cleavage of said template polynucleotides into random double-stranded fragments having a desired size;
b) adding to the resultant population of random fragments one or more single or double-stranded oligonucleotides, wherein said oligonucleotides comprise areas of identity and areas of neterology to the template polynucleotide;
c) denaturing the resultant mixture of double-stranded random fragments and oligonucleotides into single-stranded fragments;
d) incubating the resultant population of single-stranded fragments with a polymerase under conditions which result in the annealing of said single-stranded fragments at the areas of identity and formation of a mutagenized double-stranded polynucleotide;
e) repeating steps (c) and (d); and
f) expressing the recombinant protein from the mutagenized double-stranded polynucleotide. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method for obtaining a chimeric polynucleotide comprising:
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a) treating a sample comprising different double-stranded template polynucleotides wherein said different template polynucleotides contain areas of identity and areas of heterology under conditions which provide for the cleavage of said template polynucleotides into random double-stranded fragments of a desired size;
b) denaturing the resultant random double-stranded template fragments contained in the treated sample produced by step (a) into single-stranded fragments;
c) incubating the resultant single-stranded fragments with polymerase under conditions which provide for the annealing of the target single-stranded fragments at the areas of identity and the formation of a chimeric double-stranded polynucleotide sequence comprising template polynucleotide sequences; and
d) repeating steps (b) and (c) as desired. - View Dependent Claims (13, 14, 15, 16)
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17. A method of replicating a template polynucleotide which method comprises combining in vitro single-stranded template polynucleotides with small random single-stranded fragments resulting from the cleavage and denaturation of the template polynucleotide, and incubating said mixture of nucleic acid fragments in the presence of a nucleic acid polymerase under conditions wherein a population of double-stranded template polynucleotides is formed.
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18. A method for generating libraries of displayed peptides or displayed antibodies suitable for affinity interaction screening or phenotypic screening, the method comprising:
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(1) obtaining a first plurality of selected library members comprising a displayed peptide or displayed antibody and an associated polynucleotide encoding said displayed peptide or displayed antibody, and obtaining said associated polynucleotides or copies thereof wherein said associated polynucleotides comprise a region of substantially identical sequence, and (2) pooling and fragmenting said associated polynucleotides or copies to form fragments thereof under conditions suitable for PCR amplification, performing PCR amplification, and thereby homologously recombining said fragments to form a shuffled pool of recombined polynucleotides, whereby a substantial fraction of the recombined polynucleotides of said shuffled pool are not present in the first plurality of selected library members. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for generating libraries of displayed peptides or displayed antibodies suitable for affinity interaction screening or phenotypic screening, the method comprising:
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(1) obtaining a first plurality of selected library members comprising a displayed peptide or displayed antibody and an associated polynucleotide encoding said displayed peptide or displayed antibody, and obtaining said associated polynucleotides or copies thereof wherein said associated polynucleotides comprise a region of substantially identical sequence, and (2) cloning or amplifying said associated polynucleotides or copies on episomally replicable vectors and transferring a multiplicity of said vectors into a cell and homologously recombined to form shuffled library members in vivo. - View Dependent Claims (28, 29)
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30. A method for generating libraries of displayed antibodies suitable for affinity interaction screening, the method comprising:
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(1) obtaining a first plurality of selected library members comprising a displayed antibody and an associated polynucleotide encoding said displayed antibody, and obtaining said associated polynucleotides or copies thereof, wherein said associated polynucleotides comprise a region of substantially identical variable region framework sequence, and (2) pooling and fragmenting said associated polynucleotides or copies to form fragments thereof under conditions suitable for PCR amplification, performing PCR amplification, and thereby homologously recombining said fragments to form a shuffled pool of recombined polynucleotides comprising novel combinations of CDRs, whereby a substantial fraction of the recombined polynucleotides of said shuffled pool comprise CDR combinations are not present in the first plurality of selected library members. - View Dependent Claims (31, 32)
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- 33. A method for generating an enhanced GFP protein and polynucleotides encoding same, comprising performing DNA shuffling on a GFP encoding expression vector and selecting or screening for variants having an enhanced desired property.
- 36. An enhanced GFP protein comprising a point mutation as compared to wildtype sequence outside the chromophore region comprising amino acids 64-69.
Specification