Monovalent phage display
First Claim
1. A method for selecting novel binding polypeptides comprising:
- (a) constructing a replicable expression vector comprising a transcription regulatory element operably linked to a gene fusion encoding a fusion protein wherein the gene fusion comprises a first gene encoding a polylpeptide, and a second gene encoding at least a portion of a phage coat protein;
(b) mutating the vector at one or more selected positions within the first gene thereby forming a family of related plasmids;
(c) transforming suitable host cells with the plasmids;
(d) infecting the transformed host cells with an amount of a helper phage having a gene encoding the phage coat protein sufficient to produce recombinant phagemid particles wherein no more than a minor amount of phagemid particles display more than one copy of the fusion protein on the surface of the particle;
(e) culturing the transformed infected host cells under conditions suitable for forming recombinant phagemid particles containing at least a portion of the plasmid and capable of transforming the host cells, the conditions adjusted so that no more than a minor amount of phagemid particles display one or more copies of the fusion protein on the surface of the particle;
(f) contacting the phagemid particles with a target molecule so that at least a portion of the phagemid particles bind to the target molecule; and
(g) separating the phagemid particles that bind from those that do not.
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Abstract
A method for selecting novel proteins such as growth hormone and antibody fragment variants having altered binding properties for their respective receptor molecules is provided. The method comprises fusing a gene encoding a protein of interest to the carboxy terminal domain of the gene III coat protein of the filamentous phage M13. The gene fusion is mutated to form a library of structurally related fusion proteins that are expressed in low quantity on the surface of a phagemid particle. Biological selection and screening are employed to identify novel ligands useful as drug candidates. Disclosed are preferred phagemid expression vectors and selected human growth hormone variants.
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Citations
73 Claims
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1. A method for selecting novel binding polypeptides comprising:
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(a) constructing a replicable expression vector comprising a transcription regulatory element operably linked to a gene fusion encoding a fusion protein wherein the gene fusion comprises a first gene encoding a polylpeptide, and a second gene encoding at least a portion of a phage coat protein; (b) mutating the vector at one or more selected positions within the first gene thereby forming a family of related plasmids; (c) transforming suitable host cells with the plasmids; (d) infecting the transformed host cells with an amount of a helper phage having a gene encoding the phage coat protein sufficient to produce recombinant phagemid particles wherein no more than a minor amount of phagemid particles display more than one copy of the fusion protein on the surface of the particle; (e) culturing the transformed infected host cells under conditions suitable for forming recombinant phagemid particles containing at least a portion of the plasmid and capable of transforming the host cells, the conditions adjusted so that no more than a minor amount of phagemid particles display one or more copies of the fusion protein on the surface of the particle; (f) contacting the phagemid particles with a target molecule so that at least a portion of the phagemid particles bind to the target molecule; and (g) separating the phagemid particles that bind from those that do not. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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- 30. A group of phagemid particles, each particle comprising a replicable expression vector comprising a transcription regulatory element operably linked to a gene fusion encoding a fusion protein wherein the gene fusion comprises a first gene encoding a polypeptide, and a second gene encoding at least a portion of a phage coat protein, wherein a DNA tripler codon encoding an mRNA suppressible terminator codon selected from UAG, UAA and UGA is inserted between the fused ends of the first and second genes, or is substituted for an amino acid encoding triplet codon adjacent to the gene fusion junction, wherein no more than a minor amount of phagemid particles in said group display one or more copies of the fusion protein on the surface of the particle.
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44. A method for selecting novel binding polypeptides comprising:
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(a) constructing a replicable expression vector comprising a transcription regulatory element operably linked to DNA encoding a protein of interest containing one or more subunits, wherein the DNA encoding at least one of the subunits is fused to the DNA encoding at least a portion of a phage coat protein; (b) mutating the DNA encoding the protein of interest at one or more selected positions thereby forming a family of related vectors; (c) transforming suitable host cells with the vectors; (d) infecting the transformed host cells with a helper phage having a gene encoding the phage coat protein,; (e) culturing the transformed infected host cells under conditions suitable for forming capable of transforming the host, the conditions adjusted so that no more than a minor amount of phagemid particles display one or more copies of the fusion protein on the surface of the particle; (f) contacting the phagemid particles with a target molecule so that at least a portion of the phagemid particles bind to the target molecule; and (g) separating the phagemid particles that bind from those that do not. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52)
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53. A method for selecting novel binding polypeptides comprising:
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(a) constructing a replicable expression vector comprising a transcription regulatory element operably linked to a gene fusion encoding a fusion protein wherein the gene fusion comprises a first gene encoding a polypeptide operably connected to a linking amino acid sequence, and second gene encoding at least a portion of a phage coat protein; (b) mutating the vector at one or more selected positions within the amino acid linking sequence of the first gene thereby forming a family of related plasmids; (c) transforming suitable host cells with the plasmids; (d) infecting the transformed host cells with a helper phage having a gene encoding the phage coat protein; (e) culturing the transformed infected host cells under conditions suitable for forming recombinant phagemid particles containing at least a portion of the plasmid and capable of transforming the host, the conditions adjusted so that no more than a minor amount of phagemid particles display one or more copies of the fusion protein on the surface of the particle; (f) contacting the phagemid particles with a target molecule so that at least a portion of the phagemid particles bind to the target molecule; and (g) contacting the bound phagemid particles with a protease capable of hydrolyzing the linking amino acid sequence of at least a portion of the bound phagemid particles, and (h) isolating the hydrolyzed phagemid particles. - View Dependent Claims (54, 55, 56, 57)
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58. A method for selecting novel binding polypeptides comprising:
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(a) constructing a replicable expression vector comprising a transcription regulatory element operably linked to a gene fusion encoding a fusion protein wherein the gene fusion comprises a first gene encoding a polypeptide, and a second gene encoding at least a portion of a phage coat protein, wherein said coat protein is M13 phage gene III coat protein; (b) mutating the vector at one or more selected positions within the first gene thereby forming a family of related plasmids; (c) transforming suitable host cells with the plasmids; (d) infecting the transformed host cells with a helper phage having a gene encoding the phage coat protein, wherein the helper phage is M13KO7; (e) culturing the transformed infected host cells under conditions suitable for forming recombinant phagemid particles containing at least a portion of the plasmid and capable of transforming the host, the conditions adjusted so that no more than a minor amount of phagemid particles display one or more copies of the fusion protein on the surface of the particle; (f) contacting the phagemid particles with a target molecule so that at least a portion of the phagemid particles bind to the target molecule; and (g) separating the phagemid particles that bind from those that do not. - View Dependent Claims (59, 60, 61, 62, 63)
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- 64. A group of phagemid particles, each particle comprising a replicable expression vector comprising a transcription regulatory element operably linked to a gene fusion encoding a fusion protein wherein the gene fusion comprises a first gene encoding a polypeptide, and a second gene encoding at least a portion of a phage coat protein, wherein no more than a minor amount of phagemid particles in said group display one or more copies of the fusion protein on the surface of the particle.
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68. A method for selecting novel binding polypeptides comprising steps of:
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(a) constructing a family of variant replicable plasmids comprising a transcription regulatory element operably linked to a gene fusion encoding a fusion protein, wherein the gene fusion comprises a first gene encoding a polypeptide and a second gene encoding at least a portion of a phage coat protein, wherein the variant replicable plasmids comprise variant first genes encoding variant polypeptides; (b) transforming suitable host cells with the plasmids; (c) infecting the transformed host cells with an amount of helper phage encoding the phage coat protein sufficient to produce recombinant phagemid particles wherein no more than about 20 percent of the phagemid particles display one or more copies of the fusion protein on the surface of the phagemid particles; (d) culturing the transformed infected host cells under conditions suitable for forming recombinant phagemid particles containing at least a portion of the plasmid and capable of transforming the host cells; (e) contacting the recombinant phagemid particles with a target molecule so that at least a portion of the phagemid particles bind to the target molecule; and (f) separating phagemid particles that bind to the target molecule from those that do not bind. - View Dependent Claims (69, 70, 71, 72, 73)
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Specification