# US 5,705,391 A · Modified acyl-ACP desaturase > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,391 A - Document ID: US5705391A - Status: Granted - Kind: A - Application number: 08/689,823 - Filed: 1996-08-14 - Granted: 1998-01-06 - Earliest claimed: 1996-08-14 - Assignees: Associated Universities, Inc. - Inventors: Edgar B. Cahoon; John Shanklin; Ylva Lindgvist; Gunter Schneider - Web page: https://patentgrep.com/patent/US5705391A ## CPC - C12N 9/0083: {Miscellaneous (1.14.99)} - C12N 15/8247: {involving modified lipid metabolism, e.g. seed oil composition} - C07K 2319/00: Fusion polypeptide - C12N: MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA (microbiological testing media C12Q1/00) - C07K: PEPTIDES (peptides in foodstuffs A23; obtaining protein compositions for foodstuffs, working-up proteins for foodstuffs A23J; preparations for medicinal purposes A61K; peptides containing beta-lactam rings C07D; cyclic dipeptides not having in their molecule any other peptide link than those which form their ring, e.g. piperazine-2,5-diones, C07D; ergot alkaloids of the cyclic peptide type C07D519/02; macromolecular compounds having statistically distributed amino acid units in their molecules, i.e. when the preparation does not provide for a specific; but for a random sequence of the amino acid units, homopolyamides and block copolyamides derived from amino acids C08G69/00; macromolecular products derived from proteins C08H1/00; preparation of glue or gelatine C09H; single cell proteins, enzymes C12N; genetic engineering processes for obtaining peptides C12N15/00; compositions for measuring or testing processes involving enzymes C12Q; investigation or analysis of biological material G01N33/00) ## Abstract Disclosed is a methods for modifying the chain length and double bond positional specificities of a soluble plant fatty acid desaturase. More specifically, the method involves modifying amino acid contact residues in the substrate binding channel of the soluble fatty acid desaturase which contact the fatty acid. Specifically disclosed is the modification of an acyl-ACP desaturase. Amino acid contact residues which lie within the substrate binding channel are identified, and subsequently replaced with different residues to effect the modification of activity. ## Claims ### Claim 1 A nucleic acid sequence encoding a mutant acyl-ACP desaturase which is characterized by the ability to catalyze desaturation of a first fatty acid and a second fatty acid, the first and second fatty acids differing in their chain length, the desaturation rates of both the first and second fatty acids differing by no more than about 4-fold, the nucleic acid sequence encoding the mutant acyl-ACP desaturase being characterized by a point mutation at an amino acid contact residue in the substrate binding channel, the nucleic acid sequence being further characterized as having a sufficient degree of amino acid identity with the amino acid sequence of Ricinus communis .DELTA..sup.9 desaturase to enable statistically significant sequence alignment with the Ricinus communis .DELTA..sup.9 desaturase. ### Claim 2 (depends on 1) The nucleic acid sequence of claim 1 wherein the point mutation is introduced into wild-type Ricinus communis .DELTA..sup.9 desaturase at one or more amino acid contact residues selected from the group consisting of residues 114, 115, 117, 118, 179, 181, 188 and 189. ### Claim 3 A DNA expression construct comprising, in expressible form, a nucleic acid sequence encoding a mutant acyl-ACP desaturase which is characterized by the ability to catalyze desaturation of a first fatty acid and a second fatty acid, the first and second fatty acids differing in their chain length, the desaturation rates of both the first and second fatty acids differing by no more than about 4-fold, the nucleic acid sequence encoding the mutant acyl-ACP desaturase being characterize by a point mutation at an amino acid contact residue in the substrate binding channel, the nucleic acid sequence being further characterized as having a sufficient degree of amino acid identity with the amino acid sequence of Ricinus communis .DELTA..sup.9 desaturase to enable statistically significant sequence alignment with the Ricinus communis .DELTA..sup.9 desaturase. ### Claim 4 (depends on 3) The DNA expression construct of claim 3 wherein the point mutation is introduced into wild-type Ricinus communis .DELTA..sup.9 desaturase at one or more amino acid contact residues selected from the group consisting of residues 114, 115, 117, 118, 179, 181, 188 and 189. ### Claim 5 A cell transformed with a DNA expression construct comprising, in expressible form, a nucleic acid sequence encoding a mutant acyl-ACP desaturase which is characterized by the ability to catalyze desaturation of a first fatty acid and a second fatty acid, the first and second fatty acids differing in their chain length, the desaturation rates of both the first and second fatty acids differing by no more than about 4-fold, the nucleic acid sequence encoding the mutant acyl-ACP desaturase being characterized by a point mutation at an amino acid contact residue in the substrate binding channel, the nucleic acid sequence being further characterized as having a sufficient degree of amino acid identity with the amino acid sequence of Ricinus communis .DELTA..sup.9 desaturase to enable statistically significant sequence alignment with the Ricinus communis .DELTA..sup.9 desaturase. ### Claim 6 (depends on 5) The cell of claim 5 wherein the point mutation is introduced into wild-type Ricinus communis .DELTA..sup.9 desaturase at one or more amino acid contact residues selected from the group consisting of residues 114, 115, 117, 118, 179, 181, 188 and 189. ### Claim 7 (depends on 5) The cell of claim 5 which is a prokaryotic cell. ### Claim 8 (depends on 5) The cell of claim 5 which is a eukaryotic cell. ### Claim 9 (depends on 8) The cell of claim 8 which is a plant cell.