Omega-3 fatty acid desaturase

Abstract

Recombinant expression of fat-1 gene of Caenorhabditis elegans in a wide variety of cells, including cells of Arabidopsis thaliana and Saccharomyces cerevisiae , produces a polypeptide having ω-3 desaturase activity.

What is claimed is:  
     
         1 . A cell comprising a recombinant FAT-1 polypeptide that desaturates an ω-6 fatty acid to a corresponding ω-3 fatty acid.  
     
     
         2 . The cell of  claim 1  wherein the ω-6 fatty acid has a carbon chain of at least 18 carbons.  
     
     
         3 . The cell of  claim 2  wherein the ω-6 fatty acid is a 20-carbon ω-6 fatty acid or a 22-carbon ω-6 fatty acid.  
     
     
         4 . The cell of  claim 1  wherein the ω-6 fatty acid has a double bond at one or more positions selected from the group consisting of Δ4, Δ5, Δ6, Δ7, and Δ8.  
     
     
         5 . The cell of  claim 1  having a proportion of ω-3 fatty acids that is at least 10% greater than an otherwise similar cell lacking the recombinant FAT-1 polypeptide.  
     
     
         6 . The cell of  claim 5  having a proportion of ω-3 fatty acids that is at least 20% greater than an otherwise similar cell lacking the recombinant FAT-1 polypeptide.  
     
     
         7 . The cell of  claim 6  having a proportion of ω-3 fatty acids that is at least 50% greater than an otherwise similar cell lacking the recombinant FAT-1 polypeptide.  
     
     
         8 . The cell of  claim 1  wherein the ω-6 fatty acid has a carbon chain of at least 20 carbons and at least 25% of the ω-6 fatty acid is desaturated to the corresponding ω-3 fatty acid.  
     
     
         9 . The cell of  claim 1  wherein the recombinant FAT-1 polypeptide has at least 60% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         10 . The cell of  claim 1  wherein the recombinant FAT-1 polypeptide has at least 70% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         11 . The cell of  claim 10  wherein the recombinant FAT-1 polypeptide has at least 80% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         12 . The cell of  claim 10  wherein the recombinant FAT-1 polypeptide has at least 90% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         13 . The cell of  claim 1  wherein the recombinant FAT-1 polypeptide has only conservative amino acid substitutions to the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         14 . The cell of  claim 1  wherein the recombinant FAT-1 polypeptide has 100% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         15 . The cell of  claim 1  wherein the recombinant FAT-1 polypeptide is encoded by a polynucleotide that comprises a sequence having at least 70%s nucleotide sequence identity with the fat-1 polynucleotide sequence of SEQ ID NO:1.  
     
     
         16 . The cell of  claim 15  wherein the polynucleotide comprises a sequence having at least 80% nucleotide sequence identity with the fat-1 polynucleotide sequence of SEQ ID NO:1.  
     
     
         17 . The cell of  claim 15  wherein the polynucleotide comprises a sequence having at least 90% nucleotide sequence identity with the fat-1 polynucleotide sequence of SEQ ID NO:1.  
     
     
         18 . The cell of  claim 15  wherein the polynucleotide comprises a sequence having 100% nucleotide sequence identity with the fat-1 polynucleotide sequence of SEQ ID NO:1.  
     
     
         19 . The cell of  claim 1  wherein the polypeptide is encoded by a polynucleotide comprising a full-length native fat-1 protein-coding region.  
     
     
         20 . A cell of  claim 1  of an organism selected from the group consisting of a bacterium, a cyanobacterium, a phytoplankton, an alga, a fungus, a plant, and an animal.  
     
     
         21 . A lipid from the cell of  claim 1 .  
     
     
         22 . The lipid of  claim 21  wherein at least 25% of an ω-6 fatty acid of the cell having a carbon chain of at least 20 carbons has been converted to a corresponding ω-3 fatty acid by the FAT-1 polypeptide.  
     
     
         23 . A transgenic plant comprising a fat-1 polynucleotide that is expressible in at least a part of the plant.  
     
     
         24 . The transgenic plant of  claim 23  wherein the fat-1 polynucleotide is expressible in a seed of the plant.  
     
     
         25 . A seed of the transgenic plant of  claim 23 .  
     
     
         26 . A lipid from the transgenic plant of  claim 23  that has a higher proportion of ω-3 fatty acids than a control lipid obtained from an otherwise similar plant lacking the fat-1 polynucleotide.  
     
     
         27 . A method of desaturating an ω-6 fatty acid to a corresponding ω-3 fatty acid comprising the steps of: 
 (a) providing a cell that comprises a recombinant FAT-1 polypeptide; and  
 (b) growing the cell under conditions under which the FAT-1 polypeptide desaturates an ω-6 fatty acid to produce a corresponding ω-3 fatty acid.  
 
     
     
         28 . The method of  claim 27  wherein the ω-6 fatty acid is an ω-6 fatty acid having a carbon chain of at least 18 carbons.  
     
     
         29 . The method of  claim 28  wherein the ω-6 fatty acid is a 20-carbon ω-6 fatty acid or a 22-carbon ω-6 fatty acid.  
     
     
         30 . The method of  claim 27  wherein the ω-6 fatty acid comprises a double bond at one or more positions selected from the group consisting of Δ4, Δ5, Δ6, Δ7, and Δ8.  
     
     
         31 . The method of  claim 27  wherein the recombinant polypeptide has at least 60% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         32 . The method of  claim 27  wherein the recombinant polypeptide has at least 70% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         33 . The method of  claim 32  wherein the recombinant polypeptide has at least 80% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         34 . The method of  claim 32  wherein the recombinant polypeptide has at least 90% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         35 . The method of  claim 32  wherein the recombinant polypeptide has only conservative amino acid substitutions to the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         36 . The method of  claim 32  wherein the recombinant polypeptide has 100% amino acid sequence identity with the FAT-1 polypeptide of SEQ ID NO:1.  
     
     
         37 . The method of  claim 27  wherein the FAT-1 polypeptide is encoded by a recombinant polynucleotide that comprises a sequence having at least 70% nucleotide sequence identity with the fat-1 polynucleotide sequence of SEQ ID NO:1.  
     
     
         38 . The method of  claim 37  wherein the polynucleotide comprises a sequence having at least 80% nucleotide sequence identity with the fat-1 polynucleotide sequence of SEQ ID NO:1.  
     
     
         39 . The method of  claim 37  wherein the polynucleotide comprises a sequence having at least 90% nucleotide sequence identity with the fat-1 polynucleotide sequence of SEQ ID NO:1.  
     
     
         40 . The method of  claim 37  wherein the polynucleotide comprises a sequence having 100% nucleotide sequence identity with the fat-1 polynucleotide sequence of SEQ ID NO:1.  
     
     
         41 . The method of  claim 27  wherein the polypeptide is encoded by a polynucleotide that comprises a full-length native fat-1 protein-coding region.  
     
     
         42 . A method of  claim 27  wherein the cell is a cell of an organism selected from the group consisting of a bacterium, a cyanobacterium, a phytoplankton, an alga, a fungus, a plant, and an animal.  
     
     
         43 . The method of  claim 42  wherein the cell is a plant cell.  
     
     
         44 . The method of  claim 42  wherein the cell is a yeast cell.  
     
     
         45 . A method of producing a lipid comprising an ω-3 fatty acid comprising the steps of: 
 (a) providing a lipid that comprises an ω-6 fatty acid; and  
 (b) desaturating at least some of the ω-6 fatty acid to a corresponding ω-3 fatty acid with a recombinant FAT-1 polypeptide.  
 
     
     
         46 . The method of  claim 45  wherein the lipid comprises an ω-6 fatty acid having a carbon chain of at least 20 carbons, the method comprising desaturating at least 25% of the ω-6 fatty acid to the corresponding ω-3 fatty acid.  
     
     
         47 . The method of  claim 45  comprising the step of expressing a recombinant fat-1 polynucleotide in a cell comprising the lipid, thereby producing the recombinant FAT-1 polypeptide in the cell.