Identification of an Animal ω -3 Fatty Acid Desaturase by Heterologous Expression in Arabidopsis

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 94; no. 4; pp. 1142 - 1147
• Main Authors: Spychalla, James P., Kinney, Anthony J., Browse, John
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 18.02.1997; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences of the USA
• Subjects: Amino Acid Sequence; Animals; Arabidopsis; Arabidopsis - genetics; Biochemistry; Biological Sciences; Caenorhabditis elegans; Caenorhabditis elegans - enzymology; Caenorhabditis elegans - genetics; Cloning, Molecular; Complementary DNA; Enzymes; Fatty Acid Desaturases - genetics; Fatty acids; Fatty Acids - analysis; Flowers & plants; Gels; Genes; Genes, Helminth; Lipids; Molecular Sequence Data; Plants, Genetically Modified; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Soaps; Transgenic plants; Unsaturated fatty acids
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.4.1142

In animals, fatty acid desaturases catalyze key reactions in the synthesis of arachidonic acid and other polyunsaturated fatty acids. A search of the Caenorhabditis elegans DNA databases, using the sequences of Arabidopsis genes, identified several putative desaturases. Here we describe the characterization of the first of these genes, fat-1. The predicted protein encoded by a fat-1 cDNA showed 32-35% identity with both FAD2 and FAD3 of Arabidopsis. When expressed in transgenic plants, fat-1 resulted in a 90% increase in the proportion of α -linolenic acid in root lipids. Wild-type Arabidopsis incorporated ω -6 fatty acids (Δ 8,11,14-20:3 and Δ 5,8,11,14-20:4) into membrane lipids but did not desaturate them. By contrast, fat-1 transgenic plants efficiently desaturated both of these fatty acids to the corresponding ω -3 products. These findings indicate that the C. elegans fat-1 gene encodes the first animal representative of a class of glycerolipid desaturases that have previously been characterized in plants and cyanobacteria. The FAT-1 protein is an ω -3 fatty acyl desaturase that recognizes a range of 18- and 20-carbon ω -6 substrates.