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Identification of an animal omega-3 fatty acid desaturase by heterologous expression in Arabidopsis
- Spychalla, J.P., Kinney, A.J., Browse, J.
- Proceedings of the National Academy of Sciences of the United States of America 1997 v.94 no.4 pp. 1142-1147
- Arabidopsis thaliana, transgenic plants, gene expression, stearoyl-CoA desaturase, complementary DNA, Caenorhabditis elegans, nucleotide sequences, amino acid sequences, linolenic acid, fatty acids, lipids, cell membranes, roots, polyunsaturated fatty acids, chemical constituents of plants
- 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 alpha-linolenic acid in root lipids. Wild-type Arabidopsis incorporated omega-6 fatty acids (delta8,11,14-20:3 and delta5,8,11,14-20:4) into membrane lipids but did not desaturate them. By contrast,fat-1 transgenic plants efficiently desaturated both of these fatty acids to the corresponding omega-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 omega-3 fatty acyl desaturase that recognizes a range of 18- and 20-carbon omega-6 substrates.