Isolation and Characterization of a Δ5-Fatty Acid Desaturase fromCaenorhabditis elegans

Arachidonic acid and eicosapentaenoic acid are important precursors for the production of prostaglandins and other hormone-like eicosanoid molecules. These fatty acids are synthesized by animals by elongating and desaturating precursor fatty acids such as linoleic acid (18:2Δ9,12) and α-linolenic acid (18:3Δ9,12,15). We have identified a Δ5fatty acid desaturase gene (fat-4) from the nematodeCaenorhabditis elegans.We have expressed this gene product inSaccharomyces cerevisiaeand demonstrate that it readily converts di-homo-γ-linolenic acid (20:3Δ8,11,14) to arachidonic acid (20:4Δ5,8,11,14). The FAT-4 Δ5-desaturase also acts on a number of other substrates, including fatty acids that do not contain a double bond at the Δ8position.