Identification of a Caenorhabditis elegans Δ6-fatty-acid-desaturase by heterologous expression in Saccharomyces cerevisiae Available to Purchase

We identified a cDNA expressed sequence tag from an animal (the nematode worm Caenorhabditis elegans) that showed weak similarity to a higher-plant microsomal Δ⁶-desaturase. A full-length cDNA clone was isolated and expressed in the yeast Saccharomyces cerevisiae. This demonstrated that the protein encoded by the C. elegans cDNA was that of a fatty acid Δ⁶-desaturase, as determined by the accumulation of γ-linolenic acid. The C. elegans Δ⁶-desaturase contained an N-terminalcytochrome b₅ domain, indicating that it had a similar structure to that of the higher-plant Δ⁶-desaturase. The C. elegans Δ⁶-desaturase mapped to cosmid W08D2, a region of chromosome III. This is the first example of a Δ⁶-desaturase isolated from an animal and also the first example of an animal desaturase containing a cytochrome b₅ domain.