Cloning of flax oleic fatty acid desaturase and its expression in yeast

Fatty acid desaturases dehydrogenate acyl chains, which results in the formation of a double bond. Using PCR on flax genomic DNA, we cloned a putative Delta 12 fatty acid desaturase (Fad2) gene encoding a 378 amino acid protein. Heterologous expression of this protein in yeast as an N-terminal fusion to GFP showed its localization within endoplasmic reticulum. Analysis of membrane lipids revealed the production of dienoic fatty acids, decreased levels of FAD2 substrates and an increased concentration of longer fatty acids. Higher peroxidation of lipids in FAD2-containing strains is not reflected by any visible phenotype in YPD medium. However, FAD2-containing strains with deleted superoxide dismutase genes exhibited significant growth reductions under oxidative stress.