Isolation and Characterisation of a High-Efficiency Desaturase and Elongases from Microalgae for Transgenic LC-PUFA Production

The production of long-chain polyunsaturated fatty acids from precursor molecules linoleic acid (LA; 18:2 omega 6) and alpha-linolenic acid (ALA; 18:3 omega 3) is catalysed by sequential desaturase and elongase reactions. We report the isolation of a front-end Delta 6-desaturase gene from the microalgae Ostreococcus lucimarinus and two elongase genes, a Delta 6-elongase and a Delta 5-elongase, from the microalga Pyramimonas cordata. These enzymes efficiently convert their respective substrates when transformed in yeast (39-75% conversion for omega 3 substrate fatty acids), and the Delta 5-elongase in particular displays higher elongation efficiency (75% for conversion of eicosapentaenoic acid (20:5 omega 3) to docosapentaenoic acid (22:5 omega 3)) than previously reported genes. In addition, the Delta 6-desaturase is homologous with acyl-CoA desaturases and shows a strong preference for the omega 3 substrate ALA.