Characterization of expression of a plant oleate desaturase in yeast

We have expressed the oleate desaturase gene of Arabidopsis thaliana in Saccharomyces cerevisiae by means of a galactose-inducible promoter. Transfer of yeast cells to galactose-containing media and growth at 30 degrees C resulted in the production of active oleate desaturase, as shown by the appearance of the diunsaturated octadecadienoic acid (18:2) and hexadecadienoic acid (16:2). The highest level of these two fatty acids was 46.2%. In induced cultures, 18.2 appeared before 16:2, and we show that both of these fatty acids were present first on phosphatidylcholine and then appeared in other phospholipids and a neutral lipid fraction. We raised antibodies against the C-terminal 100 amino acids of oleate desaturase and demonstrated that this protein was in the microsomal fraction of induced cells.