CHARACTERIZATION OF EXPRESSION OF A PLANT OLEATE DESATURASE IN YEAST

We have expressed the oleate desaturase gene of Arabidopsis thaliana i n Saccharomyces cerevisiae by means of a galactose-inducible promoter. Transfer of yeast cells to galactose-containing media and growth at 3 0 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 fa tty acids was 46.2%. In induced cultures, 18.2 appeared before 16:2, a nd we show that both of these fatty acids were present first on phosph atidylcholine and then appeared in other phospholipids and a neutral l ipid fraction. We raised antibodies against the C-terminal 100 amino a cids of oleate desaturase and demonstrated that this protein was in th e microsomal fraction of induced cells.