Main content area

Gene characterized for membrane desaturase that produces (E)-11 isomers of mono- and diunsaturated fatty acids

Liu, W., Jiao, H., Murray, N.C., O'Connor, M., Roelofs, W.L.
Proceedings of the National Academy of Sciences of the United States of America 2002 v.99 no.2 pp. 620-624
Epiphyas postvittana, complementary DNA, amino acid sequences, monounsaturated fatty acids, genes, nucleotide sequences, pheromone glands, dienoic fatty acids, enzyme activity
Moth species have evolved integral membrane desaturases that exhibit a wide diversity in substrate specificity, as well as in regiospecificity and stereospecificity of the unsaturated products. We report here the cloning and expression of a single desaturase from the sex pheromone gland of the light brown apple moth, Epiphyas postvittana, that makes E11 isomers of monounsaturated (E11-16 and E11-14) fatty acids and a diunsaturated (E9,E11-14) fatty acid. In the pheromone gland, the monoene precursor is made available by beta oxidation of E11-16 acid with a subsequent two-carbon loss to E9-14 acid. A functional assay using a baculovirus expression system required addition of myristic acid and E9-14 acid precursors to demonstrate the unusual regiospecificity and stereospecificity of this desaturase. The amino acid sequence of this desaturase has approximately equal to 61% identity to that of Z11-desaturases from two other insect species, and only approximately equal to 48% identity to the metabolic Z9-desaturases in those species. A pheromone-gland Z9-desaturase gene also was found with the light brown apple moth that differed in its deduced amino acid sequence (66% identity) with the metabolic Z9-desaturase from fat body in this species.