A multifunctional desaturase involved in the biosynthesis of the processionary moth sex pheromone

Abstract

The sex pheromone of the female processionary moth, Thaumetopoea pityocampa, is a unique C16 enyne acetate that is biosynthesized from palmitic acid. Three consecutive desaturation reactions transform this saturated precursor into the triunsaturated fatty acyl intermediate: formation of (Z)-11-hexadecenoic acid, acetylenation to 11-hexadecynoic acid, and final 13 desaturation to (Z)-13-hexadecen-11-ynoic acid. By using degenerate primers common to all reported insect desaturases, a single cDNA sequence was isolated from total RNA of T. pityocampa female pheromone glands. The full-length transcript of this putative desaturase was expressed in elo1 /ole1 yeast mutants (both elongase 1 and 9 desaturase-deficient) for functional assays. The construct fully rescued the ole1 yeast phenotype, confirming its desaturase activity. Analysis of the unsaturated products from transformed yeast extracts demonstrated that the cloned enzyme showed 11 desaturase, 11 acetylenase, and 13 desaturase activities. Therefore, this single desaturase may account for the three desaturation steps involved in the sex pheromone biosynthetic pathway of the processionary moth.