The role of desaturases in the biosynthesis of marking pheromones in bumblebee males

• Published in: Insect biochemistry and molecular biology 2013-08, Vol.43 (8), p.724-731
• Main Authors: Buček, Aleš, Vogel, Heiko, Matoušková, Petra, Prchalová, Darina, Žáček, Petr, Vrkoslav, Vladimír, Šebesta, Petr, Svatoš, Aleš, Jahn, Ullrich, Valterová, Irena, Pichová, Iva
• Format: Article
• Language: English
• Subjects: acyltransferases; Animals; Bees - enzymology; Bees - genetics; biosynthesis; Bombus lapidarius; Bombus lucorum; Bombus terrestris; Bumblebee; fat body; Fatty acid desaturase; Fatty Acid Desaturases - isolation & purification; Fatty Acid Desaturases - metabolism; fatty acids; Functional expression; gene expression regulation; Hymenoptera; Insect Proteins - isolation & purification; Insect Proteins - metabolism; Male; males; Pheromone; pheromones; Pheromones - biosynthesis; Phylogeny; RNA; RNA-seq; Sequence Analysis, DNA; Stearoyl-CoA Desaturase - metabolism; terpenoids; transcriptomics; triacylglycerol lipase; yeasts
• ISSN: 0965-1748; 1879-0240
• DOI: 10.1016/j.ibmb.2013.05.003

Bumblebee males (Hymenoptera) produce species-specific labial gland secretions called marking pheromones (MPs). MPs generally consist of terpenoids and fatty-acid-derived aliphatic compounds with various chain lengths predominantly containing one or no double bonds. The unsaturated fatty-acid-derived MP components were hypothesized to be produced by fatty acid desaturases (FADs) that exhibit diverse substrate specificities. To address this hypothesis, we isolated and functionally characterized FADs from three bumblebee species: Bombus lucorum, Bombus terrestris, and Bombus lapidarius. By employing RNA sequencing of the male labial glands and fat bodies of B. lucorum and B. terrestris, we identified five paralogous FAD-like sequences but only two FAD lineages were abundant and differentially expressed in the labial glands. We found that abundant FAD lineages were also expressed in the labial gland and fat body of Bombus lapidarius. Functional characterization of FADs in a yeast expression system confirmed that Δ4-FADs exhibited a unique Δ4-desaturase activity exclusively on 14-carbon fatty acyls and Δ9-FADs displayed Δ9-desaturase activity on 14- to 18-carbon fatty acyls. These results indicate that Δ9-FADs are involved in the biosynthesis of major unsaturated components of MPs in B. lucorum and B. lapidarius despite the diverse MP composition of these bumblebee species. The contribution of lipases, acyltransferases, esterases, and fatty acid reductases to production of the species-specific MP composition is also discussed in light of the transcriptomic data obtained in this study. [Display omitted] •The transcriptomes of pheromone glands from two bumblebee species were obtained.•Selected desaturase paralogs from three species were functionally characterized.•FAD specificities are conserved despite the diverse pheromone blend composition.•Δ4-FADs are unique Δ4-desaturases with an elusive biological role.•Δ9-FADs are involved in the biosynthesis of unsaturated male bumblebee pheromones.