Identification and characterization of the bombykal receptor in the hawkmoth Manduca sexta

Abstract

Manduca sexta females attract their mates with the release of a species-specific sex-pheromone blend with bombykal (E,Z)-10,12-hexadcadienal and (E,E,Z)-10,12,14-hexadecatrienal being the two major components. Here, we searched for the hawkmoth bombykal receptor in heterologous expression systems. The putative pheromone receptor MsexOr1 co-expressed with MsexOrco in Xenopus oocytes elicited dose-dependent inward currents upon bombykal application (10 - 300 µM), and coexpressed in HEK293 and CHO cells caused bombykal-dependent rises in the intracellular free Ca2+ concentration. Also the bombykal receptor of Bombyx mori BmOr3 coexpressed with MsexOrco responded to bombykal (30 - 100 µM) with inward currents. In contrast, MsexOr4 coexpressed with MsexOrco neither responded to bombykal (30 - 100 µM) nor to the (E,E,Z)-10,12,14-hexadecatrienal mimic. Thus, MsexOr1, but probably not MsexOr4, and also not MsexOrco, is the bombykal-binding pheromone receptor in the hawkmoth. Finally, we obtained evidence that phospholipase C- and protein kinase C-activity is involved in the hawkmoth's bombykal-receptor-mediated Ca2+ signals in HEK293 and CHO cells.