CYPs in different families are involved in the divergent regio-specific epoxidation of alkenyl sex pheromone precursors in moths

Abstract

In moth species that utilize alkenyl sex pheromones, the epoxidation of alkenes confers further diversity on the chemical structures of pheromone components. Hc_epo1 (CYP341B14), the first pheromone gland (PG)-specific epoxidase identified from the fall webworm Hyphantria cunea (Erebidae), specifically epoxidizes the Z9 double bond in the triene precursor, (3Z,6Z,9Z)-3,6,9-henicosatriene (Z3,Z6,Z9-21:H). In the present study, we identified a novel PG-specific epoxidase, As_epo1, from the Japanese giant looper Ascotis selenaria (Geometridae), which secretes cis-3,4-epoxy-(6Z,9Z)-6,9-nonadecadiene (epo3,Z6,Z9-19:H) as the main sex pheromone component. A functional assay using the Sf9 insect cell line-baculovirus expression system showed that As_epo1 specifically epoxidizes the Z3 double bond in the pheromone precursor triene, (3Z,6Z,9Z)-3,6,9-nonadecatriene (Z3,Z6,Z9-19:H). As_epo1 also Z3-specifically epoxidized a triene with a longer carbon chain, Z3,Z6,Z9-21:H, which does not occur in this species. A phylogenetic analysis indicated that As_epo1 belonged to the CYP340 family, not the CYP341 family to which Hc_epo1 belongs. These results suggest that moth PG-specific epoxidases with divergent regio-specificities have evolved independently.

Keywords: Ascotis selenaria; CYP; Cytochrome P450; Epoxidase; Sex pheromone biosynthesis.