An epoxide hydrolase involved in the biosynthesis of an insect sex attractant and its use to localize the production site

doi:10.1073/pnas.0801559105

An epoxide hydrolase involved in the biosynthesis of an insect sex attractant and its use to localize the production site

*Institut für Biologie, Freie Universität Berlin, Haderslebener Str. 9, D-12163 Berlin, Germany; and
^†Institut für Biotechnologie, Technische Universität Berlin, Seestraβe 13, D-13353 Berlin, Germany

Edited by Wendell Roelofs, Cornell University, Geneva, NY, and approved April 17, 2008 (received for review February 16, 2008)

Abstract

Epoxide hydrolases (EHs) are enzymes occurring in virtually any living organism. They catalyze the hydrolysis of epoxide containing lipids and are involved in crucial mechanisms, such as the detoxification of xenobiotics or the regulation of inflammation and blood pressure. Here, we describe a function of a putative EH gene in the biosynthesis of a sex attractant in the jewel wasp Nasonia vitripennis and use this gene to localize the site of pheromone production. Males of this parasitic wasp release a mixture of (4R,5R)-(threo-) and (4R,5S)-(erythro-)5-hydroxy-4-decanolide (HDL) to attract virgin females. Using a stable isotope labeled precursor, we demonstrated that vernolic acid ( erythro-12,13-epoxy-octadec-9Z-enoic acid) is converted by N. vitripennis males to threo-HDL. This suggested the involvement of an EH in hydrolyzing the fatty acid epoxide under inversion of the stereochemistry into the respective diol, which might be further processed by chain shortening and lactonization to HDL. We cloned a putative N. vitripennis EH gene (Nasvi-EH1) encoding 470 amino acids and localized its transcripts in the male rectal papillae by in situ RT-PCR. Chemical analyses and histological studies confirmed that males synthesize the sex attractant in the rectal vesicle and release it via the anal orifice. Involvement of Nasvi-EH1 in HDL biosynthesis was established by RNAi-mediated gene silencing. Injection of Nasvi-EH1 dsRNA into male abdomens inhibited pheromone biosynthesis by 55% and suppressed the targeted gene transcripts in the rectal vesicle by 95%.

Footnotes

^‡To whom correspondence should be addressed. E-mail: ruther{at}zedat.fu-berlin.de
Author contributions: M.A.-l. and J.R. designed research; M.A.-l., L.A.G., M.K., and J.R. performed research; L.A.G. contributed new reagents/analytic tools; M.A.-l. and J.R. analyzed data; and M.A.-l. and J.R. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
Data deposition: The sequence reported in this paper has been deposited in the GenBank database [accession no. EU441215 (Nasonia vitripennis Nasvi-EH1].
This article contains supporting information online at www.pnas.org/cgi/content/full/0801559105/DCSupplemental.