A Novel Fatty Acyl Desaturase from the Pheromone Glands of Ctenopseustis obliquana and C. herana with Specific Z5-Desaturase Activity on Myristic Acid

Åsa K Hagström,Amali H Thirmawithana,Leah K Tooman,Christer Löfstedt,Jérôme Albre,Richard D Newcomb,Jacob Corcoran

doi:10.1007/s10886-013-0373-1

Åsa K Hagström, Amali H Thirmawithana + Show 5 more

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https://doi.org/10.1007/s10886-013-0373-1

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Abstract

Sexual communication in the Lepidoptera typically involves a female-produced sex pheromone that attracts males of the same species. The most common type of moth sex pheromone comprises individual or blends of fatty acyl derivatives that are synthesized by a specific enzymatic pathway in the female’s pheromone gland, often including a desaturation step. This reaction is catalyzed by fatty acyl desaturases that introduce double bonds at specific locations in the fatty acid precursor backbone. The two tortricid moths, Ctenopseustis obliquana and C. herana (brown-headed leafrollers), which are endemic in New Zealand, both use (Z)-5-tetradecenyl acetate as part of their sex pheromone. In C. herana, (Z)-5-tetradecenyl acetate is the sole component of the pheromone. Labeling experiments have revealed that this compound is produced via an unusual Δ5-desaturation of myristic acid. Previously six desaturases were identified from the pheromone glands of Ctenopseustis and its sibling genus Planotortrix, with one differentially regulated to produce the distinct blends used by individual species. However, none were able to conduct the Δ5-desaturation observed in C. herana, and presumably C. obliquana. We have now identified an additional desaturase gene, desat7, expressed in the pheromone glands of both Ctenopseustis species, which is not closely related to any previously described moth pheromone desaturase. The encoded enzyme displays Δ5-desaturase activity on myristic acid when heterologously expressed in yeast, but is not able to desaturate any other fatty acid (C8–C16). We conclude that desat7 represents a new group of desaturases that has evolved a role in the biosynthesis of sex pheromones in moths.Electronic supplementary materialThe online version of this article (doi:10.1007/s10886-013-0373-1) contains supplementary material, which is available to authorized users.

Highlights

The ability of potential mates to locate one another is essential in sexually-reproducing species
Moths utilize multi-component pheromone blends consisting of fatty acid derivatives, usually alcohols, aldehydes, or acetates (Blomquist et al 2005; Tillman et al 1999), which are synthesized in a specialized abdominal pheromone gland in female moths
A new gene predicted to encode a desaturase was identified from the transcriptomes of female pheromone glands from C. obliquana and C. herana using Blast searches with insect desaturases

Summary

Introduction

The ability of potential mates to locate one another is essential in sexually-reproducing species. Moths utilize multi-component pheromone blends consisting of fatty acid derivatives, usually alcohols, aldehydes, or acetates (Blomquist et al 2005; Tillman et al 1999), which are synthesized in a specialized abdominal pheromone gland in female moths. Fatty acids such as stearic and palmitic acid are processed by various enzymes, the first of which are generally fatty acyl desaturases that introduce one or more double bonds at specific locations in the carbon chain (Blomquist et al 2005; Jurenka 2004). The acids are reduced to alcohols by fatty acyl reductases (Moto et al 2004), the alcohols transformed to aldehydes by an alcohol oxidase (Teal and Tumlinson 1986), and acetates produced by acetyl transferase activity (Jurenka 2004)

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