Evolution of multicomponent pheromone signals in small ermine moths involves a single fatty-acyl reductase gene

Abstract

Fatty-acyl CoA reductases (FAR) convert fatty acids into fatty alcohols in pro- and eukaryotic organisms. In the Lepidoptera, members of the FAR gene family serve in the biosynthesis of sex pheromones involved in mate communication. We used a group of closely related species, the small ermine moths (Lepidoptera: Yponomeutidae) as a model to investigate the role of FARs in the biosynthesis of complex pheromone blends. Homology-based molecular cloning in three Yponomeuta species led to the identification of multiple putative FAR transcripts homologous to FAR genes from the Bombyx mori genome. The expression of one transcript was restricted to the female pheromone-gland tissue, suggesting a role in pheromone biosynthesis, and the encoded protein belonged to a recently identified Lepidoptera-specific pgFAR gene subfamily. The Yponomeuta evonymellus pgFAR mRNA was up-regulated in sexually mature females and exhibited a 24-h cyclic fluctuation pattern peaking in the pheromone production period. Heterologous expression confirmed that the Yponomeuta pgFAR orthologs in all three species investigated [ Y. evonymellus (L.), Yponomeuta padellus (L.), and Yponomeuta rorellus (Hübner)] encode a functional FAR with a broad substrate range that efficiently promoted accumulation of primary alcohols in recombinant yeast supplied with a series of biologically relevant C14- or C16-acyl precursors. Taken together, our data evidence that a single alcohol-producing pgFAR played a critical function in the production of the multicomponent pheromones of yponomeutids and support the hypothesis of moth pheromone-biosynthetic FARs belonging to a FAR gene subfamily unique to Lepidoptera.

Biotechnological potential of insect fatty acid-modifying enzymes

“…+ binding domain and the C-terminal FAR_C domain is conserved among the FARs [89,96,98,100]. The common dehydrogenase/reductase active site motif YXXXK was experimentally confirmed to be indispensable for FAR enzymatic activity [167].…”

“…In silk moth (Bombyx mori), researchers discovered a pheromone gland-specific FAR [118] that is able to convert E10,Z12-16:2 FA precursor to the corresponding alcohol bombykol, the main component of the female sex pheromone. Since then, a range of moth pheromone-biosynthetic FARs have been isolated and functionally characterized [89,111,[119][120][121][122][123] (Table 2). Although moth FARs usually exhibit a broad substrate preference [77,89,111,120,122,123], some of them display specificity to unsaturated substrates with a double bond in either the E or Z configuration [119], a particular chain length and double bond position [120], or a system of conjugated double bonds [118].…”

“…Since then, a range of moth pheromone-biosynthetic FARs have been isolated and functionally characterized [89,111,[119][120][121][122][123] (Table 2). Although moth FARs usually exhibit a broad substrate preference [77,89,111,120,122,123], some of them display specificity to unsaturated substrates with a double bond in either the E or Z configuration [119], a particular chain length and double bond position [120], or a system of conjugated double bonds [118]. Given the multiple FAR paralogs generally present in insect genomes [13,14,16,17,111,124] and limited knowledge of their properties, there is a demand to perform functional characterization of these biologically and biotechnologically relevant enzymes.…”

Mechanisms of action and co-optive evolution for hypervariable courtship pheromones in plethodontid salamanders.

“…In the 50+ years since the discovery of bombykol, thousands of different chemicals have been identified in insects to perform similar functions, including frontalin in the invasive bark beetle (Dendroctonus valens) [12], heptacosadiene in fruit flies (Drosophila melanogaster) [13], derivatized fatty acids in ermine moths (Yponomeuta spp.) [14], and tetradecenyl acetates in European corn borer (Ostrinia nubialis) [15]. Presently, a major online phermone database, the Pherobase (http://www.pherobase.com), lists more than 6,500 different semiochemicals for over 7,000 species, the overwhelming majority of which are from insects.…”

“…While the experimental advantages of insects (small size, ease to maintain, short generation time, etc.) have allowed tremendous advances in the study of pheromones as a whole, their complex biosynthetic pathways have prohibited addressing many evolutionary questions with respect to modes and rates of selection [14].…”