Epimerisation of chiral hydroxylactones by short-chain dehydrogenases/reductases accounts for sex pheromone evolution in Nasonia

Abstract

Males of all species of the parasitic wasp genus Nasonia use (4R,5S)-5-hydroxy-4-decanolide (RS) as component of their sex pheromone while only N. vitripennis (Nv), employs additionally (4R,5R)-5-hydroxy-4-decanolide (RR). Three genes coding for the NAD+-dependent short-chain dehydrogenases/reductases (SDRs) NV10127, NV10128, and NV10129 are linked to the ability of Nv to produce RR. Here we show by assaying recombinant enzymes that SDRs from both Nv and N. giraulti (Ng), the latter a species with only RS in the pheromone, epimerise RS into RR and vice versa with (4R)-5-oxo-4-decanolide as an intermediate. Nv-derived SDR orthologues generally had higher epimerisation rates, which were also influenced by NAD+ availability. Semiquantitative protein analyses of the pheromone glands by tandem mass spectrometry revealed that NV10127 as well as NV10128 and/or NV10129 were more abundant in Nv compared to Ng. We conclude that the interplay of differential expression patterns and SDR epimerisation rates on the ancestral pheromone component RS accounts for the evolution of a novel pheromone phenotype in Nv.

Functional characterisation of two Δ12-desaturases demonstrates targeted production of linoleic acid as pheromone precursor inNasonia

“…The resulting 12,13-epoxy-octadec-9Z-enoic acid (3), is hydrolysed by the epoxide hydrolase NasviEH1 (Abdel-latief et al, 2008) to (12R,13S)-12,13-dihydroxy-octadec-9Zenoic acid (4); chain shortening by four steps of β-oxidation leads to (4R,5S)-4,5-dihydroxydecanoic acid (5) which lactonises to (4R,5S)-5-hydroxy-4-decanolide (6). Epimerisation of (6) by the short-chain dehydrogenases/ reductases (SDRs) NV10127, NV10128 and NV10129 with (4R)-5-oxodecanolide (7) occurring as an intermediate, finally leads to (4R,5R)-5-hydroxy-4-decanolide (8) (Niehuis et al, 2013;Ruther et al, 2016).…”

Chemical Ecology of the Parasitoid Wasp Genus Nasonia (Hymenoptera, Pteromalidae)

“…This is particularly interesting, as males of No appear to produce significantly smaller amounts of HDL indicating that No males do not rely on sex pheromone markings during mate acquisition (Diao et al, 2016). Furthermore, the genes encoding the epimerization of RS-to RR-HDL in Nv males are known (Niehuis et al, 2013;Ruther et al, 2016), and switching off RR-HDL production in Nv using RNA interference or the CRISPR/Cas 9 system (Li et al, 2017) combined with behavioral observations and fitness measurements in multiparasitized hosts might give valuable insights into the selection pressures that led to the evolution of RR-HDL in Nv.…”

“…The sequences of the Nasonia SDR genes are highly similar to those of enzymes catalyzing the deactivation of prostaglandins which serve various hormonal functions in insects (Stanley, 2006). This suggests that the SDRs epimerizing RS-to RR-HDL in Nv have evolved secondarily from these enzymes by gene duplication and neofunctionalization (Niehuis et al, 2013;Ruther et al, 2016). The three homologous SDRs differ significantly in their ability to epimerize RS-to RR-HDL.…”

“…Strikingly, genes encoding the SDRs that catalyze the epimerization of RS-to RR-HDL are also present in the genome of Ng and in vitro assays showed that the enzymes are also capable of catalyzing the epimerization albeit with a decreased efficiency. However, proteomic analyses of the pheromone glands showed a much higher expression in Nv suggesting that differential SDR gene expression underlies the pheromone difference between Nv and the other Nasonia species (Ruther et al, 2016). Why Nv is the only Nasonia species that evolved an additional pheromone component remains unclear so far, but likely involves the differences in the mating behavior, in particular the complete lack of WHM and thus strong dependency on the correct identification of conspecific male sex pheromone markings to find mates in this species.…”

“…Four steps of chain shortening by β-oxidation and lactonization of the resulting 4,5-dihydroxydecanoic acid then eventually leads to RS-HDL. RR-HDL is produced in Nv males by epimerization of RS-HDL using short-chain dehydrogenases/reductases (SDRs) encoded by the three genes NV10127, NV10128, and NV10129 positioned on chromosome 1 (Niehuis et al, 2013;Ruther et al, 2016). The sequences of the Nasonia SDR genes are highly similar to those of enzymes catalyzing the deactivation of prostaglandins which serve various hormonal functions in insects (Stanley, 2006).…”