Two single-point mutations shift the ligand selectivity of a pheromone receptor between two closely related moth species.

Ke Yang,Chao Ning,Chen-Zhu Wang,Ling-Qiao Huang

doi:10.7554/elife.29100

Abstract

Male moths possess highly sensitive and selective olfactory systems that detect sex pheromones produced by their females. Pheromone receptors (PRs) play a key role in this process. The PR HassOr14b is found to be tuned to (Z)-9-hexadecenal, the major sex-pheromone component, in Helicoverpa assulta. HassOr14b is co-localized with HassOr6 or HassOr16 in two olfactory sensory neurons within the same sensilla. As HarmOr14b, the ortholog of HassOr14b in the closely related species Helicoverpa armigera, is tuned to another chemical (Z)-9-tetradecenal, we study the amino acid residues that determine their ligand selectivity. Two amino acids located in the transmembrane domains F232I and T355I together determine the functional difference between the two orthologs. We conclude that species-specific changes in the tuning specificity of the PRs in the two Helicoverpa moth species could be achieved with just a few amino acid substitutions, which provides new insights into the evolution of closely related moth species.

Highlights

Almost all animals detect and react to pheromones and the other chemical cues that indicate food, shelter or predators, and their olfactory systems are mainly involved in the processes (Wyatt, 2003)
We identify HassOr14b as the Pheromone receptors (PRs) tuned to Z9-16:Ald, the major sex-pheromone component of H. assulta
Its ortholog HarmOr14b is specific for Z9-14:Ald in H. armigera and we further demonstrate that two single-point mutations, F232I and T355I, located in the intracellular domains of the receptor, together determine the functional shift between orthologs in the two closely related species

Summary

Introduction

Almost all animals detect and react to pheromones and the other chemical cues that indicate food, shelter or predators, and their olfactory systems are mainly involved in the processes (Wyatt, 2003). Pheromones are enormously varied in different animal species. Moths are good model systems for pheromone communication study. Male moths fly upwind to find conspecific females releasing a plume of sex pheromone (Cardeand Haynes, 2004). Most moth sex pheromones have multiple components present in specific ratios that play significant roles in intraspecific sexual communication and in interspecific reproductive isolation (Cardeet al., 1977). Male moths possess highly sensitive and selective olfactory sensory neurons (OSNs) located in antennal sensilla that detect the pheromone molecules (Schneider, 1964; Hansson and Stensmyr, 2011). Pheromone receptors (PRs) located in the dendritic membrane of OSNs play a pivotal role in peripheral coding of sex pheromones (Leal, 2013; Sakurai et al, 2004)

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