Computational Study Predicts OR-Orco Heterotetramer as a Key Receptor for m-Cymene in Drosophila melanogaster (Diptera: Drosophilidae)

Abstract

Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) is a globally distributed pest that causes significant losses in fruit production, and novel approaches for management need to be explored. In this study, the host selection of D. melanogaster on four fruits was analyzed, revealing that Actinidia chinensis exhibited the strongest attractive effect. Subsequently, electrophysiological activities of volatiles from A. chinensis were identified by gas chromatography-electroantennographic detection (GC-EAD). The results demonstrated that methoxyphenyloxime, 1,1,2,3,3-pentamethylcyclobutane, and m-cymene induced significant electrophysiological responses in D. melanogaster. Among these volatiles, m-cymene was shown to be attractive to this pest at concentrations of 0.2%–0.7%. However, at a concentration of 1.0%, it exhibited a significant repellent effect. Based on data from the DoOR 2.0, Or19a and Or71a were selected for computational prediction to elucidate the molecular mechanisms underlying m-cymene recognition, and Orco was included in the analysis by AlphaFold 3, Protein X, and Chai-1. The results suggested that both Or19a and Or71a form heterotetrameric complexes with Orco at a 1:3 stoichiometric ratio and that these complexes display robust binding affinities for m-cymene. The binding energy of the Or71a-Orco-ligand and Or19a-Orco-ligand complexes was (−24.50 ± 1.00) kcal/mol and (−23.13 ± 0.38) kcal/mol, respectively. Further characterization of the OR-Orco binding interfaces revealed that the positively charged regions of the two ORs were closely associated with the negatively charged regions of Orco and vice versa. This study aims to establish theoretical foundations for improved monitoring and control strategies of D. melanogaster and to provide mechanistic insights into host recognition at the molecular level.