Structural basis for odorant recognition of the insect odorant receptor OR-Orco heterocomplex.

Abstract

Insects detect and discriminate a diverse array of chemicals using odorant receptors (ORs), which are ligand-gated ion channels comprising a divergent odorant-sensing OR and a conserved odorant receptor co-receptor (Orco). In this work, we report structures of the <i>Ap</i>OR5-Orco heterocomplex from the pea aphid <i>Acyrthosiphon pisum</i> alone and bound to its known activating ligand, geranyl acetate. In these structures, three <i>Ap</i>Orco subunits serve as scaffold components that cannot bind the ligand and remain relatively unchanged. Upon ligand binding, the pore-forming helix S7b of <i>Ap</i>OR5 shifts outward from the central pore axis, causing an asymmetrical pore opening for ion influx. Our study provides insights into odorant recognition and channel gating of the OR-Orco heterocomplex and offers structural resources to support development of innovative insecticides and repellents for pest control.