Functional and structural insights into a novel insect Gprotein-coupled receptor, allatostatin receptor type C ofpine processionary moth

Insect neuropeptides regulate different aspects of insect physiology. They exert their function via binding to their cognate receptor belonging to Class A G protein coupled receptors (GPCRs). Neuropeptide receptors are potential targets for nextgeneration pesticides. Allatostatin (AST) neuropeptides regulate the development of insects through the inhibition of juvenile hormone (JH) secretion. Here, Allatostatin receptor type C (AstR-C) of pine processionary moth, a pest in Mediterranean countries, was extracted from the whole genome sequencing (WGS) data. The receptor was cloned and characterized combining via different approaches. Using resonance energy transfer (RET)-based techniques, kinetics of G protein coupling and β -arrestin recruitment were investigated. Homology modeling, docking and molecular dynamics (MD) simulation approaches were conducted to predict the orthosteric pocket of the receptor which was validated by in silico and in vitro methods. The binding pocket was subjected to virtual screening studies to nd agonists. As a result, it was found that binding of the native ligand at sab-nanomolar and nanomolar ranges to the receptor induces Gi/o protein coupling and -arrestin recruitment, respectively. Kinetics studies revealed that a brief stimulation of the receptor at nanomolar range is enough to obtain a long-lasting response. The accuracy of the predicted orthosteric pocket was validated via G protein activation assay. Q2716:55 (Ballesteros-Weinstein numbering) was found to be critical for G protein-dependent activation of AstR-C. Virtual screening studies resulted in obtaining a small molecule capable of activating the receptor.