Identification of allosteric binding sites of the allatostatin receptor type-C of pine processionary moth

Abstract

G-protein coupled receptors (GPCRs) are cell surface receptors that are consisted of seven-transmembrane α helices. Drugs targeting GPCRs account for one-third of clinically approved drugs; since many drugs target the conserved orthosteric site, they result in side effects like chronic administration, drug resistance, and desensitization. Allosteric sites are topographically distinct from the orthosteric site. Allosteric modu lators modulate the binding and signaling properties of the orthosteric site and orthos teric ligands, fine-tune receptor signaling, reduce the risk of overdosing, and increase specificity since they bind to structurally less conserved sites. Insect GPCRs are a potential target for developing pest control agents as many of these receptors regulate different physiological functions in insects. C-type Allatostatin Receptor (AstR-C) is a class A GPCR and regulates a vital pathway, Juvenile Hormone synthesis, presenting a potential pesticide target. Thaumetopoea pityocampa is the main factor that limits the development and survival of the Mediterranean pine forests. The study aims to provide a safer pesticide with efficient functionality by utilizing in silico and in vitro methods to identify allosteric binding pockets and find allosteric modulators of AstR-C. Various allosteric site prediction tools and blind-docking methods were employed to identify allosteric binding sites. Virtual screening was applied to three potential sites, and hit molecules were subjected to MD simulations and MM-GBSA analysis. Two potential allosteric sites were detected in transmembrane (TM) domains 4, 5, and ECL-2. A third pocket was determined between TM 3-4 and ICL-2. A total of 5 molecules, two molecules for each binding site, yielded promising results in the analyses.