Activation of a Muscarinic G-Protein Coupled Receptor and Structure-Based Design of Allosteric Modulators

Abstract

G-protein coupled receptors (GPCRs) are important cell signaling membrane proteins that represent primary targets of about one third of currently marketed drugs. The M2 muscarinic receptor is a key GPCR that regulates the human heart rate and contractile forces of cardiomyocytes, and is thus targeted for treating many heart diseases. Here, we have performed long-timescale accelerated molecular dynamics (aMD) simulations and captured activation of the M2 receptor at an atomistic level [1]. The receptor activation is characterized by large-scale structural rearrangements of the transmembrane helices and conformational changes in the inter-helical salt bridge and hydrogen bond interactions [2]. Furthermore, using the aMD simulation-derived structural ensembles that account for the receptor flexibility, we have mapped the receptor surface for druggable allosteric sites [3] and targeted the extracellular vestibule for designing allosteric modulators. Retrospective docking of known ligands is first carried out to validate the simulation receptor ensembles, followed by prospective docking to predict new allosteric ligands from the National Cancer Institute compound library. The computationally selected lead compounds are finally tested using experimental binding and functional assays to identify potential allosteric modulators of the M2 muscarinic GPCR [4].1. Miao, Y., et al., Activation and dynamic network of the M2 muscarinic receptor. Proc Natl Acad Sci U S A, 2013. 110(27): p. 10982-10987.2. Miao, Y., S.E. Nichols, and J.A. McCammon, Free Energy Landscape of G-Protein Coupled Receptors, Explored by Accelerated Molecular Dynamics. Physical Chemistry Chemical Physics, 2014. 16(14): p. 6398-6406.3. Miao, Y., S.E. Nichols, and J.A. McCammon, Mapping of Allosteric Druggable Sites in Activation-Associated Conformers of the M2 Muscarinic Receptor. Chemical Biology & Drug Design, 2013. 83(2): p. 237-246.4. Miao, Y., et al., Structural-Based Design of Allosteric Modulators of the M2 Muscarinic G-protein Coupled Receptor. In Preparation, 2015.