Identification of a novel allosteric site at the M5 muscarinic acetylcholine receptor

Burger, W. A. C. et al. (2021) Identification of a novel allosteric site at the M5 muscarinic acetylcholine receptor. ACS Chemical Neuroscience, 12(16), pp. 3112-3123. (doi: 10.1021/acschemneuro.1c00383) (PMID:34351123)

Abstract

The M5 muscarinic acetylcholine receptor (mAChR) has emerged as an exciting therapeutic target for the treatment of addiction and behavioral disorders. This has been in part due to promising preclinical studies with the M5 mAChR selective negative allosteric modulator (NAM), ML375. The binding site of ML375 remains unknown, however, making it difficult to develop improved M5 mAChR selective modulators. To determine the possible location of the ML375 binding site, we used radioligand binding and functional assays to show that ML375 does not interact with the well-characterized “common” mAChR allosteric site located in the receptor’s extracellular vestibule, nor a previously proposed second allosteric site recognized by the modulator, amiodarone. Molecular docking was used to predict potential allosteric sites within the transmembrane (TM) domain of the M5 mAChR. These predicted sites were assessed using M5–M2 mAChR receptor chimeras and further targeted with site-directed mutagenesis, which enabled the identification of a putative binding site for ML375 at the interface of TMs 2–4. Collectively, these results identify a third allosteric site at the M5 mAChR and highlight the ability of allosteric modulators to selectively target highly conserved proteins.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Tobin, Andrew
• Authors: Burger, W. A. C., Gentry, P. R., Berizzi, A. E., Vuckovic, Z., van der Westhuizen, E. T., Thompson, G., Yeasmin, M., Lindsley, C. W., Sexton, P. M., Langmead, C. J., Tobin, A. B., Christopoulos, A., Valant, C., and Thal, D. M.
• College/School: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
• Journal Name: ACS Chemical Neuroscience
• Publisher: American Chemical Society
• ISSN: 1948-7193
• ISSN (Online): 1948-7193
• Published Online: 05 August 2021

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
173304		Collaborative Network to Define the Molecular Determinants of G Protein Coupled Receptor Clinical Efficacy	Andrew Tobin	Wellcome Trust (WELLCOTR)	201529/Z/16/Z	MCSB - Molecular Pharmacology