Molecular mechanisms of bitopic ligand engagement with the M1 muscarinic acetylcholine receptor

Research output: Contribution to journalArticleResearchpeer-review

Abstract

TBPB and 77-LH-28-1 are selective agonists of the M1 muscarinic acetylcholine receptor (mAChR) that may gain their selectivity through a bitopic mechanism, interacting concomitantly with the orthosteric site and part of an allosteric site. The current study combined site-directed mutagenesis, analytical pharmacology,and molecular modeling to gain further insights into the structural basis underlying binding and signaling by these agonists. Mutations within the orthosteric binding site caused similar reductions in affinity and signaling efficacy for both selective and prototypical orthosteric ligands. In contrast, the mutation of residues within transmembrane helix (TM) 2 and the second extracellular loop (ECL2) discriminated between the different classes of ligand. In particular, ECL2 appears to be involved in the selective binding of bitopic ligands and in coordinating biased agonism between intracellular calcium mobilization and ERK1/2 phosphorylation. Molecular modeling of the interaction between TBPB and theM1 mAChR revealed a binding pose predicted to extend from the orthosteric site up toward a putative allosteric site bordered by TM2, TM3, and TM7, thus consistent with a bitopic mode of binding. Overall, these findings provide valuable structural and mechanistic insights into bitopic ligand actions and receptor activation and support a role for ECL2 in dictating the active states that can be adopted by aG protein-coupled receptor. This may enable greater selective ligand design and development for mAChRs and facilitate improved identification of bitopic ligands.
Original languageEnglish
Pages (from-to)23817 - 23837
Number of pages21
JournalJournal of Biological Chemistry
Volume289
Issue number34
DOIs
Publication statusPublished - 2014

Cite this

@article{7a133774ed5c42ecae70b4b80807fd37,
title = "Molecular mechanisms of bitopic ligand engagement with the M1 muscarinic acetylcholine receptor",
abstract = "TBPB and 77-LH-28-1 are selective agonists of the M1 muscarinic acetylcholine receptor (mAChR) that may gain their selectivity through a bitopic mechanism, interacting concomitantly with the orthosteric site and part of an allosteric site. The current study combined site-directed mutagenesis, analytical pharmacology,and molecular modeling to gain further insights into the structural basis underlying binding and signaling by these agonists. Mutations within the orthosteric binding site caused similar reductions in affinity and signaling efficacy for both selective and prototypical orthosteric ligands. In contrast, the mutation of residues within transmembrane helix (TM) 2 and the second extracellular loop (ECL2) discriminated between the different classes of ligand. In particular, ECL2 appears to be involved in the selective binding of bitopic ligands and in coordinating biased agonism between intracellular calcium mobilization and ERK1/2 phosphorylation. Molecular modeling of the interaction between TBPB and theM1 mAChR revealed a binding pose predicted to extend from the orthosteric site up toward a putative allosteric site bordered by TM2, TM3, and TM7, thus consistent with a bitopic mode of binding. Overall, these findings provide valuable structural and mechanistic insights into bitopic ligand actions and receptor activation and support a role for ECL2 in dictating the active states that can be adopted by aG protein-coupled receptor. This may enable greater selective ligand design and development for mAChRs and facilitate improved identification of bitopic ligands.",
author = "Peter Keov and Laura Lopez and Shane Devine and Celine Valant and Lane, {Jonathan Robert David} and Scammells, {Peter John} and Patrick Sexton and Arthur Christopoulos",
year = "2014",
doi = "10.1074/jbc.M114.582874",
language = "English",
volume = "289",
pages = "23817 -- 23837",
journal = "Journal of Biological Chemistry",
issn = "1083-351X",
publisher = "American Society for Biochemistry and Molecular Biology",
number = "34",

}

Molecular mechanisms of bitopic ligand engagement with the M1 muscarinic acetylcholine receptor. / Keov, Peter; Lopez, Laura; Devine, Shane; Valant, Celine; Lane, Jonathan Robert David; Scammells, Peter John; Sexton, Patrick; Christopoulos, Arthur.

In: Journal of Biological Chemistry, Vol. 289, No. 34, 2014, p. 23817 - 23837.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Molecular mechanisms of bitopic ligand engagement with the M1 muscarinic acetylcholine receptor

AU - Keov, Peter

AU - Lopez, Laura

AU - Devine, Shane

AU - Valant, Celine

AU - Lane, Jonathan Robert David

AU - Scammells, Peter John

AU - Sexton, Patrick

AU - Christopoulos, Arthur

PY - 2014

Y1 - 2014

N2 - TBPB and 77-LH-28-1 are selective agonists of the M1 muscarinic acetylcholine receptor (mAChR) that may gain their selectivity through a bitopic mechanism, interacting concomitantly with the orthosteric site and part of an allosteric site. The current study combined site-directed mutagenesis, analytical pharmacology,and molecular modeling to gain further insights into the structural basis underlying binding and signaling by these agonists. Mutations within the orthosteric binding site caused similar reductions in affinity and signaling efficacy for both selective and prototypical orthosteric ligands. In contrast, the mutation of residues within transmembrane helix (TM) 2 and the second extracellular loop (ECL2) discriminated between the different classes of ligand. In particular, ECL2 appears to be involved in the selective binding of bitopic ligands and in coordinating biased agonism between intracellular calcium mobilization and ERK1/2 phosphorylation. Molecular modeling of the interaction between TBPB and theM1 mAChR revealed a binding pose predicted to extend from the orthosteric site up toward a putative allosteric site bordered by TM2, TM3, and TM7, thus consistent with a bitopic mode of binding. Overall, these findings provide valuable structural and mechanistic insights into bitopic ligand actions and receptor activation and support a role for ECL2 in dictating the active states that can be adopted by aG protein-coupled receptor. This may enable greater selective ligand design and development for mAChRs and facilitate improved identification of bitopic ligands.

AB - TBPB and 77-LH-28-1 are selective agonists of the M1 muscarinic acetylcholine receptor (mAChR) that may gain their selectivity through a bitopic mechanism, interacting concomitantly with the orthosteric site and part of an allosteric site. The current study combined site-directed mutagenesis, analytical pharmacology,and molecular modeling to gain further insights into the structural basis underlying binding and signaling by these agonists. Mutations within the orthosteric binding site caused similar reductions in affinity and signaling efficacy for both selective and prototypical orthosteric ligands. In contrast, the mutation of residues within transmembrane helix (TM) 2 and the second extracellular loop (ECL2) discriminated between the different classes of ligand. In particular, ECL2 appears to be involved in the selective binding of bitopic ligands and in coordinating biased agonism between intracellular calcium mobilization and ERK1/2 phosphorylation. Molecular modeling of the interaction between TBPB and theM1 mAChR revealed a binding pose predicted to extend from the orthosteric site up toward a putative allosteric site bordered by TM2, TM3, and TM7, thus consistent with a bitopic mode of binding. Overall, these findings provide valuable structural and mechanistic insights into bitopic ligand actions and receptor activation and support a role for ECL2 in dictating the active states that can be adopted by aG protein-coupled receptor. This may enable greater selective ligand design and development for mAChRs and facilitate improved identification of bitopic ligands.

UR - http://www.jbc.org/content/289/34/23817.full.pdf+html

U2 - 10.1074/jbc.M114.582874

DO - 10.1074/jbc.M114.582874

M3 - Article

VL - 289

SP - 23817

EP - 23837

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 1083-351X

IS - 34

ER -