Mechanistic insights into allosteric structure-function relationships at the M1 muscarinic acetylcholine receptor

Alaa Abdul Ridha, Jonathan Robert David Lane, Shailesh Natvarbhai Mistry, Laura Lopez Munoz, Patrick Sexton, Peter John Scammells, Arthur Christopoulos, Meritxell Canals

Research output: Contribution to journalArticleResearchpeer-review

28 Citations (Scopus)

Abstract

Benzylquinolone carboxylic acid (BQCA) is the first highly selective positive allosteric modulator (PAM) for the M1 muscarinic acetylcholine receptor (mAChR), but it possesses low affinity for the allosteric site on the receptor. More recent drug discovery efforts identified 3-((1S,2S)-2-hydroxycyclohexyl)-6-((6-(1-methyl-1H-pyrazol-4-yl)pyridin-3-yl)methyl)benzo[h]-quinazolin-4(3H)-one (referred to herein as benzoquinazolinone 12) as a more potent M1 mAChR PAM with a structural ancestry originating from BQCA and related compounds. In the current study, we optimized the synthesis of and fully characterized the pharmacology of benzoquinazolinone 12, finding that its improved potency derived from a 50-fold increase in allosteric site affinity as compared with BQCA, while retaining a similar level of positive cooperativity with acetylcholine. We then utilized site-directed mutagenesis and molecular modeling to validate the allosteric binding pocket we previously described for BQCA as a shared site for benzoquinazolinone 12 and provide a molecular basis for its improved activity at the M1 mAChR. This includes a key role for hydrophobic and polar interactions with residues Tyr-179, in the second extracellular loop (ECL2) and Trp-4007.35 in transmembrane domain (TM) 7. Collectively, this study highlights how the properties of affinity and cooperativity can be differentially modified on a common structural scaffold and identifies molecular features that can be exploited to tailor the development of M1 mAChR-targeting PAMs.
Original languageEnglish
Pages (from-to)33701 - 33711
Number of pages11
JournalJournal of Biological Chemistry
Volume289
Issue number48
DOIs
Publication statusPublished - 2014

Cite this

Abdul Ridha, Alaa ; Lane, Jonathan Robert David ; Mistry, Shailesh Natvarbhai ; Lopez Munoz, Laura ; Sexton, Patrick ; Scammells, Peter John ; Christopoulos, Arthur ; Canals, Meritxell. / Mechanistic insights into allosteric structure-function relationships at the M1 muscarinic acetylcholine receptor. In: Journal of Biological Chemistry. 2014 ; Vol. 289, No. 48. pp. 33701 - 33711.
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abstract = "Benzylquinolone carboxylic acid (BQCA) is the first highly selective positive allosteric modulator (PAM) for the M1 muscarinic acetylcholine receptor (mAChR), but it possesses low affinity for the allosteric site on the receptor. More recent drug discovery efforts identified 3-((1S,2S)-2-hydroxycyclohexyl)-6-((6-(1-methyl-1H-pyrazol-4-yl)pyridin-3-yl)methyl)benzo[h]-quinazolin-4(3H)-one (referred to herein as benzoquinazolinone 12) as a more potent M1 mAChR PAM with a structural ancestry originating from BQCA and related compounds. In the current study, we optimized the synthesis of and fully characterized the pharmacology of benzoquinazolinone 12, finding that its improved potency derived from a 50-fold increase in allosteric site affinity as compared with BQCA, while retaining a similar level of positive cooperativity with acetylcholine. We then utilized site-directed mutagenesis and molecular modeling to validate the allosteric binding pocket we previously described for BQCA as a shared site for benzoquinazolinone 12 and provide a molecular basis for its improved activity at the M1 mAChR. This includes a key role for hydrophobic and polar interactions with residues Tyr-179, in the second extracellular loop (ECL2) and Trp-4007.35 in transmembrane domain (TM) 7. Collectively, this study highlights how the properties of affinity and cooperativity can be differentially modified on a common structural scaffold and identifies molecular features that can be exploited to tailor the development of M1 mAChR-targeting PAMs.",
author = "{Abdul Ridha}, Alaa and Lane, {Jonathan Robert David} and Mistry, {Shailesh Natvarbhai} and {Lopez Munoz}, Laura and Patrick Sexton and Scammells, {Peter John} and Arthur Christopoulos and Meritxell Canals",
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Mechanistic insights into allosteric structure-function relationships at the M1 muscarinic acetylcholine receptor. / Abdul Ridha, Alaa; Lane, Jonathan Robert David; Mistry, Shailesh Natvarbhai; Lopez Munoz, Laura; Sexton, Patrick; Scammells, Peter John; Christopoulos, Arthur; Canals, Meritxell.

In: Journal of Biological Chemistry, Vol. 289, No. 48, 2014, p. 33701 - 33711.

Research output: Contribution to journalArticleResearchpeer-review

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AU - Abdul Ridha, Alaa

AU - Lane, Jonathan Robert David

AU - Mistry, Shailesh Natvarbhai

AU - Lopez Munoz, Laura

AU - Sexton, Patrick

AU - Scammells, Peter John

AU - Christopoulos, Arthur

AU - Canals, Meritxell

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AB - Benzylquinolone carboxylic acid (BQCA) is the first highly selective positive allosteric modulator (PAM) for the M1 muscarinic acetylcholine receptor (mAChR), but it possesses low affinity for the allosteric site on the receptor. More recent drug discovery efforts identified 3-((1S,2S)-2-hydroxycyclohexyl)-6-((6-(1-methyl-1H-pyrazol-4-yl)pyridin-3-yl)methyl)benzo[h]-quinazolin-4(3H)-one (referred to herein as benzoquinazolinone 12) as a more potent M1 mAChR PAM with a structural ancestry originating from BQCA and related compounds. In the current study, we optimized the synthesis of and fully characterized the pharmacology of benzoquinazolinone 12, finding that its improved potency derived from a 50-fold increase in allosteric site affinity as compared with BQCA, while retaining a similar level of positive cooperativity with acetylcholine. We then utilized site-directed mutagenesis and molecular modeling to validate the allosteric binding pocket we previously described for BQCA as a shared site for benzoquinazolinone 12 and provide a molecular basis for its improved activity at the M1 mAChR. This includes a key role for hydrophobic and polar interactions with residues Tyr-179, in the second extracellular loop (ECL2) and Trp-4007.35 in transmembrane domain (TM) 7. Collectively, this study highlights how the properties of affinity and cooperativity can be differentially modified on a common structural scaffold and identifies molecular features that can be exploited to tailor the development of M1 mAChR-targeting PAMs.

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