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Maeda S, Xu J, N Kadji FM, Clark MJ, Zhao J, Tsutsumi N, Aoki J, Sunahara RK, Inoue A, Garcia KC, Kobilka BK. Structure and selectivity engineering of the M 1 muscarinic receptor toxin complex. Science 2020; 369:161-167. [PMID: 32646996 DOI: 10.1126/science.aax2517] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 04/21/2020] [Indexed: 12/13/2022]
Abstract
Muscarinic toxins (MTs) are natural toxins produced by mamba snakes that primarily bind to muscarinic acetylcholine receptors (MAChRs) and modulate their function. Despite their similar primary and tertiary structures, MTs show distinct binding selectivity toward different MAChRs. The molecular details of how MTs distinguish MAChRs are not well understood. Here, we present the crystal structure of M1AChR in complex with MT7, a subtype-selective anti-M1AChR snake venom toxin. The structure reveals the molecular basis of the extreme subtype specificity of MT7 for M1AChR and the mechanism by which it regulates receptor function. Through in vitro engineering of MT7 finger regions that was guided by the structure, we have converted the selectivity from M1AChR toward M2AChR, suggesting that the three-finger fold is a promising scaffold for developing G protein-coupled receptor modulators.
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Affiliation(s)
- Shoji Maeda
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Jun Xu
- Beijing Advanced Innovation Center for Structural Biology, School of Life Science, Tsinghua University, Beijing, China
| | | | - Mary J Clark
- Department of Pharmacology, University of California San Diego School of Medicine, La Jolla, CA 92093, USA
| | - Jiawei Zhao
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Naotaka Tsutsumi
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.,Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Junken Aoki
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai, Japan
| | - Roger K Sunahara
- Department of Pharmacology, University of California San Diego School of Medicine, La Jolla, CA 92093, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai, Japan
| | - K Christopher Garcia
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.,Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.,Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA. .,Beijing Advanced Innovation Center for Structural Biology, School of Life Science, Tsinghua University, Beijing, China
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Sabbir MG, Fernyhough P. Muscarinic receptor antagonists activate ERK-CREB signaling to augment neurite outgrowth of adult sensory neurons. Neuropharmacology 2018; 143:268-281. [PMID: 30248305 DOI: 10.1016/j.neuropharm.2018.09.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 08/09/2018] [Accepted: 09/12/2018] [Indexed: 01/09/2023]
Abstract
A major cellular effector activated by G protein coupled receptors is extracellular signal-regulated kinase (ERK). The ERK signaling cascade regulates a variety of cellular processes including growth and proliferation. Both G protein and β-arrestin-mediated signaling lead to ERK activation by phosphorylation through different kinases. Recently, we have shown muscarinic acetylcholine type 1 receptor (M1R) antagonists, muscarinic toxin 7 (MT7) and pirenzepine, elevated neurite outgrowth and protected from small and large fiber neuropathy in adult sensory neurons in various animal models. Thus, we tested the novel hypothesis that muscarinic antagonists could drive neurite outgrowth through altered M1R-ERK signaling. We have used two dimensional isoelectric focusing/SDS-PAGE combined with analysis using multiple phospho-epitope specific antibodies to study ERK1/2 phosphorylation and activation of its downstream nuclear effector cyclic response element binding protein (CREB). Activated CREB is known to exhibit neuroprotective and growth promoting effects. One hour of treatment with MT7 and pirenzepine activated ERK through M1R and induced a significant increase in levels of pCREB(S133) in cultured sensory neurons. Further, pharmacological blockade or siRNA based knockdown of ERK abolished the MT7 and pirenzepine mediated neuritogenic effect. In addition, we have shown drug-induced alterations of charged protein fractions that may possess additional post-translationally modified forms of ERK and CREB. For the first time we show that long-term treatment, e.g. 1 h, with muscarinic antagonists selective or specific for M1R can activate a biased β-arrestin dependent ERK-CREB signal cascade. Our study gives novel insight into muscarinic antagonist-mediated modulation of M1R-ERK-CREB signaling which could be exploited for therapy in neuropathic diseases.
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Affiliation(s)
- Mohammad Golam Sabbir
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, R2H 2A6, Canada.
| | - Paul Fernyhough
- Division of Neurodegenerative Disorders, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, R2H 2A6, Canada; Dept of Pharmacology & Therapeutics, University of Manitoba, MB, R3T 2N2, Canada.
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Xu J, Zhao H, Zheng Z, Wang Y, Niu Y, Wang H, Xu J, Lu Y, Chen H. Structural determinants for the interactions between muscarinic toxin 7 and muscarinic acetylcholine receptors. J Mol Recognit 2015; 28:239-52. [PMID: 25683330 DOI: 10.1002/jmr.2438] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 09/27/2014] [Accepted: 09/27/2014] [Indexed: 11/08/2022]
Abstract
Muscarinic acetylcholine receptors (mAChRs) have five subtypes and play crucial roles in various physiological functions and pathophysiological processes. Poor subtype specificity of mAChR modulators has been an obstacle to discover new therapeutic agents. Muscarinic toxin 7 (MT7) is a natural peptide toxin with high selectivity for the M1 receptor. With three to five residues substituted, M3, M4, and M5 receptor mutants could bind to MT7 at nanomolar concentration as the M1 receptor. However, the structural mechanisms explaining MT7-mAChRs binding are still largely unknown. In this study, we constructed 10 complex models of MT7 and each mAChR subtype or its mutant, performed molecular dynamics simulations, and calculated the binding energies to investigate the mechanisms. Our results suggested that the structural determinants for the interactions on mAChRs were composed of some critical residues located separately in the extracellular loops of mAChRs, such as Glu4.56, Leu4.60, Glu/Gln4.63, Tyr4.65, Glu/Asp6.67, and Trp7.35. The subtype specificity of MT7 was attributed to the non-conserved residues at positions 4.56 and 6.67. These structural mechanisms could facilitate the discovery of novel mAChR modulators with high subtype specificity and enhance the understanding of the interactions between ligands and G-protein-coupled receptors.
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Affiliation(s)
- Jianrong Xu
- Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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