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Tyrosine Residues That Control Binding and Gating in the 5-Hydroxytryptamine₃ Receptor Revealed by Unnatural Amino Acid Mutagenesis

Beene, Darren L. and Price, Kerry L. and Lester, Henry A. and Dougherty, Dennis A. and Lummis, Sarah C. R. (2004) Tyrosine Residues That Control Binding and Gating in the 5-Hydroxytryptamine₃ Receptor Revealed by Unnatural Amino Acid Mutagenesis. Journal of Neuroscience, 24 (41). pp. 9097-9104. ISSN 0270-6474. PMCID PMC6730062. https://resolver.caltech.edu/CaltechAUTHORS:20200427-084524229

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Abstract

The mechanism by which agonist binding triggers pore opening in ligand-gated ion channels is poorly understood. Here, we used unnatural amino acid mutagenesis to introduce subtle changes to the side chains of tyrosine residues (Tyr141, Tyr143, Tyr153, and Tyr234), which dominate the 5-HT₃ receptor binding site. Heterologous expression in oocytes, combined with radioligand binding data and a model of 5-HT (serotonin) computationally docked into the binding site, has allowed us to determine which of these residues are responsible for binding and/or gating. We have shown that Tyr 143 forms a hydrogen bond that is essential for receptor gating but does not affect binding, whereas a hydrogen bond formed by Tyr153 is involved in both binding and gating of the receptor. The aromatic group of Tyr234 is essential for binding and gating, whereas its hydroxyl does not affect binding but plays a steric role in receptor gating. Tyr141 is not involved in agonist binding or receptor gating but is important for antagonist interactions. These data, combined with a new model of the nonliganded 5-HT₃ receptor, lead to a mechanistic explanation of the interactions that initiate the conformational change leading to channel opening. Thus, we suggest that agonist entry into the binding pocket may displace Tyr143 and Tyr153 and results in their forming new hydrogen bonds. These bonds may form part of the network of bond rearrangements that trigger the conformational change leading to channel opening. Similar rearrangements may initiate gating in all Cys-loop receptors.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1523/jneurosci.2429-04.2004DOIArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6730062PubMed CentralArticle
ORCID:
AuthorORCID
Lester, Henry A.0000-0002-5470-5255
Dougherty, Dennis A.0000-0003-1464-2461
Lummis, Sarah C. R.0000-0001-9410-9805
Additional Information:© 2004 Society for Neuroscience. Received April 23, 2004; accepted July 20, 2004. This work was supported by The Wellcome Trust (S.C.R.L. is a Wellcome Trust Senior Research Fellow in Basic Biomedical Science), the Medical Research Council (a studentship to K.L.P.), and the National Institutes of Health (Grants NS11756 and NS34407). We thank Dr. Nigel Unwin for helpful discussions.
Funders:
Funding AgencyGrant Number
Wellcome TrustUNSPECIFIED
Medical Research Council (UK)UNSPECIFIED
NIHNS11756
NIHNS34407
Subject Keywords:ligand-gated ion channel; Cys-loop receptor; 5-HT3 receptor binding site; hydrogen bond; unnatural amino acids; activation mechanism; serotonin
Issue or Number:41
PubMed Central ID:PMC6730062
Record Number:CaltechAUTHORS:20200427-084524229
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200427-084524229
Official Citation:Tyrosine Residues That Control Binding and Gating in the 5-Hydroxytryptamine3 Receptor Revealed by Unnatural Amino Acid Mutagenesis. Darren L. Beene, Kerry L. Price, Henry A. Lester, Dennis A. Dougherty, Sarah C. R. Lummis. Journal of Neuroscience 13 October 2004, 24 (41) 9097-9104; DOI: 10.1523/JNEUROSCI.2429-04.2004
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102788
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:27 Apr 2020 15:52
Last Modified:27 Apr 2020 15:52

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