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Chemical-Scale Studies on the Role of a Conserved Aspartate in Preorganizing the Agonist Binding Site of the Nicotinic Acetylcholine Receptor

Cashin, Amanda L. and Torrice, Michael M. and McMenimen, Kathryn A. and Lester, Henry A. and Dougherty, Dennis A. (2007) Chemical-Scale Studies on the Role of a Conserved Aspartate in Preorganizing the Agonist Binding Site of the Nicotinic Acetylcholine Receptor. Biochemistry, 46 (3). pp. 630-639. ISSN 0006-2960. PMCID PMC3164877. doi:10.1021/bi061638b. https://resolver.caltech.edu/CaltechAUTHORS:20170131-102250754

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Abstract

The nicotinic acetylcholine receptor and related Cys-loop receptors are ligand-gated ion channels that mediate fast synaptic transmission throughout the central and peripheral nervous system. A highly conserved aspartate residue (D89) that is near the agonist binding site but does not directly contact the ligand plays a critical part in receptor function. Here we probe the role of D89 using unnatural amino acid mutagenesis coupled with electrophysiology. Homology modeling implicates several hydrogen bonds involving D89. We find that no single hydrogen bond is essential to proper receptor function. Apparently, the side chain of D89 establishes a redundant network of hydrogen bonds; these bonds preorganize the agonist binding site by positioning a critical tryptophan residue that directly contacts the ligand. Earlier studies of the D89N mutant led to the proposal that a negative charge at this position is essential for receptor function. However, we find that receptors with neutral side chains at position 89 can function well, if the side chain is less perturbing than the amide of asparagine (nitro or keto groups allow function) or if a compensating backbone mutation is introduced to relieve unfavorable electrostatics.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/bi061638bDOIArticle
http://pubs.acs.org/doi/full/10.1021/bi061638bPublisherArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164877/PubMed CentralArticle
ORCID:
AuthorORCID
Lester, Henry A.0000-0002-5470-5255
Dougherty, Dennis A.0000-0003-1464-2461
Additional Information:© 2007 American Chemical Society. Received 11 August 2006. Published online 30 December 2006. Published in print 1 January 2007. This work was supported by the National Institutes of Health (Grants NS 34407 and NS 11756) and by the George Hoag Family Foundation. We thank Tingwei Mu for providing the unnatural amino acid Akp.
Funders:
Funding AgencyGrant Number
NIHNS 34407
NIHNS 11756
George Hoag Family FoundationUNSPECIFIED
Issue or Number:3
PubMed Central ID:PMC3164877
DOI:10.1021/bi061638b
Record Number:CaltechAUTHORS:20170131-102250754
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170131-102250754
Official Citation:Chemical-Scale Studies on the Role of a Conserved Aspartate in Preorganizing the Agonist Binding Site of the Nicotinic Acetylcholine Receptor Amanda L. Cashin, Michael M. Torrice, Kathryn A. McMenimen, Henry A. Lester, and Dennis A. Dougherty Biochemistry 2007 46 (3), 630-639 DOI: 10.1021/bi061638b
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73873
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:31 Jan 2017 19:56
Last Modified:11 Nov 2021 05:23

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