Probing the structural mechanism of partial agonism in glycine receptors using the fluorescent artificial amino acid, ANAP

Soh, Ming S., Estrada-Mondragon, Argel, Durisic, Nela, Keramidas, Angelo and Lynch, Joseph W. (2017) Probing the structural mechanism of partial agonism in glycine receptors using the fluorescent artificial amino acid, ANAP. ACS Chemical Biology, 12 3: 805-813. doi:10.1021/acschembio.6b00926


Author Soh, Ming S.
Estrada-Mondragon, Argel
Durisic, Nela
Keramidas, Angelo
Lynch, Joseph W.
Title Probing the structural mechanism of partial agonism in glycine receptors using the fluorescent artificial amino acid, ANAP
Journal name ACS Chemical Biology   Check publisher's open access policy
ISSN 1554-8937
1554-8929
Publication date 2017-03-17
Sub-type Article (original research)
DOI 10.1021/acschembio.6b00926
Open Access Status Not yet assessed
Volume 12
Issue 3
Start page 805
End page 813
Total pages 9
Place of publication Washington, DC, United States
Publisher American Chemical Society
Collection year 2018
Language eng
Formatted abstract
The efficacy of an agonist at a pentameric ligand-gated ion channel is determined by the rate at which it induces a conformational change from the resting closed state to a preopen ("flip") state. If the ability of an agonist to promote this isomerization is sufficiently low, then it becomes a partial agonist. As partial agonists at pentameric ligand-gated ion channels show considerable promise as therapeutics, understanding the structural basis of the resting-flip-state isomerization may provide insight into therapeutic design. Accordingly, we sought to identify structural correlates of the resting-flip conformational change in the glycine receptor chloride channel. We used nonsense suppression to introduce the small, fluorescent amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (ANAP), into specific sites in the extracellular and transmembrane domains. Then, under voltage-clamp conditions in Xenopus oocytes, we simultaneously quantified current and fluorescence responses induced by structurally similar agonists with high, medium, and low efficacies (glycine, β-alanine, and taurine, respectively). Analyzing results from nine ANAP-incorporated sites, we show that glycine receptor activation by agonists with graded efficacies manifests structurally as correspondingly graded movements of the β1-β2 loop, the β8-β9 loop, and the Cys-loop from the extracellular domain and the TM2-TM3 linker in the transmembrane domain. We infer that the resting-flip transition involves an efficacy-dependent molecular reorganization at the extracellular-transmembrane domain interface that primes receptors for efficacious opening.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
Queensland Brain Institute Publications
School of Biomedical Sciences Publications
 
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