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Dynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations
Ligand-gated ion channels are critical mediators of electrochemical signal transduction across evolution. Biophysical and pharmacological characterization of these receptor proteins relies on high-quality structures in multiple, subtly distinct functional states. However, structural data in this fam...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Life Science Alliance LLC
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8326787/ https://www.ncbi.nlm.nih.gov/pubmed/34210687 http://dx.doi.org/10.26508/lsa.202101011 |
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author | Rovšnik, Urška Zhuang, Yuxuan Forsberg, Björn O Carroni, Marta Yvonnesdotter, Linnea Howard, Rebecca J Lindahl, Erik |
author_facet | Rovšnik, Urška Zhuang, Yuxuan Forsberg, Björn O Carroni, Marta Yvonnesdotter, Linnea Howard, Rebecca J Lindahl, Erik |
author_sort | Rovšnik, Urška |
collection | PubMed |
description | Ligand-gated ion channels are critical mediators of electrochemical signal transduction across evolution. Biophysical and pharmacological characterization of these receptor proteins relies on high-quality structures in multiple, subtly distinct functional states. However, structural data in this family remain limited, particularly for resting and intermediate states on the activation pathway. Here, we report cryo-electron microscopy (cryo-EM) structures of the proton-activated Gloeobacter violaceus ligand-gated ion channel (GLIC) under three pH conditions. Decreased pH was associated with improved resolution and side chain rearrangements at the subunit/domain interface, particularly involving functionally important residues in the β1–β2 and M2–M3 loops. Molecular dynamics simulations substantiated flexibility in the closed-channel extracellular domains relative to the transmembrane ones and supported electrostatic remodeling around E35 and E243 in proton-induced gating. Exploration of secondary cryo-EM classes further indicated a low-pH population with an expanded pore. These results allow us to define distinct protonation and activation steps in pH-stimulated conformational cycling in GLIC, including interfacial rearrangements largely conserved in the pentameric channel family. |
format | Online Article Text |
id | pubmed-8326787 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Life Science Alliance LLC |
record_format | MEDLINE/PubMed |
spelling | pubmed-83267872021-08-11 Dynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations Rovšnik, Urška Zhuang, Yuxuan Forsberg, Björn O Carroni, Marta Yvonnesdotter, Linnea Howard, Rebecca J Lindahl, Erik Life Sci Alliance Research Articles Ligand-gated ion channels are critical mediators of electrochemical signal transduction across evolution. Biophysical and pharmacological characterization of these receptor proteins relies on high-quality structures in multiple, subtly distinct functional states. However, structural data in this family remain limited, particularly for resting and intermediate states on the activation pathway. Here, we report cryo-electron microscopy (cryo-EM) structures of the proton-activated Gloeobacter violaceus ligand-gated ion channel (GLIC) under three pH conditions. Decreased pH was associated with improved resolution and side chain rearrangements at the subunit/domain interface, particularly involving functionally important residues in the β1–β2 and M2–M3 loops. Molecular dynamics simulations substantiated flexibility in the closed-channel extracellular domains relative to the transmembrane ones and supported electrostatic remodeling around E35 and E243 in proton-induced gating. Exploration of secondary cryo-EM classes further indicated a low-pH population with an expanded pore. These results allow us to define distinct protonation and activation steps in pH-stimulated conformational cycling in GLIC, including interfacial rearrangements largely conserved in the pentameric channel family. Life Science Alliance LLC 2021-07-01 /pmc/articles/PMC8326787/ /pubmed/34210687 http://dx.doi.org/10.26508/lsa.202101011 Text en © 2021 Rovšnik et al. https://creativecommons.org/licenses/by/4.0/This article is available under a Creative Commons License (Attribution 4.0 International, as described at https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Research Articles Rovšnik, Urška Zhuang, Yuxuan Forsberg, Björn O Carroni, Marta Yvonnesdotter, Linnea Howard, Rebecca J Lindahl, Erik Dynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations |
title | Dynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations |
title_full | Dynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations |
title_fullStr | Dynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations |
title_full_unstemmed | Dynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations |
title_short | Dynamic closed states of a ligand-gated ion channel captured by cryo-EM and simulations |
title_sort | dynamic closed states of a ligand-gated ion channel captured by cryo-em and simulations |
topic | Research Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8326787/ https://www.ncbi.nlm.nih.gov/pubmed/34210687 http://dx.doi.org/10.26508/lsa.202101011 |
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