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Structure-guided unlocking of Na(X) reveals a non-selective tetrodotoxin-sensitive cation channel

Unlike classical voltage-gated sodium (Na(V)) channels, Na(X) has been characterized as a voltage-insensitive, tetrodotoxin-resistant, sodium (Na(+))-activated channel involved in regulating Na(+) homeostasis. However, Na(X) remains refractory to functional characterization in traditional heterologo...

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Autores principales: Noland, Cameron L., Chua, Han Chow, Kschonsak, Marc, Heusser, Stephanie Andrea, Braun, Nina, Chang, Timothy, Tam, Christine, Tang, Jia, Arthur, Christopher P., Ciferri, Claudio, Pless, Stephan Alexander, Payandeh, Jian
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8931054/
https://www.ncbi.nlm.nih.gov/pubmed/35301303
http://dx.doi.org/10.1038/s41467-022-28984-4
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author Noland, Cameron L.
Chua, Han Chow
Kschonsak, Marc
Heusser, Stephanie Andrea
Braun, Nina
Chang, Timothy
Tam, Christine
Tang, Jia
Arthur, Christopher P.
Ciferri, Claudio
Pless, Stephan Alexander
Payandeh, Jian
author_facet Noland, Cameron L.
Chua, Han Chow
Kschonsak, Marc
Heusser, Stephanie Andrea
Braun, Nina
Chang, Timothy
Tam, Christine
Tang, Jia
Arthur, Christopher P.
Ciferri, Claudio
Pless, Stephan Alexander
Payandeh, Jian
author_sort Noland, Cameron L.
collection PubMed
description Unlike classical voltage-gated sodium (Na(V)) channels, Na(X) has been characterized as a voltage-insensitive, tetrodotoxin-resistant, sodium (Na(+))-activated channel involved in regulating Na(+) homeostasis. However, Na(X) remains refractory to functional characterization in traditional heterologous systems. Here, to gain insight into its atypical physiology, we determine structures of the human Na(X) channel in complex with the auxiliary β3-subunit. Na(X) reveals structural alterations within the selectivity filter, voltage sensor-like domains, and pore module. We do not identify an extracellular Na(+)-sensor or any evidence for a Na(+)-based activation mechanism in Na(X). Instead, the S6-gate remains closed, membrane lipids fill the central cavity, and the domain III-IV linker restricts S6-dilation. We use protein engineering to identify three pore-wetting mutations targeting the hydrophobic S6-gate that unlock a robust voltage-insensitive leak conductance. This constitutively active Na(X)-QTT channel construct is non-selective among monovalent cations, inhibited by extracellular calcium, and sensitive to classical Na(V) channel blockers, including tetrodotoxin. Our findings highlight a functional diversity across the Na(V) channel scaffold, reshape our understanding of Na(X) physiology, and provide a template to demystify recalcitrant ion channels.
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spelling pubmed-89310542022-04-01 Structure-guided unlocking of Na(X) reveals a non-selective tetrodotoxin-sensitive cation channel Noland, Cameron L. Chua, Han Chow Kschonsak, Marc Heusser, Stephanie Andrea Braun, Nina Chang, Timothy Tam, Christine Tang, Jia Arthur, Christopher P. Ciferri, Claudio Pless, Stephan Alexander Payandeh, Jian Nat Commun Article Unlike classical voltage-gated sodium (Na(V)) channels, Na(X) has been characterized as a voltage-insensitive, tetrodotoxin-resistant, sodium (Na(+))-activated channel involved in regulating Na(+) homeostasis. However, Na(X) remains refractory to functional characterization in traditional heterologous systems. Here, to gain insight into its atypical physiology, we determine structures of the human Na(X) channel in complex with the auxiliary β3-subunit. Na(X) reveals structural alterations within the selectivity filter, voltage sensor-like domains, and pore module. We do not identify an extracellular Na(+)-sensor or any evidence for a Na(+)-based activation mechanism in Na(X). Instead, the S6-gate remains closed, membrane lipids fill the central cavity, and the domain III-IV linker restricts S6-dilation. We use protein engineering to identify three pore-wetting mutations targeting the hydrophobic S6-gate that unlock a robust voltage-insensitive leak conductance. This constitutively active Na(X)-QTT channel construct is non-selective among monovalent cations, inhibited by extracellular calcium, and sensitive to classical Na(V) channel blockers, including tetrodotoxin. Our findings highlight a functional diversity across the Na(V) channel scaffold, reshape our understanding of Na(X) physiology, and provide a template to demystify recalcitrant ion channels. Nature Publishing Group UK 2022-03-17 /pmc/articles/PMC8931054/ /pubmed/35301303 http://dx.doi.org/10.1038/s41467-022-28984-4 Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Noland, Cameron L.
Chua, Han Chow
Kschonsak, Marc
Heusser, Stephanie Andrea
Braun, Nina
Chang, Timothy
Tam, Christine
Tang, Jia
Arthur, Christopher P.
Ciferri, Claudio
Pless, Stephan Alexander
Payandeh, Jian
Structure-guided unlocking of Na(X) reveals a non-selective tetrodotoxin-sensitive cation channel
title Structure-guided unlocking of Na(X) reveals a non-selective tetrodotoxin-sensitive cation channel
title_full Structure-guided unlocking of Na(X) reveals a non-selective tetrodotoxin-sensitive cation channel
title_fullStr Structure-guided unlocking of Na(X) reveals a non-selective tetrodotoxin-sensitive cation channel
title_full_unstemmed Structure-guided unlocking of Na(X) reveals a non-selective tetrodotoxin-sensitive cation channel
title_short Structure-guided unlocking of Na(X) reveals a non-selective tetrodotoxin-sensitive cation channel
title_sort structure-guided unlocking of na(x) reveals a non-selective tetrodotoxin-sensitive cation channel
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8931054/
https://www.ncbi.nlm.nih.gov/pubmed/35301303
http://dx.doi.org/10.1038/s41467-022-28984-4
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