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Molecular determinants of pH sensing in the proton-activated chloride channel

In response to acidic pH, the widely expressed proton-activated chloride (PAC) channel opens and conducts anions across cellular membranes. By doing so, PAC plays an important role in both cellular physiology (endosome acidification) and diseases associated with tissue acidosis (acid-induced cell de...

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Autores principales: Osei-Owusu, James, Kots, Ekaterina, Ruan, Zheng, Mihaljević, Ljubica, Chen, Kevin Hong, Tamhaney, Ami, Ye, Xinyu, Lü, Wei, Weinstein, Harel, Qiu, Zhaozhu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9351481/
https://www.ncbi.nlm.nih.gov/pubmed/35878032
http://dx.doi.org/10.1073/pnas.2200727119
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author Osei-Owusu, James
Kots, Ekaterina
Ruan, Zheng
Mihaljević, Ljubica
Chen, Kevin Hong
Tamhaney, Ami
Ye, Xinyu
Lü, Wei
Weinstein, Harel
Qiu, Zhaozhu
author_facet Osei-Owusu, James
Kots, Ekaterina
Ruan, Zheng
Mihaljević, Ljubica
Chen, Kevin Hong
Tamhaney, Ami
Ye, Xinyu
Lü, Wei
Weinstein, Harel
Qiu, Zhaozhu
author_sort Osei-Owusu, James
collection PubMed
description In response to acidic pH, the widely expressed proton-activated chloride (PAC) channel opens and conducts anions across cellular membranes. By doing so, PAC plays an important role in both cellular physiology (endosome acidification) and diseases associated with tissue acidosis (acid-induced cell death). Despite the available structural information, how proton binding in the extracellular domain (ECD) leads to PAC channel opening remains largely unknown. Here, through comprehensive mutagenesis and electrophysiological studies, we identified several critical titratable residues, including two histidine residues (H130 and H131) and an aspartic acid residue (D269) at the distal end of the ECD, together with the previously characterized H98 at the transmembrane domain–ECD interface, as potential pH sensors for human PAC. Mutations of these residues resulted in significant changes in pH sensitivity. Some combined mutants also exhibited large basal PAC channel activities at neutral pH. By combining molecular dynamics simulations with structural and functional analysis, we further found that the β12 strand at the intersubunit interface and the associated “joint region” connecting the upper and lower ECDs allosterically regulate the proton-dependent PAC activation. Our studies suggest a distinct pH-sensing and gating mechanism of this new family of ion channels sensitive to acidic environment.
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spelling pubmed-93514812023-01-25 Molecular determinants of pH sensing in the proton-activated chloride channel Osei-Owusu, James Kots, Ekaterina Ruan, Zheng Mihaljević, Ljubica Chen, Kevin Hong Tamhaney, Ami Ye, Xinyu Lü, Wei Weinstein, Harel Qiu, Zhaozhu Proc Natl Acad Sci U S A Biological Sciences In response to acidic pH, the widely expressed proton-activated chloride (PAC) channel opens and conducts anions across cellular membranes. By doing so, PAC plays an important role in both cellular physiology (endosome acidification) and diseases associated with tissue acidosis (acid-induced cell death). Despite the available structural information, how proton binding in the extracellular domain (ECD) leads to PAC channel opening remains largely unknown. Here, through comprehensive mutagenesis and electrophysiological studies, we identified several critical titratable residues, including two histidine residues (H130 and H131) and an aspartic acid residue (D269) at the distal end of the ECD, together with the previously characterized H98 at the transmembrane domain–ECD interface, as potential pH sensors for human PAC. Mutations of these residues resulted in significant changes in pH sensitivity. Some combined mutants also exhibited large basal PAC channel activities at neutral pH. By combining molecular dynamics simulations with structural and functional analysis, we further found that the β12 strand at the intersubunit interface and the associated “joint region” connecting the upper and lower ECDs allosterically regulate the proton-dependent PAC activation. Our studies suggest a distinct pH-sensing and gating mechanism of this new family of ion channels sensitive to acidic environment. National Academy of Sciences 2022-07-25 2022-08-02 /pmc/articles/PMC9351481/ /pubmed/35878032 http://dx.doi.org/10.1073/pnas.2200727119 Text en Copyright © 2022 the Author(s). Published by PNAS https://creativecommons.org/licenses/by-nc-nd/4.0/This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) .
spellingShingle Biological Sciences
Osei-Owusu, James
Kots, Ekaterina
Ruan, Zheng
Mihaljević, Ljubica
Chen, Kevin Hong
Tamhaney, Ami
Ye, Xinyu
Lü, Wei
Weinstein, Harel
Qiu, Zhaozhu
Molecular determinants of pH sensing in the proton-activated chloride channel
title Molecular determinants of pH sensing in the proton-activated chloride channel
title_full Molecular determinants of pH sensing in the proton-activated chloride channel
title_fullStr Molecular determinants of pH sensing in the proton-activated chloride channel
title_full_unstemmed Molecular determinants of pH sensing in the proton-activated chloride channel
title_short Molecular determinants of pH sensing in the proton-activated chloride channel
title_sort molecular determinants of ph sensing in the proton-activated chloride channel
topic Biological Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9351481/
https://www.ncbi.nlm.nih.gov/pubmed/35878032
http://dx.doi.org/10.1073/pnas.2200727119
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