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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...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
National Academy of Sciences
2022
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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. |
format | Online Article Text |
id | pubmed-9351481 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | National Academy of Sciences |
record_format | MEDLINE/PubMed |
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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