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Hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels
The hydrophobic gasket (HG), a ring of hydrophobic amino acids in the voltage-sensing domain of most voltage-gated ion channels, forms a constriction between internal and external aqueous vestibules. Cationic Arg or Lys side chains lining the S4 helix move through this “gating pore” when the channel...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
National Academy of Sciences
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6754559/ https://www.ncbi.nlm.nih.gov/pubmed/31462498 http://dx.doi.org/10.1073/pnas.1905462116 |
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author | Banh, Richard Cherny, Vladimir V. Morgan, Deri Musset, Boris Thomas, Sarah Kulleperuma, Kethika Smith, Susan M. E. Pomès, Régis DeCoursey, Thomas E. |
author_facet | Banh, Richard Cherny, Vladimir V. Morgan, Deri Musset, Boris Thomas, Sarah Kulleperuma, Kethika Smith, Susan M. E. Pomès, Régis DeCoursey, Thomas E. |
author_sort | Banh, Richard |
collection | PubMed |
description | The hydrophobic gasket (HG), a ring of hydrophobic amino acids in the voltage-sensing domain of most voltage-gated ion channels, forms a constriction between internal and external aqueous vestibules. Cationic Arg or Lys side chains lining the S4 helix move through this “gating pore” when the channel opens. S4 movement may occur during gating of the human voltage-gated proton channel, hH(V)1, but proton current flows through the same pore in open channels. Here, we replaced putative HG residues with less hydrophobic residues or acidic Asp. Substitution of individuals, pairs, or all 3 HG positions did not impair proton selectivity. Evidently, the HG does not act as a secondary selectivity filter. However, 2 unexpected functions of the HG in H(V)1 were discovered. Mutating HG residues independently accelerated channel opening and compromised the closed state. Mutants exhibited open–closed gating, but strikingly, at negative voltages where “normal” gating produces a nonconducting closed state, the channel leaked protons. Closed-channel proton current was smaller than open-channel current and was inhibited by 10 μM Zn(2+). Extreme hyperpolarization produced a deeper closed state through a weakly voltage-dependent transition. We functionally identify the HG as Val(109), Phe(150), Val(177), and Val(178), which play a critical and exclusive role in preventing H(+) influx through closed channels. Molecular dynamics simulations revealed enhanced mobility of Arg(208) in mutants exhibiting H(+) leak. Mutation of HG residues produces gating pore currents reminiscent of several channelopathies. |
format | Online Article Text |
id | pubmed-6754559 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | National Academy of Sciences |
record_format | MEDLINE/PubMed |
spelling | pubmed-67545592019-10-01 Hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels Banh, Richard Cherny, Vladimir V. Morgan, Deri Musset, Boris Thomas, Sarah Kulleperuma, Kethika Smith, Susan M. E. Pomès, Régis DeCoursey, Thomas E. Proc Natl Acad Sci U S A PNAS Plus The hydrophobic gasket (HG), a ring of hydrophobic amino acids in the voltage-sensing domain of most voltage-gated ion channels, forms a constriction between internal and external aqueous vestibules. Cationic Arg or Lys side chains lining the S4 helix move through this “gating pore” when the channel opens. S4 movement may occur during gating of the human voltage-gated proton channel, hH(V)1, but proton current flows through the same pore in open channels. Here, we replaced putative HG residues with less hydrophobic residues or acidic Asp. Substitution of individuals, pairs, or all 3 HG positions did not impair proton selectivity. Evidently, the HG does not act as a secondary selectivity filter. However, 2 unexpected functions of the HG in H(V)1 were discovered. Mutating HG residues independently accelerated channel opening and compromised the closed state. Mutants exhibited open–closed gating, but strikingly, at negative voltages where “normal” gating produces a nonconducting closed state, the channel leaked protons. Closed-channel proton current was smaller than open-channel current and was inhibited by 10 μM Zn(2+). Extreme hyperpolarization produced a deeper closed state through a weakly voltage-dependent transition. We functionally identify the HG as Val(109), Phe(150), Val(177), and Val(178), which play a critical and exclusive role in preventing H(+) influx through closed channels. Molecular dynamics simulations revealed enhanced mobility of Arg(208) in mutants exhibiting H(+) leak. Mutation of HG residues produces gating pore currents reminiscent of several channelopathies. National Academy of Sciences 2019-09-17 2019-08-28 /pmc/articles/PMC6754559/ /pubmed/31462498 http://dx.doi.org/10.1073/pnas.1905462116 Text en Copyright © 2019 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by-nc-nd/4.0/ https://creativecommons.org/licenses/by-nc-nd/4.0/This open access 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 | PNAS Plus Banh, Richard Cherny, Vladimir V. Morgan, Deri Musset, Boris Thomas, Sarah Kulleperuma, Kethika Smith, Susan M. E. Pomès, Régis DeCoursey, Thomas E. Hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels |
title | Hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels |
title_full | Hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels |
title_fullStr | Hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels |
title_full_unstemmed | Hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels |
title_short | Hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels |
title_sort | hydrophobic gasket mutation produces gating pore currents in closed human voltage-gated proton channels |
topic | PNAS Plus |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6754559/ https://www.ncbi.nlm.nih.gov/pubmed/31462498 http://dx.doi.org/10.1073/pnas.1905462116 |
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