Cargando…

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...

Descripción completa

Detalles Bibliográficos
Autores principales: Banh, Richard, Cherny, Vladimir V., Morgan, Deri, Musset, Boris, Thomas, Sarah, Kulleperuma, Kethika, Smith, Susan M. E., Pomès, Régis, DeCoursey, Thomas E.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2019
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
_version_ 1783453095308558336
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
work_keys_str_mv AT banhrichard hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels
AT chernyvladimirv hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels
AT morganderi hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels
AT mussetboris hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels
AT thomassarah hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels
AT kulleperumakethika hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels
AT smithsusanme hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels
AT pomesregis hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels
AT decourseythomase hydrophobicgasketmutationproducesgatingporecurrentsinclosedhumanvoltagegatedprotonchannels