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hERG Gating Microdomains Defined by S6 Mutagenesis and Molecular Modeling

Human ether-à-go-go–related gene (hERG) channels mediate cardiac repolarization and bind drugs that can cause acquired long QT syndrome and life-threatening arrhythmias. Drugs bind in the vestibule formed by the S6 transmembrane domain, which also contains the activation gate that traps drugs in the...

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Autores principales: Wynia-Smith, Sarah L., Gillian-Daniel, Anne Lynn, Satyshur, Kenneth A., Robertson, Gail A.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2571969/
https://www.ncbi.nlm.nih.gov/pubmed/18955593
http://dx.doi.org/10.1085/jgp.200810083
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author Wynia-Smith, Sarah L.
Gillian-Daniel, Anne Lynn
Satyshur, Kenneth A.
Robertson, Gail A.
author_facet Wynia-Smith, Sarah L.
Gillian-Daniel, Anne Lynn
Satyshur, Kenneth A.
Robertson, Gail A.
author_sort Wynia-Smith, Sarah L.
collection PubMed
description Human ether-à-go-go–related gene (hERG) channels mediate cardiac repolarization and bind drugs that can cause acquired long QT syndrome and life-threatening arrhythmias. Drugs bind in the vestibule formed by the S6 transmembrane domain, which also contains the activation gate that traps drugs in the vestibule and contributes to their efficacy of block. Although drug-binding residues have been identified, we know little about the roles of specific S6 residues in gating. We introduced cysteine mutations into the hERG channel S6 domain and measured mutational effects on the steady-state distribution and kinetics of transitions between the closed and open states. Energy-minimized molecular models based on the crystal structures of rKv1.2 (open state) and MlotiK1 and KcsA (closed state) provided structural contexts for evaluating mutant residues. The majority of mutations slowed deactivation, shifted conductance voltage curves to more negative potentials, or conferred a constitutive conductance over voltages that normally cause the channel to close. At the most intracellular extreme of the S6 region, Q664, Y667, and S668 were especially sensitive and together formed a ringed domain that occludes the pore in the closed state model. In contrast, mutation of S660, more than a full helical turn away and corresponding by alignment to a critical Shaker gate residue (V478), had little effect on gating. Multiple substitutions of chemically distinct amino acids at the adjacent V659 suggested that, upon closing, the native V659 side chain moves into a hydrophobic pocket but likely does not form the occluding gate itself. Overall, the study indicated that S6 mutagenesis disrupts the energetics primarily of channel closing and identified several residues critical for this process in the native channel.
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spelling pubmed-25719692009-05-01 hERG Gating Microdomains Defined by S6 Mutagenesis and Molecular Modeling Wynia-Smith, Sarah L. Gillian-Daniel, Anne Lynn Satyshur, Kenneth A. Robertson, Gail A. J Gen Physiol Articles Human ether-à-go-go–related gene (hERG) channels mediate cardiac repolarization and bind drugs that can cause acquired long QT syndrome and life-threatening arrhythmias. Drugs bind in the vestibule formed by the S6 transmembrane domain, which also contains the activation gate that traps drugs in the vestibule and contributes to their efficacy of block. Although drug-binding residues have been identified, we know little about the roles of specific S6 residues in gating. We introduced cysteine mutations into the hERG channel S6 domain and measured mutational effects on the steady-state distribution and kinetics of transitions between the closed and open states. Energy-minimized molecular models based on the crystal structures of rKv1.2 (open state) and MlotiK1 and KcsA (closed state) provided structural contexts for evaluating mutant residues. The majority of mutations slowed deactivation, shifted conductance voltage curves to more negative potentials, or conferred a constitutive conductance over voltages that normally cause the channel to close. At the most intracellular extreme of the S6 region, Q664, Y667, and S668 were especially sensitive and together formed a ringed domain that occludes the pore in the closed state model. In contrast, mutation of S660, more than a full helical turn away and corresponding by alignment to a critical Shaker gate residue (V478), had little effect on gating. Multiple substitutions of chemically distinct amino acids at the adjacent V659 suggested that, upon closing, the native V659 side chain moves into a hydrophobic pocket but likely does not form the occluding gate itself. Overall, the study indicated that S6 mutagenesis disrupts the energetics primarily of channel closing and identified several residues critical for this process in the native channel. The Rockefeller University Press 2008-11 /pmc/articles/PMC2571969/ /pubmed/18955593 http://dx.doi.org/10.1085/jgp.200810083 Text en © 2008 Wynia-Smith et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jgp.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
spellingShingle Articles
Wynia-Smith, Sarah L.
Gillian-Daniel, Anne Lynn
Satyshur, Kenneth A.
Robertson, Gail A.
hERG Gating Microdomains Defined by S6 Mutagenesis and Molecular Modeling
title hERG Gating Microdomains Defined by S6 Mutagenesis and Molecular Modeling
title_full hERG Gating Microdomains Defined by S6 Mutagenesis and Molecular Modeling
title_fullStr hERG Gating Microdomains Defined by S6 Mutagenesis and Molecular Modeling
title_full_unstemmed hERG Gating Microdomains Defined by S6 Mutagenesis and Molecular Modeling
title_short hERG Gating Microdomains Defined by S6 Mutagenesis and Molecular Modeling
title_sort herg gating microdomains defined by s6 mutagenesis and molecular modeling
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2571969/
https://www.ncbi.nlm.nih.gov/pubmed/18955593
http://dx.doi.org/10.1085/jgp.200810083
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