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Functional interactions of voltage sensor charges with an S2 hydrophobic plug in hERG channels

Human ether-à-go-go–related gene (hERG, Kv11.1) potassium channels have unusually slow activation and deactivation kinetics. It has been suggested that, in fast-activating Shaker channels, a highly conserved Phe residue (F290) in the S2 segment forms a putative gating charge transfer center that int...

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Autores principales: Cheng, Yen May, Hull, Christina M., Niven, Christine M., Qi, Ji, Allard, Charlene R., Claydon, Tom W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3753600/
https://www.ncbi.nlm.nih.gov/pubmed/23980197
http://dx.doi.org/10.1085/jgp.201310992
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author Cheng, Yen May
Hull, Christina M.
Niven, Christine M.
Qi, Ji
Allard, Charlene R.
Claydon, Tom W.
author_facet Cheng, Yen May
Hull, Christina M.
Niven, Christine M.
Qi, Ji
Allard, Charlene R.
Claydon, Tom W.
author_sort Cheng, Yen May
collection PubMed
description Human ether-à-go-go–related gene (hERG, Kv11.1) potassium channels have unusually slow activation and deactivation kinetics. It has been suggested that, in fast-activating Shaker channels, a highly conserved Phe residue (F290) in the S2 segment forms a putative gating charge transfer center that interacts with S4 gating charges, i.e., R362 (R1) and K374 (K5), and catalyzes their movement across the focused electric field. F290 is conserved in hERG (F463), but the relevant residues in the hERG S4 are reversed, i.e., K525 (K1) and R537 (R5), and there is an extra positive charge adjacent to R537 (i.e., K538). We have examined whether hERG channels possess a transfer center similar to that described in Shaker and if these S4 charge differences contribute to slow gating in hERG channels. Of five hERG F463 hydrophobic substitutions tested, F463W and F463Y shifted the conductance–voltage (G-V) relationship to more depolarized potentials and dramatically slowed channel activation. With the S4 residue reversals (i.e., K525, R537) taken into account, the closed state stabilization by F463W is consistent with a role for F463 that is similar to that described for F290 in Shaker. As predicted from results with Shaker, the hERG K525R mutation destabilized the closed state. However, hERG R537K did not stabilize the open state as predicted. Instead, we found the neighboring K538 residue to be critical for open state stabilization, as K538R dramatically slowed and right-shifted the voltage dependence of activation. Finally, double mutant cycle analysis on the G-V curves of F463W/K525R and F463W/K538R double mutations suggests that F463 forms functional interactions with K525 and K538 in the S4 segment. Collectively, these data suggest a role for F463 in mediating closed–open equilibria, similar to that proposed for F290 in Shaker channels.
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spelling pubmed-37536002014-03-01 Functional interactions of voltage sensor charges with an S2 hydrophobic plug in hERG channels Cheng, Yen May Hull, Christina M. Niven, Christine M. Qi, Ji Allard, Charlene R. Claydon, Tom W. J Gen Physiol Research Articles Human ether-à-go-go–related gene (hERG, Kv11.1) potassium channels have unusually slow activation and deactivation kinetics. It has been suggested that, in fast-activating Shaker channels, a highly conserved Phe residue (F290) in the S2 segment forms a putative gating charge transfer center that interacts with S4 gating charges, i.e., R362 (R1) and K374 (K5), and catalyzes their movement across the focused electric field. F290 is conserved in hERG (F463), but the relevant residues in the hERG S4 are reversed, i.e., K525 (K1) and R537 (R5), and there is an extra positive charge adjacent to R537 (i.e., K538). We have examined whether hERG channels possess a transfer center similar to that described in Shaker and if these S4 charge differences contribute to slow gating in hERG channels. Of five hERG F463 hydrophobic substitutions tested, F463W and F463Y shifted the conductance–voltage (G-V) relationship to more depolarized potentials and dramatically slowed channel activation. With the S4 residue reversals (i.e., K525, R537) taken into account, the closed state stabilization by F463W is consistent with a role for F463 that is similar to that described for F290 in Shaker. As predicted from results with Shaker, the hERG K525R mutation destabilized the closed state. However, hERG R537K did not stabilize the open state as predicted. Instead, we found the neighboring K538 residue to be critical for open state stabilization, as K538R dramatically slowed and right-shifted the voltage dependence of activation. Finally, double mutant cycle analysis on the G-V curves of F463W/K525R and F463W/K538R double mutations suggests that F463 forms functional interactions with K525 and K538 in the S4 segment. Collectively, these data suggest a role for F463 in mediating closed–open equilibria, similar to that proposed for F290 in Shaker channels. The Rockefeller University Press 2013-09 /pmc/articles/PMC3753600/ /pubmed/23980197 http://dx.doi.org/10.1085/jgp.201310992 Text en © 2013 Cheng 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.rupress.org/terms). 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 Research Articles
Cheng, Yen May
Hull, Christina M.
Niven, Christine M.
Qi, Ji
Allard, Charlene R.
Claydon, Tom W.
Functional interactions of voltage sensor charges with an S2 hydrophobic plug in hERG channels
title Functional interactions of voltage sensor charges with an S2 hydrophobic plug in hERG channels
title_full Functional interactions of voltage sensor charges with an S2 hydrophobic plug in hERG channels
title_fullStr Functional interactions of voltage sensor charges with an S2 hydrophobic plug in hERG channels
title_full_unstemmed Functional interactions of voltage sensor charges with an S2 hydrophobic plug in hERG channels
title_short Functional interactions of voltage sensor charges with an S2 hydrophobic plug in hERG channels
title_sort functional interactions of voltage sensor charges with an s2 hydrophobic plug in herg channels
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3753600/
https://www.ncbi.nlm.nih.gov/pubmed/23980197
http://dx.doi.org/10.1085/jgp.201310992
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