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Intermediate state trapping of a voltage sensor
Voltage sensor domains (VSDs) regulate ion channels and enzymes by undergoing conformational changes depending on membrane electrical signals. The molecular mechanisms underlying the VSD transitions are not fully understood. Here, we show that some mutations of I241 in the S1 segment of the Shaker K...
Autores principales: | , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
2012
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3514728/ https://www.ncbi.nlm.nih.gov/pubmed/23183699 http://dx.doi.org/10.1085/jgp.201210827 |
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author | Lacroix, Jérôme J. Pless, Stephan A. Maragliano, Luca Campos, Fabiana V. Galpin, Jason D. Ahern, Christopher A. Roux, Benoît Bezanilla, Francisco |
author_facet | Lacroix, Jérôme J. Pless, Stephan A. Maragliano, Luca Campos, Fabiana V. Galpin, Jason D. Ahern, Christopher A. Roux, Benoît Bezanilla, Francisco |
author_sort | Lacroix, Jérôme J. |
collection | PubMed |
description | Voltage sensor domains (VSDs) regulate ion channels and enzymes by undergoing conformational changes depending on membrane electrical signals. The molecular mechanisms underlying the VSD transitions are not fully understood. Here, we show that some mutations of I241 in the S1 segment of the Shaker Kv channel positively shift the voltage dependence of the VSD movement and alter the functional coupling between VSD and pore domains. Among the I241 mutants, I241W immobilized the VSD movement during activation and deactivation, approximately halfway between the resting and active states, and drastically shifted the voltage activation of the ionic conductance. This phenotype, which is consistent with a stabilization of an intermediate VSD conformation by the I241W mutation, was diminished by the charge-conserving R2K mutation but not by the charge-neutralizing R2Q mutation. Interestingly, most of these effects were reproduced by the F244W mutation located one helical turn above I241. Electrophysiology recordings using nonnatural indole derivatives ruled out the involvement of cation-Π interactions for the effects of the Trp inserted at positions I241 and F244 on the channel’s conductance, but showed that the indole nitrogen was important for the I241W phenotype. Insight into the molecular mechanisms responsible for the stabilization of the intermediate state were investigated by creating in silico the mutations I241W, I241W/R2K, and F244W in intermediate conformations obtained from a computational VSD transition pathway determined using the string method. The experimental results and computational analysis suggest that the phenotype of I241W may originate in the formation of a hydrogen bond between the indole nitrogen atom and the backbone carbonyl of R2. This work provides new information on intermediate states in voltage-gated ion channels with an approach that produces minimum chemical perturbation. |
format | Online Article Text |
id | pubmed-3514728 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2012 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-35147282013-06-01 Intermediate state trapping of a voltage sensor Lacroix, Jérôme J. Pless, Stephan A. Maragliano, Luca Campos, Fabiana V. Galpin, Jason D. Ahern, Christopher A. Roux, Benoît Bezanilla, Francisco J Gen Physiol Article Voltage sensor domains (VSDs) regulate ion channels and enzymes by undergoing conformational changes depending on membrane electrical signals. The molecular mechanisms underlying the VSD transitions are not fully understood. Here, we show that some mutations of I241 in the S1 segment of the Shaker Kv channel positively shift the voltage dependence of the VSD movement and alter the functional coupling between VSD and pore domains. Among the I241 mutants, I241W immobilized the VSD movement during activation and deactivation, approximately halfway between the resting and active states, and drastically shifted the voltage activation of the ionic conductance. This phenotype, which is consistent with a stabilization of an intermediate VSD conformation by the I241W mutation, was diminished by the charge-conserving R2K mutation but not by the charge-neutralizing R2Q mutation. Interestingly, most of these effects were reproduced by the F244W mutation located one helical turn above I241. Electrophysiology recordings using nonnatural indole derivatives ruled out the involvement of cation-Π interactions for the effects of the Trp inserted at positions I241 and F244 on the channel’s conductance, but showed that the indole nitrogen was important for the I241W phenotype. Insight into the molecular mechanisms responsible for the stabilization of the intermediate state were investigated by creating in silico the mutations I241W, I241W/R2K, and F244W in intermediate conformations obtained from a computational VSD transition pathway determined using the string method. The experimental results and computational analysis suggest that the phenotype of I241W may originate in the formation of a hydrogen bond between the indole nitrogen atom and the backbone carbonyl of R2. This work provides new information on intermediate states in voltage-gated ion channels with an approach that produces minimum chemical perturbation. The Rockefeller University Press 2012-12 /pmc/articles/PMC3514728/ /pubmed/23183699 http://dx.doi.org/10.1085/jgp.201210827 Text en © 2012 Lacroix 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 | Article Lacroix, Jérôme J. Pless, Stephan A. Maragliano, Luca Campos, Fabiana V. Galpin, Jason D. Ahern, Christopher A. Roux, Benoît Bezanilla, Francisco Intermediate state trapping of a voltage sensor |
title | Intermediate state trapping of a voltage sensor |
title_full | Intermediate state trapping of a voltage sensor |
title_fullStr | Intermediate state trapping of a voltage sensor |
title_full_unstemmed | Intermediate state trapping of a voltage sensor |
title_short | Intermediate state trapping of a voltage sensor |
title_sort | intermediate state trapping of a voltage sensor |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3514728/ https://www.ncbi.nlm.nih.gov/pubmed/23183699 http://dx.doi.org/10.1085/jgp.201210827 |
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