Cargando…
Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles
The process of ion channel gating—opening and closing—involves local and global structural changes in the channel in response to external stimuli. Conformational changes depend on the energetic landscape that underlies the transition between closed and open states, which plays a key role in ion chan...
Autores principales: | , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
2016
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4969796/ https://www.ncbi.nlm.nih.gov/pubmed/27432996 http://dx.doi.org/10.1085/jgp.201611602 |
_version_ | 1782445844634533888 |
---|---|
author | Kim, Dorothy M. Dikiy, Igor Upadhyay, Vikrant Posson, David J. Eliezer, David Nimigean, Crina M. |
author_facet | Kim, Dorothy M. Dikiy, Igor Upadhyay, Vikrant Posson, David J. Eliezer, David Nimigean, Crina M. |
author_sort | Kim, Dorothy M. |
collection | PubMed |
description | The process of ion channel gating—opening and closing—involves local and global structural changes in the channel in response to external stimuli. Conformational changes depend on the energetic landscape that underlies the transition between closed and open states, which plays a key role in ion channel gating. For the prokaryotic, pH-gated potassium channel KcsA, closed and open states have been extensively studied using structural and functional methods, but the dynamics within each of these functional states as well as the transition between them is not as well understood. In this study, we used solution nuclear magnetic resonance (NMR) spectroscopy to investigate the conformational transitions within specific functional states of KcsA. We incorporated KcsA channels into lipid bicelles and stabilized them into a closed state by using either phosphatidylcholine lipids, known to favor the closed channel, or mutations designed to trap the channel shut by disulfide cross-linking. A distinct state, consistent with an open channel, was uncovered by the addition of cardiolipin lipids. Using selective amino acid labeling at locations within the channel that are known to move during gating, we observed at least two different slowly interconverting conformational states for both closed and open channels. The pH dependence of these conformations and the predictable disruptions to this dependence observed in mutant channels with altered pH sensing highlight the importance of conformational heterogeneity for KcsA gating. |
format | Online Article Text |
id | pubmed-4969796 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2016 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-49697962017-02-01 Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles Kim, Dorothy M. Dikiy, Igor Upadhyay, Vikrant Posson, David J. Eliezer, David Nimigean, Crina M. J Gen Physiol Research Articles The process of ion channel gating—opening and closing—involves local and global structural changes in the channel in response to external stimuli. Conformational changes depend on the energetic landscape that underlies the transition between closed and open states, which plays a key role in ion channel gating. For the prokaryotic, pH-gated potassium channel KcsA, closed and open states have been extensively studied using structural and functional methods, but the dynamics within each of these functional states as well as the transition between them is not as well understood. In this study, we used solution nuclear magnetic resonance (NMR) spectroscopy to investigate the conformational transitions within specific functional states of KcsA. We incorporated KcsA channels into lipid bicelles and stabilized them into a closed state by using either phosphatidylcholine lipids, known to favor the closed channel, or mutations designed to trap the channel shut by disulfide cross-linking. A distinct state, consistent with an open channel, was uncovered by the addition of cardiolipin lipids. Using selective amino acid labeling at locations within the channel that are known to move during gating, we observed at least two different slowly interconverting conformational states for both closed and open channels. The pH dependence of these conformations and the predictable disruptions to this dependence observed in mutant channels with altered pH sensing highlight the importance of conformational heterogeneity for KcsA gating. The Rockefeller University Press 2016-08 /pmc/articles/PMC4969796/ /pubmed/27432996 http://dx.doi.org/10.1085/jgp.201611602 Text en © 2016 Kim 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 Kim, Dorothy M. Dikiy, Igor Upadhyay, Vikrant Posson, David J. Eliezer, David Nimigean, Crina M. Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles |
title | Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles |
title_full | Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles |
title_fullStr | Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles |
title_full_unstemmed | Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles |
title_short | Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles |
title_sort | conformational heterogeneity in closed and open states of the kcsa potassium channel in lipid bicelles |
topic | Research Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4969796/ https://www.ncbi.nlm.nih.gov/pubmed/27432996 http://dx.doi.org/10.1085/jgp.201611602 |
work_keys_str_mv | AT kimdorothym conformationalheterogeneityinclosedandopenstatesofthekcsapotassiumchannelinlipidbicelles AT dikiyigor conformationalheterogeneityinclosedandopenstatesofthekcsapotassiumchannelinlipidbicelles AT upadhyayvikrant conformationalheterogeneityinclosedandopenstatesofthekcsapotassiumchannelinlipidbicelles AT possondavidj conformationalheterogeneityinclosedandopenstatesofthekcsapotassiumchannelinlipidbicelles AT eliezerdavid conformationalheterogeneityinclosedandopenstatesofthekcsapotassiumchannelinlipidbicelles AT nimigeancrinam conformationalheterogeneityinclosedandopenstatesofthekcsapotassiumchannelinlipidbicelles |