Cargando…

Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction

The mechanism of ion conduction by potassium channels is one of the central issues in physiology. In particular, it is still unclear how the ion concentration and the membrane voltage drive ion conduction. We have investigated the dynamics of the ion conduction processes in the Kv1.2 pore domain, by...

Descripción completa

Detalles Bibliográficos
Autores principales: Kasahara, Kota, Shirota, Matsuyuki, Kinoshita, Kengo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4780791/
https://www.ncbi.nlm.nih.gov/pubmed/26950215
http://dx.doi.org/10.1371/journal.pone.0150716
_version_ 1782419809262108672
author Kasahara, Kota
Shirota, Matsuyuki
Kinoshita, Kengo
author_facet Kasahara, Kota
Shirota, Matsuyuki
Kinoshita, Kengo
author_sort Kasahara, Kota
collection PubMed
description The mechanism of ion conduction by potassium channels is one of the central issues in physiology. In particular, it is still unclear how the ion concentration and the membrane voltage drive ion conduction. We have investigated the dynamics of the ion conduction processes in the Kv1.2 pore domain, by molecular dynamics (MD) simulations with several different voltages and ion concentrations. By focusing on the detailed ion movements through the pore including selectivity filter (SF) and cavity, we found two major conduction mechanisms, called the III-IV-III and III-II-III mechanisms, and the balance between the ion concentration and the voltage determines the mechanism preference. In the III-IV-III mechanism, the outermost ion in the pore is pushed out by a new ion coming from the intracellular fluid, and four-ion states were transiently observed. In the III-II-III mechanism, the outermost ion is pulled out first, without pushing by incoming ions. Increases in the ion concentration and voltage accelerated ion conductions, but their mechanisms were different. The increase in the ion concentrations facilitated the III-IV-III conductions, while the higher voltages increased the III-II-III conductions, indicating that the pore domain of potassium channels permeates ions by using two different driving forces: a push by intracellular ions and a pull by voltage.
format Online
Article
Text
id pubmed-4780791
institution National Center for Biotechnology Information
language English
publishDate 2016
publisher Public Library of Science
record_format MEDLINE/PubMed
spelling pubmed-47807912016-03-23 Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction Kasahara, Kota Shirota, Matsuyuki Kinoshita, Kengo PLoS One Research Article The mechanism of ion conduction by potassium channels is one of the central issues in physiology. In particular, it is still unclear how the ion concentration and the membrane voltage drive ion conduction. We have investigated the dynamics of the ion conduction processes in the Kv1.2 pore domain, by molecular dynamics (MD) simulations with several different voltages and ion concentrations. By focusing on the detailed ion movements through the pore including selectivity filter (SF) and cavity, we found two major conduction mechanisms, called the III-IV-III and III-II-III mechanisms, and the balance between the ion concentration and the voltage determines the mechanism preference. In the III-IV-III mechanism, the outermost ion in the pore is pushed out by a new ion coming from the intracellular fluid, and four-ion states were transiently observed. In the III-II-III mechanism, the outermost ion is pulled out first, without pushing by incoming ions. Increases in the ion concentration and voltage accelerated ion conductions, but their mechanisms were different. The increase in the ion concentrations facilitated the III-IV-III conductions, while the higher voltages increased the III-II-III conductions, indicating that the pore domain of potassium channels permeates ions by using two different driving forces: a push by intracellular ions and a pull by voltage. Public Library of Science 2016-03-07 /pmc/articles/PMC4780791/ /pubmed/26950215 http://dx.doi.org/10.1371/journal.pone.0150716 Text en © 2016 Kasahara et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Kasahara, Kota
Shirota, Matsuyuki
Kinoshita, Kengo
Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction
title Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction
title_full Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction
title_fullStr Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction
title_full_unstemmed Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction
title_short Ion Concentration- and Voltage-Dependent Push and Pull Mechanisms of Potassium Channel Ion Conduction
title_sort ion concentration- and voltage-dependent push and pull mechanisms of potassium channel ion conduction
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4780791/
https://www.ncbi.nlm.nih.gov/pubmed/26950215
http://dx.doi.org/10.1371/journal.pone.0150716
work_keys_str_mv AT kasaharakota ionconcentrationandvoltagedependentpushandpullmechanismsofpotassiumchannelionconduction
AT shirotamatsuyuki ionconcentrationandvoltagedependentpushandpullmechanismsofpotassiumchannelionconduction
AT kinoshitakengo ionconcentrationandvoltagedependentpushandpullmechanismsofpotassiumchannelionconduction