A microscopic view of ion conduction through the K+ channel
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
ID 57890
Author(s) Bernèche, Simon; Roux, Benoît
Author(s) at UniBasel Bernèche, Simon
Year 2003
Title A microscopic view of ion conduction through the K+ channel
Journal Proceedings of the National Academy of Sciences of the United States of America
Volume 100
Number 15
Pages / Article-Number 8644-8
Keywords molecular dynamics, Brownian dynamics, potential of mean force, membrane potential, Poisson-Boltzmann equation

Recent results from x-ray crystallography and molecular dynamics free-energy simulations have revealed the existence of a number of specific cation-binding sites disposed along the narrow pore of the K+ channel from Streptomyces lividans (KcsA), suggesting that K+ ions might literally "hop" in single file from one binding site to the next as permeation proceeds. In support of this view, it was found that the ion configurations correspond to energy wells of similar depth and that ion translocation is opposed only by small energy barriers. Although such features of the multiion potential energy surface are certainly essential for achieving a high throughput rate, diffusional and dissipative dynamical factors must also be taken into consideration to understand how rapid conduction of K+ is possible. To elucidate the mechanism of ion conduction, we established a framework theory enabling the direct simulation of nonequilibrium fluxes by extending the results of molecular dynamics over macroscopically long times. In good accord with experimental measurements, the simulated maximum conductance of the channel at saturating concentration is on the order of 550 and 360 pS for outward and inward ions flux, respectively, with a unidirectional flux-ratio exponent of 3. Analysis of the ion-conduction process reveals a lack of equivalence between the cation-binding sites in the selectivity filter.

Publisher National Academy of Sciences
ISSN/ISBN 0027-8424
edoc-URL http://edoc.unibas.ch/dok/A5249314
Full Text on edoc No
Digital Object Identifier DOI 10.1073/pnas.1431750100
PubMed ID http://www.ncbi.nlm.nih.gov/pubmed/12837936
ISI-Number WOS:000184371000011
Document type (ISI) Journal Article

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