Document Detail


Brownian dynamics simulation of ion flow through porin channels.
MedLine Citation:
PMID:  10600374     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Bacterial porins, which allow the passage of solutes across the outer bacterial membrane, are structurally well characterized. They therefore lend themselves to detailed studies of the determinants of ion flow through transmembraneous channels. In a comparative study, we have performed Brownian dynamics simulations to obtain statistically significant transfer efficiencies for cations and anions through matrix porin OmpF, osmoporin OmpK36, phosphoporin PhoE and two OmpF charge mutants. The simulations show that the electrostatic potential at the highly charged channel constriction serves to enhance ion permeability of either cations or anions, dependent on the type of porin. At the same time translocation of counterions is not severely impeded. At the constriction, cations and anions follow distinct trajectories, due to the segregation of basic and acidic protein residues. Simulated ion selectivity and relative conductance agree well with experimental values, and are dependent crucially on the charge constellation at the pore constriction. The experimentally observed decrease in ion selectivity and single channel conductance with increasing ionic strength is well reproduced and can be attributed to electrostatic shielding of the pore lining.
Authors:
T Schirmer; P S Phale
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of molecular biology     Volume:  294     ISSN:  0022-2836     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  1999 Dec 
Date Detail:
Created Date:  2000-01-11     Completed Date:  2000-01-11     Revised Date:  2009-11-03    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1159-67     Citation Subset:  IM    
Copyright Information:
Copyright 1999 Academic Press.
Affiliation:
Department of Structural Biology, Biozentrum, University of Basel, Basel, CH-4056, Switzerland.
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MeSH Terms
Descriptor/Qualifier:
Anions / metabolism
Bacterial Proteins*
Cations / metabolism
Computer Simulation*
Diffusion
Electric Conductivity
Electrophysiology
Escherichia coli Proteins
Hydrogen-Ion Concentration
Ion Channel Gating*
Models, Molecular
Mutation / genetics
Osmolar Concentration
Permeability
Porins / genetics,  metabolism*
Static Electricity
Substrate Specificity
Chemical
Reg. No./Substance:
0/Anions; 0/Bacterial Proteins; 0/Cations; 0/Escherichia coli Proteins; 0/OmpF protein; 0/OmpK36 protein, Klebsiella pneumoniae; 0/Porins; 85130-31-0/PhoE protein, E coli

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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