Comparing the Temperature-Dependent Conductance of the Two Structurally Similar E. coli Porins OmpC and OmpF
- 1 May 2010
- journal article
- research article
- Published by Elsevier BV in Biophysical Journal
- Vol. 98 (9), 1830-1839
- https://doi.org/10.1016/j.bpj.2010.01.026
Abstract
The temperature-dependent ion conductance of OmpC, a major outer membrane channel of Escherichia coli, is predicted using all-atom molecular dynamics simulations and experimentally verified. To generalize previous results, OmpC is compared to its structural homolog OmpF at different KCl concentrations, pH values, and a broad temperature range. At low salt concentrations and up to room temperature, the molecular modeling predicts the experimental conductance accurately. At high salt concentrations above 1 M KCl and above room temperature, the simulations underestimate the conductance. Moreover, the temperature dependence of the channel conductance is different from that of the bulk, both in experiment and simulation, indicating a strong contribution of surface effects to the ion conductance. With respect to OmpC, subconductance levels can be observed in experiments only. Subconductance and gating levels can be clearly distinguished by their differences in conductance values and temperature-dependent behavior. With increasing temperature, the probability of a subconductance state to occur, increases, while the dwell time is decreased. The open probability, frequency, and dwell time of such states is largely pH- and KCl concentration-independent, while their amplitudes show a lower increase with increasing salt concentration than gating amplitudes. Voltage dependence of subconductance has been found to be negligible within the uncertainty of the measurements.Keywords
This publication has 48 references indexed in Scilit:
- Understanding Ion Conductance on a Molecular Level: An All-Atom Modeling of the Bacterial Porin OmpFBiophysical Journal, 2009
- Ionic Current Rectification through Silica NanoporesThe Journal of Physical Chemistry C, 2009
- The Membrane Potential and its Representation by a Constant Electric Field in Computer SimulationsBiophysical Journal, 2008
- Kinetics, Statistics, and Energetics of Lipid Membrane Electroporation Studied by Molecular Dynamics SimulationsBiophysical Journal, 2008
- Crystal structures of the OmpF porin: function in a colicin transloconThe EMBO Journal, 2008
- Outer membrane protein G: Engineering a quiet pore for biosensingProceedings of the National Academy of Sciences of the United States of America, 2008
- Polyamine Effects on Antibiotic Susceptibility in BacteriaAntimicrobial Agents and Chemotherapy, 2007
- Scalable molecular dynamics with NAMDJournal of Computational Chemistry, 2005
- All-Atom Empirical Potential for Molecular Modeling and Dynamics Studies of ProteinsThe Journal of Physical Chemistry B, 1998
- VMD: Visual molecular dynamicsJournal of Molecular Graphics, 1996