%0 Journal Article
%A Dreyer, Jens
%A Strodel, Paul
%A Ippoliti, Emiliano
%A Finnerty, Justin
%A Eisenberg, Bob
%A Carloni, Paolo
%T Ion Permeation in the NanC Porin from Escherichia coli: Free Energy Calculations along Pathways Identified by Coarse-Grain Simulations
%J The journal of physical chemistry  / B
%V 117
%N 43
%@ 1520-5207
%C Washington, DC
%I Soc.
%M FZJ-2015-03609
%P 13534 - 13542
%D 2013
%X Using the X-ray structure of a recently discovered bacterial protein, the N-acetylneuraminic acid-inducible channel (NanC), we investigate computationally K+ and Cl– ions’ permeation. We identify ion permeation pathways that are likely to be populated using coarse-grain Monte Carlo simulations. Next, we use these pathways as reaction coordinates for umbrella sampling-based free energy simulations. We find distinct tubelike pathways connecting specific binding sites for K+ and, more pronounced, for Cl– ions. Both ions permeate the porin preserving almost all of their first hydration shell. The calculated free energy barriers are G# ≈ 4 kJ/mol and G# ≈ 8 kJ/mol for Cl– and K+, respectively. Within the approximations associated with these values, discussed in detail in this work, we suggest that the porin is slightly selective for Cl– versus K+. Our suggestion is consistent with the experimentally observed weak Cl– over K+ selectivity. A rationale for the latter is suggested by a comparison with previous calculations on strongly anion selective porins.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000326608500016
%$ pmid:24147565
%R 10.1021/jp4081838
%U https://juser.fz-juelich.de/record/201304