TY  - JOUR
AU  - Dreyer, Jens
AU  - Strodel, Paul
AU  - Ippoliti, Emiliano
AU  - Finnerty, Justin
AU  - Eisenberg, Bob
AU  - Carloni, Paolo
TI  - Ion Permeation in the NanC Porin from Escherichia coli: Free Energy Calculations along Pathways Identified by Coarse-Grain Simulations
JO  - The journal of physical chemistry  / B
VL  - 117
IS  - 43
SN  - 1520-5207
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2015-03609
SP  - 13534 - 13542
PY  - 2013
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000326608500016
C6  - pmid:24147565
DO  - DOI:10.1021/jp4081838
UR  - https://juser.fz-juelich.de/record/201304
ER  -