title: Polarization effects and charge transfer in the KcsA potassium channel.
abstract: The electronic structure of the selectivity filter of KcsA K(+) channel is investigated by density functional theory (DFT/BLYP) and QM/MM methods. The quantum part includes the selectivity filter, which is polarized by the electrostatic field of the environment treated with the Amber force field. The details of the electronic structure were investigated using the maximally localized Wannier function centers of charge and Bader's atoms in molecules charge analysis. Our results show that the channel backbone carbonyl groups are largely polarized and that there is a sizeable charge transfer from the backbone to the cations. These effects are expected to be important for an accurate description of the carbonyl groups and the ion-ion electrostatic repulsion, which have been proposed to play a central role for the selectivity mechanism of the channel [S.Y. Noskov, S. Berneche, B. Roux, Control of ion selectivity in potassium channels by electrostatic and dynamic properties of carbonyl ligands. Nature 431 (2004) 830-834].
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne EPFL, Institute of Chemical Sciences and Engineering, CH-1015 Lausanne, Switzerland.
authors.forename: Denis
authors.initials: D
authors.lastname: Bucher
authors.forename: Simone
authors.initials: S
authors.lastname: Raugei
authors.forename: Leonardo
authors.initials: L
authors.lastname: Guidoni
authors.forename: Matteo
authors.initials: M
authors.lastname: Dal Peraro
authors.forename: Ursula
authors.initials: U
authors.lastname: Rothlisberger
authors.forename: Paolo
authors.initials: P
authors.lastname: Carloni
authors.forename: Michael L
authors.initials: ML
authors.lastname: Klein
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D017136:Ion Transport; D008958:Models, Molecular; D011188:Potassium / Q000737:chemistry; D015221:Potassium Channels / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D001426:Bacterial Proteins; D015221:Potassium Channels; C107790:prokaryotic potassium channel; D011188:Potassium