title: Electrostatic interactions and hydrogen bond dynamics in chloride  pumping by halorhodopsin.
abstract: Translocation of negatively charged ions across cell membranes by ion pumps raises the question as to how protein interactions control the location and dynamics of the ion. Here we address this question by performing extensive molecular dynamics simulations of wild type and mutant halorhodopsin, a seven-helical transmembrane protein that translocates chloride ions upon light absorption. We find that inter-helical hydrogen bonds mediated by a key arginine group largely govern the dynamics of the protein and water groups coordinating the chloride ion.
authors.affiliation: Departamento de Recursos de la Tierra, Universidad Autónoma Metropolitana-Lerma, Lerma de Villada, Estado de México 52005, México.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Jardón-Valadez
authors.affiliation: Theoretical Molecular Biophysics Department of Physics, Freie University Arnimallee 14, Berlin 14195, Germany. Electronic address: nbondar@zedat.fu-berlin.de.
authors.forename: Ana-Nicoleta
authors.initials: AN
authors.lastname: Bondar
authors.affiliation: Department of Chemistry, University of California, Irvine, CA 92697-2025, USA.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Tobias
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001120:Arginine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002712:Chlorides / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D006216:Halobacteriaceae / Q000235:genetics / Q000378:metabolism; D025602:Halorhodopsins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006860:Hydrogen Bonding; D017136:Ion Transport; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity
chemical_list: D019843:Archaeal Proteins; D002712:Chlorides; D025602:Halorhodopsins; D008051:Lipid Bilayers; D008565:Membrane Proteins; D001120:Arginine