title: Electrostatic tuning of ion conductance in potassium channels.
abstract: Members of the K(+) channel family display remarkable conservation of sequence and structure of the ion selectivity filter, whereas the rates of K(+) turnover vary widely within the family. Here we show that channel conductance is strongly influenced by charge at the channel's intracellular mouth. Introduction of a ring of negative charges at this position in KcsA, a bacterial K(+) channel, augments the conductance in a pH-dependent manner. These results are explained by a simple electrostatic effect based on known channel structures, where the negative charges serve to alter the electrical potential at the inner mouth and, thus, to increase the local K(+) concentration. In addition, removal of the conserved negative charges at equivalent positions in a high-conductance eukaryotic K(+) channel leads to a decrease in conductance.
authors.affiliation: Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA.
authors.forename: Crina M
authors.initials: CM
authors.lastname: Nimigean
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Chappie
authors.forename: Christopher
authors.initials: C
authors.lastname: Miller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004553:Electric Conductivity; D004926:Escherichia coli / Q000378:metabolism; D015640:Ion Channel Gating / Q000235:genetics / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D021122:Protein Subunits; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D014982:Xenopus laevis
chemical_list: D001426:Bacterial Proteins; D015221:Potassium Channels; D021122:Protein Subunits; C107790:prokaryotic potassium channel