|Title||Electrostatic tuning of ion conductance in potassium channels.|
|Publication Type||Journal Article|
|Year of Publication||2003|
|Authors||Nimigean CM, Chappie JS, Miller C|
|Date Published||2003 Aug 12|
|Keywords||Amino Acid Sequence, Animals, Bacterial Proteins, Electric Conductivity, Escherichia coli, Ion Channel Gating, Membrane Potentials, Molecular Sequence Data, Mutagenesis, Site-Directed, Oocytes, Potassium Channels, Protein Conformation, Protein Subunits, Sequence Homology, Amino Acid, Static Electricity, Xenopus laevis|
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.