Electrostatic tuning of ion conductance in potassium channels

Biochemistry. 2003 Aug 12;42(31):9263-8. doi: 10.1021/bi0348720.


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.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Electric Conductivity*
  • Escherichia coli / metabolism
  • Ion Channel Gating / genetics
  • Ion Channel Gating / physiology*
  • Membrane Potentials / physiology*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Oocytes / metabolism
  • Potassium Channels / genetics
  • Potassium Channels / metabolism*
  • Protein Conformation
  • Protein Subunits
  • Sequence Homology, Amino Acid
  • Static Electricity
  • Xenopus laevis


  • Bacterial Proteins
  • Potassium Channels
  • Protein Subunits
  • prokaryotic potassium channel