Conformational dynamics of the KcsA potassium channel governs gating properties

Nat Struct Mol Biol. 2007 Nov;14(11):1089-95. doi: 10.1038/nsmb1311. Epub 2007 Oct 7.


K+ channels conduct and regulate K+ flux across the cell membrane. Several crystal structures and biophysical studies of tetrameric ion channels have revealed many of the structural details of ion selectivity and gating. A narrow pore lined with four arrays of carbonyl groups is responsible for ion selectivity, whereas a conformational change of the four inner transmembrane helices (TM2) is involved in gating. We used NMR to examine full-length KcsA, a prototypical K+ channel, in its open, closed and intermediate states. These studies reveal that at least two conformational states exist both in the selectivity filter and near the C-terminal ends of the TM2 helices. In the ion-conducting open state, we observed rapid structural exchange between two conformations of the filter, presumably of low and high K+ affinity, respectively. Such measurements of millisecond-timescale dynamics reveal the basis for simultaneous ion selection and gating.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Crystallography, X-Ray
  • Hydrogen-Ion Concentration
  • Ion Channel Gating*
  • Molecular Sequence Data
  • Molecular Structure
  • Nuclear Magnetic Resonance, Biomolecular
  • Potassium / metabolism
  • Potassium Channels / chemistry*
  • Potassium Channels / genetics
  • Potassium Channels / metabolism*
  • Protein Structure, Quaternary*
  • Protein Structure, Secondary*
  • Streptomyces lividans / metabolism
  • Structure-Activity Relationship


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