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Conformational dynamics of the KcsA potassium channel governs gating properties.

ABSTRACT: 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.

SUBMITTER: Baker KA

PROVIDER: S-EPMC3525321 | biostudies-literature | 2007 Nov

REPOSITORIES: biostudies-literature

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Conformational dynamics of the KcsA potassium channel governs gating properties.

Baker Kent A KA Tzitzilonis Christos C Kwiatkowski Witek W Choe Senyon S Riek Roland R

Nature structural & molecular biology 20071007 11

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, close ...[more]

PMID: 17922011

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