Inactivation of the KcsA potassium channel explored with heterotetramers.
The tetrameric prokaryotic potassium channel KcsA is activated by protons acting on the intracellular aspect of the protein and inactivated through conformational changes in the selectivity filter. Inactivation is modulated by a network of interactions within each protomer between the pore helix and residues at the external entrance of the channel. Inactivation is suppressed by the E71A mutation, which perturbs the stability of this network. Here, cell-free protein synthesis followed by protein purification by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to produce heterotetramers of KcsA that contain different combinations of wild-type and E71A subunits. Single-channel recordings from these heterotetramers reveal how the network of interactions in individual protomers affects ionic conduction and channel inactivation, suggesting that the latter is a cooperative process.
Rotem
Dvir
D
Department of Chemistry, University of Oxford, Oxford OX1 3TA, England, UK.
Mason
Amy
A
Bayley
Hagan
H
D001426:Bacterial Proteins / Q000737:chemistry*; D015640:Ion Channel Gating; D008051:Lipid Bilayers / Q000737:chemistry*; D015221:Potassium Channels / Q000737:chemistry*; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D008051:Lipid Bilayers; D015221:Potassium Channels; C107790:prokaryotic potassium channel