7M2H image
Entry Detail
PDB ID:
7M2H
Title:
Structural Snapshots of Intermediates in the Gating of a K+ Channel
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2021-03-16
Release Date:
2021-10-27
Method Details:
Experimental Method:
Resolution:
2.64 Å
R-Value Free:
0.26
R-Value Work:
0.23
R-Value Observed:
0.23
Space Group:
P 4
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Fab heavy chain
Chain IDs:A, D
Chain Length:219
Number of Molecules:2
Biological Source:Mus musculus
Polymer Type:polypeptide(L)
Description:Fab light chain
Chain IDs:B, E
Chain Length:212
Number of Molecules:2
Biological Source:Mus musculus
Polymer Type:polypeptide(L)
Description:pH-gated potassium channel KcsA
Chain IDs:C, F
Chain Length:125
Number of Molecules:2
Biological Source:Streptomyces lividans
Primary Citation
Structures of Gating Intermediates in a K + channell.
J.Mol.Biol. 433 167296 167296 (2021)
PMID: 34627789 DOI: 10.1016/j.jmb.2021.167296

Abstact

Regulation of ion conduction through the pore of a K+ channel takes place through the coordinated action of the activation gate at the bundle crossing of the inner helices and the inactivation gate located at the selectivity filter. The mechanism of allosteric coupling of these gates is of key interest. Here we report new insights into this allosteric coupling mechanism from studies on a W67F mutant of the KcsA channel. W67 is in the pore helix and is highly conserved in K+ channels. The KcsA W67F channel shows severely reduced inactivation and an enhanced rate of activation. We use continuous wave EPR spectroscopy to establish that the KcsA W67F channel shows an altered pH dependence of activation. Structural studies on the W67F channel provide the structures of two intermediate states: a pre- open state and a pre-inactivated state of the KcsA channel. These structures highlight key nodes in the allosteric pathway. The structure of the KcsA W67F channel with the activation gate open shows altered ion occupancy at the second ion binding site (S2) in the selectivity filter. This finding in combination with previous studies strongly support a requirement for ion occupancy at the S2 site for the channel to inactivate.

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