6O9V image
Entry Detail
PDB ID:
6O9V
Title:
KirBac3.1 mutant at a resolution of 3.1 Angstroms
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2019-03-15
Release Date:
2020-05-27
Method Details:
Experimental Method:
Resolution:
3.09 Å
R-Value Free:
0.29
R-Value Work:
0.24
R-Value Observed:
0.25
Space Group:
P 21 21 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Inward rectifier potassium channel Kirbac3.1
Mutations:C71V, C119V, S129C, F135C, C262S
Chain IDs:A, B
Chain Length:301
Number of Molecules:2
Biological Source:Magnetospirillum magnetotacticum
Primary Citation
A constricted opening in Kir channels does not impede potassium conduction.
Nat Commun 11 3024 3024 (2020)
PMID: 32541684 DOI: 10.1038/s41467-020-16842-0

Abstact

The canonical mechanistic model explaining potassium channel gating is of a conformational change that alternately dilates and constricts a collar-like intracellular entrance to the pore. It is based on the premise that K+ ions maintain a complete hydration shell while passing between the transmembrane cavity and cytosol, which must be accommodated. To put the canonical model to the test, we locked the conformation of a Kir K+ channel to prevent widening of the narrow collar. Unexpectedly, conduction was unimpaired in the locked channels. In parallel, we employed all-atom molecular dynamics to simulate K+ ions moving along the conduction pathway between the lower cavity and cytosol. During simulations, the constriction did not significantly widen. Instead, transient loss of some water molecules facilitated K+ permeation through the collar. The low free energy barrier to partial dehydration in the absence of conformational change indicates Kir channels are not gated by the canonical mechanism.

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