6O9U

KirBac3.1 at a resolution of 2 Angstroms

Summary for 6O9U

• Entry DOI: 10.2210/pdb6o9u/pdb
• Descriptor: Inward rectifier potassium channel Kirbac3.1, trimethylamine oxide, POTASSIUM ION, ... (8 entities in total)
• Functional Keywords: membrane protein
• Biological source: Magnetospirillum magnetotacticum
• Total number of polymer chains: 1
• Total formula weight: 36373.18

Authors

Gulbis, J.M.,Clarke, O.B. (deposition date: 2019-03-15, release date: 2020-05-27, Last modification date: 2023-10-11)

Primary citation

Black, K.A.,He, S.,Jin, R.,Miller, D.M.,Bolla, J.R.,Clarke, O.B.,Johnson, P.,Windley, M.,Burns, C.J.,Hill, A.P.,Laver, D.,Robinson, C.V.,Smith, B.J.,Gulbis, J.M.
A constricted opening in Kir channels does not impede potassium conduction.
Nat Commun, 11:3024-3024, 2020

PubMed Abstract: 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.

PubMed: 32541684
DOI: 10.1038/s41467-020-16842-0

Experimental method

X-RAY DIFFRACTION (2 Å)