[NMR paper] Conformational equilibrium shift underlies altered K+ channel gating as revealed by NMR.

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Conformational equilibrium shift underlies altered K+ channel gating as revealed by NMR.

Related Articles Conformational equilibrium shift underlies altered K+ channel gating as revealed by NMR.

Nat Commun. 2020 10 14;11(1):5168

Authors: Iwahashi Y, Toyama Y, Imai S, Itoh H, Osawa M, Inoue M, Shimada I

Abstract
The potassium ion (K+) channel plays a fundamental role in controlling K+ permeation across the cell membrane and regulating cellular excitabilities. Mutations in the transmembrane pore reportedly affect the gating transitions of K+ channels, and are associated with the onset of neural disorders. However, due to the lack of structural and dynamic insights into the functions of K+ channels, the structural mechanism by which these mutations cause K+ channel dysfunctions remains elusive. Here, we used nuclear magnetic resonance spectroscopy to investigate the structural mechanism underlying the decreased K+-permeation caused by disease-related mutations, using the prokaryotic K+ channel KcsA. We demonstrated that the conformational equilibrium in the transmembrane region is shifted toward the non-conductive state with the closed intracellular K+-gate in the disease-related mutant. We also demonstrated that this equilibrium shift is attributable to the additional steric contacts in the open-conductive structure, which are evoked by the increased side-chain bulkiness of the residues lining the transmembrane helix. Our results suggest that the alteration in the conformational equilibrium of the intracellular K+-gate is one of the fundamental mechanisms underlying the dysfunctions of K+ channels caused by disease-related mutations.


PMID: 33057011 [PubMed - indexed for MEDLINE]



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