7uw5
From Proteopedia
EcMscK G924S mutant in a closed conformation
Structural highlights
FunctionMSCK_ECOLI Mechanosensitive channel that opens in response to membrane tension and specific ionic conditions. Requires high concentrations of external K(+), NH(4)(+), Rb(+) or Cs(+) to gate. May participate in the regulation of osmotic pressure changes within the cell, although it does not appear to have a major role in osmolarity regulation. Forms an ion channel of 1.0 nanosiemens conductance. The channel can remain active for between 30 seconds and over 3 minutes; it does not desensitize upon extended pressure. Its activity is masked in wild-type cells by the MscS channel.[1] [2] [3] Publication Abstract from PubMedMechanosensitive channels of small conductance, found in many living organisms, open under elevated membrane tension and thus play crucial roles in biological response to mechanical stress. Amongst these channels, MscK is unique in that its activation also requires external potassium ions. To better understand this dual gating mechanism by force and ligand, we elucidate distinct structures of MscK along the gating cycle using cryo-electron microscopy. The heptameric channel comprises three layers: a cytoplasmic domain, a periplasmic gating ring, and a markedly curved transmembrane domain that flattens and expands upon channel opening, which is accompanied by dilation of the periplasmic ring. Furthermore, our results support a potentially unifying mechanotransduction mechanism in ion channels depicted as flattening and expansion of the transmembrane domain. Structural basis for mechanotransduction in a potassium-dependent mechanosensitive ion channel.,Mount J, Maksaev G, Summers BT, Fitzpatrick JAJ, Yuan P Nat Commun. 2022 Nov 12;13(1):6904. doi: 10.1038/s41467-022-34737-0. PMID:36371466[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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