Structural highlights
Function
MSCK_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 PubMed
Mechanosensitive 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
- ↑ Levina N, Totemeyer S, Stokes NR, Louis P, Jones MA, Booth IR. Protection of Escherichia coli cells against extreme turgor by activation of MscS and MscL mechanosensitive channels: identification of genes required for MscS activity. EMBO J. 1999 Apr 1;18(7):1730-7. PMID:10202137 doi:http://dx.doi.org/10.1093/emboj/18.7.1730
- ↑ McLaggan D, Jones MA, Gouesbet G, Levina N, Lindey S, Epstein W, Booth IR. Analysis of the kefA2 mutation suggests that KefA is a cation-specific channel involved in osmotic adaptation in Escherichia coli. Mol Microbiol. 2002 Jan;43(2):521-36. doi: 10.1046/j.1365-2958.2002.02764.x. PMID:11985727 doi:http://dx.doi.org/10.1046/j.1365-2958.2002.02764.x
- ↑ Li Y, Moe PC, Chandrasekaran S, Booth IR, Blount P. Ionic regulation of MscK, a mechanosensitive channel from Escherichia coli. EMBO J. 2002 Oct 15;21(20):5323-30. doi: 10.1093/emboj/cdf537. PMID:12374733 doi:http://dx.doi.org/10.1093/emboj/cdf537
- ↑ Mount J, Maksaev G, Summers BT, Fitzpatrick JAJ, Yuan P. Structural basis for mechanotransduction in a potassium-dependent mechanosensitive ion channel. Nat Commun. 2022 Nov 12;13(1):6904. doi: 10.1038/s41467-022-34737-0. PMID:36371466 doi:http://dx.doi.org/10.1038/s41467-022-34737-0
