Ion selectivity of Chlamydomonas MSC1 [mechanosensitive channel 1] expressed in E. coli

Range PK : PCl : PBr : PI = 1: 7 : 9 : 9
Organism Algae Chlamydomonas spp.
Reference Martinac B, Saimi Y, Kung C. Ion channels in microbes. Physiol Rev. 2008 Oct88(4):1449-90. doi: 10.1152/physrev.00005.2008. p.1476 left column 2nd paragraphPubMed ID18923187
Primary Source [238] Martinac B, Buechner M, Delcour AH, Adler J, Kung C. Pressure-sensitive ion channel in Escherichia coli. Proc Natl Acad Sci U S A. 1987 84: 2297–2301. [354] Sotomayor M, Vasquez V, Perozo E, Schulten K. Ion conduction through MscS as determined by electrophysiology and simulation. Biophys J. 2007 92: 886–902. [364] Sukharev S. Purification of the small mechanosensitive channel of Escherichia coli (MscS): the subunit structure, conduction, and gating characteristics in liposomes. Biophys J. 2002 83: 290–298. [368] Sukharev SI, Martinac B, Arshavsky VY, Kung C. Two types of mechanosensitive channels in the E. coli cell envelope: solubilization and functional reconstitution. Biophys J. 1993 65: 177–183.PubMed ID2436228, 17114233, 12080120, 7690260
Comments P.1476 left column 2nd paragraph:"Another mechanosensitive ion channel is MSC1 (ref 266) that is a homolog of prokaryotic MscS. (See Section II.A.4.). MSC1 has 3 putative transmembrane domains and high homology to bacterial MscS can be found in TM3. When expressed in E. coli, it corresponds to a ~400 pS conductance, though its N-terminus signal sequence has to be removed prior to expression. MSC1 is activated by membrane tension but not by membrane potential changes. It requires moderate tension, approximately 80% of tension that activates MscL of E. coli. The channel activity diminishes upon hyperpolarization despite continued membrane tension, whereas the activity is maintained upon depolarization. The channel prefers anions over cations (PK : PCl : P Br : PI = 1: 7 : 9 : 9), whereas E. coli’s MscS is less selective (PCl : PK = 1: 1.5–3.0 (primary sources)). Most astonishing feature of MSC1 expressed in E. coli is its hysteresis behavior depending on how tension is applied to the membrane." P stands for (relative) permeability
Entered by Uri M
ID 112286