title: Electrophysiological characterization of the mechanosensitive channel MscCG in Corynebacterium glutamicum.
abstract: Corynebacterium glutamicum MscCG, also referred to as NCgl1221, exports glutamate when biotin is limited in the culture medium. MscCG is a homolog of Escherichia coli MscS, which serves as an osmotic safety valve in E. coli cells. Patch-clamp experiments using heterogeneously expressed MscCG have shown that MscCG is a mechanosensitive channel gated by membrane stretch. Although the association of glutamate secretion with the mechanosensitive gating has been suggested, the electrophysiological characteristics of MscCG have not been well established. In this study, we analyzed the mechanosensitive gating properties of MscCG by expressing it in E. coli spheroplasts. MscCG is permeable to glutamate, but is also permeable to chloride and potassium. The tension at the midpoint of activation is 6.68 ± 0.63 mN/m, which is close to that of MscS. The opening rates at saturating tensions and closing rates at zero tension were at least one order of magnitude slower than those observed for MscS. This slow kinetics produced strong opening-closing hysteresis in response to triangular pressure ramps. Whereas MscS is inactivated under sustained stimulus, MscCG does not undergo inactivation. These results suggest that the mechanosensitive gating properties of MscCG are not suitable for the response to abrupt and harmful changes, such as osmotic downshock, but are tuned to execute slower processes, such as glutamate export.
authors.affiliation: Department of Biology, Tokyo Gakugei University, Tokyo, Japan. Electronic address: y_nakayama9339@nifty.com.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nakayama
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Yoshimura
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Iida
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D055724:Electrophysiological Phenomena; D007473:Ion Channels / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation
chemical_list: D001426:Bacterial Proteins; D007473:Ion Channels
references.citation: Biochemistry. 2011 May 17;50(19):4087-96
references.pmid: 21456519
references.citation: Biochim Biophys Acta. 2013 Apr;1828(4):1230-40
references.pmid: 23313454
references.citation: J Gen Physiol. 2011 Jul;138(1):49-57
references.pmid: 21670207
references.citation: Physiol Behav. 1992 Nov;52(5):879-84
references.pmid: 1484843
references.citation: Nat Struct Mol Biol. 2007 Dec;14(12):1141-9
references.pmid: 18037888
references.citation: J Gen Physiol. 1999 Apr;113(4):525-40
references.pmid: 10102934
references.citation: Biosci Biotechnol Biochem. 2006 Jan;70(1):22-30
references.pmid: 16428817
references.citation: EMBO J. 2002 Oct 15;21(20):5323-30
references.pmid: 12374733
references.citation: Appl Environ Microbiol. 2012 Aug;78(15):5432-4
references.pmid: 22610427
references.citation: Biosci Biotechnol Biochem. 2010;74(12):2546-9
references.pmid: 21150093
references.citation: Proc Natl Acad Sci U S A. 1987 Apr;84(8):2297-301
references.pmid: 2436228
references.citation: Proc Natl Acad Sci U S A. 2010 Jul 13;107(28):12664-9
references.pmid: 20616037
references.citation: J Gen Physiol. 2005 Feb;125(2):143-54
references.pmid: 15657299
references.citation: Appl Environ Microbiol. 2007 Jul;73(14):4491-8
references.pmid: 17513583
references.citation: Biophys J. 2009 Aug 19;97(4):1048-57
references.pmid: 19686652
references.citation: Nat Struct Mol Biol. 2005 Feb;12(2):113-9
references.pmid: 15665866
references.citation: J Gen Physiol. 2005 Feb;125(2):155-70
references.pmid: 15684093
references.citation: Proc Natl Acad Sci U S A. 2012 Nov 13;109(46):19015-20
references.pmid: 23112188
references.citation: J Gen Physiol. 2010 Jun;135(6):641-52
references.pmid: 20513760
references.citation: Biophys J. 2008 Mar 1;94(5):1638-45
references.pmid: 17993482
references.citation: PLoS One. 2012;7(3):e33077
references.pmid: 22427953
references.citation: FEMS Microbiol Lett. 2003 Jan 28;218(2):305-9
references.pmid: 12586408
references.citation: Pflugers Arch. 2002 Oct;445(1):161-6
references.pmid: 12397401
references.citation: Eur Biophys J. 2009 Sep;38(7):1013-27
references.pmid: 19424690
references.citation: Channels (Austin). 2012 Jul-Aug;6(4):272-81
references.pmid: 22874652
references.citation: Biosci Biotechnol Biochem. 2012;76(7):1422-4
references.pmid: 22785475
references.citation: EMBO J. 1999 Apr 1;18(7):1730-7
references.pmid: 10202137
references.citation: Biophys J. 2013 Apr 2;104(7):1426-34
references.pmid: 23561519
references.citation: Biophys J. 2002 Jul;83(1):290-8
references.pmid: 12080120
references.citation: Chembiochem. 2012 Sep 24;13(14):2037-43
references.pmid: 22915507
references.citation: J Membr Biol. 1996 May;151(2):175-87
references.pmid: 8661505
references.citation: J Biotechnol. 2003 Sep 4;104(1-3):155-72
references.pmid: 12948636
references.citation: Proc Natl Acad Sci U S A. 2007 Apr 3;104(14):5883-8
references.pmid: 17389370
references.citation: J Biochem. 1962 Jan;51:56-62
references.pmid: 13911888
references.citation: Eur J Biochem. 1997 Jul 15;247(2):572-80
references.pmid: 9266699
references.citation: Biophys J. 2006 Oct 15;91(8):2874-81
references.pmid: 16861270
references.citation: Proc Natl Acad Sci U S A. 2012 May 29;109(22):8770-5
references.pmid: 22586095
references.citation: Science. 2002 Nov 22;298(5598):1582-7
references.pmid: 12446901
references.citation: Biophys J. 2010 Nov 3;99(9):2870-8
references.pmid: 21044584
references.citation: Appl Microbiol Biotechnol. 2011 Jul;91(1):143-51
references.pmid: 21503757
references.citation: Biochim Biophys Acta. 2010 Nov;1798(11):2141-9
references.pmid: 20599688