title: Pathoadaptive conditional regulation of the type VI secretion system in Vibrio cholerae O1 strains.
abstract: The most recently discovered secretion pathway in gram-negative bacteria, the type VI secretion system (T6SS), is present in many species and is considered important for the survival of non-O1 non-O139 Vibrio cholerae in aquatic environments. Until now, it was not known whether there is a functionally active T6SS in wild-type V. cholerae O1 strains, the cause of cholera disease in humans. Here, we demonstrate the presence of a functionally active T6SS in wild-type V. cholerae O1 strains, as evidenced by the secretion of the T6SS substrate Hcp, which required several gene products encoded within the putative vas gene cluster. Our analyses showed that the T6SS of wild-type V. cholerae O1 strain A1552 was functionally activated when the bacteria were grown under high-osmolarity conditions. The T6SS was also active when the bacteria were grown under low temperature (23°C), suggesting that the system may be important for the survival of the bacterium in the environment. A test of the interbacterial virulence of V. cholerae strain A1552 against an Escherichia coli K-12 strain showed that it was strongly enhanced under high osmolarity and that it depended on the hcp genes. Interestingly, we found that the newly recognized osmoregulatory protein OscR plays a role in the regulation of T6SS gene expression and secretion of Hcp from V. cholerae O1 strains.
authors.affiliation: Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Dharmesh
authors.initials: D
authors.lastname: Sabharwal
authors.forename: Jeanette
authors.initials: J
authors.lastname: Bröms
authors.forename: Debra L
authors.initials: DL
authors.lastname: Milton
authors.forename: Anders
authors.initials: A
authors.lastname: Sjöstedt
authors.forename: Bernt Eric
authors.initials: BE
authors.lastname: Uhlin
authors.forename: Sun Nyunt
authors.initials: SN
authors.lastname: Wai
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001431:Bacteriological Techniques; D004777:Environment; D048168:Escherichia coli K12; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D009994:Osmolar Concentration; D010957:Plasmids; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055571:Secretory Pathway / Q000502:physiology*; D013696:Temperature; D014734:Vibrio cholerae / Q000145:classification* / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence
chemical_list: D001426:Bacterial Proteins
references.citation: PLoS One. 2008 Aug 13;3(8):e2955
references.pmid: 18698408
references.citation: Appl Environ Microbiol. 1982 Nov;44(5):1047-58
references.pmid: 6295276
references.citation: Johns Hopkins Med J. 1972 Dec;131(6):403-11
references.pmid: 4564589
references.citation: Microbiol Immunol. 2004;48(11):791-805
references.pmid: 15557737
references.citation: J Bacteriol. 2005 Mar;187(6):2038-49
references.pmid: 15743952
references.citation: Int J Med Microbiol. 2010 Dec;300(8):534-43
references.pmid: 20947426
references.citation: Gene. 1977;2(2):95-113
references.pmid: 344137
references.citation: Ecohealth. 2009 Sep;6(3):378-89
references.pmid: 20145974
references.citation: Biochim Biophys Acta. 1999 Feb 16;1444(2):269-75
references.pmid: 10023081
references.citation: Proc Natl Acad Sci U S A. 1979 Sep;76(9):4350-4
references.pmid: 388439
references.citation: Proc Natl Acad Sci U S A. 2010 Dec 7;107(49):21128-33
references.pmid: 21084635
references.citation: Science. 1977 Oct 28;198(4315):394-6
references.pmid: 910135
references.citation: Appl Environ Microbiol. 2007 Dec;73(24):7926-33
references.pmid: 17951440
references.citation: PLoS One. 2009 Aug 24;4(8):e6734
references.pmid: 19701456
references.citation: Microb Pathog. 2009 Nov;47(5):243-51
references.pmid: 19716410
references.citation: Nat Cell Biol. 2007 Jul;9(7):797-803
references.pmid: 17558395
references.citation: Science. 2006 Jun 9;312(5779):1526-30
references.pmid: 16763151
references.citation: J Bacteriol. 1998 Feb;180(4):773-84
references.pmid: 9473029
references.citation: Nature. 1970 Aug 15;227(5259):680-5
references.pmid: 5432063
references.citation: Proc Natl Acad Sci U S A. 2006 Jun 13;103(24):9280-5
references.pmid: 16754867
references.citation: Gene. 1986;48(1):119-31
references.pmid: 3549457
references.citation: Microbiol Immunol. 2002;46(2):59-66
references.pmid: 11939579
references.citation: J Bacteriol. 1989 Mar;171(3):1288-93
references.pmid: 2646275
references.citation: Trends Microbiol. 2010 Dec;18(12):531-7
references.pmid: 20961764
references.citation: Lancet. 2004 Jan 17;363(9404):223-33
references.pmid: 14738797
references.citation: Microbes Infect. 2003 Apr;5(4):329-44
references.pmid: 12706446
references.citation: Mol Microbiol. 2008 Oct;70(1):100-11
references.pmid: 18681937
references.citation: Infect Immun. 2002 Oct;70(10):5759-69
references.pmid: 12228306
references.citation: Cell. 1987 Jan 30;48(2):271-9
references.pmid: 3802195
references.citation: J Mol Biol. 1983 Jun 5;166(4):557-80
references.pmid: 6345791
references.citation: Proc Natl Acad Sci U S A. 2007 Sep 25;104(39):15508-13
references.pmid: 17873062
references.citation: J Appl Bacteriol. 1988 Feb;64(2):141-4
references.pmid: 3372399
references.citation: Proc Natl Acad Sci U S A. 2006 Jan 31;103(5):1528-33
references.pmid: 16432199
references.citation: J Biol Chem. 2011 Apr 8;286(14):12317-27
references.pmid: 21325275
references.citation: J Bacteriol. 2006 Apr;188(7):2721-5
references.pmid: 16547062
references.citation: J Mol Biol. 1976 Jul 5;104(3):541-55
references.pmid: 781293
references.citation: In Silico Biol. 2003;3(3):287-300
references.pmid: 12954091
references.citation: J Bacteriol. 2004 Sep;186(18):6298-305
references.pmid: 15342600
references.citation: Clin Microbiol Rev. 1995 Jan;8(1):48-86
references.pmid: 7704895
references.citation: Infect Immun. 1991 Dec;59(12):4310-7
references.pmid: 1937792
references.citation: J Bacteriol. 2009 Jul;191(13):4082-96
references.pmid: 19329635
references.citation: Microbiology (Reading). 2009 Feb;155(Pt 2):498-512
references.pmid: 19202098
references.citation: J Bacteriol. 1988 Jun;170(6):2575-83
references.pmid: 2836362
references.citation: Curr Opin Microbiol. 2008 Feb;11(1):3-8
references.pmid: 18289922
references.citation: PLoS Pathog. 2010 Aug 26;6(8):e1001068
references.pmid: 20865170
references.citation: FEMS Microbiol Rev. 2002 Jun;26(2):125-39
references.pmid: 12069878
references.citation: Cell Host Microbe. 2010 Jan 21;7(1):25-37
references.pmid: 20114026
references.citation: Mol Microbiol. 1996 Jun;20(5):911-7
references.pmid: 8809744
references.citation: Infect Immun. 2009 Mar;77(3):935-42
references.pmid: 19103773
references.citation: Adv Exp Med Biol. 2007;603:211-6
references.pmid: 17966417
references.citation: J Bacteriol. 2010 Aug;192(15):3850-60
references.pmid: 20511495
references.citation: Mol Microbiol. 2006 Jan;59(1):99-112
references.pmid: 16359321
references.citation: J Bacteriol. 1995 Jul;177(14):4121-30
references.pmid: 7608087
references.citation: Microbiology (Reading). 2008 Jun;154(Pt 6):1570-1583
references.pmid: 18524912
references.citation: Proc Natl Acad Sci U S A. 2010 Nov 9;107(45):19520-4
references.pmid: 20974937
references.citation: J Bacteriol. 2004 Jul;186(13):4056-66
references.pmid: 15205407
references.citation: FEMS Microbiol Rev. 2006 Mar;30(2):157-86
references.pmid: 16472303