title: Proteolysis of virulence regulator ToxR is associated with entry of Vibrio cholerae into a dormant state.
abstract: Vibrio cholerae O1 is a natural inhabitant of aquatic environments and causes the diarrheal disease, cholera. Two of its primary virulence regulators, TcpP and ToxR, are localized in the inner membrane. TcpP is encoded on the Vibrio Pathogenicity Island (VPI), a horizontally acquired mobile genetic element, and functions primarily in virulence gene regulation. TcpP has been shown to undergo regulated intramembrane proteolysis (RIP) in response to environmental conditions that are unfavorable for virulence gene expression. ToxR is encoded in the ancestral genome and is present in non-pathogenic strains of V. cholerae, indicating it has roles outside of the human host. In this study, we show that ToxR undergoes RIP in V. cholerae in response to nutrient limitation at alkaline pH, a condition that occurs during the stationary phase of growth. This process involves the site-2 protease RseP (YaeL), and is dependent upon the RpoE-mediated periplasmic stress response, as deletion mutants for the genes encoding these two proteins cannot proteolyze ToxR under nutrient limitation at alkaline pH. We determined that the loss of ToxR, genetically or by proteolysis, is associated with entry of V. cholerae into a dormant state in which the bacterium is normally found in the aquatic environment called viable but nonculturable (VBNC). Strains that can proteolyze ToxR, or do not encode it, lose culturability, experience a change in morphology associated with cells in VBNC, yet remain viable under nutrient limitation at alkaline pH. On the other hand, mutant strains that cannot proteolyze ToxR remain culturable and maintain the morphology of cells in an active state of growth. Overall, our findings provide a link between the proteolysis of a virulence regulator and the entry of a pathogen into an environmentally persistent state.
authors.affiliation: Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America.
authors.forename: Salvador
authors.initials: S
authors.lastname: Almagro-Moreno
authors.affiliation: Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America.
authors.forename: Tae K
authors.initials: TK
authors.lastname: Kim
authors.affiliation: Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America.
authors.forename: Karen
authors.initials: K
authors.lastname: Skorupski
authors.affiliation: Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America.
authors.forename: Ronald K
authors.initials: RK
authors.lastname: Taylor
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002455:Cell Division; D004268:DNA-Binding Proteins / Q000378:metabolism*; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D059748:Proteolysis; D014157:Transcription Factors / Q000378:metabolism*; D014734:Vibrio cholerae / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; C066719:toxR protein, bacteria; D010450:Endopeptidases
references.citation: J Bacteriol. 2001 May;183(9):2746-54
references.pmid: 11292792
references.citation: Microbiology. 2008 Jul;154(Pt 7):1989-97
references.pmid: 18599827
references.citation: Infect Immun. 2007 Dec;75(12):5542-9
references.pmid: 17875629
references.citation: Mol Microbiol. 2007 Feb;63(3):848-58
references.pmid: 17181782
references.citation: Nature. 2002 Jun 6;417(6889):642-5
references.pmid: 12050664
references.citation: J Bacteriol. 2009 Aug;191(16):5044-56
references.pmid: 19542291
references.citation: PLoS One. 2012;7(2):e32523
references.pmid: 22384269
references.citation: Mar Pollut Bull. 2006 Nov;52(11):1425-30
references.pmid: 16764894
references.citation: Appl Environ Microbiol. 1990 Jun;56(6):1977-80
references.pmid: 2383016
references.citation: Mol Microbiol. 2004 Jul;53(1):345-54
references.pmid: 15225327
references.citation: J Infect Dis. 2006 Apr 1;193(7):1029-36
references.pmid: 16518766
references.citation: J Bacteriol. 1994 May;176(10):3085-8
references.pmid: 8188612
references.citation: Mol Microbiol. 2006 Oct;62(2):580-91
references.pmid: 17020588
references.citation: Nature. 2005 Dec 8;438(7069):863-6
references.pmid: 16341015
references.citation: Proc Natl Acad Sci U S A. 2007 Nov 6;104(45):17801-6
references.pmid: 17968017
references.citation: Mol Microbiol. 2003 Mar;47(5):1459-73
references.pmid: 12603748
references.citation: Microb Ecol. 1982 Dec;8(4):313-23
references.pmid: 24226049
references.citation: Mol Microbiol. 2000 Feb;35(4):896-910
references.pmid: 10692166
references.citation: J Bacteriol. 2000 Aug;182(15):4295-303
references.pmid: 10894740
references.citation: Curr Opin Microbiol. 2005 Apr;8(2):122-6
references.pmid: 15802241
references.citation: Microbiol Spectr. 2013 Dec;1(2):null
references.pmid: 26184966
references.citation: Proc Natl Acad Sci U S A. 1996 Jul 23;93(15):7991-5
references.pmid: 8755590
references.citation: Cell Mol Life Sci. 2008 May;65(9):1347-60
references.pmid: 18278577
references.citation: Environ Microbiol. 2006 Apr;8(4):658-66
references.pmid: 16584477
references.citation: Gene. 1996 Feb 22;169(1):47-52
references.pmid: 8635748
references.citation: Curr Opin Microbiol. 1999 Apr;2(2):159-65
references.pmid: 10322173
references.citation: PLoS Pathog. 2006 Oct;2(10):e109
references.pmid: 17054394
references.citation: Front Microbiol. 2013 Dec 16;4:375
references.pmid: 24379807
references.citation: Res Microbiol. 2009 Nov;160(9):696-703
references.pmid: 19778605
references.citation: Cell Host Microbe. 2007 Oct 11;2(4):264-77
references.pmid: 18005744
references.citation: Mol Microbiol. 1995 Aug;17(4):713-26
references.pmid: 8801425
references.citation: Mol Microbiol. 2000 Oct;38(1):67-84
references.pmid: 11029691
references.citation: New Microbiol. 2010 Oct;33(4):359-72
references.pmid: 21213595
references.citation: Nature. 2005 Jul 21;436(7049):406-9
references.pmid: 16034419
references.citation: Mol Microbiol. 2002 Mar;43(6):1577-89
references.pmid: 11952906
references.citation: Infect Immun. 2012 May;80(5):1834-45
references.pmid: 22392925
references.citation: J Appl Microbiol. 2004;96(2):359-66
references.pmid: 14723697
references.citation: J Bacteriol. 1988 Jun;170(6):2575-83
references.pmid: 2836362
references.citation: PLoS Pathog. 2013;9(12):e1003800
references.pmid: 24385900
references.citation: Proc Natl Acad Sci U S A. 1987 May;84(9):2833-7
references.pmid: 2883655
references.citation: Genes Dev. 2002 Aug 15;16(16):2156-68
references.pmid: 12183369
references.citation: Mol Microbiol. 1998 Mar;27(5):977-85
references.pmid: 9535087
references.citation: J Bacteriol. 1998 Sep;180(17):4724-33
references.pmid: 9721317
references.citation: Infect Immun. 2013 Oct;81(10):3935-41
references.pmid: 23918781
references.citation: Proc Natl Acad Sci U S A. 2005 Nov 8;102(45):16403-8
references.pmid: 16254052
references.citation: Environ Microbiol. 2003 Oct;5(10):850-8
references.pmid: 14510838
references.citation: Infect Immun. 2012 Feb;80(2):518-28
references.pmid: 22144480
references.citation: Curr Opin Microbiol. 2008 Dec;11(6):535-40
references.pmid: 18983936
references.citation: Infect Immun. 2005 Aug;73(8):4488-93
references.pmid: 16040959
references.citation: J Bacteriol. 1999 Oct;181(19):5915-21
references.pmid: 10498702
references.citation: Methods Enzymol. 1994;235:386-405
references.pmid: 8057911
references.citation: Microbiology. 1995 Feb;141 ( Pt 2):377-83
references.pmid: 7704268
references.citation: Proc Natl Acad Sci U S A. 1998 Mar 17;95(6):3134-9
references.pmid: 9501228
references.citation: Mol Microbiol. 2004 May;52(3):613-9
references.pmid: 15101969
references.citation: Environ Microbiol. 2007 Feb;9(2):393-402
references.pmid: 17222137
references.citation: Appl Environ Microbiol. 1983 Jan;45(1):275-83
references.pmid: 6337551
references.citation: FEMS Microbiol Rev. 2010 Jul;34(4):415-25
references.pmid: 20059548
references.citation: Infect Immun. 2002 Oct;70(10):5355-62
references.pmid: 12228259
references.citation: PLoS One. 2013;8(1):e53504
references.pmid: 23326443
references.citation: Proc Natl Acad Sci U S A. 1998 Jan 20;95(2):730-4
references.pmid: 9435261
references.citation: Cell. 1987 Jan 30;48(2):271-9
references.pmid: 3802195
references.citation: Appl Environ Microbiol. 2013 Oct;79(19):5970-7
references.pmid: 23872565
references.citation: Arch Microbiol. 1994;162(5):323-8
references.pmid: 7857197
references.citation: Microbiology. 2011 Oct;157(Pt 10):2942-53
references.pmid: 21778208
references.citation: J Appl Microbiol. 2010 Sep;109(3):888-99
references.pmid: 20345385
references.citation: Proc Natl Acad Sci U S A. 2010 Jan 26;107(4):1588-93
references.pmid: 20080633
references.citation: Infect Immun. 2014 Sep;82(9):3667-77
references.pmid: 24935982
references.citation: J Bacteriol. 2000 Jun;182(12):3405-15
references.pmid: 10852871
references.citation: Infect Immun. 1999 May;67(5):2178-83
references.pmid: 10225872
references.citation: Infect Immun. 2008 Sep;76(9):4145-51
references.pmid: 18591230
references.citation: Mol Microbiol. 1997 Sep;25(6):1099-111
references.pmid: 9350866
references.citation: Proc Natl Acad Sci U S A. 2013 Jun 11;110(24):9926-31
references.pmid: 23716683
references.citation: Proc Natl Acad Sci U S A. 2007 Jan 16;104(3):1003-8
references.pmid: 17215357
references.citation: Nat Rev Microbiol. 2009 Jun;7(6):411-23
references.pmid: 19421188
references.citation: Genes Dev. 1999 Sep 15;13(18):2449-61
references.pmid: 10500101
references.citation: Mol Microbiol. 2011 Sep;81(6):1640-53
references.pmid: 21883522
references.citation: Mol Microbiol. 1997 Jan;23(2):323-31
references.pmid: 9044266
references.citation: Proc Natl Acad Sci U S A. 2003 Mar 4;100(5):2801-6
references.pmid: 12601157
references.citation: Genes Dev. 2002 Aug 15;16(16):2147-55
references.pmid: 12183368
references.citation: Proc Natl Acad Sci U S A. 1999 Dec 21;96(26):14765-70
references.pmid: 10611287
references.citation: Cell. 1991 Jan 11;64(1):29-37
references.pmid: 1898871
references.citation: Proc Natl Acad Sci U S A. 2007 May 8;104(19):8107-12
references.pmid: 17470813
references.citation: FEMS Microbiol Lett. 1999 Nov 15;180(2):123-31
references.pmid: 10556702