title: Hha controls Escherichia coli O157:H7 biofilm formation by differential regulation of global transcriptional regulators FlhDC and CsgD.
abstract: Although molecular mechanisms promoting adherence of enterohemorrhagic Escherichia coli (EHEC) O157:H7 on epithelial cells are well characterized, regulatory mechanisms controlling biofilm formation are not fully understood. In this study, we demonstrate that biofilm formation in EHEC O157:H7 strain 86-24 is highly repressed compared to that in an isogenic hha mutant. The hha mutant produced large quantities of biofilm compared to the wild-type strain at 30°C and 37°C. Complementation of the hha mutant reduced the level of biofilm formation to that of the wild-type strain, indicating that Hha is a negative regulator of biofilm production. While swimming motility and expression of the flagellar gene fliC were significantly reduced, the expression of csgA (encoding curlin of curli fimbriae) and the ability to bind Congo red were significantly enhanced. The expression of both fliC and csgA and the phenotypes of motility and curli production affected by these two genes, respectively, were restored to wild-type levels in the complemented hha mutant. The csgA deletion abolished biofilm formation in the hha mutant and wild-type strain, and csgA complementation restored biofilm formation to these strains, indicating the importance of csgA and curli in biofilm formation. The regulatory effects of Hha on flagellar and curli gene expression appear to occur via the induction and repression of FlhDC and CsgD, as demonstrated by reduced flhD and increased csgD transcription in the hha mutant, respectively. In gel shift assays Hha interacted with flhDC and csgD promoters. In conclusion, Hha regulates biofilm formation in EHEC O157:H7 by differential regulation of FlhDC and CsgD, the global regulators of motility and curli production, respectively.
authors: Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, ARS-USDA, Ames, Iowa, USA. vijay.sharma@ars.usda.gov
authors: Vijay K
authors: VK
authors: Sharma
authors: Bradley L
authors: BL
authors: Bearson
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis; D018441:Biofilms / Q000254:growth & development*; D003223:Congo; D003224:Congo Red / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D019453:Escherichia coli O157 / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D008124:Locomotion; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013194:Staining and Labeling; D015534:Trans-Activators / Q000096:biosynthesis*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C499694:CsgD protein, E coli; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D015534:Trans-Activators; C090552:flhC protein, E coli; C090553:flhD protein, E coli; C079209:hha protein, E coli; C077481:Crl protein, Bacteria; D003224:Congo Red
references: Curr Opin Microbiol. 2007 Feb;10(1):17-23
references: 17208514
references: Mol Microbiol. 2002 Jul;45(2):521-32
references: 12123461
references: Environ Microbiol. 2007 Feb;9(2):332-46
references: 17222132
references: Mol Microbiol. 1995 Nov;18(4):661-70
references: 8817489
references: Infect Immun. 1996 Jul;64(7):2881-4
references: 8698530
references: J Bacteriol. 2005 Mar;187(6):2038-49
references: 15743952
references: Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6640-5
references: 10829079
references: J Bacteriol. 1994 Dec;176(23):7345-51
references: 7961507
references: Mol Microbiol. 2001 Jul;41(2):349-63
references: 11489123
references: J Vet Sci. 2004 Jun;5(2):119-24
references: 15192338
references: Annu Rev Microbiol. 1995;49:711-45
references: 8561477
references: Int J Food Microbiol. 1998 Jun 30;42(1-2):9-27
references: 9706794
references: Microbes Infect. 2000 Feb;2(2):157-66
references: 10742688
references: Microbes Infect. 2008 Jun;10(7):807-16
references: 18554972
references: Genes Dev. 2008 Sep 1;22(17):2434-46
references: 18765794
references: Microbiology (Reading). 2008 Jan;154(Pt 1):148-166
references: 18174134
references: Res Microbiol. 2011 Feb-Mar;162(2):108-16
references: 21145393
references: Ann Intern Med. 1988 Nov 1;109(9):705-12
references: 3056169
references: FEMS Microbiol Lett. 1999 Jun 15;175(2):247-53
references: 10386375
references: Infect Agents Dis. 1993 Aug;2(4):272-4
references: 8173808
references: Annu Rev Microbiol. 2006;60:131-47
references: 16704339
references: Curr Opin Microbiol. 1999 Apr;2(2):148-52
references: 10322169
references: J Ind Microbiol. 1995 Sep;15(3):214-26
references: 8519480
references: J Bacteriol. 2004 Nov;186(21):7290-301
references: 15489441
references: J Mol Biol. 2006 Jan 27;355(4):798-808
references: 16337229
references: Appl Environ Microbiol. 2006 Apr;72(4):2564-72
references: 16597958
references: Infect Immun. 1997 Dec;65(12):5320-5
references: 9393832
references: J Mol Microbiol Biotechnol. 2002 May;4(3):341-6
references: 11931567
references: Infect Immun. 1999 Aug;67(8):4260-3
references: 10417201
references: Science. 1998 Apr 10;280(5361):295-8
references: 9535661
references: Clin Microbiol Rev. 1998 Jan;11(1):142-201
references: 9457432
references: Appl Microbiol Biotechnol. 2004 May;64(4):515-24
references: 14727089
references: J Bacteriol. 2007 Aug;189(15):5429-40
references: 17526711
references: J Bacteriol. 2009 Jun;191(11):3451-61
references: 19218393
references: Mol Microbiol. 2006 Nov;62(4):1014-34
references: 17010156
references: Annu Rev Microbiol. 2000;54:49-79
references: 11018124
references: J Bacteriol. 2004 May;186(9):2724-34
references: 15090514
references: Gene. 1995 May 26;158(1):9-14
references: 7789817
references: J Infect Dis. 2000 Feb;181(2):602-12
references: 10669344
references: Nature. 1989 Apr 20;338(6217):652-5
references: 2649795
references: Mol Microbiol. 2001 Sep;41(5):983-97
references: 11555281
references: Jpn J Med Sci Biol. 1998;51 Suppl:S108-14
references: 10211443
references: Microbiol Immunol. 2005;49(9):875-84
references: 16172544
references: Int J Med Microbiol. 2007 Jun;297(3):177-85
references: 17353147
references: Biotechnol Bioeng. 2006 Jan 5;93(1):188-200
references: 16317765
references: Mol Microbiol. 1992 Sep;6(17):2443-52
references: 1357528
references: Mol Microbiol. 1991 May;5(5):1285-93
references: 1956303
references: J Bacteriol. 2007 Oct;189(20):7426-35
references: 17693516
references: Biotechnol Prog. 2005 May-Jun;21(3):689-99
references: 15932244
references: Infect Immun. 2008 Dec;76(12):5598-607
references: 18852247
references: Proc Natl Acad Sci U S A. 1996 Jun 25;93(13):6562-6
references: 8692856
references: FEMS Microbiol Lett. 2005 Feb 1;243(1):189-96
references: 15668018
references: Appl Environ Microbiol. 2001 May;67(5):2367-70
references: 11319125
references: Mol Biotechnol. 2004 Feb;26(2):117-22
references: 14764937
references: J Mol Biol. 2002 Aug 9;321(2):185-99
references: 12144778
references: Infect Immun. 1998 Mar;66(3):944-9
references: 9488380
references: J Bacteriol. 2007 Nov;189(22):8034-43
references: 17873038
references: Nucleic Acids Res. 2007;35(13):4441-52
references: 17576668
references: Mol Microbiol. 1998 Oct;30(2):285-93
references: 9791174
references: Microbiology (Reading). 2010 Aug;156(Pt 8):2470-2483
references: 20466769
references: Mol Microbiol. 2004 Feb;51(3):659-74
references: 14731270
references: PLoS One. 2008 Jun 11;3(6):e2394
references: 18545668
references: Environ Microbiol. 2009 Apr;11(4):992-1006
references: 19187284
references: J Bacteriol. 2006 Jul;188(14):5212-9
references: 16816193
references: Microbiol Mol Biol Rev. 2000 Dec;64(4):694-708
references: 11104815
references: Proc Natl Acad Sci U S A. 2002 Feb 19;99(4):2287-92
references: 11830644
references: J Bacteriol. 2001 Nov;183(22):6620-9
references: 11673432
references: Mol Microbiol. 2003 May;48(4):933-46
references: 12753187
references: J Bacteriol. 2006 Jun;188(11):3731-9
references: 16707665
references: Appl Environ Microbiol. 2005 Dec;71(12):8008-15
references: 16332780
references: J Bacteriol. 1993 Oct;175(19):6238-44
references: 8407796
references: Microbiology (Reading). 2001 Jan;147(Pt 1):145-52
references: 11160808
references: Can J Microbiol. 2003 Jul;49(7):443-9
references: 14569285
references: Infect Immun. 2002 Jan;70(1):395-9
references: 11748206
references: Microbiology (Reading). 2010 May;156(Pt 5):1303-1312
references: 20110300
references: FEMS Microbiol Lett. 1999 Sep 1;178(1):169-75
references: 10483736