title: Contribution of the stg fimbrial operon of Salmonella enterica serovar Typhi during interaction with human cells.
abstract: Salmonella serovars contain a wide variety of putative fimbrial systems that may contribute to colonization of specific niches. Salmonella enterica serovar Typhi is the etiologic agent of typhoid fever and is a pathogen specific to humans. In a previous study, we identified a gene, STY3920 (stgC), encoding the predicted usher of the stg fimbrial operon, that was expressed by serovar Typhi during infection of human macrophages. The stg genes are located in the glmS-pstS intergenic region in serovar Typhi and certain Escherichia coli strains, but they are absent in other S. enterica serovars. We cloned the stg fimbrial operon into a nonfimbriate E. coli K-12 strain and into S. enterica serovar Typhimurium. We demonstrated that the stg fimbrial operon contributed to increased adherence to human epithelial cells. Transcriptional fusion assays with serovar Typhi suggested that stg is preferentially expressed in minimal medium. Deletion of stg reduced adherence of serovar Typhi to epithelial cells. However, deletion of stg increased uptake of serovar Typhi by human macrophages, and overexpression of stg in serovar Typhi and serovar Typhimurium strains reduced phagocytosis by human macrophages. These strains survived inside macrophages as well as the wild-type parent. Although the stgC gene contains a premature stop codon that disrupts the expected open reading frame encoding the usher and is therefore considered a pseudogene, our results show that the stg operon may encode a functional fimbria. Thus, this serovar Typhi-specific fimbrial operon contributes to interactions with host cells, and further characterization is important for understanding the role of the stg fimbrial cluster in typhoid fever pathogenesis.
authors: Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montréal, Québec, Canada H3C 3J7.
authors: Chantal
authors: C
authors: Forest
authors: Sébastien P
authors: SP
authors: Faucher
authors: Katherine
authors: K
authors: Poirier
authors: Sébastien
authors: S
authors: Houle
authors: Charles M
authors: CM
authors: Dozois
authors: France
authors: F
authors: Daigle
mesh_terms: D019677:Artificial Gene Fusion; D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D003001:Cloning, Molecular; D004847:Epithelial Cells / Q000382:microbiology*; D048168:Escherichia coli K12 / Q000235:genetics / Q000502:physiology; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D050296:Microbial Viability; D009876:Operon; D010587:Phagocytosis; D012485:Salmonella typhi / Q000235:genetics / Q000502:physiology*; D012486:Salmonella typhimurium / Q000235:genetics / Q000502:physiology
references: Infect Immun. 1987 Dec;55(12):2891-901
references: 3316027
references: Infect Immun. 1990 Jun;58(6):1879-85
references: 2160435
references: Gene. 1996 Dec 12;183(1-2):207-13
references: 8996108
references: Res Microbiol. 2006 Mar;157(2):153-61
references: 16125910
references: FEMS Microbiol Rev. 1996 Oct;19(1):25-52
references: 8916554
references: Nature. 2001 Oct 25;413(6858):848-52
references: 11677608
references: Res Microbiol. 1993 Sep;144(7):507-27
references: 7906046
references: Infect Immun. 1998 Dec;66(12):5599-606
references: 9826331
references: Mol Microbiol. 2001 Sep;41(5):1211-22
references: 11555299
references: Infect Immun. 2005 Jun;73(6):3367-74
references: 15908363
references: FEMS Microbiol Lett. 2004 Sep 15;238(2):333-44
references: 15358418
references: Infect Immun. 2004 Mar;72(3):1230-9
references: 14977923
references: Infect Immun. 2002 Dec;70(12):6761-9
references: 12438351
references: J Bacteriol. 1993 May;175(9):2770-8
references: 8097517
references: J Bacteriol. 2006 Sep;188(18):6449-59
references: 16952934
references: J Bacteriol. 2003 Apr;185(7):2330-7
references: 12644504
references: J Bacteriol. 2004 May;186(10):3214-23
references: 15126484
references: Microbes Infect. 2006 Jun;8(7):1741-9
references: 16815722
references: Nature. 2001 Oct 25;413(6858):852-6
references: 11677609
references: Infect Immun. 2006 Apr;74(4):2233-44
references: 16552054
references: Infect Immun. 2004 Oct;72(10):6168-71
references: 15385526
references: Infect Immun. 2002 Oct;70(10):5416-27
references: 12228266
references: Antimicrob Agents Chemother. 2005 Oct;49(10):4052-60
references: 16189080
references: Infect Immun. 2005 Aug;73(8):5217-21
references: 16041043
references: Infect Immun. 2000 Jun;68(6):3067-73
references: 10816445
references: Mol Microbiol. 2003 Jun;48(5):1357-76
references: 12787362
references: Proc Natl Acad Sci U S A. 2004 Dec 14;101(50):17492-7
references: 15576509
references: Mol Microbiol. 1996 Nov;22(4):703-14
references: 8951817
references: Infect Immun. 2005 Sep;73(9):5329-38
references: 16113248
references: J Bacteriol. 2004 Sep;186(17):5883-98
references: 15317794
references: Infect Immun. 2006 Sep;74(9):5161-8
references: 16926408
references: Lancet. 1987 Nov 21;2(8569):1165-9
references: 2890805
references: Methods Enzymol. 1994;236:282-306
references: 7968616
references: Mol Gen Genet. 1990 Aug;223(1):156-8
references: 2259337
references: FEMS Immunol Med Microbiol. 1996 Dec 1;16(2):127-39
references: 8988393
references: Infect Immun. 2006 Jan;74(1):265-72
references: 16368980
references: Gene. 1991 Apr;100:195-9
references: 2055470
references: Infect Immun. 2001 May;69(5):2894-901
references: 11292704
references: Gene. 1991 Dec 20;109(1):137-41
references: 1756974
references: Methods Enzymol. 1994;236:467-76
references: 7968631