Contribution of the stg fimbrial operon of Salmonella enterica serovar Typhi during interaction with human cells.
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.
Forest
Chantal
C
Department of Microbiology and Immunology, University of Montreal, C.P. 6128 Succursale Centre-Ville, Montréal, Québec, Canada H3C 3J7.
Faucher
Sébastien P
SP
Poirier
Katherine
K
Houle
Sébastien
S
Dozois
Charles M
CM
Daigle
France
F
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
Infect Immun. 1987 Dec;55(12):2891-901
3316027
Infect Immun. 1990 Jun;58(6):1879-85
2160435
Gene. 1996 Dec 12;183(1-2):207-13
8996108
Res Microbiol. 2006 Mar;157(2):153-61
16125910
FEMS Microbiol Rev. 1996 Oct;19(1):25-52
8916554
Nature. 2001 Oct 25;413(6858):848-52
11677608
Res Microbiol. 1993 Sep;144(7):507-27
7906046
Infect Immun. 1998 Dec;66(12):5599-606
9826331
Mol Microbiol. 2001 Sep;41(5):1211-22
11555299
Infect Immun. 2005 Jun;73(6):3367-74
15908363
FEMS Microbiol Lett. 2004 Sep 15;238(2):333-44
15358418
Infect Immun. 2004 Mar;72(3):1230-9
14977923
Infect Immun. 2002 Dec;70(12):6761-9
12438351
J Bacteriol. 1993 May;175(9):2770-8
8097517
J Bacteriol. 2006 Sep;188(18):6449-59
16952934
J Bacteriol. 2003 Apr;185(7):2330-7
12644504
J Bacteriol. 2004 May;186(10):3214-23
15126484
Microbes Infect. 2006 Jun;8(7):1741-9
16815722
Nature. 2001 Oct 25;413(6858):852-6
11677609
Infect Immun. 2006 Apr;74(4):2233-44
16552054
Infect Immun. 2004 Oct;72(10):6168-71
15385526
Infect Immun. 2002 Oct;70(10):5416-27
12228266
Antimicrob Agents Chemother. 2005 Oct;49(10):4052-60
16189080
Infect Immun. 2005 Aug;73(8):5217-21
16041043
Infect Immun. 2000 Jun;68(6):3067-73
10816445
Mol Microbiol. 2003 Jun;48(5):1357-76
12787362
Proc Natl Acad Sci U S A. 2004 Dec 14;101(50):17492-7
15576509
Mol Microbiol. 1996 Nov;22(4):703-14
8951817
Infect Immun. 2005 Sep;73(9):5329-38
16113248
J Bacteriol. 2004 Sep;186(17):5883-98
15317794
Infect Immun. 2006 Sep;74(9):5161-8
16926408
Lancet. 1987 Nov 21;2(8569):1165-9
2890805
Methods Enzymol. 1994;236:282-306
7968616
Mol Gen Genet. 1990 Aug;223(1):156-8
2259337
FEMS Immunol Med Microbiol. 1996 Dec 1;16(2):127-39
8988393
Infect Immun. 2006 Jan;74(1):265-72
16368980
Gene. 1991 Apr;100:195-9
2055470
Infect Immun. 2001 May;69(5):2894-901
11292704
Gene. 1991 Dec 20;109(1):137-41
1756974
Methods Enzymol. 1994;236:467-76
7968631