Analysis of fimbrial gene clusters and their expression in enterohaemorrhagic <i>Escherichia coli</i> O157:H7

Low, Alison S.; Holden, Nicola; Rosser, Tracy; Roe, Andrew J.; Constantinidou, Chrystala; Hobman, Jon L.; Smith, David George Emslie; Low, J. C.; Gally, David L.

doi:10.1111/j.1462-2920.2006.00995.x

Cited by 98 publications

(140 citation statements)

References 56 publications

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“…It is likely that in some E. coli strains, hcpA gene expression, like that of many other virulence factors, requires specific growth conditions that trigger or repress regulatory elements that lead to successful gene expression. So far, the HCP has been observed only in E. coli O157:H7, and other studies have indicated that hcpA is a cryptic gene in laboratory and pathogenic strains (14,26,49). While the hcpA gene is widely distributed among E. coli strains, it remains unknown what E. coli pathogroups apart from EHEC assemble HCP.…”

Section: Discussionmentioning

confidence: 99%

Fimbrial Adhesins Produced by Atypical Enteropathogenic Escherichia coli Strains

Hernandes

Velsko

Sampaio³

et al. 2011

Appl Environ Microbiol

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Atypical enteropathogenic Escherichia coli (aEPEC) has emerged as a significant cause of pediatric diarrhea worldwide; however, information regarding its adherence mechanisms to the human gut mucosa is lacking. In this study, we investigated the prevalence of several (fimA, ecpA, csgA, elfA, and hcpA) fimbrial genes in 71 aEPEC strains isolated from children with diarrhea (54 strains) and healthy individuals (17 strains) in Brazil and Australia by PCR. These genes are associated with adhesion and/or biofilm formation of pathogenic and commensal E. coli. Here, the most prevalent fimbrial genes found, in descending order, were hcpA (98.6%), ecpA (86%), fimA (76%), elfA (72%), and csgA (19.7%). Phenotypic expression of pili in aEPEC strains was assessed by several approaches. We were not able to detect the hemorrhagic coli pilus (HCP) or the E. coli lamininbinding fimbriae (ELF) in these strains by using immunofluorescence. Type 1 pili and curli were detected in 59% (by yeast agglutination) and 2.8% (by Congo red binding and immunofluorescence) of the strains, respectively. The E. coli common pilus (ECP) was evidenced in 36.6% of the strains on bacteria adhering to HeLa cells by immunofluorescence, suggesting that ECP could play an important role in cell adherence for some aEPEC strains. This study highlights the complex nature of the adherence mechanisms of aEPEC strains involving the coordinated function of fimbrial (e.g., ECP) and nonfimbrial (e.g., intimin) adhesins and indicates that these strains bear several pilus operons that could potentially be expressed in different niches favoring colonization and survival in and outside the host.

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Section: Discussionmentioning

confidence: 99%

Fimbrial Adhesins Produced by Atypical Enteropathogenic Escherichia coli Strains

Hernandes

Velsko

Sampaio³

et al. 2011

Appl Environ Microbiol

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“…Except for genes encoding curli (csgA), a fimA-like gene, and ybgD and yehD (putative pilin genes), the expression of the remaining 12 pilin subunit genes, including ecpA, was not demonstrated under the conditions examined (32). Likewise, genome-wide-scale efforts using transposon or signature-tagged mutagenesis have not evidenced a role for ECP in adherence to Caco-2 cells or in colonization of the bovine gastrointestinal tract (36,37).…”

Section: Discussionmentioning

confidence: 99%

“…The expression of the 16 putative pili operons present in EHEC O157:H7 was previously investigated through transcriptional analysis (32). Except for genes encoding curli (csgA), a fimA-like gene, and ybgD and yehD (putative pilin genes), the expression of the remaining 12 pilin subunit genes, including ecpA, was not demonstrated under the conditions examined (32).…”

Section: Discussionmentioning

confidence: 99%

“…Other less well characterized surface adhesins have been reported (27)(28)(29)(30)(31), but their role in in vivo adherence and host colonization remains elusive. The genome of EHEC O157:H7 strains contains 16 loci-encoding genes putatively involved in pili biosynthesis (6,8,32); however, what role they play in the pathogenic scheme of these organisms remains largely unknown. In this article, we demonstrate the production of a pilus in EHEC, other E. coli pathogroups, and NFEC isolates that we hypothesize is involved in promoting bacterial adherence and host colonization.…”

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confidence: 99%

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Commensal and pathogenic Escherichia coli use a common pilus adherence factor for epithelial cell colonization

Rendón

Saldaña

Erdem

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

256

302

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Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a food-borne pathogen that causes hemorrhagic colitis and the hemolytic uremic syndrome. Colonization of the human gut mucosa and production of potent Shiga toxins are critical virulence traits of EHEC. Although EHEC O157:H7 contains numerous putative pili operons, their role in the colonization of the natural bovine or accidental human hosts remains largely unknown. We have identified in EHEC an adherence factor, herein called E. coli common pilus (ECP), composed of a 21-kDa pilin subunit whose amino acid sequence corresponds to the product of the yagZ (renamed ecpA) gene present in all E. coli genomes sequenced to date. ECP production was demonstrated in 121 (71.6%) of a total of 169 ecpA ؉ strains representing intestinal and extraintestinal pathogenic as well as normal flora E. coli. High-resolution ultrastructural and immunofluorescence studies demonstrated the presence of abundant peritrichous fibrillar structures emanating from the bacterial surface forming physical bridges between bacteria adhering to cultured epithelial cells. Isogenic ecpA mutants of EHEC O157:H7 or fecal commensal E. coli showed significant reduction in adherence to cultured epithelial cells. Our data suggest that ECP production is a common feature of E. coli colonizing the human gut or other host tissues. ECP is a pilus of EHEC O157:H7 with a potential role in host epithelial cell colonization and may represent a mechanism of adherence of both pathogenic and commensal E. coli.pili ͉ enterohemorrhagic Escherichia coli ͉ normal flora

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“…The genome of E. coli O157:H7 contains 16 loci encoding genes putatively involved in fimbriae or pili biosynthesis (26)(27)(28), but it is unknown how many of them are functional in vivo. Several fimbriae have been identified in EHEC strains, including the sorbitolfermenting EHEC O157 fimbriae plasmid-encoded (SFP) (29), 2 loci-encoding long polar fimbriae (30), curli (31), F9 (a type I pilus homolog) (32), and a type IV pilus (TFP) in LEE-negative non-O157: H7 STEC (33).…”

Section: Introductionmentioning

confidence: 99%

Intestinal adherence associated with type IV pili of enterohemorrhagic Escherichia coli O157:H7

Xicohtencatl‐Cortes¹,

Monteiro-Neto²,

Ledesma³

et al. 2007

J. Clin. Invest.

120

111

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Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes hemorrhagic colitis and hemolytic uremic syndrome (HUS) by colonizing the gut mucosa and producing Shiga toxins (Stx). The only factor clearly demonstrated to play a role in EHEC adherence to intestinal epithelial cells is intimin, which binds host cell integrins and nucleolin, as well as a receptor (Tir) that it injects into the host cell. Here we report that EHEC O157:H7 produces adhesive type IV pili, which we term hemorrhagic coli pilus (HCP), composed of a 19-kDa pilin subunit (HcpA) that is encoded by the hcpA chromosomal gene. HCP were observed as bundles of fibers greater than 10 μm in length that formed physical bridges between bacteria adhering to human and bovine host cells. Sera of HUS patients, but not healthy individuals, recognized HcpA, suggesting that the pili are produced in vivo during EHEC infections. Inactivation of the hcpA gene in EHEC EDL933 resulted in significantly reduced adherence to cultured human intestinal and bovine renal epithelial cells and to porcine and bovine gut explants. An escN mutant, which is unable to translocate Tir, adhered less than the hcpA mutant, suggesting that adherence mediated by intimin-Tir interactions is a prelude to HCP-mediated adherence. An hcpA and stx1,2 triple mutant and an hcpA mutant had similar levels of adherence to bovine and human epithelial cells while a stx1,2 double mutant had only a minor defect in adherence, indicating that HCP-mediated adherence and cytotoxicity are independent events. Our data establish that EHEC O157:H7 HCP are intestinal colonization factors that are likely to contribute to the pathogenic potential of this food-borne pathogen.

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Analysis of fimbrial gene clusters and their expression in enterohaemorrhagic Escherichia coli O157:H7

Cited by 98 publications

References 56 publications

Fimbrial Adhesins Produced by Atypical Enteropathogenic Escherichia coli Strains

Fimbrial Adhesins Produced by Atypical Enteropathogenic Escherichia coli Strains

Commensal and pathogenic Escherichia coli use a common pilus adherence factor for epithelial cell colonization

Intestinal adherence associated with type IV pili of enterohemorrhagic Escherichia coli O157:H7

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