Multiple mechanisms responsible for strong Congo-red-binding variants of<i>Escherichia coli</i>O157:H7 strains

Chen, Chin-Yi; Nguyen, Ly-Huong T.; Cottrell, Bryan J.; Irwin, Peter L.; Uhlich, Gaylen A.

doi:10.1093/femspd/ftv123

Cited by 19 publications

(19 citation statements)

References 40 publications

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“…This observation was at variance with previous reports associating mutations in the rpoS or rcsB genes with curli-expressing strains only (30)(31)(32). The current results indicate that genotypic changes regulating the C ϩϩ , C ϩ , or C Ϫ curli phenotype differ from strain to strain and may be multifactorial (36).…”

contrasting

confidence: 99%

Curli Temper Adherence of Escherichia coli O157:H7 to Squamous Epithelial Cells from the Bovine Recto-Anal Junction in a Strain-Dependent Manner

Kudva

Carter

Sharma

et al. 2017

Appl Environ Microbiol

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Our recent studies have shown that intimin and the locus of enterocyte effacement-encoded proteins do not play a role in Escherichia coli O157:H7 (O157) adherence to the bovine recto-anal junction squamous epithelial (RSE) cells. To define factors that play a contributory role, we investigated the role of curli, fimbrial adhesins commonly implicated in adherence to various fomites and plant and human epithelial cells, in O157 adherence to RSE cells. Specifically, we examined (i) wild-type strains of O157; (ii) curli variants of O157 strains; (iii) isogenic curli deletion mutants of O157; and (iv) adherence inhibition of O157 using anti-curlin sera. Results of these experiments conducted under stringent conditions suggest that curli do not solely contribute to O157 adherence to RSE cells and in fact demonstrate a modulating effect on O157 adherence to RSE cells in contrast to HEp-2 cells (human epidermoid carcinoma of the larynx cells with HeLa contamination). The absence of curli and presence of blocking anti-curli antibodies enhanced O157-RSE cell interactions among some strains, thus alluding to a spatial, tempering effect of curli on O157 adherence to RSE cells when present. At the same time, the presence or absence of curli did not alter RSE cell adherence patterns of another O157 strain. These observations are at variance with the reported role of curli in O157 adherence to human cell lines such as HEp-2 and need to be factored in when developing antiadherence modalities for preharvest control of O157 in cattle.IMPORTANCE This study demonstrated that O157 strains interact with epithelial cells in a host-specific manner. The fimbriae/adhesins that are significant for adherence to human cell lines may not have a role or may have a modulating role in O157 adherence to bovine cells. Targeting such adhesins may not prevent O157 attachment to bovine cells but instead may result in improved adherence. Hence, conducting host-specific evaluations is critical when selecting targets for O157 control strategies.KEYWORDS HEp-2, O157, RSE, STEC, adherence, bovine, curli, fimbriae, recto-anal junction E scherichia coli O157:H7 (O157) is a foodborne human-infecting pathogen that causes an estimated 63,153 illnesses, 2,138 hospitalizations, and 20 deaths annually in the United States (1-8). Although a 44% decline in O157 cases was reported for the year 2010, over the past 6 years at least 13 different multistate O157 outbreaks have occurred, many of which have had a direct link to beef or produce possibly contami-

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confidence: 99%

Curli Temper Adherence of Escherichia coli O157:H7 to Squamous Epithelial Cells from the Bovine Recto-Anal Junction in a Strain-Dependent Manner

Kudva

Carter

Sharma

et al. 2017

Appl Environ Microbiol

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“…A recent report indicated that the EHEC ΔrcsB strain displays diminished binding of the dye Congo red, suggesting alterations in its surface structures (37). We found that the C. rodentium ΔrcsB strain had increased Congo red binding under all growth conditions tested (Table S5).…”

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confidence: 54%

Systematic Analysis of Two-Component Systems in Citrobacter rodentium Reveals Positive and Negative Roles in Virulence

et al. 2017

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Citrobacter rodentium is a murine pathogen used to model intestinal infections caused by the human diarrheal pathogens enterohemorrhagic and enteropathogenic Escherichia coli. During infection, bacteria use two-component systems (TCSs) to detect changing environmental cues within the host, allowing for rapid adaptation by altering the expression of specific genes. In this study, 26 TCSs were identified in C. rodentium, and quantitative PCR (qPCR) analysis showed that they are all expressed during murine infection. These TCSs were individually deleted, and the in vitro and in vivo effects were analyzed to determine the functional consequences. In vitro analyses only revealed minor differences, and surprisingly, type III secretion (T3S) was only affected in the ΔarcA strain. Murine infections identified 7 mutants with either attenuated or increased virulence. In agreement with the in vitro T3S assay, the ΔarcA strain was attenuated and defective in colonization and cell adherence. The ΔrcsB strain was among the most highly attenuated strains. The decrease in virulence of this strain may be associated with changes to the cell surface, as Congo red binding was altered, and qPCR revealed that expression of the wcaA gene, which has been implicated in colanic acid production in other bacteria, was drastically downregulated. The ΔuvrY strain exhibited increased virulence compared to the wild type, which was associated with a significant increase in bacterial burden within the mesenteric lymph nodes. The systematic analysis of virulence-associated TCSs and investigation of their functions during infection may open new avenues for drug development.

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“…Pathogenic and commensal E. coli strains show variability in rdar biofilm formation and regulation (Bokranz et al., ; Hammar et al., ; Kai‐Larsen et al., ; Wang, Lünsdorf, Ehren, Brauner, & Römling, ). For example, E. coli O157:H7 regularly exhibit a downregulated rdar morphotype and csgD expression via either mutation of rcsB encoding a response regulator of the Rcs two component system (Sharma et al., ), or due to a prophage insertion in the csgD specific transcriptional regulator mlrA rendering the gene inactive (Chen, Nguyen, Cottrell, Irwin, & Uhlich, ). E. coli K‐12 derivatives do not produce cellulose due to a stop codon in bcsQ (Serra et al., ).…”

Section: Discussionmentioning

confidence: 99%

Alterations of c‐di‐GMP turnover proteins modulate semi‐constitutive rdar biofilm formation in commensal and uropathogenic Escherichia coli

Cimdins

Simm

et al. 2017

MicrobiologyOpen

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Agar plate‐based biofilm of enterobacteria like Escherichia coli is characterized by expression of the extracellular matrix components amyloid curli and cellulose exopolysaccharide, which can be visually enhanced upon addition of the dye Congo Red, resulting in a red, dry, and rough (rdar) colony morphology. Expression of the rdar morphotype depends on the transcriptional regulator CsgD and occurs predominantly at ambient temperature in model strains. In contrast, commensal and pathogenic isolates frequently express the csgD‐dependent rdar morphotype semi‐constitutively, also at human host body temperature. To unravel the molecular basis of temperature‐independent rdar morphotype expression, biofilm components and c‐di‐GMP turnover proteins of seven commensal and uropathogenic E. coli isolates were analyzed. A diversity within the c‐di‐GMP signaling network was uncovered which suggests alteration of activity of the trigger phosphodiesterase YciR to contribute to (up)regulation of csgD expression and consequently semi‐constitutive rdar morphotype development.

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Multiple mechanisms responsible for strong Congo-red-binding variants ofEscherichia coliO157:H7 strains

Cited by 19 publications

References 40 publications

Curli Temper Adherence of Escherichia coli O157:H7 to Squamous Epithelial Cells from the Bovine Recto-Anal Junction in a Strain-Dependent Manner

Curli Temper Adherence of Escherichia coli O157:H7 to Squamous Epithelial Cells from the Bovine Recto-Anal Junction in a Strain-Dependent Manner

Systematic Analysis of Two-Component Systems in Citrobacter rodentium Reveals Positive and Negative Roles in Virulence

Alterations of c‐di‐GMP turnover proteins modulate semi‐constitutive rdar biofilm formation in commensal and uropathogenic Escherichia coli

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