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Defects in polynucleotide phosphorylase impairs virulence in Escherichia coli O157:H7.

Hu J, Zhu MJ - Front Microbiol (2015)

Bottom Line: To gain insights into its roles in E. coli O157:H7 virulence, pnp deletion mutants were generated and the major virulence factors were compared to their parental wild type strains.Deletion of pnp in E. coli O157:H7 dramatically decreased stx2 mRNA expression and Stx2 protein production, and impaired lambdoid prophage activation in E. coli O157:H7.Collectively, data indicate that PNPase has pleiotropic effects on the virulence of E. coli O157:H7.

View Article: PubMed Central - PubMed

Affiliation: School of Food Science, Washington State University, Pullman, WA USA ; Department of Animal Science, University of Wyoming, Laramie, WY USA.

ABSTRACT
Polynucleotide phosphorylase (PNPase) is reported to regulate virulence in Salmonella, Yersinia sp. and Campylobacter jejuni, yet its role in Escherichia coli O157:H7 has not been investigated. To gain insights into its roles in E. coli O157:H7 virulence, pnp deletion mutants were generated and the major virulence factors were compared to their parental wild type strains. Deletion of pnp in E. coli O157:H7 dramatically decreased stx2 mRNA expression and Stx2 protein production, and impaired lambdoid prophage activation in E. coli O157:H7. Quantitative PCR further confirmed that the Stx2 phage lytic growth was repressed by pnp deletion. Consistent with reduced Stx2 production and Stx2 phage activation, the transcriptional levels of genes involved in phage lysis and replication were down-regulated. In addition, disruption of pnp in E. coli O157:H7 decreased its adhesion to intestinal epithelial cells as well as cattle colonic explant tissues. On the other hand, PNPase inactivation in E. coli O157:H7 enhanced Tir protein content and the transcription of type three secretion system components, including genes encoding intimin, Tir, and EspB as well as locus of enterocyte and effacement positive regulator, Ler. Collectively, data indicate that PNPase has pleiotropic effects on the virulence of E. coli O157:H7.

No MeSH data available.


Related in: MedlinePlus

Adhesion of E. coli O157:H7 to intestinal epithelium. (A) HT-29 colonic epithelial cell line; (B) Cattle colonic explant tissues. EDL933: wild-type E. coli O157:H7 strain; EDL933 Δpnp: EDL933 pnp deletion mutant strain, **P < 0.01 (Mean ± SEM; n = 8).
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Figure 3: Adhesion of E. coli O157:H7 to intestinal epithelium. (A) HT-29 colonic epithelial cell line; (B) Cattle colonic explant tissues. EDL933: wild-type E. coli O157:H7 strain; EDL933 Δpnp: EDL933 pnp deletion mutant strain, **P < 0.01 (Mean ± SEM; n = 8).

Mentions: In addition to phage encoding Stx2 production, E. coli O157:H7 has a LEE chromosomal pathogenicity island that encoding T3SS apparatus and effectors, mediating intimate contact to epithelial cells (McDaniel et al., 1995). We further evaluated the significance of pnp deletion in E. coli O157: H7 epithelial adhesion. Deletion of pnp in E. coli O157: H7 EDL933 strain decreased its adhesion to colonic epithelial HT-29 cells by approximately twofold (Figure 3A). Consistently, adhesion to cattle colonic gut explant was reduced about fourfold in EDL933Δpnp (Figure 3B).


Defects in polynucleotide phosphorylase impairs virulence in Escherichia coli O157:H7.

Hu J, Zhu MJ - Front Microbiol (2015)

Adhesion of E. coli O157:H7 to intestinal epithelium. (A) HT-29 colonic epithelial cell line; (B) Cattle colonic explant tissues. EDL933: wild-type E. coli O157:H7 strain; EDL933 Δpnp: EDL933 pnp deletion mutant strain, **P < 0.01 (Mean ± SEM; n = 8).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4538292&req=5

Figure 3: Adhesion of E. coli O157:H7 to intestinal epithelium. (A) HT-29 colonic epithelial cell line; (B) Cattle colonic explant tissues. EDL933: wild-type E. coli O157:H7 strain; EDL933 Δpnp: EDL933 pnp deletion mutant strain, **P < 0.01 (Mean ± SEM; n = 8).
Mentions: In addition to phage encoding Stx2 production, E. coli O157:H7 has a LEE chromosomal pathogenicity island that encoding T3SS apparatus and effectors, mediating intimate contact to epithelial cells (McDaniel et al., 1995). We further evaluated the significance of pnp deletion in E. coli O157: H7 epithelial adhesion. Deletion of pnp in E. coli O157: H7 EDL933 strain decreased its adhesion to colonic epithelial HT-29 cells by approximately twofold (Figure 3A). Consistently, adhesion to cattle colonic gut explant was reduced about fourfold in EDL933Δpnp (Figure 3B).

Bottom Line: To gain insights into its roles in E. coli O157:H7 virulence, pnp deletion mutants were generated and the major virulence factors were compared to their parental wild type strains.Deletion of pnp in E. coli O157:H7 dramatically decreased stx2 mRNA expression and Stx2 protein production, and impaired lambdoid prophage activation in E. coli O157:H7.Collectively, data indicate that PNPase has pleiotropic effects on the virulence of E. coli O157:H7.

View Article: PubMed Central - PubMed

Affiliation: School of Food Science, Washington State University, Pullman, WA USA ; Department of Animal Science, University of Wyoming, Laramie, WY USA.

ABSTRACT
Polynucleotide phosphorylase (PNPase) is reported to regulate virulence in Salmonella, Yersinia sp. and Campylobacter jejuni, yet its role in Escherichia coli O157:H7 has not been investigated. To gain insights into its roles in E. coli O157:H7 virulence, pnp deletion mutants were generated and the major virulence factors were compared to their parental wild type strains. Deletion of pnp in E. coli O157:H7 dramatically decreased stx2 mRNA expression and Stx2 protein production, and impaired lambdoid prophage activation in E. coli O157:H7. Quantitative PCR further confirmed that the Stx2 phage lytic growth was repressed by pnp deletion. Consistent with reduced Stx2 production and Stx2 phage activation, the transcriptional levels of genes involved in phage lysis and replication were down-regulated. In addition, disruption of pnp in E. coli O157:H7 decreased its adhesion to intestinal epithelial cells as well as cattle colonic explant tissues. On the other hand, PNPase inactivation in E. coli O157:H7 enhanced Tir protein content and the transcription of type three secretion system components, including genes encoding intimin, Tir, and EspB as well as locus of enterocyte and effacement positive regulator, Ler. Collectively, data indicate that PNPase has pleiotropic effects on the virulence of E. coli O157:H7.

No MeSH data available.


Related in: MedlinePlus