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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

Effects of PNPase on the virulence factors of E. coli O157:H7 EDL933, Sakai, and 86-24 strains. (A) Stx 2A and Tir protein contents by immunoblotting; (B)stx2 phage DNA content by qPCR. □: wild-type (WT); ■: pnp deletion mutant (Δpnp). ***P < 0.001 (Mean ± SEM, n = 4).
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Figure 5: Effects of PNPase on the virulence factors of E. coli O157:H7 EDL933, Sakai, and 86-24 strains. (A) Stx 2A and Tir protein contents by immunoblotting; (B)stx2 phage DNA content by qPCR. □: wild-type (WT); ■: pnp deletion mutant (Δpnp). ***P < 0.001 (Mean ± SEM, n = 4).

Mentions: To confirm the results from E. coli O157:H7 strain EDL933, we further examined the Stx2 production and Stx2 phage lytic activation in E. coli O157:H7 strain Sakai and 86-24. Consistent to the finding in EDL933 strain, the pnp deletion decreased Stx2 production (Figure 5A) and impaired Stx2 phage lytic growth (Figure 5B) in Sakai and 86-24. As in strain EDL933, Tir protein content was enhanced in both E. coli O157:H7 strain Sakai and 86-24 (Figure 5A).


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

Hu J, Zhu MJ - Front Microbiol (2015)

Effects of PNPase on the virulence factors of E. coli O157:H7 EDL933, Sakai, and 86-24 strains. (A) Stx 2A and Tir protein contents by immunoblotting; (B)stx2 phage DNA content by qPCR. □: wild-type (WT); ■: pnp deletion mutant (Δpnp). ***P < 0.001 (Mean ± SEM, n = 4).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: Effects of PNPase on the virulence factors of E. coli O157:H7 EDL933, Sakai, and 86-24 strains. (A) Stx 2A and Tir protein contents by immunoblotting; (B)stx2 phage DNA content by qPCR. □: wild-type (WT); ■: pnp deletion mutant (Δpnp). ***P < 0.001 (Mean ± SEM, n = 4).
Mentions: To confirm the results from E. coli O157:H7 strain EDL933, we further examined the Stx2 production and Stx2 phage lytic activation in E. coli O157:H7 strain Sakai and 86-24. Consistent to the finding in EDL933 strain, the pnp deletion decreased Stx2 production (Figure 5A) and impaired Stx2 phage lytic growth (Figure 5B) in Sakai and 86-24. As in strain EDL933, Tir protein content was enhanced in both E. coli O157:H7 strain Sakai and 86-24 (Figure 5A).

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