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Phenotypic and transcriptional analysis of the osmotic regulator OmpR in Yersinia pestis.

Gao H, Zhang Y, Han Y, Yang L, Liu X, Guo Z, Tan Y, Huang X, Zhou D, Yang R - BMC Microbiol. (2011)

Bottom Line: The ompR mutation likely did not affect the virulence of Y. pestis strain 201 that was a human-avirulent enzootic strain.Real-time RT-PCR or lacZ fusion reporter assay further validated 16 OmpR-dependent genes, for which OmpR consensus-like sequences were found within their upstream DNA regions. ompC, F, X, and R were up-regulated dramatically with the increase of medium osmolarity, which was mediated by OmpR occupying the target promoter regions in a tandem manner.The main difference is that ompF expression is not repressed at high osmolarity in Y. pestis, which is likely due to the absence of a promoter-distal OmpR-binding site for ompF.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China.

ABSTRACT

Background: The osmotic regulator OmpR in Escherichia coli regulates differentially the expression of major porin proteins OmpF and OmpC. In Yersinia enterocolitica and Y. pseudotuberculosis, OmpR is required for both virulence and survival within macrophages. However, the phenotypic and regulatory roles of OmpR in Y. pestis are not yet fully understood.

Results: Y. pestis OmpR is involved in building resistance against phagocytosis and controls the adaptation to various stressful conditions met in macrophages. The ompR mutation likely did not affect the virulence of Y. pestis strain 201 that was a human-avirulent enzootic strain. The microarray-based comparative transcriptome analysis disclosed a set of 224 genes whose expressions were affected by the ompR mutation, indicating the global regulatory role of OmpR in Y. pestis. Real-time RT-PCR or lacZ fusion reporter assay further validated 16 OmpR-dependent genes, for which OmpR consensus-like sequences were found within their upstream DNA regions. ompC, F, X, and R were up-regulated dramatically with the increase of medium osmolarity, which was mediated by OmpR occupying the target promoter regions in a tandem manner.

Conclusion: OmpR contributes to the resistance against phagocytosis or survival within macrophages, which is conserved in the pathogenic yersiniae. Y. pestis OmpR regulates ompC, F, X, and R directly through OmpR-promoter DNA association. There is an inducible expressions of the pore-forming proteins OmpF, C, and × at high osmolarity in Y. pestis, in contrast to the reciprocal regulation of them in E. coli. The main difference is that ompF expression is not repressed at high osmolarity in Y. pestis, which is likely due to the absence of a promoter-distal OmpR-binding site for ompF.

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Autoregulation of OmpR but not CRP. a) LacZ fusion reporter. A recombinant pRW50 that contained a promoter-proximal region of ompR was transformed into WT or ΔompR to determine the promoter activity. This figure shows the decreased mean fold for the ompR promoter activity in ΔompR relative to WT. d) DNase I footprinting. For DNase I digestion, the labeled promoter-proximal region of ompR was incubated with various amounts of purified, acetyl phosphate-treated His-OmpR (lanes 1, 2, and 3 contained 0, 10 and 20 pmol, respectively). Lanes G, A, T, and C represent the Sanger sequencing reactions, and the protected regions (bold lines) are indicated on the right-hand side. The numbers indicate the nucleotide positions upstream the transcriptional start sites.
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Figure 3: Autoregulation of OmpR but not CRP. a) LacZ fusion reporter. A recombinant pRW50 that contained a promoter-proximal region of ompR was transformed into WT or ΔompR to determine the promoter activity. This figure shows the decreased mean fold for the ompR promoter activity in ΔompR relative to WT. d) DNase I footprinting. For DNase I digestion, the labeled promoter-proximal region of ompR was incubated with various amounts of purified, acetyl phosphate-treated His-OmpR (lanes 1, 2, and 3 contained 0, 10 and 20 pmol, respectively). Lanes G, A, T, and C represent the Sanger sequencing reactions, and the protected regions (bold lines) are indicated on the right-hand side. The numbers indicate the nucleotide positions upstream the transcriptional start sites.

Mentions: According to the lacZ fusion reporter assay (Figure 3a); there was a more than 10-fold decrease of the ompR promoter activity in ΔompR relative to WT at 0.5 M sorbitol, thereby indicating that OmpR stimulated the promoter activity of its own gene. The subsequent DNase I footprinting experiments (Figure 3a) showed that His-OmpR-P protected a single region within the ompR promoter. Therefore, OmpR stimulated its own gene at the transcriptional level, which was mediated through the binding of OmpR-P to its own promoter.


Phenotypic and transcriptional analysis of the osmotic regulator OmpR in Yersinia pestis.

Gao H, Zhang Y, Han Y, Yang L, Liu X, Guo Z, Tan Y, Huang X, Zhou D, Yang R - BMC Microbiol. (2011)

Autoregulation of OmpR but not CRP. a) LacZ fusion reporter. A recombinant pRW50 that contained a promoter-proximal region of ompR was transformed into WT or ΔompR to determine the promoter activity. This figure shows the decreased mean fold for the ompR promoter activity in ΔompR relative to WT. d) DNase I footprinting. For DNase I digestion, the labeled promoter-proximal region of ompR was incubated with various amounts of purified, acetyl phosphate-treated His-OmpR (lanes 1, 2, and 3 contained 0, 10 and 20 pmol, respectively). Lanes G, A, T, and C represent the Sanger sequencing reactions, and the protected regions (bold lines) are indicated on the right-hand side. The numbers indicate the nucleotide positions upstream the transcriptional start sites.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3050692&req=5

Figure 3: Autoregulation of OmpR but not CRP. a) LacZ fusion reporter. A recombinant pRW50 that contained a promoter-proximal region of ompR was transformed into WT or ΔompR to determine the promoter activity. This figure shows the decreased mean fold for the ompR promoter activity in ΔompR relative to WT. d) DNase I footprinting. For DNase I digestion, the labeled promoter-proximal region of ompR was incubated with various amounts of purified, acetyl phosphate-treated His-OmpR (lanes 1, 2, and 3 contained 0, 10 and 20 pmol, respectively). Lanes G, A, T, and C represent the Sanger sequencing reactions, and the protected regions (bold lines) are indicated on the right-hand side. The numbers indicate the nucleotide positions upstream the transcriptional start sites.
Mentions: According to the lacZ fusion reporter assay (Figure 3a); there was a more than 10-fold decrease of the ompR promoter activity in ΔompR relative to WT at 0.5 M sorbitol, thereby indicating that OmpR stimulated the promoter activity of its own gene. The subsequent DNase I footprinting experiments (Figure 3a) showed that His-OmpR-P protected a single region within the ompR promoter. Therefore, OmpR stimulated its own gene at the transcriptional level, which was mediated through the binding of OmpR-P to its own promoter.

Bottom Line: The ompR mutation likely did not affect the virulence of Y. pestis strain 201 that was a human-avirulent enzootic strain.Real-time RT-PCR or lacZ fusion reporter assay further validated 16 OmpR-dependent genes, for which OmpR consensus-like sequences were found within their upstream DNA regions. ompC, F, X, and R were up-regulated dramatically with the increase of medium osmolarity, which was mediated by OmpR occupying the target promoter regions in a tandem manner.The main difference is that ompF expression is not repressed at high osmolarity in Y. pestis, which is likely due to the absence of a promoter-distal OmpR-binding site for ompF.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China.

ABSTRACT

Background: The osmotic regulator OmpR in Escherichia coli regulates differentially the expression of major porin proteins OmpF and OmpC. In Yersinia enterocolitica and Y. pseudotuberculosis, OmpR is required for both virulence and survival within macrophages. However, the phenotypic and regulatory roles of OmpR in Y. pestis are not yet fully understood.

Results: Y. pestis OmpR is involved in building resistance against phagocytosis and controls the adaptation to various stressful conditions met in macrophages. The ompR mutation likely did not affect the virulence of Y. pestis strain 201 that was a human-avirulent enzootic strain. The microarray-based comparative transcriptome analysis disclosed a set of 224 genes whose expressions were affected by the ompR mutation, indicating the global regulatory role of OmpR in Y. pestis. Real-time RT-PCR or lacZ fusion reporter assay further validated 16 OmpR-dependent genes, for which OmpR consensus-like sequences were found within their upstream DNA regions. ompC, F, X, and R were up-regulated dramatically with the increase of medium osmolarity, which was mediated by OmpR occupying the target promoter regions in a tandem manner.

Conclusion: OmpR contributes to the resistance against phagocytosis or survival within macrophages, which is conserved in the pathogenic yersiniae. Y. pestis OmpR regulates ompC, F, X, and R directly through OmpR-promoter DNA association. There is an inducible expressions of the pore-forming proteins OmpF, C, and × at high osmolarity in Y. pestis, in contrast to the reciprocal regulation of them in E. coli. The main difference is that ompF expression is not repressed at high osmolarity in Y. pestis, which is likely due to the absence of a promoter-distal OmpR-binding site for ompF.

Show MeSH
Related in: MedlinePlus