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Regulation of oxidative stress response by CosR, an essential response regulator in Campylobacter jejuni.

Hwang S, Kim M, Ryu S, Jeon B - PLoS ONE (2011)

Bottom Line: Interestingly, the level of CosR protein was significantly reduced by paraquat (a superoxide generator) but not by hydrogen peroxide.Consistent with the overall negative regulation of oxidative stress defense proteins by CosR, the CosR knockdown by antisense rendered C. jejuni more resistant to oxidative stress compared to the wild type.Overall, this study reveals the important role played by the essential response regulator CosR in the oxidative stress defense of C. jejuni.

View Article: PubMed Central - PubMed

Affiliation: Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University, Seoul, Korea.

ABSTRACT
CosR (Campylobacter oxidative stress regulator; Cj0355c) is an OmpR-type response regulator essential for the viability of Campylobacter jejuni, a leading foodborne pathogen causing human gastroenteritis worldwide. Despite importance, the function of CosR remains completely unknown mainly because of cell death caused by its knockout mutation. To overcome this technical limitation, in this study, antisense technology was used to investigate the regulatory function of CosR by modulating the level of CosR expression. Two-dimensional gel electrophoresis (2DGE) was performed to identify the CosR regulon either by suppressing CosR expression with antisense peptide nucleic acid (PNA) or by overexpressing CosR in C. jejuni. According to the results of 2DGE, CosR regulated 32 proteins involved in various cellular processes. Notably, CosR negatively regulated a few key proteins of the oxidative stress response of C. jejuni, such as SodB, Dps, Rrc and LuxS, whereas CosR positively controlled AhpC. Electrophoretic mobility shift assay showed that CosR directly bound to the promoter region of the oxidative stress genes. DNase I footprinting assays identified 21-bp CosR binding sequences in the sodB and ahpC promoters, suggesting CosR specifically recognizes and binds to the regulated genes. Interestingly, the level of CosR protein was significantly reduced by paraquat (a superoxide generator) but not by hydrogen peroxide. Consistent with the overall negative regulation of oxidative stress defense proteins by CosR, the CosR knockdown by antisense rendered C. jejuni more resistant to oxidative stress compared to the wild type. Overall, this study reveals the important role played by the essential response regulator CosR in the oxidative stress defense of C. jejuni.

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Effect of CosR on oxidative stress resistance.Changes in the viability of C. jejuni by paraquat (A) and hydrogen peroxide (B); 1 mM each oxidant for 1 hr exposure. Viability is indicated by percent change in viable count before and after each oxidant treatment. CosR knockdown was achieved with 1.5 µM CosR-PNA. Results show the average and standard deviation of triplicate samples from a single experiment. The experiment was repeated three times with similar results. *: P<0.05; **: P<0.01; ***: P<0.001. The P values are the results of one-way ANOVA analysis of variance with Dunnett's post-tests at a 95% confidence interval using Prism software (version 5.01; GraphPad Software Inc., USA).
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pone-0022300-g008: Effect of CosR on oxidative stress resistance.Changes in the viability of C. jejuni by paraquat (A) and hydrogen peroxide (B); 1 mM each oxidant for 1 hr exposure. Viability is indicated by percent change in viable count before and after each oxidant treatment. CosR knockdown was achieved with 1.5 µM CosR-PNA. Results show the average and standard deviation of triplicate samples from a single experiment. The experiment was repeated three times with similar results. *: P<0.05; **: P<0.01; ***: P<0.001. The P values are the results of one-way ANOVA analysis of variance with Dunnett's post-tests at a 95% confidence interval using Prism software (version 5.01; GraphPad Software Inc., USA).

Mentions: Because CosR regulates several important oxidative stress genes in C. jejuni, susceptibility to oxidative stress was measured at different CosR levels. Viable counts were determined before and after 1 hr exposure to oxidant. The C. jejuni strain overexpressing CosR was more susceptible to paraquat and H2O2 compared to the wild type, whereas CosR knockdown by antisense rendered C. jejuni more resistant to oxidative stress (Figure 8). These results showed that CosR significantly contributes to the oxidative stress resistance of C. jejuni.


Regulation of oxidative stress response by CosR, an essential response regulator in Campylobacter jejuni.

Hwang S, Kim M, Ryu S, Jeon B - PLoS ONE (2011)

Effect of CosR on oxidative stress resistance.Changes in the viability of C. jejuni by paraquat (A) and hydrogen peroxide (B); 1 mM each oxidant for 1 hr exposure. Viability is indicated by percent change in viable count before and after each oxidant treatment. CosR knockdown was achieved with 1.5 µM CosR-PNA. Results show the average and standard deviation of triplicate samples from a single experiment. The experiment was repeated three times with similar results. *: P<0.05; **: P<0.01; ***: P<0.001. The P values are the results of one-way ANOVA analysis of variance with Dunnett's post-tests at a 95% confidence interval using Prism software (version 5.01; GraphPad Software Inc., USA).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3139631&req=5

pone-0022300-g008: Effect of CosR on oxidative stress resistance.Changes in the viability of C. jejuni by paraquat (A) and hydrogen peroxide (B); 1 mM each oxidant for 1 hr exposure. Viability is indicated by percent change in viable count before and after each oxidant treatment. CosR knockdown was achieved with 1.5 µM CosR-PNA. Results show the average and standard deviation of triplicate samples from a single experiment. The experiment was repeated three times with similar results. *: P<0.05; **: P<0.01; ***: P<0.001. The P values are the results of one-way ANOVA analysis of variance with Dunnett's post-tests at a 95% confidence interval using Prism software (version 5.01; GraphPad Software Inc., USA).
Mentions: Because CosR regulates several important oxidative stress genes in C. jejuni, susceptibility to oxidative stress was measured at different CosR levels. Viable counts were determined before and after 1 hr exposure to oxidant. The C. jejuni strain overexpressing CosR was more susceptible to paraquat and H2O2 compared to the wild type, whereas CosR knockdown by antisense rendered C. jejuni more resistant to oxidative stress (Figure 8). These results showed that CosR significantly contributes to the oxidative stress resistance of C. jejuni.

Bottom Line: Interestingly, the level of CosR protein was significantly reduced by paraquat (a superoxide generator) but not by hydrogen peroxide.Consistent with the overall negative regulation of oxidative stress defense proteins by CosR, the CosR knockdown by antisense rendered C. jejuni more resistant to oxidative stress compared to the wild type.Overall, this study reveals the important role played by the essential response regulator CosR in the oxidative stress defense of C. jejuni.

View Article: PubMed Central - PubMed

Affiliation: Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University, Seoul, Korea.

ABSTRACT
CosR (Campylobacter oxidative stress regulator; Cj0355c) is an OmpR-type response regulator essential for the viability of Campylobacter jejuni, a leading foodborne pathogen causing human gastroenteritis worldwide. Despite importance, the function of CosR remains completely unknown mainly because of cell death caused by its knockout mutation. To overcome this technical limitation, in this study, antisense technology was used to investigate the regulatory function of CosR by modulating the level of CosR expression. Two-dimensional gel electrophoresis (2DGE) was performed to identify the CosR regulon either by suppressing CosR expression with antisense peptide nucleic acid (PNA) or by overexpressing CosR in C. jejuni. According to the results of 2DGE, CosR regulated 32 proteins involved in various cellular processes. Notably, CosR negatively regulated a few key proteins of the oxidative stress response of C. jejuni, such as SodB, Dps, Rrc and LuxS, whereas CosR positively controlled AhpC. Electrophoretic mobility shift assay showed that CosR directly bound to the promoter region of the oxidative stress genes. DNase I footprinting assays identified 21-bp CosR binding sequences in the sodB and ahpC promoters, suggesting CosR specifically recognizes and binds to the regulated genes. Interestingly, the level of CosR protein was significantly reduced by paraquat (a superoxide generator) but not by hydrogen peroxide. Consistent with the overall negative regulation of oxidative stress defense proteins by CosR, the CosR knockdown by antisense rendered C. jejuni more resistant to oxidative stress compared to the wild type. Overall, this study reveals the important role played by the essential response regulator CosR in the oxidative stress defense of C. jejuni.

Show MeSH
Related in: MedlinePlus