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The Campylobacter jejuni MarR-like transcriptional regulators RrpA and RrpB both influence bacterial responses to oxidative and aerobic stresses.

Gundogdu O, da Silva DT, Mohammad B, Elmi A, Mills DC, Wren BW, Dorrell N - Front Microbiol (2015)

Bottom Line: Mutation of either rrpA or rrpB reduces catalase (KatA) expression.Mutation of either rrpA or rrpB also results in a reduction in the level of katA expression, but this reduction was not observed in the rrpAB double mutant.Together these data indicate a role for both RrpA and RrpB in the C. jejuni peroxide oxidative and aerobic (O2) stress responses, enhancing bacterial survival in vivo and in the environment.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine , London, UK.

ABSTRACT
The ability of the human intestinal pathogen Campylobacter jejuni to respond to oxidative stress is central to bacterial survival both in vivo during infection and in the environment. Re-annotation of the C. jejuni NCTC11168 genome revealed the presence of two MarR-type transcriptional regulators Cj1546 and Cj1556, originally annotated as hypothetical proteins, which we have designated RrpA and RrpB (regulator of response to peroxide) respectively. Previously we demonstrated a role for RrpB in both oxidative and aerobic (O2) stress and that RrpB was a DNA binding protein with auto-regulatory activity, typical of MarR-type transcriptional regulators. In this study, we show that RrpA is also a DNA binding protein and that a rrpA mutant in strain 11168H exhibits increased sensitivity to hydrogen peroxide oxidative stress. Mutation of either rrpA or rrpB reduces catalase (KatA) expression. However, a rrpAB double mutant exhibits higher levels of resistance to hydrogen peroxide oxidative stress, with levels of KatA expression similar to the wild-type strain. Mutation of either rrpA or rrpB also results in a reduction in the level of katA expression, but this reduction was not observed in the rrpAB double mutant. Neither the rrpA nor rrpB mutant exhibits any significant difference in sensitivity to either cumene hydroperoxide or menadione oxidative stresses, but both mutants exhibit a reduced ability to survive aerobic (O2) stress, enhanced biofilm formation and reduced virulence in the Galleria mellonella infection model. The rrpAB double mutant exhibits wild-type levels of biofilm formation and wild-type levels of virulence in the G mellonella infection model. Together these data indicate a role for both RrpA and RrpB in the C. jejuni peroxide oxidative and aerobic (O2) stress responses, enhancing bacterial survival in vivo and in the environment.

No MeSH data available.


Related in: MedlinePlus

Growth curves for C. jejuni 11168H wild-type strain, rrpA mutant, rrpA complement strain (rrpA comp) and rrpAB mutant grown under either microaerobic (A) or aerobic conditions (B) at 37°C (with shaking at 75 rpm) in Brucella broth with bacterial growth assessed by recording the OD600 of the culture at different time points. Bacterial CFU were also assessed at 16 h under aerobic (C) and microaerobic (D) conditions. Asterisks denote a statistically significant difference (*p < 0.05).
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Figure 6: Growth curves for C. jejuni 11168H wild-type strain, rrpA mutant, rrpA complement strain (rrpA comp) and rrpAB mutant grown under either microaerobic (A) or aerobic conditions (B) at 37°C (with shaking at 75 rpm) in Brucella broth with bacterial growth assessed by recording the OD600 of the culture at different time points. Bacterial CFU were also assessed at 16 h under aerobic (C) and microaerobic (D) conditions. Asterisks denote a statistically significant difference (*p < 0.05).

Mentions: The rrpA mutant was grown under microaerobic and aerobic conditions and growth assessed by measuring the OD600 at different time points. No significant differences were observed in the bacterial growth profile when comparing the wild-type strain, rrpA mutant, rrpAB mutant and the rrpA comp strain under microaerobic conditions (Figure 6A). Interestingly, under aerobic conditions, the rrpA mutant displayed a reduced growth profile compared to the 11168H wild-type strain, rrpAB mutant and the rrpA comp strains (Figure 6B). In addition to OD600, the CFUs were also assessed under microaerobic and aerobic conditions for a number of strains at 16 h. No differences in growth rates compared to the wild-type strain were observed under microaerobic growth conditions (Figure 6C). However, differences were observed under aerobic growth conditions. Both the rrpA and rrpB mutants exhibited reduced CFU compared to the wild-type strain (Figure 6D). These results indicate RrpA and RrpB may also play a role in regulating the aerobic (O2) stress response in C. jejuni.


The Campylobacter jejuni MarR-like transcriptional regulators RrpA and RrpB both influence bacterial responses to oxidative and aerobic stresses.

Gundogdu O, da Silva DT, Mohammad B, Elmi A, Mills DC, Wren BW, Dorrell N - Front Microbiol (2015)

Growth curves for C. jejuni 11168H wild-type strain, rrpA mutant, rrpA complement strain (rrpA comp) and rrpAB mutant grown under either microaerobic (A) or aerobic conditions (B) at 37°C (with shaking at 75 rpm) in Brucella broth with bacterial growth assessed by recording the OD600 of the culture at different time points. Bacterial CFU were also assessed at 16 h under aerobic (C) and microaerobic (D) conditions. Asterisks denote a statistically significant difference (*p < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508579&req=5

Figure 6: Growth curves for C. jejuni 11168H wild-type strain, rrpA mutant, rrpA complement strain (rrpA comp) and rrpAB mutant grown under either microaerobic (A) or aerobic conditions (B) at 37°C (with shaking at 75 rpm) in Brucella broth with bacterial growth assessed by recording the OD600 of the culture at different time points. Bacterial CFU were also assessed at 16 h under aerobic (C) and microaerobic (D) conditions. Asterisks denote a statistically significant difference (*p < 0.05).
Mentions: The rrpA mutant was grown under microaerobic and aerobic conditions and growth assessed by measuring the OD600 at different time points. No significant differences were observed in the bacterial growth profile when comparing the wild-type strain, rrpA mutant, rrpAB mutant and the rrpA comp strain under microaerobic conditions (Figure 6A). Interestingly, under aerobic conditions, the rrpA mutant displayed a reduced growth profile compared to the 11168H wild-type strain, rrpAB mutant and the rrpA comp strains (Figure 6B). In addition to OD600, the CFUs were also assessed under microaerobic and aerobic conditions for a number of strains at 16 h. No differences in growth rates compared to the wild-type strain were observed under microaerobic growth conditions (Figure 6C). However, differences were observed under aerobic growth conditions. Both the rrpA and rrpB mutants exhibited reduced CFU compared to the wild-type strain (Figure 6D). These results indicate RrpA and RrpB may also play a role in regulating the aerobic (O2) stress response in C. jejuni.

Bottom Line: Mutation of either rrpA or rrpB reduces catalase (KatA) expression.Mutation of either rrpA or rrpB also results in a reduction in the level of katA expression, but this reduction was not observed in the rrpAB double mutant.Together these data indicate a role for both RrpA and RrpB in the C. jejuni peroxide oxidative and aerobic (O2) stress responses, enhancing bacterial survival in vivo and in the environment.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine , London, UK.

ABSTRACT
The ability of the human intestinal pathogen Campylobacter jejuni to respond to oxidative stress is central to bacterial survival both in vivo during infection and in the environment. Re-annotation of the C. jejuni NCTC11168 genome revealed the presence of two MarR-type transcriptional regulators Cj1546 and Cj1556, originally annotated as hypothetical proteins, which we have designated RrpA and RrpB (regulator of response to peroxide) respectively. Previously we demonstrated a role for RrpB in both oxidative and aerobic (O2) stress and that RrpB was a DNA binding protein with auto-regulatory activity, typical of MarR-type transcriptional regulators. In this study, we show that RrpA is also a DNA binding protein and that a rrpA mutant in strain 11168H exhibits increased sensitivity to hydrogen peroxide oxidative stress. Mutation of either rrpA or rrpB reduces catalase (KatA) expression. However, a rrpAB double mutant exhibits higher levels of resistance to hydrogen peroxide oxidative stress, with levels of KatA expression similar to the wild-type strain. Mutation of either rrpA or rrpB also results in a reduction in the level of katA expression, but this reduction was not observed in the rrpAB double mutant. Neither the rrpA nor rrpB mutant exhibits any significant difference in sensitivity to either cumene hydroperoxide or menadione oxidative stresses, but both mutants exhibit a reduced ability to survive aerobic (O2) stress, enhanced biofilm formation and reduced virulence in the Galleria mellonella infection model. The rrpAB double mutant exhibits wild-type levels of biofilm formation and wild-type levels of virulence in the G mellonella infection model. Together these data indicate a role for both RrpA and RrpB in the C. jejuni peroxide oxidative and aerobic (O2) stress responses, enhancing bacterial survival in vivo and in the environment.

No MeSH data available.


Related in: MedlinePlus