Alkyl Hydroperoxide Reductase Is the Primary Scavenger of Endogenous Hydrogen Peroxide in Escherichia coli

Abstract

Hydrogen peroxide is generated during aerobic metabolism and is capable of damaging critical biomolecules. However, mutants of Escherichia coli that are devoid of catalase typically exhibit no adverse phenotypes during growth in aerobic media. We discovered that catalase mutants retain the ability to rapidly scavenge H 2 O 2 whether it is formed internally or provided exogenously. Analysis of candidate genes revealed that the residual activity is due to alkyl hydroperoxide reductase (Ahp

The rhodanese RhdA helps Azotobacter vinelandii in maintaining cellular redox balance

“…Notably, analysis of the cydAB transcript could provide insights on CydR inactivation, because expression of cydAB is negatively controlled by this FNR-like Fe-S transcriptional regulator (Wu et al, 1997(Wu et al, , 2000. As stated previously, studies on the role of A. vinelandii alkyl hydroperoxide reductase in managing stress tolerance are lacking, but it seems conceivable that its role should be similar to that of other bacterial AhpCs (Aslund et al, 1999;Ochsner et al, 2000;Seaver and Imlay, 2001;Hishinuma et al, 2006). Accordingly, the high level of ahpC transcript in MV474 proved that defensive activities against oxidants are required when RhdA is lacking.…”

“…Considering that in these enhanced stress conditions growth rates were impaired only in the A. vinelandii RhdA mutant (Cereda et al, 2007(Cereda et al, , 2009, it became conceivable that the rhdA gene product has a role in modulating cellular redox events, thus limiting the oxidative imbalance generated by the presence of the superoxide generator PMS. Regulated adaptive responses to oxidative stress have been extensively studied using E. coli as a model organism (Pomposiello and Demple, 2001;Seaver and Imlay, 2001;Zheng et al, 2001), and it is generally recognized that catalase and alkyl hydroperoxide reductase (the product of ahpC gene) activities are crucial to oxidative stress survival. AhpC is a member of the OxyR regulon, and in E. coli it was found that OxyR can respond to disulfide stress resulting from defects in the systems that maintain an intracellular reducing environment (Aslund et al, 1999).…”

Catalase (KatA) and Alkyl Hydroperoxide Reductase (AhpC) Have Compensatory Roles in Peroxide Stress Resistance and Are Required for Survival, Persistence, and Nasal Colonization inStaphylococcus aureus

“…H 2 O 2 was detected using the amplex red/horseradish peroxidase assay as described by Seaver and Imlay, measuring absorbance at 568 nm (50). Scavenging of H 2 O 2 was measured using exponential-phase cells grown in CT-BHI (CLR was used for measuring 2 M H 2 O 2 scavenging), washed, and resuspended in PBS to an OD 600 of 0.1.…”

“…E. coli AhpC was a more efficient scavenger of low-levels H 2 O 2 than catalase and was denoted the primary scavenger of endogenously produced H 2 O 2 . In comparison, catalase was described as the primary scavenger of H 2 O 2 at high levels (50). Strains lacking catalase and AhpC, Hpx Ϫ cells, displayed an aerobic growth defect, attributed to accumulation of endogenously produced H 2 O 2 and subsequent Fenton reaction-derived DNA damage.…”

“…Further studies revealed that H 2 O 2 -scavenging activity was retained in the catalase mutants due to the presence of alkyl hydroperoxide reductase (AhpC) (50). AhpC is a member of the peroxiredoxin family of enzymes, which have activity against H 2 O 2 , organic peroxides, and peroxynitrite (44).…”