Catalase HPII, heme d-containing; Decomposes hydrogen peroxide into water and oxygen; serves to protect cells from the toxic effects of hydrogen peroxide.

Catalase-peroxidase HPI, heme b-containing; Bifunctional enzyme with both catalase and broad-spectrum peroxidase activity. Displays also NADH oxidase, INH lyase and isonicotinoyl-NAD synthase activity; Belongs to the peroxidase family. Peroxidase/catalase subfamily.

Alkyl hydroperoxide reductase, C22 subunit; Thiol-specific peroxidase that catalyzes the reduction of hydrogen peroxide and organic hydroperoxides to water and alcohols, respectively. Plays a role in cell protection against oxidative stress by detoxifying peroxides. Is the primary scavenger for endogenously generated hydrogen peroxides; Belongs to the peroxiredoxin family. AhpC/Prx1 subfamily.

Redox-sensitive transcriptional activator of soxS; Activates the transcription of the soxS gene which itself controls the superoxide response regulon. SoxR contains a 2Fe-2S iron- sulfur cluster that may act as a redox sensor system that recognizes superoxide. The variable redox state of the Fe-S cluster is employed in vivo to modulate the transcriptional activity of SoxR in response to specific types of oxidative stress. Upon reduction of 2Fe-2S cluster, SoxR reversibly loses its transcriptional activity, but retains its DNA binding affinity.

Superoxide response regulon transcriptional activator; Transcriptional activator of the superoxide response regulon of E.coli that includes at least 10 genes such as sodA, nfo, zwf and micF. Binds the DNA sequence 5'-GCACN(7)CAA-3'. It also facilitates the subsequent binding of RNA polymerase to the micF and the nfo promoters.

Aconitate hydratase 1; Catalyzes the reversible isomerization of citrate to isocitrate via cis-aconitate. The apo form of AcnA functions as a RNA- binding regulatory protein which plays a role as a maintenance or survival enzyme during nutritional or oxidative stress. During oxidative stress inactive AcnA apo-enzyme without iron sulfur clusters binds the acnA mRNA 3' UTRs (untranslated regions), stabilizes acnA mRNA and increases AcnA synthesis, thus mediating a post- transcriptional positive autoregulatory switch. AcnA also enhances the stability of the sodA transcript.

Oxidative and nitrosative stress transcriptional regulator; Hydrogen peroxide sensor. Activates the expression of a regulon of hydrogen peroxide-inducible genes such as katG, gor, ahpC, ahpF, oxyS (a regulatory RNA), dps, fur and grxA. OxyR expression is negatively autoregulated by binding to a 43 bp region upstream of its own coding sequence. OxyR is inactivated by reduction of its essential disulfide bond by the product of GrxA, itself positively regulated by OxyR. Has also a positive regulatory effect on the production of surface proteins that control the colony morphology and auto- [...]

Alkyl hydroperoxide reductase, F52a subunit, FAD/NAD(P)-binding; Serves to protect the cell against DNA damage by alkyl hydroperoxides. It can use either NADH or NADPH as electron donor for direct reduction of redox dyes or of alkyl hydroperoxides when combined with the AhpC protein; Belongs to the class-II pyridine nucleotide-disulfide oxidoreductase family.

Glutathione oxidoreductase; Maintains high levels of reduced glutathione in the cytosol; Belongs to the class-I pyridine nucleotide-disulfide oxidoreductase family.