Peroxiredoxin Systems

Volume 44 of the series Subcellular Biochemistry pp 143-193

Peroxiredoxins in Bacterial Antioxidant Defense

  • James M. DubbsAffiliated withLaboratory of Biotechnology, Chulabhorn Research Institute
  • , Skorn MongkolsukAffiliated withLaboratory of Biotechnology, Chulabhorn Research InstituteDepartment of Biotechnology,Faculty of Science, Mahidol University

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Peroxiredoxins constitute an important component of the bacterial defense against toxic peroxides. These enzymes use reactive cysteine thiols to reduce peroxides with electrons ultimately derived from reduced pyridine dinucleotides. Studies examining the regulation and physiological roles of AhpC, Tpx, Ohr and OsmC reveal the multi-layered nature of bacterial peroxide defense. AhpC is localized in the cytoplasm and has a wide substrate range that includesH2O2, organic peroxides and peroxynitrite. This enzyme functions in both the control of endogenous peroxides, as well as in the inducible defense response to exogenous peroxides or general stresses. Ohr, OsmC and Tpx are organic peroxide specific. Tpx is localized to the periplasm and can be involved in either constitutive peroxide defense or participate in oxidative stress inducible responses depending on the organism. Ohr is an organic peroxide specific defense system that is under the control of the organic peroxide sensing repressor OhrR. In some organisms Ohr homologs are regulated in response to general stress. Clear evidence indicates that AhpC, Tpx and Ohr are involved in virulence. The role of OsmC is less clear. Regulation of OsmC expression is not oxidative stress inducible, but is controlled by multiple general stress responsive regulators

Peroxiredoxin Oxidative stress Gene regulation Ohr OsmC AhpC Tpx OhrR OxyR PerR HypR Organic peroxide Hydrogen peroxide Peroxynitrite Bacteria Virulence