title: Contribution of catalase to hydrogen peroxide resistance in  Enterococcus faecalis.
abstract: Enterococcus faecalis exhibits high resistance to oxidative stress. Several enzymes are responsible for this trait. The role of alkyl hydroperoxide reductase (Ahp), thiol peroxidase (Tpx), and NADH peroxidase (Npr) in oxidative stress defense was recently characterized. Enterococcus faecalis, in contrast to many other streptococci, contains a catalase (KatA), but this enzyme can only be formed when the bacterium is supplied with heme. We have used this heme dependency of catalase activity and mutants deficient in KatA and Npr to investigate the role of the catalase in resistance against exogenous and endogenous hydrogen peroxide stress. The results demonstrate that in the presence of environmental heme catalase contributes to the protection against toxic effects of hydrogen peroxide.
authors.affiliation: Microbiology Group, Department of Biology, Lund University, Lund, Sweden. michael.baureder@biol.lu.se
authors.forename: Michael
authors.initials: M
authors.lastname: Baureder
authors.forename: Ronny
authors.initials: R
authors.lastname: Reimann
authors.forename: Lars
authors.initials: L
authors.lastname: Hederstedt
mesh_terms: D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D024881:Drug Resistance, Bacterial; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D006418:Heme / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D018384:Oxidative Stress / Q000502:physiology*
chemical_list: D003470:Culture Media; D006418:Heme; D006861:Hydrogen Peroxide; D002374:Catalase