title: Role of rubrerythrin in the oxidative stress response of Porphyromonas gingivalis.
abstract: Rubrerythrins are non-haem iron proteins that have been implicated in oxidative stress protection in anaerobic bacteria and archaea. However, up to now, this role has not been confirmed directly by inactivation of a rubrerythrin gene. Here we report generation of an rbr- mutant of Porphyromonas gingivalis, an obligately anaerobic gingival pathogenic bacterium. Characterization of the rbr- strain clearly showed that P. gingivalis produces a rubrerythrin-like protein that is absent in the rbr- strain, and that the P. gingivalis rbr- strain is more dioxygen- and hydrogen peroxide-sensitive than the wild type. The latter conclusion is based on two independent results, namely, deeper no-growth zones upon diffusion of the oxidants through soft agar culture tubes and growth impairment of liquid cultures exposed to the oxidants. A same-site rbr+ revertant showed increased hydrogen peroxide and dioxygen resistance relative to the rbr- strain. Transcription of the P. gingivalis rubrerythrin gene is induced above its constitutive anaerobic level in response to dioxygen or hydrogen peroxide exposures. Purified rubrerythrins from other organisms have been shown to catalyse reduction of hydrogen peroxide, while showing relatively sluggish reaction with dioxygen and little or no catalase or superoxide dismutase activities. Porphyromonas gingivalis contains a superoxide dismutase but lacks catalase and haem peroxidases. We therefore suggest that rubrerythrin provides oxidative stress protection via catalytic reduction of intracellular hydrogen peroxide.
authors.affiliation: Institute of Molecular Biology, Jagiellonian University, 31-120 Krakow, Poland.
authors.forename: Maryta
authors.initials: M
authors.lastname: Sztukowska
authors.forename: Marcin
authors.initials: M
authors.lastname: Bugno
authors.forename: Jan
authors.initials: J
authors.lastname: Potempa
authors.forename: James
authors.initials: J
authors.lastname: Travis
authors.forename: Donald M
authors.initials: DM
authors.lastname: Kurtz
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D003470:Culture Media; D005288:Ferredoxins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006422:Hemerythrin; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology*; D010544:Peroxidases / Q000378:metabolism; D016133:Polymerase Chain Reaction; D016966:Porphyromonas gingivalis / Q000187:drug effects / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D012416:Rubredoxins
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D005288:Ferredoxins; D006422:Hemerythrin; D011994:Recombinant Proteins; D012416:Rubredoxins; C055857:rubrerythrins; D006861:Hydrogen Peroxide; D010544:Peroxidases