title: Comparative analysis of the responses of related pathogenic and environmental bacteria to oxidative stress.
abstract: Bacillus anthracis, the causative agent of anthrax, is exposed to host-mediated antibacterial activities, such as reactive oxygen species (ROS), during the early stages of its disease process. The ability to resist these host-mediated stresses is an essential characteristic of a successful pathogen while it is generally assumed that non-pathogenic environmental bacteria succumb to these antimicrobial activities. In order to gain insights into the underlying mechanisms that pathogens use to resist host-mediated oxidative stress, we have compared the oxidative stress responses of B. anthracis and Bacillus subtilis, a well-studied environmental bacterium. Among the four putative catalases encoded by B. anthracis we identified KatB as the main vegetative catalase. Comparative analysis of catalase production in B. anthracis and B. subtilis in response to superoxide and peroxide stress reveals different expression profiles, even though both are regulated by the PerR repressor, which senses and responds to peroxide stress. A B. anthracis perR deletion mutant exhibits enhanced KatB activity and is hyper-resistant to peroxide stress. Superoxide dismutase A1 (SodA1) is the main contributor to the intracellular superoxide dismutase activity in vegetative cells and the gene encoding this enzyme is constitutively expressed. Although aspects of the ROS detoxifying systems of B. anthracis and B. subtilis are similar, their responses to superoxide stress are different. The observed differences are likely to reflect adaptations to specific environmental niches.
authors.affiliation: Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Wang Yung
authors.initials: WY
authors.lastname: Tu
authors.affiliation: Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Susanne
authors.initials: S
authors.lastname: Pohl
authors.affiliation: Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Pijug
authors.initials: P
authors.lastname: Summpunn
authors.affiliation: Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Silvio
authors.initials: S
authors.lastname: Hering
authors.affiliation: Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Sandra
authors.initials: S
authors.lastname: Kerstan
authors.affiliation: Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Harwood
mesh_terms: D001408:Bacillus anthracis / Q000187:drug effects* / Q000502:physiology*; D001412:Bacillus subtilis / Q000187:drug effects* / Q000502:physiology*; D002374:Catalase / Q000096:biosynthesis; D020869:Gene Expression Profiling; D018384:Oxidative Stress; D010545:Peroxides / Q000633:toxicity; D013312:Stress, Physiological; D013482:Superoxide Dismutase / Q000096:biosynthesis
chemical_list: D010545:Peroxides; D002374:Catalase; D013482:Superoxide Dismutase