Lookup NU author(s): Dr Susanne Pohl,
Professor Colin Harwood
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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 insults 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 B. 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 that 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 specific environmental niches.
Author(s): Tu WY, Pohl S, Summpunn P, Hering S, Kerstan S, Harwood CR
Publication type: Article
ISSN (print): 1350-0872
ISSN (electronic): 1465-2080
Publisher: Society for General Microbiology
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