Salmonella detoxifying enzymes are sufficient to cope with the host oxidative burst

• Published in: Molecular microbiology 2011-05, Vol.80 (3), p.628-640
• Main Authors: Aussel, Laurent, Zhao, Weidong, Hébrard, Magali, Guilhon, Aude‐Agnès, Viala, Julie P. M., Henri, Sandrine, Chasson, Lionel, Gorvel, Jean‐Pierre, Barras, Frédéric, Méresse, Stéphane
• Format: Article
• Language: English
• Subjects: Animals; Artificial Gene Fusion; Bacteriology; Biological and medical sciences; Cells, Cultured; Disease Models, Animal; Enzymes; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Genes, Reporter; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Hydrogen Peroxide - metabolism; Immunology; Inactivation, Metabolic; Life Sciences; Macrophages - microbiology; Mice; Mice, Inbred C57BL; Microbial Viability - drug effects; Microbiology; Miscellaneous; Oxidative stress; Phagosomes - metabolism; Phagosomes - microbiology; Reactive Oxygen Species - metabolism; Respiratory Burst; Salmonella; Salmonella Infections, Animal - immunology; Salmonella Infections, Animal - microbiology; Salmonella typhimurium; Salmonella typhimurium - drug effects; Salmonella typhimurium - physiology; Spleen - microbiology; Superoxides - metabolism
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2011.07611.x

Summary The oxidative burst produced by the NADPH oxidase (Phox) is an essential weapon used by host cells to eradicate engulfed pathogens. In Salmonella typhimurium, oxidative stress resistance has been previously proposed to be mediated by the pathogenicity island 2 type III secretion system (T3SS‐2), periplasmic superoxide dismutases and cytoplasmic catalases/peroxidases. Here, we fused an OxyR‐dependent promoter to the gfp to build the ahpC‐gfp transcriptional fusion. This reporter was used to monitor hydrogen peroxide levels as sensed by Salmonella during the course of an infection. We showed that the expression of this fusion was under the exclusive control of reactive oxygen species produced by the host. The ahpC‐gfp expression was noticeably modified in the absence of bacterial periplasmic superoxide dismutases or cytoplasmic catalases/peroxidases. Surprisingly, inactivation of the T3SS‐2 had no effect on the ahpC‐gfp expression. All together, these results led to a model in which Salmonella resistance relies on its arsenal of detoxifying enzymes to cope with Phox‐mediated oxidative stress.