Laboratoire de Chimie Bactérienne - Institut de Microbiologie de la Méditerranée - IFR 88, UPR 9043 du CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Mol Microbiol. 2011 May;80(3):628-40. doi: 10.1111/j.1365-2958.2011.07611.x. Epub 2011 Mar 21.
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.
NADPH 氧化酶（Phox）产生的氧化爆发是宿主细胞用来消灭吞噬病原体的重要武器。在鼠伤寒沙门氏菌中，先前已提出氧化应激抗性是由致病性岛 2 型 III 型分泌系统（T3SS-2）、周质超氧化物歧化酶和细胞质过氧化物酶/过氧化氢酶介导的。在这里，我们将 OxyR 依赖性启动子与 gfp 融合，构建 ahpC-gfp 转录融合物。该报告基因用于监测沙门氏菌在感染过程中感知到的过氧化氢水平。我们表明，这种融合的表达完全受宿主产生的活性氧控制。在没有细菌周质超氧化物歧化酶或细胞质过氧化物酶/过氧化氢酶的情况下，该融合的表达明显发生了改变。令人惊讶的是，T3SS-2 的失活对 ahpC-gfp 的表达没有影响。所有这些结果表明，沙门氏菌的抗性依赖于其解毒酶的武器库来应对 Phox 介导的氧化应激。
