1 Institute for Biology-Microbiology, Freie Universität Berlin , Berlin, Germany .
2 Center for Biotechnology, Bielefeld University , Bielefeld, Germany .
Antioxid Redox Signal. 2018 Sep 1;29(7):615-636. doi: 10.1089/ars.2017.7354. Epub 2018 Jan 30.
Staphylococcus aureus is a major human pathogen and has to cope with reactive oxygen and chlorine species (ROS, RCS) during infections, which requires efficient protection mechanisms to avoid destruction. Here, we have investigated the changes in the RNA-seq transcriptome by the strong oxidant sodium hypochlorite (NaOCl) in S. aureus USA300 to identify novel redox-sensing mechanisms that provide protection under infection conditions.
NaOCl stress caused an oxidative stress response in S. aureus as indicated by the induction of the PerR, QsrR, HrcA, and SigmaB regulons in the RNA-seq transcriptome. The hypR-merA (USA300HOU_0588-87) operon was most strongly upregulated under NaOCl stress, which encodes for the Rrf2-family regulator HypR and the pyridine nucleotide disulfide reductase MerA. We have characterized HypR as a novel redox-sensitive repressor that controls MerA expression and directly senses and responds to NaOCl and diamide stress via a thiol-based mechanism in S. aureus. Mutational analysis identified Cys33 and the conserved Cys99 as essential for NaOCl sensing, while Cys99 is also important for repressor activity of HypR in vivo. The redox-sensing mechanism of HypR involves Cys33-Cys99 intersubunit disulfide formation by NaOCl stress both in vitro and in vivo. Moreover, the HypR-controlled flavin disulfide reductase MerA was shown to protect S. aureus against NaOCl stress and increased survival in J774A.1 macrophage infection assays. Conclusion and Innovation: Here, we identified a new member of the widespread Rrf2 family as redox sensor of NaOCl stress in S. aureus that uses a thiol/disulfide switch to regulate defense mechanisms against the oxidative burst under infections in S. aureus. Antioxid. Redox Signal. 29, 615-636.
金黄色葡萄球菌是一种主要的人类病原体，在感染过程中必须应对活性氧和氯物种（ROS、RCS），这需要有效的保护机制来避免破坏。在这里，我们研究了强氧化剂次氯酸钠（NaOCl）在 USA300 金黄色葡萄球菌中的 RNA-seq 转录组变化，以确定新的氧化还原感应机制，为感染条件下提供保护。
NaOCl 应激导致金黄色葡萄球菌发生氧化应激反应，这表现在 RNA-seq 转录组中诱导了 PerR、QsrR、HrcA 和 SigmaB 调控子。在 NaOCl 应激下，hypR-merA（USA300HOU_0588-87）操纵子被强烈上调，该操纵子编码 Rrf2 家族调控因子 HypR 和吡啶核苷酸二硫化物还原酶 MerA。我们将 HypR 表征为一种新的氧化还原敏感的阻遏物，它控制 MerA 的表达，并通过金黄色葡萄球菌中的基于硫醇的机制直接感应和响应 NaOCl 和双脒基化合物应激。突变分析确定 Cys33 和保守的 Cys99 对于 NaOCl 感应至关重要，而 Cys99 对于 HypR 在体内的阻遏活性也很重要。HypR 的氧化还原感应机制涉及 Cys33-Cys99 亚基间二硫键的形成，这是由 NaOCl 应激引起的，无论是在体外还是在体内。此外，HypR 控制的黄素二硫化物还原酶 MerA 被证明可以保护金黄色葡萄球菌免受 NaOCl 应激，并增加 J774A.1 巨噬细胞感染试验中的存活。结论和创新：在这里，我们确定了 Rrf2 家族的一个新成员是金黄色葡萄球菌中 NaOCl 应激的氧化还原传感器，它使用硫醇/二硫键开关来调节金黄色葡萄球菌感染过程中针对氧化爆发的防御机制。抗氧化。氧化还原信号。29，615-636。
