School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, India.
Division of Microbiology, Central Drug Research Institute, Lucknow, India.
Appl Environ Microbiol. 2018 Nov 15;84(23). doi: 10.1128/AEM.01787-18. Print 2018 Dec 1.
The genome of encodes five RpoH sigma factors: two OxyR transcription regulators and three catalases. The aim of this study was to understand the role they play during oxidative stress and their regulatory interconnection. Out of the 5 paralogs of RpoH present in , inactivation of only renders heat sensitive. While transcript levels of were elevated by heat stress, those of and were upregulated by HO Catalase activity was upregulated in and its :: mutants in response to HO except in the case of the :: mutant, suggesting a role for RpoH5 in regulating inducible catalase. Transcriptional analysis of the , I, and II genes revealed that the expression of and II was severely compromised in the :: and :: mutants, respectively. Regulation of and II by RpoH3 and RpoH5, respectively, was further confirmed in an two-plasmid system. Regulation of II by OxyR2 was evident by a drastic reduction in growth, KatAII activity, and II:: expression in an :: mutant. This study reports the involvement of RpoH3 and RpoH5 sigma factors in regulating oxidative stress response in alphaproteobacteria. We also report the regulation of an inducible catalase by a cascade of alternative sigma factors and an OxyR. Out of the three catalases in , those corresponding to and II are regulated by RpoH3 and RpoH5, respectively. The expression of II is regulated by a cascade of RpoE1→RpoH5 and OxyR2. analysis of the genome showed the presence of multiple paralogs of genes involved in oxidative stress response, which included 2 OxyR transcription regulators and 3 catalases. So far, and are known to harbor two paralogs of OxyR, and harbors three catalases. We do not yet know how the expression of multiple catalases is regulated in any bacterium. Here we show the role of multiple RpoH sigma factors and OxyR in regulating the expression of multiple catalases in Sp7. Our work gives a glimpse of systems biology of used for responding to oxidative stress.
编码五个 RpoH sigma 因子：两个 OxyR 转录调节因子和三个过氧化氢酶。本研究的目的是了解它们在氧化应激过程中的作用及其调控的相互联系。在 Sp7 中，有 5 个 RpoH 旁系同源物，只有缺失时才使 Sp7 对热敏感。虽然热应激导致转录水平升高，但 和 的转录水平上调是由 HO 过氧化氢酶活性上调引起的，除了 :: 突变体外，这表明 RpoH5 在调节诱导型过氧化氢酶方面发挥作用。对 Sp7 的 、I 和 II 基因的转录分析表明，和 II 的表达分别在 :: 和 :: 突变体中严重受损。在一个双质粒系统中，进一步证实了 RpoH3 和 RpoH5 分别调节 和 II 的转录。OxyR2 对 II 的调节作用明显，在 :: 突变体中，生长、KatAII 活性和 II:: 表达明显降低。本研究报告了 RpoH3 和 RpoH5 sigma 因子参与调控α变形菌的氧化应激反应。我们还报告了一个由替代 sigma 因子和 OxyR 组成的级联反应调节一种诱导型过氧化氢酶。在 Sp7 中的三种过氧化氢酶中，对应于 和 II 的过氧化氢酶分别由 RpoH3 和 RpoH5 调节。II 的表达受 RpoE1→RpoH5 和 OxyR2 级联反应的调节。对 Sp7 基因组的分析显示，参与氧化应激反应的基因有多个人类拷贝，包括 2 个 OxyR 转录调节因子和 3 个过氧化氢酶。到目前为止，已经知道 和 含有两个 OxyR 旁系同源物，而 含有三个过氧化氢酶。我们还不知道在任何细菌中如何调节多个过氧化氢酶的表达。在这里，我们展示了多个 RpoH sigma 因子和 OxyR 在调节 Sp7 中多个过氧化氢酶表达中的作用。我们的工作为用于应对氧化应激的 Sp7 系统生物学提供了一个视角。
