PDF(Pubmed)
Abstract：
To colonize in the digestive tract of animals and humans, Yersinia pseudotuberculosis has to deal with reactive oxygen species (ROS) produced by host cells and microbiota. However, an understanding of the ROS-scavenging systems and their regulation in this bacterium remains largely elusive. In this study, we identified OxyR as the master transcriptional regulator mediating cellular responses to hydrogen peroxide (H2O2) in Y. pseudotuberculosis through genomics and transcriptomics analyses. OxyR activates transcription of diverse genes, especially the core members of its regulon, including those encoding catalases, peroxidases, and thiol reductases. The data also suggest that sulfur species and manganese may play a particular role in the oxidative stress response of Y. pseudotuberculosis. Among the three H2O2-scavenging systems in Y. pseudotuberculosis, catalase/peroxidase KatE functions as the primary scavenger for high levels of H2O2; NADH peroxidase alkyl hydroperoxide reductase (AhpR) and catalase KatG together are responsible for removing low levels of H2O2. The simultaneous loss of both AhpC (the peroxidatic component of AhpR) and KatG results in activation of OxyR. Moreover, we found that AhpC, unlike its well-characterized Escherichia coli counterpart, has little effect on protecting cells against toxicity of organic peroxides. These findings provide not only novel insights into the structural and functional diversity of bacterial H2O2-scavenging systems but also a basic understanding of how Y. pseudotuberculosis copes with oxidative stress.
摘要：
在动物和人类的消化道中定殖，假结核耶尔森氏菌必须处理宿主细胞和微生物群产生的活性氧（ROS）。然而,对ROS清除系统及其在该细菌中的调节的理解仍然难以捉摸。在这项研究中,通过基因组学和转录组学分析,我们将OxyR确定为介导假结核Y细胞对过氧化氢(H2O2)反应的主要转录调节因子.OxyR激活多种基因的转录，尤其是其条例的核心成员，包括那些编码过氧化氢酶的，过氧化物酶,和硫醇还原酶。数据还表明，硫物种和锰可能在假结核的氧化应激反应中起特殊作用。在Y.假结核的三种H2O2清除系统中，过氧化氢酶/过氧化物酶KatE充当高水平H2O2的主要清除剂；NADH过氧化物酶烷基过氧化氢还原酶（AhpR）和过氧化氢酶KatG一起负责去除低水平的H2O2。AhpC（AhpR的过氧化物成分）和KatG的同时损失导致OxyR的活化。此外，我们发现AHP,不同于其特征明确的大肠杆菌对应物，对保护细胞免受有机过氧化物的毒性影响很小。这些发现不仅提供了对细菌H2O2清除系统的结构和功能多样性的新见解，而且还提供了对Y。假结核如何应对氧化应激的基本理解。
