Gene Regulation by Redox-Sensitive Burkholderia thailandensis OhrR and Its Role in Bacterial Killing of Caenorhabditis elegans
Gene Regulation by Redox-Sensitive Burkholderia thailandensis OhrR and Its Role in Bacterial Killing of Caenorhabditis elegans
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DOI：
10.1128/iai.00322-18
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发表时间：
2018-09-01
影响因子：
3.1
通讯作者：
Grove, Anne
中科院分区：
文献类型：
--
作者：
Pande, Anuja;Veale, Todd C.;Grove, Anne
脂肪酸氢过氧化物参与宿主-病原体相互作用。在植物和哺乳动物中，多不饱和脂肪酸在感染期间被释放，并在旨在阻止感染的防御性氧化爆发期间被酶氧化为相应的有毒氢过氧化物。细菌转录因子OhrR（有机氢过氧化物还原酶调节剂）被有机氢过氧化物氧化，从而诱导编码有机氢过氧化物还原酶的ohr基因。这种酶将氢过氧化物转化为毒性较小的醇。我们发现来自泰国伯克霍尔德菌的OhrR抑制ohr的表达。过氧化异丙苯可诱导基因表达，无机氧化剂的诱导程度较低；然而，Ohr只对有机过氧化氢有降解作用。泰国芽胞杆菌OhrR结合了ohr和OhrR启动子中的特定位点，属于OhrR蛋白的2-Cys亚家族，其氧化导致在不同单体中保守的N端和c端半胱氨酸之间形成可逆的二硫键。在体外，n端Cys的氧化足以减弱DNA结合，添加还原剂后DNA结合完全恢复。令人惊讶的是，ohr的过表达和ohr的缺失都能提高体外暴露于有机过氧化氢的存活率。虽然ahr细胞在秀丽隐杆线虫感染模型中毒性更强，但Delta ohrR细胞的毒性较弱。综上所述，我们的数据表明泰国芽孢杆菌OhrR具有几个非常规的特征，并且OhrR和有机氢过氧化物都可能有助于毒性。
Fatty acid hydroperoxides are involved in host-pathogen interactions. In both plants and mammals, polyunsaturated fatty acids are liberated during infection and enzymatically oxidized to the corresponding toxic hydroperoxides during the defensive oxidative burst that is designed to thwart the infection. The bacterial transcription factor OhrR (organic hydroperoxide reductase regulator) is oxidized by organic hydroperoxides, as a result of which the ohr gene encoding organic hydroperoxide reductase is induced. This enzyme converts the hydroperoxides to less toxic alcohols. We show here that OhrR from Burkholderia thailandensis represses expression of ohr. Gene expression is induced by cumene hydroperoxide and to a lesser extent by inorganic oxidants; however, Ohr contributes to degradation only of the organic hydroperoxide. B. thailandensis OhrR, which binds specific sites in both ohr and ohrR promoters, as evidenced by DNase I footprinting, belongs to the 2-Cys subfamily of OhrR proteins, and its oxidation leads to reversible disulfide bond formation between conserved N- and C-terminal cysteines in separate monomers. Oxidation of the N-terminal Cys is sufficient for attenuation of DNA binding in vitro, with complete restoration of DNA binding occurring on addition of a reducing agent. Surprisingly, both overexpression of ohr and deletion of ohr results in enhanced survival on exposure to organic hydroperoxide in vitro. While Aohr cells are more virulent in a Caenorhabditis elegans model of infection, Delta ohrR cells are less so. Taken together, our data suggest that B. thailandensis OhrR has several unconventional features and that both OhrR and organic hydroperoxides may contribute to virulence.