Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, North Carolina, USA.
J Bacteriol. 2012 Sep;194(18):5065-72. doi: 10.1128/JB.00873-12. Epub 2012 Jul 20.
The organic hydroperoxide resistance protein Ohr has been identified in numerous bacteria where it functions in the detoxification of organic hydroperoxides, and expression of ohr is often regulated by a MarR-type regulator called OhrR. The genes annotated as BAB2_0350 and BAB2_0351 in the Brucella abortus 2308 genome sequence are predicted to encode OhrR and Ohr orthologs, respectively. Using isogenic ohr and ohrR mutants and lacZ promoter fusions, it was determined that Ohr contributes to resistance to organic hydroperoxide, but not hydrogen peroxide, in B. abortus 2308 and that OhrR represses the transcription of both ohr and ohrR in this strain. Moreover, electrophoretic mobility shift assays and DNase I footprinting revealed that OhrR binds directly to a specific region in the intergenic region between ohr and ohrR that shares extensive nucleotide sequence similarity with so-called "OhrR boxes" described in other bacteria. While Ohr plays a prominent role in protecting B. abortus 2308 from organic hydroperoxide stress in in vitro assays, this protein is not required for the wild-type virulence of this strain in cultured murine macrophages or experimentally infected mice.
有机过氧化物抗性蛋白 Ohr 已在许多细菌中被鉴定出来，在这些细菌中，它在有机过氧化物的解毒中发挥作用，并且 ohr 的表达通常受到一种称为 OhrR 的 MarR 型调节剂的调节。布鲁氏菌 2308 基因组序列中注释为 BAB2_0350 和 BAB2_0351 的基因预计分别编码 OhrR 和 Ohr 同源物。使用同源 ohr 和 ohrR 突变体和 lacZ 启动子融合，确定 Ohr 有助于布鲁氏菌 2308 抵抗有机过氧化物，但不抵抗过氧化氢，并且 OhrR 在该菌株中抑制 ohr 和 ohrR 的转录。此外，电泳迁移率变动分析和 DNase I 足迹分析表明，OhrR 直接结合 ohr 和 ohrR 之间的基因间区域的特定区域，该区域与其他细菌中描述的所谓“OhrR 盒”具有广泛的核苷酸序列相似性。虽然 Ohr 在体外试验中在保护布鲁氏菌 2308 免受有机过氧化物应激方面发挥着重要作用，但这种蛋白质对于该菌株在培养的鼠巨噬细胞或实验感染的小鼠中的野生型毒力并非必需。
