摘要: 渗透胁迫诱导蛋白 OsmC 与有机氢过氧化物抗性蛋白 Ohr 都属于 OsmC 超家族抗氧化物酶，在细菌抵御有机或无机过氧化反应的过程中起重要作用。 耐辐射异常球菌 ( D. radiodurans R1 ) 中 osmC 基因 ( DR_ 1538) 与 ohr 基因 ( DR_ 1857) 分别编码了 OsmC 超家族中的这两种抗氧化物酶。运用体外三段融合 PCR 方法和线性转化方法，首次构建了壮观霉素抗性完全缺失突变株 Δ osmC 和卡那霉素抗性完全缺失突变株 Δ oh r 。 对 Δ osmC 、 Δ ohr 突变株 和野生型菌株分别都进行 CHP( 异丙苯基过氧化氢 ) 、 H ₂ O ₂ 和 NaCl 胁迫处理，结果显示，与野生型相比， Δ osmC 突变株对 H₂O₂ 异常敏感，而 Δ ohr 突变株 对 CHP 更敏感，两个突变株对 NaCl 胁迫都没有大的变化。 QRT-PCR 结果显示在 H₂O₂ 和 NaCl 胁迫下野生型菌株中 osmC 基因都上调，其中 H₂O₂ 胁迫下基因上调水平显著；在 CHP 和 NaCl 胁迫下野生型菌株中 ohr 基因基因上调大约 2 倍左右。根据结果推测同属于 OsmC 超家族的两个过氧化物酶选择底物的偏好性与作用方式可能并不一样， OsmC 蛋白可能主要是以 无机过氧化物 作为底物，而 Ohr 蛋白可能主要是以有机过氧化物为底物。 The osmotic stress induced protein (OsmC) and organic hydroperoxide resistance protein (Ohr) were two antioxidant enzymes which play an important role in bacteria defensing organic or inorganic peroxidation. The osmC gene ( DR_ 1538) and ohr gene ( DR_ 1857) of Deinococcus radiodurans ( D. radiodurans R1) encoded the two antioxidant enzymes in the OsmC superfamily. Fusion PCR of three sections in vitro and linear transformation method were used to firstly construct the spectinomycin-resistant mutant stain (Δ osmC ) and the kanamycin-resistant mutant strain (Δ ohr ). The Δ osmC , Δ ohr mutants strain and wild-type strain were treated with CHP (cumene hydroperoxide),H₂O₂ and NaCl stress treatments. The result showed that Δ osmC mutant is extremely sensitive toH₂O₂ compared with the wild type, while Δ ohr mutant is more sensitive to CHP and the two mutant strains had no changes after NaCl stress. QRT-PCR results displayed that the osmC gene of the wild-type strain were up-regulated in bothH₂O₂ and NaCl stress treatments, and the osmC gene inH₂O₂ stress levels was significantly upregulated. The ohr genes in wild-type strain after CHP and NaCl stress treatments upregulated approximately 2-folds. From above, it was presumed that there may be different at the preference of two peroxidases in OsmC superfamily selecting substrates and the mode of those interacting with their substrate; OsmC proteins may mainly use inorganic peroxide as its substrate and Ohr protein may be primarily based on the organic peroxide as its substrate.