Radiation Research Division, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea; Department of Biotechnology and Bioengineering, Interdisciplinary Program for Bioenergy and Biomaterials, Chonnam National University, Gwangju, 61186, Republic of Korea.
Radiation Research Division, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea.
Biochem Biophys Res Commun. 2020 Aug 20;529(2):444-449. doi: 10.1016/j.bbrc.2020.06.061. Epub 2020 Jul 1.
Deinococcus radiodurans is well known for its extreme resistance to ionizing radiation (IR). Since reactive oxygen species generated by IR can damage various cellular components, D. radiodurans has developed effective antioxidant systems to cope with this oxidative stress. dr1765 from D. radiodurans is predicted to encode an alkyl hydroperoxidase-like protein (AhpD family), which is implicated in the reduction of hydrogen peroxide (HO) and organic hydroperoxides. In this study, we constructed a dr1765 mutant strain (Δdr1765) and examined the survival rate after HO treatment. Δdr1765 showed a significant decrease in the HO resistance compared to the wild-type strain. We also determined the crystal structure of DR1765 at 2.27 Å resolution. DR1765 adopted an all alpha helix protein fold representative of the AhpD-like superfamily. Structural comparisons of DR1765 with its structural homologues revealed that DR1765 possesses the Glu74-Cys86-Tyr88-Cys89-His93 signature motif, which is conserved in the proton relay system of AhpD. Complementation of Δdr1765 with dr1765 encoding C86A or C89A mutation failed to restore the survival rate to wild-type level. Taken together, these results suggest that DR1765 might function as an AhpD to protect cells from oxidative stress.
耐辐射球菌以其对电离辐射（IR）的极强抗性而闻名。由于 IR 产生的活性氧物种会破坏各种细胞成分，耐辐射球菌已经开发出有效的抗氧化系统来应对这种氧化应激。耐辐射球菌的 dr1765 预测编码一种烷基过氧化物酶样蛋白（AhpD 家族），该蛋白参与过氧化氢（HO）和有机过氧化物的还原。在这项研究中，我们构建了 dr1765 突变菌株（Δdr1765），并检查了 HO 处理后的存活率。与野生型菌株相比，Δdr1765 的 HO 抗性明显下降。我们还确定了 DR1765 在 2.27Å分辨率下的晶体结构。DR1765 采用了全α螺旋蛋白折叠，代表了 AhpD 样超家族。DR1765 与其结构同源物的结构比较表明，DR1765 具有 Glu74-Cys86-Tyr88-Cys89-His93 特征基序，该基序在 AhpD 的质子传递系统中保守。用编码 C86A 或 C89A 突变的 dr1765 对 Δdr1765 的互补未能将存活率恢复到野生型水平。综上所述，这些结果表明 DR1765 可能作为 AhpD 发挥作用，保护细胞免受氧化应激。
