Structural and functional characterization of the Pseudomonas hydroperoxide resistance protein Ohr
Structural and functional characterization of the Pseudomonas hydroperoxide resistance protein Ohr
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DOI：
10.1093/emboj/cdf670
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发表时间：
2002-12-16
期刊：
影响因子：
11.4
通讯作者：
Nikolov, DB
中科院分区：
文献类型：
--
作者：
Lesniak, J;Barton, WA;Nikolov, DB
细菌已经开发出复杂的策略来解毒和修复由活性氧引起的损伤。这些化合物在细菌需氧呼吸过程中以及由宿主免疫系统细胞作为抵抗病原微生物的防御机制产生，具有破坏核酸、蛋白质和磷脂膜的能力。在这里，我们描述了铜绿假单胞菌Ohr，最近发现的有机氢过氧化物抗性蛋白家族的成员的晶体结构。Ohr是一种紧密折叠的同二聚体，具有新颖的α/β折叠，并且包含位于分子相对侧上的单体界面处的两个活性位点。使用体外试验，我们证明OHR直接作为氢过氧化物还原酶，将无机和有机氢过氧化物转化为毒性较小的代谢产物。定点突变证实，在每个活性位点的两个保守的半胱氨酸是必不可少的催化活性。我们建议，OHR的催化机制是类似的结构无关的peroxiredoxins，直接利用高活性的半胱氨酸巯基引发氢过氧化物还原。
Bacteria have developed complex strategies to detoxify and repair damage caused by reactive oxygen species. These compounds, produced during bacterial aerobic respiration as well as by the host immune system cells as a defense mechanism against the pathogenic microorganisms, have the ability to damage nucleic acids, proteins and phospholipid membranes. Here we describe the crystal structure of Pseudomonas aeruginosa Ohr, a member of a recently discovered family of organic hydroperoxide resistance proteins. Ohr is a tightly folded homodimer, with a novel alpha/beta fold, and contains two active sites located at the monomer interface on opposite sides of the molecule. Using in vitro assays, we demonstrate that Ohr functions directly as a hydroperoxide reductase, converting both inorganic and organic hydroperoxides to less toxic metabolites. Site-directed mutagenesis confirms that the two conserved cysteines in each active site are essential for catalytic activity. We propose that the Ohr catalytic mechanism is similar to that of the structurally unrelated peroxiredoxins, directly utilizing highly reactive cysteine thiol groups to elicit hydroperoxide reduction.