Aerobic thermoacidophilic archaea belonging to the genus Sulfolobus harbor peroxiredoxins, thiol-dependent peroxidases that assist in protecting the cells from oxidative damage. Here, the crystal structure of the 1-Cys peroxiredoxin from Sulfolobus islandicus, named 1-Cys SiPrx, is presented. A 2.75 Å resolution data set was collected from a crystal belonging to space group P212121, with unit-cell parameters a = 86.8, b = 159.1, c = 189.3 Å, α = β = γ = 90°. The structure was solved by molecular replacement using the homologous Aeropyrum pernix peroxiredoxin (ApPrx) structure as a search model. In the crystal structure, 1-Cys SiPrx assembles into a ring-shaped decamer composed of five homodimers. This quaternary structure corresponds to the oligomeric state of the protein in solution, as observed by size-exclusion chromatography. 1-Cys SiPrx harbors only a single cysteine, which is the peroxidatic cysteine, and lacks both of the cysteines that are highly conserved in the C-terminal arm domain in other archaeal Prx6-subfamily proteins such as ApPrx and that are involved in the association of dimers into higher-molecular-weight decamers and dodecamers. It is thus concluded that the Sulfolobus Prx6-subfamily protein undergoes decamerization independently of arm-domain cysteines.

中文翻译：

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来自 Islandicus 硫化叶菌的 Prx6 亚家族 1-Cys 过氧化还原蛋白的结构。


属于硫化叶菌属的需氧嗜热嗜酸古菌含有过氧化还原蛋白，这是一种硫醇依赖性过氧化物酶，有助于保护细胞免受氧化损伤。这里展示了来自岛硫化叶菌的 1-Cys 过氧化还原蛋白（称为 1-Cys SiPrx）的晶体结构。从属于 P212121 空间群的晶体收集了 2.75 Å 分辨率的数据集，晶胞参数 a = 86.8、b = 159.1、c = 189.3 Å、α = β = γ = 90°。使用同源的Aeropyrum pernix过氧化还原蛋白（ApPrx）结构作为搜索模型，通过分子替换解析了该结构。在晶体结构中，1-Cys SiPrx组装成由五个同型二聚体组成的环形十聚体。这种四级结构对应于溶液中蛋白质的寡聚状态，如通过尺寸排阻色谱法观察到的。 1-Cys SiPrx 仅含有一个半胱氨酸，即过氧化半胱氨酸，并且缺乏在其他古菌 Prx6 亚家族蛋白（例如 ApPrx）的 C 端臂结构域中高度保守且参与关联的两个半胱氨酸二聚体转化为较高分子量的十聚体和十二聚体。因此得出结论，硫化叶菌 Prx6 亚家族蛋白独立于臂域半胱氨酸进行去聚化。