Crystal structure of monofunctional histidinol phosphate phosphatase from Thermus thermophilus HB8
Crystal structure of monofunctional histidinol phosphate phosphatase from Thermus thermophilus HB8
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DOI：
10.1021/bi701204r
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发表时间：
2007-11-06
期刊：
影响因子：
2.9
通讯作者：
Hirotsu, Ken
中科院分区：
文献类型：
--
作者：
Omi, Ric;Goto, Masaru;Hirotsu, Ken
来自嗜热热菌（Thermus thermophilus） HB8的单功能组氨酸二醇磷酸磷酸酶，催化l -组氨酸二醇磷酸去磷酸化，与细菌DNA聚合酶III和X家族DNA聚合酶的PHP结构域一起属于PHP家族。我们分别在1.6、2.1和1.8 a的分辨率下确定了硫酸盐离子配合物、磷酸盐离子配合物和非配体形式的结构。该酶以四聚体形式存在，其亚基由一个扭曲的W(X)7桶状结构组成，带有一个连接体和一个c末端尾部。位于桶体c端侧的三个金属位分别被Fe1、Fe2和Zn离子占据，形成由7个组氨酸、1个天冬氨酸、1个谷氨酸和1个氢氧化物配位的三核金属中心，两个铁离子被氢氧化物桥接。在配合物中，硫酸盐离子或磷酸盐离子与三个金属离子配位，分别在Fe1、Fe2和Zn离子周围形成八面体、三角双锥体和四面体几何形状。配体残基来源于PHP家族的四个基序和两个在组氨酸二醇磷酸磷酸酶中保守的基序。0007筒体和金属团簇在性质和结构上分别与氨基水解酶超家族中的（808）筒体和单核或双核金属中心密切相关。磷酸盐离子对金属中心的配位行为支持了桥接氢氧化物直接攻击与两个铁离子和锌离子三叉键结合的底物磷酸盐水解磷酸酯键的机制。
Monufunctional histidinol phosphate phosphatase from Thermus thermophilus HB8, which catalyzes the dephosphorylation Of L-histidinol phosphate, belongs to the PHP family, together with the PHP domain of bacterial DNA polymerase III and family X DNA polymerase. We have determined the structures of the complex with a sulfate ion, the complex with a phosphate ion, and the unliganded form at 1.6, 2.1, and 1.8 A resolution, respectively. The enzyme exists as a tetramer, and the subunit consists of a distorted W(X)7 barrel with one linker and one C-terminal tail. Three metal sites located on the C-terminal side of the barrel are occupied by Fe1, Fe2, and Zn ions, respectively, forming a trinuclear metal center liganded by seven histidines, one aspartate, one glutamate, and one hydroxide with two Fe ions bridged by the hydroxide. In the complexes, the sulfate or phosphate ion is coordinated to three metal ions, resulting in octahedral, trigonal bipyramidal, and tetrahedral geometries around the Fe1, Fe2, and Zn ions, respectively. The ligand residues are derived from the four motifs that characterize the PHP family and from two motifs conserved in histidinol phosphate phosphatases. The 0007 barrel and the metal cluster are closely related in nature and architecture to the (,808 barrel and the mononuclear or dinuclear metal center in the amidohydrolase superfamily, respectively. The coordination behavior of the phosphate ion toward the metal center supports the mechanism in which the bridging hydroxide makes a direct attack on the substrate phosphate tridentately bound to the two Fe ions and Zn ion to hydrolyze the phosphoester bond.