Crystal structure of a dual activity IMPase/FBPase (AF2372) from Archaeoglobus fulgidus -: The story of a mobile loop
Crystal structure of a dual activity IMPase/FBPase (AF2372) from Archaeoglobus fulgidus -: The story of a mobile loop
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DOI：
10.1074/jbc.m201042200
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发表时间：
2002-06-21
影响因子：
4.8
通讯作者：
Stec, B
中科院分区：
文献类型：
--
作者：
Stieglitz, KA;Johnson, KA;Stec, B
几种超嗜热生物体含有一种不寻常的磷酸酶，该酶对肌醇单磷酸和果糖 1,6-二磷酸具有双重活性。该家族的第二个成员，来自古生球菌 (Archaeoglobus fulgidus) (AF2372) 的 FBPase/IMPase 的结构已被解析。这种酶与之前解决的詹氏甲烷球菌 (MJ0109) 的酶在动力学和结构上有许多相似之处。它还显示出二价金属离子结合的一些动力学差异以及与热稳定性下降相关的二聚体界面的结构变化。不同晶体形式的可用性使我们能够研究配体的存在对独立于晶体堆积的移动催化环的构象的影响。 AF2372 中的这种构象变异性与该结构家族中对亚毫摩尔浓度的 Li+ 敏感或不敏感的其他成员中观察到的构象变异性进行了比较。该分析为先前提出的涉及三种金属离子的催化机制提供了支持。环构象与 Li+ 抑制强度的直接相关性为该酶的扩展家族提供了有用的分类系统。
Several hyperthermophilic organisms contain an unusual phosphatase that has dual activity toward inositol monophosphates and fructose 1,6-bisphosphate. The structure of the second member of this family, an FBPase/IMPase from Archaeoglobus fulgidus (AF2372), has been solved. This enzyme shares many kinetic and structural similarities with that of a previously solved enzyme from Methanococcus jannaschii (MJ0109). It also shows some kinetic differences in divalent metal ion binding as well as structural variations at the dimer interface that correlate with decreased thermal stability. The availability of different crystal forms allowed us to investigate the effect of the presence of ligands on the conformation of a mobile catalytic loop independently of the crystal packing. This conformational variability in AF2372 is compared with that observed in other members of this structural family that are sensitive or insensitive to submillimolar concentrations of Li+. This analysis provides support for the previously proposed mechanism of catalysis involving three metal ions. A direct correlation of the loop conformation with strength of Li+ inhibition provides a useful system of classification for this extended family of enzymes.