Structural Insights into the Dual Activities of the Nerve Agent Degrading Organophosphate Anhydrolase/Prolidase
Structural Insights into the Dual Activities of the Nerve Agent Degrading Organophosphate Anhydrolase/Prolidase
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DOI：
10.1021/bi9011989
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发表时间：
2010-01-26
期刊：
影响因子：
2.9
通讯作者：
Quiocho, Florante A.
中科院分区：
文献类型：
--
作者：
Vyas, Nand K.;Nickitenko, Alexei;Quiocho, Florante A.
有机磷酸脱水酶（OPAA）是一类双金属酶的成员，其水解多种毒性乙酰胆碱酯酶抑制有机磷化合物，包括氟化学神经毒剂。它也属于脯氨酰二肽酶家族，对各种Xaa-Pro二肽具有显著活性。在这里，我们报告了来自交替单胞菌属菌株JD 6.5的天然OPAA（58 kDa质量）及其与抑制剂mipafox [N，N '-二异丙基二氨基氟磷酸盐（DDFP）]的共晶体的X射线结构测定，所述抑制剂是神经毒剂有机磷酸盐底物二异丙基氟磷酸盐（DFP）的密切类似物。OPAA结构由两个结构域组成，氨基和羧基结构域，后者表现出“皮塔饼”结构并具有双核Mn 2+吨的活性位点。天然OPAA结构意外地揭示了活性位点中存在明确的非蛋白质密度，其身份无法明确确定，但提示结合的乙醇酸盐，其与甘氨酸（Xaa）产物具有等排性。所有三个乙醇酸氧与两个Mn 2+原子配位。DDFP或更可能是其水解产物N，N '-二异丙基二酰胺磷酸盐（DDP）存在于共晶结构中，并通过与双核金属配位并与活性位点残基形成氢键和非极性相互作用而结合。两个配体结合的所有不寻常的共同特征是在桥接两个Mn 2+吨中仅涉及乙醇酸羧酸盐和产物DDP四面体磷酸盐的一个氧原子。这两种结构为OPAA的配体识别和氨酰基脯氨酸二肽酶及有机磷水解酶的催化活性提供了新的认识。
The organophosphate acid anhydrolase (OPAA) is a member of a class of bimetalloenzymes that hydrolyze a variety of toxic acetylcholinesterase-inhibiting organophosphorus compounds, including fluorine- chemical nerve agents. It also belongs to a family of prolidases, with significant activity against Various Xaa-Pro dipeptides. Here we report the X-ray Structure determination of the native OPAA (58 kDa mass) from Alteromonas sp. strain JD6.5 and its cocrystal with the inhibitor mipafox [N,N'-diisopropyldiamidofluorophosphate (DDFP)], a close analogue of the nerve agent organophosphate substrate diisopropyl fluorophosphate (DFP). The OPAA Structure is composed of two domains, amino and carboxy domains, with the latter exhibiting a "pita bread" architecture and harboring the active site with the binuclear Mn2+ tons. The native OPAA structure revealed unexpectedly the presence of a well-defined nonproteinaceous density in the active site whose identity could not be definitively established but is suggestive of a bound glycolate, which is isosteric with a glycine (Xaa) product. All three glycolate oxygens coordinate the two Mn2+ atoms. DDFP or more likely its hydrolysis product, N,N'-diisopropyldiamidophosphate (DDP), is present in the cocrystal structure and bound by coordinating the binuclear metals and forming hydrogen bonds and nonpolar interactions with active site residues. Ail Unusual common feature of the binding of the two ligands is the involvement of only one oxygen atom of the glycolate carboxylate and the product DDP tetrahedral phosphate in bridging the two Mn2+ tons. Both Structures provide new understanding of ligand recognition and the prolidase and organophosphorus hydrolase catalytic activities of OPAA.