The crystal structure of the hydrolase domain of 10-formyltetrahydrofolate dehydrogenase - Mechanism of hydrolysis and its interplay with the dehydrogenase domain
The crystal structure of the hydrolase domain of 10-formyltetrahydrofolate dehydrogenase - Mechanism of hydrolysis and its interplay with the dehydrogenase domain
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DOI：
10.1074/jbc.m313934200
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发表时间：
2004-04-02
影响因子：
4.8
通讯作者：
Davies, C
中科院分区：
文献类型：
--
作者：
Chumanevich, AA;Krupenko, SA;Davies, C
10-甲酰基四氢叶酸脱氢酶(FDH)将核苷酸生物合成的前体10-甲酰基四氢叶酸转化为四氢叶酸。该蛋白质包括两个功能结构域：一个是从10-甲酰基四氢叶酸中去除甲酰基的水解酶结构域，另一个是依赖于NADP(+)的脱氢酶结构域，它将甲酰还原为二氧化碳。作为破译该酶催化机制的第一步，我们测定了大鼠FDH水解酶结构域的晶体结构，分辨率为2.3埃。该结构包括两个域。不出所料，结构域1与相关酶甲硫酰-tRNA-甲酰基转移酶和甘氨酰胺核苷酸甲酰基转移酶具有相同的Rossmann折叠，但出人意料的是，10-甲酰基四氢叶酸脱氢酶和甲硫酰-tRNA-甲酰基转移酶氨基末端的结构相似性延伸到了这两种蛋白的C端。活性部位含有一个位于His-106和Asp-142之间的β-巯基乙醇分子，似乎模仿甲酸盐产物。提出了Asp-142极化催化水分子，His-106定向甲酰基的水解酶反应机理。该结构还提供了关于在天然酶中，水解酶结构域如何将其产物转移到脱氢酶结构域的线索。
10-Formyltetrahydrofolate dehydrogenase (FDH) converts 10-formyltetrahydrofolate, a precursor for nucleotide biosynthesis, to tetrahydrofolate. The protein comprises two functional domains: a hydrolase domain that removes a formyl group from 10-formyltetrahydrofolate and a NADP(+)-dependent dehydrogenase domain that reduces the formyl to carbon dioxide. As a first step toward deciphering the catalytic mechanism of the enzyme, we have determined the crystal structure of the hydrolase domain of FDH from rat, solved to 2.3-Angstrom resolution. The structure comprises two domains. As expected, domain 1 shares the same Rossmann fold as the related enzymes, methionyl-tRNA-formyltransferase and glycinamide ribonucleotide formyltransferase, but, unexpectedly, the structural similarity between the amino-terminal domain of 10-formyltetrahydrofolate dehydrogenase and methionyl-tRNA-formyltransferase extends to the C terminus of both proteins. The active site contains a molecule of beta-mercaptoethanol that is positioned between His-106 and Asp-142 and that appears to mimic the formate product. We propose a catalytic mechanism for the hydrolase reaction in which Asp-142 polarizes the catalytic water molecule and His-106 orients the carbonyl group of formyl. The structure also provides clues as to how, in the native enzyme, the hydrolase domain transfers its product to the dehydrogenase domain.