Structural basis of substrate specificity in human glyoxylate reductase/hydroxypyruvate reductase
Structural basis of substrate specificity in human glyoxylate reductase/hydroxypyruvate reductase
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DOI：
10.1016/j.jmb.2006.05.018
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发表时间：
2006-06-30
影响因子：
5.6
通讯作者：
Brady, R. Leo
中科院分区：
文献类型：
--
作者：
Booth, Michael P. S.;Conners, R.;Brady, R. Leo
人乙醛酸还原酶/羟基丙酮酸还原酶 (GRHPR) 是一种 D-，在清除肝脏内代谢副产物乙醛酸方面发挥着关键作用。这种酶的缺乏是原发性高草酸尿症的根本原因。 2 型 (PH2) 会导致尿草酸盐水平升高、肾结石形成和肾功能衰竭。在这里，我们以 2.2 埃分辨率描述了人类 GRHPR 的晶体结构。晶体学不对称单元中有四个GRHPR拷贝：在每个同型二聚体中，一个亚基形成三元（酶+NADPH+还原底物）复合物，另一个亚基形成二元（酶+NADPH）形式。两个酶结构域的空间排列在二元和三元形式中是相同的。该家族酶的真正三元复合物的第一个晶体结构证明了活性位点内底物和催化残基的关系，证实了这些酶的底物结合模式、立体特异性和可能的催化机制的早期建议。 GRHPR 具有不寻常的底物特异性，更喜欢乙醛酸和羟基丙酮酸，但不喜欢丙酮酸。来自二聚体相邻亚基的色氨酸残基 (Trp141) 投射到活性位点区域，似乎有助于羟基丙酮酸的选择性。人类 GRHPR 酶的第一个晶体结构也解释了这种酶自然发生的错义突变导致 PH2 的有害影响。 (c) 2006 Elsevier Ltd 保留所有权利。
Human glyoxylate reductase/hydroxypyruvate reductase (GRHPR) is a D-plays a critical role in the removal of the metabolic by-product glyoxylate from within the liver. Deficiency of this enzyme is the underlying cause of primary hyperoxaluria. type 2 (PH2) and leads to increased urinary oxalate levels, formation of kidney stones and renal failure. Here we describe the crystal structure of human GRHPR at 2.2 angstrom resolution. There are four copies of GRHPR in the crystallographic asymmetric unit: in each homodimer, one subunit forms a ternary (enzyme + NADPH + reduced substrate) complex, and the other a binary (enzyme + NADPH) form. The spatial arrangement of the two enzyme domains is the same in binary and ternary forms. This first crystal structure of a true ternary complex of an enzyme from this family demonstrates the relationship of substrate and catalytic residues within the active site, confirming earlier proposals of the mode of substrate binding, stereospecificity and likely catalytic mechanism for these enzymes. GRHPR has an unusual substrate specificity, preferring glyoxylate and hydroxypyruvate, but not pyruvate. A tryptophan residue (Trp141) from the neighbouring subunit of the dimer is projected into the active site region and appears to contribute to the selectivity for hydroxypyruvate. This first crystal structure of a human GRHPR enzyme also explains the deleterious effects of naturally occurring missense mutations of this enzyme that lead to PH2. (c) 2006 Elsevier Ltd All rights reserved.