Comparative anatomy of the aldo-keto reductase superfamily
Comparative anatomy of the aldo-keto reductase superfamily
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DOI：
10.1042/bj3260625
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发表时间：
1997-09-15
影响因子：
4.1
通讯作者：
Penning, TM
中科院分区：
文献类型：
--
作者：
Jez, JM;Bennett, MJ;Penning, TM
醛酮还原酶是一个具有广泛代谢底物的蛋白质超家族，包括醛糖还原酶、醛还原酶、羟基类固醇脱氢酶和二氢二醇脱氢酶。通过结合多序列比对与已知的三维结构和定点诱变研究的结果，我们已经开发了一个结构/功能分析这个超家族。我们的研究表明，（α/β）（8）-桶折叠为NAD（P）（H）-依赖性催化活性提供了一个共同的支架，底物特异性由桶C-末端侧的环的变化决定。所有的醛酮还原酶都依赖于烟酰胺辅因子进行催化，并保留相似的辅因子结合位点，即使在氨基酸序列同一性小于30%的蛋白质中也是如此。同样，醛酮还原酶活性位点是高度保守的。然而，我们的比对表明，活性位点中单个残基的变化可能将反应机制从羰基氧化还原改变为碳-碳双键还原，如在超家族的3-氧代-5 β-类固醇4-脱氢酶（Delta（4）-3-ketosteroid 5 β-reductases）中。建议的基板结合口袋的比较表明残基54和118，附近的活性位点，糖和类固醇底物之间的可能的歧视。此外，小鼠肝脏17 β-羟基类固醇脱氢酶和大鼠卵巢20 α-羟基类固醇脱氢酶的序列比对和随后的同源性建模表明，桶的C-末端侧的三个环在确定羟基类固醇脱氢酶的位置和立体特异性中发挥潜在的作用。最后，我们提出，醛酮还原酶超家族可能代表了一个例子，从祖先的多功能氧化还原酶和收敛进化到相同的活性位点星座的短链脱氢酶/还原酶超家族的一个例子发散进化。
The aldo-keto reductases metabolize a wide range of substrates and are potential drug targets, This protein superfamily includes aldose reductases, aldehyde reductases, hydroxysteroid dehydro-genases and dihydrodiol dehydrogenases. By combining multiple sequence alignments with known three-dimensional structures and the results of site-directed mutagenesis studies, we have developed a structure/function analysis of this superfamily. Our studies suggest that the (alpha/beta)(8)-barrel fold provides a common scaffold for an NAD(P)(H)-dependent catalytic activity, with substrate specificity determined by variation of loops on the C-terminal side of the barrel. All the aldo-keto reductases are dependent on nicotinamide cofactors for catalysis and retain a similar cofactor binding site, even among proteins with less than 30% amino acid sequence identity. Likewise, the aldo-keto reductase active site is highly conserved. However, our alignments indicate that variation of a single residue in the active site may alter the reaction mechanism from carbonyl oxidoreduction to carbon-carbon double-bond reduction, as in the 3-oxo-5 beta-steroid 4-dehydrogenases (Delta(4)-3-ketosteroid 5 beta-reductases) of the superfamily. Comparison of the proposed substrate binding pocket suggests residues 54 and 118, near the active site, as possible discriminators between sugar and steroid substrates. In addition, sequence alignment and subsequent homology modelling of mouse liver 17 beta-hydroxysteroid dehydrogenase and rat ovary 20 alpha-hydroxysteroid dehydrogenase indicate that three loops on the C-terminal side of the barrel play potential roles in determining the positional and stereo-specificity of the hydroxysteroid dehydrogenases. Finally, we propose that the aldo-keto reductase superfamily may represent an example of divergent evolution from an ancestral multifunctional oxidoreductase and an example of convergent evolution to the same active-site constellation as the short-chain dehydrogenase/reductase superfamily.