Structure and mechanism of a bacterial β-glucosaminidase having O-GlcNAcase activity
Structure and mechanism of a bacterial β-glucosaminidase having O-GlcNAcase activity
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DOI：
10.1038/nsmb1079
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发表时间：
2006-04-01
影响因子：
16.8
通讯作者：
Davies, GJ
中科院分区：
文献类型：
--
作者：
Dennis, RJ;Taylor, EJ;Davies, GJ
O-GlcNAc是核质蛋白的丝氨酸和苏氨酸残基的丰富的翻译后修饰。这种修饰仅在高等真核生物中发现，是一种动态修饰，通常与磷酸化相互作用。以类似于磷酸酶的方式，称为O-GlcNAc酶的糖苷水解酶从修饰的蛋白质中切割O-GlcNAc。与人类O-GlcNAcase序列高度相似的酶也存在于人类病原体和共生体中。我们报告的三维结构的O-GlcNAcase从人类肠道共生体多形拟杆菌无论是在其天然形式和复杂的模拟反应中间体。突变和动力学研究表明，细菌酶，非常类似于其人类对应物，通过一个不寻常的“底物辅助”催化机制，这将通知酶抑制剂的合理设计。
O-GlcNAc is an abundant post-translational modification of serine and threonine residues of nucleocytoplasmic proteins. This modification, found only within higher eukaryotes, is a dynamic modification that is often reciprocal to phosphorylation. In a manner analogous to phosphatases, a glycoside hydrolase termed O-GlcNAcase cleaves O-GlcNAc from modified proteins. Enzymes with high sequence similarity to human O-GlcNAcase are also found in human pathogens and symbionts. We report the three-dimensional structure of O-GlcNAcase from the human gut symbiont Bacteroides thetaiotaomicron both in its native form and in complex with a mimic of the reaction intermediate. Mutagenesis and kinetics studies show that the bacterial enzyme, very similarly to its human counterpart, operates via an unusual 'substrate-assisted' catalytic mechanism, which will inform the rational design of enzyme inhibitors.