Substrate-Guided Front-Face Reaction Revealed by Combined Structural Snapshots and Metadynamics for the Polypeptide N-Acetylgalactosaminyltransferase 2
Substrate-Guided Front-Face Reaction Revealed by Combined Structural Snapshots and Metadynamics for the Polypeptide N-Acetylgalactosaminyltransferase 2
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DOI：
10.1002/anie.201402781
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发表时间：
2014-07-28
影响因子：
16.6
通讯作者：
Hurtado-Guerrero, Ramon
中科院分区：
文献类型：
--
作者：
Lira-Navarrete, Erandi;Iglesias-Fernandez, Javier;Hurtado-Guerrero, Ramon
保留糖基转移酶GalNAc-T2是人类多肽GalNAc-转移酶家族中的一员，负责许多细胞表面蛋白的翻译后修饰。通过使用结构和计算相结合的方法，我们提供了酶在催化循环中的第一组结构快照，并将这些结构快照与量子力学/分子力学(QM/MM)元动力学相结合，在原子-电子水平上揭示了这种保留酶的催化机理。我们的研究为有序的双向动力学机制提供了详细的结构基础，并揭示了底物识别的关键方面，这决定了受体Thr与Ser残基的特异性，并促进了底物N-乙酰糖取代基配位有效糖基转移的正面S(N)I型反应。
The retaining glycosyltransferase GalNAc-T2 is a member of a large family of human polypeptide GalNAc-transferases that is responsible for the post-translational modification of many cell-surface proteins. By the use of combined structural and computational approaches, we provide the first set of structural snapshots of the enzyme during the catalytic cycle and combine these with quantum-mechanics/molecular-mechanics (QM/MM) metadynamics to unravel the catalytic mechanism of this retaining enzyme at the atomic-electronic level of detail. Our study provides a detailed structural rationale for an ordered bi-bi kinetic mechanism and reveals critical aspects of substrate recognition, which dictate the specificity for acceptor Thr versus Ser residues and enforce a front-face S(N)i-type reaction in which the substrate N-acetyl sugar substituent coordinates efficient glycosyl transfer.