X-ray crystal structures of rabbit N-acetylglucosaminyltransferase I (GnT I) in complex with donor substrate analogues
X-ray crystal structures of rabbit N-acetylglucosaminyltransferase I (GnT I) in complex with donor substrate analogues
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DOI：
10.1016/j.jmb.2006.04.058
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发表时间：
2006-06-30
影响因子：
5.6
通讯作者：
Rini, James M.
中科院分区：
文献类型：
--
作者：
Gordon, Roni D.;Sivarajah, Prashanth;Rini, James M.
高尔基体驻留糖基转移酶，UDP-N-乙酰-D-葡糖胺：α-3-D-甘露糖苷β-1，2-N-乙酰葡糖胺转移酶I（GnT I），在N-连接聚糖的生物合成中启动高甘露糖寡糖转化为复杂和杂合结构。本文报道了GnT I与UDP-CH 2-GlcNAc（一种不可水解的C-糖苷膦酸酯）、UDP-2-脱氧-2-氟-葡萄糖、UDP-葡萄糖和UDP复合物的X射线晶体结构。总的来说，这些结构为GlcNAc部分及其N-乙酰基在供体底物结合中的重要性提供了证据，以及对柔性318-330环在底物结合和产物释放中所起作用的了解。此外，UDP-CH 2-GlcNAc复合物揭示了一个定义明确的甘油分子准备对供体底物类似物的C1原子进行亲核攻击。该甘油分子的位置和方向使我们能够模拟受体底物的Man α 1，3 Man β 1部分的结合，并基于该模型，提出GnT I受体特异性的主要决定因素的合理化。(c)2006爱思唯尔有限公司保留所有权利。
The Golgi-resident glycosyltransferase, UDP-N-acetyl-D-glucosamine:alpha-3-D-mannoside beta-1,2-N-acetylglucosaminyltransferase I (GnT I), initiates the conversion of high-mannose oligosaccharides to complex and hybrid structures in the biosynthesis of N-linked glycans. Reported here are the X-ray crystal structures of GnT I in complex with UDP-CH2-GIcNAc (a non-hydrolyzable C-glycosidic phosphonate), UDP-2-deoxy-2-fluoro-glucose, UDP-glucose and UDP. Collectively, these structures provide evidence for the importance of the GlcNAc moiety and its N-acetyl group in donor substrate binding, as well as insight into the role played by the flexible 318-330 loop in substrate binding and product release. In addition, the UDP-CH2-GlcNAc complex reveals a well-defined glycerol molecule poised for nucleophilic attack on the C1 atom of the donor substrate analogue. The position and orientation of this glycerol molecule have allowed us to model the binding of the Man alpha 1, 3Man beta 1 moiety of the acceptor substrate and, based on the model, to suggest a rationalization for the main determinants of GnT I acceptor specificity. (c) 2006 Elsevier Ltd. All rights reserved.