Fucosylation of the innermost GlcNAc of N-glycans by fucosyltransferase 8 (FUT8) is an important step in the maturation of complex and hybrid N-glycans. This simple modification can dramatically affect the activities and half-lives of glycoproteins, effects that are relevant to understanding the invasiveness of some cancers, development of mAb therapeutics, and the etiology of a congenital glycosylation disorder. The acceptor substrate preferences of FUT8 are well-characterized and provide a framework for understanding N-glycan maturation in the Golgi; however, the structural basis of these substrate preferences and the mechanism through which catalysis is achieved remain unknown. Here we describe several structures of mouse and human FUT8 in the apo state and in complex with GDP, a mimic of the donor substrate, and with a glycopeptide acceptor substrate at 1.80-2.50 Å resolution. These structures provide insights into a unique conformational change associated with donor substrate binding, common strategies employed by fucosyltransferases to coordinate GDP, features that define acceptor substrate preferences, and a likely mechanism for enzyme catalysis. Together with molecular dynamics simulations, the structures also revealed how FUT8 dimerization plays an important role in defining the acceptor substrate-binding site. Collectively, this information significantly builds on our understanding of the core fucosylation process.

中文翻译：

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岩藻糖基转移酶对底物识别和催化的结构基础8。

岩藻糖基转移酶8（FUT8）对N-聚糖最内层GlcNAc的岩藻糖基化作用是复杂和杂合N-聚糖成熟的重要步骤。这种简单的修饰会极大地影响糖蛋白的活性和半衰期，与理解某些癌症的侵袭性，mAb治疗剂的开发以及先天性糖基化疾病的病因有关的作用。FUT8的受体底物偏爱具有良好的特征，并为理解高尔基体中的N-聚糖成熟提供了框架。然而，这些底物偏好的结构基础和实现催化的机理仍然未知。在这里，我们描述了载脂蛋白状态的小鼠和人类FUT8的几种结构，并与GDP（一种供体底物的模拟物）形成了复杂的关系，并具有1.80-2.50Å分辨率的糖肽受体底物。这些结构提供了与供体底物结合相关的独特构象变化，岩藻糖基转移酶用来协调GDP的通用策略，定义受体底物偏好的特征以及酶催化的可能机制的见解。与分子动力学模拟一起，该结构还揭示了FUT8二聚化如何在定义受体底物结合位点中发挥重要作用。总的来说，这些信息很大程度上建立在我们对核心岩藻糖基化过程的理解上。定义受体底物偏好的功能，以及酶催化的可能机制。与分子动力学模拟一起，该结构还揭示了FUT8二聚化如何在定义受体底物结合位点中发挥重要作用。总的来说，这些信息很大程度上建立在我们对核心岩藻糖基化过程的理解上。定义受体底物偏好的功能，以及酶催化的可能机制。与分子动力学模拟一起，该结构还揭示了FUT8二聚化如何在定义受体底物结合位点中发挥重要作用。总的来说，这些信息很大程度上建立在我们对核心岩藻糖基化过程的理解上。