1,3-1,4-α-L-Fucosynthase That Specifically Introduces Lewis a/x Antigens into Type-1/2 Chains
1,3-1,4-α-L-Fucosynthase That Specifically Introduces Lewis a/x Antigens into Type-1/2 Chains
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DOI：
10.1074/jbc.m111.333781
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发表时间：
2012-05-11
影响因子：
4.8
通讯作者：
Katayama, Takane
中科院分区：
文献类型：
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作者：
Sakurama, Haruko;Fushinobu, Shinya;Katayama, Takane
连接在糖缀合物的非还原末端的α-L-岩藻糖基残基构成组织-血型抗原刘易斯（Le）和ABO，并在各种生物过程中发挥基本作用。因此，建立合成抗原的方法对于功能糖组学研究具有重要意义。然而，糖基键，特别是α-L-岩藻糖基键的区域特异性合成很难被化学家和酶学家控制。在这里，我们产生了一种α-L-岩藻糖合酶，其特异性地将Le（a）和Le（x）抗原分别引入1型和2型链;即该酶特异性地接受非还原末端的二糖结构（Gal β 1-3/4GlcNAc），并通过α-（1，4/3）-键将Fuc残基连接到GlcNAc。X射线晶体学研究揭示了这种严格的区域和受体特异性的结构基础，其包括催化重要残基的诱导的适合移动，以及糖苷水解酶家族29中1，3 - 1，4-α-L-岩藻糖苷酶（EC 3.2.1.111）和α-L-岩藻糖苷酶（EC 3.2.1.51）的活性位点结构之间的差异。在这项研究中开发的糖合酶应作为一个潜在的强大的工具，特别是引入Le（a/x）表位不稳定的糖缀合物，包括糖蛋白。挖掘具有严格特异性的糖苷酶可能是糖苷键特异性合成的最有效途径。
alpha-L-Fucosyl residues attached at the non-reducing ends of glycoconjugates constitute histo-blood group antigens Lewis (Le) and ABO and play fundamental roles in various biological processes. Therefore, establishing a method for synthesizing the antigens is important for functional glycomics studies. However, regiospecific synthesis of glycosyl linkages, especially alpha-L-fucosyl linkages, is quite difficult to control both by chemists and enzymologists. Here, we generated an alpha-L-fucosynthase that specifically introduces Le(a) and Le(x) antigens into the type-1 and type-2 chains, respectively; i.e. the enzyme specifically accepts the disaccharide structures (Gal beta 1-3/4GlcNAc) at the non-reducing ends and attaches a Fuc residue via an alpha-(1,4/3)-linkage to the GlcNAc. X-ray crystallographic studies revealed the structural basis of this strict regio- and acceptor specificity, which includes the induced fit movement of the catalytically important residues, and the difference between the active site structures of 1,3-1,4-alpha-L-fucosidase (EC 3.2.1.111) and alpha-L-fucosidase (EC 3.2.1.51) in glycoside hydrolase family 29. The glycosynthase developed in this study should serve as a potentially powerful tool to specifically introduce the Le(a/x) epitopes onto labile glycoconjugates including glycoproteins. Mining glycosidases with strict specificity may represent the most efficient route to the specific synthesis of glycosidic bonds.