Crystal structure of the catalytic unit of thermostable GH87 α-1,3-glucanase from Streptomyces thermodiastaticus strain HF3-3
Crystal structure of the catalytic unit of thermostable GH87 α-1,3-glucanase from Streptomyces thermodiastaticus strain HF3-3
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DOI：
10.1016/j.bbrc.2020.09.133
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发表时间：
2020-12-17
影响因子：
3.1
通讯作者：
Hibi, Takao
中科院分区：
文献类型：
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作者：
Itoh, Takafumi;Panti, Niphawan;Hibi, Takao
α-1，3-葡聚糖是一种由D-葡萄糖(GLC)组成的均聚物，是一种存在于牙菌斑中的胞外多糖，属于链球菌属。嗜热链霉菌HF3-3的α-1，3-葡聚糖酶(AGL-ST)是一种耐热的α-1，3-葡聚糖酶，属于糖苷水解酶家族87(GH87)，专一性地内切降解α-1，3-葡聚糖。这种酶有可能抑制牙菌斑的产生，并用于生物技术应用。在这里，我们展示了用X射线结晶学在1.16埃分辨率下测定的AgL-St催化单元的结构。催化单元由两个模块组成，一个是β-三明治折叠模块，另一个是右旋β-螺旋折叠模块，它类似于其他来自环状芽孢杆菌的具有结构特征的GH87酶。KA-304和甘露糖拟杆菌。FH11，彼此之间具有中等的序列同源性(催化单元之间约27%)。但AgL-St的尺寸较小，热稳定性较好。锚定β-螺旋折叠的C-末端线圈的二硫键只存在于AGL-ST的催化单元中，这有望有助于热稳定性。(C)2020 Elsevier Inc.保留所有权利。
alpha-1,3-Glucan is a homopolymer composed of D-glucose (Glc) and it is an extracellular polysaccharide found in dental plaque due to Streptococcus species. alpha-1,3-Glucanase from Streptomyces thermodiastaticus strain HF3-3 (Agl-ST) has been identified as a thermostable alpha-1,3-glucanase, which is classified into glycoside hydrolase family 87 (GH87) and specifically hydrolyzes alpha-1,3-glucan with an endo-action. The enzyme has a potential to inhibit the production of dental plaque and to be used for biotechnological applications. Here we show the structure of the catalytic unit of Agl-ST determined at 1.16 angstrom resolution using X-ray crystallography. The catalytic unit is composed of two modules, a beta-sandwich fold module, and a right-handed beta-helix fold module, which resembles other structural characterized GH87 enzymes from Bacillus circulans str. KA-304 and Paenibacillus glycanilyticus str. FH11, with moderate sequence identities between each other (approximately 27% between the catalytic units). However, Agl-ST is smaller in size and more thermally stable than the others. A disulfide bond that anchors the C-terminal coil of the beta-helix fold, which is expected to contribute to thermal stability only exists in the catalytic unit of Agl-ST. (C) 2020 Elsevier Inc. All rights reserved.