Structural insights into polysaccharide recognition by Flavobacterium johnsoniae dextranase, a member of glycoside hydrolase family 31
Structural insights into polysaccharide recognition by Flavobacterium johnsoniae dextranase, a member of glycoside hydrolase family 31
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约氏黄杆菌葡聚糖酶（糖苷水解酶家族 31 的成员）识别多糖的结构见解
DOI：
10.1111/febs.15074
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Atsushi Nishikawa and Takashi Tonozuka
中科院分区：
文献类型：
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作者：
Kenta Tsutsumi;Yoshifumi Gozu;Atsushi Nishikawa and Takashi Tonozuka
糖苷水解酶家族（GH） 31包含多种酶，但主要成员是作用于相对较小的寡糖的酶，如α‐葡萄糖苷酶。在这里，我们测定了来自f。能水解多糖葡聚糖的强生菌。FjDex31A由四个结构域组成：一个N端结构域、一个催化结构域、一个近端C端结构域和一个远端C端结构域，这在典型的GH31酶中观察到。然而，FjDex31A活性位点残基的结构，除了子位−1外，与其他GH31酶明显不同。FjDex31A与异糖三糖复合物的结构表明，Gly273和Tyr524，以及Trp376和Leu308 - cisGln309，都是FjDex31A所特有的，两者都与α -葡萄糖亚位- 2残基相互作用。位点定向诱变Gly273和Tyr524导致多糖葡聚糖和普鲁兰的水解减少，以及双糖异麦芽糖的水解减少。这些结果表明，无论底物的糖链长度如何，FjDex31A在亚位- 2上与底物的结合可能对其活性很重要。数据库结构数据可在蛋白质数据库中获得，登录号为6JR6, 6JR7和6JR8。
Glycoside hydrolase family (GH) 31 contains a large variety of enzymes, but the major members are enzymes that act on relatively small oligosaccharides such as α‐glucosidase. Here, we determined the crystal structure ofFlavobacterium johnsoniaedextranase (FjDex31A), an enzyme fromF. johnsoniaethat hydrolyzes a polysaccharide, dextran. FjDex31A is composed of four domains: an N‐terminal domain, a catalytic domain, a proximal C‐terminal domain, and a distal C‐terminal domain, as observed in typical GH31 enzymes. However, the architecture of active site residues in FjDex31A, other than subsite −1, is markedly different from that of other GH31 enzymes. The FjDex31A structure in complex with isomaltotriose shows that Gly273 and Tyr524, both of which interact with an α‐glucose residue at subsite −2, as well as Trp376 and Leu308‐cisGln309, are especially unique to FjDex31A. Site‐directed mutagenesis of Gly273 and Tyr524 resulted in a decrease in the hydrolysis of polysaccharides dextran and pullulan, as well as that of the disaccharide isomaltose. These results suggest that, regardless of the length of sugar chains of the substrates, binding of FjDex31A to the substrates at subsite −2 is likely to be important for its activity.DatabaseStructural data are available in the Protein Data Bank under the accession numbers 6JR6, 6JR7, and 6JR8.