Analyzing the Substrate Specificity of a Class of Long‐Horned‐Beetle‐Derived Xylanases by Using Synthetic Arabinoxylan Oligo‐ and Polysaccharides
Analyzing the Substrate Specificity of a Class of Long‐Horned‐Beetle‐Derived Xylanases by Using Synthetic Arabinoxylan Oligo‐ and Polysaccharides
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DOI：
10.1002/cbic.201900687
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发表时间：
2019-12
期刊：
影响因子：
3.2
通讯作者：
Y. Pauchet;Colin Ruprecht;F. Pfrengle
中科院分区：
文献类型：
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作者：
Y. Pauchet;Colin Ruprecht;F. Pfrengle
食木的长角甲虫在充满挑战的环境中茁壮成长。为了获得营养，它们在肠液中分泌植物细胞壁降解酶;其中包括糖苷水解酶家族5（GH5_2）的亚家族2的纤维素酶。最近，我们发现几种甲虫来源的GH5_2使用木聚糖作为底物而不是纤维素，这对于这个酶家族来说是不寻常的。在这里，我们使用商业上可获得的底物和合成的阿拉伯木聚糖寡聚物和多糖来分析来自日本粒肩星天牛的GH5_2木聚糖酶（AJAGH5_2 - 1）的底物特异性。我们证明AJAGH5_2 - 1以不同于经典木聚糖酶家族如GH 10和GH 11的方式加工阿拉伯木聚糖多糖。AJAGH5_2 - 1对长寡糖有活性，并且仅在以下情况下在取代的木糖残基的非还原末端（位置+1）切割：1）切割位点的上游和下游存在三个木糖残基，以及2）位置-1、-2、+2和+3的木糖残基未被取代。
Xylophagous long‐horned beetles thrive in challenging environments. To access nutrients, they secrete plant‐cell‐wall‐degrading enzymes in their gut fluid; among them are cellulases of the subfamily 2 of glycoside hydrolase family 5 (GH5_2). Recently, we discovered that several beetle‐derived GH5_2s use xylan as a substrate instead of cellulose, which is unusual for this family of enzymes. Here, we analyze the substrate specificity of a GH5_2 xylanase from the beetle Apriona japonica (AJAGH5_2‐1) using commercially available substrates and synthetic arabinoxylan oligo‐ and polysaccharides. We demonstrate that AJAGH5_2‐1 processes arabinoxylan polysaccharides in a manner distinct from classical xylanase families such as GH10 and GH11. AJAGH5_2‐1 is active on long oligosaccharides and cleaves at the non‐reducing end of a substituted xylose residue (position +1) only if: 1) three xylose residues are present upstream and downstream of the cleavage site, and 2) xylose residues at positions −1, −2, +2 and +3 are not substituted.