Identification and characterization of two xyloglucan-specific endo-1,4-glucanases in Aspergillus oryzae
Identification and characterization of two xyloglucan-specific endo-1,4-glucanases in Aspergillus oryzae
复制标题
米曲霉中两种木葡聚糖特异性内切 1,4-葡聚糖酶的鉴定和表征
DOI：
10.1007/s00253-020-10883-7
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发表时间：
2020
影响因子：
5
通讯作者：
Yaoi Katsuro
中科院分区：
文献类型：
--
作者：
Matsuzawa Tomohiko;Kameyama Akihiko;Nakamichi Yusuke;Yaoi Katsuro
摘要米曲霉产生糖苷水解酶来降解木葡聚糖。我们鉴定并表征了两种木葡聚糖特异性内切 1,4-葡聚糖酶（木葡聚糖酶），命名为 Xeg12A 和 Xeg5A。根据其氨基酸序列，Xeg12A和Xeg5A分别分为糖苷水解酶家族GH12和GH5。 Xeg12A 将罗望子种子木葡聚糖多糖降解为含有四个吡喃葡萄糖基残基作为主链的木葡聚糖寡糖，包括七糖 (XXXG: Glc4Xyl3)、八糖 (XXLG 和 XLXG: Glc4Xyl3Gal1) 和九糖 (XLLG: Glc4Xyl3Gal2)。相比之下，Xeg5A 从木葡聚糖产生各种木葡聚糖寡糖。 Xeg5A 不仅能将木葡聚糖水解成 XXXG、XXLG/XLXG 和 XLLG，还能水解成二糖（异春糖：Glc1Xyl1）、四糖（XX：Glc2Xyl2 和 LG：Glc2Xyl1Gal1）等。 Xeg12A 是一种典型的内解离型木葡聚糖酶，可重复水解和解吸木葡聚糖。相反，Xeg5A 充当内加工型木葡聚糖酶，其逐步水解木葡聚糖而不解吸。这些结果表明，虽然Xeg12A和Xeg5A都有助于木葡聚糖的降解，但它们对木葡聚糖具有不同的活性模式，并且Xeg5A的水解机制与其他已知的GH5酶相比是独特的。要点•我们在米曲霉中鉴定了两种木葡聚糖酶，Xeg12A和Xeg5A。•Xeg12A和Xeg5A的活性模式和区域特异性明显不同。•Xeg5A 是一种独特的木葡聚糖酶，可产生低分子量寡糖。
AbstractAspergillus oryzaeproduces glycoside hydrolases to degrade xyloglucan. We identified and characterized two xyloglucan-specific endo-1,4-glucanases (xyloglucanases) named Xeg12A and Xeg5A. Based on their amino acid sequences, Xeg12A and Xeg5A were classified into glycoside hydrolase families GH12 and GH5, respectively. Xeg12A degrades tamarind seed xyloglucan polysaccharide into xyloglucan oligosaccharides containing four glucopyranosyl residues as main chains, including heptasaccharides (XXXG: Glc4Xyl3), octasaccharides (XXLG and XLXG: Glc4Xyl3Gal1), and nonasaccharides (XLLG: Glc4Xyl3Gal2). By contrast, Xeg5A produces various xyloglucan oligosaccharides from xyloglucan. Xeg5A hydrolyzes xyloglucan into not only XXXG, XXLG/XLXG, and XLLG but also disaccharides (isoprimeverose: Glc1Xyl1), tetrasaccharides (XX: Glc2Xyl2and LG: Glc2Xyl1Gal1), and so on. Xeg12A is a typical endo-dissociative-type xyloglucanase that repeats hydrolysis and desorption from xyloglucan. Conversely, Xeg5A acts as an endo-processive-type xyloglucanase that hydrolyzes xyloglucan progressively without desorption. These results indicate that although both Xeg12A and Xeg5A contribute to the degradation of xyloglucan, they have different modes of activity toward xyloglucan, and the hydrolysis machinery of Xeg5A is unique compared with that of other known GH5 enzymes.Key points•We identified two xyloglucanases, Xeg12A and Xeg5A, in A. oryzae.•Modes of activity and regiospecificities of Xeg12A and Xeg5A were clearly different.•Xeg5A is a unique xyloglucanase that produces low-molecular-weight oligosaccharides.