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Crystal structure of GH30-7 endoxylanase C from the filamentous fungus Talaromyces cellulolyticus.
Acta Crystallographica Section F ( IF 1.1 ) Pub Date : 2020-08-03 , DOI: 10.1107/s2053230x20009024
Yusuke Nakamichi 1 , Tatsuya Fujii 1 , Masahiro Watanabe 1 , Akinori Matsushika 1 , Hiroyuki Inoue 1
Affiliation  

GH30‐7 endoxylanase C from the cellulolytic fungus Talaromyces cellulolyticus (TcXyn30C) belongs to glycoside hydrolase family 30 subfamily 7, and specifically releases 22‐(4‐O‐methyl‐α‐d‐glucuronosyl)‐xylobiose from glucuronoxylan, as well as various arabino‐xylooligosaccharides from arabinoxylan. TcXyn30C has a modular structure consisting of a catalytic domain and a C‐terminal cellulose‐binding module 1 (CBM1). In this study, the crystal structure of a TcXyn30C mutant which lacks the CBM1 domain was determined at 1.65 Å resolution. The structure of the active site of TcXyn30C was compared with that of the bifunctional GH30‐7 xylanase B from T. cellulolyticus (TcXyn30B), which exhibits glucuronoxylanase and xylobiohydrolase activities. The results revealed that TcXyn30C has a conserved structural feature for recognizing the 4‐O‐methyl‐α‐d‐glucuronic acid (MeGlcA) substituent in subsite −2b. Additionally, the results demonstrated that Phe47 contributes significantly to catalysis by TcXyn30C. Phe47 is located in subsite −2b and also near the C‐3 hydroxyl group of a xylose residue in subsite −2a. Substitution of Phe47 with an arginine residue caused a remarkable decrease in the catalytic efficiency towards arabinoxylan, suggesting the importance of Phe47 in arabinoxylan hydrolysis. These findings indicate that subsite −2b of TcXyn30C has unique structural features that interact with arabinofuranose and MeGlcA substituents.

中文翻译:

来自丝状真菌解纤维素踝节菌的 GH30-7 木聚糖内切酶 C 的晶体结构。

来自纤维素分解真菌Talaromyces cellulolyticus ( Tc Xyn30C) 的 GH30-7 木聚糖内切酶 C 属于糖苷水解酶家族 30 亚家族 7,并且还从葡糖醛酸木聚糖中特异性释放 2 2 -(4- O-甲基-α- d-葡萄糖醛酸基)-木二糖作为来自阿拉伯木聚糖的各种阿拉伯低聚木糖。Tc Xyn30C 具有由催化结构域和 C 端纤维素结合模块 1 (CBM1) 组成的模块化结构。在本研究中,以 1.65 Å 分辨率测定了缺乏 CBM1 结构域的Tc Xyn30C 突变体的晶体结构。将Tc Xyn30C的活性位点结构与来自T. cellulolyticus的双功能 GH30-7 木聚糖酶 B ( Tc Xyn30B)的活性位点结构进行比较,后者表现出葡糖醛酸木聚糖酶和木糖二糖水解酶活性。结果表明,Tc Xyn30C具有保守的结构特征,可识别-2b位点中的4- O-甲基-α- d-葡萄糖醛酸(MeGlcA)取代基。此外,结果表明 Phe47 对Tc Xyn30C 的催化作用有显着贡献。Phe47 位于子位点 -2b 中,并且也靠近子位点 -2a 中木糖残基的 C-3 羟基。用精氨酸残基取代 Phe47 导致阿拉伯木聚糖的催化效率显着下降,表明 Phe47 在阿拉伯木聚糖水解中的重要性。这些发现表明Tc Xyn30C 的 -2b 亚位点具有与阿拉伯呋喃糖和 MeGlcA 取代基相互作用的独特结构特征。
更新日期:2020-08-03
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