Department of Food and Environmental Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland.
Appl Microbiol Biotechnol. 2011 May;90(4):1323-32. doi: 10.1007/s00253-011-3157-y. Epub 2011 Mar 26.
Schizophyllum commune produces an α-glucuronidase that is active on polymeric xylan, while the ascomycete α-glucuronidases are only active on xylan oligomers. In this study, we have identified the gene (agu1) encoding this enzyme and confirmed the functionality by overexpression of the gene in S. commune and degradation of aldopentauronic acids, (MeGlcA)(3)-Xyl(4), in the cultivation medium of the transformants. Expression analysis demonstrated that agu1 is not co-regulated with the predominant xylanase-encoding gene (xynA) of S. commune. The detailed sequence analysis of Agu1 demonstrated that this gene belongs to a novel glycoside hydrolase family (GH115) that also contains candidate genes from ascomycete fungi and bacteria. Phylogenetic analysis showed that the fungal GH115 α-glucuronidases are distinctly separate from the prokaryotic clade and distributed over three branches. The identification of putative genes encoding this enzyme in industrial fungi, such as Aspergillus oryzae and Hypocrea jecorina, will provide a starting point for further analysis of the importance of this enzyme for the hydrolysis of plant biomass.
糙皮侧耳产生一种α-葡糖苷酸酶，该酶能作用于聚合木聚糖，而子囊菌的α-葡糖苷酸酶仅能作用于木聚糖低聚物。在本研究中，我们鉴定了编码该酶的基因（agu1），并通过在糙皮侧耳中过表达该基因以及在转化体的培养物中降解醛戊糖酸（MeGlcA）（3）-Xyl（4），证实了其功能。表达分析表明，agu1 与糙皮侧耳的主要木聚糖酶编码基因（xynA）没有共同调控。对 Agu1 的详细序列分析表明，该基因属于一个新的糖苷水解酶家族（GH115），其中还包含来自子囊菌真菌和细菌的候选基因。系统发育分析表明，真菌 GH115 α-葡糖苷酸酶与原核分支明显分离，并分布在三个分支上。在工业真菌，如米曲霉和栓菌中鉴定出编码该酶的假定基因，将为进一步分析该酶对植物生物质水解的重要性提供起点。
