Qin Xing, Luo Huiying, Zhang Xiaoyu, Yao Bin, Ma Fuying, Su Xiaoyun
1Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China.
2Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Beijing, 100081 China.
Biotechnol Biofuels. 2018 Nov 8;11:302. doi: 10.1186/s13068-018-1303-9. eCollection 2018.
The white rot fungus exhibits a great potential in biopretreatment of lignocellulose as well as in biodegradation of xenobiotic compounds by extracellular ligninolytic enzymes. Among these enzymes, the possible involvement of dye-decolorizing peroxidase (DyP) in lignin degradation is not clear yet.
Based on the extracellular enzyme activities and secretome analysis, CD2 produced DyPs as the main ligninolytic enzymes when grown in Kirk's medium supplemented with lignin. Further transcriptome analysis revealed that induced transcription of genes encoding DyPs was accompanied by the increased expression of transcripts for HO-generating enzymes such as alcohol oxidase, pyranose 2-oxidase, and glyoxal oxidases. Meanwhile, accumulation of transcripts for glycoside hydrolase and protease was observed, in agreement with abundant proteins. Moreover, the biochemical analysis of DyP2 and DyP1 confirmed that DyPs were able to catalyze the oxidation of typical peroxidases substrates ABTS, phenolic lignin compounds DMP, and guaiacol as well as non-phenolic lignin compound, veratryl alcohol. More importantly, DyP1 enhanced catalytic activity for veratryl alcohol oxidation in the presence of mediator 1-hydroxybenzotriazole, which was similar to the laccase/1-hydroxybenzotriazole system.
The results proved for the first time that DyPs depolymerized lignin individually, combining catalytic features of different peroxidases on the functional level. Therefore, DyPs may be considered an important part of ligninolytic system in wood-decaying fungi.
白腐真菌在木质纤维素的生物预处理以及通过细胞外木质素分解酶对异源生物化合物的生物降解方面具有巨大潜力。在这些酶中，染料脱色过氧化物酶（DyP）在木质素降解中的可能作用尚不清楚。
基于细胞外酶活性和分泌组分析，CD2在添加木质素的柯克培养基中生长时产生DyP作为主要的木质素分解酶。进一步的转录组分析表明，编码DyP的基因的诱导转录伴随着产HO酶如醇氧化酶、吡喃糖2-氧化酶和乙二醛氧化酶转录本表达的增加。同时，观察到糖苷水解酶和蛋白酶转录本的积累，这与丰富的蛋白质一致。此外，DyP2和DyP1的生化分析证实，DyP能够催化典型过氧化物酶底物ABTS、酚类木质素化合物DMP和愈创木酚以及非酚类木质素化合物藜芦醇的氧化。更重要的是，DyP1在介质1-羟基苯并三唑存在下增强了对藜芦醇氧化的催化活性，这与漆酶/1-羟基苯并三唑体系相似。
结果首次证明DyP单独使木质素解聚，在功能水平上结合了不同过氧化物酶的催化特征。因此，DyP可被认为是木材腐朽真菌中木质素分解系统的重要组成部分。
