Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, E-28040 Madrid, Spain.
Biotechnol Biofuels. 2014 Jan 3;7(1):2. doi: 10.1186/1754-6834-7-2.
The genome of Pleurotus ostreatus, an important edible mushroom and a model ligninolytic organism of interest in lignocellulose biorefineries due to its ability to delignify agricultural wastes, was sequenced with the purpose of identifying and characterizing the enzymes responsible for lignin degradation.
Heterologous expression of the class II peroxidase genes, followed by kinetic studies, enabled their functional classification. The resulting inventory revealed the absence of lignin peroxidases (LiPs) and the presence of three versatile peroxidases (VPs) and six manganese peroxidases (MnPs), the crystal structures of two of them (VP1 and MnP4) were solved at 1.0 to 1.1 Å showing significant structural differences. Gene expansion supports the importance of both peroxidase types in the white-rot lifestyle of this fungus. Using a lignin model dimer and synthetic lignin, we showed that VP is able to degrade lignin. Moreover, the dual Mn-mediated and Mn-independent activity of P. ostreatus MnPs justifies their inclusion in a new peroxidase subfamily. The availability of the whole POD repertoire enabled investigation, at a biochemical level, of the existence of duplicated genes. Differences between isoenzymes are not limited to their kinetic constants. Surprising differences in their activity T50 and residual activity at both acidic and alkaline pH were observed. Directed mutagenesis and spectroscopic/structural information were combined to explain the catalytic and stability properties of the most interesting isoenzymes, and their evolutionary history was analyzed in the context of over 200 basidiomycete peroxidase sequences.
The analysis of the P. ostreatus genome shows a lignin-degrading system where the role generally played by LiP has been assumed by VP. Moreover, it enabled the first characterization of the complete set of peroxidase isoenzymes in a basidiomycete, revealing strong differences in stability properties and providing enzymes of biotechnological interest.
由于其能够分解农业废弃物中的木质素，因此被认为是木质纤维素生物炼制厂中感兴趣的木质素降解模型生物，双孢蘑菇（Pleurotus ostreatus）的基因组已被测序，目的是鉴定和描述负责木质素降解的酶。
通过异源表达 II 类过氧化物酶基因，并进行动力学研究，对其进行了功能分类。由此产生的清单显示缺乏木质素过氧化物酶（LiPs），但存在三种多功能过氧化物酶（VPs）和六种锰过氧化物酶（MnPs），其中两种酶（VP1 和 MnP4）的晶体结构已解决在 1.0 到 1.1 Å，显示出显著的结构差异。基因扩展支持这两种过氧化物酶类型在真菌白腐生活方式中的重要性。使用木质素模型二聚体和合成木质素，我们表明 VP 能够降解木质素。此外，P. ostreatus MnPs 的双 Mn 介导和 Mn 非依赖性活性证明它们属于新的过氧化物酶亚家族。整个 POD repertoire 的可用性使我们能够在生化水平上研究存在的重复基因。同工酶之间的差异不仅限于其动力学常数。在酸性和碱性 pH 值下，观察到 T50 和残余活性的惊人差异。定点突变和光谱/结构信息相结合，解释了最有趣同工酶的催化和稳定性特性，并在 200 多种担子菌过氧化物酶序列的背景下分析了它们的进化历史。
P. ostreatus 基因组的分析显示出一种木质素降解系统，其中 LiP 通常所扮演的角色由 VP 承担。此外，它首次对担子菌中完整的过氧化物酶同工酶进行了特征描述，揭示了稳定性特性的强烈差异，并提供了具有生物技术兴趣的酶。
