Identification and Characterization of a Multifunctional Dye Peroxidase from a Lignin-Reactive Bacterium
Identification and Characterization of a Multifunctional Dye Peroxidase from a Lignin-Reactive Bacterium
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DOI：
10.1021/cb300383y
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发表时间：
2012-12-01
影响因子：
4
通讯作者：
Chang, Michelle C. Y.
中科院分区：
文献类型：
--
作者：
Brown, Margaret E.;Barros, Tiago;Chang, Michelle C. Y.
植物生物质是一种可再生原料，由于难以获得其结构生物聚合物中的碳，尚未得到充分利用。木质素是一种特别具有挑战性的底物，但选择的微生物已经进化出复杂的酶系统，通过自由基介导的氧化过程将其分解。真菌系统的特征在于其脱木质素的能力，但细菌与这种底物反应的能力仍然难以捉摸。因此，我们专注于阐明木质素反应性土壤细菌所使用的策略，并描述其氧化酶系统。我们现在报告的一个不寻常的C-型染料脱色过氧化物酶的Amycolatopsis sp. 75 iv 2（DyP 2），这属于一个家庭的血红素过氧化物酶报道参与细菌木质素降解的鉴定和表征。生化研究表明DyP 2在该家族中具有新的功能，具有多种多样的过氧化物酶和锰过氧化物酶活性（k（cat）/K-M约为10（5）-10（6）M-1 s（-1））。它还具有Mn依赖性氧化酶作用模式，可扩大其底物范围。在2.25埃分辨率的DyP 2的晶体学研究表明存在一个锰结合口袋，并支持其在催化中的关键作用。
Plant biomass represents a renewable feedstock that has not yet been fully tapped because of the difficulty in accessing the carbon in its structural biopolymers. Lignin is an especially challenging substrate, but select microbes have evolved complex systems of enzymes for its breakdown through a radical-mediated oxidation process. Fungal systems are well-characterized for their ability to depolymerize lignin, but the ability of bacteria to react with this substrate remains elusive. We have therefore focused on elucidating strategies used by lignin-reactive soil bacteria and describing their oxidative enzyme systems. We now report the identification and characterization of an unusual C-type dye-decolorizing peroxidase from Amycolatopsis sp. 75iv2 (DyP2), which belongs to a family of heme peroxidases reported to be involved in bacterial lignin degradation. Biochemical studies indicate that DyP2 has novel function for this family, with versatile and high activity both as a peroxidase and Mn peroxidase (k(cat)/K-M approximate to 10(5)-10(6) M-1 s(-1)). It also has a Mn-dependent oxidase mode of action that expands its substrate scope. Crystallographic studies of DyP2 at 2.25 angstrom resolution show the existence of a Mn binding pocket and support its key role in catalysis.