A novel extracellular multicopper oxidase from Phanerochaete chrysosporium with ferroxidase activity
A novel extracellular multicopper oxidase from Phanerochaete chrysosporium with ferroxidase activity
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DOI：
10.1128/aem.69.10.6257-6263.2003
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发表时间：
2003-10-01
影响因子：
4.4
通讯作者：
Cullen, D
中科院分区：
文献类型：
--
作者：
Larrondo, LF;Salas, L;Cullen, D
白色腐烂担子菌黄孢原毛平革菌对木质素的降解涉及多种细胞外氧化酶，包括木质素过氧化物酶、锰过氧化物酶和一种产生过氧化物的酶--乙二醛氧化酶。最近的研究表明，这种真菌也可能产生漆酶，但这些结论一直存在争议。我们确定了四个相关的漆酶和铁氧化酶（Fet 3）的公开可用的P. chrysosporium数据库中的搜索序列。一个基因，指定餐，有一个典型的真核分泌信号，并在确定的媒体和殖民木材转录。结构分析和多重比对鉴定了漆酶和Fet 3序列共有的残基。在构巢曲霉中表达的重组MCO 1（rMCO 1）蛋白的分子量为78 kDa，通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测定，并通过紫外可见光谱确认铜I型中心。rMCO 1氧化各种化合物，包括2，2 '-连氮基（双-3-乙基苯并噻唑啉-6-磺酸盐）（ABTS）和芳香胺，尽管酚类化合物是较差的底物。最佳底物是Fe 2+，K-m接近2 μ M。总的来说，这些结果表明，P. chrysosporium基因组不编码一个典型的漆酶，而是编码一个独特的细胞外多铜氧化酶具有强的铁氧化酶活性。
Lignin degradation by the white rot basidiomycete Phanerochaete chrysosporium involves various extracellular oxidative enzymes, including lignin peroxidase, manganese peroxidase, and a peroxide-generating enzyme, glyoxal oxidase. Recent studies have suggested that laccases also may be produced by this fungus, but these conclusions have been controversial. We identified four sequences related to laccases and ferroxidases (Fet3) in a search of the publicly available P. chrysosporium database. One gene, designated meal, has a typical eukaryotic secretion signal and is transcribed in defined media and in colonized wood. Structural analysis and multiple alignments identified residues common to laccase and Fet3 sequences. A recombinant MCO1 (rMCO1) protein expressed in Aspergillus nidulans had a molecular mass of 78 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the copper I-type center was confirmed by the UV-visible spectrum. rMCO1 oxidized various compounds, including 2,2'-azino(bis-3-ethylbenzthiazoline-6-sulfonate) (ABTS) and aromatic amines, although phenolic compounds were poor substrates. The best substrate was Fe2+, with a K-m close to 2 muM. Collectively, these results suggest that the P. chrysosporium genome does not encode a typical laccase but rather encodes a unique extracellular multicopper oxidase with strong ferroxidase activity.