Dye-decolorizing peroxidases in Irpex lacteus combining the catalytic properties of heme peroxidases and laccase play important roles in ligninolytic system

Abstract

BackgroundThe white rot fungus Irpex lacteus 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.ResultsBased on the extracellular enzyme activities and secretome analysis, I. lacteus 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 H2O2-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 IlDyP2 and IlDyP1 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, IlDyP1 enhanced catalytic activity for veratryl alcohol oxidation in the presence of mediator 1-hydroxybenzotriazole, which was similar to the laccase/1-hydroxybenzotriazole system.ConclusionsThe 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.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1303-9) contains supplementary material, which is available to authorized users.

DyP-Type Peroxidases: Recent Advances and Perspectives

“…Because wheat straw contains lignocellulose, IlDyP might function in lignin degradation. Consistent with this, IlDyP-1 and IlDyP-2 were reported to degrade the lignin model compound, DMP [ 87 ], although this study reported no data on degradation of lignin itself by IlDyP.…”

Versatile Oxidase and Dehydrogenase Activities of Bacterial Pyranose 2-Oxidase Facilitate Redox Cycling with Manganese Peroxidase In Vitro

“…With this, the (re)polymerization of aromatic lignin constituent radicals (7–10) can be shifted toward depolymerization, as was confirmed for POx and laccase (12). The interaction of POx with manganese, and with (bacterial) DyP in particular (17, 41–43), may be even more complex. Here, the oxidase activity of POx can supply H 2 O 2 to fuel peroxidase-mediated lignin decomposition, whereas the dehydrogenase activity recycles aromatic lignin compounds (radicals), decreases repolymerization, and scavenges highly reactive Mn(III) ions that are produced by the peroxidase (Fig.…”

“…These monosaccharide electron donors could be oxidized by POxs with concomitant H 2 O 2 production, while other potential electron acceptors, like lignin-derived radicals (with their higher affinity for POxs), are expected to be largely absent at this stage. Transcriptome analysis in the white-rot fungus Irpex lacteus grown on lignin indicates a role for POx in the early stages of lignin degradation as well (43). In later stages, POx may preferentially reduce the increasingly present lignin-derived radicals (thereby preventing repolymerization) and reactive Mn(III)-complexes close to the cell, where such intermediates could cause damage to cellular constituents.…”

Cultivation of Mushrooms and Their Lignocellulolytic Enzyme Production Through the Utilization of Agro-Industrial Waste

“…The reaction of compound I with 1 eq electrons from a reducing substrate generates the [FeIV = O] + intermediate compound II [271]. The optimum pH value of DyPs is acidic [276]. DyPs activity was assayed by the decolorization of an anthraquinone dye RB19 at 595 nm [275].…”