Skip to Main Content
Due to a lapse in federal funding, this USDA website will not be actively updated. Once funding has been reestablished, online operations will continue.
Laccase and its role in production of extracellular reactive oxygen species during wood decay by the brown rot basidiomycete Postia placentaAuthor(s): Dongsheng Wei; Carl J. Houtman; Alexander N. Kapich; Christopher G. Hunt; Daniel Cullen; Kenneth E. Hammel
Source: Applied and environmental microbiology. Vol. 76, no. 7 (Apr. 2010): pages 2091-2097.
Publication Series: Miscellaneous Publication
View PDF (330.95 KB)
DescriptionBrown rot basidiomycetes initiate wood decay by producing extracellular reactive oxygen species that depolymerize the structural polysaccharides of lignocellulose. Secreted fungal hydroquinones are considered one contributor because they have been shown to reduce Fe3+, thus generating perhydroxyl radicals and Fe2+, which subsequently react further to produce biodegradative hydroxyl radicals. However, many brown rot fungi also secrete high levels of oxalate, which chelates Fe3+ tightly, making it unreactive with hydroquinones. For hydroquinone-driven hydroxyl radical production to contribute in this environment, an alternative mechanism to oxidize hydroquinones is required. We show here that aspen wood undergoing decay by the oxalate producer Postia placenta contained both 2,5-dimethoxyhydroquinone and laccase activity. Mass spectrometric analysis of proteins extracted from the wood identified a putative laccase (Joint Genome Institute P. placenta protein identification number 111314), and heterologous expression of the corresponding gene confirmed this assignment. Ultrafiltration experiments with liquid pressed from the biodegrading wood showed that a highmolecular-weight component was required for it to oxidize 2,5-dimethoxyhydroquinone rapidly and that this component was replaceable by P. placenta laccase. The purified laccase oxidized 2,5-dimethoxyhydroquinone with a second-order rate constant near 104 M-1s-1, and measurements of the H2O2 produced indicated that approximately one perhydroxyl radical was generated per hydroquinone supplied. Using these values and a previously developed computer model, we estimate that the quantity of reactive oxygen species produced by P. placenta laccase in wood is large enough that it likely contributes to incipient decay.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationWei, Dongsheng; Houtman, Carl J.; Kapich, Alexander N.; Hunt, Christopher G.; Cullen, Daniel; Hammel, Kenneth E. 2010. Laccase and its role in production of extracellular reactive oxygen species during wood decay by the brown rot basidiomycete Postia placenta. Applied and Environmental Microbiology. 76(7): 2091-2097.
KeywordsWood-decaying fungi, brown rot, fungi, biotechnology, lignocellulose, industrial applications, genetics, molecular genetics, biodegradation, Basidiomycetes, hydroquinone, cellulose, laccase, lignin, oxygen, chemical reactions, polysaccharides, aspen, gene expression, oxalates, mass spectrometry, genomes, enzymes, hydrogen peroxide, decay fungi, wood decay, Postia placenta
- Fungal hydroquinones contribute to brown rot of wood
- A comparative genomic analysis of the oxidative enzymes potentially involved in lignin degradation by Agaricus bisporus
- Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion
XML: View XML