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    Author(s): Luis F. Larrondo; Loreto Salas; Francisco Melo; Rafael Vicuna; Daniel Cullen
    Date: 2003
    Source: Applied and environmental microbiology. Vol. 69, no. 10 (Oct. 2003): Pages 6257-6263
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (943 KB)

    Description

    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 mco1, 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 Fe 2+ , with a Km close to 2 ┬ÁM. 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.

    Publication Notes

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    Citation

    Larrondo, Luis F.; Salas, Loreto; Melo, Francisco; Vicuna, Rafael; Cullen, Daniel 2003. A novel extracellular multicopper oxidase from Phanerochaete chrysosporium with ferroxidase activity. Applied and environmental microbiology. Vol. 69, no. 10 (Oct. 2003): Pages 6257-6263

    Keywords

    Phanerochaete chrysosporium, white rot, lignin degradation, extracellular multicopper oxidase, ferroxidase activity

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