Saeko Tsuda

Kyoto University, Kioto, Kyōto, Japan

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Publications (3)5.88 Total impact

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    ABSTRACT: Ceriporiopsis subvermispora, a white-rot fungus, is characterized as one of the best biopulping fungi because it can degrade lignin selectively without serious damage to cellulose. We previously demonstrated that during the early stage of wood decay, this fungus produces large amounts of linoleic acid (18:2n-6) and degrades lignin by manganese peroxidase-catalyzed lipid peroxidation. In this study, we cloned a Delta12-fatty acid desaturase gene absolutely essential for the biosynthesis of linoleic acid as the main substrate for lipid peroxidation. This gene designated Cs-fad2 encodes a protein with three histidine-rich domains and four membrane-spanning domains characteristic of other Delta12-fatty acid desaturases. Moreover, we heterologously expressed Cs-fad2 in Saccharomyces cerevisiae lacking Delta12-fatty acid desaturase, and detected the de novo biosynthesis of linoleic acid by gas chromatography-mass spectrometry analysis. We also investigated transcription of Cs-fad2 under various conditions. The transcription was activated and repressed in the presence of a lignin fragment and exogenous fatty acids, respectively. These results may shed light on the molecular relationship between fatty acid metabolism and selective lignin degradation in C. subvermispora.
    Applied Microbiology and Biotechnology 02/2010; 87(1):215-24. DOI:10.1007/s00253-010-2438-1 · 3.34 Impact Factor
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    ABSTRACT: Ceriporic acids are a class of alk(en)ylitaconic acids produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora. Their structural units have similarity with biologically important lichen acids, such as chaetomellic and protolichesterinic acids. The unique function of alkylitaconic acid is the redox silencing of the Fenton reaction system by inhibiting reduction of Fe(3+). As estimated by the catalytic function of Delta9-desaturases, 7-hexadecenyl derivatives bearing a trans configuration have not been reported in the family of alk(en)ylitaconic acids, i.e. the structurally similar lichen acids-alk(en)ylcitraconic and paraconic acids. In this paper, we discuss the isolation of an itaconic acid derivative with an (E)-7-hexadecenyl chain from cultures of C. subvermispora. To identify the natural metabolite, (E)- and (Z)-7-hexadecenylitaconic acids were chemically synthesised. The isolated metabolite was identical to the synthetic (E)-hexadecenylitaconic acid and was designated as ceriporic acid D. Administration of (13)C-[U]-glucose demonstrated that ceriporic acid C and trans-7-hexadecenylitaconic acid (ceriporic acid D) were biosynthesised de novo by C. subvermispora.
    Phytochemistry 11/2008; 69(14):2593-602. DOI:10.1016/j.phytochem.2008.07.014 · 2.55 Impact Factor
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