Hisamori, Hiromichi

Kyoto University Research Information Repository

Title Effects of copper on oxalate biosynthesis in the brown-rotfungus Fomitopsis palustrisAuthor(s)Hi amori, HiromichiCitationSustainable humanosphere : bulletin of Research Institute forSustainable Humanosphere Kyoto University (2013), 8: 31-31Issue Date2013-02-01URL http://hdl.handle.net/2433/182593RightType Departmental Bulletin PaperTextversionpublisherKyoto University ABSTRACTS (MASTER THESIS) Effects of copper on oxalate biosynthesis  in the brown-rot fungus Fomitopsis palustris  (Graduate School of Agriculture, Laboratory of Metabolic Science of Forest Plants and Microorganisms, RISH, Kyoto University)  Hiromichi Hisamori Wood-rotting basidiomycetes cause severe damage on wooden structures. To protect the wooden structures from the wood-rotting fungi, copper-containing wood preservatives have been used. However, many species of wood-rotting brown-rot fungi can degrade even the wood materials treated with the copper-containing preservatives, by which these wood-rotting fungi are called copper-tolerant fungi. The copper-tolerant ability has been recognized as being associated primarily with oxalic acid excretion, in which oxalic acid produced by copper-tolerant fungi reacts with copper in wood to form insoluble, bio-unavailable inert forms.  From a viewpoint of wood protection from the fungal degradation, the copper-tolerance of these wood-rotting fungi should be diminished. At the same time, the copper-tolerant wood-rotting fungi are promising to be used for bioremediation of wastes of woods treated with copper-containing preservatives [1]. Therefore, it is important to elucidate effects of copper on oxalate biosynthesis to develop bioremediation of copper from wood waste containing wood preservatives including copper.  Brown-rot fungus Fomitopsis palustris possesses two metabolic pathways for oxalate biosynthesis: one is hydrolysis of oxaloacetate catalyzed by oxaloacetate acetylhydrolase (Fomitopsis palustris oxaloacetate acetylhydrolase, FpOAH) in cytosol and the other is dehydrogenation of glyoxylate catalyzed by cytochrome c dependent glyoxylate dehydrogenase (Fomitopsis palustris glyoxylate dehydrogenase, FpGLOXDH) in peroxisome [2-4].  This author investigated effects of Cu2+ on oxalate biosynthesis including expressions of FpOAH and FpGLOXDH. In the absence of Cu2+, amounts of FpOAH transcripts were 22 – 140 times greater than those of FpGLOXDH. The results suggest that FpOAH plays the more significant role than FpGLOXDH and the pathway including FpOAH as a key enzyme is a major pathway for oxalate biosynthesis, supporting our proposed idea that oxalate is biosynthesized mainly in the cytosol by FpOAH but not in the peroxisome by FpGLOXDH [2-4]. On the other hand, under the condition in the presence of Cu2+ an amount of FpOAH transcript was 19.4 times greater on day 4 (minimal magnitude) and 151.1 times greater on day 9 (maximal magnitude) than those of FpGLOXDH. The results suggest that FpOAH also plays a major role in oxalate biosynthesis regardless of absence or presence of Cu2+.  However, the amounts of FpOAH and FpGLOXDH transcripts increased 2.2 and 7 times as their maximal rates by the presence of Cu2+. The results indicate that Cu2+ increased expressions of FpOAH and FpGLOXDH, but the rates of the increments are suggested to be just several times.  References [1] Kartal, S., and Imamura, Y. (2003) “Chemical and biological remediation of CCA-treated waste wood”, Wood Research 90, 111-115. [2] Munir, E., Yoon, J. J., Tokimatsu, T., Hattori, T., and Shimada, M. (2001) “A physiological role for oxalic acid biosynthesis in the wood-rotting basidiomycete Fomitopsis palustris”, PNAS 98:11126-11130. [3] Hattori, T., Okawa, K., Fujimura, M., Mizoguchi, M., Watanabe, T., Tokimatsu, T., Inui, H., Baba, K., Suzuki, S., Umezawa, T., and Shimda, M. (2007) “Subcellular localization of the oxalic acid-producing enzyme, cytochrome c-dependent glyoxylate dehydrogenase in brown-rot fungus Fomitopsis palustris”, Cellullose Chemistry and Technology, 41: 545-553. [4] Sakai, S., Nishide, T., Munir, E., Baba, K., Inui, H., Nakano, Y., Hattori, T. and Shimada. M. (2006) “Subcellular localization of glyoxylate cycle key enzymes involved in oxalate biosynthesis of wood-destroying basidiomycete Fomitopsis palustris grown on glucose”, Microbiology, 152: 1857-1866. 31Sustainable Humanosphere, vol. 8, p.31, 2012

Effects of copper on oxalate biosynthesis in the brown-rot fungus Fomitopsis palustris

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Effects of copper on oxalate biosynthesis in the brown-rot fungus Fomitopsis palustris

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