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Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion

Author(s):

Diego Martinez
Jean Challacombe
Ingo Morgenstern
David Hibbett
Monika Schmoll
Christian P. Kubicek
Patricia Ferreira
Francisco J. Ruiz-Duenas
Angel T. Martinez

Year:

2009

Publication type:

Miscellaneous Publication

Primary Station(s):

Forest Products Laboratory

Source:

Proceedings of the National Academy of Sciences of the USA. Vol. 106, no. 6 (Feb. 10, 2009).

Description

Brown-rot fungi such as Postia placenta are common inhabitants of forest ecosystems and are also largely responsible for the destructive decay of wooden structures. Rapid depolymerization of cellulose is a distinguishing feature of brown-rot, but the biochemical mechanisms and underlying genetics are poorly understood. Systematic examination of the P. placenta genome, transcriptome, and secretome revealed unique extracellular enzyme systems, including an unusual repertoire of extracellular glycoside hydrolases. Genes encoding exocellobiohydrolases and cellulose-binding domains, typical of cellulolytic microbes, are absent in this efficient cellulose-degrading fungus. When P. placenta was grown in medium containing cellulose as sole carbon source, transcripts corresponding to many hemicellulases and to a single putative [Beta]-1–4 endoglucanase were expressed at high levels relative to glucose-grown cultures. These transcript profiles were confirmed by direct identification of peptides by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Also upregulated during growth on cellulose medium were putative iron reductases, quinone reductase, and structurally divergent oxidases potentially involved in extracellular generation of Fe(II) and H2O2. These observations are consistent with a biodegradative role for Fenton chemistry in which Fe(II) and H2O2 react to form hydroxyl radicals, highly reactive oxidants capable of depolymerizing cellulose. The P. placenta genome resources provide unparalleled opportunities for investigating such unusual mechanisms of cellulose conversion. More broadly, the genome offers insight into the diversification of lignocellulose degrading mechanisms in fungi. Comparisons with the closely related white-rot fungus Phanerochaete chrysosporium support an evolutionary shift from white-rot to brown-rot during which the capacity for efficient depolymerization of lignin was lost.

Citation

Martinez, Diego; Challacombe, Jean; Morgenstern, Ingo; Hibbett, David; Schmoll, Monika; Kubicek, Christian P.; Ferreira, Patricia; Ruiz-Duenas, Francisco J.; Martinez, Angel T.; Kersten, Philip J.; Hammel, Kenneth E.; Gaskell, Jill A.; Cullen, Daniel. 2009. Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion. Proceedings of the National Academy of Sciences of the USA. Vol. 106, no. 6 (Feb. 10, 2009): pages 1954-1959. (Supporting information online at: http://www.pnas.org/content/106/6/1954/suppl/DCSupplemental )

Cited

Publication Notes

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  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
https://www.fs.usda.gov/treesearch/pubs/34240