Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion
Fecha
2009Autor
Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
Versión publicada / Argitaratu den bertsioa
Impacto
|
10.1073/pnas.0809575106
Resumen
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 secr ...
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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 β -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. [--]
Materias
Postia placenta,
Cellulose,
Fenton,
Lignin,
Cellulase,
Brown-rot
Editor
National Academy of Sciences
Publicado en
PNAS, February 10, 2009 106 (6) 1954-1959
Departamento
Universidad Pública de Navarra. Departamento de Producción Agraria /
Nafarroako Unibertsitate Publikoa. Nekazaritza Ekoizpena Saila
Versión del editor
Entidades Financiadoras
This work was supported by the U.S. Department of Energy’s Office of
Science, Biological and Environmental Research Program, and University of California,
Lawrence Berkeley National Laboratory Contract DE-AC02–05CH11231;
Lawrence Livermore National Laboratory Contract DE-AC52–07NA27344; Los
Alamos National Laboratory Contract DE-AC02–06NA25396; University of Wisconsin
Grant DE-FG02–87ER13712; Forest Products Laboratory, U.S. Department
of Agriculture, Cooperative State Research, Education, and Extension Services
Grant 2007–35504-18257; National Institutes of Health Grant GM060201 (to
University of New Mexico); Centro de Investigaciones Biológicas (Madrid) EUproject
NMP2–2006-026456; Ministry of Education Czech Republic Grant
LC06066.