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The molecular components of the extracellular protein-degradation pathways of the ectomycorrhizal fungus Paxillus involutus.

In English

Författare

Summary, in English

Proteins contribute to a major part of the organic nitrogen (N) in forest soils. This N is mobilized and becomes available to trees as a result of the depolymerizing activities of symbiotic ectomycorrhizal fungi. The mechanisms by which these fungi depolymerize proteins and assimilate the released N are poorly characterized. Biochemical analysis and transcriptome profiling were performed to examine the proteolytic machinery and the uptake system of the ectomycorrhizal basidiomycete Paxillus involutus during the assimilation of organic N from various protein sources and extracts of organic matter. All substrates induced secretion of peptidase activity with an acidic pH optimum, mostly contributed by aspartic peptidases. The peptidase activity was transiently repressed by ammonium. Transcriptional analysis revealed a large number of extracellular endo- and exopeptidases. The expression levels of these peptidases were regulated in parallel with transporters and enzymes involved in the assimilation and metabolism of the released peptides and amino acids. For the first time the molecular components of the protein degradation pathways of an ectomycorrhizal fungus are described. The data suggest that the transcripts encoding these components are regulated in response to the chemical properties and the availability of the protein substrates.

Publiceringsår

2013

Språk

Engelska

Sidor

875-887

Publikation/Tidskrift/Serie

New Phytologist

Volym

200

Issue

3

Dokumenttyp

Artikel i tidskrift

Förlag

Wiley-Blackwell

Ämne

  • Ecology

Nyckelord

  • ectomycorrhizal (ECM) fungi
  • nitrogen assimilation
  • nitrogen catabolite repression
  • nitrogen transporters
  • Paxillus involutus
  • peptidases
  • transcriptional regulation.

Status

Published

Forskningsgrupp

  • Microbial Ecology

ISBN/ISSN/Övrigt

  • ISSN: 1469-8137