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Per Persson. Photo.

Per Persson

Director

Per Persson. Photo.

Nitrogen acquisition from mineral-associated proteins by an ectomycorrhizal fungus

Author

  • Tao Wang
  • Zhaomo Tian
  • Anders Tunlid
  • Per Persson

Summary, in English

In nitrogen (N)-limited boreal forests, trees depend on the decomposing activity of their ectomycorrhizal (ECM) fungal symbionts to access soil N. A large fraction of this N exists as proteinaceous compounds associated with mineral particles. However, it is not known if ECM fungi can access these mineral-associated proteins; accordingly, possible acquisition mechanisms have not been investigated. With tightly controlled isotopic, spectroscopic, and chromatographic experiments, we quantified and analyzed the mechanisms of N acquisition from iron oxide mineral-associated proteins by Paxillus involutus, a widespread ECM fungus in boreal forests. The fungus acquired N from the mineral-associated proteins. The collective results indicated a proteolytic mechanism involving formation of the crucial enzyme–substrate complexes at the mineral surfaces. Hence, the enzymes hydrolyzed the mineral-associated proteins without initial desorption of the proteins. The proteolytic activity was suppressed by adsorption of proteases to the mineral particles. This process was counteracted by fungal secretion of mineral-surface-reactive compounds that decreased the protease–mineral interactions and thereby promoted the formation of enzyme–substrate complexes. The ability of ECM fungi to simultaneously generate extracellular proteases and surface-reactive metabolites suggests that they can play an important role in unlocking the large N pool of mineral-associated proteins to trees in boreal forests.

Department/s

  • BECC - Biodiversity and Ecosystem services in a Changing Climate
  • Microbial Ecology
  • Centre for Environmental and Climate Science (CEC)

Publishing year

2020-10

Language

English

Pages

697-711

Publication/Series

New Phytologist

Volume

228

Issue

2

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Biochemistry and Molecular Biology

Keywords

  • boreal forests
  • decomposition and N acquisition
  • ectomycorrhizal (ECM) fungi
  • iron oxides
  • mineral-associated organic nitrogen
  • Paxillus involutus
  • secondary metabolites
  • soil proteins

Status

Published

Research group

  • Microbial Ecology

ISBN/ISSN/Other

  • ISSN: 0028-646X