title: Characterization and regulation of PiDur3, a permease involved in the acquisition of urea by the ectomycorrhizal fungus Paxillus involutus.
abstract: Urea, which is known to be a source of nitrogen for the growth of many organisms, represents an important fertilizer in forest soils. Since most trees form symbiotic associations with ectomycorrhizal fungi, the capacities of these symbionts to take up and assimilate urea would determine the efficiency of urea nitrogen salvaging by plants. We showed that Paxillusinvolutus, an ectomycorrhizal basidiomycete, is capable of using urea as sole nitrogen source. We report the molecular characterization of an active urea transporter (PiDur3) isolated from this fungus. We demonstrated that the import of urea is a minor event on ammonium condition, since the expression of PiDUR3 is repressed by the high intracellular glutamine pool. Interestingly, on urea nutritive condition, the uptake of urea is rather mediated by the intracellular urea pool and particularly by urease efficiency.
authors.affiliation: Faculty of Sciences and Technology, Research Unit INRA/UHP 1136 Tree-microbe Interactions, Nancy-University, BP 239, F54506 Vandoeuvre-les-Nancy Cedex, France. Melanie.Morel@scbiol.uhp-nancy.fr
authors.forename: Mélanie
authors.initials: M
authors.lastname: Morel
authors.forename: Christophe
authors.initials: C
authors.lastname: Jacob
authors.forename: Michael
authors.initials: M
authors.lastname: Fitz
authors.forename: Daniel
authors.initials: D
authors.lastname: Wipf
authors.forename: Michel
authors.initials: M
authors.lastname: Chalot
authors.forename: Annick
authors.initials: A
authors.lastname: Brun
mesh_terms: D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D017672:Nitrogen Compounds / Q000378:metabolism; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014508:Urea / Q000378:metabolism*; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D017672:Nitrogen Compounds; D014508:Urea