title: Molecular characterization of two ammonium transporters from the ectomycorrhizal fungus Hebeloma cylindrosporum.
abstract: Heterologous expression of the yeast triple Mep mutant has enabled the first molecular characterization of AMT/MEP family members in an ectomycorrhizal fungus. External hyphae, which play a key role in nitrogen nutrition of trees, are considered as the absorbing structure of the ectomycorrhizal symbiosis and therefore molecular studies on ammonium transport in hyphae are urgently needed. The kinetic properties of AMT2 and AMT3 from Hebeloma cylindrosporum were studied in Saccharomyces cerevisiae. Expression of HcAmts in the yeast triple Mep mutant restored ammonium retention within cells. The HcAmts did not complement the ammonium sensing defect phenotype of Mep2Delta cells during pseudohyphal differentiation. Northern blot analysis in H. cylindrosporum showed that the HcAMTs were up-regulated upon nitrogen deprivation and down-regulated by ammonium.
authors.affiliation: Université Henri Poincaré, Nancy I, UMR INRA/UHP 1136 Interactions Arbres Micro-organismes, Vandoeuvre-les-Nancy, France.
authors.forename: A
authors.initials: A
authors.lastname: Javelle
authors.forename: B R
authors.initials: BR
authors.lastname: Rodríguez-Pastrana
authors.forename: C
authors.initials: C
authors.lastname: Jacob
authors.forename: B
authors.initials: B
authors.lastname: Botton
authors.forename: A
authors.initials: A
authors.lastname: Brun
authors.forename: B
authors.initials: B
authors.lastname: André
authors.forename: A M
authors.initials: AM
authors.lastname: Marini
authors.forename: M
authors.initials: M
authors.lastname: Chalot
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001483:Base Sequence; D001487:Basidiomycota / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D017931:DNA Primers; D015966:Gene Expression Regulation, Fungal; D007700:Kinetics; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D020033:Protein Isoforms; D000641:Ammonia