title: AgtA, the dicarboxylic amino acid transporter of Aspergillus nidulans, is concertedly down-regulated by exquisite sensitivity to nitrogen metabolite repression and ammonium-elicited endocytosis.
abstract: We identified agtA, a gene that encodes the specific dicarboxylic amino acid transporter of Aspergillus nidulans. The deletion of the gene resulted in loss of utilization of aspartate as a nitrogen source and of aspartate uptake, while not completely abolishing glutamate utilization. Kinetic constants showed that AgtA is a high-affinity dicarboxylic amino acid transporter and are in agreement with those determined for a cognate transporter activity identified previously. The gene is extremely sensitive to nitrogen metabolite repression, depends on AreA for its expression, and is seemingly independent from specific induction. We showed that the localization of AgtA in the plasma membrane necessitates the ShrA protein and that an active process elicited by ammonium results in internalization and targeting of AgtA to the vacuole, followed by degradation. Thus, nitrogen metabolite repression and ammonium-promoted vacuolar degradation act in concert to downregulate dicarboxylic amino acid transport activity.
authors.affiliation: Institut de Génétique et Microbiologie, Université Paris-Sud, UMR8621, Orsay, France.
authors.forename: Angeliki
authors.initials: A
authors.lastname: Apostolaki
authors.forename: Zoi
authors.initials: Z
authors.lastname: Erpapazoglou
authors.forename: Laura
authors.initials: L
authors.lastname: Harispe
authors.forename: Maria
authors.initials: M
authors.lastname: Billini
authors.forename: Panagiota
authors.initials: P
authors.lastname: Kafasla
authors.forename: Dimosthenis
authors.initials: D
authors.lastname: Kizis
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Peñalva
authors.forename: Claudio
authors.initials: C
authors.lastname: Scazzocchio
authors.forename: Vicky
authors.initials: V
authors.lastname: Sophianopoulou
mesh_terms: D000595:Amino Acid Sequence; D026905:Amino Acid Transport Systems / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000600:Amino Acids, Dicarboxylic / Q000378:metabolism; D001233:Aspergillus nidulans / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D015536:Down-Regulation; D004705:Endocytosis; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D026905:Amino Acid Transport Systems; D000600:Amino Acids, Dicarboxylic; D005656:Fungal Proteins; D000644:Quaternary Ammonium Compounds; D009584:Nitrogen