title: The arrestin-like protein ArtA is essential for ubiquitination and endocytosis of the UapA transporter in response to both broad-range and specific signals.
abstract: We investigated the role of all arrestin-like proteins of Aspergillus nidulans in respect to growth, morphology, sensitivity to drugs and specifically for the endocytosis and turnover of the uric acid-xanthine transporter UapA. A single arrestin-like protein, ArtA, is essential for HulA(Rsp) (5) -dependent ubiquitination and endocytosis of UapA in response to ammonium or substrates. Mutational analysis showed that residues 545-563 of the UapA C-terminal region are required for efficient UapA endocytosis, whereas the N-terminal region (residues 2-123) and both PPxY motives are essential for ArtA function. We further show that ArtA undergoes HulA-dependent ubiquitination at residue Lys-343 and that this modification is critical for UapA ubiquitination and endocytosis. Lastly, we show that ArtA is essential for vacuolar turnover of transporters specific for purines (AzgA) or l-proline (PrnB), but not for an aspartate/glutamate transporter (AgtA). Our results are discussed within the frame of recently proposed mechanisms on how arrestin-like proteins are activated and recruited for ubiquitination of transporters in response to broad range signals, but also put the basis for understanding how arrestin-like proteins, such as ArtA, regulate the turnover of a specific transporter in the presence of its substrates.
authors.affiliation: Faculty of Biology, University of Athens, Panepistimiopolis 15784, Athens, Greece.
authors.forename: Mayia
authors.initials: M
authors.lastname: Karachaliou
authors.forename: Sotiris
authors.initials: S
authors.lastname: Amillis
authors.forename: Minoas
authors.initials: M
authors.lastname: Evangelinos
authors.forename: Alexandros C
authors.initials: AC
authors.lastname: Kokotos
authors.forename: Vassilis
authors.initials: V
authors.lastname: Yalelis
authors.forename: George
authors.initials: G
authors.lastname: Diallinas
mesh_terms: D019393:Arrestin / Q000235:genetics / Q000378:metabolism*; D001233:Aspergillus nidulans / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D004252:DNA Mutational Analysis; D004705:Endocytosis / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D011392:Proline / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D011687:Purines / Q000378:metabolism; D013379:Substrate Specificity; D054875:Ubiquitination / Q000502:physiology; D014617:Vacuoles / Q000378:metabolism
chemical_list: D019393:Arrestin; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D011687:Purines; C083852:UAPA protein, Aspergillus nidulans; D011392:Proline