title: Tor pathway control of the nitrogen-responsive DAL5 gene bifurcates at the level of Gln3 and Gat1 regulation in Saccharomyces cerevisiae.
abstract: The Tor1,2 protein kinases globally influence many cellular processes including nitrogen-responsive gene expression that correlates with intracellular localization of GATA transcription activators Gln3 and Gat1/Nil1. Gln3-Myc(13) and Gat1-Myc(13) are restricted to the cytoplasm of cells provided with good nitrogen sources, e.g. glutamine. Following the addition of the Tor1,2 inhibitor, rapamycin, both transcription factors relocate to the nucleus. Gln3-Myc(13) localization is highly dependent upon Ure2 and type 2A-related phosphatase, Sit4. Ure2 is required for Gln3 to be restricted to the cytoplasm of cells provided with good nitrogen sources, and Sit4 is required for its location to the nucleus following rapamycin treatment. The paucity of analogous information concerning Gat1 regulation prompted us to investigate the effects of deleting SIT4 and URE2 on Gat1-Myc(13) localization, DNA binding, and NCR-sensitive transcription. Our data demonstrate that Tor pathway control of NCR-responsive transcription bifurcates at the regulation of Gln3 and Gat1. Gat1-Myc(13) localization is not strongly influenced by deleting URE2, nor is its nuclear targeting following rapamycin treatment strongly dependent on Sit4. ChIP experiments demonstrated that Gat1-Myc(13) can bind to the DAL5 promoter in the absence of Gln3. Gln3-Myc(13), on the other hand, cannot bind to DAL5 in the absence of Gat1. We conclude that: (i) Tor pathway regulation of Gat1 differs markedly from that of Gln3, (ii) nuclear targeting of Gln3-Myc(13) is alone insufficient for its recruitment to the DAL5 promoter, and (iii) the Tor pathway continues to play an important regulatory role in NCR-sensitive transcription even after Gln3-Myc(13) is localized to the nucleus.
authors.affiliation: Institut de Recherches Microbiologiques J.-M. Wiame, Laboratoire de Microbiologie Université Libre de Bruxelles, B1070 Brussels, Belgium.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Georis
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Tate
authors.forename: Terrance G
authors.initials: TG
authors.lastname: Cooper
authors.forename: Evelyne
authors.initials: E
authors.lastname: Dubois
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000935:Antifungal Agents / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D050980:GATA Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects / Q000502:physiology*; D005973:Glutamine / Q000235:genetics / Q000378:metabolism; D005979:Glutathione Peroxidase; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D011328:Prions / Q000235:genetics / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D020123:Sirolimus / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology
chemical_list: D000935:Antifungal Agents; D018797:Cell Cycle Proteins; D050980:GATA Transcription Factors; D005973:Glutamine; D005979:Glutathione Peroxidase; D026901:Membrane Transport Proteins; D009584:Nitrogen; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011328:Prions; D054648:Protein Phosphatase 2; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D020123:Sirolimus; D014157:Transcription Factors; C503299:DAL5 protein, S cerevisiae; C096100:GAT1 protein, S cerevisiae; C071664:GLN3 protein, S cerevisiae; C067020:URE2 protein, S cerevisiae; C083324:TOR1 protein, S cerevisiae; C081135:TOR2 protein, S cerevisiae; C104343:SIT4 protein, S cerevisiae