PP2A, a central Tor pathway phosphatase consisting of a catalytic subunit (Pph21 or Pph22), a scaffold subunit (Tpd3) and one of two regulatory subunits (Cdc55 or Rts1) has been repeatedly shown to play important roles in cytoplasmically-localized signal transduction activities. In contrast, its involvement in intra-nuclear control of messenger RNA production has heretofore not been reported. Here, we demonstrate for the first time that binding of the Nitrogen Catabolite Repression-responsive GATA transcription activators (Gln3 & Gat1) to the DAL5 promoter and DAL5 expression require Pph21/22-Tpd3-Cdc55/Rts1 in rapamycin-treated glutamine-grown cells. This conclusion is supported by the following observations: (i) Rapamycin-induced DAL5 expression along with Gln3 and Gat1 binding to the DAL5 promoter fail to occur in pph21Deltapph22Delta, tpd3Delta, and cdc55Deltarts1Delta mutants. (ii) The Pph21/22 requirement persists even when Gat1 and Gln3 are rendered constitutively nuclear thus dissociating the intra-nuclear requirement of PP2A from its partial requirement for rapamycin-induced nuclear Gat1 localization. (iii) Pph21-Myc(13) weakly associates with the DAL5 promoter in a Gat1-dependent manner, whereas similar Pph22-Myc(13) association requires both Gln3 and Gat1. Finally, we demonstrate that a pph21Deltapph22Delta is epistatic to ure2Delta for nuclear Gat1 localization in untreated glutamine-grown cells, whereas for Gln3 just the opposite occurs, i.e., the ure2Delta is epistatic to a pph21Deltapph22Delta. This final observation adds additional support to our previous conclusion that the Gln3 and Gat1 GATA factor localizations are predominantly controlled by different regulatory pathways.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|