PMID:22333918

Citation	Oler, AJ and Cairns, BR (2012) PP4 dephosphorylates Maf1 to couple multiple stress conditions to RNA polymerase III repression. EMBO J. 31:1440-52
Abstract	Maf1 is the 'master' repressor of RNA polymerase III (Pol III) transcription in yeast, and is conserved in eukaryotes. Maf1 is a phospho-integrator, with unfavourable growth conditions leading to rapid Maf1 dephosphorylation, nuclear accumulation, binding to RNA Pol III at Pol III genes and transcriptional repression. Here, we establish the protein phosphatase 4 (PP4) complex as the main Maf1 phosphatase, and define the involved catalytic (Pph3), scaffold (Psy2) and regulatory subunits (Rrd1, Tip41), as well as uninvolved subunits (Psy4, Rrd2). Multiple approaches support a central role for PP4 in Maf1 dephosphorylation, Maf1 nuclear localization and the rapid repression of Pol III in the nucleus. PP4 action is likely direct, as a portion of PP4 co-precipitates with Maf1, and purified PP4 dephosphorylates Maf1 in vitro. Furthermore, Pph3 mediates (either largely or fully) rapid Maf1 dephosphorylation in response to diverse stresses, suggesting PP4 plays a key role in the integration of cell nutrition and stress conditions by Maf1 to enable Pol III regulation.
Links	PubMed PMC3321174 Online version:10.1038/emboj.2011.501
Keywords	Cell Nucleus/metabolism; Intracellular Signaling Peptides and Proteins/metabolism; Nuclear Proteins/metabolism; Peptidylprolyl Isomerase/metabolism; Phosphoprotein Phosphatases/metabolism; Phosphorylation; RNA Polymerase III/metabolism; Recombinant Fusion Proteins/metabolism; Saccharomyces cerevisiae Proteins/metabolism; Transcription Factors/metabolism; Transcription, Genetic/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
YEAST:PP4R3		GO:0005634: nucleus	ECO:0000314:		C		GFP tagged Psy2 was found to localize strongly in the nucleus (Figure 6C).	complete CACAO 12196
YEAST:PP4C		GO:0006470: protein dephosphorylation	ECO:0000314:		P		Figure 6D.	complete CACAO 12197

References

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