Translesion DNA synthesis (TLS) functions as a tolerance mechanism for DNA damage at a potentially mutagenic cost. Three TLS polymerases (Pols) function to bypass DNA damage in Saccharomyces cerevisiae: Rev1, Pol zeta, a heterodimer of the Rev3 and Rev7 proteins, and Pol eta (Rad30). Our lab has shown that S. cerevisiae Rev1 protein levels are under striking cell cycle regulation, being approximately 50-fold higher during G2/M than during G1 and much of S phase (Waters and Walker, 2006). REV1 transcript levels only vary approximately 3-fold in a similar cell cycle pattern, suggesting a posttranscriptional mechanism controls protein levels. Here, we show that the S. cerevisiae Rev1 protein is unstable during both the G1 and the G2/M phases of the cell cycle, however, the protein's half-life is shorter in G1 arrested cells than in G2/M arrested cells, indicating that the rate of proteolysis strongly contributes to Rev1's cell cycle regulation. In the presence of the proteasome inhibitor, MG132, the steady-state levels and half-life of Rev1 increase during G1 and G2/M. Through the use of a viable proteasome mutant, we confirm that the levels of Rev1 protein are dependent on proteasome-mediated degradation. The accumulation of higher migrating forms of Rev1 under certain conditions shows that the degradation of Rev1 is possibly directed through the addition of a polyubiquitination signal or another modification. These results support a model that proteasomal degradation acts as a regulatory system of mutagenic TLS mediated by Rev1.CI - Copyright A(c) 2010 Elsevier B.V. All rights reserved.
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|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|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||Conditions||Strain||Source||Reference|