title: Degradation of Mrc1 promotes recombination-mediated restart of stalled replication forks.
abstract: The DNA replication or S-phase checkpoint monitors the integrity of DNA synthesis. Replication stress or DNA damage triggers fork stalling and checkpoint signaling to activate repair pathways. Recovery from checkpoint activation is critical for cell survival following DNA damage. Recovery from the S-phase checkpoint includes inactivation of checkpoint signaling and restart of stalled replication forks. Previous studies demonstrated that degradation of Mrc1, the Saccharomyces cerevisiae ortholog of human Claspin, is facilitated by the SCFDia2 ubiquitin ligase and is important for cell cycle re-entry after DNA damage-induced S-phase checkpoint activation. Here, we show that degradation of Mrc1 facilitated by the SCFDia2 complex is critical to restart stalled replication forks during checkpoint recovery. Using DNA fiber analysis, we showed that Dia2 functions with the Sgs1 and Mph1 helicases (orthologs of human BLM and FANCM, respectively) in the recombination-mediated fork restart pathway. In addition, Dia2 physically interacts with Sgs1 upon checkpoint activation. Importantly, failure to target Mrc1 for degradation during recovery inhibits Sgs1 chromatin association, but this can be alleviated by induced proteolysis of Mrc1 after checkpoint activation. Together, these studies provide new mechanistic insights into how cells recover from activation of the S-phase checkpoint.
authors.affiliation: Department of Genetics, Cell Biology and Development, 321 Church St. SE, University of Minnesota, Minneapolis, MN 55455 USA.
authors.forename: Indrajit
authors.initials: I
authors.lastname: Chaudhury
authors.affiliation: Department of Genetics, Cell Biology and Development, 321 Church St. SE, University of Minnesota, Minneapolis, MN 55455 USA.
authors.forename: Deanna M
authors.initials: DM
authors.lastname: Koepp
mesh_terms: D059447:Cell Cycle Checkpoints; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004261:DNA Replication; D044783:F-Box Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D000072417:Protein Domains; D053484:RecQ Helicases / Q000378:metabolism* / Q000502:physiology; D011995:Recombination, Genetic; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; C495983:Dia2 protein, S cerevisiae; D044783:F-Box Proteins; C441579:MRC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; C491240:MPH1 protein, S cerevisiae; C090472:SGS1 protein, S cerevisiae; D053484:RecQ Helicases; D053487:DEAD-box RNA Helicases