Project description:ATP-dependent chromatin remodeling complexes have been shown to participate in DNA replication in addition to transcription and DNA repair. However, the mechanisms of their involvement in DNA replication remain unclear. Here, we reveal a specific function of the yeast INO80 chromatin remodeling complex in the DNA damage tolerance pathways. Whereas INO80 is necessary for the resumption of replication at forks stalled by methyl methane sulfonate (MMS), it is not required for replication fork collapse after treatment with hydroxyurea (HU). Mechanistically, INO80 regulates DNA damage tolerance during replication through modulation of PCNA (proliferating cell nuclear antigen) ubiquitination and Rad51-mediated processing of recombination intermediates at impeded replication forks. Our findings establish a mechanistic link between INO80 and DNA damage tolerance pathways, indicating that chromatin remodeling is important for accurate DNA replication. INO80 distribution in WT cells was measured.
Project description:Schlafen family member 11 (SLFN11) expression sensitizes cells to a spectrum of DNA-damaging chemotherapies. Previous studies have shown that SLFN11 is recruited to stalled replication forks in response to replication stress; however, the role of SLFN11 at stressed replication forks remains unclear. Using single-molecule DNA fiber analysis and super-resolution microscopy to interrogate the dynamics of individual replication forks, we show that SLFN11 acts upon stalled replication forks to suppress efficient fork restart. In the absence of SLFN11 expression, fork restart proceeds through a pathway involving the ubiquitin ligase RFWD3 and the DNA primase-polymerase PRIMPOL to facilitate gapped DNA synthesis. In the absence of SLFN11 expression, this pathway ensures that cells do not accumulate replication-associated DNA damage in response to stalled forks. Collectively, our results provide a mechanistic basis for how SLFN11 can counteract DNA damage tolerance by suppressing the RFWD3-PRIMPOL axis.
The deposit includes the mass spectrometry data files generated from this study.
Project description:DNA replication forks that are stalled by DNA damage activate an S phase checkpoint that prevents irreversible fork arrest and cell death. The increased cell death caused by DNA damage in budding yeast cells lacking the Rad53 checkpoint protein kinase is partially suppressed by deletion of the EXO1 gene. Here,we identified that loss of the histone deacetylase complex Rpd3L promotes survival of rad53∆ cells exposed to DNA damaging agents. From epistasis analysis, we show that this suppression operates in a separate pathway from the previously described suppression by deletion of EXO1.
Project description:ATP-dependent chromatin remodeling complexes have been shown to participate in DNA replication in addition to transcription and DNA repair. However, the mechanisms of their involvement in DNA replication remain unclear. Here, we reveal a specific function of the yeast INO80 chromatin remodeling complex in the DNA damage tolerance pathways. Whereas INO80 is necessary for the resumption of replication at forks stalled by methyl methane sulfonate (MMS), it is not required for replication fork collapse after treatment with hydroxyurea (HU). Mechanistically, INO80 regulates DNA damage tolerance during replication through modulation of PCNA (proliferating cell nuclear antigen) ubiquitination and Rad51-mediated processing of recombination intermediates at impeded replication forks. Our findings establish a mechanistic link between INO80 and DNA damage tolerance pathways, indicating that chromatin remodeling is important for accurate DNA replication.
Project description:Background: Chromatin remodeling complexes facilitate the access of enzymes that mediate transcription, replication or repair of DNA by modulating nucleosome position and/or composition. Ino80 is the DNA-dependent Snf2-like ATPase subunit of a complex whose nucleosome remodeling activity requires actin-related proteins, Arp4, Arp5 and Arp8, as well as two RuvB-like DNA helicase subunits. Budding yeast mutants deficient for Ino80 function are not only hypersensitive to reagents that induce DNA double strand breaks, but also to those that impair replication fork progression. Results: To understand why ino80 mutants are sensitive to agents that perturb DNA replication, we used chromatin immunoprecipitation to map the binding sites of the Ino80 chromatin remodeling complex on four budding yeast chromosomes. We found that Ino80 and Arp5 binding sites coincide with origins of DNA replication and tRNA genes. In addition, Ino80 was bound at 67% of the promoters of genes that are sensitive to ino80 mutation. When replication forks were arrested near origins in the presence of hydroxyurea (HU), the presence of the Ino80 complex at stalled forks and at unfired origins increased dramatically. Importantly, the resumption of DNA replication after release from a HU block was impaired in the absence of Ino80 activity. Mutant cells accumulated double-strand breaks as they attempted to restart replication. Consistently, ino80-deficient cells, although proficient for checkpoint activation, delay recovery from the checkpoint response. Conclusions: The Ino80 chromatin remodeling complex is enriched at stalled replication forks where it promotes the resumption of replication upon recovery from fork arrest. Keywords: ChIP-chip
Project description:Accurate completion of replication relies on the ability of cells to activate error-free recombination-mediated DNA damage-bypass at sites of perturbed replication. However, as anti-recombinase activities are also recruited to replication forks, how recombination-mediated damage-bypass is enabled at replication stress sites remained puzzling. Here we uncovered that the conserved SUMO-like domains-containing Saccharomyces cerevisiae protein, Esc2, facilitates recombination-mediated DNA damage tolerance by allowing optimal recruitment of the Rad51 recombinase specifically at sites of perturbed replication. Mechanistically, Esc2 binds stalled replication forks and counteracts the anti-recombinase Srs2 helicase via a two-faceted mechanism involving chromatin recruitment and turnover of Srs2. Importantly, point mutations in the SUMO-like domains of Esc2 that reduce its interaction with Srs2 cause sub-optimal levels of Rad51 recruitment at damaged replication forks. In conclusion, our results reveal how recombination-mediated DNA damage tolerance is locally enabled at sites of replication stress, while globally prevented at undamaged replicating chromosomes.
Project description:Background: Chromatin remodeling complexes facilitate the access of enzymes that mediate transcription, replication or repair of DNA by modulating nucleosome position and/or composition. Ino80 is the DNA-dependent Snf2-like ATPase subunit of a complex whose nucleosome remodeling activity requires actin-related proteins, Arp4, Arp5 and Arp8, as well as two RuvB-like DNA helicase subunits. Budding yeast mutants deficient for Ino80 function are not only hypersensitive to reagents that induce DNA double strand breaks, but also to those that impair replication fork progression. Results: To understand why ino80 mutants are sensitive to agents that perturb DNA replication, we used chromatin immunoprecipitation to map the binding sites of the Ino80 chromatin remodeling complex on four budding yeast chromosomes. We found that Ino80 and Arp5 binding sites coincide with origins of DNA replication and tRNA genes. In addition, Ino80 was bound at 67% of the promoters of genes that are sensitive to ino80 mutation. When replication forks were arrested near origins in the presence of hydroxyurea (HU), the presence of the Ino80 complex at stalled forks and at unfired origins increased dramatically. Importantly, the resumption of DNA replication after release from a HU block was impaired in the absence of Ino80 activity. Mutant cells accumulated double-strand breaks as they attempted to restart replication. Consistently, ino80-deficient cells, although proficient for checkpoint activation, delay recovery from the checkpoint response. Conclusions: The Ino80 chromatin remodeling complex is enriched at stalled replication forks where it promotes the resumption of replication upon recovery from fork arrest. Keywords: ChIP-chip
Project description:In the yeast Saccharomyces cerevisiae, cleavage factor I (CFI) and cleavage and polyadenylation factor (CPF) build the core of the transcription termination machinery. CFI comprises the Rna14, Rna15, Pcf11, and Clp1 proteins, as well as the associated Hrp5 RNA-binding protein. We found that CFI participates in the DNA damage response and that rna14-1 shows synthetic growth defects with mutants of different repair pathways, including homologous recombination, non-homologous end joining, post replicative repair, mismatch repair, and nucleotide excision repair, implicating that impaired RNAPII termination and 3’-end processing decreases the cellular tolerance for DNA damage. Beyond replication progression defects, we found that bypass of the G1/S checkpoint in rna14-1 cells leads to synthetic sickness, accumulation of phosphorylated H2A, as well as increase in Rad52-foci and in recombination. Our data provide evidence that CFI dysfunction impairs RNAPII turnover, leading to replication hindrance and lower tolerance to exogenous DNA damage. These findings underscore the importance of coordination between transcription termination, DNA repair and replication in the maintenance of genomic stability.