Dpb4 promotes resection of DNA double-strand breaks and checkpoint activation by acting in two different protein complexes

AbstractBudding yeast Dpb4 (POLE3/CHRAC17 in mammals) is a highly conserved histone fold protein that is shared by two protein complexes: the chromatin remodeler ISW2/hCHRAC and the DNA polymerase ε (Pol ε) holoenzyme. In Saccharomyces cerevisiae, Dpb4 forms histone-like dimers with Dls1 in the ISW2 complex and with Dpb3 in the Pol ε complex. Here, we show that Dpb4 plays two functions in sensing and processing DNA double-strand breaks (DSBs). Dpb4 promotes histone removal and DSB resection by interacting with Dls1 to facilitate the association of the Isw2 ATPase to DSBs. Furthermore, it promotes checkpoint activation by interacting with Dpb3 to facilitate the association of the checkpoint protein Rad9 to DSBs. Persistence of both Isw2 and Rad9 at DSBs is enhanced by the A62S mutation that is located in the Dpb4 histone fold domain and increases Dpb4 association at DSBs. Thus, Dpb4 exerts two distinct functions at DSBs depending on its interactors.

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DNA polymerases δ and λ cooperate in repairing double-strand breaks by microhomology-mediated end-joining in Saccharomyces cerevisiae

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1507833112 ◽

2015 ◽

Vol 112 (50) ◽

pp. E6907-E6916 ◽

Cited By ~ 16

Author(s):

Damon Meyer ◽

Becky Xu Hua Fu ◽

Wolf-Dietrich Heyer

Keyword(s):

Saccharomyces Cerevisiae ◽

Dna Polymerase ◽

Genome Stability ◽

Double Strand Breaks ◽

Dna Polymerase Delta ◽

Dna Double Strand Breaks ◽

End Joining ◽

Strand Breaks ◽

Repair Efficiency ◽

Repair Pathways

Maintenance of genome stability is carried out by a suite of DNA repair pathways that ensure the repair of damaged DNA and faithful replication of the genome. Of particular importance are the repair pathways, which respond to DNA double-strand breaks (DSBs), and how the efficiency of repair is influenced by sequence homology. In this study, we developed a genetic assay in diploid Saccharomyces cerevisiae cells to analyze DSBs requiring microhomologies for repair, known as microhomology-mediated end-joining (MMEJ). MMEJ repair efficiency increased concomitant with microhomology length and decreased upon introduction of mismatches. The central proteins in homologous recombination (HR), Rad52 and Rad51, suppressed MMEJ in this system, suggesting a competition between HR and MMEJ for the repair of a DSB. Importantly, we found that DNA polymerase delta (Pol δ) is critical for MMEJ, independent of microhomology length and base-pairing continuity. MMEJ recombinants showed evidence that Pol δ proofreading function is active during MMEJ-mediated DSB repair. Furthermore, mutations in Pol δ and DNA polymerase 4 (Pol λ), the DNA polymerase previously implicated in MMEJ, cause a synergistic decrease in MMEJ repair. Pol λ showed faster kinetics associating with MMEJ substrates following DSB induction than Pol δ. The association of Pol δ depended on RAD1, which encodes the flap endonuclease needed to cleave MMEJ intermediates before DNA synthesis. Moreover, Pol δ recruitment was diminished in cells lacking Pol λ. These data suggest cooperative involvement of both polymerases in MMEJ.

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Four-pronged negative feedback of DSB machinery in meiotic DNA-break control in mice

Nucleic Acids Research ◽

10.1093/nar/gkab082 ◽

2021 ◽

Author(s):

Ihsan Dereli ◽

Marcello Stanzione ◽

Fabrizio Olmeda ◽

Frantzeskos Papanikos ◽

Marek Baumann ◽

...

Keyword(s):

Negative Feedback ◽

Protein Complexes ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Homologous Chromosomes ◽

Damage Response ◽

Auxiliary Protein ◽

Genomic Locations ◽

Spatiotemporal Control

Abstract In most taxa, halving of chromosome numbers during meiosis requires that homologous chromosomes (homologues) pair and form crossovers. Crossovers emerge from the recombination-mediated repair of programmed DNA double-strand breaks (DSBs). DSBs are generated by SPO11, whose activity requires auxiliary protein complexes, called pre-DSB recombinosomes. To elucidate the spatiotemporal control of the DSB machinery, we focused on an essential SPO11 auxiliary protein, IHO1, which serves as the main anchor for pre-DSB recombinosomes on chromosome cores, called axes. We discovered that DSBs restrict the DSB machinery by at least four distinct pathways in mice. Firstly, by activating the DNA damage response (DDR) kinase ATM, DSBs restrict pre-DSB recombinosome numbers without affecting IHO1. Secondly, in their vicinity, DSBs trigger IHO1 depletion mainly by another DDR kinase, ATR. Thirdly, DSBs enable homologue synapsis, which promotes the depletion of IHO1 and pre-DSB recombinosomes from synapsed axes. Finally, DSBs and three DDR kinases, ATM, ATR and PRKDC, enable stage-specific depletion of IHO1 from all axes. We hypothesize that these four negative feedback pathways protect genome integrity by ensuring that DSBs form without excess, are well-distributed, and are restricted to genomic locations and prophase stages where DSBs are functional for promoting homologue pairing and crossover formation.

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