The Saccharomyces recombination protein Tid1p is required for adaptation from G2/M arrest induced by a double-strand break

Abstract

Saccharomyces cells with a single unrepaired double-strand break (DSB) will adapt to checkpoint-mediated G2/M arrest and resume cell cycle progression. The decision to adapt is finely regulated by the extent of single-stranded DNA generated from a DSB. We show that cells lacking the recombination protein Tid1p are unable to adapt, but that this defect is distinct from any role in recombination. As with the adaptation-defective mutations yku70Delta and cdc5-ad, permanent arrest in tid1Delta is bypassed by the deletion of the checkpoint gene RAD9. Permanent arrest of tid1Delta cells is suppressed by the rfa1-t11 mutation in the ssDNA binding complex RPA, similar to yku70Delta, whereas the defect in cdc5-ad is not suppressed. Unlike yku70Delta, tid1Delta does not affect 5'-to-3' degradation of DSB ends. The tid1Delta defect cannot be complemented by overexpressing the homolog Rad54p, nor is it affected in rad51Delta tid1Delta, rad54Delta tid1Delta, or rad52Delta tid1Delta double mutants that prevent essentially all homologous recombination. We suggest that Tid1p participates in monitoring the extent of single-stranded DNA produced by resection of DNA ends in a fashion that is distinct from its role in recombination.

Chromatin assembly factors Asf1 and CAF-1 have overlapping roles in deactivating the DNA damage checkpoint when DNA repair is complete

“…5). On the contrary, 95% tid1⌬ cells were persistent as a dumbbell-shaped cell as late as 48 h, which is a characteristic of adaptation-defective (17). These results show that the CAFs are not required to silence the checkpoint during adaptation, but only when the DSB has been repaired, presumably, because in repaired cells, chromatin must be reestablished at the repaired, intact DNA.…”

“…In both processes, a prominent phenomenon is the disappearance of hyperphosphorylated Rad53, which indicates inactivation of the checkpoint (11,15). Deletions of DNA metabolism proteins such as yKu70, yKu80, and Tid1 (Rdh54), as well as the cdc5-ad mutation, are adaptation defective; deletions of the PP2C phosphatases Ptc2 and Ptc3, casein kinase II, and the helicase Srs2 are defective both in adaptation and recovery (12,(15)(16)(17)(18).…”

Asf1 facilitates dephosphorylation of Rad53 after DNA double-strand break repair

“…While chromatin remodelers such as Fun30, Ino80, the RSC complex, and Rad54 facilitate different HR pathways (Kent et al 2007;Shim et al 2007;Hicks et al 2011;Chen et al 2012;Costelloe et al 2012;Eapen et al 2012;Tsabar and Haber 2013), other chromatin-modifying factors, including Asf1, CAF-1 Rdh54, Ino80, and Swr1, participate in regulating the DNA damage checkpoint (Emili et al 2001;Hu et al 2001;Lee et al 2001;Papamichos-Chronakis et al 2006;Kim and Haber 2009;Tsabar and Haber 2013). Here we show that Asf1 regulates the DNA damage checkpoint by a mechanism separate from its histone chaperone activity.…”

Role ofRAD52Epistasis Group Genes in Homologous Recombination and Double-Strand Break Repair

“…BIR in rad51 diploids requires RAD50 (and presumably MRE11 and XRS2), as well as RAD59 and RDH54. Interestingly, RDH54 is required for checkpoint adaptation; therefore, the requirement in rad51-independent BIR could be due to the failure of cells to adapt (193). Because BIR in rad51 mutants involves the degradation or about 30 kb of DNA from the HO-cut site to a preferred site for BIR, it is possible that the requirement for RAD50 is in DNA degradation rather than in the strand invasion step (218).…”