Local regulation of the Srs2 helicase by the SUMO-like domain protein Esc2 promotes recombination at sites of stalled replication

Abstract

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 domain-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 suboptimal 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 and globally prevented at undamaged replicating chromosomes.

Nup358 binds to AGO proteins through its SUMO ‐interacting motifs and promotes the association of target mRNA with miRISC

“…The finding that AGO proteins bind to SIM raised the possibility that AGO has SUMO-like domains found to be present in a few proteins [72,73]. However, analysis suggested that such domains are absent in AGO proteins.…”

Multifunctional Roles of Saccharomyces cerevisiae Srs2 protein in Replication, Recombination and Repair

“…With the demonstration of the strippase activity, many of the phenotypes of srs2 mutants could be interpreted as a failure to prevent homologous recombination (HR), during both repair and rescue of stalled replication forks (Barbour and Xiao 2003;Watts 2006;Lambert et al 2010) and in other instances of mitotic HR (Robert et al 2006;Le Breton et al 2008;Burgess et al 2009;Kerrest et al 2009;Urulangodi et al 2015). The DNA helicase unwinding activity in vivo was demonstrated to be necessary to counteract the deleterious consequences of trinucleotide repeat sequences that could form stable hairpin structures during replication Lahue 2004, 2005;Kerrest et al 2009) and in unwinding at lesion sites produced by cleavage at rNMP residues in DNA to limit mutagenesis (Potenski et al 2014).…”

SUMO-mediated global and local control of recombination

“…7 Mechanistically, we found that Esc2 preferentially binds structures arising at stalled and damaged replication forks. In this environment, Esc2 engages via its SLDs in regulatory interactions with SIM-containing replisome-associated proteins.…”

“…3,4 Our recent findings identified a mechanism that guides recombination specifically at sites of replication stress, by opposing Srs2 accumulation. 7 This newly identified mechanism is also SUMO-orchestrated, involving SIM/SLD interactions between the SIM motifs of Srs2 and STUbL components and the SLDs of Esc2. Our results indicate that the SLD/SIMcoordinated regulatory mechanism acts to locally curb down the anti-recombination effect caused by SUMOylated PCNA, enabling recombination-mediated DDT at sites of replication stress (Fig.…”

“…Although Srs2 is SUMOylated and this modification can occur in the absence of Esc2, we identified Esc2 to be a crucial regulator of Srs2 turnover. 7 Esc2 role in Srs2 turnover relies on its ability to robustly bind stalled forks and on its SLDs-mediated interaction with the SIMs of Slx5 and Srs2. We thus propose that SLDs of Esc2 act as a platform to recruit Slx5-Slx8 to its substrates at stalled forks, and possibly in other chromosomal contexts in which Esc2 functions are important.…”