The Saccharomyces cerevisiae Esc2 and Smc5-6 proteins promote sister chromatid junction-mediated intra-S repair.

Abstract:: Recombination is important for DNA repair, but it can also contribute to genome rearrangements. RecQ helicases, including yeast Sgsl and human BLM, safeguard genome integrity through their functions in DNA recombination. Sgsl prevents the accumulation of Rad51-dependent sister chromatid junctions at damaged replication forks, and its functionality seems to be regulated by Ubc9-and Mms21-dependent sumoylation. We show that mutations in Smc5-6 and Esc2 also lead to an accumulation of recombinogenic structures at damaged replication forks. Because Smc5-6 is sumoylated in an Mms21-dependent manner, this finding suggests that Smc5-6 may be a crucial target of Mms21 implicated in this process. Our data reveal that Smc5-6 and Esc2 are required to tolerate DNA damage and that their functionality is critical in genotoxic conditions in the absence of Sgsl. As reported previously for Sgsl and Smc5-6, we find that Esc2 physically interacts with Ubc9 and SUMO. This interaction is correlated with the ability of Esc2 to promote DNA damage tolerance. Collectively, these data suggest that Esc2 and Smc5-6 act in concert with Sgsl to prevent the accumulation of recombinogenic structures at damaged replication forks, likely by integrating sumoylation activities to regulate the repair pathways in response to damaged DNA. © 2009 by The American Society for Cell Biology.

Authors:: J Sollier, R Driscoll, F Castellucci, M Foiani, SP Jackson, D Branzei

Themes