Smc5/6 Mediated Sumoylation of the Sgs1-Top3-Rmi1 Complex Promotes Removal of Recombination Intermediates

• Sgs1 interacts with the Smc5/6 SUMO ligase complex
• Smc5/6 promotes STR sumoylation upon recombination intermediate formation
• STR sumoylation aids recombination intermediate removal
• Sumoylation favors STR inter-subunit interactions and accumulation at DNA repair foci

SummaryTimely removal of DNA recombination intermediates is critical for genome stability. The DNA helicase-topoisomerase complex, Sgs1-Top3-Rmi1 (STR), is the major pathway for processing these intermediates to generate conservative products. However, the mechanisms that promote STR-mediated functions remain to be defined. Here we show that Sgs1 binds to poly-SUMO chains and associates with the Smc5/6 SUMO E3 complex in yeast. Moreover, these interactions contribute to the sumoylation of Sgs1, Top3, and Rmi1 upon the generation of recombination structures. We show that reduced STR sumoylation leads to accumulation of recombination structures, and impaired growth in conditions when these structures arise frequently, highlighting the importance of STR sumoylation. Mechanistically, sumoylation promotes STR inter-subunit interactions and accumulation at DNA repair centers. These findings expand the roles of sumoylation and Smc5/6 in genome maintenance by demonstrating that they foster STR functions in the removal of recombination intermediates.

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