Relocation of Collapsed Forks to the Nuclear Pore Complex Depends on Sumoylation of DNA Repair Proteins and Permits Rad51 Association

• Published in: Cell reports (Cambridge) Vol. 31; no. 6; p. 107635
• Main Authors: Whalen, Jenna M., Dhingra, Nalini, Wei, Lei, Zhao, Xiaolan, Freudenreich, Catherine H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.05.2020
• Subjects: CAG repeat; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; DNA Repair; DNA Replication; fork collapse; fork relocation; Nuclear Pore - genetics; Nuclear Pore - metabolism; nuclear pore complex; Rad51 Recombinase - genetics; Rad51 Recombinase - metabolism; Rad52 Rad59 sumoylation; Recombination, Genetic; replication fork; RPA sumoylation; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Smc5-Smc6; SUMO-1 Protein - genetics; SUMO-1 Protein - metabolism; Sumoylation; trinucleotide repeat; Smc5-Smc6; nuclear pore complex; replication fork; Rad52 Rad59 sumoylation; trinucleotide repeat; RPA sumoylation; CAG repeat; fork collapse; fork relocation
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2020.107635

Expanded CAG repeats form stem-loop secondary structures that lead to fork stalling and collapse. Previous work has shown that these collapsed forks relocalize to nuclear pore complexes (NPCs) in late S phase in a manner dependent on replication, the nucleoporin Nup84, and the Slx5 protein, which prevents repeat fragility and instability. Here, we show that binding of the Smc5/6 complex to the collapsed fork triggers Mms21-dependent sumoylation of fork-associated DNA repair proteins, and that RPA, Rad52, and Rad59 are the key sumoylation targets that mediate relocation. The SUMO interacting motifs of Slx5 target collapsed forks to the NPC. Notably, Rad51 foci only co-localize with the repeat after it is anchored to the nuclear periphery and Rad51 exclusion from the early collapsed fork is dependent on RPA sumoylation. This pathway may provide a mechanism to constrain recombination at stalled or collapsed forks until it is required for fork restart. [Display omitted] •Relocation of collapsed forks to NPCs depends on sumoylation by Mms21/Nse2•Targets of sumoylation important for relocation are RPA, Rad52, Rad59, and Smc5•Resection mediated by Mre11, Exo1, and Sgs1 is required for relocation to the NPC•RPA sumoylation prevents Rad51 binding to collapsed forks before NPC anchoring Whalen et al. establish the mechanism by which collapsed forks caused by expanded CAG repeats relocate to the nuclear pore complex to maintain genome stability. This mechanism relies on sumoylation of repair proteins that bind the collapsed fork to facilitate relocation and constrain recombination until at the nuclear pore complex.