Non-enzymatic roles of human RAD51 at stalled replication forks

Mason, Jennifer M.; Chan, Yuen‐Ling; Weichselbaum, Ralph; Bishop, Douglas K.

doi:10.1038/s41467-019-12297-0

Cited by 94 publications

(96 citation statements)

References 62 publications

(109 reference statements)

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“…S4C). In addition, the RAD51-II3A mutant that can form nucleoprotein filaments, but not perform strand exchange (40), can also rescue fork protection when overexpressed, whereas the RAD51 T131P mutant that cannot form stable filaments does not ( fig. S4C).…”

Section: Smarcal1 Zranb3 and Hltf Are Not Required For Fork Degradamentioning

confidence: 99%

Two replication fork remodeling pathways generate nuclease substrates for distinct fork protection factors

et al. 2020

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Fork reversal is a common response to replication stress, but it generates a DNA end that is susceptible to degradation. Many fork protection factors block degradation, but how they work remains unclear. Here, we find that 53BP1 protects forks from DNA2-mediated degradation in a cell type–specific manner. Fork protection by 53BP1 reduces S-phase DNA damage and hypersensitivity to replication stress. Unlike BRCA2, FANCD2, and ABRO1 that protect reversed forks generated by SMARCAL1, ZRANB3, and HLTF, 53BP1 protects forks remodeled by FBH1. This property is shared by the fork protection factors FANCA, FANCC, FANCG, BOD1L, and VHL. RAD51 is required to generate the resection substrate in all cases. Unexpectedly, BRCA2 is also required for fork degradation in the FBH1 pathway or when RAD51 activity is partially compromised. We conclude that there are multiple fork protection mechanisms that operate downstream of at least two RAD51-dependent fork remodeling pathways.

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Section: Smarcal1 Zranb3 and Hltf Are Not Required For Fork Degradamentioning

confidence: 99%

Two replication fork remodeling pathways generate nuclease substrates for distinct fork protection factors

et al. 2020

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“…However, stalled RFs quickly attract HR proteins (Nguyen et al 2015 ), and more persistent RF-stalling renders replication completion more and more reliant on HR factors such as RAD51 (Petermann et al 2010 ). This is in large part due to protective functions of various HR factors at stalled RFs that are independent of signature recombination reactions such as homology search and DNA strand invasion mediated by the Rad51-single-stranded DNA (ssDNA) filament (Mason et al 2019 ; Zellweger et al 2015 ). Accordingly, human RAD51 has been shown to promote a process known as RF reversal, which entails the dissociation of the nascent leading and lagging strands from the parental template and their annealing with one another, essentially turning three-way RFs into four-way DNA junctions known as reversed RFs, chicken-foot structures, or Holliday junctions (Fig.…”

Section: Homologous Recombination-dependent Replication Restartmentioning

confidence: 99%

Limiting homologous recombination at stalled replication forks is essential for cell viability: DNA2 to the rescue

et al. 2020

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The disease-associated nuclease–helicase DNA2 has been implicated in DNA end-resection during DNA double-strand break repair, Okazaki fragment processing, and the recovery of stalled DNA replication forks (RFs). Its role in Okazaki fragment processing has been proposed to explain why DNA2 is indispensable for cell survival across organisms. Unexpectedly, we found that DNA2 has an essential role in suppressing homologous recombination (HR)-dependent replication restart at stalled RFs. In the absence of DNA2-mediated RF recovery, excessive HR-restart of stalled RFs results in toxic levels of abortive recombination intermediates that lead to DNA damage-checkpoint activation and terminal cell-cycle arrest. While HR proteins protect and restart stalled RFs to promote faithful genome replication, these findings show how HR-dependent replication restart is actively constrained by DNA2 to ensure cell survival. These new insights disambiguate the effects of DNA2 dysfunction on cell survival, and provide a framework to rationalize the association of DNA2 with cancer and the primordial dwarfism disorder Seckel syndrome based on its role in RF recovery.

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“…However, at a protein-mediated replication fork barrier in Schizosaccharomyces pombe, which causes a much more pronounced stall compared to a CAG-130 repeat, Rad51 is required for relocation to the NPC (K. Kramarz and S. Lambert, personal communication). We did observe a few Rad51 foci co-localized with the CAG-130 tract in the nuclear interior (in 3/94 cells) and short Rad51 filaments will not be visible as a focus (Mason et al, 2019). Thus, the subtleties of the timing and level of Rad51 binding and its effect on relocation could depend on the severity or type of fork collapse.…”

Section: Discussionmentioning

confidence: 81%

Faculty Opinions recommendation of Relocation of collapsed forks to the nuclear pore complex depends on sumoylation of DNA repair proteins and permits rad51 association.

Bielinsky

2020

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature

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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.

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Non-enzymatic roles of human RAD51 at stalled replication forks

Cited by 94 publications

References 62 publications

Two replication fork remodeling pathways generate nuclease substrates for distinct fork protection factors

Two replication fork remodeling pathways generate nuclease substrates for distinct fork protection factors

Limiting homologous recombination at stalled replication forks is essential for cell viability: DNA2 to the rescue

Faculty Opinions recommendation of Relocation of collapsed forks to the nuclear pore complex depends on sumoylation of DNA repair proteins and permits rad51 association.

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