Hydroxyurea-stalled replication forks become progressively inactivated and require two different RAD51-mediated pathways for restart and repair.
Faithful DNA replication is essential to all life. Hydroxyurea (HU) depletes the cells of dNTPs, which initially results in stalled replication forks that, after prolonged treatment, collapse into DSBs. Here, we report that stalled replication forks are efficiently restarted in a RAD51-dependent process that does not trigger homologous recombination (HR). The XRCC3 protein, which is required for RAD51 foci formation, is also required for replication restart of HU-stalled forks, suggesting that RAD51-mediated strand invasion supports fork restart. In contrast, replication forks collapsed by prolonged replication blocks do not restart, and global replication is rescued by new origin firing. We find that RAD51-dependent HR is triggered for repair of collapsed replication forks, without apparent restart. In conclusion, our data suggest that restart of stalled replication forks and HR repair of collapsed replication forks require two distinct RAD51-mediated pathways.
Petermann
Eva
E
Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford OX3 7DQ, UK.
Orta
Manuel Luís
ML
Issaeva
Natalia
N
Schultz
Niklas
N
Helleday
Thomas
T
D045744:Cell Line, Tumor; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006918:Hydroxyurea / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism*; D016196:S Phase; D013379:Substrate Specificity
D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; C110901:X-ray repair cross complementing protein 3; D004247:DNA; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D006918:Hydroxyurea