Mre11 complex links sister chromatids to promote repair of a collapsed replication fork.
Collapsed replication forks, which are a major source of DNA double-strand breaks (DSBs), are repaired by sister chromatid recombination (SCR). The Mre11-Rad50-Nbs1 (MRN) protein complex, assisted by CtIP/Sae2/Ctp1, initiates SCR by nucleolytically resecting the single-ended DSB (seDSB) at the collapsed fork. The molecular architecture of the MRN intercomplex, in which ... zinc hooks at the apices of long Rad50 coiled-coils connect two Mre112-Rad502 complexes, suggests that MRN also structurally assists SCR. Here, Rad50 ChIP assays in Schizosaccharomyces pombe show that MRN sequentially localizes with the seDSB and sister chromatid at a collapsed replication fork. Ctp1, which has multivalent DNA-binding and DNA-bridging activities, has the same DNA interaction pattern. Provision of an intrachromosomal repair template alleviates the nonnucleolytic requirement for MRN to repair the broken fork. Mutations of zinc-coordinating cysteines in the Rad50 hook severely impair SCR. These data suggest that the MRN complex facilitates SCR by linking the seDSB and sister chromatid.
Mesh Terms:
Chromatids, Chromosomes, Fungal, DNA Repair, DNA Replication, DNA, Fungal, DNA-Binding Proteins, Exodeoxyribonucleases, Multiprotein Complexes, Mutation, Schizosaccharomyces, Schizosaccharomyces pombe Proteins
Chromatids, Chromosomes, Fungal, DNA Repair, DNA Replication, DNA, Fungal, DNA-Binding Proteins, Exodeoxyribonucleases, Multiprotein Complexes, Mutation, Schizosaccharomyces, Schizosaccharomyces pombe Proteins
Proc. Natl. Acad. Sci. U.S.A.
Date: Dec. 28, 2017
PubMed ID: 30104346
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