title: Smc5/6 is required for repair at collapsed replication forks.
abstract: In eukaryotes, three pairs of structural-maintenance-of-chromosome (SMC) proteins are found in conserved multisubunit protein complexes required for chromosomal organization. Cohesin, the Smc1/3 complex, mediates sister chromatid cohesion while two condensin complexes containing Smc2/4 facilitate chromosome condensation. Smc5/6 scaffolds an essential complex required for homologous recombination repair. We have examined the response of smc6 mutants to the inhibition of DNA replication. We define homologous recombination-dependent and -independent functions for Smc6 during replication inhibition and provide evidence for a Rad60-independent function within S phase, in addition to a Rad60-dependent function following S phase. Both genetic and physical data show that when forks collapse (i.e., are not stabilized by the Cds1Chk2 checkpoint), Smc6 is required for the effective repair of resulting lesions but not for the recruitment of recombination proteins. We further demonstrate that when the Rad60-dependent, post-S-phase Smc6 function is compromised, the resulting recombination-dependent DNA intermediates that accumulate following release from replication arrest are not recognized by the G2/M checkpoint.
authors.affiliation: Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, United Kingdom.
authors.forename: Eleni
authors.initials: E
authors.lastname: Ampatzidou
authors.forename: Anja
authors.initials: A
authors.lastname: Irmisch
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: O'Connell
authors.forename: Johanne M
authors.initials: JM
authors.lastname: Murray
mesh_terms: D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000502:physiology*; D004249:DNA Damage / Q000235:genetics; D004260:DNA Repair / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D004271:DNA, Fungal / Q000096:biosynthesis*; D006918:Hydroxyurea / Q000494:pharmacology; D009154:Mutation; D011995:Recombination, Genetic; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D029702:Schizosaccharomyces pombe Proteins; C486628:Smc5 protein, S pombe; C486630:smc6 protein, S pombe; D006918:Hydroxyurea