title: The extent of error-prone replication restart by homologous recombination is controlled by Exo1 and checkpoint proteins.
abstract: Genetic instability, a hallmark of cancer, can occur when the replication machinery encounters a barrier. The intra-S-phase checkpoint maintains stalled replication forks in a replication-competent configuration by phosphorylating replisome components and DNA repair proteins to prevent forks from catastrophically collapsing. Here, we report a novel function of the core Schizosaccharomyces pombe checkpoint sensor kinase, Rad3 (an ATR orthologue), that is independent of Chk1 and Cds1 (a CHK2 orthologue); Rad3(ATR) regulates the association of recombination factors with collapsed forks, thus limiting their genetic instability. We further reveal antagonistic roles for Rad3(ATR) and the 9-1-1 clamp - Rad3(ATR) restrains MRN- and Exo1-dependent resection, whereas the 9-1-1 complex promotes Exo1 activity. Interestingly, the MRN complex, but not its nuclease activity, promotes resection and the subsequent association of recombination factors at collapsed forks. The biological significance of this regulation is revealed by the observation that Rad3(ATR) prevents Exo1-dependent genome instability upstream of a collapsed fork without affecting the efficiency of recombination-mediated replication restart. We propose that the interplay between Rad3(ATR) and the 9-1-1 clamp functions to fine-tune the balance between the need for the recovery of replication through recombination and the risk of increased genome instability.
authors.affiliation: Genome Damage and Stability Centre, University of Sussex, Brighton, Sussex BN1 9RQ, UK.
authors.forename: Ellen
authors.initials: E
authors.lastname: Tsang
authors.affiliation: Genome Damage and Stability Centre, University of Sussex, Brighton, Sussex BN1 9RQ, UK.
authors.forename: Izumi
authors.initials: I
authors.lastname: Miyabe
authors.affiliation: Institut Curie-Centre National de la Recherche Scientifique, UMR3348, Réponse Cellulaire aux Perturbations de la Réplication, Centre Universitaire, Bat 110, 91405 Orsay, France.
authors.forename: Ismail
authors.initials: I
authors.lastname: Iraqui
authors.affiliation: Department of Biotechnology, College of Agriculture, No.58 Renmin Avenue, Haikou, Hainan Province 570228, P.R. China.
authors.forename: Jiping
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Institut Curie-Centre National de la Recherche Scientifique, UMR3348, Réponse Cellulaire aux Perturbations de la Réplication, Centre Universitaire, Bat 110, 91405 Orsay, France Sarah.Lambert@curie.fr a.m.carr@sussex.ac.uk.
authors.forename: Sarah A E
authors.initials: SA
authors.lastname: Lambert
authors.affiliation: Genome Damage and Stability Centre, University of Sussex, Brighton, Sussex BN1 9RQ, UK Sarah.Lambert@curie.fr a.m.carr@sussex.ac.uk.
authors.forename: Antony M
authors.initials: AM
authors.lastname: Carr
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism*; D000071877:Checkpoint Kinase 1; D004261:DNA Replication / Q000502:physiology*; D005090:Exodeoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D042822:Genomic Instability; D059765:Homologous Recombination; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D029702:Schizosaccharomyces pombe Proteins; D011494:Protein Kinases; D000071877:Checkpoint Kinase 1; C000605873:Chk1 protein, S pombe; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I
keywords: Checkpoint; Genome instability; Homologous recombination