title: Coordinated nuclease activities counteract Ku at single-ended DNA double-strand breaks.
abstract: Repair of single-ended DNA double-strand breaks (seDSBs) by homologous recombination (HR) requires the generation of a 3' single-strand DNA overhang by exonuclease activities in a process called DNA resection. However, it is anticipated that the highly abundant DNA end-binding protein Ku sequesters seDSBs and shields them from exonuclease activities. Despite pioneering works in yeast, it is unclear how mammalian cells counteract Ku at seDSBs to allow HR to proceed. Here we show that in human cells, ATM-dependent phosphorylation of CtIP and the epistatic and coordinated actions of MRE11 and CtIP nuclease activities are required to limit the stable loading of Ku on seDSBs. We also provide evidence for a hitherto unsuspected additional mechanism that contributes to prevent Ku accumulation at seDSBs, acting downstream of MRE11 endonuclease activity and in parallel with MRE11 exonuclease activity. Finally, we show that Ku persistence at seDSBs compromises Rad51 focus assembly but not DNA resection.
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse, France.|Equipe labellisée Ligue Nationale Contre le Cancer.
authors.forename: Pauline
authors.initials: P
authors.lastname: Chanut
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse, France.|Equipe labellisée Ligue Nationale Contre le Cancer.|The Wellcome Trust and Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Britton
authors.affiliation: The Wellcome Trust and Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Coates
authors.affiliation: The Wellcome Trust and Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.|The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK.
authors.forename: Stephen P
authors.identifier: 0000-0001-9317-7937
authors.initials: SP
authors.lastname: Jackson
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse, France.|Equipe labellisée Ligue Nationale Contre le Cancer.
authors.forename: Patrick
authors.initials: P
authors.lastname: Calsou
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004706:Endodeoxyribonucleases; D006801:Humans; D000072200:Ku Autoantigen / Q000378:metabolism*; D000076228:MRE11 Homologue Protein / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D051135:Rad51 Recombinase / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; C121766:MRE11 protein, human; D009687:Nuclear Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D004706:Endodeoxyribonucleases; D000076228:MRE11 Homologue Protein; C410741:RBBP8 protein, human; C106893:XRCC5 protein, human; D000072200:Ku Autoantigen