title: The non-homologous end-joining protein Nej1p is a target of the DNA damage checkpoint.
abstract: DNA double-strand breaks (DSBs), which are generated by ionizing radiation (IR) and a range of other DNA damaging agents, are repaired by homologous recombination (HR) or non-homologous end-joining (NHEJ). Previous studies have shown that NHEJ in Saccharomyces cerevisiae requires the Yku70p-Yku80p heterodimer and a complex consisting of DNA Ligase IV, Lif1p and Nej1p. Here, we report that Nej1p is phosphorylated in response to DNA damage in a manner that relies on the DNA damage checkpoint kinases Mec1p, Rad53p and Dun1p. By using a mutational approach, we have identified a consensus Dun1p phosphorylation site in Nej1p, and mutation of conserved serine residues within it leads to decreased NHEJ efficiency. These data, together with previous findings that Rad55p--a protein involved in HR--is phosphorylated analogously, point to there being a broad signalling network connecting DNA damage checkpoint responses with the regulation of DNA DSB repair activities.
authors.affiliation: Wellcome Trust and Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Ahnesorg
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Jackson
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites / Q000235:genetics; D018797:Cell Cycle Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D064447:Checkpoint Kinase 2; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005816:Genetic Complementation Test; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C114091:LIF1 protein, S cerevisiae; C441270:NEJ1 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D012694:Serine; D011494:Protein Kinases; C104169:DUN1 protein, S cerevisiae; D064447:Checkpoint Kinase 2; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae