title: MEC1-dependent redistribution of the Sir3 silencing protein from telomeres to DNA double-strand breaks.
abstract: The yeast Sir2/3/4p complex is found in abundance at telomeres, where it participates in the formation of silent heterochromatin and telomere maintenance. Here, we show that Sir3p is released from telomeres in response to DNA double-strand breaks (DSBs), binds to DSBs, and mediates their repair, independent of cell mating type. Sir3p relocalization is S phase specific and, importantly, requires the DNA damage checkpoint genes MEC1 and RAD9. MEC1 is a homolog of ATM, mutations in which cause ataxia telangiectasia (A-T), a disease characterized by various neurologic and immunologic abnormalities, a predisposition for cancer, and a cellular defect in repair of DSBs. This novel mode by which preformed DNA repair machinery is mobilized by DNA damage sensors may have implications for human diseases resulting from defective DSB repair.
authors.affiliation: Massachusetts Institute of Technology, Department of Biology, Cambridge 02139, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Mills
authors.forename: D A
authors.initials: DA
authors.lastname: Sinclair
authors.forename: L
authors.initials: L
authors.lastname: Guarente
mesh_terms: D001260:Ataxia Telangiectasia / Q000235:genetics; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D002843:Chromatin / Q000235:genetics / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D005720:Gamma Rays; D006570:Heterochromatin / Q000235:genetics / Q000528:radiation effects; D006655:Histone Deacetylases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D010957:Plasmids; D017346:Protein Serine-Threonine Kinases; D011506:Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics* / Q000528:radiation effects; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D056564:Sirtuin 1; D056565:Sirtuin 2; D037761:Sirtuins; D016615:Telomere / Q000235:genetics* / Q000528:radiation effects; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins; D014466:Ultraviolet Rays
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006570:Heterochromatin; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; C084122:SIR3 protein, S cerevisiae; C061573:SIR4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; C069930:rad9 protein; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C087778:SIR2 protein, S cerevisiae; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D056565:Sirtuin 2; D037761:Sirtuins; D006655:Histone Deacetylases