Relocalization of telomeric Ku and SIR proteins in response to DNA strand breaks in yeast

Cell. 1999 May 28;97(5):621-33. doi: 10.1016/s0092-8674(00)80773-4.


Telomeric TG-rich repeats and their associated proteins protect the termini of eukaryotic chromosomes from end-to-end fusions. Associated with the cap structure at yeast telomeres is a subtelomeric domain of heterochromatin, containing the silent information regulator (SIR) complex. The Ku70/80 heterodimer (yKu) is associated both with the chromosome end and with subtelomeric chromatin. Surprisingly, both yKu and the chromatin-associated Rap1 and SIR proteins are released from telomeres in a RAD9-dependent response to DNA damage. yKu is recruited rapidly to double-strand cuts, while low levels of SIR proteins are detected near cleavage sites at later time points. Consistently, yKu- or SIR-deficient strains are hypersensitive to DNA-damaging agents. The release of yKu from telomeric chromatin may allow efficient scanning of the genome for DNA strand breaks.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, Nuclear*
  • Bleomycin / pharmacology
  • Cell Cycle Proteins / metabolism
  • DNA Damage*
  • DNA Helicases*
  • DNA Repair*
  • DNA-Binding Proteins / metabolism*
  • Deoxyribonucleases, Type II Site-Specific / biosynthesis
  • Dimerization
  • Enzyme Induction
  • Fungal Proteins / metabolism*
  • GTP-Binding Proteins / metabolism
  • Genotype
  • Ku Autoantigen
  • Nuclear Proteins / metabolism*
  • Polymerase Chain Reaction
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*
  • Silent Information Regulator Proteins, Saccharomyces cerevisiae*
  • Telomere / genetics
  • Telomere / physiology
  • Transcription Factors / metabolism
  • rap GTP-Binding Proteins


  • Antigens, Nuclear
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Fungal Proteins
  • Nuclear Proteins
  • SIR4 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Silent Information Regulator Proteins, Saccharomyces cerevisiae
  • Transcription Factors
  • high affinity DNA-binding factor, S cerevisiae
  • Bleomycin
  • rad9 protein
  • SCEI protein, S cerevisiae
  • Deoxyribonucleases, Type II Site-Specific
  • GTP-Binding Proteins
  • DNA Helicases
  • XRCC5 protein, human
  • Xrcc6 protein, human
  • rap GTP-Binding Proteins
  • Ku Autoantigen