The fission yeast Taz1 protein protects chromosomes from Ku-dependent end-to-end fusions

Mol Cell. 2001 Jan;7(1):55-63. doi: 10.1016/s1097-2765(01)00154-x.


A paramount role of telomeres is to prevent chromosome fusions. The fission yeast Taz1 protein regulates diverse telomere functions but is not essential for growth under stress-free conditions. Strikingly, however, taz1(-) cells exhibit lethal telomere fusions when subjected to nitrogen starvation, a treatment that induces an uncommitted G1 state. These fusions are formed by Ku-dependent nonhomologous end joining. Fusions also occur during normal growth in taz1(-) cells that lack rad22(+), a gene involved in homologous recombination. Our data suggest a model whereby taz1(-) telomeres are exposed to the prevailing mode of DNA repair, which is dictated by the cell cycle. Thus, Taz1 caps chromosome ends and provides the telomerespecific interaction that prevents Ku from treating telomeres as double-strand breaks.

Publication types

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

MeSH terms

  • Antigens, Nuclear*
  • Bacterial Outer Membrane Proteins / genetics*
  • Bacterial Outer Membrane Proteins / metabolism
  • Chromosomes, Fungal / genetics*
  • Chromosomes, Fungal / metabolism
  • DNA Helicases*
  • DNA Repair / physiology*
  • DNA, Fungal / genetics
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Escherichia coli Proteins*
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • G1 Phase / genetics
  • Ku Autoantigen
  • Nitrogen
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Phosphoprotein Phosphatases*
  • Protein Kinases*
  • Saccharomyces cerevisiae Proteins*
  • Schizosaccharomyces / cytology
  • Schizosaccharomyces / genetics*
  • Schizosaccharomyces / metabolism
  • Schizosaccharomyces pombe Proteins*
  • Starvation
  • Telomere / genetics
  • Telomere / metabolism
  • Telomere-Binding Proteins


  • Antigens, Nuclear
  • Bacterial Outer Membrane Proteins
  • DNA, Fungal
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Fungal Proteins
  • Nuclear Proteins
  • Saccharomyces cerevisiae Proteins
  • Schizosaccharomyces pombe Proteins
  • Taz1 protein, E coli
  • Telomere-Binding Proteins
  • high affinity DNA-binding factor, S cerevisiae
  • rad52 protein, S pombe
  • taz1 protein, S pombe
  • Protein Kinases
  • Phosphoprotein Phosphatases
  • DNA Helicases
  • XRCC5 protein, human
  • Xrcc6 protein, human
  • Ku Autoantigen
  • Nitrogen