Rap1p telomere association is not required for mitotic stability of a C(3)TA(2) telomere in yeast

EMBO J. 2003 Apr 1;22(7):1688-96. doi: 10.1093/emboj/cdg154.


Telomeric DNA usually consists of a repetitive sequence: C(1-3)A/TG(1-3) in yeast, and C(3)TA(2)/T(2)AG(3) in vertebrates. In yeast, the sequence-specific DNA- binding protein Rap1p is thought to be essential for telomere function. In a tlc1h mutant, the templating region of the telomerase RNA gene is altered so that telomerase adds the vertebrate telomere sequence instead of the yeast sequence to the chromosome end. A tlc1h strain has short but stable telomeres and no growth defect. We show here that Rap1p and the Rap1p-associated Rif2p did not bind to a telomere that contains purely vertebrate repeats, while the TG(1-3) single-stranded DNA binding protein Cdc13p and the normally non-telomeric protein Tbf1p did bind this telomere. A chromosome with one entirely vertebrate-sequence telomere had a wild-type loss rate, and the telomere was maintained at a short but stable length. However, this telomere was unable to silence a telomere-adjacent URA3 gene, and the strain carrying this telomere had a severe defect in meiosis. We conclude that Rap1p localization to a C(3)TA(2) telomere is not required for its essential mitotic functions.

Publication types

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

MeSH terms

  • Base Sequence
  • Chromosome Deletion
  • Chromosomes, Fungal
  • DNA Primers
  • DNA-Binding Proteins / metabolism
  • Fluorescent Antibody Technique
  • Genes, Fungal
  • Mitosis*
  • Protein Binding
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / ultrastructure*
  • Saccharomyces cerevisiae Proteins / metabolism
  • Telomere*
  • Telomere-Binding Proteins / metabolism
  • Transcription Factors
  • rap1 GTP-Binding Proteins / metabolism*


  • Cdc13 protein, S cerevisiae
  • DNA Primers
  • DNA-Binding Proteins
  • Saccharomyces cerevisiae Proteins
  • TBF1 protein, S cerevisiae
  • Telomere-Binding Proteins
  • Transcription Factors
  • rap1 GTP-Binding Proteins