Tel1 kinase and subtelomere-bound Tbf1 mediate preferential elongation of short telomeres by telomerase in yeast

EMBO Rep. 2007 Nov;8(11):1080-5. doi: 10.1038/sj.embor.7401082. Epub 2007 Oct 5.

Abstract

Telomerase enables telomere length homeostasis, exhibiting increasing preference for telomeres as their lengths decline. This regulation involves telomere repeat-bound Rap1, which provides a length-dependent negative feedback mechanism, and the Tel1 and Mec1 kinases, which are positive regulators of telomere length. By analysing telomere elongation of wild-type chromosome ends at single-molecule resolution, we show that in tel1Delta cells the overall frequency of elongation decreases considerably, explaining their short telomere phenotype. At an artificial telomere lacking a subtelomeric region, telomere elongation no longer increases with telomere shortening in tel1Delta cells. By contrast, a natural telomere, containing subtelomeric sequence, retains a preference for the elongation of short telomeres. Tethering of the subtelomere binding protein Tbf1 to the artificial telomere in tel1Delta cells restored preferential telomerase action at short telomeres; thus, Tbf1 might function in parallel to Tel1, which has a crucial role in a TG-repeat-controlled pathway for the activation of telomerase at short telomeres.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae* / genetics
  • Saccharomyces cerevisiae* / metabolism
  • Telomerase / genetics
  • Telomerase / metabolism*
  • Telomere / metabolism*
  • Transcription Factors

Substances

  • DNA-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • Saccharomyces cerevisiae Proteins
  • TBF1 protein, S cerevisiae
  • Transcription Factors
  • MEC1 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases
  • TEL1 protein, S cerevisiae
  • Telomerase