Tel1 and Rad51 are involved in the maintenance of telomeres with capping deficiency

Nucleic Acids Res. 2013 Jul;41(13):6490-500. doi: 10.1093/nar/gkt365. Epub 2013 May 15.

Abstract

Vertebrate-like T2AG3 telomeres in tlc1-h yeast consist of short double-stranded regions and long single-stranded overhang (G-tails) and, although based on Tbf1-capping activity, they are capping deficient. Consistent with this idea, we observe Y' amplification because of homologous recombination, even in the presence of an active telomerase. In these cells, Y' amplification occurs by different pathways: in Tel1(+) tlc1h cells, it is Rad51-dependent, whereas in the absence of Tel1, it depends on Rad50. Generation of telomeric G-tail, which is cell cycle regulated, depends on the MRX (Mre11-Rad50-Xrs2) complex in tlc1h cells or is MRX-independent in tlc1h tel1Δ mutants. Unexpectedly, we observe telomere elongation in tlc1h lacking Rad51 that seems to act as a telomerase competitor for binding to telomeric G-tails. Overall, our results show that Tel1 and Rad51 have multiple roles in the maintenance of vertebrate-like telomeres in yeast, supporting the idea that they may participate to evolutionary conserved telomere protection mechanism/s acting at uncapped telomeres.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA-Binding Proteins / genetics
  • Gene Deletion
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / physiology*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / physiology*
  • Rad51 Recombinase / metabolism
  • Rad51 Recombinase / physiology*
  • Recombination, Genetic
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Saccharomyces cerevisiae Proteins / physiology*
  • Telomerase / antagonists & inhibitors
  • Telomere / metabolism*
  • Telomere Homeostasis*

Substances

  • DNA-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • RAD50 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Protein Serine-Threonine Kinases
  • TEL1 protein, S cerevisiae
  • RAD51 protein, S cerevisiae
  • Rad51 Recombinase
  • Telomerase