The Rad51 Pathway of Telomerase-Independent Maintenance of Telomeres Can Amplify TG1-3 Sequences in yku and cdc13 Mutants of Saccharomyces cerevisiae
AUTOR(ES)
Grandin, Nathalie
FONTE
American Society for Microbiology
RESUMO
In the yeast Saccharomyces cerevisiae, Cdc13, Yku, and telomerase define three parallel pathways for telomere end protection that prevent chromosome instability and death by senescence. We report here that cdc13-1 yku70Δ mutants generated telomere deprotection-resistant cells that, in contrast with telomerase-negative senescent cells, did not display classical crisis events. cdc13-1 yku70Δ cells survived telomere deprotection by exclusively amplifying TG1-3 repeats (type II recombination). In a background lacking telomerase (tlc1Δ), this process predominated over type I recombination (amplification of subtelomeric Y′ sequences). Strikingly, inactivation of the Rad50/Rad59 pathway (which is normally required for type II recombination) in cdc13-1 yku70Δ or yku70Δ tlc1Δ mutants, but also in cdc13-1 YKU70+ tlc1Δ mutants, still permitted type II recombination, but this process was now entirely dependent on the Rad51 pathway. In addition, delayed senescence was observed in cdc13-1 yku70Δ rad51Δ and cdc13-1 tlc1Δ rad51Δ cells. These results demonstrate that in wild-type cells, masking by Cdc13 and Yku prevents the Rad51 pathway from amplifying telomeric TG1-3 sequences. They also suggest that Rad51 is more efficient than Rad50 in amplifying the sequences left uncovered by the absence of Cdc13 or Yku70.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=155211Documentos Relacionados
- The Saccharomyces CDC13 protein is a single-strand TG1–3 telomeric DNA-binding protein in vitro that affects telomere behavior in vivo
- Dmc1 Functions in a Saccharomyces Cerevisiae Meiotic Pathway That Is Largely Independent of the Rad51 Pathway
- Aberrant Double-Strand Break Repair in rad51 Mutants of Saccharomyces cerevisiae
- Telomere-Associated Protein TIN2 Is Essential for Early Embryonic Development through a Telomerase-Independent Pathway
- Limited TTP supply affects telomere length regulation in a telomerase-independent fashion