Telomerase-null survivor screening identifies novel telomere recombination regulators

PLoS Genet. 2013;9(1):e1003208. doi: 10.1371/journal.pgen.1003208. Epub 2013 Jan 17.

Abstract

Telomeres are protein-DNA structures found at the ends of linear chromosomes and are crucial for genome integrity. Telomeric DNA length is primarily maintained by the enzyme telomerase. Cells lacking telomerase will undergo senescence when telomeres become critically short. In Saccharomyces cerevisiae, a very small percentage of cells lacking telomerase can remain viable by lengthening telomeres via two distinct homologous recombination pathways. These "survivor" cells are classified as either Type I or Type II, with each class of survivor possessing distinct telomeric DNA structures and genetic requirements. To elucidate the regulatory pathways contributing to survivor generation, we knocked out the telomerase RNA gene TLC1 in 280 telomere-length-maintenance (TLM) gene mutants and examined telomere structures in post-senescent survivors. We uncovered new functional roles for 10 genes that affect the emerging ratio of Type I versus Type II survivors and 22 genes that are required for Type II survivor generation. We further verified that Pif1 helicase was required for Type I recombination and that the INO80 chromatin remodeling complex greatly affected the emerging frequency of Type I survivors. Finally, we found the Rad6-mediated ubiquitination pathway and the KEOPS complex were required for Type II recombination. Our data provide an independent line of evidence supporting the idea that these genes play important roles in telomere dynamics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosomes / genetics
  • DNA Helicases* / genetics
  • DNA Helicases* / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Genomic Instability
  • Homologous Recombination*
  • RNA / genetics
  • RNA / metabolism
  • Saccharomyces cerevisiae Proteins* / genetics
  • Saccharomyces cerevisiae Proteins* / metabolism
  • Saccharomyces cerevisiae* / genetics
  • Saccharomyces cerevisiae* / metabolism
  • Signal Transduction
  • Telomerase / genetics*
  • Telomerase / metabolism
  • Telomere / genetics
  • Telomere Homeostasis / genetics
  • Ubiquitination

Substances

  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • telomerase RNA
  • RNA
  • Telomerase
  • PIF1 protein, S cerevisiae
  • DNA Helicases

Grant support

This work was supported by grants from National Natural Science Foundation of China (31230040) and Ministry of Science and Technology of China (2013CB910403 and 2011CB966301) to J-QZ, and China Postdoctoral Science Foundation (20100470742) and Postdoctoral Foundation of Shanghai (08R2141058) to WD. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.