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Tel1 and Rif2 Regulate MRX Functions in End-Tethering and Repair of DNA Double-Strand Breaks

Corinne Cassani1, Elisa Gobbini1, Weibin Wang2

  • 1Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy.

Plos Biology
|February 23, 2016
PubMed

Insights

The Tel1 kinase promotes the MRX/MRN complex

Area of Science:

  • Molecular Biology
  • Genetics
  • Cellular Biology

Background:

  • DNA double-strand breaks (DSBs) trigger cellular repair mechanisms.
  • The MRX/MRN complex initiates DSB response by recruiting Tel1/ATM kinase.
  • The precise role of Tel1 in yeast DSB repair was previously unclear.

Purpose of the Study:

  • Investigate the function of Tel1 in DNA double-strand break repair in Saccharomyces cerevisiae.
  • Identify genetic interactions that reveal Tel1's role at DSBs.
  • Elucidate the mechanism by which Tel1 influences MRX/MRN complex activity.

Main Methods:

  • Synthetic phenotype screening to identify sensitizing alleles.
  • Analysis of MRX/MRN complex association with DNA ends.
  • Assessment of DNA repair pathways, including homologous recombination (HR) and nonhomologous end joining (NHEJ).

Main Results:

  • A novel rad50-V1269M allele was identified, which, in the absence of Tel1, causes sensitivity to genotoxic agents.
  • The MRV1269MX complex shows reduced DNA end association, further impaired by Tel1 absence.
  • tel1Δ rad50-V1269M cells exhibit defects in end-tethering and both HR and NHEJ repair.
  • Tel1 promotes MRX/MRN retention at DSBs, crucial for DNA binding, end-tethering, and repair.
  • Rif2 counteracts Tel1's role by enhancing MRX ATP hydrolysis and reducing end-tethering function.

Conclusions:

  • Tel1 kinase is essential for promoting MRX/MRN complex retention at DSBs.
  • This Tel1-mediated retention facilitates proper MRX/MRN-DNA binding, end-tethering, and subsequent repair.
  • Rif2 acts as a negative regulator of MRX/MRN function at DSBs, influencing its ATP-dependent activity and end-tethering capabilities.

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