Positive regulation of meiotic DNA double-strand break formation by activation of the DNA damage checkpoint kinase Mec1(ATR)

Open Biol. 2013 Jul 31;3(7):130019. doi: 10.1098/rsob.130019.


During meiosis, formation and repair of programmed DNA double-strand breaks (DSBs) create genetic exchange between homologous chromosomes-a process that is critical for reductional meiotic chromosome segregation and the production of genetically diverse sexually reproducing populations. Meiotic DSB formation is a complex process, requiring numerous proteins, of which Spo11 is the evolutionarily conserved catalytic subunit. Precisely how Spo11 and its accessory proteins function or are regulated is unclear. Here, we use Saccharomyces cerevisiae to reveal that meiotic DSB formation is modulated by the Mec1(ATR) branch of the DNA damage signalling cascade, promoting DSB formation when Spo11-mediated catalysis is compromised. Activation of the positive feedback pathway correlates with the formation of single-stranded DNA (ssDNA) recombination intermediates and activation of the downstream kinase, Mek1. We show that the requirement for checkpoint activation can be rescued by prolonging meiotic prophase by deleting the NDT80 transcription factor, and that even transient prophase arrest caused by Ndt80 depletion is sufficient to restore meiotic spore viability in checkpoint mutants. Our observations are unexpected given recent reports that the complementary kinase pathway Tel1(ATM) acts to inhibit DSB formation. We propose that such antagonistic regulation of DSB formation by Mec1 and Tel1 creates a regulatory mechanism, where the absolute frequency of DSBs is maintained at a level optimal for genetic exchange and efficient chromosome segregation.

Keywords: Mec1 ATR; Spo11; Tel1 ATM; checkpoint; meiosis; recombination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Chromosome Segregation
  • DNA Breaks, Double-Stranded*
  • DNA Repair
  • DNA, Single-Stranded / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Endodeoxyribonucleases / genetics
  • Endodeoxyribonucleases / metabolism
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Meiosis*
  • Mutation
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Transcription Factors / metabolism


  • Cell Cycle Proteins
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • NDT80 protein, S cerevisiae
  • Nuclear Proteins
  • RAD17 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • MEC1 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases
  • TEL1 protein, S cerevisiae
  • CDC5 protein, S cerevisiae
  • Endodeoxyribonucleases
  • Spo11 protein, S cerevisiae