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Elevated dNTP levels suppress hyper-recombination in Saccharomyces cerevisiae S-phase checkpoint mutants

Michael Fasullo1, Olga Tsaponina, Mingzeng Sun

  • 1Ordway Research Institute, 150 New Scotland Avenue, Albany, NY 12209, USA. mfasullo@ordwayresearch.org

Nucleic Acids Research
|December 8, 2009
PubMed

Insights

Checkpoint gene MEC1 loss in yeast increases DNA recombination due to low dNTPs. Restoring dNTP levels suppresses this hyper-recombination, suggesting a link between dNTPs and DNA repair pathways.

Area of Science:

  • * Molecular and Cellular Biology
  • * Genetics and Genomics
  • * DNA Replication and Repair

Background:

  • * MEC1 is an essential yeast gene, homologous to human ATR/ATM, crucial for S-phase checkpoint control.
  • * MEC1 loss-of-function mutants exhibit increased DNA recombination, suggesting replication stress generates recombinogenic lesions.
  • * Previous studies indicated higher rates of sister chromatid exchange (SCE), heteroallelic recombination, and translocations in mec1-21 mutants.

Purpose of the Study:

  • * To investigate the correlation between hyper-recombination in mec1-21 mutants and deoxyribonucleoside triphosphate (dNTP) levels.
  • * To determine the effect of modulating dNTP levels on recombination and mutagenesis in MEC1-deficient yeast.
  • * To elucidate the role of dNTP availability in suppressing recombinogenic lesions during replication stress.

Main Methods:

  • * Measurement of dNTP pools in various yeast mutants (mec1-21, dun1, sml1).
  • * Assessment of spontaneous sister chromatid exchange (SCE) rates.
  • * Analysis of spontaneous mutagenesis rates in relation to dNTP levels.

Main Results:

  • * Hyper-recombination in mec1-21 mutants correlates with significantly decreased dNTP levels.
  • * Deletion of SML1, which increases dNTP levels, reduced hyper-recombination phenotypes.
  • * Increased dNTP levels in mec1-21 dun1 sml1 mutants correlated with a higher rate of spontaneous mutagenesis.

Conclusions:

  • * Low dNTP levels contribute to the hyper-recombination observed in MEC1 checkpoint mutants.
  • * Modulating dNTP levels can suppress the formation of recombinogenic lesions.
  • * Findings suggest a critical role for dNTP availability in maintaining genome stability under replication stress.

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