UV irradiation causes the loss of viable mitotic recombinants in Schizosaccharomyces pombe cells lacking the G(2)/M DNA damage checkpoint

Genetics. 2002 Mar;160(3):891-908. doi: 10.1093/genetics/160.3.891.


Elevated mitotic recombination and cell cycle delays are two of the cellular responses to UV-induced DNA damage. Cell cycle delays in response to DNA damage are mediated via checkpoint proteins. Two distinct DNA damage checkpoints have been characterized in Schizosaccharomyces pombe: an intra-S-phase checkpoint slows replication and a G(2)/M checkpoint stops cells passing from G(2) into mitosis. In this study we have sought to determine whether UV damage-induced mitotic intrachromosomal recombination relies on damage-induced cell cycle delays. The spontaneous and UV-induced recombination phenotypes were determined for checkpoint mutants lacking the intra-S and/or the G(2)/M checkpoint. Spontaneous mitotic recombinants are thought to arise due to endogenous DNA damage and/or intrinsic stalling of replication forks. Cells lacking only the intra-S checkpoint exhibited no UV-induced increase in the frequency of recombinants above spontaneous levels. Mutants lacking the G(2)/M checkpoint exhibited a novel phenotype; following UV irradiation the recombinant frequency fell below the frequency of spontaneous recombinants. This implies that, as well as UV-induced recombinants, spontaneous recombinants are also lost in G(2)/M mutants after UV irradiation. Therefore, as well as lack of time for DNA repair, loss of spontaneous and damage-induced recombinants also contributes to cell death in UV-irradiated G(2)/M checkpoint mutants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle / radiation effects
  • Checkpoint Kinase 2
  • DNA Repair / radiation effects*
  • DNA Replication / radiation effects
  • Genes, cdc / radiation effects
  • Mutation / radiation effects
  • Protein Kinases / radiation effects
  • Protein Serine-Threonine Kinases*
  • Recombination, Genetic / radiation effects*
  • Schizosaccharomyces / genetics*
  • Schizosaccharomyces / radiation effects
  • Schizosaccharomyces pombe Proteins
  • Ultraviolet Rays


  • Schizosaccharomyces pombe Proteins
  • Protein Kinases
  • Checkpoint Kinase 2
  • Cds1 protein, S pombe
  • Protein Serine-Threonine Kinases