Repair of UV damage in the fission yeast Schizosaccharomyces pombe

This review is concerned with repair and tolerance of UV damage in the fiss ion yeast, Schizosaccharomyces pombe and with the differences between Sch. pombe and budding yeast, Saccharomyces cerevisiae in their response to UV i rradiation. Sch. pombe is not as sensitive to ultra-violet radiation as Sac . cerevisiae nor are any of its mutants as sensitive as the most sensitive Sac. cerevisiae mutants. This can be explained in part by the fact that Sch . pombe, unlike budding yeast or mammalian cells, has an extra pathway (UVE R) for excision of UV photoproducts in addition to nucleotide excision repa ir (NER). However, even in mutants lacking this additional pathway, there a re significant differences between the two yeasts. Sch. pombe mutants that lack the alternative pathway are still more W-resistant than wild-type Sac. cerevisiae; recombination mutants are significantly UV sensitive (unlike t heir Sac. cerevisiae equivalents); mutants lacking the second pathway are s ensitized to UV by caffeine; and checkpoint mutants are relatively more sen sitive than the budding yeast equivalents. In addition, Sch. pombe has no p hotolyase. Thus, the response to UV in the two yeasts has a number of signi ficant differences, which are not accounted for entirely by the existence o f two alternative excision repair pathways. The long G2 in Sch.. pombe, its well-developed recombination pathways and efficient cell cycle checkpoints are all significant components in survival of UV damage. (C) 2000 Elsevier Science B.V. All rights reserved.