THE FISSION YEAST UVDR DNA-REPAIR PATHWAY IS INDUCIBLE

In addition to nucleotide excision repair (NER), the fission yeast Sch izosaccharomyces pombe possesses a UV damage endonuclease (UVDE) for t he excision of cyclobutane pyrimidine dimers and 6-4 pyrimidine pyrimi dones. We have previously described UVDE as part of an alternative exc ision repair pathway, UVDR, for UV damage repair. The existence of two excision repair processes has long been postulated to exist in S.pomb e, as NER-deficient mutants are still proficient in the excision of UV photoproducts. UVDE recognizes the phosphodiester bond immediately 5' of the UV photoproducts as the initiating event in this process. We s how here that UVDE activity is inducible at both the level of uve1(+) mRNA and UVDE enzyme activity. Further, we show that UVDE activity is regulated by the product of the rad12 gene.