ISOLATION AND CHARACTERIZATION OF 3 MUTANTS WITH INCREASED SENSITIVITY TO PHOTOACTIVATED 3-CARBETHOXYPSORALEN IN SACCHAROMYCES-CEREVISIAE

The complementation and genetical analysis of yeast mutants sensitive to photoactivated 3-carbethoxypsoralen define three novel recessive mu tant alleles pso-5-1, pso6-1, and pso7-1. Their cross-sensitivity to U V254nm, radiomimetic mutagens, and to chemicals enhancing oxidative st ress suggest that these mutants are either impaired in metabolic steps protecting from oxidative stress or in mechanisms of the repair of ox ygen-dependent DNA lesions. None of the three novel mutant alleles blo ck the induction of reverse mutation by photoactivated mono- and bi-fu nctional psoralens, nitrogen mustards, or UV254nm.