Compromised DNA repair enhances sensitivity of the yeast RNR3-lacZ genotoxicity testing system

The RNR3-lacZ genotoxicity testing system was developed based on the induction of a Saccharomyces cerevisiae RNR3-lacZ reporter gene in response to a broad range of DNA-damaging agents. In order to enhance the sensitivity of the RNR3-lacZ system, several deletion mutant strains representing different re-pair pathways were created and examined for their effects on RNR3-lacZ expression. It was found that inactivation of different DNA repair pathways has profound effects on the DNA damage induction of RNR3 expression. Although deletion of MAG1 in the base excision repair pathway enhances the detection sensitivity to DNA-alkylating agents, and deletion of RAD2 in the nucleotide excision repair pathway enhances the detection sensitivity to ul-traviolet and agents that produce bulky lesions, inactivation of genes involved in the recombination repair and postreplication repair variably reduces RNR3-lacZ induction. This study not onl