TRANSCRIPT LEVELS OF THE SACCHAROMYCES-CEREVISIAE DNA-REPAIR GENE RAD18 INCREASE IN UV IRRADIATED-CELLS AND DURING MEIOSIS BUT NOT DURING THE MITOTIC CELL-CYCLE

We have examined the transcript levels of the Saccharomyces cerevisiae DNA repair gene RAD18 in UV irradiated cells, in the mitotic cell cycle, and during meiosis. Levels of RAD18 mRNA increased upon UV irradiation, but remained constant during the mitotic cell cycle. During meiosis, RAD18 mRNA levels rose about 4 fold at a stage coincident with the period when high levels of genetic recombination occur. RAD18 resembles the other DNA repair genes, RAD2, RAD6, RAD7, RAD23, and RAD54, all of which also exhibit increased transcription in response to DNA damage and during meiosis. Comparisons of sequences in 5' flanking regions of RAD genes suggest that different upstream sequences are involved in regulating the expression of DNA repair genes belonging to different epistasis groups.