Analysis of mutagenic DNA repair in a thermoconditional repair mutant of Saccharomyces cerevisiae

Abstract

Using the thermoconditional yeast mutant rev2 ^ts that controls an apparently site-specific step of mutagenic DNA repair it was possible to measure the time course of REV2 dependent UV-induced reversion of the ochre allele his5-2 and recovery of survival for UV-treated stationary phase cells: due to the rev2 ^ts coded protein being active at 23° C, survival and mutation frequencies increased with duration of incubation under permissive conditions in growth medium before the temperature was shifted to 36° C (restrictive temperature). This increase was abolished in the presence of the protein synthesis inhibitor, cycloheximide. Furthermore, the REV2 dependent recovery of survival could be blocked or nearly blocked by cycloheximide added at any time during repair. Therefore, REV2 dependent repair can be characterized as a process requiring concomitant protein synthesis. These findings give further support to the concept that in yeast, mutagenesis involves UV inducible components of DNA repair.