Influence of different inhibitors on the activity of the RAD54 dependent step of DNA repair in Saccharomyces cerevisiae.

The recombinagenic pathway of DNA repair in yeast was characterized by the effect of different inhibitors on the temperature-dependent survival after gamma-irradiation in haploid cells of the thermoconditional mutant rad54-3. Blocking protein synthesis with cycloheximide in replicating cells caused partial inhibition of the RAD54 dependent function but some repair activity remained detectable. This indicates that gamma-rays can induce RAD54 activity above some constitutive level of function. Inhibition of DNA replication by hydroxyurea efficiently blocked the RAD54 dependent function in stationary-phase cells but not in logarithmic-phase cells. In logarithmic-phase cells, we found a strong inhibitory effect of caffeine on the RAD54 mediated repair process.