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

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