Influence of caffeine on the induction of SOS functions recA and umuC by mitomycin C in Escherichia coli.

Caffeine alone induced the SOS functions recA and umuC in wild type recA-lacZ and umuC-lacZ fusion systems in Escherichia coli strains. Caffeine was also able to induce umuC in a umuC-lacZ fusion strain defective in excision repair. Caffeine however was unable to significantly induce recA in a recA-lacZ fusion strain defective in excision repair. Mitomycin C (MMC) at a concentration of 0.5 microgram/ml functioned as a stronger inducer of recA and umuC than caffeine at 2 mg/ml. Cell growth in the presence of both caffeine (2 mg/ml) and MMC (0.05, 0.1 and 0.5 microgram/ml) resulted in primarily an additive induction of recA and umuC.