Effect of DNA Repair systems on antibacterial and mutagenic activity of an antitumor protein, neocarzinostatin.

Antibacterial and mutagenic effects of an antitumor protein, neocarzinostatin (NCS), on isogenic strains of Escherichia coli with normal or defective DNA repair systems were studied. Growth of the strains lacking recA gene was inhibited by NCS with much lower concentration than in the case of those possessing it, while the "differential inhibition for growth" (DIG) between the strains uvrA+ and uvrA- was not seen. NCS induces mutation in recA+ strains but not significantly in recA-, while no such difference of mutagenesis was noticed between the strains uvrA+ and uvrA-. These results suggest that NCS produces hardly excisable DNA damage which is repaired by an error-prone recombination process.