Differential interaction of nogalamycin with DNA of varying base composition.

Abstract

Nogalamycin inhibited the growth of KB cells in vitro 50% at a concentration of 0.005 [mu]g/ml over a 3-day period. At a level of 0.6 [mu]g/ml for 2 hr., nogalamycin caused 74% inhibition of RNA synthesis compared to 31% and 2% inhibition of DNA and protein synthesis, respectively. Nogalamycin is postulated to act by binding to the dA or dT moiety of DNA, thus inhibiting DNA-directed RNA synthesis. In vitro, DNA polymerase was much less sensitive to the antibiotic than was RNA polymerase. Therefore, nogalamycin acts on KB cells in a manner similar to actinomycin D, but with a different binding site. Nogalamycin inhibited the synthesis of certain DNA viruses in cell culture but was inactive against the RNA viruses tested.