Mode of action of phleomycin on Bacillus subtilis.

Phleomycin appears to act on the cell wall and membrane to induce the release of membrane-associated deoxyribonucleic acid (DNA) and the degradation of the DNA. Degradation occurs in a series of energy-requiring endonuclease and exonuclease reactions. These produce, first, single-strand breaks, then double-strand breaks, and finally almost complete solubilization of the cellular DNA. The in vivo inhibition of DNA synthesis by phleomycin is probably a secondary effect caused by the destruction of template DNA.