Lipiarmycin: An antibiotic inhibiting nucleic acid polymerases

Abstract

Lipiarmycin, a new antibiotic from a strain of Actinoplanes, was found to inhibit RNA polymerase from E. coli by blocking the initiation step of RNA synthesis like rifampicin. The drug was a much less potent and specific inhibitor than rifampicin: doses 10 to 20 times higher than those effective with the E. coli enzyme antagonized the mammalian RNA polymerases A and B as well as the DNA polymerases from prokaryotic and from eukaryotic cells. Both rifampicin and lipiarmycin acted as non-competitive inhibitors of either UTP or ATP substrates in the synthesis of the respective homopolymers promoted by the bacterial RNA polymerase with (dA)n · (dT)n templates.