Replication of RNA bacteriophage R23. II. Inhibition of phage-specific RNA synthesis by phleomycin

The multiplication in Escherichia coli of both DNA and RNA bacteriophages was found to be inhibited by the antibiotic phleomycin. The cessation of RNA phage replication appeared to result from inhibition of phage-directed RNA synthesis. After addition of phleomycin, there was simultaneous cessation of synthesis of both single-stranded phage RNA and RNase-resistant RNA. Synthesis of coat protein, phage assembly and the formation of infective particles were unaffected and phleomycin treatment did not result in defective particles. This drug also inhibited the synthesis of bacterial RNA, and secondarily, of bacterial protein in E. coli. Inhibition by phleomycin of viral RNA polymerase and DNA-dependent RNA polymerase activities was evident in in vitro studies and there was evidence of phleomycin binding to RNA.