Effects of chloramphenicol and rifampicin on the replication of R plasmid NR1 deoxyribonucleic acid in Escherichia coli.

The effects of inhibition of protein and ribonucleic acid (RNA) synthesis on the replication of the plasmids NR1 and F′lac in Escherichia coli were studied. When protein synthesis is inhibited, there is approximately a 25% increase in R plasmid deoxyribonucleic acid (DNA), but this newly synthesized DNA is not recoverable in the covalently closed circular (CCC) form until protein synthesis is allowed to resume. When RNA synthesis is inhibited, there is also approximately a 20% increase in R plasmid DNA, but this DNA is immediately recoverable in the CCC form. F′lac DNA, unlike R plasmid DNA, can continue to replicate for at least a generation time in the absence of protein synthesis, and this F′lac DNA is immediately recoverable in the CCC form.