Abstract
Escherichia coli phage N4 transcription is resistant to rifampicin, an inhibitor of the host RNA polymerase, even when the drug is added prior to infection. A rifampicin-resistant RNA polymerase has been detected in disrupted N4 virions. This enzyme shows a requirement for the four ribonucleoside 5'-triphosphates and exogenous denatured DNA. With denatured N4 DNA, the preferred template, transcription is asymmetric. The virion RNA polymerase apparently is necessary for phage development because a conditional lethal N4 mutant shows temperature-sensitive RNA synthesis in vivo as well as a temperature-sensitive RNA polymerase in disrupted virions.