T4 Bacteriophage-coded RNA polymerase subunit blocks host transcription and unfolds the host chromosome.
T4 bacteriophage mutants selected for their ability to grow with cytosine in their DNA are defective in host transcriptional shutoff and host chromosome unfolding. The host RNA polymerase purifed from cells infected by such a mutant lacks a small T4-coded subunit.
Chromosome Mapping↗