Rho-dependence of the terminator active at the end of the I region of transcription of bacteriophage f1.

Infection of rho- Escherichia coli cells with deletion mutant PII of bacteriophage f1 results in a miniphage RNA population composed of transcripts longer than those synthesized in the infection of rho+ cells. This indicates a Rho dependence of the terminator active at the end of the I region of transcription of bacteriophage f1. An estimate of the length of a transcript, which represents a good fraction of the RNA that passes beyond the terminator, indicates that the hairpin structure where synthesis of complementary strand DNA initiates also acts as a fairly efficient Rho-independent terminator.