Activation of bacteriophage Mu mom transcription by C protein does not require specific interaction with the carboxyl-terminal region of the alpha or sigma 70 subunit of Escherichia coli RNA polymerase.

Late in its growth cycle, transcription of the phage Mu mom Promoter (Pmom) is activated by the phage gene product, C, a site-specific DNA binding protein. In vitro transcription analyses showed that this activation does not require specific contacts between C and the carboxyl-terminal region of the alpha or sigma 70 subunit of Escherichia coli RNA polymerase. Unexpectedly, these results are in contrast to those known for another Mu-encoded transcriptional activator, Mor, which has a high degree of sequence identity with C and appears to interact with the carboxyl termini of both alpha and sigma 70.