Frederick S. Hagen

Regulation of synthesis of bacteriophage T7 lysozyme mRNA

An analysis of the kinetics of synthesis of lysozyme and lysozyme mRNA after T7 infection reveals a lag between the appearance of lysozyme mRNA and the appearance of lysozyme activity. This lag is not due to post-translational modification of the protein or to the presence of a lysozyme inhibitor in early extracts. The lysozyme mRNA does not appear to be unusually stable as judged by the decline in functional mRNA concentration late in infection. The lysozyme mRNA is transcribed in vivo only by the phage-coded RNA polymerase, whereas in vitro the E. coli RNA polymerase can transcribe the lysozyme gene. However, transcription of the lysozyme gene in vitro by E. coli RNA polymerase is prevented by the host termination factor, rho. Thus, the lysozyme gene is clearly one of the late genes of T7 rather than an early gene, and its messenger appears to be under some form of transient translational control.