The molecular mechanism of virus induction. I. A procedure for the biochemical assay of prophage induction.

The basic conditions for use of a new biochemical assay of bacteriophage induction are described. This method is based on the read-through transcription of the tryptophan operon integrated into an "early" transcribed region of the bacteriophage phi80 or gamma genome. Inactivation of repressor molecules was assayed by measuring, in the presence of tryptophan, anthranilate synthetase activity in an Escherichia coli (trpE-) phi80 or gamma lysogen infected with phi80ptrp or gammaptrp, respectively, and treated with mitomycin C or UV irradiation. This method provides a sensitive and easy means to analyze the induction process.