Lysis of Escherichia coli by induction of cloned phi X174 genes.

The largest of the fragments produced by AluI digestion of phi X174 RFI DNA comprises genes E and J as well as parts of genes D and F. This DNA fragment (1007 bp) was cloned into the lac z' gene of plasmid pUR222. In the recombinant plasmid pUH12, transcription of the phi X174 genes is controlled by the lac p-o region. Induction of the cloned genes by addition of the lac inducer, IPTG, resulted in lysis of the bacteria. Cloning of the corresponding AluI-fragment from phi X174am3 DNA, carrying an amber mutation in gene E, showed that the expression of this gene alone is sufficient to trigger cell lysis. The time interval between the addition of IPTG and the onset of lysis depended on the concentration of the inducer, however, the rate of lysis was similar at all IPTG concentrations used.