Fusion of the Escherichia coli lac genes to the ara promoter: a general technique using bacteriophage Mu-1 insertions.

The lac genes were fused to the ara promoter by means of phage phi 80 translocations of the lac and ara genes to att80. Homology for a crossover between the nonhomologous ara and lac operons was provided by mu insertions. Selection for recombinants within the mu insertions generated strains that had the ara promoter on one side of a mu insertion and the lac genes on the other side. ara-lac fusions were obtained from these strains by deleting the mu insertion. These fusions extend the techniques available for studies on the lac operon to studies on the ara operon. It should be possible to fuse other operons by this method.