Expression of cloned genes by in vivo insertion of tac promoter using a mini-Mu bacteriophage.

The strong trp-lac(tac) promoter has been incorporated into the mini-Mu bacteriophage genome to form a mini-Mu-tac (mMu-tac) expression transposon. This mMu-tac element can transpose efficiently in Escherichia coli cells when derepressed and occasionally insert into a recombinant plasmid. When mMu-tac integration occurs upstream of a cloned gene in the orientation of its transcription, the tac promoter can direct the expression of the gene insert. mMu-tac contains translation stop codons downstream of the tac promoter. Thus, mMu-tac should be useful to express only those genes containing their own translational information. We report here the successful expression in E. coli of several prokaryotic genes using the transposon expression system.