Cloning of the A gene of bacteriophage Mu and purification of its product, the Mu transposase.

The bacteriophage Mu transposase (the Mu A gene product), which is absolutely required for both integration of Mu and replicative transposition during the lytic cycle, has been overproduced by cloning the gene on a plasmid under the control of the phage lambda PL promoter. The protein has been purified to near homogeneity from the lysate of heat-induced cells of a strain carrying the plasmid. The purified protein is active as judged by its ability to complement Mu A- cell extracts for supporting Mu transposition in a cell-free reaction.