High level production and rapid purification of the E. coli trp repressor

Two small, multicopy, expression plasmids were constructed that permit convenient insertion of trpR, the structural gene for the trp repressor of Escherichia coli, with its natural ribosome binding site or adjacent to the ribosome binding site for the trp leader peptide. In these plasmids trpR is positioned between the strong regulated tac promoter and the rpoC transcription terminator. IPTG induction of lacIq strains bearing these plasmids results in the production of 25-50% of the soluble cell protein as trp repressor. Mutant and wild type repressors overproduced in this manner have been purified by simple procedures.