Overproduction of the toxic protein, bovine pancreatic DNaseI, in Escherichia coli using a tightly controlled T7-promoter-based vector.

A synthetic gene coding for bovine pancreatic DNaseI has been cloned under the control of a T7 promoter present on the plasmid pET11. This construct yields a stable Escherichia coli transformant only when transcription from this promoter is tightly controlled. Production of recombinant DNaseI (reDNaseI) is achieved by infection of the cells with a mutant lambda phage, CE6, which carries the gene encoding T7 RNA polymerase. Induced bacterial cultures yield in excess of 2 mg per litre of reDNaseI after purification.