Expression vectors based on the rac fusion promoter.

The -35 region of the rrnB P2 promoter and the -10 region of the lacZpo promoter-operator were fused to form the strong and regulatable rac promoter. Vectors were constructed that allow the attachment of protein-coding sequences to the beta-galactosidase alpha-peptide (LacZ alpha) in any reading frame. By introducing a high-copy-number mutation, the synthesis of a LacZ alpha-chloramphenicol acetyltransferase fusion protein reached more than 60% of total cell protein in Escherichia coli.