A VERSATILE VECTOR FOR CONTROLLED EXPRESSION OF GENES IN ESCHERICHIA-COLI AND SALMONELLA-TYPHIMURIUM

We have constructed two expression vectors based on the pJF118HE vecto r developed for Escherichia coli by Furste et al. [Gene 48 (1986) 119- 131]. The tac promoter (ptac) was exchanged for the trc promoter (ptrc ) and an NdeI site was created at the appropriate distance from the ri bosome-binding site. The NdeI site permits cloning of a gene at its tr anslation start point without altering the amino-acid sequence of the synthesized protein, while ptrc and the lacI(Q) gene confer inducible and controlable expression. We have tested these plasmids in E. coli a nd Salmonella typhimurium.