A sensitive reporter gene system using bacterial luciferase based on a series of plasmid cloning vectors compatible with derivatives of pBR322.

We present a series of plasmid cloning vectors that are derived from a mutant of pSC101 possessing an elevated number of copies per genome equivalent. These vectors are compatible with any plasmid replicating from a pBR322 origin and use spectinomycin and/or streptomycin as a selective marker. They can be used whenever the simultaneous presence of several plasmids in the cell is desired. We use this vector system for the constitutive expression of the genes that are responsible for the production of the aldehyde substrate of bacterial luciferase. Transcription from promoters carried on a second plasmid can thus be measured within the living cell over a range of 3 orders of magnitude using bacterial luciferase as a reporter gene.