Organisation and control of the Escherichia coli uvrC gene

The Escherichia coli uvrC gene has been cloned into multicopy plasmids from the transducing phage lambda uvrC+ and the structural gene assigned to a 1.9-kb BglII fragment. Deletion of upstream sequences shows the presence of an in vivo uvrC promoter close to the start of the structural gene, as confirmed by subcloning the uvrC fragment into actively transcribed or 'promoter-free' restriction sites in various plasmid vectors. The control of uvrC transcription has been investigated using hybrid uvrC-cat operons. There are at least two promoters upstream of uvrC. Only the proximal promoter, some two orders of magnitude less effective than the cat promoter, is required for in vivo expression of the uvrC gene. We can find no evidence that expression of the uvrC gene on multicopy plasmids is either autogenously controlled or controlled by the product of the lexA gene.