Analysis of the regulatory elements of the Escherichia coli uvrC gene by construction of operon fusions.

The regulatory region of the Escherichia coli uvrC gene has been analysed by the subcloning of appropriate restriction fragments into the promoter probe vector pPV502. A series of plasmids carrying operon fusions to the gene for chloramphenicol acetyltransferase (cat) has been constructed. Three promoters capable of controlling uvrC have been identified (P1, P2 and P3), the majority of transcription being derived from the most distal of these promoters (P1). Transcription termination apparently plays some role in the control of the gene through premature termination of the P1-, but not the P2- or P3-derived transcripts. In addition, a promoter acting in the opposite direction to uvrC transcription has been detected. The activity of each of the promoters has been assayed under normal and SOS-inducing conditions. The uvrC gene is not apparently under the control of the recA-lexA regulatory circuit, unlike uvrA and uvrB. A series of recombinant plasmids carrying a 1.9 kb Bg/II fragment encoding most of the uvrC gene has been constructed. The properties of these plasmids suggest that the six amino acids at the carboxy-terminus of the uvrC gene product are not critical for DNA repair activity.