Multiple control elments for theuvrCgene unit ofEscherichia coli

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Abstract
We have sequenced the control region of the uvrC protein including two open reading frames (ORF) encoding polypeptides of 28 kd and 23 kd molecular weight. The uvrC gene is preceded by five promoters. The P1, P2a and P2b promoter sequences are 5' to the 28 kd and the 23 kd proteins respectively. The P3 and P4 promoters are located within the structural gene for the 23 kd protein. The P3 promoter is required for adequate in vivo expression. There are three putative lexA protein binding sites, detected at the 3' end of the 28 kd protein (lexA1), within the coding sequences for the 23 kd protein (lexA2) and within the P3 promoter (lexA3). Promoter P2 is responsible for transcription of the uvrC gene, producing transcripts of 2.8 and 1.6 kb. The upstream region including the 28 kd protein is required for enhanced expression under non-induced conditions. These results show that the uvrC gene is controlled by multiple promoters and is transcribed as part of a multigene unit.