We have carried out experiments to identify the regulatory regions of the uvrC gene of Escherichia coli. A uvrC+ plasmid, pUV7, containing the intact transcriptional unit for the uvrC gene, was used to subclone either the structural gene or combinations of the structural gene and 5′-flanking sequences. The plasmids so constructed were tested for ability to restore UV-resistant phenotype to uvrC-; cells as an indication of expression of the uvrC gene. The chromosomal DNA in plasmid pUV7 was probed for strong binding with E. coli RNA polymerase in an attempt to identify a restriction fragment which bears the regulatory sequences for the uvrC transcriptional unit. The results indicate that DNA sequences at least 0.9 Kb upstream from the structural gene, but not the 5′-proximal sequences, regulate expression of the uvrC gene. Analysis of protein synthesis encoded by plasmid pUV7 and its derivatives suggest that there may be another gene that lies between the promoter and the uvrC gene and codes for a 27,000-Mr protein. The relation of this gene to uvrC function is not clear.
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