Regulation of theEscherichia coliexcision repair geneuvrC.Overlap between theuvrCstructural gene and the region coding for a 24 kD protein

Open Access
Publisher Website
Google Scholar
Abstract
The UvrA, UvrB and UvrC proteins of E.coli are subunits of a DNA repair enzyme, the ABC exinuclease. In this paper we study the uvrC regulatory region. The uvrC structural gene is preceeded by an open reading frame encoding a 24 KD prote1n (1). A uvrC promoter has been mapped within this gene. The transcription start of a second promoter located 5' of the 24 kD gene is mapped in vivo. We show that transcription from both promoters on the chromosome is not inducible by UV damage.The possible translation start codons of the UvrC and of the 24 kD protein are determined. Sequences encoding the N-terminal part of the UvrC protein overlap with sequences encoding the C-terminal part of the 24 kD protein. To examine a possible function of the 24 kD gene in repair, a 24 kD insertion mutant was created in the chromosome. The mutant however only slightly affects the UV sensitivity of the cell. Transcription of P3 alone provides sufficient UvrC protein for the normal repair of UV lesions.