Characterisation of the Escherichia coli mfd promoter.

The bacterial mfd gene encodes a transcription-repair coupling factor that mediates the preferential repair of DNA damage in the template strand of active transcriptional units. In this report, the transcription start site for the Escherichia coli mfd gene was determined in vivo and in vitro, and the DNA determinants for mfd transcription by deletion and site-directed mutagenesis were defined. A canonical sigma(70)-dependent promoter, mfd P1, was responsible for the majority of mfd transcription, and a core region consisting of residues -42 to +5 was sufficient for full activity in rich and minimal media.