1D-06 Identification of LexA dependent promoters in E.coli O157:H7 genome

LexA is the repressor for the SOS regulon genes. Upon DNA damage, RecA inactivates the activity of LexA, and the SOS genes are induced. We made a screening system for cloning of the LexA dependent promoters from the E.coli O157:H7 genome. As a result, we identified 21 promoters, which regulate 16 known genes and 5 novel genes belonging to the SOS regulon. For example, we discovered that LexA regulates expression of the gene (ECs1575) encoding a DNA binding protein in the E.coli O157:H7 specific regions. We are analyzing their LexA binding sites by DNase ? footprinting experiment using purified LexA protein.