Binding of CcpA to DNA fragments containing different cre sites. A) Nucleotide sequence of the citH-oadH intergenic regions. Locations of transcription start sites are indicated (+1); -10 and -35; regions are shown underlined. Arrows indicate direction of transcription and translation. CitO binding sequences are displayed in dotted boxes and putative cre sites in grey boxes. B, C and D) Images of gel shift assays performed with different amplicons (A, B and C respectively) covering each cre site or mutated cre site amplicons (Bm and Cm), increasing concentrations of CcpA and fixed concentrations of HPr or P-Ser-HPr.