FIGURE 4.

Regulation of FabT expression by YycF. Upper panels, detection of the binding of YycF to the P_FabT promoter region. Autoradiograms of gel shift assays using the amplicon A and increasing concentrations of YycF in absence (A) or in presence of either poly (dI-dC) (B) or amplicon B (C). Arrows indicate the position of the retarded complex and free DNA. A schematic representation of the promoter region of fabTH-acpP operon including the -35 and -10 boxes of its putative promoter (P_FabT) as well as the putative binding site of YycF (underlined) is also depicted. Lower panels, effect of YycF on in vitro transcription. The run off transcripts obtained from P_FabT (D) and from P_X (E) synthesized by the E. coli RNA polymerase in the absence or in the presence of the indicated concentrations of YycF are depicted. The position and length of the transcripts generated are indicated. On the left of each panel is a G + A sequence ladder generated with an unrelated DNA fragment.