FIG. 1.

Deletion analysis and mapping of the ModE binding site at the E. coli napF promoter. Shown in panel A are the various DNA fragments, with relevant restriction sites, used in the construction of the napF-lacZ operon fusions detailed in the text. Restriction site locations relative to the start site of transcription are indicated in parentheses. Shown below is a schematic representation of the napF promoter region. The transcription start site is indicated (5), and coordinates relative to this start site are given in base pairs. The locations of Fnr, NarP (7), and ModE binding sites are indicated with brackets. (B) The DNA fragments used to map the ModE binding site are shown. The ability (+) or inability (−) of ModE to bind a particular fragment in a gel shift assay with 128 nM ModE is indicated.