Figure 4.
(a) Specific binding of TodT to todRX intergenic region. DNA fragments (253 bp and 196 bp) used in gel retardation assays (lanes B–D) are as marked. Lanes: A, DNA standard; B, no protein; C, 1 μg protein; D, 3 μg protein (see Materials and Methods). (b) DNase I footprint of TodT binding at the tod promoter. The complement of the sequence surrounding the protected region is written alongside; * and Δ indicate DNase I protected and hypersensitive sites, respectively; converging arrows indicate a 6-bp inverted repeat labeled as tod box in c, together with other sequence characteristics of the tod regulatory region. +1, transcription start site and −10 promoter element (Ptod) were as determined previously (4). SD, Shine–Dalgarno sequence; A+T rich sequence is overlined.