Figure 6. DNA binding properties of MtrR-MBP.

Successive increases of MtrR-MBP incubated with 10 ng mtrCDE (A) or nadA (B) promoter regions to assess binding by gel-shift analysis. Arrow; primary complex of DNA and MtrR-MBP. (C) Competition assays. ³²P-labeled nadA promoter (384 bp) was incubated with 1.0 µg MtrR-MBP and competed with unlabeled nadA, mtrCDE (552 bp), and rnpB (354 bp) at 25, 50, and 100 times molar excess of labeled probe (lanes 3 through 14). The competing probe used is listed below each panel. Arrow; ³²P-labeled probe competed away from MtrR-MBP by unlabeled probe. Lane 1, labeled probe alone; lane 2, labeled probe and 0.5 µg MtrR-MBP without competitor.