Fig 1. Gel retardation assay of NrdR oligomeric and apo protein against the nrdAB promoter.

(A and B) As prepared NrdR, and (C and D) apo-form protein was titrated against nrdAB promoter DNA substrate. DNA binding activity of NrdR is shown without (left panel) and with (right panel) supplementation of ZnSO₄. The NrdR protein concentrations of 5, 10, 15 and 25 μM are shown in corresponding lanes. Filled triangles denote the positions of protein-DNA complex.