DNA binding ability of Zur. The upstream region of znuA (panel a) or rovA (f), with or without a predicted Zur binding site, respectively, was amplified by PCR and used as target DNA probe in EMSA. For EMSA, the [γ-32P]-labeled target DNA probes (1000 to 2000 c.p.m/μl) were incubated with the Zur protein in the presence or absence of 100 μM ZnCl2. Increasing amounts of Zur (b and g), ZnCl2(c), or EDTA (d and e) were employed. The mixtures were directly subjected to 4% polyacrylamide gel electrophoresis. The rovA gene was used as negative control.