FIG. 2.
Zinc-specific regulation of znuA and zur genes. (A) Effects of various divalent metals on znuA and zur transcripts. The wild-type and Δzur (S701) cells were grown in chelated minimal medium (NMMP medium incubated with Chelex-100 resin). Either EDTA (2 mM final concentration) or various metals (from Fe to Mn, at 25 μM) were added, and the cultures were incubated for 30 min before harvesting. Following S1 mapping, the amount of protected DNA probe was quantified by a phosphorimage analyzer (FLA-2000; Fuji). Representative results are presented with the quantified signal values. −, control. The signal intensity relative to that of the untreated control was presented. (B) Sensitivity of gene expression to exogenously added zinc. Cells were grown as described in the legend to panel A except that increasing amounts of ZnSO4 (final concentrations, 50 to 250 nM) were added to the culture for 30 min before cell harvesting. Representative results are presented with quantified signal values.