Representation depicting the role of Fur and H-NS in the regulation of ftnB and the tdc operon. H-NS confirmed binding sites and transcriptional repression  were compared with our microarray data and Fur repression of hns . Collectively, the data indicate that Fur-dependent activation of ftnB and the tdc operon may be due to the increased expression of H-NS in Δfur, which represses ftnB and the tdc operon. Thus, under Fur active conditions (left panel), hns is repressed by Fur thereby blocking H-NS repression of ftnB and the tdc operon (signified by the circle with an "X"). While under Fur inactive conditions (right panel), the overexpression of H-NS results in the repression of ftnB and the tdc operon under anaerobic conditions.