Western blot analysis showed FtnA levels are growth phase independent, but Fur and iron dependent, with expression levels lower in their presence. A ftna-lacZ translational fusion strand was used to further confirm the iron/fur dependence of FtnA expression. SdiA was shown to regulate ftnA, but is not responsible for its iron depletion induction. Western blot analysis showed that H-NS is required for fur-dependent regulation of FtnA. Fur dependent induction of ftnA expression requiring H-NS was confirmed by ftnA-lacZ expression comparison in wild type, hns, fur and hns fur strains. Gel retardation assays was used to show H-NS and Fur specifically interact with the ftnA promoter. In vitro transcription assays revealed Fur counteracts H-NS repression of FtnA transcription. DNAse I footprinting identified the location of the Fur binding sites and the H-NS binding sites in the ftnA binding region. A Fur H-NS combination footprinting reaction showed H-NS and Fur compete for the same region in the ftnA promoter.
Regulated genes for each binding site are displayed below. Gene regulation diagrams show binding sites, positively-regulated genes, negatively-regulated genes, both positively and negatively regulated genes, genes with unspecified type of regulation. For each indvidual site, experimental techniques used to determine the site are also given.
|Site sequence||Regulated genes||Gene diagram||Experimental techniques||TF function||TF type|