The results of qRT-PCR showed that iscR expression was upregulated under stressful conditions (upon treatment with plumbahin, organic hydroperoxides, dipyridyl, paraquat, menadione, H2O2 and high salt). The transcription start site of the iscR operon was mapped by primer extension. Visual inspection of the sequences upstream of the iscR transcription start revealed two putative type 1 IscR-binding motifs. These two motifs had 68% and 76% identity, respectively, to the consensus sequence for the E. coli type 1 IscR-binding motif. qRT-PCR showed that under uninduced conditions, the expression of iscR in the iscR mutant strain was 20.8-fold higher that in the wild-type PAO1. site-directed mutagenesis of amino acid residues involved in [2Fe-2S] ligation was performed to produce IscR variants. The IscR mutants showed lower levels of siderophore production compared with the strain producing wild-type IscR.
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|