vvsA-luxAB reporter fusion showed that vvsA expression was highly increased in the smcR mutant compared to the wild type strain. RT-PCR showed that introduction of a wild-type smcR plasmid complemented the defect in vvsA transcription in the smcR mutant. Primer extension analysis determined the vvsA transcription start site. EMSA confirmed that SmcR binds specifically to the vvsA promoter. DNase I footprinting identified that SmcR protected a 22 bp region containing an inverted repeat sequence. 7 bases of the SmcR binding site were mutated by site-directed mutagenesis. LuxAB reporter assays with promoters containing wild-type and mutated SmcR binding sites showed that wild-type SmcR binding site was an essential cis-acting element for SmcR regulation of vvsA transcription.
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|