A consensus search of the promoter region of spxB (the activity of which results in H2O2 production) identified two putative catabolite-responsive elements (CRE1 and CRE2), the binding sites for ccpA. H2O2 production assays and qRT-PCR of wild type and ccpA mutant strains were carried out in glucose- and oxygen-variable cultures; data indicated ccpA represses spxB in the presence of glucose, but only in aerobic conditions. Site-directed mutations of the CRE’s individually and together, along with CRE deletion, were analyzed against the wild type by EMSA, H2O2 production, and qRT-PCR. Binding and repression were shone for both singular CRE1 and CRE2 mutants, with no binding for CRE1+2 and deletion mutants. CRE1 and CRE2 mutants displayed permanent repression even in the absence of glucose.
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|