The absence of an immediate upstream promoter region for the P. aeruginosa PAO1 gene rhlC was supported by the total lack of beta-gal reporter activity and complete mRNA binding of an upstream probe in RNase protection assays. However, protection assays were also performed on the putative gene PA1131 (immediately upstream of rhlC), and a single start site was identified, suggesting rhlC and PA1131 are organized in an operon. RNase protection of start site regions for both rhlC and PA1131 were performed with rhlR, lasR, and rhlR/lasR mutant PAO1 strains, which demonstrated identical expression patterns of strong, limited, and total loss (respectively) for each. This indicated strong up-regulation by rhlR and independent, meager up-regulation by lasR, and further supported rhlC/PA1131 activity as an operon. Expression patterns were identical to a comparative assay of the PAO1 rhlAB operon, known to be recognized by rhlR and lasR. Sequence alignment of the PA1131 and rhlA promoter regions confirmed a conserved lux box and rpoN consensus region.
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|