The RhlR quorum-sensing receptor controls Pseudomonas aeruginosa pathogenesis and biofilm development independently of its canonical homoserine lactone autoinducer
Fig 3
P. aeruginosa has distinct RhlR and RhlI regulons.
A) Venn diagram showing differentially expressed genes in the ΔrhlI and ΔrhlR P. aeruginosa PA14 strains at high cell density (denoted Planktonic Culture; OD600 = 2.0) and in colony biofilms grown on Congo red agar medium for 5 days (denoted Colony Biofilm). Blue circles represent differentially expressed genes in the ΔrhlR P. aeruginosa strain compared to the WT strain. Orange circles indicate differentially expressed genes in the ΔrhlI P. aeruginosa strain compared to the WT strain. Numbers of cDNA reads for annotated genes were compared to the WT strain under the same conditions. Statistically significant genes (P < 0.001) that changed >2-fold are shown (see S1 and S2 Tables). RNA-seq was performed on three biological replicates per strain and per condition. B) Relative expression of the representative phenazine biosynthesis genes phzA1 (black), phzF2 (dark gray), phzM (light gray), and phzH (checkered). Data are normalized to 16S RNA measured by qRT-PCR in WT, ΔrhlR, and ΔrhlI strains in high cell density (OD600 = 2.0) planktonic culture (top panel) and in colony biofilms on Congo red agar medium after 5 days (bottom panel). Error bars represent SD of three replicates. AU denotes arbitrary units. C) Colony biofilm morphology of the WT, Δphz, and the ΔrhlR Δphz, and ΔrhlI Δphz mutants. Scale bar is 2 mm.