The RhlR quorum-sensing receptor controls Pseudomonas aeruginosa pathogenesis and biofilm development independently of its canonical homoserine lactone autoinducer
Fig 5
Cell-free culture fluids from the ΔrhlI mutant activate RhlR-dependent gene expression.
rhlA expression was measured using a chromosomally encoded PrhlA- mNeonGreen transcriptional reporter. Gray bars represent rhlA reporter activity when rhlR was induced in the ΔlasR ΔlasI ΔrhlR ΔrhlI (i.e., Δ4 PBAD-rhlR) strain with 0.1% L-arabinose in the presence of 1% DMSO, 10 μM C4-HSL, 10 μM 3OC12-HSL, or 50 μM PQS. DMSO was used as the solvent for C4-HSL, 3OC12-HSL, and PQS. The rhlA reporter activity was set to 100% when 10 μM C4-HSL was added. In the cultures represented by the black bars, PrhlA-mNeonGreen was monitored in response to 20% (v/v) of the indicated cell-free culture fluids subjected to the specified treatments. Error bars represent SEM for three biological replicates.