Figure 3

Advancement of quorum-controlled gene expression. A. Venn diagram showing the numbers of genes significantly induced by acyl-HSL addition or by early expression of LasR, RhlR, or RpoS. Comparison was relative to the PAO1 parent strain without exogenous signal in logarithmic phase. B. Top panel, P. aeruginosa transcript profiles (absolute GeneChip signal levels) of all previously identified 315 quorum-activated genes [8] under various growth and expression conditions. Strains were incubated in the presence of arabinose with or without 2 μM 3OC12-HSL and 10 μM C4-HSL. Lane 1, PAO1 parent without signals in logarithmic phase (50 mM arabinose); lane 2, PAO1 parent with signals in logarithmic phase (50 mM arabinose); lane 3, lasR, rhlR mutant expressing lasR with signals in logarithmic phase (7.5 mM arabinose); lane 4, lasR, rhlR mutant expressing rhlR with signals in logarithmic phase (50 mM arabinose); lane 5, rpoS mutant expressing rpoS with signals in logarithmic phase (25 mM arabinose); lane 6, wildtype without signals in stationary phase (1 mM arabinose). Bottom panel, immunoblots showing the corresponding protein levels of LasR, RhlR and RpoS under the conditions described above. C and D, Transcript profiles of individual genes enlarged from B.