STRUCTURE OF THE AUTOINDUCER REQUIRED FOR EXPRESSION OF PSEUDOMONAS-AERUGINOSA VIRULENCE GENES

In Pseudomonas aeruginosa the LasR protein is required for activation of lasB and several other virulence genes. A diffusible signal molecul e, the P. aeruginosa autoinducer (PAI), produced by the bacterial cell and released into the growth medium, is required for activity of LasR . By cloning a lasB=lacZ fusion and a lasR gene under control of the l ac promoter in Escherichia coli, we have developed a quantitative bioa ssay for PAI. We have used this assay to follow the purification of PA I from cell-free culture supernatant fluids in which P. aeruginosa or E. coli containing the P. aeruginosa gene required for autoinducer syn thesis, lasI, had been grown. Chemical analyses indicated the purified material was 3-oxo-N-(tetrahydro-2-oxo-3-furanyl)dodecanamide. To con firm this assignment, the compound was synthesized and the synthetic c ompound was shown to have chemical and biological properties identical to those of PAI purified from culture supernatant fluids. The elucida tion of the PAI structure suggests therapeutic approaches toward contr ol of P. aeruginosa infections.