Structure of the autoinducer required for expression of Pseudomonas aeruginosa virulence genes.

Abstract

In Pseudomonas aeruginosa the LasR protein is required for activation of lasB and several other virulence genes. A diffusible signal molecule, the P. aeruginosa autoinducer (PAI), produced by the bacterial cel and released into the growth medium, is required for activity ofLasR. By cloning a lasB::lacZ fusion and a lasR gene under control of the lac promoter in Escherichia coli, we have developed a quantitative bioassay for PAI. We have used this assay to foUlow the purification of PAI from cel-free culture supernatant fluids in which P. aeruginosa or E. coli containing the P. aeruginosa gene required for autoinducer synthesis, lasI, had been grown. Chemical analyses indicated the purified material was 3-oxo-N-(tetrahydro-2-oxo-3-furanyl)dodecanamide. To confirm this assignment, the compound was synthesized and the synthetic compound was shown to have chemical and biological properties identical to those of PAI purified from culture supernatant fluids. The elucidation of the PAI structure suggests therapeutic approaches toward control of P. aeruginosa infections.

Pseudomonas aeruginosa las and rhl quorum-sensing systems are important for infection and inflammation in a rat prostatitis model

“…AHLs, synthesized by bacterial cells, diffuse in and out of cells, binding a transcriptional regulator once a threshold concentration of bacteria is reached. In the las system, LasI synthesizes the AHL signal, N-3-oxo-dodecanoylhomoserine lactone, and LasR acts as the transcriptional regulator (Gambello & Iglewski, 1991;Passador et al, 1993;Pearson et al, 1994). For the rhl system, RhlI and RhlR are the synthase and transcriptional regulator, respectively, for the AHL signal, N-butyrylhomoserine lactone (Ochsner et al, 1994;Ochsner & Reiser, 1995;Pearson et al, 1995).…”

Mouse and Human Cell Activation by N -Dodecanoyl- dl -Homoserine Lactone, a Chromobacterium violaceum Autoinducer

“…In P. aeruginosa, two acyl-homoserine lactone-based systems, the las and rhl systems, have been described (10,12,14). Apart from its quorum-sensing function, the P. aeruginosa N-3-oxododecanoyl-homoserine lactone (3-oxo-C 12 -HSL) autoinducer has been suggested to modulate the immune responses of the infected host.…”

“…These are stably transformed RAW264.7 cells that express luciferase in an NF-B-dependent manner (7). RAW/kB cells were stimulated at 37°C for 6 h with C 4 -, C 6 -, C 7 -, C 8 -, C 10 -, C 12 -, and C 14 -HSLs, and luciferase activity was measured (Fig. 3).…”

AiiA, an enzyme that inactivates the acylhomoserine lactone quorum-sensing signal and attenuates the virulence of Erwinia carotovora

“…In recent years, AIs have been identified in several Gram-negative bacteria. AIs are involved in the regulation of a range of biological functions, including Ti plasmid conjugal transfer in Agrobacterium tumefaciens (3), induction of virulence genes in Erwinia carotovora, Erwinia chrysanthemi, Erwinia stewartii, Pseudomonas aeruginosa, Pseudomonas solanacearum, and Xenorhabdus nematophilus (4)(5)(6)(7)(8)(9)(10)(11)(12), regulation of antibiotic production in Pseudomonas aureofaciens and E. carotovora (10,13), regulation of swarming motility in Serratia liquefaciens (14), and biofilm formation in Pseudomonas fluorescens and P. aeruginosa (15,16). Many more bacterial species are known to produce AIs, but the relevant biological functions have not yet been established (17)(18)(19).…”