Alterations in the extracellular proteome of human pathogen Pseudomonas aeruginosa in response to natural and modified N-acyl-L-homoserine lactones

The common opportunistic human pathogen Pseudomonas aeruginosa employs quorum sensing QS to regulate a large set of genes involved in virulence and host-pathogen interactions. The Las circuit positioned on the top of the QS hierarchy in P. aeruginosa, makes use of N-acyl-L-homoserine lactones (AHL) as signal molecules, like N-3-oxo-dodecanoyl-L-homoserine lactone (3O-C12-HSL). Here, a quantitative proteomic approach was used to study the effect of natural 3O-C12-HSL and four AHL analogues on the expression and excretion of QS-regulated extracellular proteins. Treatment with AHL compounds resulted in significant difference in appearance of the 3O-C12-HSL-responsive reference proteins related to QS communication and virulence, i.e., a distinct activity as QS modulators. In summary, 3O-C12-HSL has a profound effect on extracellular proteome involved in the pathogenicity of P. aeruginosa, and the four AHL analogues have achieved a distinct inhibitory effect on the extracellular proteome.