Mutation of pfm affects the adherence of Pseudomonas aeruginosa to host cells and the quorum sensing system.

The Pseudomonas aeruginosa quorum sensing (QS) system is controlled by the signal molecules acyl homoserine lactones (AHLs) that are synthesized from acyl enoyl-acyl carrier proteins (acyl-ACPs) provided by the fatty acid biosynthesis cycle. Pfm (PA2950), an enoyl-CoA reductase, has previously been shown to affect swimming mobility and fatty acid biosynthesis. In this report, we further show that pfm influences bacterial adherence to human cells. Microarray assay results suggest that pfm affects bacterial adherence through its influence on the QS system. Further experiments confirmed that the pfm mutant strain produces significantly less QS signal molecules than the corresponding wild-type strain. Using strains Escherichia coli DH5α(pECP64, lasB'-lacZ) and E. coli DH5α(pECP61.5, rhlA'-lacZ), biosensors for N-(3-oxododecanoyl) homoserine lactone (3O-C(12) -HSL) and N-butyryl homoserine lactone (C(4) -HSL), respectively, we found that pfm mutant strain produces decreased amounts of both signal molecules. Elastase activity and pyocyanin measurements further confirmed the reduced levels of 3O-C(12) -HSL and C(4) -HSL in the pfm mutant. Finally, bacterial virulence, as assessed by the Caenorhabditis elegans worm killing assay, is decreased in the pfm mutant. Taken together, these data indicate that pfm can be an important target for the control of P. aeruginosa infectivity.