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 coliDH5α(pECP64, lasB’-lacZ) and E. coliDH5α(pECP61.5, rhlA’-lacZ), biosensors for

N-(3-oxododecanoyl) homoserine lactone (3O-C12-HSL) and N-butyryl homoserine lactone (C4-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-C12-HSL and C4-HSL in the pfm mutant. Finally, bacterial virulence, as IWR-1 nmr 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. Pseudomonas aeruginosa, a versatile Gram-negative selleck chemicals llc bacterium, is a major opportunistic human pathogen. It is present in almost all ecological niches, including soil, marshes, and coastal marine

habitats, as well as on plants and animal tissues (Hardalo & Edberg, 1997). The genome of P. aeruginosa strain PAO1 contains 6.3 million base pairs, with 5572 predicted open reading frames (ORFs) (Stover et al., 2000). The genome complexity of this organism reflects its evolutionary adaptation to various hosts and environmental Sitaxentan conditions (Dobrindt & Hacker, 2001). As an opportunistic human pathogen, P. aeruginosa is commonly found in hospitals and often causes chronic infections. Many factors contribute to its infectivity and pathogenicity. It encodes a series of virulent effectors, including flagella, pilus, exotoxin A, endotoxin, pigments, protease,

etc. (Bell & Robinson, 2007; Harrison, 2007; Vanegas et al., 2009). It also takes advantages of many antibiotic resistance pathways that are readily activated during host infection (Hancock, 1998). These characteristics make it difficult to completely cure patients infected by P. aeruginosa. In P. aeruginosa, there are two separate quorum sensing (QS) systems, lasR-lasI and rhlR-rhlI (Parsek & Greenberg, 2000). Both systems are controlled by autoinducer signal molecules, N-(3-oxododecanoyl) homoserine lactone (3O-C12-HSL) and N-butyryl homoserine lactone (C4-HSL), respectively (Parsek & Greenberg, 2000). In the lasR-lasI QS system, the signal molecule 3O-C12-HSL is synthesized by LasI. In turn, the accumulated 3O-C12-HSL acts as the ligand for its receptor LasR, leading to the activation of LasR. Activated LasR functions as a transcriptional activator to upregulate downstream target genes, most of which are associated with the virulence of P.