plasminogen-activator-inhibitor-2 and 2-heptyl-3-hydroxy-4-quinolone

Cis-2-dodecenoic acid (BDSF) is well known for its important functions in intraspecies signaling in Burkholderia cenocepacia. Previous work has also established an important role of BDSF in interspecies and inter-kingdom communications. It was identified that BDSF modulates virulence of Pseudomonas aeruginosa. However, how BDSF interferes with virulence of P. aeruginosa is still not clear.. We report here that BDSF mediates the cross-talk between B. cenocepacia and P. aeruginosa through interference with quorum sensing (QS) systems and type III secretion system (T3SS) of P. aeruginosa. Bioassay results revealed that exogenous addition of BDSF not only reduced the transcriptional expression of the regulator encoding gene of QS systems, i.e., lasR, pqsR, and rhlR, but also simultaneously decreased the production of QS signals including 3-oxo-C12-HSL, Pseudomonas quinolone signal (PQS) and C4-HSL, consequently resulting in the down-regulation of biofilm formation and virulence factor production of P. aeruginosa. Furthermore, BDSF and some of its derivatives are also capable of inhibiting T3SS of P. aeruginosa at a micromolar level. Treatment with BDSF obviously reduced the virulence of P. aeruginosa in both HeLa cell and zebrafish infection models.. These results depict that BDSF modulates virulence of P. aeruginosa through interference with QS systems and T3SS.

Topics: 4-Butyrolactone; Animals; Antibiosis; Bacterial Secretion Systems; Biofilms; Burkholderia cenocepacia; Disease Models, Animal; Epithelial Cells; Fatty Acids, Monounsaturated; Gene Expression Profiling; HeLa Cells; Homoserine; Humans; Pseudomonas aeruginosa; Pseudomonas Infections; Quinolones; Quorum Sensing; Signal Transduction; Virulence; Virulence Factors; Zebrafish

The autoinducer (AI) that initiates the quorum sensing (QS) signaling cascade in Pseudomonas aeruginosa is an acyl-homoserine lactone (acyl-HSL). We initiated a study of the requirements for binding of the AI to its protein effector LasR by synthesizing a library of analogs with the HSL moiety replaced with different amines and alcohols. We tested each compound for both agonist and antagonist activity using a QS-controlled reporter gene assay and found several new agonists and antagonists. A representative antagonist was further tested for its ability to inhibit virulence factors. This data progresses our understanding of the LasR-AI interaction toward the rational design of therapeutic inhibitors of QS.

Topics: 4-Butyrolactone; Aminophenols; Bacterial Proteins; Biofilms; DNA-Binding Proteins; Drug Design; Gene Library; Genes, Reporter; Genetic Techniques; Homoserine; Lactones; Molecular Structure; Pseudomonas aeruginosa; Quinolones; Signal Transduction; Structure-Activity Relationship; Trans-Activators; Virulence Factors

In Pseudomonas aeruginosa, diverse exoproduct virulence determinants are regulated via N-acylhomoserine lactone-dependent quorum sensing. Here we show that 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS) is also an integral component of the quorum sensing circuitry and is required for the production of rhl-dependent exoproducts at the onset of stationary phase. Analysis of spent P. aeruginosa culture supernatants revealed that PQS is produced at the end of exponential phase in the parent strain and in the late stationary phase of a lasR mutant. Mutants defective in both PQS production (pqsR-) and response (pqsE-) produced substantially reduced levels of exoproducts but retained wild-type N-butanoyl homoserine lactone (C4-HSL) levels. In the wild type, provision of exogenous PQS at the time of inoculation significantly increased PA-IL lectin, pyocyanin and elastase production during early stationary phase and promoted biofilm formation. Exogenous PQS but not PQS derivatives lacking the 3-hydroxy group overcame the cell density but not growth phase-dependent production of exoproducts. PQS also overcame the transcriptional and post-transcriptional repression of lecA (which codes for the PA-IL lectin) mediated via the negative regulators MvaT and RsmA respectively. Increased expression of lecA in the presence of exogenous PQS can be explained partially by increases in RhlR, RpoS and C4-HSL levels. A refined model for quorum sensing in P. aeruginosa is presented.

Topics: 4-Butyrolactone; Adaptation, Biological; Artificial Gene Fusion; Bacterial Proteins; Biofilms; DNA-Binding Proteins; Gene Deletion; Gene Expression Regulation, Bacterial; Genes, Bacterial; Genes, Reporter; Lectins; Mutagenesis, Insertional; Pseudomonas aeruginosa; Pyocyanine; Quinolones; Regulon; Sigma Factor; Signal Transduction; Trans-Activators; Virulence Factors

Topics: 4-Butyrolactone; Bacterial Proteins; Diketopiperazines; DNA-Binding Proteins; Homoserine; Ligases; Piperazines; Pseudomonas aeruginosa; Quinolones; Signal Transduction; Trans-Activators; Transcription Factors