In vitro biosynthesis of the Pseudomonas aeruginosa quorum-sensing signal molecule N-butanoyl-L-homoserine lactone

Bacteria degrading the quorum-sensing (QS) signal molecule N-hexanoylhomoserine lactone were isolated from a tobacco rhizosphere. Twenty-five isolates degrading this homoserine lactone fell into six groups according to their genomic REP-PCR and rrs PCR-RFLP profiles. Representative strains from each group were identified as members of the genera Pseudomonas, Comamonas, Variovorax and Rhodococcus. All these isolates degraded N-acylhomoserine lactones other than the hexanoic acid derivative, albeit with different specificity and kinetics. One of these isolates, Rhodococcus erythropolis strain W2, was used to quench QS-regulated functions of other microbes. In vitro, W2 strongly interfered with violacein production by Chromobacterium violaceum, and transfer of pathogenicity in Agrobacterium tumefaciens. In planta, R. erythropolis W2 markedly reduced the pathogenicity of Pectobacterium carotovorum subsp. carotovorum in potato tubers. These series of results reveal the diversity of the QS-interfering bacteria in the rhizosphere and demonstrate the validity of targeting QS signal molecules to control pathogens with natural bacterial isolates.

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Azithromycin Inhibits MUC5AC Production Induced by the Pseudomonas aeruginosa Autoinducer N-(3-Oxododecanoyl) Homoserine Lactone in NCI-H292 Cells

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.9.3457-3461.2004 ◽

2004 ◽

Vol 48 (9) ◽

pp. 3457-3461 ◽

Cited By ~ 87

Author(s):

Yoshifumi Imamura ◽

Katsunori Yanagihara ◽

Yohei Mizuta ◽

Masafumi Seki ◽

Hideaki Ohno ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Bacterial Infection ◽

Core Protein ◽

Homoserine Lactone ◽

Signal Molecule ◽

Diffuse Panbronchiolitis ◽

Mucin Production ◽

Protein Levels ◽

Extracellular Signal

ABSTRACT The features of chronic airway diseases, including chronic bronchitis, cystic fibrosis, bronchiectasis, and diffuse panbronchiolitis, include chronic bacterial infection and airway obstruction by mucus. Pseudomonas aeruginosa is one of the most common pathogens in chronic lung infection, and quorum-sensing systems contribute to the pathogenesis of this disease. The quorum-sensing signal molecule [N-(3-oxododecanoyl) homoserine lactone (3O-C12-HSL)] not only regulates bacterial virulence but also is associated with the immune response. In this study, we investigated whether 3O-C12-HSL could stimulate the production of a major mucin core protein, MUC5AC. The effect of a macrolide on MUC5AC production was also studied. 3O-C12-HSL induced NCI-H292 cells to express MUC5AC at both the mRNA and the protein levels in time- and dose-dependent manners. A 15-membered macrolide, azithromycin, inhibited MUC5AC production that was activated by 3O-C12-HSL. 3O-C12-HSL induced extracellular signal-regulated kinase (ERK) 1/2 and I-κB phosphorylation in cells, and this induction was suppressed by azithromycin. 3O-C12-HSL-induced MUC5AC production was blocked by the ERK pathway inhibitor PD98059. Our findings suggest that the P. aeruginosa autoinducer 3O-C12-HSL contributes to excessive mucin production in chronic bacterial infection. Azithromycin seems to reduce this mucin production by interfering with intracellular signal transduction.

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Mechanistic analysis of a synthetic inhibitor of the Pseudomonas aeruginosa LasI quorum-sensing signal synthase

Scientific Reports ◽

10.1038/srep16569 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 29

Author(s):

O. Lidor ◽

A. Al-Quntar ◽

E. C. Pesci ◽

D. Steinberg

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

In Silico ◽

Biofilm Formation ◽

Homoserine Lactone ◽

Site Directed Mutagenesis ◽

Great Promise ◽

Acyl Homoserine Lactone ◽

Virulence Determinants

Abstract Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen responsible for many human infections. LasI is an acyl-homoserine lactone synthase that produces a quorum-sensing (QS) signal that positively regulates numerous P. aeruginosa virulence determinants. The inhibition of the LasI protein is therefore an attractive drug target. In this study, a novel in silico to in vitro complementation was applied to screen thiazolidinedione-type compounds for their ability to inhibit biofilm formation at concentrations not affecting bacterial growth. The compound (z)-5-octylidenethiazolidine-2, 4-dione (TZD-C8) was a strong inhibitor of biofilm formation and chosen for further study. Structural exploration of in silico docking predicted that the compound had high affinity for the LasI activity pocket. The TZD-C8 compound was also predicted to create hydrogen bonds with residues Arg30 and Ile107. Site-directed mutagenesis (SDM) of these two sites demonstrated that TZD-C8 inhibition was abolished in the lasI double mutant PAO-R30D, I107S. In addition, in vitro swarming motility and quorum sensing signal production were affected by TZD-C 8, confirming this compound alters the cell to cell signalling circuitry. Overall, this novel inhibitor of P. aeruginosa quorum sensing shows great promise and validates our mechanistic approach to discovering inhibitors of LuxI-type acyl-homoserine lactone synthases.

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A Distinct QscR Regulon in the Pseudomonas aeruginosa Quorum-Sensing Circuit

Journal of Bacteriology ◽

10.1128/jb.188.9.3365-3370.2006 ◽

2006 ◽

Vol 188 (9) ◽

pp. 3365-3370 ◽

Cited By ~ 144

Author(s):

Yannick Lequette ◽

Joon-Hee Lee ◽

Fouzia Ledgham ◽

Andrée Lazdunski ◽

E. Peter Greenberg

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Opportunistic Pathogen ◽

Homoserine Lactone ◽

Acyl Homoserine Lactone ◽

Signal Molecule ◽

Control Of Gene Expression ◽

Signaling Systems ◽

Sensing Systems

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa possesses two complete acyl-homoserine lactone (acyl-HSL) signaling systems. One system consists of LasI and LasR, which generate a 3-oxododecanoyl-homoserine lactone signal and respond to that signal, respectively. The other system is RhlI and RhlR, which generate butanoyl-homoserine lactone and respond to butanoyl-homoserine lactone, respectively. These quorum-sensing systems control hundreds of genes. There is also an orphan LasR-RhlR homolog, QscR, for which there is no cognate acyl-HSL synthetic enzyme. We previously reported that a qscR mutant is hypervirulent and showed that QscR transiently represses a few quorum-sensing-controlled genes. To better understand the role of QscR in P. aeruginosa gene regulation and to better understand the relationship between QscR, LasR, and RhlR control of gene expression, we used transcription profiling to identify a QscR-dependent regulon. Our analysis revealed that QscR activates some genes and represses others. Some of the repressed genes are not regulated by the LasR-I or RhlR-I systems, while others are. The LasI-generated 3-oxododecanoyl-homoserine lactone serves as a signal molecule for QscR. Thus, QscR appears to be an integral component of the P. aeruginosa quorum-sensing circuitry. QscR uses the LasI-generated acyl-homoserine lactone signal and controls a specific regulon that overlaps with the already overlapping LasR- and RhlR-dependent regulons.

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Albumin Inhibits Pseudomonas aeruginosa Quorum Sensing and Alters Polymicrobial Interactions

Infection and Immunity ◽

10.1128/iai.00116-17 ◽

2017 ◽

Vol 85 (9) ◽

Cited By ~ 25

Author(s):

Allie Clinton Smith ◽

Anne Rice ◽

Bryan Sutton ◽

Rebecca Gabrilska ◽

Aimee K. Wessel ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Chronic Wounds ◽

Homoserine Lactone ◽

Individual Species ◽

Content Type ◽

The Individual ◽

Chronic Wound Infections ◽

Isolated Species

ABSTRACT Polymicrobial interactions are complex and can influence the course of an infection, as is the case when two or more species exhibit a synergism that produces a disease state not seen with any of the individual species alone. Cell-to-cell signaling is key to many of these interactions, but little is understood about how the host environment influences polymicrobial interactions or signaling between bacteria. Chronic wounds are typically polymicrobial, with Staphylococcus aureus and Pseudomonas aeruginosa being the two most commonly isolated species. While P. aeruginosa readily kills S. aureus in vitro, the two species can coexist for long periods together in chronic wound infections. In this study, we investigated the ability of components of the wound environment to modulate interactions between P. aeruginosa and S. aureus. We demonstrate that P. aeruginosa quorum sensing is inhibited by physiological levels of serum albumin, which appears to bind and sequester some homoserine lactone quorum signals, resulting in the inability of P. aeruginosa to produce virulence factors that kill S. aureus. These data could provide important clues regarding the virulence of P. aeruginosa in albumin-depleted versus albumin-rich infection sites and an understanding of the nature of friendly versus antagonistic interactions between P. aeruginosa and S. aureus.

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Influence of Pseudomonas aeruginosa quorum sensing signal molecule N-(3-oxododecanoyl) homoserine lactone on mast cells

Medical Microbiology and Immunology ◽

10.1007/s00430-009-0111-z ◽

2009 ◽

Vol 198 (2) ◽

pp. 113-121 ◽

Cited By ~ 39

Author(s):

Hongtao Li ◽

Lili Wang ◽

Lu Ye ◽

Yan Mao ◽

Xuhua Xie ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Mast Cells ◽

Quorum Sensing ◽

Homoserine Lactone ◽

Signal Molecule

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Quorum Quenching by an N-Acyl-Homoserine Lactone Acylase from Pseudomonas aeruginosa PAO1

Infection and Immunity ◽

10.1128/iai.74.3.1673-1682.2006 ◽

2006 ◽

Vol 74 (3) ◽

pp. 1673-1682 ◽

Cited By ~ 214

Author(s):

Charles F. Sio ◽

Linda G. Otten ◽

Robbert H. Cool ◽

Stephen P. Diggle ◽

Peter G. Braun ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Quorum Quenching ◽

Homoserine Lactone ◽

Side Chain ◽

Signal Molecules ◽

Acyl Homoserine Lactone ◽

Beta Lactam ◽

Signal Molecule ◽

Pathogenic Potential

ABSTRACT The virulence of the opportunistic human pathogen Pseudomonas aeruginosa PAO1 is controlled by an N-acyl-homoserine lactone (AHL)-dependent quorum-sensing system. During functional analysis of putative acylase genes in the P. aeruginosa PAO1 genome, the PA2385 gene was found to encode an acylase that removes the fatty acid side chain from the homoserine lactone (HSL) nucleus of AHL-dependent quorum-sensing signal molecules. Analysis showed that the posttranslational processing of the acylase and the hydrolysis reaction type are similar to those of the beta-lactam acylases, strongly suggesting that the PA2385 protein is a member of the N-terminal nucleophile hydrolase superfamily. In a bioassay, the purified acylase was shown to degrade AHLs with side chains ranging in length from 11 to 14 carbons at physiologically relevant low concentrations. The substituent at the 3′ position of the side chain did not affect activity, indicating broad-range AHL quorum-quenching activity. Of the two main AHL signal molecules of P. aeruginosa PAO1, N-butanoyl-l-homoserine lactone (C4-HSL) and N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL), only 3-oxo-C12-HSL is degraded by the enzyme. Addition of the purified protein to P. aeruginosa PAO1 cultures completely inhibited accumulation of 3-oxo-C12-HSL and production of the signal molecule 2-heptyl-3-hydroxy-4(1H)-quinolone and reduced production of the virulence factors elastase and pyocyanin. Similar results were obtained when the PA2385 gene was overexpressed in P. aeruginosa. These results demonstrate that the protein has in situ quorum-quenching activity. The quorum-quenching AHL acylase may enable P. aeruginosa PAO1 to modulate its own quorum-sensing-dependent pathogenic potential and, moreover, offers possibilities for novel antipseudomonal therapies.

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Efficacy of Liposomal Bismuth-Ethanedithiol-Loaded Tobramycin after Intratracheal Administration in Rats with Pulmonary Pseudomonas aeruginosa Infection

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01634-12 ◽

2012 ◽

Vol 57 (1) ◽

pp. 569-578 ◽

Cited By ~ 26

Author(s):

Moayad Alhariri ◽

Abdelwahab Omri

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Virulence Factors ◽

Homoserine Lactone ◽

Protease Production ◽

Signal Molecules ◽

Acyl Homoserine Lactone ◽

Signal Molecule ◽

Intratracheal Administration ◽

Content Type

ABSTRACTWe sought to investigate alterations in quorum-sensing signal moleculeN-acyl homoserine lactone secretion and in the release ofPseudomonas aeruginosavirulence factors, as well as thein vivoantimicrobial activity of bismuth-ethanedithiol incorporated into a liposome-loaded tobramycin formulation (LipoBiEDT-TOB) administered to rats chronically infected withP. aeruginosa. The quorum-sensing signal moleculeN-acyl homoserine lactone was monitored by using a biosensor organism.P. aeruginosavirulence factors were assessed spectrophotometrically. An agar beads model of chronicPseudomonaslung infection in rats was used to evaluate the efficacy of the liposomal formulation in the reduction of bacterial count. The levels of active tobramycin in the lungs and the kidneys were evaluated by microbiological assay. LipoBiEDT-TOB was effective in disrupting both quorum-sensing signal moleculesN-3-oxo-dodeccanoylhomoserine lactone andN-butanoylhomoserine lactone, as well as significantly (P< 0.05) reducing lipase, chitinase, and protease production. At 24 h after 3 treatments, the CFU counts in lungs of animals treated with LipoBiEDT-TOB were of 3 log10CFU/lung, comparated to 7.4 and 4.7 log10CFU/lung, respectively, in untreated lungs and in lungs treated with free antibiotic. The antibiotic concentration after the last dose of LipoBiEDT-TOB was 25.1 μg/lung, while no tobramycin was detected in the kidneys. As for the free antibiotic, we found 6.5 μg/kidney but could not detect any tobramycin in the lungs. Taken together, LipoBiEDT-TOB reduced the production of quorum-sensing molecules and virulence factors and could highly improve the management of chronic pulmonary infection in cystic fibrosis patients.

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Pseudomonas aeruginosa Quorum Sensing MoleculeN-(3-Oxododecanoyl)-l-Homoserine-Lactone Induces HLA-G Expression in Human Immune Cells

Infection and Immunity ◽

10.1128/iai.00803-15 ◽

2015 ◽

Vol 83 (10) ◽

pp. 3918-3925 ◽

Cited By ~ 14

Author(s):

Daria Bortolotti ◽

Joel LeMaoult ◽

Claudio Trapella ◽

Dario Di Luca ◽

Edgardo D. Carosella ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Immune Cells ◽

U937 Cell ◽

Homoserine Lactone ◽

Interleukin 10 ◽

Luciferase Assay ◽

Enzyme Linked Immunosorbent Assay ◽

Content Type

HLA-G is a nonclassical class I human leukocyte antigen (HLA) involved in mechanisms of immune tolerance. The objective of this study was to determine whetherN-(3-oxododecanoyl)-l-homoserine lactone (3O-C12-HSL), a quorum sensing molecule produced byPseudomonas aeruginosa, could modify HLA-G expression to control the host immune response. We evaluated the ability of 3O-C12-HSL to induce HLA-G expression in primary immune cells, monocytes (U937 and THP1), and T-cell lines (Jurkat)in vitroand analyzed the cellular pathway responsible for HLA-G expression. We studied the HLA-G promoter with a luciferase assay and interleukin-10 (IL-10) and p38/CREB signaling with enzyme-linked immunosorbent assay and immunofluorescence, respectively. We observed that 3O-C12-HSL is able to induce HLA-G expression in human monocytes and T cells. We showed that the induction of HLA-G by 3O-C12-HSL is p38/CREB and IL-10 dependent. 3O-C12-HSL treatment is able to arrest only the U937 cell cycle, possibly due to the peculiar expression of the ILT2 receptor in the U937 cell line. Our observations suggest HLA-G as a mechanism to create a protected niche for the bacterial reservoir, similar to the role of HLA-G molecules during viral infections.

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