The Pseudomonas aeruginosa quinolone signal molecule overcomes the cell density-dependency of the quorum sensing hierarchy, regulates rhl-dependent genes at the onset of stationary phase and can be produced in the absence of LasR

ABSTRACT Pseudomonas aeruginosa uses quorum sensing (QS) to regulate the production of a battery of secreted products. At least some of these products are shared among the population and serve as public goods. When P. aeruginosa is grown on casein as the sole carbon and energy source, the QS-induced extracellular protease elastase is required for growth. We isolated a P. aeruginosa variant, which showed increased production of QS-induced factors after repeated transfers in casein broth. This variant, P. aeruginosa QS*, had a mutation in the glutathione synthesis gene gshA. We describe several experiments that show a gshA coding variant and glutathione affect the QS response. The P. aeruginosa QS transcription factor LasR has a redox-sensitive cysteine (C79). We report that GshA variant cells with a LasR C79S substitution show a similar QS response to that of wild-type P. aeruginosa. Surprisingly, it is not LasR but the QS transcription factor RhlR that is more active in bacteria containing the variant gshA. Our results demonstrate that QS integrates information about cell density and the cellular redox state via glutathione levels. IMPORTANCE Pseudomonas aeruginosa and other bacteria coordinate group behaviors using a chemical communication system called quorum sensing (QS). The QS system of P. aeruginosa is complex, with several regulators and signals. We show that decreased levels of glutathione lead to increased gene activation in P. aeruginosa, which did not occur in a strain carrying the redox-insensitive variant of a transcription factor. The ability of P. aeruginosa QS transcription factors to integrate information about cell density and cellular redox state shows these transcription factors can fine-tune levels of the gene products they control in response to at least two types of signals or cues.

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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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Immunometabolic hijacking of immune cells by a Pseudomonas aeruginosa quorum-sensing signal

10.1101/2021.10.03.462785 ◽

2021 ◽

Author(s):

Arunava Bandyopadhaya ◽

Vijay K Singh ◽

Arijit Chakraborty ◽

A. Aria Tzika ◽

Laurence G Rahme

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Immune Cells ◽

Metabolic Pathways ◽

Metabolic Reprogramming ◽

Signal Molecule ◽

Host Immune Responses ◽

Pathogen Persistence ◽

Mitochondrial Pyruvate Carrier ◽

Inflammatory Milieu

AbstractMacrophages utilize metabolic pathways to generate energy and metabolites that may be vulnerable to pathogen hijacking to favor pathogen survival and persistence. It is unclear how bacterial pathogens alter metabolic pathways in immune cells for their benefit and persistence in the infected host. We have shown that the Pseudomonas aeruginosa quorum sensing (QS) signal molecule 2-aminoacetophenone (2-AA) allows pathogen persistence in host tissues by triggering host tolerization via histone deacetylase (HDAC)1-mediated epigenetic reprogramming. Here, we provide strong evidence that 2-AA-meditated persistence is linked to specific metabolic pathway alterations that reduce energy availability and biosynthetic macromolecules involved in host immune responses. 2-AA promotes a Warburg-like metabolic reprogramming effect, thereby increasing levels of lactate, which repressed inflammatory signaling in macrophages. Moreover, it interferes with pyruvate translocation to mitochondria, reducing mitochondrial (mt)-oxidative phosphorylation (OXPHOS) due to down-regulation of estrogen-regulated receptor (ERR)α and mitochondrial pyruvate carrier (MPC)-1. This metabolic reprogramming dampened energy production, reduced the acetyl-CoA pool, and generated an anti-inflammatory milieu that favors P. aeruginosa persistence. These findings provide evidence of first-in-class metabolic reprogramming in immune cells mediated by a QS signaling molecule. The specific metabolic programs affected provide insights that may guide the design and development of therapeutics and protective interventions against pathogen-induced immunometabolic alterations and persistence factors.

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Signal Synthase-Type versus Catabolic Monooxygenases: Retracing 3-Hydroxylation of 2-Alkylquinolones and Their N-Oxides by Pseudomonas aeruginosa and Other Pulmonary Pathogens

Applied and Environmental Microbiology ◽

10.1128/aem.02241-20 ◽

2021 ◽

Vol 87 (6) ◽

Author(s):

Niklas H. Ritzmann ◽

Steffen L. Drees ◽

Susanne Fetzner

Keyword(s):

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Efflux Pump ◽

Biological Activities ◽

Multidrug Efflux Pump ◽

Therapeutic Success ◽

Signal Molecule ◽

Physiological Level ◽

Content Type

ABSTRACT The multiple biological activities of 2-alkylquinolones (AQs) are crucial for virulence of Pseudomonas aeruginosa, conferring advantages during infection and in polymicrobial communities. Whereas 2-heptyl-3-hydroxyquinolin-4(1H)-one (the “Pseudomonas quinolone signal” [PQS]) is an important quorum sensing signal molecule, 2-alkyl-1-hydroxyquinolin-4(1H)-ones (also known as 2-alkyl-4-hydroxyquinoline N-oxides [AQNOs]) are antibiotics inhibiting respiration. Hydroxylation of the PQS precursor 2-heptylquinolin-4(1H)-one (HHQ) by the signal synthase PqsH boosts AQ quorum sensing. Remarkably, the same reaction, catalyzed by the ortholog AqdB, is used by Mycobacteroides abscessus to initiate degradation of AQs. The antibiotic 2-heptyl-1-hydroxyquinolin-4(1H)-one (HQNO) is hydroxylated by Staphylococcus aureus to the less toxic derivative PQS-N-oxide (PQS-NO), a reaction probably also catalyzed by a PqsH/AqdB ortholog. In this study, we provide a comparative analysis of four AQ 3-monooxygenases of different organisms. Due to the major impact of AQ/AQNO 3-hydroxylation on the biological activities of the compounds, we surmised adaptations on the enzymatic and/or physiological level to serve either the producer or target organisms. Our results indicate that all enzymes share similar features and are incapable of discriminating between AQs and AQNOs. PQS-NO, hence, occurs as a native metabolite of P. aeruginosa although the unfavorable AQNO 3-hydroxylation is minimized by export as shown for HQNO, involving at least one multidrug efflux pump. Moreover, M. abscessus is capable of degrading the AQNO heterocycle by concerted action of AqdB and dioxygenase AqdC. However, S. aureus and M. abscessus orthologs disfavor AQNOs despite their higher toxicity, suggesting that catalytic constraints restrict evolutionary adaptation and lead to the preference of non-N-oxide substrates by AQ 3-monooxygenases. IMPORTANCE Pseudomonas aeruginosa, Staphylococcus aureus, and Mycobacteroides abscessus are major players in bacterial chronic infections and particularly common colonizers of cystic fibrosis (CF) lung tissue. Whereas S. aureus is an early onset pathogen in CF, P. aeruginosa establishes at later stages. M. abscessus occurs at all stages but has a lower epidemiological incidence. The dynamics of how these pathogens interact can affect survival and therapeutic success. 2-Alkylquinolone (AQ) and 2-alkylhydroxyquinoline N-oxide (AQNO) production is a major factor of P. aeruginosa virulence. The 3-position of the AQ scaffold is critical, both for attenuation of AQ toxicity or degradation by competitors, as well as for full unfolding of quorum sensing. Despite lacking signaling functionality, AQNOs have the strongest impact on suppression of Gram-positives. Because evidence for 3-hydroxylation of AQNOs has been reported, it is desirable to understand the extent by which AQ 3-monooxygenases contribute to manipulation of AQ/AQNO equilibrium, resistance, and degradation.

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Ethanol Stimulates Trehalose Production through a SpoT-DksA-AlgU-Dependent Pathway inPseudomonas aeruginosa

Journal of Bacteriology ◽

10.1128/jb.00794-18 ◽

2019 ◽

Vol 201 (12) ◽

Cited By ~ 6

Author(s):

Colleen E. Harty ◽

Dorival Martins ◽

Georgia Doing ◽

Dallas L. Mould ◽

Michelle E. Clay ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Cell Density ◽

Sigma Factor ◽

Strong Support ◽

Transcriptional Response ◽

Exponential Phase ◽

Fermentation Products ◽

Content Type ◽

In Cells

ABSTRACTPseudomonas aeruginosafrequently resides among ethanol-producing microbes, making its response to the microbially produced concentrations of ethanol relevant to understanding its biology. Our transcriptome analysis found that genes involved in trehalose metabolism were induced by low concentrations of ethanol, and biochemical assays showed that levels of intracellular trehalose increased significantly upon growth with ethanol. The increase in trehalose was dependent on the TreYZ pathway but not other trehalose-metabolic enzymes (TreS or TreA). The sigma factor AlgU (AlgT), a homolog of RpoE in other species, was required for increased expression of thetreZgene and trehalose levels, but induction was not controlled by the well-characterized proteolysis of its anti-sigma factor, MucA. Growth with ethanol led to increased SpoT-dependent (p)ppGpp accumulation, which stimulates AlgU-dependent transcription oftreZand other AlgU-regulated genes through DksA, a (p)ppGpp and RNA polymerase binding protein. Ethanol stimulation of trehalose also required acylhomoserine lactone (AHL)-mediated quorum sensing (QS), as induction was not observed in a ΔlasRΔrhlRstrain. A network analysis using a model, eADAGE, built from publicly availableP. aeruginosatranscriptome data sets (J. Tan, G. Doing, K. A. Lewis, C. E. Price, et al., Cell Syst 5:63–71, 2017, https://doi.org/10.1016/j.cels.2017.06.003) provided strong support for our model in whichtreZand coregulated genes are controlled by both AlgU- and AHL-mediated QS. Consistent with (p)ppGpp- and AHL-mediated quorum-sensing regulation, ethanol, even when added at the time of culture inoculation, stimulatedtreZtranscript levels and trehalose production in cells from post-exponential-phase cultures but not in cells from exponential-phase cultures. These data highlight the integration of growth and cell density cues in theP. aeruginosatranscriptional response to ethanol.IMPORTANCEPseudomonas aeruginosais often found with bacteria and fungi that produce fermentation products, including ethanol. At concentrations similar to those produced by environmental microbes, we found that ethanol stimulated expression of trehalose-biosynthetic genes and cellular levels of trehalose, a disaccharide that protects against environmental stresses. The induction of trehalose by ethanol required the alternative sigma factor AlgU through DksA- and SpoT-dependent (p)ppGpp. Trehalose accumulation also required AHL quorum sensing and occurred only in post-exponential-phase cultures. This work highlights how cells integrate cell density and growth cues in their responses to products made by other microbes and reveals a new role for (p)ppGpp in the regulation of AlgU activity.

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Conversion of the Pseudomonas aeruginosa Quinolone Signal and Related Alkylhydroxyquinolines by Rhodococcus sp. Strain BG43

Applied and Environmental Microbiology ◽

10.1128/aem.02342-14 ◽

2014 ◽

Vol 80 (23) ◽

pp. 7266-7274 ◽

Cited By ~ 14

Author(s):

Christine Müller ◽

Franziska S. Birmes ◽

Heiko Niewerth ◽

Susanne Fetzner

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Rhodococcus Erythropolis ◽

Opportunistic Pathogen ◽

Biosynthetic Enzyme ◽

Signal Molecule ◽

Content Type ◽

Cell Extracts ◽

Specific Pathway ◽

Rhodococcus Sp

ABSTRACTA bacterial strain, which based on the sequences of its 16S rRNA,gyrB,catA, andqsdAgenes, was identified as aRhodococcussp. closely related toRhodococcus erythropolis, was isolated from soil by enrichment on thePseudomonasquinolone signal [PQS; 2-heptyl-3-hydroxy-4(1H)-quinolone], a quorum sensing signal employed by the opportunistic pathogenPseudomonas aeruginosa. The isolate, termedRhodococcussp. strain BG43, cometabolically degraded PQS and its biosynthetic precursor 2-heptyl-4(1H)-quinolone (HHQ) to anthranilic acid. HHQ degradation was accompanied by transient formation of PQS, and HHQ hydroxylation by cell extracts required NADH, indicating that strain BG43 has a HHQ monooxygenase isofunctional to the biosynthetic enzyme PqsH ofP. aeruginosa. The enzymes catalyzing HHQ hydroxylation and PQS degradation were inducible by PQS, suggesting a specific pathway. Remarkably,Rhodococcussp. BG43 is also capable of transforming 2-heptyl-4-hydroxyquinoline-N-oxide to PQS. It thus converts an antibacterial secondary metabolite ofP. aeruginosato a quorum sensing signal molecule.

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The Pseudomonas aeruginosa quorum sensing signal molecule N-(3-oxododecanoyl) homoserine lactone enhances keratinocyte migration and induces Mmp13 gene expression in vitro

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2012.09.037 ◽

2012 ◽

Vol 427 (2) ◽

pp. 273-279 ◽

Cited By ~ 9

Author(s):

Camila Paes ◽

Gojiro Nakagami ◽

Takeo Minematsu ◽

Takashi Nagase ◽

Lijuan Huang ◽

...

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Homoserine Lactone ◽

Signal Molecule ◽

Keratinocyte Migration

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

Molecular Microbiology ◽

10.1046/j.1365-2958.1998.00789.x ◽

2002 ◽

Vol 28 (1) ◽

pp. 193-203 ◽

Cited By ~ 61

Author(s):

Yan Jiang ◽

Miguel Camara ◽

Siri Ram Chhabra ◽

Kim R. Hardie ◽

Barrie W. Bycroft ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Homoserine Lactone ◽

Signal Molecule ◽

In Vitro Biosynthesis

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Regulation of rpoS Gene Expression in Pseudomonas: Involvement of a TetR Family Regulator

Journal of Bacteriology ◽

10.1128/jb.183.12.3712-3720.2001 ◽

2001 ◽

Vol 183 (12) ◽

pp. 3712-3720 ◽

Cited By ~ 55

Author(s):

Milan Kojic ◽

Vittorio Venturi

Keyword(s):

Gene Expression ◽

Gene Regulation ◽

Quorum Sensing ◽

Stationary Phase ◽

Cell Density ◽

Promoter Activity ◽

Regulatory Protein ◽

Insertion Mutant ◽

Regulatory Cascade ◽

A Cell

ABSTRACT The rpoS gene encodes the sigma factor which was identified in several gram-negative bacteria as a central regulator during stationary phase. rpoS gene regulation is known to respond to cell density, showing higher expression in stationary phase. For Pseudomonas aeruginosa, it has been demonstrated that the cell-density-dependent regulation response known as quorum sensing interacts with this regulatory response. Using therpoS promoter of P. putida, we identified a genomic Tn5 insertion mutant of P. putida which showed a 90% decrease in rpoSpromoter activity, resulting in less RpoS being present in a cell at stationary phase. Molecular analysis revealed that this mutant carried a Tn5 insertion in a gene, designatedpsrA (Pseudomonas sigma regulator), which codes for a protein (PsrA) of 26.3 kDa. PsrA contains a helix-turn-helix motif typical of DNA binding proteins and belongs to the TetR family of bacterial regulators. The homolog of thepsrA gene was identified in P. aeruginosa; the protein showed 90% identity to PsrA ofP. putida. ApsrA::Tn5 insertion mutant ofP. aeruginosa was constructed. In bothPseudomonas species, psrA was genetically linked to the SOS lexA repressor gene. Similar to what was observed for P. putida, a psrA null mutant of P. aeruginosa also showed a 90% reduction inrpoS promoter activity; both mutants could be complemented for rpoS promoter activity when thepsrA gene was provided in trans.psrA mutants of both Pseudomonas species lost the ability to induce rpoS expression at stationary phase, but they retained the ability to produce quorum-sensing autoinducer molecules. PsrA was demonstrated to negatively regulatepsrA gene expression in Pseudomonas and in Escherichia coli as well as to be capable of activating the rpoS promoter in E. coli. Our data suggest that PsrA is an important regulatory protein ofPseudomonas spp. involved in the regulatory cascade controlling rpoS gene regulation in response to cell density.

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