Quorum Sensing Mechanisms in Pseudomonas Aeruginosa Infections

Pseudomonas aeruginosa employs a sophisticated quorum sensing network to coordinate the expression of virulence determinants, biofilm formation and antibiotic tolerance in response to cell density and environmental cues. This network comprises at least three interconnected systems: the LasI/LasR acyl-homoserine lactone module, the RhlI/RhlR acyl-homoserine lactone module and the Pseudomonas quinolone signal (PQS) module governed by the LysR-type regulator PqsR (also known as MvfR). LasR sits at the top of the hierarchy, activating rhl and pqs operons, while RhlR and PqsR exert both overlapping and distinct controls over genes encoding proteases, toxins, siderophores and matrix components. Clinical isolates often exhibit mutations in lasR yet maintain virulence via compensatory activation of RhlR or PqsR circuits, illustrating the plasticity of quorum sensing in acute and chronic infections. The interplay of these signals drives biofilm maturation, persistent infections in cystic fibrosis and immunocompromised hosts, and represents a prime target for anti-virulence therapies aimed at disarming rather than killing the pathogen.

Research from Nature Portfolio

Recent studies have elucidated how clinical isolates bearing inactivating mutations in the master regulator LasR recalibrate quorum sensing through altered synthase variants. Loss of LasR activity is offset by mutations in the RhlI synthase that boost production of its cognate autoinducer, restoring downstream signalling and virulence traits in acute infection models. This work reveals molecular mechanisms underpinning adaptive plasticity of the quorum sensing hierarchy within host environments.

Foundational investigations into the PqsR regulator have uncovered direct binding and regulation of a broad spectrum of virulence and defence genes beyond the canonical pqs operon. MvfR not only autoinduces alkyl-quinolone synthesis but also directly controls loci involved in oxidative stress response and antibiotic tolerance, challenging the linear model of quorum sensing and suggesting a circular regulatory architecture that integrates self-defence with virulence control.

Quorum Sensing Mechanisms in Pseudomonas Aeruginosa Infections publication trend

The graph below shows the total number of articles in quorum sensing mechanisms in pseudomonas aeruginosa infections across all publications each year (not limited to Nature Index journals).

Technical terms

Quorum sensing: bacterial cell-to-cell communication system that regulates gene expression in response to population density.

Autoinducer: small diffusible molecule produced by bacteria to signal community density and coordinate collective behaviours.

Biofilm: structured microbial community embedded in an extracellular matrix that confers protection from environmental stresses and antibiotics.

LasR: master transcriptional regulator of the primary acyl-homoserine lactone quorum sensing system in P. aeruginosa.

RhlR: transcriptional regulator of the secondary acyl-homoserine lactone quorum sensing system, acting downstream of LasR.

Pseudomonas quinolone signal (PQS): 2-alkyl-4-quinolone family signalling molecules that modulate virulence, iron acquisition and biofilm formation.

PqsR (MvfR): LysR-type transcriptional regulator that binds quinolone signals to control virulence gene expression and self-defence systems in P. aeruginosa.

References

1. Quorum-sensing synthase mutations re-calibrate autoinducer concentrations in clinical isolates of Pseudomonas aeruginosa to enhance pathogenesis. Nature Communications (2023).
2. Towards Translation of PqsR Inverse Agonists: From In Vitro Efficacy Optimization to In Vivo Proof‐of‐Principle. Advanced Science (2023).
3. New Evolutionary Insights into RpoA: A Novel Quorum Sensing Reprograming Factor in Pseudomonas aeruginosa. Molecular Biology and Evolution (2023).
4. LasR Variant Cystic Fibrosis Isolates Reveal an Adaptable Quorum-Sensing Hierarchy in Pseudomonas aeruginosa. mBio (2016).
5. The hierarchy quorum sensing network in Pseudomonas aeruginosa. Protein & Cell (2014).
6. Evidence for Direct Control of Virulence and Defense Gene Circuits by the Pseudomonas aeruginosa Quorum Sensing Regulator, MvfR. Scientific Reports (2016).