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Review
. 2025 May 14:15:1575421.
doi: 10.3389/fcimb.2025.1575421. eCollection 2025.

Analysing the integrated quorum sensing system its potential role in Pseudomonas aeruginosa pathogenesis

Juan Raya  1   2 , Enrique-J Montagut  1   2 , M-Pilar Marco  1   2
Affiliations
Review

Analysing the integrated quorum sensing system its potential role in Pseudomonas aeruginosa pathogenesis

Juan Raya et al. Front Cell Infect Microbiol. .

Erratum in

Abstract

Since its discovery, Quorum Sensing (QS), a form of bacterial communication, has been the focus of numerous studies aimed at unravelling the mechanisms behind this intricate process. Bacterial QS relies on releasing low molecular weight signals known as autoinducers (AIs). When these AIs reach a threshold concentration, they activate coordinated genetic expression of pathogenic and bacterial survival mechanisms. Pseudomonas aeruginosa's QS has been extensively studied due to its incidence and clinical significance in a wide range of human infections. Several decades ago, three QS systems, named Las, Rhl, and Pqs, were identified and have since then become the focus of numerous research studies and the target of innovative diagnostic and therapeutic strategies. However, a fourth QS-related system was more recently proposed that it has been the subject of debate. Named "integrated quorum sensing" (Iqs), interconnects the previously mentioned systems with the phosphate stress response. The associated AI has been identified as 2-(2-hydroxyphenyl)-thiazole-4-carbaldehyde, also known as IQS. This discovery has sparked a controversial discussion about its biosynthetic origin and whether it truly functions as an intercellular communication system. In this review, we critically discuss the different hypotheses, and its biological relevance while presenting key findings of the Iqs system.

Keywords: IQS; P. aeruginosa; aeruginaldehyde; autoinducers; quorum sensing.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Schematic representation of the four QS networks in P. aeruginosa. The four autoinducer synthases produce the autoinducers, 3-oxo-C12-HSL, C4-HSL, PQS, and IQS. 3-oxo-C12-HSL, C4-HSL, and PQS are recognized by the receptors placed in the cytoplasm. The receptor for IQS is currently unknown.
Figure 2
Figure 2
Schematic representation of the synthesis process of the antimetabolite AMB. Figure adapted from Murica et. al.
Figure 3
Figure 3
Biosynthesis pathway of PCH in P. aeruginosa. Dihydroaeruginoic acid is released during the assembly between PchE and PchF and can be transformed into IQS through simple dehydration.
Figure 4
Figure 4
Schematic summary of the evidence for which it is believed that IQS is synthesized by the amb or pch gene cluster.
Figure 5
Figure 5
Schematic representation of the QS-related genes induced by the PhoB regulon under phosphate depletion.
See this image and copyright information in PMC

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