LuxR homolog-independent gene regulation by acyl-homoserine lactones in
            <i>Pseudomonas aeruginosa</i>

Chugani, Sudha; Greenberg, E. Peter

doi:10.1073/pnas.1005909107

Cited by 58 publications

(29 citation statements)

References 47 publications

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“…These delay the expression of quorum sensing-regulated genes, thereby reducing bacterial virulence both in vitro and in vivo (35,115). Recently, Chugani and Greenberg revealed an even higher level of complexity in P. aeruginosa AHL signaling, reporting a set of 37 genes whose expression was controlled by AHLs in the absence of LasR, RhlR, and QscR (34). These recent results raise questions about AHL quorum sensing regulation.…”

Section: Further Regulation Of the Ahl Systemsmentioning

confidence: 95%

The Multiple Signaling Systems Regulating Virulence in Pseudomonas aeruginosa

Nadal‐Jimenez

Koch

Thompson

et al. 2012

Microbiol Mol Biol Rev

640

626

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SUMMARY Cell-to-cell communication is a major process that allows bacteria to sense and coordinately react to the fluctuating conditions of the surrounding environment. In several pathogens, this process triggers the production of virulence factors and/or a switch in bacterial lifestyle that is a major determining factor in the outcome and severity of the infection. Understanding how bacteria control these signaling systems is crucial to the development of novel antimicrobial agents capable of reducing virulence while allowing the immune system of the host to clear bacterial infection, an approach likely to reduce the selective pressures for development of resistance. We provide here an up-to-date overview of the molecular basis and physiological implications of cell-to-cell signaling systems in Gram-negative bacteria, focusing on the well-studied bacterium Pseudomonas aeruginosa . All of the known cell-to-cell signaling systems in this bacterium are described, from the most-studied systems, i.e., N -acyl homoserine lactones (AHLs), the 4-quinolones, the global activator of antibiotic and cyanide synthesis (GAC), the cyclic di-GMP (c-di-GMP) and cyclic AMP (cAMP) systems, and the alarmones guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp), to less-well-studied signaling molecules, including diketopiperazines, fatty acids (diffusible signal factor [DSF]-like factors), pyoverdine, and pyocyanin. This overview clearly illustrates that bacterial communication is far more complex than initially thought and delivers a clear distinction between signals that are quorum sensing dependent and those relying on alternative factors for their production.

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Section: Further Regulation Of the Ahl Systemsmentioning

confidence: 95%

The Multiple Signaling Systems Regulating Virulence in Pseudomonas aeruginosa

Nadal‐Jimenez

Koch

Thompson

et al. 2012

Microbiol Mol Biol Rev

640

626

View full text Add to dashboard Cite

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“…It is possible that the double-AI synthase mutant showed a more dramatic reduction in cas gene expression compared with the single mutants and the mutant lacking both receptor genes because of compensatory effects from the orphan QS receptor QscR, which promiscuously binds AIs (30). Another possibility is that the AIs regulate cas and csy expression through a pathway that operates independently of LasR, RhlR, and QscR, as has been discovered for a few genes in P. aeruginosa PAO1 (31).…”

Section: Significancementioning

confidence: 98%

Quorum sensing controls the Pseudomonas aeruginosa CRISPR-Cas adaptive immune system

Høyland‐Kroghsbo

Paczkowski

Mukherjee

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

264

223

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CRISPR-Cas are prokaryotic adaptive immune systems that provide protection against bacteriophage (phage) and other parasites. Little is known about how CRISPR-Cas systems are regulated, preventing prediction of phage dynamics in nature and manipulation of phage resistance in clinical settings. Here, we show that the bacterium Pseudomonas aeruginosa PA14 uses the cell-cell communication process, called quorum sensing, to activate cas gene expression, to increase CRISPR-Cas targeting of foreign DNA, and to promote CRISPR adaptation, all at high cell density. This regulatory mechanism ensures maximum CRISPR-Cas function when bacterial populations are at highest risk for phage infection. We demonstrate that CRISPR-Cas activity and acquisition of resistance can be modulated by administration of proand antiquorum-sensing compounds. We propose that quorum-sensing inhibitors could be used to suppress the CRISPR-Cas adaptive immune system to enhance medical applications, including phage therapies.quorum sensing | CRISPR | immunity | phage | phage defense

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“…It is possible that CHB regulation of gene expression is not mediated by a cognate receptor. Very recently, Chugani et al (5) found that acyl-homoserine lactone (acyl-HSL) regulation in P. aeruginosa does not follow the classical QS tenet in that it is not mediated by a LuxR-type transcription factor: even after disrupting all LuxR-type receptors, there were at least 37 genes that still responded to acyl-HSL.…”

Section: Discussionmentioning

confidence: 99%

Gamma-Butyrolactone Regulatory System of Streptomyces chattanoogensis Links Nutrient Utilization, Metabolism, and Development

Shen

et al. 2011

Appl Environ Microbiol

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Gamma-butyrolactones (GBLs) produced by several Streptomyces species have been shown to serve as quorum-sensing signaling molecules for activating antibiotic production. The GBL system of Streptomyces chattanoogensis L10, a producer of antifungal agent natamycin, consists of three genes: scgA, scgX, and scgR. Both scgA and scgX contribute to GBL production, while scgR encodes a GBL receptor. ⌬scgA and ⌬scgX mutants of S. chattanoogensis behaved identically: they had a growth defect in submerged cultures and delayed or abolished the morphological differentiation and secondary metabolites production on solid medium. ScgR could bind to the promoter region of scgA and repress its transcription. Moreover, scgA seems also to be controlled by a GBL-mediated negative-feedback system. Hence, it is apparent that GBL biosynthesis is tightly controlled to ensure the correct timing for metabolic switch. An additional direct ScgR-target gene gbdA was identified by genomic SELEX and transcriptional analysis. Comparative proteomic analysis between L10 and its ⌬scgA mutant revealed that the GBL system affects the expression of more than 50 proteins, including enzymes involved in carbon uptake system, primary metabolism, and stress response, we thus conclude that scgR-scgA-scgX constitute a novel GBL regulatory system involved in nutrient utilization, triggering adaptive responses, and finally dictating the switch from primary to secondary metabolism. Quorum sensing (QS) is a cell-cell communication processin which bacteria use the production and detection of extracellular chemicals called autoinducers to monitor cell population density and synchronize community behavior through regulation of their gene expression in response to changes in cell density. Acyl homoserine lactones (AHLs) are a major class of autoinducers used by Gram-negative proteobacteria for intraspecies quorum sensing (23) and has been studied intensively over the past decade. Streptomyces, probably as well as its related genera, use ␥-butyrolactones (2,3-di-substituted-␥-butyrolactones) as autoinducers, the chemical structure of which is similar to that of AHLs except for the carbon side chain (31). In addition, other signal molecules, such as PI factor [2,3-diamino-2,3-bis(hydroxymethyl)-1,4-butanediol] and AHFCAs (2-alkyl-4-hydroxymethylfuran-3-carboxylic acids), have been described to play a similar role to that of GBLs in Streptomyces (6, 26).Streptomycetes are Gram-positive soil bacteria that undergo a developmental program that leads to sporulating aerial hyphae. They are also characterized by a complex secondary metabolism, which makes them the largest antibiotic-producing genus, producing over two-thirds of the clinically used antibiotics of natural origin. The ␥-butyrolactone (GBL) system of Streptomyces, typically consisting of a GBL synthase and a cognate receptor, is drawing more attention because of its close association with production of several antibiotics (31). Currently, there are four such systems with a known GBL and receptor, including the ...

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LuxR homolog-independent gene regulation by acyl-homoserine lactones in Pseudomonas aeruginosa

Cited by 58 publications

References 47 publications

The Multiple Signaling Systems Regulating Virulence in Pseudomonas aeruginosa

The Multiple Signaling Systems Regulating Virulence in Pseudomonas aeruginosa

Quorum sensing controls the Pseudomonas aeruginosa CRISPR-Cas adaptive immune system

Gamma-Butyrolactone Regulatory System of Streptomyces chattanoogensis Links Nutrient Utilization, Metabolism, and Development

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