scholarly journals Legionella spp. all ears? The broad occurrence of quorum sensing elements outside Legionella pneumophila

2021 ◽  
Author(s):  
Benjamin Herran ◽  
Pierre Grève ◽  
Jean-Marc Berjeaud ◽  
Joanne Bertaux ◽  
Alexandre Crépin
Keyword(s):  
Quorum Sensing ◽  
Legionella Pneumophila ◽  
Communication System ◽  
Histidine Kinase ◽  
Genomic Region ◽  
Membrane Receptors ◽  
Intracellular Pathogen ◽  
Sensing System ◽  
The World ◽  
Quorum Sensing System

Abstract Legionella spp. are ubiquitous bacteria principally found in water networks and around 20 species are implicated in Legionnaire’s disease. Among them, Legionella pneumophila is an intracellular pathogen of environmental protozoa, responsible for about 90% of cases in the world. Legionella pneumophila regulates in part its virulence by a quorum sensing system named “Legionella quorum sensing”, composed of a signal synthase LqsA, two histidine kinase membrane receptors LqsS and LqsT and a cytoplasmic receptor LqsR. To date, this communication system was only found in L. pneumophila. Here we investigated 58 Legionella genomes to determine the presence of a lqs cluster or homologous receptors using tblastn. This analysis revealed three categories of species: 19 harboured a complete lqs cluster, 20 did not possess lqsA but maintained the receptor lqsR and/or lqsS, and 19 did not have any of the lqs genes. No correlation was observed between pathogenicity and the presence of a quorum sensing system. We determined by RT-qPCR that the lqsA gene was expressed at least in four strains among different species available in our laboratory. Furthermore, we showed that the lqs genomic region was conserved even in species possessing only the receptors of the quorum sensing system, indicating an ancestral acquisition and various loss dynamics during evolution. This system could therefore function in inter-specific communication as well.

scholarly journals Quorum sensing modulates the formation of virulent Legionella persisters within infected cells

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Nicolas Personnic ◽  
Bianca Striednig ◽  
Emmanuelle Lezan ◽  
Christian Manske ◽  
Amanda Welin ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Legionella Pneumophila ◽  
Interferon Γ ◽  
Activated Macrophages ◽  
Sensing System ◽  
High Virulence ◽  
Quorum Sensing System ◽  
Infected Cells ◽  
Legionnaires Disease ◽  
Active Display

AbstractThe facultative intracellular bacterium Legionella pneumophila replicates in environmental amoebae and in lung macrophages, and causes Legionnaires’ disease. Here we show that L. pneumophila reversibly forms replicating and nonreplicating subpopulations of similar size within amoebae. The nonreplicating bacteria are viable and metabolically active, display increased antibiotic tolerance and a distinct proteome, and show high virulence as well as the capacity to form a degradation-resistant compartment. Upon infection of naïve or interferon-γ-activated macrophages, the nonreplicating subpopulation comprises ca. 10% or 50%, respectively, of the total intracellular bacteria; hence, the nonreplicating subpopulation is of similar size in amoebae and activated macrophages. The numbers of nonreplicating bacteria within amoebae are reduced in the absence of the autoinducer synthase LqsA or other components of the Lqs quorum-sensing system. Our results indicate that virulent, antibiotic-tolerant subpopulations of L. pneumophila are formed during infection of evolutionarily distant phagocytes, in a process controlled by the Lqs system.

Signal-mediated cross-talk regulates stress adaptation in Vibrio species

Microbiology ◽  
2003 ◽  
Vol 149 (7) ◽  
pp. 1923-1933 ◽  
Author(s):  
Diane McDougald ◽  
Sujatha Srinivasan ◽  
Scott A. Rice ◽  
Staffan Kjelleberg
Keyword(s):  
Quorum Sensing ◽  
Cross Talk ◽  
Communication System ◽  
Communication Systems ◽  
Vibrio Vulnificus ◽  
Homoserine Lactone ◽  
Sensing System ◽  
Sensing Systems ◽  
Quorum Sensing System ◽  
Signalling Systems

Quorum sensing systems serve as a means of ‘census taking’ of conspecific and non-conspecific bacteria in the near vicinity. The acylated homoserine lactone (AHL) quorum sensing system has been proposed to be primarily an intra-specific communication system, while the AI-2 autoinducer signalling system is proposed to be an interspecific communication system. Here it is shown that AI-2-like signalling in two marine Vibrio species, Vibrio vulnificus and ‘Vibrio angustum’ S14, induces the core response phenotypes of starvation adaptation and stress resistance, and that a signal antagonist can competitively inhibit these phenotypes. Furthermore, the signals produced by a range of Vibrio species have the ability to induce these phenotypes in V. vulnificus and ‘V. angustum’ S14, indicating that, at least in Vibrio species, AI-2-like signalling systems function as interspecies communication systems capable of ‘cross-talk’ and of regulating environmentally relevant phenotypes.

scholarly journals Acidithiobacillus Its Application in Biomining Using a Quorum Sensing Modulation Approach

2021 ◽  
Author(s):  
Juan Carlos Caicedo ◽  
Sonia Villamizar
Keyword(s):  
Quorum Sensing ◽  
Communication System ◽  
Biofilm Formation ◽  
Cell Communication ◽  
Bacterial Attachment ◽  
Sensing System ◽  
Acyl Homoserine Lactones ◽  
Quorum Sensing System ◽  
Copper Gold ◽  
Acyl Chains

A group of particular acidophiles microorganisms (bacteria and archaea) known as chemolithoautotrophs are capable of using minerals as fuel. Its oxidation generates electrons to obtain energy and carbon that is obtained by fixing CO2 from the air. During this aerobic mineral oxidation, metals are solubilized or biodegraded. Metal bioleaching usually is used in biomining and urban biomining approaches to recovery metals such as copper, gold and zinc. Several species of bacterial genus Acidithiobacillus display a great bioleaching activity. Bacterial attachment and biofilm formation are the initial requirements to begin a successful bioleaching process. Biofilm formation in Acidithiobacillus bacteria is strongly regulated by cell to cell communication system called Quorum Sensing. The goal of this chapter is to review the Quorum Sensing system mediated by the autoinducer N-acyl- homoserine-lactones in the Bacterium Acidiothiobacillus ferroxidans, in order to enhance and to boost the bioleaching technologies based in the use of this bacterium. The main applications of the cell-to-cell communication system concepts in A. ferrooxidans are reviewed in this chapter. It is that the addition of synthetic autoinducers molecules, which act as agonist of quorum sensing system, especially those with long acyl chains, both as single molecules (C12-AHL, 3-hydroxy-C12-AHL, C14-AHL, and 3-hydroxy-C14-AHL) or as a mixture (C14-AHL/3- hydroxy-C14-AHL/3-oxo-C14-AHL) increased the adhesion to sulfur and pyrite and enhance the metal bioleaching in urban biomining approaches.

#99: Streptococcus pyogenes Utilizes the Peptide-Based Rgg 2/3 Quorum Sensing System During Oropharyngeal Colonization

2021 ◽  
Vol 10 (Supplement_1) ◽  
pp. S10-S10
Author(s):  
Artemis Gogos ◽  
Michael J Federle
Keyword(s):  
Quorum Sensing ◽  
Streptococcus Pyogenes ◽  
Lymphoid Tissue ◽  
Transcriptional Activator ◽  
Rt Pcr ◽  
Sensing System ◽  
Bacterial Rna ◽  
Quorum Sensing System ◽  
Luciferase Reporters

Abstract Background Streptococcus pyogenes is a human-restricted pathogen most often found in the human nasopharynx. Multiple bacterial factors have been found to contribute to persistent colonization of this niche, and many of these factors are important in mucosal immunity and vaccine development. In this work, we infected mice intranasally with transcriptional regulator mutants of the Rgg2/3 quorum sensing (QS) system—a peptide-based signaling system conserved in all sequenced isolates of S. pyogenes. Methods Three-week-old CD1 mice were intranasally infected with ~107 CFU of S. pyogenes strain MGAS315. Calcium alginate throat swabs were used to monitor nasopharyngeal colonization by the bacteria over time. Luciferase reporters used alongside an IVIS camera were able to show quorum sensing activity levels after inoculation into the mouse nose. Bacterial RNA was isolated from the throat of the mice and quantitative RT–PCR was performed on the samples to corroborate the luciferase reporter data. The nasal-associated lymphoid tissue (NALT) was excised and its supernatants were subjected to 32-plex murine cytokine and chemokine analysis (Millipore). Results Deletion of the QS system’s transcriptional activator (Δrgg2) dramatically diminished the percentage of colonized mice. Deletion of the transcriptional repressor (Δrgg3) increased the percentage of colonized mice compared with wild type. Stimulation of the QS system using synthetic pheromones prior to inoculation did not significantly increase the percentage of animals colonized, indicating that activity of the QS system is responsive to conditions of the host nasopharynx. Mice inoculated with QS-dependent luciferase reporters were subjected to in vivo imaging and showed activation within 1 hour. Bacterial RNA extracted directly from oropharyngeal swabs and evaluated by quantitative RT–PCR subsequently confirmed QS upregulation within 1 hour of inoculation. In the nasal-associated lymphoid tissue (NALT), a muted inflammatory response to the Δrgg2 bacteria suggests that their rapid elimination fails to elicit the previously characterized response to intranasal inoculation of GAS. Conclusions Deletion of the Rgg2 transcriptional activator of the Rgg 2/3 quorum sensing system eliminates colonization of the murine nasopharynx and changes the transcriptional profile of the bacteria in this niche. An existing small-molecule inhibitor of the Rgg2/3 system was unable to inhibit QS activation in vivo, likely due to the suboptimal achievable doses; however, results of our study indicate inhibition of QS may diminish the oropharyngeal colonization of S. pyogenes and argue for further development.

Investigating the Quorum Sensing System in Halophilic Bacteria

2015 ◽  
pp. 189-207 ◽  
Author(s):  
Tommonaro Giuseppina ◽  
Abbamondi Gennaro Roberto ◽  
Toksoy Oner Ebru ◽  
Nicolaus Barbara
Keyword(s):  
Quorum Sensing ◽  
Halophilic Bacteria ◽  
Sensing System ◽  
Quorum Sensing System

scholarly journals Inhibition of exoprotease production in Aeromonas hydrophila by rhizome extract of temu lawak (Curcuma xanthorrhiza (Roxb.)

2006 ◽  
Vol 4 (2) ◽  
pp. 45-54
Author(s):  
UMI LESTARI ◽  
ARTINI PANGASTUTI ◽  
ARI SUSILOWATI
Keyword(s):  
Quorum Sensing ◽  
Ethyl Acetate ◽  
Aeromonas Hydrophila ◽  
Ethanol Extract ◽  
Homoserine Lactone ◽  
Sensing System ◽  
Development Of Resistance ◽  
Quorum Sensing System ◽  
Assay Result ◽  
Curcuma Xanthorrhiza

Conventional treatment of infectious diseases is based on compounds that kill or inhibit the growth of bacteria. A major concern with this approach is the frequent development of resistance to antimicrobial compounds. The discovery of communication (quorum sensing system) regulating bacterial virulence opens up ways to control certain bacterial infectious without interfering the growth. The fish pathogen Aeromonas hydrophila produces quorum sensing signal, NButanoyl-L-Homoserine Lactone (C4-HSL). C4-HSL regulates exoprotease synthesis, a virulence factor of A. hydrophila. Expression of exoprotease can be blocked by using quorum sensing inhibitor. The purpose of this study was to investigate the inhibiting effect of Curcuma xanthorrhiza (Roxb.) extract to exoprotease production of A. hydrophila. Extraction was conducted by using n-hexane, ethyl acetate and ethanol. The qualitative exoprotease assay result showed that n-hexane extract of C. xanthorrhiza had not effect on growth and exoprotease production of A. hydrophila. Meanwhile, 4% of ethyl acetate and ethanol extract of C. xanthorrhiza can inhibit exoprotease production without affecting A. hydrophilla growth. The quantitative exoprotease assay result showed that 4% of ethyl acetate and ethanol extract can inhibit the exoprotease production by 93,9% and 95,6%. The growth of A. hydrophila was not affected by this extract.

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