scholarly journals Identification of Quorum-Sensing-Regulated Genes of Burkholderia cepacia

2003 ◽  
Vol 185 (21) ◽  
pp. 6456-6462 ◽  
Author(s):  
Claudio Aguilar ◽  
Arianna Friscina ◽  
Giulia Devescovi ◽  
Milan Kojic ◽  
Vittorio Venturi
Keyword(s):  
Quorum Sensing ◽  
Burkholderia Cepacia ◽  
Regulatory System ◽  
Extracellular Proteins ◽  
Gram Negative Bacteria ◽  
Gene Promoters ◽  
Regulation Of Expression ◽  
Putative Gene ◽  
Homoserine Lactones ◽  
Global Regulatory System

ABSTRACT Quorum sensing is a regulatory mechanism (operating in response to cell density) which in gram-negative bacteria usually involves the production of N-acyl homoserine lactones (HSL). Quorum sensing in Burkholderia cepacia has been associated with the regulation of expression of extracellular proteins and siderophores and also with the regulation of swarming and biofilm formation. In the present study, several quorum-sensing-controlled gene promoters of B. cepacia ATCC 25416 were identified and characterized. A total of 28 putative gene promoters show CepR-C8-HSL-dependent expression, suggesting that quorum sensing in B. cepacia is a global regulatory system.

scholarly journals Distribution of Quorum-Sensing Genes in the Burkholderia cepacia Complex

2001 ◽  
Vol 69 (7) ◽  
pp. 4661-4666 ◽  
Author(s):  
E. Lutter ◽  
S. Lewenza ◽  
J. J. Dennis ◽  
M. B. Visser ◽  
P. A. Sokol
Keyword(s):  
Quorum Sensing ◽  
Burkholderia Cepacia ◽  
Homoserine Lactone ◽  
Burkholderia Cepacia Complex ◽  
Homoserine Lactones

ABSTRACT The distribution of quorum-sensing genes among strains from seven genomovars of the Burkholderia cepaciacomplex was examined by PCR. cepR and cepI were amplified from B. cepacia genomovars I and III, B. stabilis, and B. vietnamiensis. cepR was also amplified from B. multivorans and B. cepacia genomovar VI. bviIR were amplified from B. vietnamiensis. All genomovars producedN-octanoyl-l-homoserine lactone andN-hexanoyl-l-homoserine lactone.B. vietnamiensis and B. cepacia genomovar VII produced additional N-acyl-l-homoserine lactones.

scholarly journals Burkholderia pseudomallei, B. thailandensis, and B. ambifaria Produce 4-Hydroxy-2-Alkylquinoline Analogues with a Methyl Group at the 3 Position That Is Required for Quorum-Sensing Regulation

2008 ◽  
Vol 190 (15) ◽  
pp. 5339-5352 ◽  
Author(s):  
Ludovic Vial ◽  
François Lépine ◽  
Sylvain Milot ◽  
Marie-Christine Groleau ◽  
Valérie Dekimpe ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Burkholderia Cepacia ◽  
Burkholderia Pseudomallei ◽  
Alkyl Chain ◽  
Quinoline Ring ◽  
Liquid Chromatography Mass Spectrometry ◽  
Methyl Group ◽  
Homoserine Lactones ◽  
Acyl Homoserine Lactones ◽  
Oxide Group

ABSTRACT 4-Hydroxy-2-alkylquinolines (HAQs), especially 3,4-dihydroxy-2-heptylquinoline (Pseudomonas quinolone signal) and its precursor, 4-hydroxy-2-heptylquinoline, are attracting much attention, mainly because of their role as signaling molecules in Pseudomonas aeruginosa. The pqsABCDE operon is centrally involved in their biosynthesis. The presence of a homologous operon in Burkholderia pseudomallei and B. thailandensis was recently reported. Thus, we have investigated the abilities of 11 Burkholderia species to produce HAQ-like molecules by liquid chromatography/mass spectrometry. We have identified 29 different HAQ derivatives produced by the only three Burkholderia species where a pqsABCDE homologue was found among available sequenced Burkholderia species genomes, including B. ambifaria, a member of the Burkholderia cepacia complex. In contrast with those of P. aeruginosa, Burkholderia HAQs typically bear a methyl group, hence their designation as 4-hydroxy-3-methyl-2-alkylquinolines (HMAQs). We identified three families of HMAQs with a saturated or unsaturated alkyl chain at the 2′ position, in contrast with the 1′ position of P. aeruginosa, including one with an N-oxide group. Furthermore, the operon in these species contains two more genes downstream of the pqsE homologue, resulting in the hmqABCDEFG operon. While the inactivation of hmqA inhibits the production of HMAQs, the methylation of the quinoline ring requires a putative methyltransferase encoded by hmqG. Interestingly, hmqA or hmqG mutations increase the production of acyl homoserine lactones and, consequently, phenotypes under the control of quorum sensing in B. ambifaria: antifungal activity, siderophore production, and proteolytic activity. These results indicate that only HAQs bearing a methyl group (HMAQs) are involved in quorum-sensing regulation.

scholarly journals Mutations of the Quorum Sensing-Dependent Regulator VjbR Lead to Drastic Surface Modifications in Brucella melitensis

2007 ◽  
Vol 189 (16) ◽  
pp. 6035-6047 ◽  
Author(s):  
Sophie Uzureau ◽  
Marie Godefroid ◽  
Chantal Deschamps ◽  
Julien Lemaire ◽  
Xavier De Bolle ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Brucella Melitensis ◽  
Outer Membrane Proteins ◽  
Regulatory System ◽  
Fine Tuning ◽  
Altered Expression ◽  
Homoserine Lactones ◽  
Type Iv ◽  
Cell Surface Structures

ABSTRACT Successful establishment of infection by bacterial pathogens requires fine-tuning of virulence-related genes. Quorum sensing (QS) is a global regulation process based on the synthesis of, detection of, and response to small diffusible molecules, called N-acyl-homoserine lactones (AHL), in gram-negative bacteria. In numerous species, QS has been shown to regulate genes involved in the establishment of pathogenic interactions with the host. Brucella melitensis produces N-dodecanoyl homoserine lactones (C12-HSL), which down regulate the expression of flagellar genes and of the virB operon (encoding a type IV secretion system), both of which encode surface virulence factors. A QS-related regulator, called VjbR, was identified as a transcriptional activator of these genes. We hypothesized that VjbR mediates the C12-HSL effects described above. vjbR alleles mutated in the region coding for the AHL binding domain were constructed to test this hypothesis. These alleles expressed in trans in a ΔvjbR background behave as constitutive regulators both in vitro and in a cellular model of infection. Interestingly, the resulting B. melitensis strains, unable to respond to AHLs, aggregate spontaneously in liquid culture. Preliminary characterization of these strains showed altered expression of some outer membrane proteins and overproduction of a matrix-forming exopolysaccharide, suggesting for the first time that B. melitensis could form biofilms. Together, these results indicate that QS through VjbR is a major regulatory system of important cell surface structures of Brucella and as such plays a key role in host-pathogen interactions.

scholarly journals Biofilms on Indwelling Urethral Catheters Produce Quorum-Sensing Signal Molecules In Situ and In Vitro

1998 ◽  
Vol 64 (9) ◽  
pp. 3486-3490 ◽  
Author(s):  
David J. Stickler ◽  
Nicola S. Morris ◽  
Robert J. C. McLean ◽  
Clay Fuqua
Keyword(s):  
Quorum Sensing ◽  
Signal Molecules ◽  
Gram Negative Bacteria ◽  
Feeding Assay ◽  
Gram Negative ◽  
Homoserine Lactones ◽  
Acylated Homoserine Lactones

ABSTRACT Acylated homoserine lactones (AHLs) are chemical signals that mediate population density-dependent (quorum-sensing) gene expression in numerous gram-negative bacteria. In this study, gram-negative bacilli isolated from catheters were screened for AHL production by a cross-feeding assay utilizing an AHL-responsive Agrobacterium tumefaciens reporter strain. Positive reactions were obtained from 14 isolates of Pseudomonas aeruginosa; negative or weakly positive reactions were recorded for isolates of five other species. P. aeruginosa biofilms were then produced on catheters in a physical model of the bladder. Sections of colonized all-silicone catheters gave positive reactions for the quorum-sensing signal molecules as did sections that had been cleaned of biofilm and autoclaved. Control sections of unused catheters were negative in the tests. Sections from four of nine catheters that had been freshly removed from patients gave positive reactions for AHLs. Cleaned autoclaved sections of three of these catheters also gave strongly positive reactions for AHLs. These results demonstrate that AHLs are produced by biofilms as they develop on the catheters both in vitro in the model and in vivo in the patient’s bladder. They represent the first demonstration of AHL production by biofilms in a clinical setting.

N-Acylhomoserine lactone quorum-sensing signalling in antagonistic phenazine-producing Pseudomonas isolates from the red cocoyam rhizosphere

Microbiology ◽  
2011 ◽  
Vol 157 (2) ◽  
pp. 459-472 ◽  
Author(s):  
K. De Maeyer ◽  
J. D'aes ◽  
G. K. H. Hua ◽  
M. Perneel ◽  
L. Vanhaecke ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Regulatory System ◽  
Homoserine Lactone ◽  
Antagonistic Activity ◽  
Signal Molecules ◽  
Pseudomonas Chlororaphis ◽  
Homoserine Lactones ◽  
Acylhomoserine Lactone ◽  
Phenazine Production ◽  
Phenazine Antibiotics

Forty fluorescent Pseudomonas strains isolated from white and red cocoyam roots were tested for their ability to synthesize N-acyl-l-homoserine lactones (acyl-HSLs). Remarkably, only isolates from the red cocoyam rhizosphere that were antagonistic against the cocoyam root rot pathogen Pythium myriotylum and synthesized phenazine antibiotics produced acyl-HSLs. This supports the assumption that acyl-HSL production is related to the antagonistic activity of the strains. After detection, the signal molecules were identified through TLC-overlay and liquid chromatography-multiple MS (LC-MS/MS) analysis. In our representative strain, Pseudomonas CMR12a, production of the signal molecules could be assigned to two quorum-sensing (QS) systems. The first one is the QS system for phenazine production, PhzI/PhzR, which seemed to be well conserved, since it was genetically organized in the same way as in the well-described phenazine-producing Pseudomonas strains Pseudomonas fluorescens 2-79, Pseudomonas chlororaphis PCL1391 and Pseudomonas aureofaciens 30-84. The newly characterized genes cmrI and cmrR make up the second QS system of CMR12a, under the control of the uncommon N-3-hydroxy-dodecanoyl-homoserine lactone (3-OH-C12-HSL) and with low similarity to other Pseudomonas QS systems. No clear function could yet be assigned to the CmrI/CmrR system, although it contributes to the biocontrol capability of CMR12a. Both the PhzI/PhzR and CmrI/CmrR systems are controlled by the GacS/GacA two-component regulatory system.

scholarly journals Synthesis of N-Acyl Homoserine Lactone Analogues Reveals Strong Activators of SdiA, the Salmonella enterica Serovar Typhimurium LuxR Homologue

2006 ◽  
Vol 73 (2) ◽  
pp. 535-544 ◽  
Author(s):  
Joost C. A. Janssens ◽  
Kristine Metzger ◽  
Ruth Daniels ◽  
Dave Ptacek ◽  
Tine Verhoeven ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Vibrio Fischeri ◽  
Acyl Chain ◽  
Homoserine Lactone ◽  
Gram Negative Bacteria ◽  
Ligand Interaction ◽  
Homoserine Lactones ◽  
Serovar Typhimurium

ABSTRACT N-Acyl homoserine lactones (AHLs) are molecules that are synthesized and detected by many gram-negative bacteria to monitor the population density, a phenomenon known as quorum sensing. Salmonella enterica serovar Typhimurium is an exceptional species since it does not synthesize its own AHLs, while it does encode a LuxR homologue, SdiA, which enables this bacterium to detect AHLs that are produced by other species. To obtain more information about the specificity of the ligand binding by SdiA, we synthesized and screened a limited library of AHL analogues. We identified two classes of analogues that are strong activators of SdiA: the N-(3-oxo-acyl)-homocysteine thiolactones (3O-AHTLs) and the N-(3-oxo-acyl)-trans-2-aminocyclohexanols. To our knowledge, this is the first report of compounds (the 3O-AHTLs) that are able to activate a LuxR homologue at concentrations that are lower than the concentrations of the most active AHLs. SdiA responds with greatest sensitivity to AHTLs that have a keto modification at the third carbon atom and an acyl chain that is seven or eight carbon atoms long. The N-(3-oxo-acyl)-trans-2-aminocyclohexanols were found to be less sensitive to deactivation by lactonase and alkaline pH than the 3O-AHTLs and the AHLs are. We also examined the activity of our library with LuxR of Vibrio fischeri and identified three new inhibitors of LuxR. Finally, we performed preliminary binding experiments which suggested that SdiA binds its activators reversibly. These results increase our understanding of the specificity of the SdiA-ligand interaction, which could have uses in the development of anti-quorum-sensing-based antimicrobials.

scholarly journals Detection of Quorum Sensing Signal Molecules, Particularly N-Acyl Homoserine Lactones, 2-Alky-4-Quinolones, and Diketopiperazines, in Gram-Negative Bacteria Isolated From Insect Vector of Leishmaniasis

2021 ◽  
Vol 2 ◽  
Author(s):  
Rafael Jose Vivero-Gomez ◽  
Gustavo Bedoya Mesa ◽  
Jorge Higuita-Castro ◽  
Sara M. Robledo ◽  
Claudia X. Moreno-Herrera ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Enterobacter Aerogenes ◽  
Enterobacter Cloacae ◽  
Homoserine Lactone ◽  
Migration Pattern ◽  
Insect Vector ◽  
Gram Negative Bacteria ◽  
Homoserine Lactones ◽  
Sensing System ◽  
Intracellular Content

Gram-negative bacteria are known to use a quorum sensing system to facilitate and stimulate cell to cell communication, mediated via regulation of specific genes. This system is further involved in the modulation of cell density and metabolic and physiological processes that putatively either affect the survival of insect vectors or the establishment of pathogens transmitted by them. The process of quorum sensing generally involves N-acyl homoserine lactones and 2-alkyl-4-quinolones signaling molecules. The present study aimed to detect and identify quorum sensing signaling molecules of AHLs and AHQs type that are secreted by intestinal bacteria, and link their production to their extracellular milieu and intracellular content. Isolates for assessment were obtained from the intestinal tract of Pintomyia evansi (Leishmania insect vector). AHLs and AHQs molecules were detected using chromatography (TLC) assays, with the aid of specific and sensitive biosensors. For identity confirmation, ultra-high-performance liquid chromatography coupled with mass spectrometry was used. TLC assays detected quorum sensing molecules (QSM) in the supernatant of the bacterial isolates and intracellular content. Interestingly, Pseudomonas otitidis, Enterobacter aerogenes, Enterobacter cloacae, and Pantoea ananatis isolates showed a migration pattern similar to the synthetic molecule 3-oxo-C6-HSL (OHHL), which was used as a control. Enterobacter cancerogenus secreted C6-HSL, a related molecules to N-hexanoyl homoserine lactone (HHL), while Acinetobacter gyllenbergii exhibited a migration pattern similar to 2-heptyl-4-quinolone (HHQ) molecules. In comparison to this, 3-oxo-C12-HSL (OdDHL) type molecules were produced by Lysobacter soli, Pseudomonas putida, A. gyllenbergii, Acinetobacter calcoaceticus, and Pseudomonas aeruginosa, while Enterobacter cloacae produced molecules similar to 2-heptyl-3-hydroxy-4-quinolone (PQS). For Pseudomonas putida, Enterobacter aerogenes, P. ananatis, and Pseudomonas otitidis extracts, peak chromatograms with distinct retention times and areas, consistent with the molecules described in case of TLC, were obtained using HPLC. Importantly, P. ananatis produced a greater variety of high QSM concentration, and thus served as a reference for confirmation and identification by UHPLC-MRM-MS/MS. The molecules that were identified included N-hexanoyl-L-homoserine lactone [HHL, C10H18NO3, (M + H)], N-(3-oxohexanoyl)-L-homoserine lactone [OHHL, C10H16NO4, (M + H)], N-(3-oxododecanoyl)-L-homoserine lactone [OdDHL, C16H28NO4, (M + H)], and 2-heptyl-3-hydroxy-4(1H)-quinolone [PQS, C16H22NO2, (M + H)]. Besides this, the detection of diketopiperazines, namely L-Pro-L-Tyr and ΔAla-L-Val cyclopeptides was reported for P. ananatis. These molecules might be potentially associated with the regulation of QSM system, and might represent another small molecule-mediated bacterial sensing system. This study presents the first report regarding the detection and identification of QSM and diketopiperazines in the gut sand fly bacteria. The possible effect of QSM on the establishment of Leishmania must be explored to determine its role in the modulation of intestinal microbiome and the life cycle of Pi. evansi.

scholarly journals Quorum Sensing Inhibitory Potential and Molecular Docking Studies of Phyllanthus Emblica Phytochemicals Against Pseudomonas Aeruginosae

2021 ◽  
Author(s):  
Sharmila Baburam ◽  
Srinivasan Ramasamy ◽  
Gnanendra Shanmugam ◽  
Maghimaa Mathanmohun
Keyword(s):  
Quorum Sensing ◽  
Docking Studies ◽  
Chromobacterium Violaceum ◽  
Gram Negative Bacteria ◽  
Phyllanthus Emblica ◽  
Signaling System ◽  
Homoserine Lactones ◽  
Bio Monitoring ◽  
Inhibitory Potential ◽  
Anti Fungal

Abstract Phyllanthus emblica a traditional medicinal plant that is endowed with curative properties including anti-bacterial, anti-fungal, anti-viral, and analgesic properties. Bacteria make use of cell–cell signaling system known as Quorum sensing (QS) and respond to their own population. In most gram-negative bacteria, the transcriptional regulators belonging to the Lux R protein play a crucial role in the QS mechanism by detecting the presence of signaling molecules known as N-acyl homoserine lactones (AHLs). In this present work, the anti-quorum sensing activity of Phyllanthus emblica was evaluated against Pseudomonas aeruginosa. Anti-quorum sensing efficacy of Phyllanthus emblica was estimated with reference to QS Bio-monitoring strain Chromobacterium violaceum. The binding efficacy of the phytochemicals of Phyllanthus emblica against CviR Protein from Chromobacterium violaceum and LasR Protein from Phyllanthus emblica were studied.

scholarly journals Evidence of Quorum Sensing in Cyanobacteria by Homoserine Lactones: The Origin of Blooms

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1831
Author(s):  
Natalia Herrera ◽  
Fernando Echeverri
Keyword(s):  
Cell Proliferation ◽  
Quorum Sensing ◽  
Microcystis Aeruginosa ◽  
Industrial Effluents ◽  
Cyanobacterial Blooms ◽  
Cylindrospermopsis Raciborskii ◽  
Bacterial Communication ◽  
Homoserine Lactones ◽  
Exogenous Compounds ◽  
Almost All

Although several theories have been postulated to explain cyanobacterial blooms, their biochemical origin has not yet been found. In this work, we explore the existence of bacterial communication, called quorum sensing, in Microcystis aeruginosa and Cylindrospermopsis raciborskii. Thus, the application of several known acylhomoserine lactones to cultures of both cyanobacteria causes profound metabolic. At 72 h post-application, some of them produced substantial increases in cell proliferation, while others were inhibitors. There was a correlation with colony-forming activity for most of them. According to ELISA analysis, the microcystin levels were increased with some lactones. However, there was a clear difference between M. aeruginosa and C. raciborskii culture since, in the first one, there was an inducing effect on cell proliferation, while in C. raciborskii, the effects were minor. Besides, there were compound inhibitors and inducers of microcystins production in M. aeruginosa, but almost all compounds were only inducers of saxitoxin production in C. raciborskii. Moreover, each lactone appears to be involved in a specific quorum sensing process. From these results, the formation of cyanobacterial blooms in dams and reservoirs could be explained since lactones may come from cyanobacteria and other sources as bacterial microflora-associated or exogenous compounds structurally unrelated to lactones, such as drugs, industrial effluents, and agrochemicals.

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