scholarly journals Loss of Motility as a Non-Lethal Mechanism for Intercolony Inhibition (“Sibling Rivalry”) in Marinobacter

2021 ◽  
Vol 9 (1) ◽  
pp. 103
Author(s):  
Ricardo Cruz-López ◽  
Piotr Kolesinski ◽  
Frederik De Boever ◽  
David H. Green ◽  
Mary W. Carrano ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Chemical Communication ◽  
Ecological Niche ◽  
Inhibition Zone ◽  
Marine Snow ◽  
Niche Space ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
Wide Range ◽  
Quorum Sensing System

Bacteria from the genus Marinobacter are ubiquitous throughout the worlds’ oceans as “opportunitrophs” capable of surviving a wide range of conditions, including colonization of surfaces of marine snow and algae. To prevent too many bacteria from occupying this ecological niche simultaneously, some sort of population dependent control must be operative. Here, we show that while Marinobacter do not produce or utilize an acylhomoserine lactone (AHL)-based quorum sensing system, “sibling” colonies of many species of Marinobacter exhibit a form of non-lethal chemical communication that prevents colonies from overrunning each other’s niche space. Evidence suggests that this inhibition is the result of a loss in motility for cells at the colony interfaces. Although not the signal itself, we have identified a protein, glycerophosphoryl diester phosphodiesterase, that is enriched in the inhibition zone between the spreading colonies that may be part of the overall response.

scholarly journals The LuxM Homologue VanM from Vibrio anguillarumDirects the Synthesis of N-(3-Hydroxyhexanoyl)homoserine Lactone and N-Hexanoylhomoserine Lactone

2001 ◽  
Vol 183 (12) ◽  
pp. 3537-3547 ◽  
Author(s):  
Debra L. Milton ◽  
Victoria J. Chalker ◽  
David Kirke ◽  
Andrea Hardman ◽  
Miguel Cámara ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Vibrio Anguillarum ◽  
Homoserine Lactone ◽  
Regulatory Elements ◽  
Sequencing Error ◽  
Infection Model ◽  
Reading Frame ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
Quorum Sensing System

ABSTRACT Vibrio anguillarum, which causes terminal hemorrhagic septicemia in fish, was previously shown to possess a LuxRI-type quorum-sensing system (vanRI) and to produceN-(3-oxodecanoyl)homoserine lactone (3-oxo-C10-HSL). However, a vanI null mutant still activatedN-acylhomoserine lactone (AHL) biosensors, indicating the presence of an additional quorum-sensing circuit in V. anguillarum. In this study, we have characterized this second system. Using high-pressure liquid chromatography in conjunction with mass spectrometry and chemical analysis, we identified two additional AHLs as N-hexanoylhomoserine lactone (C6-HSL) andN-(3-hydroxyhexanoyl)homoserine lactone (3-hydroxy-C6-HSL). Quantification of each AHL present in stationary-phase V. anguillarum spent culture supernatants indicated that 3-oxo-C10-HSL, 3-hydroxy-C6-HSL, and C6-HSL are present at approximately 8.5, 9.5, and 0.3 nM, respectively. Furthermore,vanM, the gene responsible for the synthesis of these AHLs, was characterized and shown to be homologous to the luxLand luxM genes, which are required for the production ofN-(3-hydroxybutanoyl)homoserine lactone in Vibrio harveyi. However, resequencing of the V. harveyi luxL/luxM junction revealed a sequencing error present in the published sequence, which when corrected resulted in a single open reading frame (termed luxM). Downstream ofvanM, we identified a homologue of luxN(vanN) that encodes a hybrid sensor kinase which forms part of a phosphorelay cascade involved in the regulation of bioluminescence in V. harveyi. A mutation in vanM abolished the production of C6-HSL and 3-hydroxy-C6-HSL. In addition, production of 3-oxo-C10-HSL was abolished in the vanM mutant, suggesting that 3-hydroxy-C6-HSL and C6-HSL regulate the production of 3-oxo-C10-HSL via vanRI. However, a vanN mutant displayed a wild-type AHL profile. Neither mutation affected either the production of proteases or virulence in a fish infection model. These data indicate that V. anguillarum possesses a hierarchical quorum sensing system consisting of regulatory elements homologous to those found in both V. fischeri (the LuxRI homologues VanRI) and V. harveyi (the LuxMN homologues, VanMN).

scholarly journals The Plant Pathogen Pantoea ananatis Produces N-Acylhomoserine Lactone and Causes Center Rot Disease of Onion by Quorum Sensing

2007 ◽  
Vol 189 (22) ◽  
pp. 8333-8338 ◽  
Author(s):  
Tomohiro Morohoshi ◽  
Yuta Nakamura ◽  
Go Yamazaki ◽  
Akio Ishida ◽  
Norihiro Kato ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Receptor Gene ◽  
Homoserine Lactone ◽  
Pantoea Ananatis ◽  
Signal Molecule ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Rot Disease

ABSTRACT A number of gram-negative bacteria have a quorum-sensing system and produce N-acyl-l-homoserine lactone (AHL) that they use them as a quorum-sensing signal molecule. Pantoea ananatis is reported as a common colonist of wheat heads at ripening and causes center rot of onion. In this study, we demonstrated that P. ananatis SK-1 produced two AHLs, N-hexanoyl-l-homoserine lactone (C6-HSL) and N-(3-oxohexanoyl)-l-homoserine lactone (3-oxo-C6-HSL). We cloned the AHL-synthase gene (eanI) and AHL-receptor gene (eanR) and revealed that the deduced amino acid sequence of EanI/EanR showed high identity to those of EsaI/EsaR from P. stewartii. EanR repressed the ean box sequence and the addition of AHLs resulted in derepression of ean box. Inactivation of the chromosomal eanI gene in SK-1 caused disruption of exopolysaccharide (EPS) biosynthesis, biofilm formation, and infection of onion leaves, which were recovered by adding exogenous 3-oxo-C6-HSL. These results demonstrated that the quorum-sensing system involved the biosynthesis of EPS, biofilm formation, and infection of onion leaves in P. ananatis SK-1.

scholarly journals Evaluation of the Antibacterial and Investigation of the Molecular Docking of New Derivatives of 1, 3, 4-Oxadiazole as Inhibitors of Quorum Sensing System in the Human Pathogen Pseudomonas Aeruginosa

2021 ◽  
Vol 8 (1) ◽  
pp. 27-33
Author(s):  
Sepideh Ghameshlouei ◽  
Nakisa Zarrabi Ahrabi ◽  
Ali Souldozi ◽  
Yasin SarveAhrabi
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Molecular Docking ◽  
Quorum Sensing ◽  
Regulatory Protein ◽  
Inhibitory Effect ◽  
Chemical Structures ◽  
Sensing System ◽  
Wide Range ◽  
Quorum Sensing System ◽  
Derivatives Of

Background: Oxadiazoles are a group of anti-inflammatory compounds that have a wide range of activity due to their higher efficacy. Pseudomonas aeruginosa is an opportunistic pathogen and a major pathogen of nosocomial infections. This study aimed to evaluate the antibacterial and investigation of the molecular docking of new derivatives of 1, 3, 4-oxadiazole against P. aeruginosa, in vitro & in silico. Materials and Methods: Four new derivatives were synthesized and added to our previous synthetic derivatives of 1, 3, 4-oxadiazole. The antibacterial activity of all derivatives was measured based on three standard species of P. aeruginosa using inhibition zone (IZ) and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. Then, employing the computational design of the drug by the molecular docking method, the inhibitory effect of synthetic compounds on the LasR regulatory protein of P. aeruginosa quorum sensing system was investigated, which plays an important role in regulating the expression of pathogenic genes in bacteria. Results: The chemical structures of new compounds were characterized by IR spectra and 1H-NMR. A variety of inhibitory effects were observed by the synthesized compounds – compound 4d and 4g, in particular. Also, the inhibitory effect of these two compounds on the LasR regulatory protein under the control of the quorum sensing system in P. aeruginosa was demonstrated by molecular docking. Conclusions: The results of this study showed that the two compounds containing the functional group of naphthalene and fluorophenyl have a significant effect on the inhibition of P. aeruginosa, as well as on the LasR protein of this bacterium.

scholarly journals N-Octanoylhomoserine lactone signalling mediated by the BpsI–BpsR quorum sensing system plays a major role in biofilm formation of Burkholderia pseudomallei

Microbiology ◽  
2011 ◽  
Vol 157 (4) ◽  
pp. 1176-1186 ◽  
Author(s):  
Akshamal Mihiranga Gamage ◽  
Guanghou Shui ◽  
Markus R. Wenk ◽  
Kim Lee Chua
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Burkholderia Pseudomallei ◽  
Homoserine Lactone ◽  
Tandem Ms ◽  
Wild Type ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
Sensing Systems ◽  
Quorum Sensing System

The genome of Burkholderia pseudomallei encodes three acylhomoserine lactone (AHL) quorum sensing systems, each comprising an AHL synthase and a signal receptor/regulator. The BpsI–BpsR system produces N-octanoylhomoserine lactone (C8HL) and is positively auto-regulated by its AHL product. The products of the remaining two systems have not been identified. In this study, tandem MS was used to identify and quantify the AHL species produced by three clinical B. pseudomallei isolates – KHW, K96243 and H11 – three isogenic KHW mutants that each contain a null mutation in an AHL synthase gene, and recombinant Escherichia coli heterologously expressing each of the three B. pseudomallei AHL synthase genes. BpsI synthesized predominantly C8HL, which accounted for more than 95 % of the extracellular AHLs produced in stationary-phase KHW cultures. The major products of BpsI2 and BpsI3 were N-(3-hydroxy-octanoyl)homoserine lactone (OHC8HL) and N-(3-hydroxy-decanoyl)homoserine lactone, respectively, and their corresponding transcriptional regulators, BpsR2 and BpsR3, were capable of driving reporter gene expression in the presence of these cognate lactones. Formation of biofilm by B. pseudomallei KHW was severely impaired in mutants lacking either BpsI or BpsR but could be restored to near wild-type levels by exogenous C8HL. BpsI2 was not required, and BpsI3 was partially required for biofilm formation. Unlike the bpsI mutant, biofilm formation in the bpsI3 mutant could not be restored to wild-type levels in the presence of OHC8HL, the product of BpsI3. C8HL and OHC8HL had opposite effects on biofilm formation; exogenous C8HL enhanced biofilm formation in both the bpsI3 mutant and wild-type KHW while exogenous OHC8HL suppressed the formation of biofilm in the same strains. We propose that exogenous OHC8HL antagonizes biofilm formation in B. pseudomallei, possibly by competing with endogenous C8HL for binding to BpsR.

scholarly journals The PmlI-PmlR Quorum-Sensing System in Burkholderia pseudomallei Plays a Key Role in Virulence and Modulates Production of the MprA Protease

2004 ◽  
Vol 186 (8) ◽  
pp. 2288-2294 ◽  
Author(s):  
E. Valade ◽  
F. M. Thibault ◽  
Y. P. Gauthier ◽  
M. Palencia ◽  
M. Y. Popoff ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Stationary Phase ◽  
Cell Density ◽  
Burkholderia Pseudomallei ◽  
Wild Type ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
Wild Type Phenotype ◽  
Significant Difference ◽  
Quorum Sensing System

ABSTRACT Burkholderia pseudomallei is the causative agent of melioidosis, an often fatal infection of humans and animals. The virulence of this pathogen is thought to depend on a number of secreted proteins, including the MprA metalloprotease. We observed that MprA is produced upon entry into the stationary phase, when the cell density is high, and this prompted us to study cell density-dependent regulation in B. pseudomallei. A search of the B. pseudomallei genome led to identification of a quorum-sensing system involving the LuxI-LuxR homologs PmlI-PmlR. PmlI directed the synthesis of an N-acylhomoserine lactone identified as N-decanoylhomoserine lactone. A B. pseudomallei pmlI mutant was significantly less virulent than the parental strain in a murine model of infection by the intraperitoneal, subcutaneous, and intranasal routes. Inactivation of pmlI resulted in overproduction of MprA at the onset of the stationary phase. A wild-type phenotype was restored following complementation with pmlI or addition of cell-free culture supernatant. In contrast, there was no significant difference between the virulence of a B. pseudomallei mprA mutant and the virulence of the wild-type strain. These results suggest that the PmlI-PmlR quorum-sensing system of B. pseudomallei is essential for full virulence in a mouse model and downregulates the production of MprA at a high cell density.

scholarly journals Regulatory roles of psrA and rpoS in phenazine-1-carboxamide synthesis by Pseudomonas chlororaphis PCL1391

Microbiology ◽  
2006 ◽  
Vol 152 (1) ◽  
pp. 43-58 ◽  
Author(s):  
Geneviève Girard ◽  
E. Tjeerd van Rij ◽  
Ben J. J. Lugtenberg ◽  
Guido V. Bloemberg
Keyword(s):  
Quorum Sensing ◽  
Constitutive Expression ◽  
Homoserine Lactone ◽  
Pseudomonas Chlororaphis ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
New Genes ◽  
Regulatory Cascade ◽  
Quorum Sensing System ◽  
Microarray Analyses

Production of the secondary metabolite phenazine-1-carboxamide (PCN) by Pseudomonas chlororaphis PCL1391 is crucial for biocontrol activity against the phytopathogen Fusarium oxysporum f. sp. radicis lycopersici on tomato. Regulation of PCN production involves the two-component signalling system GacS/GacA, the quorum-sensing system PhzI/PhzR and the regulator PsrA. This paper reports that a functional rpoS is required for optimal PCN and N-hexanoyl-l-homoserine lactone (C6-HSL) production. Constitutive expression of rpoS is able to complement partially the defect of a psrA mutant for PCN and N-acylhomoserine lactone production. Western blotting shows that rpoS is regulated by gacS. Altogether, these results suggest the existence of a cascade consisting of gacS/gacA upstream of psrA and rpoS, which influence expression of phzI/phzR. Overproduction of phzR complements the effects on PCN and C6-HSL production of all mutations tested in the regulatory cascade, which shows that a functional quorum-sensing system is essential and sufficient for PCN synthesis. In addition, the relative amounts of PCN, phenazine-1-carboxylic acid and C6-HSL produced by rpoS and psrA mutants harbouring a constitutively expressed phzR indicate an even more complex network of interactions, probably involving other genes. Preliminary microarray analyses of the transcriptomics of the rpoS and psrA mutants support the model of regulation described in this study and allow identification of new genes that might be involved in secondary metabolism.

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