Identification and Characterization of a GDSL Esterase Gene Located Proximal to the swr Quorum-Sensing System of Serratia liquefaciens MG1

ABSTRACT Serratia liquefaciens MG1 employs the swr quorum-sensing system to control various functions, including production of extracellular enzymes and swarming motility. Here we report the sequencing of the swr flanking DNA regions. We identified a gene upstream of swrR and transcribed in the same direction, designated estA, which encodes an esterase that belongs to family II of lipolytic enzymes. EstA was heterologously expressed in Escherichia coli, and the substrate specificity of the enzyme was determined in crude extracts. With the aid of zymograms visualizing EstA on polyacrylamide gels and by the analysis of a transcriptional fusion of the estA promoter to the promoterless luxAB genes, we showed that expression of the esterase is not regulated by the swr quorum-sensing system. An estA mutant was generated and was found to exhibit growth defects on minimal medium containing Tween 20 or Tween 80 as the sole carbon source. Moreover, we show that the mutant produces greatly reduced amounts of N-acyl-homoserine lactone (AHL) signal molecules on Tween-containing medium compared with the wild type, suggesting that under certain growth conditions EstA may be important for providing the cell with precursors required for AHL biosynthesis.

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N-Acyl-l-Homoserine Lactone-Mediated Regulation of the Lip Secretion System inSerratia liquefaciens MG1

Journal of Bacteriology ◽

10.1128/jb.183.5.1805-1809.2001 ◽

2001 ◽

Vol 183 (5) ◽

pp. 1805-1809 ◽

Cited By ~ 54

Author(s):

Kathrin Riedel ◽

Thomas Ohnesorg ◽

Karen A. Krogfelt ◽

Thomas S. Hansen ◽

Kenji Omori ◽

...

Keyword(s):

Quorum Sensing ◽

Homoserine Lactone ◽

Secretion System ◽

Type I ◽

Extracellular Lipase ◽

Sensing System ◽

Serratia Liquefaciens ◽

Quorum Sensing System ◽

Insertion Mutants

ABSTRACT The analysis of Serratia liquefaciens MG1 ′luxAB insertion mutants that are responsive toN-butanoyl-l-homoserine lactone revealed that expression of lipB is controlled by the swrquorum-sensing system. LipB is part of the Lip exporter, a type I secretion system, which is responsible for the secretion of extracellular lipase, metalloprotease, and S-layer protein.

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Quorum Sensing Regulates Denitrification in Pseudomonas aeruginosa PAO1

Journal of Bacteriology ◽

10.1128/jb.00289-07 ◽

2007 ◽

Vol 189 (13) ◽

pp. 4969-4972 ◽

Cited By ~ 71

Author(s):

Masanori Toyofuku ◽

Nobuhiko Nomura ◽

Tatsuya Fujii ◽

Naoki Takaya ◽

Hideaki Maseda ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Homoserine Lactone ◽

Anaerobic Growth ◽

Signal Molecules ◽

Pseudomonas Aeruginosa Pao1 ◽

Sensing System ◽

Quorum Sensing System ◽

Denitrification Activity

ABSTRACT Anaerobic growth of Pseudomonas aeruginosa PAO1 was affected by quorum sensing. Deletion of genes that produce N-acyl-l-homoserine lactone signals resulted in an increase in denitrification activity, which was repressed by exogenous signal molecules. The effect of the las quorum-sensing system was dependent on the rhl quorum-sensing system in regulating denitrification.

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Determination of quorum sensing system via biosensor strains and virulence factors in fish pathogen Aeromonas hydrophila

Ege Journal of Fisheries and Aquatic Sciences ◽

10.12714/egejfas.37.1.04 ◽

2020 ◽

Vol 37 (1) ◽

pp. 29-36

Author(s):

Nurdan Filik ◽

Ayşegül Kubilay

Keyword(s):

Quorum Sensing ◽

Virulence Factors ◽

Aeromonas Hydrophila ◽

Homoserine Lactone ◽

Signaling Molecules ◽

Signal Molecules ◽

Signaling Molecule ◽

Sensing System ◽

Quorum Sensing System

Quorum Sensing is a system that produces critical virulence factors, virulent get bacteria and manages the disease as a result, and when they realize that the bacteria reach the majority they want by enabling them to communicate with the signal molecules themselves. In this study, Quorum Sensing system of Aeromonas hydrophila (2 strains) which is the causative agent of fish infection Motile Aeromonas Septicemia (MAS) disease was studied. In the strains, primarily the production of N-butanoyl-L-homoserine lactone (BHL) and N-(3-octododecanoyl)-L-homoserine lactone (OdDHL) signaling molecules was investigated via Chromobacterium violaceum CV026 and Agrobacterium tumafeciens NT1 biosensor strains. A. hydrophila produced BHL signaling molecule in assay committed using C. violaceum CV026 strain, producing OdDHL signaling molecule in assay committed using A. tumefaciens NT1 strain. A. hydrophila was investigated as phenotypically by the detection of BHL and OdDHL signaling molecules and in the presence of virulence factors controlled by quorum sensing system such as ramnolipid, elastase, protease, amylase, hemolysis production dependent on these molecules. The ramnolipid, protease, amylase and hemolysis activities of A. hydrophila strains were found to be positive. A. hydrophila has less elastase activity than Pseudomonas aeruginosa PAO1 control strain. Research has emphasizing A. hydrophila strains are within a population and that they have a of quorum sensing system, shown that they act collectively that determined they produces dangerous virulence factors that cause disease in fish.

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

Biofarmasi Journal of Natural Product Biochemistry ◽

10.13057/biofar/f040202 ◽

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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Characterization of a luxI/luxR-type quorum sensing system and N-acyl homoserine lactone-dependent regulation of exo-enzyme and antibacterial component production in Serratia plymuthica RVH1

Research in Microbiology ◽

10.1016/j.resmic.2006.11.012 ◽

2007 ◽

Cited By ~ 1

Author(s):

Rob Van Houdt ◽

Pieter Moons ◽

Abram Aertsen ◽

An Jansen ◽

Kristof Vanoirbeek ◽

...

Keyword(s):

Quorum Sensing ◽

Homoserine Lactone ◽

Acyl Homoserine Lactone ◽

Serratia Plymuthica ◽

Sensing System ◽

Quorum Sensing System ◽

Component Production

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Quorum-Sensing System and Stationary-Phase Sigma Factor (rpoS) of the Onion Pathogen Burkholderia cepacia Genomovar I Type Strain, ATCC 25416

Applied and Environmental Microbiology ◽

10.1128/aem.69.3.1739-1747.2003 ◽

2003 ◽

Vol 69 (3) ◽

pp. 1739-1747 ◽

Cited By ~ 56

Author(s):

Claudio Aguilar ◽

Iris Bertani ◽

Vittorio Venturi

Keyword(s):

Quorum Sensing ◽

Stationary Phase ◽

Sigma Factor ◽

Burkholderia Cepacia ◽

Type Strain ◽

Plant Pathogens ◽

Signal Molecules ◽

Strain Atcc ◽

Sensing System ◽

Quorum Sensing System

ABSTRACT Bacterial strains belonging to Burkholderia cepacia can be human opportunistic pathogens, plant pathogens, and plant growth promoting and have remarkable catabolic activity. B. cepacia consists of several genomovars comprising what is now known as the B. cepacia complex. Here we report the quorum-sensing system of a genomovar I onion rot type strain ATCC 25416. Quorum sensing is a cell-density-dependent regulatory response which involves the production of N-acyl homoserine lactone (HSL) signal molecules. The cep locus has been inactivated in the chromosome, and it has been shown that CepI is responsible for the biosynthesis of an N-hexanoyl HSL (C6-HSL) and an N-octanoyl HSL (C8-HSL) and that the cep locus regulates protease production as well as onion pathogenicity via the expression of a secreted polygalacturonase. A cep-lacZ-based sensor plasmid has been constructed and used to demonstrate that CepR responded to C6-HSL with only 15% of the molar efficiency of C8-HSL, that a cepR knockout mutant synthesized 70% less HSLs, and that CepR responded best towards long-chain HSLs. In addition, we also report the cloning and characterization of the stationary-phase sigma factor gene rpoS of B. cepacia ATCC 25416. It was established that quorum sensing in B. cepacia has a negative effect on rpoS expression as determined by using an rpoS-lacZ transcriptional fusion; on the other hand, rpoS-null mutants displayed no difference in the accumulation of HSL signal molecules.

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PqsE Functions Independently of PqsR-Pseudomonas Quinolone Signal and Enhances the rhl Quorum-Sensing System

Journal of Bacteriology ◽

10.1128/jb.00753-08 ◽

2008 ◽

Vol 190 (21) ◽

pp. 7043-7051 ◽

Cited By ~ 105

Author(s):

John M. Farrow ◽

Zoe M. Sund ◽

Matthew L. Ellison ◽

Dana S. Wade ◽

James P. Coleman ◽

...

Keyword(s):

Quorum Sensing ◽

Virulence Factors ◽

Opportunistic Pathogen ◽

Homoserine Lactone ◽

Chronic Infections ◽

Signaling Systems ◽

Sensing System ◽

Pseudomonas Quinolone Signal ◽

Quorum Sensing System ◽

Hostile Environments

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that causes both acute and chronic infections in immunocompromised individuals. This gram-negative bacterium produces a battery of virulence factors that allow it to infect and survive in many different hostile environments. The control of many of these virulence factors falls under the influence of one of three P. aeruginosa cell-to-cell signaling systems. The focus of this study, the quinolone signaling system, functions through the Pseudomonas quinolone signal (PQS), previously identified as 2-heptyl-3-hydroxy-4-quinolone. This signal binds to and activates the LysR-type transcriptional regulator PqsR (also known as MvfR), which in turn induces the expression of the pqsABCDE operon. The first four genes of this operon are required for PQS synthesis, but the fifth gene, pqsE, is not. The function of the pqsE gene is not known, but it is required for the production of multiple PQS-controlled virulence factors and for virulence in multiple models of infection. In this report, we show that PqsE can activate PQS-controlled genes in the absence of PqsR and PQS. Our data also suggest that the regulatory activity of PqsE requires RhlR and indicate that a pqsE mutant can be complemented for pyocyanin production by a large excess of exogenous N-butyryl homoserine lactone (C4-HSL). Finally, we show that PqsE enhances the ability of Escherichia coli expressing RhlR to respond to C4-HSL. Overall, our data lead us to conclude that PqsE functions as a regulator that is independent of PqsR and PQS but dependent on the rhl quorum-sensing system.

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

Journal of Bacteriology ◽

10.1128/jb.183.12.3537-3547.2001 ◽

2001 ◽

Vol 183 (12) ◽

pp. 3537-3547 ◽

Cited By ~ 87

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).

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

Journal of Bacteriology ◽

10.1128/jb.01054-07 ◽

2007 ◽

Vol 189 (22) ◽

pp. 8333-8338 ◽

Cited By ~ 53

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.

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