The impact of mutations in the quorum sensing systems of Aeromonas hydrophila, Vibrio anguillarum and Vibrio harveyi on their virulence towards gnotobiotically cultured Artemia franciscana

ABSTRACT In a process called quorum sensing, bacteria communicate using extracellular signal molecules termed autoinducers. Two parallel quorum-sensing systems have been identified in the marine bacterium Vibrio harveyi. System 1 consists of the LuxM-dependent autoinducer HAI-1 and the HAI-1 sensor, LuxN. System 2 consists of the LuxS-dependent autoinducer AI-2 and the AI-2 detector, LuxPQ. The related bacterium, Vibrio cholerae, a human pathogen, possesses System 2 (LuxS, AI-2, and LuxPQ) but does not have obvious homologues of V. harveyi System 1. Rather, System 1 of V. cholerae is made up of the CqsA-dependent autoinducer CAI-1 and a sensor called CqsS. Using a V. cholerae CAI-1 reporter strain we show that many other marine bacteria, including V. harveyi, produce CAI-1 activity. Genetic analysis of V. harveyi reveals cqsA and cqsS, and phenotypic analysis of V. harveyi cqsA and cqsS mutants shows that these functions comprise a third V. harveyi quorum-sensing system that acts in parallel to Systems 1 and 2. Together these communication systems act as a three-way coincidence detector in the regulation of a variety of genes, including those responsible for bioluminescence, type III secretion, and metalloprotease production.

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Quorum Sensing and Spoilage Potential of Psychrotrophic Enterobacteriaceae Isolated from Milk

BioMed Research International ◽

10.1155/2018/2723157 ◽

2018 ◽

Vol 2018 ◽

pp. 1-13 ◽

Cited By ~ 3

Author(s):

Maurilio Lopes Martins ◽

Uelinton Manoel Pinto ◽

Katharina Riedel ◽

Maria Cristina Dantas Vanetti

Keyword(s):

Escherichia Coli ◽

Quorum Sensing ◽

16S Rdna ◽

Aeromonas Hydrophila ◽

Vibrio Harveyi ◽

Raw Milk ◽

Homoserine Lactone ◽

Positive Control ◽

Homoserine Lactones ◽

Acyl Homoserine Lactones

The 16S rDNA of six psychrotrophic Enterobacteriaceae isolated from cold raw milk were sequenced and the isolate 039 was identified asPantoeasp., isolates 059, 068, and 071 were identified asHafnia alvei, 067 was identified asEnterobactersp., and 099 was identified asAeromonas hydrophila. They presented different spoilage potentials in milk withA. hydrophila099 being the most deteriorative. OnlyPantoeasp. 039 was not able to induce the quorum sensing monitor strains of acyl homoserine lactones (AHLs). ThehalIgene, which encodes the AHL synthase inH. alvei, was identified in the isolates 059, 067, 068, and 071. After initial sequencing characterization and cloning, this gene showed its function by the heterologous synthesis of N-hexanoyl-DL-homoserine lactone and N-3-oxohexanoyl-L-homoserine lactone inEscherichia coli. In addition to producing AHLs,A. hydrophila099 produced AI-2 in higher level than the assay’s positive controlVibrio harveyiBB120. Therefore, Enterobacteriaceae strains isolated from cooled raw milk produce a rich array of signaling molecules that may influence bacterial traits in the milk environment.

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The impact of quorum sensing on the virulence of Aeromonas hydrophila and Aeromonas salmonicida towards burbot (Lota lota L.) larvae

Veterinary Microbiology ◽

10.1016/j.vetmic.2012.03.014 ◽

2012 ◽

Vol 159 (1-2) ◽

pp. 77-82 ◽

Cited By ~ 40

Author(s):

F.M.I. Natrah ◽

Md. Iftakharul Alam ◽

Sushant Pawar ◽

A. Shiri Harzevili ◽

Nancy Nevejan ◽

...

Keyword(s):

Quorum Sensing ◽

Aeromonas Hydrophila ◽

Aeromonas Salmonicida ◽

Lota Lota ◽

The Impact

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Quorum Sensing-Disrupting Brominated Furanones Protect the Gnotobiotic Brine Shrimp Artemia franciscana from Pathogenic Vibrio harveyi, Vibrio campbellii, and Vibrio parahaemolyticus Isolates

Applied and Environmental Microbiology ◽

10.1128/aem.00753-06 ◽

2006 ◽

Vol 72 (9) ◽

pp. 6419-6423 ◽

Cited By ~ 126

Author(s):

Tom Defoirdt ◽

Roselien Crab ◽

Thomas K. Wood ◽

Patrick Sorgeloos ◽

Willy Verstraete ◽

...

Keyword(s):

Quorum Sensing ◽

Vibrio Parahaemolyticus ◽

Brine Shrimp ◽

Vibrio Harveyi ◽

Artemia Franciscana ◽

Autoinducer 2 ◽

Pathogenic Vibrio ◽

Challenge Tests ◽

Vibrio Campbellii

ABSTRACT Autoinducer 2 (AI-2) quorum sensing was shown before to regulate the virulence of Vibrio harveyi towards the brine shrimp Artemia franciscana. In this study, several different pathogenic V. harveyi, Vibrio campbellii, and Vibrio parahaemolyticus isolates were shown to produce AI-2. Furthermore, disruption of AI-2 quorum sensing by a natural and a synthetic brominated furanone protected gnotobiotic Artemia from the pathogenic isolates in in vivo challenge tests.

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The phosphotransferase VanU represses expression of four qrr genes antagonizing VanO-mediated quorum-sensing regulation in Vibrio anguillarum

Microbiology ◽

10.1099/mic.0.051011-0 ◽

2011 ◽

Vol 157 (12) ◽

pp. 3324-3339 ◽

Cited By ~ 12

Author(s):

Barbara Weber ◽

Kristoffer Lindell ◽

Samir El Qaidi ◽

Erik Hjerde ◽

Nils-Peder Willassen ◽

...

Keyword(s):

Quorum Sensing ◽

Cell Density ◽

Stress Responses ◽

Aquatic Environment ◽

Response Regulator ◽

Vibrio Anguillarum ◽

Acylhomoserine Lactone ◽

Sensing Systems ◽

Small Regulatory Rnas ◽

Low Cell Density

Vibrio anguillarum utilizes quorum sensing to regulate stress responses required for survival in the aquatic environment. Like other Vibrio species, V. anguillarum contains the gene qrr1, which encodes the ancestral quorum regulatory RNA Qrr1, and phosphorelay quorum-sensing systems that modulate the expression of small regulatory RNAs (sRNAs) that destabilize mRNA encoding the transcriptional regulator VanT. In this study, three additional Qrr sRNAs were identified. All four sRNAs were positively regulated by σ54 and the σ54-dependent response regulator VanO, and showed a redundant activity. The Qrr sRNAs, together with the RNA chaperone Hfq, destabilized vanT mRNA and modulated expression of VanT-regulated genes. Unexpectedly, expression of all four qrr genes peaked at high cell density, and exogenously added N-acylhomoserine lactone molecules induced expression of the qrr genes at low cell density. The phosphotransferase VanU, which phosphorylates and activates VanO, repressed expression of the Qrr sRNAs and stabilized vanT mRNA. A model is presented proposing that VanU acts as a branch point, aiding cross-regulation between two independent phosphorelay systems that activate or repress expression of the Qrr sRNAs, giving flexibility and precision in modulating VanT expression and inducing a quorum-sensing response to stresses found in a constantly changing aquatic environment.

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The Phosphorylation Flow of the Vibrio harveyi Quorum-Sensing Cascade Determines Levels of Phenotypic Heterogeneity in the Population

Journal of Bacteriology ◽

10.1128/jb.02544-14 ◽

2015 ◽

Vol 197 (10) ◽

pp. 1747-1756 ◽

Cited By ~ 29

Author(s):

Laure Plener ◽

Nicola Lorenz ◽

Matthias Reiger ◽

Tiago Ramalho ◽

Ulrich Gerland ◽

...

Keyword(s):

Quorum Sensing ◽

Single Cell ◽

Molecular Design ◽

Vibrio Harveyi ◽

Phenotypic Heterogeneity ◽

Communication Process ◽

Signaling Cascade ◽

Homogeneous Population ◽

Content Type ◽

The Impact

ABSTRACTQuorum sensing (QS) is a communication process that enables a bacterial population to coordinate and synchronize specific behaviors. The bioluminescent marine bacteriumVibrio harveyiintegrates three autoinducer (AI) signals into one quorum-sensing cascade comprising a phosphorelay involving three hybrid sensor kinases: LuxU; LuxO, an Hfq/small RNA (sRNA) switch; and the transcriptional regulator LuxR. Using a new set ofV. harveyimutants lacking genes for the AI synthases and/or sensors, we assayed the activity of the quorum-sensing cascade at the population and single-cell levels, with a specific focus on signal integration and noise levels. We found that the ratios of kinase activities to phosphatase activities of the three sensors and, hence, the extent of phosphorylation of LuxU/LuxO are important not only for the signaling output but also for the degree of noise in the system. The pools of phosphorylated LuxU/LuxO per cell directly determine the amounts of sRNAs produced and, consequently, the copy number of LuxR, generating heterogeneous quorum-sensing activation at the single-cell level. We conclude that the ability to drive the heterogeneous expression of QS-regulated genes inV. harveyiis an inherent feature of the architecture of the QS cascade.IMPORTANCEV. harveyipossesses one of the most complex quorum-sensing (QS) cascades known, using three different autoinducers (AIs) to control the induction of, e.g., bioluminescence, virulence factors, and biofilm and exoprotease production. We constructed variousV. harveyimutants to study the impact of each component and subsystem of the QS signaling cascade on QS activation at the population and single-cell levels. We found that the output was homogeneous only in the presence of all AIs. In the absence of any one AI, QS activation varied from cell to cell, resulting in phenotypic heterogeneity. This study elucidates a molecular design principle which enables a tightly integrated signaling cascade to control the expression of diverse phenotypes within a genetically homogeneous population.

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