Methods for Measuring the Production of Quorum Sensing Signal Molecules

2018 ◽  
pp. 1-15
Author(s):  
Manuel Alcalde-Rico ◽  
José Luis Martínez
Keyword(s):  
Quorum Sensing ◽  
Signal Molecules

scholarly journals A Bacterial Tower of Babel: Quorum-Sensing Signaling Diversity and Its Evolution

2020 ◽  
Vol 74 (1) ◽  
pp. 587-606 ◽  
Author(s):  
Nitzan Aframian ◽  
Avigdor Eldar
Keyword(s):  
Quorum Sensing ◽  
Social Interactions ◽  
Signal Molecules ◽  
Allelic Polymorphism ◽  
Dependent Manner ◽  
Tower Of Babel ◽  
Cognate Receptor ◽  
Wide Range ◽  
Family Code ◽  
Bacterial Groups

Quorum sensing is a process in which bacteria secrete and sense a diffusible molecule, thereby enabling bacterial groups to coordinate their behavior in a density-dependent manner. Quorum sensing has evolved multiple times independently, utilizing different molecular pathways and signaling molecules. A common theme among many quorum-sensing families is their wide range of signaling diversity—different variants within a family code for different signal molecules with a cognate receptor specific to each variant. This pattern of vast allelic polymorphism raises several questions—How do different signaling variants interact with one another? How is this diversity maintained? And how did it come to exist in the first place? Here we argue that social interactions between signaling variants can explain the emergence and persistence of signaling diversity throughout evolution. Finally, we extend the discussion to include cases where multiple diverse systems work in concert in a single bacterium.

scholarly journals Peptide signaling without feedback in signal production operates as a true quorum sensing communication system in Bacillus subtilis

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Iztok Dogsa ◽  
Mihael Spacapan ◽  
Anna Dragoš ◽  
Tjaša Danevčič ◽  
Žiga Pandur ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Quorum Sensing ◽  
Cell Density ◽  
Communication System ◽  
Communication Systems ◽  
Feedback Loop ◽  
Signal Molecules ◽  
Specific Cell ◽  
Sharp Transition

AbstractBacterial quorum sensing (QS) is based on signal molecules (SM), which increase in concentration with cell density. At critical SM concentration, a variety of adaptive genes sharply change their expression from basic level to maximum level. In general, this sharp transition, a hallmark of true QS, requires an SM dependent positive feedback loop, where SM enhances its own production. Some communication systems, like the peptide SM-based ComQXPA communication system of Bacillus subtilis, do not have this feedback loop and we do not understand how and if the sharp transition in gene expression is achieved. Based on experiments and mathematical modeling, we observed that the SM peptide ComX encodes the information about cell density, specific cell growth rate, and even oxygen concentration, which ensure power-law increase in SM production. This enables together with the cooperative response to SM (ComX) a sharp transition in gene expression level and this without the SM dependent feedback loop. Due to its ultra-sensitive nature, the ComQXPA can operate at SM concentrations that are 100–1000 times lower than typically found in other QS systems, thereby substantially reducing the total metabolic cost of otherwise expensive ComX peptide.

scholarly journals Signal Integration in Quorum Sensing Enables Cross-Species Induction of Virulence in Pectobacterium wasabiae

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Rita S. Valente ◽  
Pol Nadal-Jimenez ◽  
André F. P. Carvalho ◽  
Filipe J. D. Vieira ◽  
Karina B. Xavier
Keyword(s):  
Signal Transduction ◽  
Quorum Sensing ◽  
Plant Pathogen ◽  
Bacterial Species ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Interspecies Interactions ◽  
Major Factors

ABSTRACT Bacterial communities can sense their neighbors, regulating group behaviors in response to cell density and environmental changes. The diversity of signaling networks in a single species has been postulated to allow custom responses to different stimuli; however, little is known about how multiple signals are integrated and the implications of this integration in different ecological contexts. In the plant pathogen Pectobacterium wasabiae (formerly Erwinia carotovora), two signaling networks—the N-acyl homoserine lactone (AHL) quorum-sensing system and the Gac/Rsm signal transduction pathway—control the expression of secreted plant cell wall-degrading enzymes, its major virulence determinants. We show that the AHL system controls the Gac/Rsm system by affecting the expression of the regulatory RNA RsmB. This regulation is mediated by ExpR2, the quorum-sensing receptor that responds to the P. wasabiae cognate AHL but also to AHLs produced by other bacterial species. As a consequence, this level of regulation allows P. wasabiae to bypass the Gac-dependent regulation of RsmB in the presence of exogenous AHLs or AHL-producing bacteria. We provide in vivo evidence that this pivotal role of RsmB in signal transduction is important for the ability of P. wasabiae to induce virulence in response to other AHL-producing bacteria in multispecies plant lesions. Our results suggest that the signaling architecture in P. wasabiae was coopted to prime the bacteria to eavesdrop on other bacteria and quickly join the efforts of other species, which are already exploiting host resources. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone receptors with apparently the same regulatory functions. Our work revealed that the receptor with the broadest signal specificity is also responsible for establishing the link between the main signaling pathways regulating virulence in P. wasabiae. This link is essential to provide P. wasabiae with the ability to induce virulence earlier in response to higher densities of other bacterial species. We further present in vivo evidence that this novel regulatory link enables P. wasabiae to join related bacteria in the effort to degrade host tissue in multispecies plant lesions. Our work provides support for the hypothesis that interspecies interactions are among the major factors influencing the network architectures observed in bacterial quorum-sensing pathways. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone receptors with apparently the same regulatory functions. Our work revealed that the receptor with the broadest signal specificity is also responsible for establishing the link between the main signaling pathways regulating virulence in P. wasabiae. This link is essential to provide P. wasabiae with the ability to induce virulence earlier in response to higher densities of other bacterial species. We further present in vivo evidence that this novel regulatory link enables P. wasabiae to join related bacteria in the effort to degrade host tissue in multispecies plant lesions. Our work provides support for the hypothesis that interspecies interactions are among the major factors influencing the network architectures observed in bacterial quorum-sensing pathways.

Identification of quorum-sensing signal molecules and the LuxRI homologs in fish pathogen Edwardsiella tarda

2004 ◽  
Vol 98 (4) ◽  
pp. 274-281 ◽  
Author(s):  
Tomohiro Morohoshi ◽  
Tadanori Inaba ◽  
Norihiro Kato ◽  
Kinya Kanai ◽  
Tsukasa Ikeda
Keyword(s):  
Quorum Sensing ◽  
Edwardsiella Tarda ◽  
Signal Molecules ◽  
Fish Pathogen

scholarly journals Quorum Sensing of Acidophiles: A Communication System in Microorganisms

2021 ◽  
Author(s):  
Xueyan Gao ◽  
Jianqiang Lin ◽  
Linxu Chen ◽  
Jianqun Lin ◽  
Xin Pang
Keyword(s):  
Quorum Sensing ◽  
Population Density ◽  
Intercellular Communication ◽  
Communication System ◽  
Communication Systems ◽  
Biological Function ◽  
Regulatory Mechanism ◽  
Signal Molecules ◽  
Acidic Environment ◽  
Cell Cooperation

Communication is important for organisms living in nature. Quorum sensing system (QS) are intercellular communication systems that promote the sociality of microbes. Microorganisms could promote cell-to-cell cooperation and population density to adapt to the changing environment through QS-mediated regulation that is dependent on the secretion and the detection of signal molecules (or called autoinducers). QS system is also discovered in acidophiles, a microorganism that is widely used in the bioleaching industry and can live in an acidic environment. An example is the LuxI/R-like QS system (AfeI/R) that has been reported in the chemoautotrophic species of the genus Acidithiobacillus. In this chapter, we will introduce the types and distribution of the QS system, and the biological function and regulatory mechanism of QS in acidophiles. We will also discuss the potential ecological function of QS system and the application value of the QS system in the control and regulation of the bioleaching process in the related industries and acid mine damage.

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

2003 ◽  
Vol 69 (3) ◽  
pp. 1739-1747 ◽  
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.

Occurrence of Proteolytic Activity and N-Acyl-Homoserine Lactone Signals in the Spoilage of Aerobically Chill-Stored Proteinaceous Raw Foods

2006 ◽  
Vol 69 (11) ◽  
pp. 2729-2737 ◽  
Author(s):  
M. LIU ◽  
J. M. GRAY ◽  
M. W. GRIFFITHS
Keyword(s):  
Quorum Sensing ◽  
Proteolytic Activity ◽  
Food Systems ◽  
Bacterial Flora ◽  
Homoserine Lactone ◽  
Food Samples ◽  
Clear Correlation ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Raw Foods

Proteolytic pseudomonads dominate the spoilage flora of aerobically chill-stored proteinaceous raw foods. Proteolysis during spoilage of these food systems affects both food quality and the dynamics of the bacterial community because it increases the availability of nutrients to the community as a whole. Quorum sensing, or cell-cell signaling, is associated closely with ecological interactions among bacteria in mixed communities. The potential role of quorum sensing in proteolytic food spoilage was examined, based on the evaluation of N-acyl-homoserine lactone (AHL) signal molecules. The occurrence of proteolytic activity and AHL signals was studied during spoilage of aerobically chill-stored ground beef, fish, chicken, and raw milk. Pseudomonads dominated the psychrotrophic flora, followed distantly by members of the Enterobacteriaceae. The growth of pseudomonads was correlated with the occurrence of proteolytic activity in all food systems. AHL concentration began increasing significantly only after the onset of proteolytic activity. Widely divergent AHL profiles were revealed by thin-layer chromatography analysis of the different food samples, and these profiles were likely determined by the undefined bacterial flora in these systems and by the characterized pseudomonads and Enterobacteriaceae. Although Hafnia alvei was a major component of the Enterobacteriaceae flora in all foods tested and a strong AHL producer, the signal molecules produced by H. alvei strain EB1 did not influence protease production by Pseudomonas fluorescens strain 395 in vitro. These results do not indicate any clear correlation between the overall detectable AHL signal molecules accumulated in the food samples and proteolytic activity.

scholarly journals Interference with Pseudomonas aeruginosa Quorum Sensing and Virulence by the Mycobacterial Pseudomonas Quinolone Signal Dioxygenase AqdC in Combination with the N-Acylhomoserine Lactone Lactonase QsdA

2019 ◽  
Vol 87 (10) ◽  
Author(s):  
Franziska S. Birmes ◽  
Ruth Säring ◽  
Miriam C. Hauke ◽  
Niklas H. Ritzmann ◽  
Steffen L. Drees ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Rhodococcus Erythropolis ◽  
Quorum Quenching ◽  
Signal Molecules ◽  
Content Type ◽  
Acylhomoserine Lactone ◽  
Regulatory Effects ◽  
Epithelial Lung Cells

ABSTRACT The nosocomial pathogen Pseudomonas aeruginosa regulates its virulence via a complex quorum sensing network, which, besides N-acylhomoserine lactones, includes the alkylquinolone signal molecules 2-heptyl-3-hydroxy-4(1H)-quinolone (Pseudomonas quinolone signal [PQS]) and 2-heptyl-4(1H)-quinolone (HHQ). Mycobacteroides abscessus subsp. abscessus, an emerging pathogen, is capable of degrading the PQS and also HHQ. Here, we show that although M. abscessus subsp. abscessus reduced PQS levels in coculture with P. aeruginosa PAO1, this did not suffice for quenching the production of the virulence factors pyocyanin, pyoverdine, and rhamnolipids. However, the levels of these virulence factors were reduced in cocultures of P. aeruginosa PAO1 with recombinant M. abscessus subsp. massiliense overexpressing the PQS dioxygenase gene aqdC of M. abscessus subsp. abscessus, corroborating the potential of AqdC as a quorum quenching enzyme. When added extracellularly to P. aeruginosa cultures, AqdC quenched alkylquinolone and pyocyanin production but induced an increase in elastase levels. When supplementing P. aeruginosa cultures with QsdA, an enzyme from Rhodococcus erythropolis which inactivates N-acylhomoserine lactone signals, rhamnolipid and elastase levels were quenched, but HHQ and pyocyanin synthesis was promoted. Thus, single quorum quenching enzymes, targeting individual circuits within a complex quorum sensing network, may also elicit undesirable regulatory effects. Supernatants of P. aeruginosa cultures grown in the presence of AqdC, QsdA, or both enzymes were less cytotoxic to human epithelial lung cells than supernatants of untreated cultures. Furthermore, the combination of both aqdC and qsdA in P. aeruginosa resulted in a decline of Caenorhabditis elegans mortality under P. aeruginosa exposure.

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