scholarly journals Bacterial quorum sensing allows graded responses to variations in density, on both individual and population scales

2019 ◽  
Author(s):  
Jennifer Rattray ◽  
Stephen Thomas ◽  
Yifei Wang ◽  
Sam P. Brown
Keyword(s):  
Quorum Sensing ◽  
Cell Mass ◽  
Cell Communication ◽  
Reaction Norms ◽  
Signal Molecules ◽  
Standard View ◽  
Functional Studies ◽  
Graded Responses ◽  
Bacterial Quorum ◽  
The Individual

ABSTRACTQuorum sensing (QS) is a mechanism of cell-to-cell communication via diffusible signal molecules that controls multiple secreted factors including virulence factors in bacterial pathogens [1,2]. While the standard view is that QS functions as a density-sensing mechanism, the functional and evolutionary context of QS continues to be disputed [3–11]. A critical step in assessing the various adaptive hypotheses is establishing the functional capacities and limits of QS. Current functional studies largely focus on a dichotomy of QS on/off (or, quorate / sub-quorate) states, despite the increasing amount of heterogeneity on a cellular scale [4,12–16], overlooking the potential for intermediate, graded responses. In this paper we explore the functional capacity of QS to resolve finely graded environmental densities and introduce the use of reaction norms as a way to holistically characterize QS response. Here we show that Pseudomonas aeruginosa can deliver a graded response to variation in environmental population density on both the population and individual scales. We further resolve the linear population response to be the product of two component cellular reaction norms: the likelihood of being responsive and the intensity of response. Overall, this work reveals that there is no critical cell mass or ‘quorum’, at which QS is activated on either the individual cell or population scale.

scholarly journals Phage-Encoded LuxR-Type Receptors Responsive to Host-Produced Bacterial Quorum-Sensing Autoinducers

2019 ◽  
Author(s):  
Justin E. Silpe ◽  
Bonnie L. Bassler
Keyword(s):  
Quorum Sensing ◽  
Pathogenic Bacteria ◽  
Cell Communication ◽  
Signal Molecules ◽  
Host Bacterium ◽  
Gram Negative ◽  
Collective Behaviors ◽  
Bacterial Quorum Sensing ◽  
Genes Encoding ◽  
Bacterial Quorum

AbstractQuorum sensing (QS) is a process of cell-to-cell communication that bacteria use to orchestrate collective behaviors. QS relies on the cell-density-dependent production, accumulation, and receptor-mediated detection of extracellular signaling molecules called autoinducers (AIs). Gram-negative bacteria commonly use N-acyl homoserine lactones (AHLs) as their AIs and they are detected by LuxR-type receptors. Often, LuxR-type receptors are insoluble when not bound to a cognate AI. In this report, we show that LuxR-type receptors are encoded on phage genomes and, in the cases we tested, the phage LuxR-type receptors bind to and are solubilized specifically by the AHL AI produced by the host bacterium. We do not yet know the viral activities that are controlled by these phage QS receptors, however, our observations, coupled with recent reports, suggest that their occurrence is more widespread than previously appreciated. Using receptor-mediated detection of QS AIs could enable phages to garner information concerning the population density status of their bacterial hosts. We speculate that such information can be exploited by phages to optimize the timing of execution of particular steps in viral infection.ImportanceBacteria communicate with chemical signal molecules to regulate group behaviors in a process called quorum sensing (QS). In this report, we find that genes encoding receptors for Gram-negative bacterial QS communication molecules are present on genomes of viruses that infect these bacteria. These viruses are called phages. We show that two phage-encoded receptors, like their bacterial counterparts, bind to the communication molecule produced by the host bacterium, suggesting that phages can “listen in” on their bacterial hosts. Interfering with bacterial QS and using phages to kill pathogenic bacteria represent attractive possibilities for development of new antimicrobials to combat pathogens that are resistant to traditional antibiotics. Our findings of interactions between phages and QS bacteria need consideration as new antimicrobial therapies are developed.

scholarly journals Phage-Encoded LuxR-Type Receptors Responsive to Host-Produced Bacterial Quorum-Sensing Autoinducers

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Justin E. Silpe ◽  
Bonnie L. Bassler
Keyword(s):  
Quorum Sensing ◽  
Pathogenic Bacteria ◽  
Cell Communication ◽  
Signal Molecules ◽  
Host Bacterium ◽  
Gram Negative ◽  
Collective Behaviors ◽  
Bacterial Quorum Sensing ◽  
Genes Encoding ◽  
Bacterial Quorum

ABSTRACT Quorum sensing (QS) is a process of cell-to-cell communication that bacteria use to orchestrate collective behaviors. QS relies on the cell-density-dependent production, accumulation, and receptor-mediated detection of extracellular signaling molecules called autoinducers (AIs). Gram-negative bacteria commonly use N-acyl homoserine lactones (AHLs) as their AIs, and they are detected by LuxR-type receptors. Often, LuxR-type receptors are insoluble when not bound to a cognate AI. In this report, we show that LuxR-type receptors are encoded on phage genomes, and in the cases we tested, the phage LuxR-type receptors bind to and are solubilized specifically by the AHL AI produced by the host bacterium. We do not yet know the viral activities that are controlled by these phage QS receptors; however, our observations, coupled with recent reports, suggest that their occurrence is more widespread than previously appreciated. Using receptor-mediated detection of QS AIs could enable phages to garner information concerning the population density status of their bacterial hosts. We speculate that such information can be exploited by phages to optimize the timing of execution of particular steps in viral infection. IMPORTANCE Bacteria communicate with chemical signal molecules to regulate group behaviors in a process called quorum sensing (QS). In this report, we find that genes encoding receptors for Gram-negative bacterial QS communication molecules are present on genomes of viruses that infect these bacteria. These viruses are called phages. We show that two phage-encoded receptors, like their bacterial counterparts, bind to the communication molecule produced by the host bacterium, suggesting that phages can “listen in” on their bacterial hosts. Interfering with bacterial QS and using phages to kill pathogenic bacteria represent attractive possibilities for development of new antimicrobials to combat pathogens that are resistant to traditional antibiotics. Our findings of interactions between phages and QS bacteria need consideration as new antimicrobial therapies are developed.

scholarly journals Mechanism of Stochastic Resonance in a Quorum Sensing Network Regulated by Small RNAs

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ya-nan Zhu ◽  
Jianwei Shen ◽  
Yong Xu
Keyword(s):  
Quorum Sensing ◽  
Stochastic Resonance ◽  
Small Rna ◽  
Small Rnas ◽  
Cell Communication ◽  
The Other ◽  
Important Process ◽  
Positive Role ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum

Bacterial quorum sensing (QS) is an important process of cell communication and more and more attention is paid to it. Moreover, the noises are ubiquitous in nature and often play positive role. In this paper, we investigate how the noise enhances the QS though the stochastic resonance (SR) and explain the mechanism of SR in this quorum sensing network. In addition, we also discuss the interaction between the small RNA and the other genes in this network and discover the biological importance.

Bacterial Foraging Optimization Algorithm with Quorum Sensing Mechanism

2014 ◽  
Vol 556-562 ◽  
pp. 3844-3848
Author(s):  
Hai Shen ◽  
Mo Zhang
Keyword(s):  
Quorum Sensing ◽  
Optimization Algorithm ◽  
Complex Adaptive Systems ◽  
Adaptive Systems ◽  
Cell Communication ◽  
Bacterial Foraging Optimization ◽  
Sensing Mechanism ◽  
Bacterial Foraging ◽  
Bacterial Quorum ◽  
Bacterial Foraging Optimization Algorithm

Quorum sensing is widely distributed in bacteria and make bacteria are similar to complex adaptive systems, with intelligent features such as emerging and non-linear, the ultimate expression of the adaptive to changes in the environment. Based on the phenomenon of bacterial quorum sensing and Bacterial Foraging Optimization Algorithm, some new optimization algorithms have been proposed. In this paper, it presents research situations, such as environment-dependent quorum sensing mechanism, quorum sensing mechanism with quantum behavior, cell-to-cell communication, multi-colony communication, density perception mechanism. Areas of future emphasis and direction in development were also pointed out.

scholarly journals Quorum-Sensing Mutations Affect Attachment and Stability of Burkholderia cenocepacia Biofilms

2005 ◽  
Vol 71 (9) ◽  
pp. 5208-5218 ◽  
Author(s):  
Kerry L. Tomlin ◽  
Rebecca J. Malott ◽  
Gordon Ramage ◽  
Douglas G. Storey ◽  
Pamela A. Sokol ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Cell Mass ◽  
Sodium Dodecyl ◽  
Burkholderia Cenocepacia ◽  
Structural Defects ◽  
Expression Vectors ◽  
Structural Development ◽  
The Individual

ABSTRACT Biofilm formation in Burkholderia cenocepacia has been shown to rely in part on acylhomoserine lactone-based quorum sensing. For many other bacterial species, it appears that both the initial adherence and the later stages of biofilm maturation are affected when quorum sensing pathways are inhibited. In this study, we examined the effects of mutations in the cepIR and cciIR quorum-sensing systems of Burkholderia cenocepacia K56-2 with respect to biofilm attachment and antibiotic resistance. We also examined the role of the cepIR system in biofilm stability and structural development. Using the high-throughput MBEC assay system to produce multiple equivalent biofilms, the biomasses of both the cepI and cepR mutant biofilms, measured by crystal violet staining, were less than half of the value observed for the wild-type strain. Attachment was partially restored upon providing functional gene copies via multicopy expression vectors. Surprisingly, neither the cciI mutant nor the double cciI cepI mutant was deficient in attachment, and restoration of the cciI gene resulted in less attachment than for the mutants. Meanwhile, the cciR mutant did show a significant reduction in attachment, as did the cciR cepIR mutant. While there was no change in antibiotic susceptibility with the individual cepIR and cciIR mutants, the cepI cciI mutant biofilms were more sensitive to ciprofloxacin. A significant increase in sensitivity to removal by sodium dodecyl sulfate was seen for the cepI and cepR mutants. Flow cell analysis of the individual cepIR mutant biofilms indicated that they were both structurally and temporally impaired in attachment and development. These results suggest that biofilm structural defects might be present in quorum-sensing mutants of B. cenocepacia that affect the stability and resistance of the adherent cell mass, providing a basis for future studies to design preventative measures against biofilm formation in this species, an important lung pathogen of cystic fibrosis patients.

scholarly journals Quorum sensing and social networking in the microbial world

2009 ◽  
Vol 6 (40) ◽  
pp. 959-978 ◽  
Author(s):  
Steve Atkinson ◽  
Paul Williams
Keyword(s):  
Quorum Sensing ◽  
Social Networking ◽  
Communication Networks ◽  
Cell Communication ◽  
Signal Molecules ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Microbial World ◽  
Rich Diversity ◽  
Intercellular Signalling

For many years, bacterial cells were considered primarily as selfish individuals, but, in recent years, it has become evident that, far from operating in isolation, they coordinate collective behaviour in response to environmental challenges using sophisticated intercellular communication networks. Cell-to-cell communication between bacteria is mediated by small diffusible signal molecules that trigger changes in gene expression in response to fluctuations in population density. This process, generally referred to as quorum sensing (QS), controls diverse phenotypes in numerous Gram-positive and Gram-negative bacteria. Recent advances have revealed that bacteria are not limited to communication within their own species but are capable of ‘listening in’ and ‘broadcasting to’ unrelated species to intercept messages and coerce cohabitants into behavioural modifications, either for the good of the population or for the benefit of one species over another. It is also evident that QS is not limited to the bacterial kingdom. The study of two-way intercellular signalling networks between bacteria and both uni- and multicellular eukaryotes as well as between eukaryotes is just beginning to unveil a rich diversity of communication pathways.

Quorum Sensing: A Primer for Food Microbiologists†

2004 ◽  
Vol 67 (5) ◽  
pp. 1053-1070 ◽  
Author(s):  
JAMES L. SMITH ◽  
PINA M. FRATAMICO ◽  
JOHN S. NOVAK
Keyword(s):  
Quorum Sensing ◽  
Cell Communication ◽  
Toxin Production ◽  
Clinical Aspects ◽  
Specific Cell ◽  
Cellular Functions ◽  
Signaling Mechanism ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum ◽  
Cell Densities

Quorum sensing is a signaling mechanism through which bacteria modulate a number of cellular functions (genes), including sporulation, biofilm formation, bacteriocin production, virulence responses, as well as others. Quorum sensing is a mechanism of cell-to-cell communication and is mediated by extracellular chemical signals generated by the bacteria when specific cell densities are reached. When the concentration of the signal (and cell population) is sufficiently high, the target gene or genes are either activated or repressed. Quorum sensing increases the ability of the bacteria to have access to nutrients or to more favorable environmental niches and enhances bacterial defenses against eukaryotic hosts, competing bacteria, and environmental stresses. The physiological and clinical aspects of quorum sensing have received considerable attention and have been studied at the molecular level. Little is known, however, on the role of quorum sensing in food spoilage or in the growth and/or toxin production of pathogens present in food. A number of compounds have been isolated or synthesized that antagonize quorum sensors, and application of these antagonists may potentially be useful in inhibiting the growth or virulence mechanisms of bacteria in different environments, including food. It is important that food microbiologists have an awareness and an understanding of the mechanisms involved in bacterial quorum sensing, since strategies targeting quorum sensing may offer a means to control the growth of undesirable bacteria in foods.

scholarly journals Look who's talking: communication and quorum sensing in the bacterial world

2007 ◽  
Vol 362 (1483) ◽  
pp. 1119-1134 ◽  
Author(s):  
Paul Williams ◽  
Klaus Winzer ◽  
Weng C Chan ◽  
Miguel Cámara
Keyword(s):  
Quorum Sensing ◽  
Bacterial Population ◽  
Response Regulator ◽  
Cell Communication ◽  
Threshold Concentration ◽  
Critical Threshold ◽  
Signal Molecules ◽  
Bacterial Cells ◽  
Environmental Threats ◽  
Generic Term

For many years bacteria were considered primarily as autonomous unicellular organisms with little capacity for collective behaviour. However, we now appreciate that bacterial cells are in fact, highly communicative. The generic term ‘quorum sensing’ has been adopted to describe the bacterial cell-to-cell communication mechanisms which co-ordinate gene expression usually, but not always, when the population has reached a high cell density. Quorum sensing depends on the synthesis of small molecules (often referred to as pheromones or autoinducers) that diffuse in and out of bacterial cells. As the bacterial population density increases, so does the synthesis of quorum sensing signal molecules, and consequently, their concentration in the external environment rises. Once a critical threshold concentration has been reached, a target sensor kinase or response regulator is activated (or repressed) so facilitating the expression of quorum sensing-dependent genes. Quorum sensing enables a bacterial population to mount a co-operative response that improves access to nutrients or specific environmental niches, promotes collective defence against other competitor prokaryotes or eukaryotic defence mechanisms and facilitates survival through differentiation into morphological forms better able to combat environmental threats. Quorum sensing also crosses the prokaryotic–eukaryotic boundary since quorum sensing-dependent signalling can be exploited or inactivated by both plants and mammals.

scholarly journals Saccharomyces cerevisiae Requires CFF1 To Produce 4-Hydroxy-5-Methylfuran-3(2H)-One, a Mimic of the Bacterial Quorum-Sensing Autoinducer AI-2

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Julie S. Valastyan ◽  
Christina M. Kraml ◽  
Istvan Pelczer ◽  
Thomas Ferrante ◽  
Bonnie L. Bassler
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quorum Sensing ◽  
Bacterial Species ◽  
Cell Communication ◽  
Communication Process ◽  
Signal Molecules ◽  
Catalytic Residue ◽  
Interspecies Communication ◽  
Content Type ◽  
Extracellular Signal

ABSTRACT Quorum sensing is a process of cell-to-cell communication that bacteria use to orchestrate collective behaviors. Quorum sensing depends on the production, release, and detection of extracellular signal molecules called autoinducers (AIs) that accumulate with increasing cell density. While most AIs are species specific, the AI called AI-2 is produced and detected by diverse bacterial species, and it mediates interspecies communication. We recently reported that mammalian cells produce an AI-2 mimic that can be detected by bacteria through the AI-2 receptor LuxP, potentially expanding the role of the AI-2 system to interdomain communication. Here, we describe a second molecule capable of interdomain signaling through LuxP, 4-hydroxy-5-methylfuran-3(2H)-one (MHF), that is produced by the yeast Saccharomyces cerevisiae. Screening the S. cerevisiae deletion collection revealed Cff1p, a protein with no known role, to be required for MHF production. Cff1p is proposed to be an enzyme, with structural similarity to sugar isomerases and epimerases, and substitution at the putative catalytic residue eliminated MHF production in S. cerevisiae. Sequence analysis uncovered Cff1p homologs in many species, primarily bacterial and fungal, but also viral, archaeal, and higher eukaryotic. Cff1p homologs from organisms from all domains can complement a cff1Δ S. cerevisiae mutant and restore MHF production. In all cases tested, the identified catalytic residue is conserved and required for MHF to be produced. These findings increase the scope of possibilities for interdomain interactions via AI-2 and AI-2 mimics, highlighting the breadth of molecules and organisms that could participate in quorum sensing. IMPORTANCE Quorum sensing is a cell-to-cell communication process that bacteria use to monitor local population density. Quorum sensing relies on extracellular signal molecules called autoinducers (AIs). One AI called AI-2 is broadly made by bacteria and used for interspecies communication. Here, we describe a eukaryotic AI-2 mimic, 4-hydroxy-5-methylfuran-3(2H)-one, (MHF), that is made by the yeast Saccharomyces cerevisiae, and we identify the Cff1p protein as essential for MHF production. Hundreds of viral, archaeal, bacterial, and eukaryotic organisms possess Cff1p homologs. This finding, combined with our results showing that homologs from all domains can replace S. cerevisiae Cff1p, suggests that like AI-2, MHF is widely produced. Our results expand the breadth of organisms that may participate in quorum-sensing-mediated interactions.

scholarly journals Bacterial Quorum Sensing and Microbial Community Interactions

mBio ◽  
2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Rhea G. Abisado ◽  
Saida Benomar ◽  
Jennifer R. Klaus ◽  
Ajai A. Dandekar ◽  
Josephine R. Chandler
Keyword(s):  
Quorum Sensing ◽  
Bacterial Infections ◽  
Molecular Mechanisms ◽  
Cell Communication ◽  
Microbial Interactions ◽  
Community Interactions ◽  
Bacterial Populations ◽  
Bacterial Quorum Sensing ◽  
A Cell ◽  
Bacterial Quorum

ABSTRACTMany bacteria use a cell-cell communication system called quorum sensing to coordinate population density-dependent changes in behavior. Quorum sensing involves production of and response to diffusible or secreted signals, which can vary substantially across different types of bacteria. In many species, quorum sensing modulates virulence functions and is important for pathogenesis. Over the past half-century, there has been a significant accumulation of knowledge of the molecular mechanisms, signal structures, gene regulons, and behavioral responses associated with quorum-sensing systems in diverse bacteria. More recent studies have focused on understanding quorum sensing in the context of bacterial sociality. Studies of the role of quorum sensing in cooperative and competitive microbial interactions have revealed how quorum sensing coordinates interactions both within a species and between species. Such studies of quorum sensing as a social behavior have relied on the development of “synthetic ecological” models that use nonclonal bacterial populations. In this review, we discuss some of these models and recent advances in understanding how microbes might interact with one another using quorum sensing. The knowledge gained from these lines of investigation has the potential to guide studies of microbial sociality in natural settings and the design of new medicines and therapies to treat bacterial infections.

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