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

2015 ◽  
Vol 197 (10) ◽  
pp. 1747-1756 ◽  
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.

scholarly journals Quorum Sensing Regulates the Osmotic Stress Response in Vibrio harveyi

2014 ◽  
Vol 197 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Julia C. van Kessel ◽  
Steven T. Rutherford ◽  
Jian-Ping Cong ◽  
Sofia Quinodoz ◽  
James Healy ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Osmotic Stress ◽  
Glycine Betaine ◽  
Vibrio Harveyi ◽  
Communication Process ◽  
Content Type ◽  
Collective Behaviors ◽  
Expression Of Genes ◽  
Osmotic Stress Response ◽  
Genes Encoding

Bacteria use a chemical communication process called quorum sensing to monitor cell density and to alter behavior in response to fluctuations in population numbers. Previous studies withVibrio harveyihave shown that LuxR, the master quorum-sensing regulator, activates and represses >600 genes. These include six genes that encode homologs of theEscherichia coliBet and ProU systems for synthesis and transport, respectively, of glycine betaine, an osmoprotectant used during osmotic stress. Here we show that LuxR activates expression of the glycine betaine operonbetIBA-proXWV, which enhances growth recovery under osmotic stress conditions. BetI, an autorepressor of theV. harveyibetIBA-proXWVoperon, activates the expression of genes encoding regulatory small RNAs that control quorum-sensing transitions. Connecting quorum-sensing and glycine betaine pathways presumably enablesV. harveyito tune its execution of collective behaviors to its tolerance to stress.

Using colour semiotics to explore colour meanings

2018 ◽  
Vol 21 (1) ◽  
pp. 101-117 ◽  
Author(s):  
Hannele Kauppinen-Räisänen ◽  
Marie-Nathalie Jauffret
Keyword(s):  
Visual Cues ◽  
Current Knowledge ◽  
Underlying Mechanism ◽  
Communication Process ◽  
Alternative View ◽  
Conceptual Approach ◽  
Content Type ◽  
Marketing Activities ◽  
Indexical Sign ◽  
The Impact

Purpose The impact of colour is acknowledged within the marketing field. However, research on colour communication is limited, with most prior studies focusing on pre-defined meanings or colour associations. The purpose of this paper is to reveal insights into colour meaning and propose an alternative view to understanding colour communication. Design/methodology/approach The study takes a conceptual approach and proposes Peircean semiotics to understand colour communication. The proposed framework is applied to analyse a set of colour meanings detected by prior colour research. Findings The study elucidates the underlying mechanism of how colour is read and interpreted in various marketing activities, and how meaning is conveyed. This study addresses this mechanism by identifying colour semantics and colour as a symbolic, iconic and indexical sign. Research limitations/implications The study contributes to the scholarly knowledge of colour in marketing. It enriches the understanding of how consumers interpret representations of single visual signs expressed in contexts such as products, brands and brand packaging to make informed product decisions. Practical implications By understanding consumer interpretation as a stage in the communication process, marketers can develop more informed marketing activities to communicate the intended meanings. This may well strengthen the brand identity and contribute to the perceived brand value. Originality/value By elaborating on how colours convey meanings and the mechanism that explains such meanings, this study demonstrates that colour meaning is far more than mere association. The study contributes to the current knowledge of colour by facilitating a deeper understanding of how consumers interpret representations of single visual cues expressed in various contexts.

scholarly journals Hierarchical Transcriptional Control of the LuxR Quorum-Sensing Regulon of Vibrio harveyi

2020 ◽  
Vol 202 (14) ◽  
Author(s):  
Ryan R. Chaparian ◽  
Alyssa S. Ball ◽  
Julia C. van Kessel
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Quorum Sensing ◽  
Cell Density ◽  
Regulatory Networks ◽  
Vibrio Harveyi ◽  
Sugar Transport ◽  
Content Type ◽  
Second Tier

ABSTRACT In vibrios, quorum sensing controls hundreds of genes that are required for cell density-specific behaviors including bioluminescence, biofilm formation, competence, secretion, and swarming motility. The central transcription factor in the quorum-sensing pathway is LuxR/HapR, which directly regulates ∼100 genes in the >400-gene regulon of Vibrio harveyi. Among these directly controlled genes are 15 transcription factors, which we predicted would comprise the second tier in the hierarchy of the LuxR regulon. We confirmed that LuxR binds to the promoters of these genes in vitro and quantified the extent of LuxR activation or repression of transcript levels. Transcriptome sequencing (RNA-seq) indicates that most of these transcriptional regulators control only a few genes, with the exception of MetJ, which is a global regulator. The genes regulated by these transcription factors are predicted to be involved in methionine and thiamine biosynthesis, membrane stability, RNA processing, c-di-GMP degradation, sugar transport, and other cellular processes. These data support a hierarchical model in which LuxR directly regulates 15 transcription factors that drive the second level of the gene expression cascade to influence cell density-dependent metabolic states and behaviors in V. harveyi. IMPORTANCE Quorum sensing is important for survival of bacteria in nature and influences the actions of bacterial groups. In the relatively few studied examples of quorum-sensing-controlled genes, these genes are associated with competition or cooperation in complex microbial communities and/or virulence in a host. However, quorum sensing in vibrios controls the expression of hundreds of genes, and their functions are mostly unknown or uncharacterized. In this study, we identify the regulators of the second tier of gene expression in the quorum-sensing system of the aquaculture pathogen Vibrio harveyi. Our identification of regulatory networks and metabolic pathways controlled by quorum sensing can be extended and compared to other Vibrio species to understand the physiology, ecology, and pathogenesis of these organisms.

scholarly journals Analysis of Activator and Repressor Functions Reveals the Requirements for Transcriptional Control by LuxR, the Master Regulator of Quorum Sensing in Vibrio harveyi

mBio ◽  
2013 ◽  
Vol 4 (4) ◽  
Author(s):  
Julia C. van Kessel ◽  
Luke E. Ulrich ◽  
Igor B. Zhulin ◽  
Bonnie L. Bassler
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Dna Binding ◽  
Quorum Sensing ◽  
Binding Site ◽  
Binding Sites ◽  
Vibrio Harveyi ◽  
Communication Process ◽  
Nucleotide Sequencing ◽  
Collective Behaviors

ABSTRACT LuxR-type transcription factors are the master regulators of quorum sensing in vibrios. LuxR proteins are unique members of the TetR superfamily of transcription factors because they activate and repress large regulons of genes. Here, we used chromatin immunoprecipitation and nucleotide sequencing (ChIP-seq) to identify LuxR binding sites in the Vibrio harveyi genome. Bioinformatics analyses showed that the LuxR consensus binding site at repressed promoters is a symmetric palindrome, whereas at activated promoters it is asymmetric and contains only half of the palindrome. Using a genetic screen, we isolated LuxR mutants that separated activation and repression functions at representative promoters. These LuxR mutants exhibit sequence-specific DNA binding defects that restrict activation or repression activity to subsets of target promoters. Altering the LuxR DNA binding site sequence to one more closely resembling the ideal LuxR consensus motif can restore in vivo function to a LuxR mutant. This study provides a mechanistic understanding of how a single protein can recognize a variety of binding sites to differentially regulate gene expression. IMPORTANCE Bacteria use the cell-cell communication process called quorum sensing to regulate collective behaviors. In vibrios, LuxR-type transcription factors control the quorum-sensing gene expression cascade. LuxR-type proteins are structural homologs of TetR-type transcription factors. LuxR proteins were assumed to function analogously to TetR proteins, which typically bind to a single conserved binding site to repress transcription of one or two genes. We find here that unlike TetR proteins, LuxR acts a global regulator, directly binding upstream of and controlling more than 100 genes. Again unlike TetR, LuxR functions as both an activator and a repressor, and these two activities can be separated by mutagenesis. Finally, the consensus binding motifs driving LuxR-activated and -repressed genes are distinct. This work shows that LuxR, although structurally similar to TetR, has evolved unique features enabling it to differentially control a large regulon of genes in response to quorum-sensing cues.

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 Toward dialogue through a holistic measuring framework – the impact of social media on risk communication in the COVID-19

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ruilin Zhu ◽  
Yanqing Song ◽  
Shuang He ◽  
Xuan Hu ◽  
Wangsu Hu ◽  
...  
Keyword(s):  
Social Media ◽  
Risk Communication ◽  
Communication Process ◽  
Content Type ◽  
Dialogic Relationships ◽  
Full Picture ◽  
Power Measurements ◽  
The Impact ◽  
Dialogic Theory ◽  
The Relationship

PurposeDespite the huge potential of social media, its functionality and impact for enhanced risk communication remain unclear. Drawing on dialogic theory by integrating both “speak from power” and “speak to power” measurements, the article aims to propose a systematic framework to address this issue.Design/methodology/approachThe impact of social media on risk communication is measured by the correlation between “speak from power” and “speak to power” levels, where the former primarily spoke to two facets of the risk communication process – rapidness and attentiveness, and the latter was benchmarked against popularity and commitment. The framework was empirically validated with data relating to coronavirus disease (COVID-19) risk communication in 25,024 selected posts on 17 official provincial Weibo accounts in China.FindingsThe analysis results suggest the relationship between the “speak from power” and “speak to power” is mixed rather than causality, which confirms that neither the outcome-centric nor the process-centric method alone can render a full picture of government–public interconnectivity. Besides, the proposed interconnectivity matrix reveals that two provinces have evidenced the formation of government–public mutuality, which provides empirical evidence that dialogic relationships could exist in social media during risk communication.Originality/valueThe authors' study proposed a prototype framework that underlines the need that the impact of social media on risk communication should and must be assessed through a combination of process and outcome or interconnectivity. The authors further divide the impact of social media on risk communication into dialogue enabler, “speak from power” booster, “speak to power” channel and mass media alternative.

scholarly journals The Apparent Quorum-Sensing Inhibitory Activity of Pyrogallol Is a Side Effect of Peroxide Production

2013 ◽  
Vol 57 (6) ◽  
pp. 2870-2873 ◽  
Author(s):  
Tom Defoirdt ◽  
Gde Sasmita Julyantoro Pande ◽  
Kartik Baruah ◽  
Peter Bossier
Keyword(s):  
Quorum Sensing ◽  
Side Effect ◽  
Brine Shrimp ◽  
Vibrio Harveyi ◽  
Macrobrachium Rosenbergii ◽  
Therapeutic Index ◽  
Therapeutic Agents ◽  
Quorum Sensing Inhibition ◽  
Content Type ◽  
Low Toxicity

ABSTRACTThere currently is more and more interest in the use of natural products, such as tea polyphenols, as therapeutic agents. The polyphenol compound pyrogallol has been reported before to inhibit quorum-sensing-regulated bioluminescence inVibrio harveyi. Here, we report that the addition of 10 mg · liter−1pyrogallol protects both brine shrimp (Artemia franciscana) and giant river prawn (Macrobrachium rosenbergii) larvae from pathogenicVibrio harveyi, whereas the compound showed relatively low toxicity (therapeutic index of 10). We further demonstrate that the apparent quorum-sensing-disrupting activity is a side effect of the peroxide-producing activity of this compound rather than true quorum-sensing inhibition. Our results emphasize that verification of minor toxic effects by using sensitive methods and the use of appropriate controls are essential when characterizing compounds as being able to disrupt quorum sensing.

scholarly journals Secreted Proteases Control the Timing of Aggregative Community Formation in Vibrio cholerae

mBio ◽  
2021 ◽  
Author(s):  
Matthew Jemielita ◽  
Ameya A. Mashruwala ◽  
Julie S. Valastyan ◽  
Ned S. Wingreen ◽  
Bonnie L. Bassler
Keyword(s):  
Quorum Sensing ◽  
Vibrio Cholerae ◽  
Chemical Communication ◽  
Communication Process ◽  
Community Formation ◽  
Aggregate Formation ◽  
Content Type ◽  
Secreted Proteases

Bacteria can work as collectives to form multicellular communities. Vibrio cholerae , the bacterium that causes the disease cholera in humans, forms aggregated communities in liquid. Aggregate formation relies on a chemical communication process called quorum sensing.

scholarly journals Coculturing Bacteria Leads to Reduced Phenotypic Heterogeneities

2019 ◽  
Vol 85 (8) ◽  
Author(s):  
Jasmine Heyse ◽  
Benjamin Buysschaert ◽  
Ruben Props ◽  
Peter Rubbens ◽  
Andre G. Skirtach ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Raman Spectroscopy ◽  
Single Cell ◽  
Phenotypic Diversity ◽  
Microbial Interactions ◽  
Phenotypic Heterogeneity ◽  
Bacterial Populations ◽  
The Individual ◽  
Axenic Conditions ◽  
The Impact

ABSTRACT Isogenic bacterial populations are known to exhibit phenotypic heterogeneity at the single-cell level. Because of difficulties in assessing the phenotypic heterogeneity of a single taxon in a mixed community, the importance of this deeper level of organization remains relatively unknown for natural communities. In this study, we have used membrane-based microcosms that allow the probing of the phenotypic heterogeneity of a single taxon while interacting with a synthetic or natural community. Individual taxa were studied under axenic conditions, as members of a coculture with physical separation, and as a mixed culture. Phenotypic heterogeneity was assessed through both flow cytometry and Raman spectroscopy. Using this setup, we investigated the effect of microbial interactions on the individual phenotypic heterogeneities of two interacting drinking water isolates. Through flow cytometry we have demonstrated that interactions between these bacteria lead to a reduction of their individual phenotypic diversities and that this adjustment is conditional on the bacterial taxon. Single-cell Raman spectroscopy confirmed a taxon-dependent phenotypic shift due to the interaction. In conclusion, our data suggest that bacterial interactions may be a general driver of phenotypic heterogeneity in mixed microbial populations. IMPORTANCE Laboratory studies have shown the impact of phenotypic heterogeneity on the survival and functionality of isogenic populations. Because phenotypic heterogeneity plays an important role in pathogenicity and virulence, antibiotic resistance, biotechnological applications, and ecosystem properties, it is crucial to understand its influencing factors. An unanswered question is whether bacteria in mixed communities influence the phenotypic heterogeneity of their community partners. We found that coculturing bacteria leads to a reduction in their individual phenotypic heterogeneities, which led us to the hypothesis that the individual phenotypic diversity of a taxon is dependent on the community composition.

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