The Experts below are selected from a list of 24366 Experts worldwide ranked by ideXlab platform
Robert P Ryan - One of the best experts on this subject based on the ideXlab platform.
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bacterial signal transduction by Cyclic di gmp and other nucleotide second messengers
Journal of Bacteriology, 2016Co-Authors: Regine Hengge, Urs Jenal, Robert P Ryan, Angelika Grundling, Fitnat H. YildizAbstract:ABSTRACT The first International Symposium on c-Di-GMP Signaling in Bacteria (22 to 25 March 2015, Harnack-Haus, Berlin, Germany) brought together 131 molecular microbiologists from 17 countries to discuss recent progress in our knowledge of bacterial nucleotide second messenger signaling. While the focus was on signal input, synthesis, degradation, and the striking diversity of the modes of action of the current second messenger paradigm, i.e., Cyclic Di-GMP (c-Di-GMP), “classics” like cAMP and (p)ppGpp were also presented, in novel facets, and more recent “newcomers,” such as c-di-AMP and c-AMP-GMP, made an impressive appearance. A number of clear trends emerged during the 30 talks, on the 71 posters, and in the lively discussions, including (i) c-Di-GMP control of the activities of various ATPases and phosphorylation cascades, (ii) extensive cross talk between c-Di-GMP and other nucleotide second messenger signaling pathways, and (iii) a stunning number of novel effectors for nucleotide second messengers that surprisingly include some long-known master regulators of developmental pathways. Overall, the conference made it amply clear that second messenger signaling is currently one of the most dynamic fields within molecular microbiology, with major impacts in research fields ranging from human health to microbial ecology.
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Targeting Cyclic Di-GMP signalling: a strategy to control biofilm formation?
Current pharmaceutical design, 2014Co-Authors: Delphine L. Caly, J. Maxwell Dow, Domenico Bellini, Martin A. Walsh, Robert P RyanAbstract:Cyclic Di-GMP is a second messenger found in almost all eubacteria that acts to regulate a wide range of functions including developmental transitions, adhesion and biofilm formation. Cyclic Di-GMP is synthesised from two GTP molecules by diguanylate cyclases that have a GGDEF domain and is degraded by phosphodiesterases with either an EAL or an HD-GYP domain. Proteins with these domains often contain additional signal input domains, suggesting that their enzymatic activity may be modulated as a response to different environmental or cellular cues. Cyclic Di-GMP exerts a regulatory action through binding to diverse receptors that include a small protein domain called PilZ, enzymatically inactive GGDEF, EAL or HD-GYP domains, transcription factors and riboswitches. In many bacteria, high cellular levels of Cyclic Di-GMP are associated with a sessile, biofilm lifestyle, whereas low levels of the nucleotide promote motility and virulence factor synthesis in pathogens. Elucidation of the roles of Cyclic Di-GMP signalling in biofilm formation has suggested strategies whereby modulation of the levels of the nucleotide or interference with signalling pathways may lead to inhibition of biofilm formation or promotion of biofilm dispersal. In this review we consider these approaches for the control of biofilm formation, beginning with an overview of Cyclic Di-GMP signalling and the different ways that it can act in regulation of biofilm dynamics.
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Novel Cyclic Di-GMP effectors of the YajQ protein family control bacterial virulence
PLoS pathogens, 2014Co-Authors: Delphine L. Caly, Yvonne Mccarthy, Sarah Murdoch, Joseph Ward, Melanie Febrer, J. Maxwell Dow, Robert P RyanAbstract:Bis-(3′,5′) Cyclic di-guanylate (Cyclic Di-GMP) is a key bacterial second messenger that is implicated in the regulation of many critical processes that include motility, biofilm formation and virulence. Cyclic Di-GMP influences diverse functions through interaction with a range of effectors. Our knowledge of these effectors and their different regulatory actions is far from complete, however. Here we have used an affinity pull-down assay using Cyclic Di-GMP-coupled magnetic beads to identify Cyclic Di-GMP binding proteins in the plant pathogen Xanthomonas campestris pv. campestris (Xcc). This analysis identified XC_3703, a protein of the YajQ family, as a potential Cyclic Di-GMP receptor. Isothermal titration calorimetry showed that the purified XC_3703 protein bound Cyclic Di-GMP with a high affinity (Kd∼2 µM). Mutation of XC_3703 led to reduced virulence of Xcc to plants and alteration in biofilm formation. Yeast two-hybrid and far-western analyses showed that XC_3703 was able to interact with XC_2801, a transcription factor of the LysR family. Mutation of XC_2801 and XC_3703 had partially overlapping effects on the transcriptome of Xcc, and both affected virulence. Electromobility shift assays showed that XC_3703 positively affected the binding of XC_2801 to the promoters of target virulence genes, an effect that was reversed by Cyclic Di-GMP. Genetic and functional analysis of YajQ family members from the human pathogens Pseudomonas aeruginosa and Stenotrophomonas maltophilia showed that they also specifically bound Cyclic Di-GMP and contributed to virulence in model systems. The findings thus identify a new class of Cyclic Di-GMP effector that regulates bacterial virulence.
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Cyclic Di-GMP signalling and the regulation of bacterial virulence.
Microbiology, 2013Co-Authors: Robert P RyanAbstract:Signal transduction pathways involving the second messenger Cyclic Di-GMP [bis-(3′-5′)-Cyclic di-guanosine monophosphate] occur widely in bacteria where they act to link perception of environmental or intracellular cues and signals to specific alterations in cellular function. Such alterations can contribute to bacterial lifestyle transitions including biofilm formation and virulence. The cellular levels of the nucleotide are controlled through the opposing activities of diguanylate cyclases (DGCs) and phosphodiesterases (PDEs). The GGDEF domain of DGCs catalyses the synthesis of Cyclic Di-GMP from GTP, whereas EAL or HD-GYP domains in different classes of PDE catalyse Cyclic Di-GMP degradation to pGpG and GMP. We are now beginning to understand how alterations in Cyclic Di-GMP exert a regulatory action through binding to diverse receptors or effectors that include a small ‘adaptor’ protein domain called PilZ, transcription factors and riboswitches. The regulatory action of enzymically active Cyclic Di-GMP signalling proteins is, however, not restricted to an influence on the level of nucleotide. Here, I will discuss our recent findings that highlight the role that protein–protein interactions involving these signalling proteins have in regulating functions that contribute to bacterial virulence.
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RsmA Regulates Biofilm Formation in Xanthomonas campestris through a Regulatory Network Involving Cyclic Di-GMP and the Clp Transcription Factor
PloS one, 2012Co-Authors: Dong-jie Tang, Jiliang Tang, Yvonne Mccarthy, John Maxwell Dow, Robert P RyanAbstract:Biofilm formation and dispersal in the black rot pathogen Xanthomonas campestris pathovar campestris (Xcc) is influenced by a number of factors. The extracellular mannanase ManA has been implicated in biofilm dispersal whereas biofilm formation requires a putative glycosyl transferase encoded by the xag gene cluster. Previously we demonstrated that the post-transcriptional regulator RsmA exerts a negative regulatory influence on biofilm formation in Xcc. Here we address the mechanisms by which RsmA exerts this action. We show that RsmA binds to the transcripts of three genes encoding GGDEF domain diguanylate cyclases to influence their expression. Accordingly, mutation of rsmA leads to an increase in cellular levels of Cyclic Di-GMP. This effect is associated with a down-regulation of transcription of manA, but an upregulation of xag gene transcription. Mutation of clp, which encodes a Cyclic Di-GMP-responsive transcriptional regulator of the CRP-FNR family, has similar divergent effects on the expression of manA and xag. Nevertheless Clp binding to manA and xag promoters is inhibited by Cyclic Di-GMP. The data support the contention that, in common with other CRP-FNR family members, Clp can act as both an activator and repressor of transcription of different genes to influence biofilm formation as a response to Cyclic Di-GMP.
Christopher M Waters - One of the best experts on this subject based on the ideXlab platform.
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Chemiluminescent sensors for quantitation of the bacterial second messenger Cyclic Di-GMP
Methods in enzymology, 2020Co-Authors: Wyatt A Anderson, Christopher M Waters, Andrew B. Dippel, Michael M. Maiden, Ming C. HammondAbstract:Chemiluminescent biosensors have been developed and broadly applied to mammalian cell systems for studying intracellular signaling networks. For bacteria, biosensors have largely relied on fluorescence-based systems for quantitating signaling molecules, but these designs can encounter issues in complex environments due to their reliance on external illumination. In order to circumvent these issues, we designed the first ratiometric chemiluminescent biosensors for studying a key bacterial second messenger, Cyclic Di-GMP. We have shown recently that these biosensors function both in vitro and in vivo for detecting changes in Cyclic Di-GMP levels. In this chapter, we present a practical and broadly applicable method for high-throughput quantitation of Cyclic Di-GMP in bacterial cell extracts using the high affinity biosensor tVYN-TmΔ that could serve as the "Bradford assay" equivalent for this bacterial signaling molecule.
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Cyclic Di-GMP Regulation of Gene Expression
Microbial Cyclic Di-Nucleotide Signaling, 2020Co-Authors: Meng-lun Hsieh, Deborah M. Hinton, Christopher M WatersAbstract:Cyclic Di-GMP is a nearly ubiquitous bacterial second messenger signaling molecule that links changes in environmental cues to the regulation of a myriad of phenotypes including but not limited to biofilm formation, motility, virulence, and DNA repair. A complex network of Cyclic Di-GMP synthesis and degradation enzymes is present in many bacteria, each of which is hypothesized to respond to a different signal that is integrated into changes in Cyclic Di-GMP levels. Cyclic Di-GMP regulates downstream phenotypes via a variety of different mechanisms including control of transcription initiation via direct interaction with transcription factors, binding to RNA riboswitches to control gene expression post-transcriptionally, or direct interaction with enzymes or protein complexes to allosterically regulate their activity. In this chapter, we will review what is known about Cyclic Di-GMP regulation of gene expression, both transcriptionally and post-transcriptionally, focusing on transcription factors and riboswitches that directly bind to Cyclic Di-GMP.
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Cyclic Di-GMP Positively Regulates DNA Repair in Vibrio cholerae.
Journal of bacteriology, 2018Co-Authors: Nicolas L. Fernandez, Disha Srivastava, Amanda L. Ngouajio, Christopher M WatersAbstract:ABSTRACT In Vibrio cholerae, high intracellular Cyclic Di-GMP (c-Di-GMP) concentration are associated with a biofilm lifestyle, while low intracellular c-Di-GMP concentrations are associated with a motile lifestyle. c-Di-GMP also regulates other behaviors, such as acetoin production and type II secretion; however, the extent of phenotypes regulated by c-Di-GMP is not fully understood. We recently determined that the sequence upstream of the DNA repair gene encoding 3-methyladenine glycosylase (tag) was positively induced by c-Di-GMP, suggesting that this signaling system might impact DNA repair pathways. We identified a DNA region upstream of tag that is required for transcriptional induction by c-Di-GMP. We further showed that c-Di-GMP induction of tag expression was dependent on the c-Di-GMP-dependent biofilm regulators VpsT and VpsR. In vitro binding assays and heterologous host expression studies show that VpsT acts directly at the tag promoter in response to c-Di-GMP to induce tag expression. Last, we determined that strains with high c-Di-GMP concentrations are more tolerant of the DNA-damaging agent methyl methanesulfonate. Our results indicate that the regulatory network of c-Di-GMP in V. cholerae extends beyond biofilm formation and motility to regulate DNA repair through the VpsR/VpsT c-Di-GMP-dependent cascade. IMPORTANCEVibrio cholerae is a prominent human pathogen that is currently causing a pandemic outbreak in Haiti, Yemen, and Ethiopia. The second messenger molecule Cyclic Di-GMP (c-Di-GMP) mediates the transitions in V. cholerae between a sessile biofilm-forming state and a motile lifestyle, both of which are important during V. cholerae environmental persistence and human infections. Here, we report that in V. cholerae c-Di-GMP also controls DNA repair. We elucidate the regulatory pathway by which c-Di-GMP increases DNA repair, allowing this bacterium to tolerate high concentrations of mutagens at high intracellular levels of c-Di-GMP. Our work suggests that DNA repair and biofilm formation may be linked in V. cholerae.
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Shining the Light on Cyclic Di-GMP Dark Matter.
Journal of bacteriology, 2018Co-Authors: Christopher M WatersAbstract:ABSTRACT Bacterial Cyclic Di-GMP signaling networks often consist of dozens of components, and the majority of these components have no observable function. Dahlstrom et al. (J. Bacteriol. 200:e00703-17, 2018, https://doi.org/10.1128/JB.00703-17) explored the function of every component of the Pseudomonas fluorescens Cyclic Di-GMP network under 188 different growth conditions and identified activities for 80% of the network. They further demonstrated that multiple mechanisms function in tandem to control the activity of the network in different environments.
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Cyclic Di-GMP and VpsR Induce the Expression of Type II Secretion in Vibrio cholerae.
Journal of bacteriology, 2017Co-Authors: Rudolph E. Sloup, Geoffrey B Severin, Ashley E. Konal, Michelle L. Korir, Mira M. Bagdasarian, Christopher M WatersAbstract:Vibrio cholerae is a human pathogen that alternates between growth in environmental reservoirs and infection of human hosts, causing severe diarrhea. The second messenger Cyclic Di-GMP (c-Di-GMP) mediates this transition by controlling a wide range of functions, such as biofilms, virulence, and motility. Here, we report that c-Di-GMP induces expression of the extracellular protein secretion (eps) gene cluster, which encodes the type II secretion system (T2SS) in V. cholerae Analysis of the eps genes confirmed the presence of two promoters located upstream of epsC, the first gene in the operon, one of which is induced by c-Di-GMP. This induction is directly mediated by the c-Di-GMP-binding transcriptional activator VpsR. Increased expression of the eps operon did not impact secretion of extracellular toxin or biofilm formation but did increase expression of the pseudopilin protein EpsG on the cell surface.IMPORTANCE Type II secretion systems (T2SSs) are the primary molecular machines by which Gram-negative bacteria secrete proteins and protein complexes that are folded and assembled in the periplasm. The substrates of T2SSs include extracellular factors, such as proteases and toxins. Here, we show that the widely conserved second messenger Cyclic Di-GMP (c-Di-GMP) upregulates expression of the eps genes encoding the T2SS in the pathogen V. cholerae via the c-Di-GMP-dependent transcription factor VpsR.
Ute Römling - One of the best experts on this subject based on the ideXlab platform.
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A Cyclic Di-GMP Network Is Present in Gram-Positive Streptococcus and Gram-Negative Proteus Species.
ACS Infectious Diseases, 2020Co-Authors: Ying Liu, Changhan Lee, Janja Trček, Heike Bähre, Rey-ting Guo, Chun-chi Chen, Alexey Chernobrovkin, Roman A. Zubarev, Ute RömlingAbstract:The ubiquitous Cyclic Di-GMP (c-Di-GMP) network is highly redundant with numerous GGDEF domain proteins as diguanylate cyclases and EAL domain proteins as c-Di-GMP specific phosphodiesterases compr...
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A Cyclic Di-GMP Network Is Present in Gram-Positive Streptococcus and Gram-Negative Proteus Species
2020Co-Authors: Ying Liu, Changhan Lee, Janja Trček, Heike Bähre, Rey-ting Guo, Chun-chi Chen, Alexey Chernobrovkin, Roman Zubarev, Ute RömlingAbstract:Cyclic Di-GMP is a ubiquitous second messenger in bacteria. This work describes the occurrence of a Cyclic Di-GMP signaling network in Gram-positive <i>Streptococcus </i>species and Gram-negative <i>Proteus</i>. After identification of candidate diguanylate cyclases by homology search in the respective species, the open reading frames were cloned and proteins expressed. Production of Cyclic Di-GMP was demonstrated by riboswitch assays, detection of Cyclic Di-GMP in cell lysates by MALDI-FTMS and in cell extracts by standard LC-MS/MS. Expression of the diguanylate cyclases in the heterologous host Salmonella typhimurium showed the expected physiological activity, namely up regulation of biofilm formation and down regulation of motility. The co-localisation of both sole diguanylate cyclases with cellulose or cellulose-like synthases indicates exopolysaccharide biosynthesis to be a conserved trait of Cyclic Di-GMP signaling.
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Discovery of the Second Messenger Cyclic Di-GMP.
Methods in molecular biology (Clifton N.J.), 2017Co-Authors: Ute Römling, Michael Y. GalperinAbstract:The nearly ubiquitous bacterial second messenger Cyclic Di-GMP is involved in a multitude of fundamental physiological processes such as sessility/motility transition and the switch between the acute and chronic infection status, combined with cell cycle control. The discovery of Cyclic Di-GMP, though, has been an example par excellence of scientific serendipity. We recapitulate here its years-long discovery process as an activator of the cellulose synthase of the environmental bacterium Komagataeibacter xylinus and its consequences for follow-up research. Indeed, the discovery of Cyclic Di-GMP as a ubiquitous second messenger contributed to the change in perception of bacteria as simple unicellular organisms just randomly building-up multicellular communities. Subsequently, Cyclic Di-GMP also paved the way to the identification of other pro- and eukaryotic Cyclic dinucleotide second messengers.
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Cyclic di gmp the first 25 years of a universal bacterial second messenger
Microbiology and Molecular Biology Reviews, 2013Co-Authors: Ute Römling, Michael Y. Galperin, Mark GomelskyAbstract:SUMMARY Twenty-five years have passed since the discovery of Cyclic dimeric (3′→5′) GMP (Cyclic Di-GMP or c-Di-GMP). From the relative obscurity of an allosteric activator of a bacterial cellulose synthase, c-Di-GMP has emerged as one of the most common and important bacterial second messengers. Cyclic Di-GMP has been shown to regulate biofilm formation, motility, virulence, the cell cycle, differentiation, and other processes. Most c-Di-GMP-dependent signaling pathways control the ability of bacteria to interact with abiotic surfaces or with other bacterial and eukaryotic cells. Cyclic Di-GMP plays key roles in lifestyle changes of many bacteria, including transition from the motile to the sessile state, which aids in the establishment of multicellular biofilm communities, and from the virulent state in acute infections to the less virulent but more resilient state characteristic of chronic infectious diseases. From a practical standpoint, modulating c-Di-GMP signaling pathways in bacteria could represent a new way of controlling formation and dispersal of biofilms in medical and industrial settings. Cyclic Di-GMP participates in interkingdom signaling. It is recognized by mammalian immune systems as a uniquely bacterial molecule and therefore is considered a promising vaccine adjuvant. The purpose of this review is not to overview the whole body of data in the burgeoning field of c-Di-GMP-dependent signaling. Instead, we provide a historic perspective on the development of the field, emphasize common trends, and illustrate them with the best available examples. We also identify unresolved questions and highlight new directions in c-Di-GMP research that will give us a deeper understanding of this truly universal bacterial second messenger.
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Cyclic Di-GMP, an established secondary messenger still speeding up.
Environmental microbiology, 2011Co-Authors: Ute RömlingAbstract:Summary The secondary messenger Cyclic Di-GMP coordinately regulates the transition between motility/sessility/virulence in bacterial populations and upon adaptation to novel habitats. Thereby, multiple independent regulatory circuits regulate a diversity of targets. This specific output response is surprising considering the diverse physiological processes regulated by this signalling molecule, which range from transcription to proteolysis and clearly demonstrates the presence of sophisticated developmental programmes in these so-called simple organisms.
Ming C. Hammond - One of the best experts on this subject based on the ideXlab platform.
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Chemiluminescent sensors for quantitation of the bacterial second messenger Cyclic Di-GMP
Methods in enzymology, 2020Co-Authors: Wyatt A Anderson, Christopher M Waters, Andrew B. Dippel, Michael M. Maiden, Ming C. HammondAbstract:Chemiluminescent biosensors have been developed and broadly applied to mammalian cell systems for studying intracellular signaling networks. For bacteria, biosensors have largely relied on fluorescence-based systems for quantitating signaling molecules, but these designs can encounter issues in complex environments due to their reliance on external illumination. In order to circumvent these issues, we designed the first ratiometric chemiluminescent biosensors for studying a key bacterial second messenger, Cyclic Di-GMP. We have shown recently that these biosensors function both in vitro and in vivo for detecting changes in Cyclic Di-GMP levels. In this chapter, we present a practical and broadly applicable method for high-throughput quantitation of Cyclic Di-GMP in bacterial cell extracts using the high affinity biosensor tVYN-TmΔ that could serve as the "Bradford assay" equivalent for this bacterial signaling molecule.
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Cyclic Di-GMP Signaling Gone Astray: Cyclic GAMP Signaling via Hypr GGDEF and HD-GYP Enzymes
Microbial Cyclic Di-Nucleotide Signaling, 2020Co-Authors: Todd A. Wright, Andrew B. Dippel, Ming C. HammondAbstract:GGDEF domain and HD-GYP enzymes are classically associated with Cyclic Di-GMP signaling. Here we describe our current knowledge of variants of these enzyme classes that instead are involved in Cyclic GMP-AMP (cGAMP) signaling, including their discovery, recent elucidation of signature active site residues, specific phenotypes, and regulatory mechanisms. Furthermore, we highlight our development of in vivo activity assays using riboswitch-based fluorescent biosensors that enabled the discovery and validation of these divergent signaling enzymes.
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Chemiluminescent Biosensors for Detection of Second Messenger Cyclic Di-GMP
ACS chemical biology, 2018Co-Authors: Andrew B. Dippel, Wyatt A Anderson, Robert S Evans, Samuel Deutsch, Ming C. HammondAbstract:Bacteria colonize highly diverse and complex environments, from gastrointestinal tracts to soil and plant surfaces. This colonization process is controlled in part by the intracellular signal Cyclic Di-GMP, which regulates bacterial motility and biofilm formation. To interrogate Cyclic Di-GMP signaling networks, a variety of fluorescent biosensors for live cell imaging of Cyclic Di-GMP have been developed. However, the need for external illumination precludes the use of these tools for imaging bacteria in their natural environments, including in deep tissues of whole organisms and in samples that are highly autofluorescent or photosensitive. The need for genetic encoding also complicates the analysis of clinical isolates and environmental samples. Toward expanding the study of bacterial signaling to these systems, we have developed the first chemiluminescent biosensors for Cyclic Di-GMP. The biosensor design combines the complementation of split luciferase (CSL) and bioluminescence resonance energy transfer (BRET) approaches. Furthermore, we developed a lysate-based assay for biosensor activity that enabled reliable high-throughput screening of a phylogenetic library of 92 biosensor variants. The screen identified biosensors with very large signal changes (∼40- and 90-fold) as well as biosensors with high affinities for Cyclic Di-GMP ( KD < 50 nM). These chemiluminescent biosensors then were applied to measure Cyclic Di-GMP levels in E. coli. The cellular experiments revealed an unexpected challenge for chemiluminescent imaging in Gram negative bacteria but showed promising application in lysates. Taken together, this work establishes the first chemiluminescent biosensors for studying Cyclic Di-GMP signaling and provides a foundation for using these biosensors in more complex systems.
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In Vivo Biochemistry: Single-Cell Dynamics of Cyclic Di-GMP in Escherichia coli in Response to Zinc Overload.
Biochemistry, 2017Co-Authors: Jongchan Yeo, Andrew B. Dippel, Xin C. Wang, Ming C. HammondAbstract:Intracellular signaling enzymes drive critical changes in cellular physiology and gene expression, but their endogenous activities in vivo remain highly challenging to study in real time and for individual cells. Here we show that flow cytometry can be performed in complex media to monitor single-cell population distributions and dynamics of Cyclic Di-GMP signaling, which controls the bacterial colonization program. These in vivo biochemistry experiments are enabled by our second-generation RNA-based fluorescent (RBF) biosensors, which exhibit high fluorescence turn-on in response to Cyclic Di-GMP. Specifically, we demonstrate that intracellular levels of Cyclic Di-GMP in Escherichia coli are repressed with excess zinc, but not with other divalent metals. Furthermore, in both flow cytometry and fluorescence microscopy setups, we monitor the dynamic increase in cellular Cyclic Di-GMP levels upon zinc depletion and show that this response is due to de-repression of the endogenous diguanylate cyclase DgcZ. I...
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Next-generation RNA-based fluorescent biosensors enable anaerobic detection of Cyclic Di-GMP
Nucleic acids research, 2016Co-Authors: Xin C. Wang, Stephen C Wilson, Ming C. HammondAbstract:Bacteria occupy a diverse set of environmental niches with differing oxygen availability. Anaerobic environments such as mammalian digestive tracts and industrial reactors harbor an abundance of both obligate and facultative anaerobes, many of which play significant roles in human health and biomanufacturing. Studying bacterial function under partial or fully anaerobic conditions, however, is challenging given the paucity of suitable live-cell imaging tools. Here, we introduce a series of RNA-based fluorescent biosensors that respond selectively to Cyclic Di-GMP, an intracellular bacterial second messenger that controls cellular motility and biofilm formation. We demonstrate the utility of these biosensors in vivo under both aerobic and anaerobic conditions, and we show that biosensor expression does not interfere with the native motility phenotype. Together, our results attest to the effectiveness and versatility of RNA-based fluorescent biosensors, priming further development and application of these and other analogous sensors to study host-microbial and microbial-microbial interactions through small molecule signals.
Yvonne Fouhy - One of the best experts on this subject based on the ideXlab platform.
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Cyclic di gmp signalling in the virulence and environmental adaptation of xanthomonas campestris
Molecular Microbiology, 2007Co-Authors: Robert P Ryan, Yvonne Fouhy, Jean F Lucey, Bole Jiang, Yongqiang He, Jiaxun Feng, Jiliang TangAbstract:Cyclic Di-GMP is a second messenger with a role in regulation of a range of cellular functions in diverse bacteria including the virulence of pathogens. Cellular levels of Cyclic Di-GMP are controlled through synthesis, catalysed by the GGDEF protein domain, and degradation by EAL or HD-GYP domains. Here we report a comprehensive study of Cyclic Di-GMP signalling in bacterial disease in which we examine the contribution of all proteins with GGDEF, EAL or HD-GYP domains to virulence and virulence factor production in the phytopathogen Xanthomonas campestris pathovar campestris (Xcc). Genes with significant roles in virulence to plants included those encoding proteins whose probable function is in Cyclic-Di-GMP synthesis as well as others (including the HD-GYP domain regulator RpfG) implicated in Cyclic Di-GMP degradation. Furthermore, RpfG controlled expression of a subset of these genes. A partially overlapping set of elements controlled the production of virulence factors in vitro. Other GGDEF-EAL domain proteins had no effect on virulence factor synthesis but did influence motility. These findings indicate the existence of a regulatory network that may allow Xcc to integrate information from diverse environmental inputs to modulate virulence factor synthesis as well as of Cyclic Di-GMP signalling systems dedicated to other specific tasks.
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Cyclic di gmp signaling in bacteria recent advances and new puzzles
Journal of Bacteriology, 2006Co-Authors: Robert P Ryan, Yvonne Fouhy, Jean F Lucey, Maxwell J DowAbstract:Cyclic Di-GMP \[bis-(3′-5′)-Cyclic Di-GMP\] (Fig. [1][1]) is a novel second messenger in bacteria that was first described as an allosteric activator of cellulose synthase in Gluconacetobacter xylinus ([49][2]). It is now established that this nucleotide is almost ubiquitous in bacteria, where
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The HD-GYP domain, Cyclic Di-GMP signaling, and bacterial virulence to plants.
Molecular Plant-microbe Interactions, 2006Co-Authors: Yvonne Fouhy, Jean F Lucey, Robert P RyanAbstract:Cyclic Di-GMP is an almost ubiquitous second messenger in bacteria that was first described as an allosteric activator of cellulose synthase but is now known to regulate a range of functions, including virulence in human and animal pathogens. Two protein domains, GGDEF and EAL, are implicated in the synthesis and degradation, respectively, of Cyclic Di-GMP. These domains are widely distributed in bacteria, including plant pathogens. The majority of proteins with GGDEF and EAL domains contain additional signal input domains, suggesting that their activities are responsive to environmental cues. Recent studies have demonstrated that a third domain, HD-GYP, is also active in Cyclic Di-GMP degradation. In the plant pathogen Xanthomonas campestris pv. campestris, a two-component signal transduction system comprising the HD-GYP domain regulatory protein RpfG and cognate sensor RpfC positively controls virulence. The signals recognized by RpfC may include the cell-cell signal DSF, which also acts to regulate virulence in X. campestris pv. campestris. Here, we review these recent advances in our understanding of Cyclic Di-GMP signaling with particular reference to one or more roles in the bacterial pathogenesis of plants.
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Cell-cell signaling, Cyclic Di-GMP turnover and regulation of virulence in Xanthomonas campestris.
Research in microbiology, 2006Co-Authors: Yvonne Fouhy, Robert P Ryan, Jean F Lucey, J. Maxwell DowAbstract:The synthesis of virulence factors in the plant pathogen Xanthomonas campestris pathovar campestris is regulated by cell-cell signaling mediated by a diffusible signal factor (DSF), and by the RpfC/RpfG two-component regulatory system. Recent findings have indicated that the perception of the DSF signal requires the RpfC sensor and is linked to the degradation of the intracellular second messenger Cyclic Di-GMP by the HD-GYP domain regulator RpfG.
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cell cell signaling in xanthomonas campestris involves an hd gyp domain protein that functions in Cyclic di gmp turnover
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Robert P Ryan, Yvonne Fouhy, Jean F Lucey, Lisa Crossman, Stephen Spiro, Ya Wen He, Lian-hui Zhang, Stephan Heeb, Miguel Cámara, Paul WilliamsAbstract:HD-GYP is a protein domain of unknown biochemical function implicated in bacterial signaling and regulation. In the plant pathogen Xanthomonas campestris pv. campestris, the synthesis of virulence factors and dispersal of biofilms are positively controlled by a two-component signal transduction system comprising the HD-GYP domain regulatory protein RpfG and cognate sensor RpfC and by cell–cell signaling mediated by the diffusible signal molecule DSF (diffusible signal factor). The RpfG/RpfC two-component system has been implicated in DSF perception and signal transduction. Here we show that the role of RpfG is to degrade the unusual nucleotide Cyclic Di-GMP, an activity associated with the HD-GYP domain. Mutation of the conserved H and D residues of the isolated HD-GYP domain resulted in loss of both the enzymatic activity against Cyclic Di-GMP and the regulatory activity in virulence factor synthesis. Two other protein domains, GGDEF and EAL, are already implicated in the synthesis and degradation respectively of Cyclic Di-GMP. As with GGDEF and EAL domains, the HD-GYP domain is widely distributed in free-living bacteria and occurs in plant and animal pathogens, as well as beneficial symbionts and organisms associated with a range of environmental niches. Identification of the role of the HD-GYP domain thus increases our understanding of a signaling network whose importance to the lifestyle of diverse bacteria is now emerging.
