A fructose/H+ symporter controlled by a LacI-type regulator promotes survival of pandemic Vibrio cholerae in seawater

AbstractThe bacterium Vibrio cholerae can colonize the human intestine and cause cholera, but spends much of its life cycle in seawater. The pathogen must adapt to substantial environmental changes when moving between seawater and the human intestine, including different availability of carbon sources such as fructose. Here, we use in vitro experiments as well as mouse intestinal colonization assays to study the mechanisms used by pandemic V. cholerae to adapt to these environmental changes. We show that a LacI-type regulator (FruI) and a fructose/H+ symporter (FruT) are important for fructose uptake at low fructose concentrations, as those found in seawater. FruT is downregulated by FruI, which is upregulated when O2 concentrations are low (as in the intestine) by ArcAB, a two-component system known to respond to changes in oxygen levels. As a result, the bacteria predominantly use FruT for fructose uptake under seawater conditions (low fructose, high O2), and use a known fructose phosphotransferase system (PTS, Fpr) for fructose uptake under conditions found in the intestine. PTS activity leads to reduced levels of intracellular cAMP, which in turn upregulate virulence genes. Our results indicate that the FruT/FruI system may be important for survival of pandemic V. cholerae in seawater.

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The Vibrio cholerae VarS/VarA two-component system controls the expression of virulence proteins through ToxT regulation

Microbiology ◽

10.1099/mic.0.043737-0 ◽

2011 ◽

Vol 157 (5) ◽

pp. 1466-1473 ◽

Cited By ~ 19

Author(s):

Jeyoun Jang ◽

Kyung-Tae Jung ◽

Jungchan Park ◽

Cheon-Kwon Yoo ◽

Gi-Eun Rhie

Keyword(s):

Vibrio Cholerae ◽

Environmental Changes ◽

Transcription Activator ◽

Two Component System ◽

Component System ◽

Virulence Proteins ◽

Two Component ◽

Virulence Protein ◽

El Tor

Although the conditions for inducing virulence protein expression in vitro are different, both classical and El Tor biotypes of Vibrio cholerae have been reported to regulate the expression of virulence proteins such as cholera toxin (CT) and toxin-coregulated pili (Tcp) through the ToxR/S/T system. The transcription activator ToxR responds to environmental stimuli such as pH and temperature and activates the second transcriptional regulator ToxT, which upregulates expression of virulence proteins. In addition to the ToxR/S/T signalling system, V. cholerae has been proposed to utilize another two-component system VarS/VarA to modulate expression of virulence genes. Previous study has shown that VarA of the VarS/VarA system is involved in the regulation of virulence proteins in the classical V. cholerae O395 strain; however, no further analysis was performed concerning VarS. In this study, we constructed varS mutants derived from the classical O395 and El Tor C6706 strains and demonstrated that VarS is also involved in the expression of the virulence proteins CT and Tcp from the V. cholerae classical and El Tor strains. This expression is through regulation of ToxT expression in response to environmental changes due to different toxin-inducing conditions.

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Sugar-mediated regulation of a c-di-GMP phosphodiesterase in Vibrio cholerae

Nature Communications ◽

10.1038/s41467-019-13353-5 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Kyoo Heo ◽

Young-Ha Park ◽

Kyung-Ah Lee ◽

Joonwon Kim ◽

Hyeong-In Ham ◽

...

Keyword(s):

Vibrio Cholerae ◽

Biofilm Formation ◽

Carbon Sources ◽

Phosphotransferase System ◽

Host Colonization ◽

Host Immune Responses ◽

Gut Colonization ◽

Host Diet ◽

Underlying Mechanisms ◽

Cyclic Dinucleotide

AbstractBiofilm formation protects bacteria from stresses including antibiotics and host immune responses. Carbon sources can modulate biofilm formation and host colonization in Vibrio cholerae, but the underlying mechanisms remain unclear. Here, we show that EIIAGlc, a component of the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS), regulates the intracellular concentration of the cyclic dinucleotide c-di-GMP, and thus biofilm formation. The availability of preferred sugars such as glucose affects EIIAGlc phosphorylation state, which in turn modulates the interaction of EIIAGlc with a c-di-GMP phosphodiesterase (hereafter referred to as PdeS). In a Drosophila model of V. cholerae infection, sugars in the host diet regulate gut colonization in a manner dependent on the PdeS-EIIAGlc interaction. Our results shed light into the mechanisms by which some nutrients regulate biofilm formation and host colonization.

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Role of Vibrio cholerae O139 Surface Polysaccharides in Intestinal Colonization

Infection and Immunity ◽

10.1128/iai.70.11.5990-5996.2002 ◽

2002 ◽

Vol 70 (11) ◽

pp. 5990-5996 ◽

Cited By ~ 42

Author(s):

Jutta Nesper ◽

Stefan Schild ◽

Crystal M. Lauriano ◽

Anita Kraiss ◽

Karl E. Klose ◽

...

Keyword(s):

Vibrio Cholerae ◽

Capsular Polysaccharide ◽

Genetically Engineered ◽

Side Chain ◽

Intestinal Colonization ◽

Core Oligosaccharide ◽

Infant Mouse ◽

Surface Polysaccharides

ABSTRACT Since the first occurrence of O139 Vibrio cholerae as a cause of cholera epidemics, this serogroup has been investigated intensively, and it has been found that its pathogenicity is comparable to that of O1 El Tor strains. O139 isolates express a thin capsule, composed of a polymer of repeating units structurally identical to the lipopolysaccharide (LPS) O side chain. In this study, we investigated the role of LPS O side chain and capsular polysaccharide (CPS) in intestinal colonization by with genetically engineered mutants. We constructed CPS-negative, CPS/LPS O side chain-negative, and CPS-positive/LPS O side chain-negative mutants. Furthermore, we constructed two mutants with defects in LPS core oligosaccharide (OS) assembly. Loss of LPS O side chain or CPS resulted in a ≈30-fold reduction in colonization of the infant mouse small intestine, indicating that the presence of both LPS O side chain and CPS is important during the colonization process. The strain lacking both CPS and LPS O side chain and a CPS-positive, LPS O side chain-negative core OS mutant were both essentially unable to colonize. To characterize the role of surface polysaccharides in survival in the host intestine, resistance to several antimicrobial substances was investigated in vitro. These investigations revealed that the presence of CPS protects the cell against attack of the complement system and that an intact core OS is necessary for survival in the presence of bile.

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The Regulatory Cascade That Activates the Hrp Regulon in Erwinia herbicola pv. gypsophilae

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2003.16.3.249 ◽

2003 ◽

Vol 16 (3) ◽

pp. 249-260 ◽

Cited By ~ 40

Author(s):

R. Nizan-Koren ◽

S. Manulis ◽

H. Mor ◽

N. M. Iraki ◽

I. Barash

Keyword(s):

Transcriptional Activity ◽

Virulence Genes ◽

Regulatory Genes ◽

Site Directed Mutagenesis ◽

In Planta ◽

Two Component System ◽

Erwinia Herbicola ◽

Basal Expression ◽

Regulatory Cascade

The pathogenicity of Erwinia herbicola pv. gypsophilae (Ehg) is dependent on a plasmid (pPATHEhg) that harbors the hrp gene cluster and additional virulence genes. The hrp regulatory cascade of Ehg comprises an hrpXY operon encoding a two-component system; hrpS encoding a transcriptional factor of the NtrC family and hrpL encoding an alternative sigma factor. Results obtained suggest the following signal transduction model for activating the Hrp regulon: phosphorylated HrpY activates hrpS, HrpS activates hrpL, and HrpL activates genes containing “hrp box” promoter. This model was supported by studies on the effects of mutations in the regulatory genes on pathogenicity and complementation analysis. Nonpolar mutations in hrpX did not affect virulence or transcription of downstream genes. Site-directed mutagenesis of the conserved aspartate 57 in HrpY suggested that its phosphorylation is crucial for activating the hrp regulatory cascade. Studies on the effects of mutations in the hrp regulatory genes on transcriptional activity of downstream genes or of their isolated promoters in planta showed dependency of hrpS expression on active HrpY, of hrpL expression on active HrpS, and of hrpN or hrpJ expression on active HrpL. These results were also partially supported by overexpression of regulatory genes under in vitro conditions. The hrpXY is constitutively expressed with high basal levels under repressive conditions, in contrast to hrpS and hrpL, which exhibit low basal expression levels and are environmentally regulated.

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A Vibrio cholerae LysR Homolog, AphB, Cooperates with AphA at the tcpPH Promoter To Activate Expression of the ToxR Virulence Cascade

Journal of Bacteriology ◽

10.1128/jb.181.14.4250-4256.1999 ◽

1999 ◽

Vol 181 (14) ◽

pp. 4250-4256 ◽

Cited By ~ 133

Author(s):

Gabriela Kovacikova ◽

Karen Skorupski

Keyword(s):

Vibrio Cholerae ◽

Virulence Genes ◽

Virulence Gene ◽

Growth Conditions ◽

Culture Conditions ◽

Virulence Gene Expression ◽

Environmental Stimuli ◽

High Level ◽

El Tor

ABSTRACT We describe here a new member of the LysR family of transcriptional regulators, AphB, which is required for activation of the Vibrio cholerae ToxR virulence cascade. AphB activates the transcription of the tcpPH operon in response to environmental stimuli, and this process requires cooperation with a second protein, AphA. The expression of neither aphA or aphB is strongly regulated by environmental stimuli, raising the possibility that the activities of the proteins themselves may be influenced under various conditions. Strains of the El Tor biotype of V. choleraetypically exhibit lower expression of ToxR-regulated virulence genes in vitro than classical strains and require specialized culture conditions (AKI medium) to induce high-level expression. We show here that expression of aphB from the tac promoter in El Tor biotype strains dramatically increases virulence gene expression to levels similar to those observed in classical strains under all growth conditions examined. These results suggest that AphB plays a role in the differential regulation of virulence genes between the two disease-causing biotypes.

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Differential Transcription of the tcpPHOperon Confers Biotype-Specific Control of the Vibrio cholerae ToxR Virulence Regulon

Infection and Immunity ◽

10.1128/iai.67.10.5117-5123.1999 ◽

1999 ◽

Vol 67 (10) ◽

pp. 5117-5123 ◽

Cited By ~ 35

Author(s):

Yvette M. Murley ◽

Patricia A. Carroll ◽

Karen Skorupski ◽

Ronald K. Taylor ◽

Stephen B. Calderwood

Keyword(s):

Gene Expression ◽

Vibrio Cholerae ◽

Virulence Genes ◽

Virulence Gene ◽

Environmental Signals ◽

Virulence Gene Expression ◽

Response To Temperature ◽

El Tor ◽

Differential Transcription

ABSTRACT Epidemic strains of Vibrio cholerae O1 are divided into two biotypes, classical and El Tor. In both biotypes, regulation of virulence gene expression depends on a cascade in which ToxR activates expression of ToxT, and ToxT activates expression of cholera toxin and other virulence genes. In the classical biotype, maximal expression of this ToxR regulon in vitro occurs at 30°C at pH 6.5 (ToxR-inducing conditions), whereas in the El Tor biotype, production of these virulence genes only occurs under very limited conditions and not in response to temperature and pH; this difference between biotypes is mediated at the level of toxT transcription. In the classical biotype, two other proteins, TcpP and TcpH, are needed for maximal toxT transcription. Transcription oftcpPH in the classical biotype is regulated by pH and temperature independently of ToxR or ToxT, suggesting that TcpP and TcpH couple environmental signals to transcription of toxT. In this study, we show a near absence of tcpPH message in the El Tor biotype under ToxR-inducing conditions of temperature and pH. However, once expressed, El Tor TcpP and TcpH appear to be as effective as classical TcpP and TcpH in activating toxTtranscription. These results suggest that differences in regulation of virulence gene expression between the biotypes of V. cholerae primarily result from differences in expression oftcpPH message in response to environmental signals. We present an updated model for control of the ToxR virulence regulon inV. cholerae.

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Vibrio cholerae Requires rpoS for Efficient Intestinal Colonization

Infection and Immunity ◽

10.1128/iai.68.12.6691-6696.2000 ◽

2000 ◽

Vol 68 (12) ◽

pp. 6691-6696 ◽

Cited By ~ 38

Author(s):

D. Scott Merrell ◽

Anna D. Tischler ◽

Sang Ho Lee ◽

Andrew Camilli

Keyword(s):

Vibrio Cholerae ◽

Diarrheal Disease ◽

Detectable Effect ◽

Intestinal Colonization ◽

Insertional Inactivation ◽

Intestinal Pathogen ◽

Colonization Ability ◽

Mutant Phenotypes

ABSTRACT Vibrio cholerae is a facultative intestinal pathogen that lives in aquatic environments, often in association with planktonic species. In the suckling mouse, oral inoculation withV. cholerae leads to intestinal colonization and symptoms of diarrheal disease. Results reported here indicate a role for the alternative sigma factor, RpoS, in intestinal colonization in this model of cholera. We constructed within rpoS multiple independent mutations which consistently resulted in a fivefold decrease in colonization ability as assessed by competition assays. These mutations had no detectable effect on the in vitro growth ofV. cholerae in a rich medium. The occurrence of spontaneous suppressor mutations potentially required for viability ofrpoS strains was ruled out by determination of the frequency of insertional inactivation of rpoS in comparison to two other nonessential loci. Finally, both the in vitro and in vivo mutant phenotypes of rpoS strains were fully complemented by providing rpoS in trans or by allelic reversion, indicating that the observed decrease in colonization fitness was indeed due to the loss of functional RpoS.

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Utilization of carbon sources by clinical isolates ofAeromonas

Canadian Journal of Microbiology ◽

10.1139/cjm-2016-0526 ◽

2017 ◽

Vol 63 (4) ◽

pp. 359-364 ◽

Cited By ~ 1

Author(s):

Karoline C. Prediger ◽

Monica Surek ◽

Cibelle B. Dallagassa ◽

Flávia E.A. Assis ◽

Mario S. Piantavini ◽

...

Keyword(s):

Amino Acids ◽

Pathogenic Bacteria ◽

Carbon Sources ◽

Aquatic Organisms ◽

Wound Infections ◽

Human Intestine ◽

Common Condition ◽

Intestinal Mucin ◽

Carbon Substrates

Bacteria in the genus Aeromonas are primarily aquatic organisms; however, some species can cause diseases in humans, ranging from wound infections to septicemia, of which diarrhea is the most common condition. The ability to use a variety of carbon substrates is advantageous for pathogenic bacteria. Therefore, we used Biolog GN2 microplates to analyze the ability of 103 clinical, predominantly diarrheal, isolates of Aeromonas to use various carbon sources, and we verified whether, among the substrates metabolized by these strains, there were some endogenous to the human intestine. The results indicate that Aeromonas present great diversity in the utilization of carbon sources, and that they preferentially use carbohydrates and amino acids as carbon sources. Among the carbon sources metabolized by Aeromonas in vitro, some were found to be components of intestinal mucin, including aspartic acid, glutamic acid, l-serine, galactose, N-acetyl-glucosamine, and glucose, which were used by all strains tested. Additionally, mannose, d-serine, proline, threonine, and N-acetyl-galactosamine were used by several strains. The potential to metabolize substrates endogenous to the intestine may contribute to Aeromonas’ capacity to grow in and colonize the intestine. We speculate that this may help explain the ability of Aeromonas to cause diarrhea.

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Vibrio cholerae Phosphoenolpyruvate Phosphotransferase System Control of Carbohydrate Transport, Biofilm Formation, and Colonization of the Germfree Mouse Intestine

Infection and Immunity ◽

10.1128/iai.01356-09 ◽

2010 ◽

Vol 78 (4) ◽

pp. 1482-1494 ◽

Cited By ~ 46

Author(s):

Laetitia Houot ◽

Sarah Chang ◽

Cedric Absalon ◽

Paula I. Watnick

Keyword(s):

Vibrio Cholerae ◽

Biofilm Formation ◽

System Control ◽

Cellular Functions ◽

Phosphotransferase System ◽

Germfree Mouse ◽

Abiotic Surfaces ◽

Carbohydrate Transport ◽

Mouse Intestine

ABSTRACT The bacterial phosphoenolpyruvate phosphotransferase system (PTS) is a highly conserved phosphotransfer cascade whose components modulate many cellular functions in response to carbohydrate availability. Here, we further elucidate PTS control of Vibrio cholerae carbohydrate transport and activation of biofilm formation on abiotic surfaces. We then define the role of the PTS in V. cholerae colonization of the adult germfree mouse intestine. We report that V. cholerae colonizes both the small and large intestines of the mouse in a distribution that does not change over the course of a month-long experiment. Because V. cholerae possesses many PTS-independent carbohydrate transporters, the PTS is not essential for bacterial growth in vitro. However, we find that the PTS is essential for colonization of the germfree adult mouse intestine and that this requirement is independent of PTS regulation of biofilm formation. Therefore, competition for PTS substrates may be a dominant force in the success of V. cholerae as an intestinal pathogen. Because the PTS plays a role in colonization of environmental surfaces and the mammalian intestine, we propose that it may be essential to successful transit of V. cholerae through its life cycle of pathogenesis and environmental persistence.

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