Catabolism of mucus components influences motility of Vibrio cholerae in the presence of environmental reservoirs.

Vibrio cholerae O1, the etiological agent of cholera, is a natural inhabitant of aquatic ecosystems. Motility is a critical element for the colonization of both the human host and its environmental reservoirs. In this study, we investigated the molecular mechanisms underlying the chemotactic response of V.

Identification of a Small Molecule Activator for AphB, a LysR-Type Virulence Transcriptional Regulator in Vibrio cholerae.

AphB is a LysR-type transcriptional regulator (LTTR) that cooperates with a second transcriptional activator, AphA, at the tcpPH promoter to initiate expression of the virulence cascade in Vibrio cholerae. Because it is not yet known whether AphB responds to a natural ligand in V. cholerae that influences its ability to activate transcription, we used a computational approach to identify small molecules that influence its activity.

Bile salts and alkaline pH reciprocally modulate the interaction between the periplasmic domains of Vibrio cholerae ToxR and ToxS.

ToxR is a transmembrane transcription factor that is essential for virulence gene expression and human colonization by Vibrio cholerae. ToxR requires its operon partner ToxS, a periplasmic integral membrane protein, for full activity. These two proteins are thought to interact through their respective periplasmic domains, ToxRp and ToxSp.

Production of putative enhanced oral cholera vaccine strains that express toxin-coregulated pilus.

The use of whole cell killed (WCK) oral cholera vaccines is an important strategy for cholera prevention in endemic areas. To overcome current vaccine limitations, we engineered strains of V. cholerae to be non-toxigenic and to express the protective protein colonization factor, toxin-coregulated pilus (TCP), under scale-up conditions potentially amenable to vaccine production.

A new class of inhibitors of the AraC family virulence regulator Vibrio cholerae ToxT.

Vibrio cholerae is responsible for the diarrheal disease cholera that infects millions of people worldwide. While vaccines protecting against cholera exist, and oral rehydration therapy is an effective treatment method, the disease will remain a global health threat until long-term solutions such as improved sanitation and access to clean water become widely available. Because of this, there is a pressing need for potent therapeutics that can either mitigate cholera symptoms, or act prophylactically to prevent the virulent effects of a cholera infection.

Architecture of the Vibrio cholerae toxin-coregulated pilus machine revealed by electron cryotomography.

Type IV pili (T4P) are filamentous appendages found on many Bacteria and Archaea. They are helical fibres of pilin proteins assembled by a multi-component macromolecular machine we call the basal body. Based on pilin features, T4P are classified into type IVa pili (T4aP) and type IVb pili (T4bP).

The Fatty Acid Regulator FadR Influences the Expression of the Virulence Cascade in the El Tor Biotype of Vibrio cholerae by Modulating the Levels of ToxT via Two Different Mechanisms.

FadR is a master regulator of fatty acid (FA) metabolism that coordinates the pathways of FA degradation and biosynthesis in enteric bacteria. We show here that a Δ mutation in the El Tor biotype of prevents the expression of the virulence cascade by influencing both the transcription and the posttranslational regulation of the master virulence regulator ToxT. FadR is a transcriptional regulator that represses the expression of genes involved in FA degradation, activates the expression of genes involved in unsaturated FA (UFA) biosynthesis, and also activates the expression of two operons involved in saturated FA (SFA) biosynthesis.

The Vibrio cholerae Minor Pilin TcpB Initiates Assembly and Retraction of the Toxin-Coregulated Pilus.

Type IV pilus (T4P) systems are complex molecular machines that polymerize major pilin proteins into thin filaments displayed on bacterial surfaces. Pilus functions require rapid extension and depolymerization of the pilus, powered by the assembly and retraction ATPases, respectively. A set of low abundance minor pilins influences pilus dynamics by unknown mechanisms.

Origins of pandemic Vibrio cholerae from environmental gene pools.

Some microorganisms can transition from an environmental lifestyle to a pathogenic one. This ecological switch typically occurs through the acquisition of horizontally acquired virulence genes. However, the genomic features that must be present in a population before the acquisition of virulence genes and emergence of pathogenic clones remain unknown.

Effects of tcpB Mutations on Biogenesis and Function of the Toxin-Coregulated Pilus, the Type IVb Pilus of Vibrio cholerae.

Unlabelled: Vibrio cholerae is the etiological agent of the acute intestinal disorder cholera. The toxin-coregulated pilus (TCP), a type IVb pilus, is an essential virulence factor of V. cholerae Recent work has shown that TcpB is a large minor pilin encoded within the tcp operon.

Role of ToxS in the proteolytic cascade of virulence regulator ToxR in Vibrio cholerae.

Two of the primary virulence regulators of Vibrio cholerae, ToxR and TcpP, function together with cognate effector proteins. ToxR undergoes regulated intramembrane proteolysis (RIP) during late stationary phase in response to nutrient limitation at alkaline pH; however, the specific function of its cognate ToxS remains unresolved. In this work, we found that ToxR rapidly becomes undetectable in a ΔtoxS mutant when cultures are exposed to either starvation conditions or after alkaline pH shock individually.

Intestinal Colonization Dynamics of Vibrio cholerae.

To cause the diarrheal disease cholera, Vibrio cholerae must effectively colonize the small intestine. In order to do so, the bacterium needs to successfully travel through the stomach and withstand the presence of agents such as bile and antimicrobial peptides in the intestinal lumen and mucus. The bacterial cells penetrate the viscous mucus layer covering the epithelium and attach and proliferate on its surface.

Proteolysis of virulence regulator ToxR is associated with entry of Vibrio cholerae into a dormant state.

Vibrio cholerae O1 is a natural inhabitant of aquatic environments and causes the diarrheal disease, cholera. Two of its primary virulence regulators, TcpP and ToxR, are localized in the inner membrane. TcpP is encoded on the Vibrio Pathogenicity Island (VPI), a horizontally acquired mobile genetic element, and functions primarily in virulence gene regulation.

The 40-residue insertion in Vibrio cholerae FadR facilitates binding of an additional fatty acyl-CoA ligand.

FadR is a master regulator of fatty acid metabolism and influences virulence in certain members of Vibrionaceae. Among FadR homologues of the GntR family, the Vibrionaceae protein is unusual in that it contains a C-terminal 40-residue insertion. Here we report the structure of Vibrio cholerae FadR (VcFadR) alone, bound to DNA, and in the presence of a ligand, oleoyl-CoA.

Cholera: Environmental Reservoirs and Impact on Disease Transmission.

Vibrio cholerae is widely known to be the etiological agent of the life-threatening diarrheal disease cholera. Cholera remains a major scourge in many developing countries, infecting hundreds of thousands every year. Remarkably, V.

Cholera: Environmental Reservoirs and Impact on Disease Transmission.

is widely known to be the etiological agent of the life-threatening diarrheal disease cholera. Cholera remains a major scourge in many developing countries, infecting hundreds of thousands every year. Remarkably, is a natural inhabitant of brackish riverine, estuarine, and coastal waters, and only a subset of strains are known to be pathogenic to humans.

Secretion of TcpF by the Vibrio cholerae toxin-coregulated pilus biogenesis apparatus requires an N-terminal determinant.

Type IV pili are important for microcolony formation, biofilm formation, twitching motility, and attachment. We and others have shown that type IV pili are important for protein secretion across the outer membrane, similar to type II secretion systems. This study explored the relationship between protein secretion and pilus formation in Vibrio cholerae.

Growth and maintenance of Escherichia coli laboratory strains.

Escherichia coli is a Gram-negative bacterium, commonly used in both teaching and research laboratories. This unit includes protocols for the growth and maintenance of E. coli in any teaching- or research-associated laboratory.

Characterization of BreR interaction with the bile response promoters breAB and breR in Vibrio cholerae.

The Vibrio cholerae BreR protein is a transcriptional repressor of the breAB efflux system operon, which encodes proteins involved in bile resistance. In a previous study (F. A.

The crystal structure of AphB, a virulence gene activator from Vibrio cholerae, reveals residues that influence its response to oxygen and pH.

Expression of the two critical virulence factors of Vibrio cholerae, toxin-coregulated pilus and cholera toxin, is initiated at the tcpPH promoter by the regulators AphA and AphB. AphA is a winged helix DNA-binding protein that enhances the ability of AphB, a LysR-type transcriptional regulator, to activate tcpPH expression. We present here the 2.

Vibriocidal assays to determine the antibody titer of patient sera samples.

The vibriocidal titer assay can be used to detect antibodies against Vibrio cholerae in serum samples, serving as an indicator of prior infection and potential protection against cholera. The assay can be utilized in research and clinical settings to test the effectiveness of vaccines, and also in epidemiological studies relevant to cholera transmission and surveillance. This unit outlines the steps involved in conducting an easily interpreted colorimetric vibriocidal titer assay with a relatively short turnaround time for results of around 8 hr, with final result observations in 24 hr.

Characterization of Vibrio cholerae O1 El Tor biotype variant clinical isolates from Bangladesh and Haiti, including a molecular genetic analysis of virulence genes.

Vibrio cholerae serogroup O1, the causative agent of the diarrheal disease cholera, is divided into two biotypes: classical and El Tor. Both biotypes produce the major virulence factors toxin-coregulated pilus (TCP) and cholera toxin (CT). Although possessing genotypic and phenotypic differences, El Tor biotype strains displaying classical biotype traits have been reported and subsequently were dubbed El Tor variants.

Protection and attachment of Vibrio cholerae mediated by the toxin-coregulated pilus in the infant mouse model.

Colonization of the human small intestine by Vibrio cholerae is an essential step in pathogenesis that requires the type IV toxin-coregulated pilus (TCP). To date, three functions of TCP have been characterized: it serves as the CTXΦ receptor, secretes the colonization factor TcpF, and functions in microcolony formation by mediating bacterium-bacterium interactions. Although type IV pili in other pathogenic bacteria have been characterized as playing a major role in attachment to epithelial cells, there are very few studies to suggest that TCP acts as an attachment factor.

Nutrient-dependent, rapid transition of Vibrio cholerae to coccoid morphology and expression of the toxin co-regulated pilus in this form.

The acute diarrhoeal disease cholera is caused by the aquatic pathogen Vibrio cholerae upon ingestion of contaminated food or water by the human host. The mechanisms by which V. cholerae is able to persist and survive in the host and aquatic environments have been studied for years; however, little is known about the factors involved in the adaptation or response of V.

The physical basis of type 4 pilus-mediated microcolony formation by Vibrio cholerae O1.

The Vibrio cholerae toxin co-regulated pilus (TCP) is a type 4b pilus that mediates bacterial microcolony formation, which is essential for intestinal colonization. Structural analyses have defined a surface domain of the TcpA pilin subunit that is displayed repeatedly around the pilus filament surface and forms the molecular basis for pilus-pilus interactions required for microcolony formation. The physical attributes of this domain that lead to pilus-pilus association between bacteria are not known.