scholarly journals The Vibrio cholerae FlgM Homologue Is an Anti-σ28 Factor That Is Secreted through the Sheathed Polar Flagellum

2004 ◽  
Vol 186 (14) ◽  
pp. 4613-4619 ◽  
Author(s):  
Nidia E. Correa ◽  
Jeffrey R. Barker ◽  
Karl E. Klose
Keyword(s):  
Vibrio Cholerae ◽  
Transcriptional Activity ◽  
Human Pathogen ◽  
Class Iii ◽  
Nonstructural Proteins ◽  
Infant Mouse ◽  
Repressive Effect ◽  
Flagellar Assembly ◽  
Mouse Intestine ◽  
Flagellar Genes

ABSTRACT Vibrio cholerae has a single polar sheathed flagellum that propels the cells of this bacterium. Flagellar synthesis, motility, and chemotaxis have all been linked to virulence in this human pathogen. V. cholerae expresses flagellar genes in a hierarchy consisting of σ54- and σ28-dependent transcription. In other bacteria, σ28 transcriptional activity is controlled by an anti-σ28 factor, FlgM. We demonstrate that the V. cholerae FlgM homologue (i) physically interacts with σ28, (ii) has a repressive effect on some V. cholerae σ28-dependent flagellar promoters, and (iii) is secreted through the polar sheathed flagellum, consistent with anti-σ28 activity. Interestingly, FlgM does not have a uniform repressive effect on all σ28-dependent promoters, as determined by measurement of σ28-dependent transcription in cells either lacking FlgM (ΔflgM) or incapable of secretion (ΔfliF). Further analysis of a ΔfliF strain revealed that this flagellar assembly block causes a decrease in class III (FlrC- and σ54-dependent) and class IV (σ28-dependent), but not class II (FlrA- and σ54-dependent), flagellar transcription. V. cholerae flgM and fliA (encodes σ28) mutants were only modestly affected in their ability to colonize the infant mouse intestine, a measure of virulence. Our results demonstrate that V. cholerae FlgM functions as an anti-σ28 factor and that the sheathed flagellum is competent for secretion of nonstructural proteins.

scholarly journals Spatiotemporal Analysis of Acid Adaptation-Mediated Vibrio cholerae Hyperinfectivity

2004 ◽  
Vol 72 (4) ◽  
pp. 2405-2407 ◽  
Author(s):  
Michael J. Angelichio ◽  
D. Scott Merrell ◽  
Andrew Camilli
Keyword(s):  
Small Intestine ◽  
Vibrio Cholerae ◽  
Spatiotemporal Analysis ◽  
Rapid Onset ◽  
Multiplication Rate ◽  
Acid Adaptation ◽  
Infant Mouse ◽  
Mouse Intestine ◽  
Kinetics Of ◽  
Transcriptional Induction

ABSTRACT Acid adaptation has previously been shown to increase the infectivity of Vibrio cholerae in the infant mouse model. To better understand this phenomenon, we monitored the spatial distribution and temporal changes in the ratios of acid-adapted cells to unadapted V. cholerae cells in the small intestine, as well as the timing of virulence factor expression. We found that the competitive advantage afforded by acid adaptation does not become manifest until greater than 3 h postinfection; thus, acid adaptation does not increase V. cholerae passage through the gastric acid barrier. Additionally, acid-adapted and unadapted V. cholerae cells colonize the same sections of the small intestine and show similar kinetics of transcriptional induction of the virulence genes tcpA and ctxA. These studies suggest that the increased infectivity of acid-adapted V. cholerae is due to a more rapid onset of multiplication and/or to an increased multiplication rate within the infant mouse intestine.

scholarly journals The LonA Protease Regulates Biofilm Formation, Motility, Virulence, and the Type VI Secretion System in Vibrio cholerae

2016 ◽  
Vol 198 (6) ◽  
pp. 973-985 ◽  
Author(s):  
Andrew Rogers ◽  
Loni Townsley ◽  
Ana L. Gallego-Hernandez ◽  
Sinem Beyhan ◽  
Laura Kwuan ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Secretion System ◽  
Lon Protease ◽  
Human Pathogen ◽  
Type Vi Secretion System ◽  
Cyclic Diguanylate ◽  
Content Type ◽  
Infant Mouse ◽  
Type Vi Secretion

ABSTRACTThe presence of the Lon protease in all three domains of life hints at its biological importance. The prokaryotic Lon protease is responsible not only for degrading abnormal proteins but also for carrying out the proteolytic regulation of specific protein targets. Posttranslational regulation by Lon is known to affect a variety of physiological traits in many bacteria, including biofilm formation, motility, and virulence. Here, we identify the regulatory roles of LonA in the human pathogenVibrio cholerae. We determined that the absence of LonA adversely affects biofilm formation, increases swimming motility, and influences intracellular levels of cyclic diguanylate. Whole-genome expression analysis revealed that the message abundance of genes involved in biofilm formation was decreased but that the message abundances of those involved in virulence and the type VI secretion system were increased in alonAmutant compared to the wild type. We further demonstrated that alonAmutant displays an increase in type VI secretion system activity and is markedly defective in colonization of the infant mouse. These findings suggest that LonA plays a critical role in the environmental survival and virulence ofV. cholerae.IMPORTANCEBacteria utilize intracellular proteases to degrade damaged proteins and adapt to changing environments. The Lon protease has been shown to be important for environmental adaptation and plays a crucial role in regulating the motility, biofilm formation, and virulence of numerous plant and animal pathogens. We find that LonA of the human pathogenV. choleraeis in line with this trend, as the deletion of LonA leads to hypermotility and defects in both biofilm formation and colonization of the infant mouse. In addition, we show that LonA regulates levels of cyclic diguanylate and the type VI secretion system. Our observations add to the known regulatory repertoire of the Lon protease and the current understanding ofV. choleraephysiology.

scholarly journals A Novel Regulatory Protein Involved in Motility of Vibrio cholerae

2009 ◽  
Vol 191 (22) ◽  
pp. 7027-7038 ◽  
Author(s):  
Manuel Moisi ◽  
Christian Jenul ◽  
Susan M. Butler ◽  
Aaron New ◽  
Sarah Tutz ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Gene Transcription ◽  
Deletion Mutant ◽  
Expression Patterns ◽  
Regulatory Protein ◽  
Regulatory Elements ◽  
Flagellar Gene ◽  
Class Iii ◽  
Reading Frame ◽  
Infant Mouse

ABSTRACT The facultative pathogen Vibrio cholerae is the causative agent of the human intestinal disease cholera. Both motility and chemotaxis of V. cholerae have been shown to contribute to the virulence and spread of cholera. The flagellar gene operons are organized into a hierarchy composed of four classes (I to IV) based on their temporal expression patterns. Some regulatory elements involved in flagellar gene expression have been elucidated, but regulation is complex and flagellar biogenesis in V. cholerae is not completely understood. In this study, we determined that the virulence defect of a V. cholerae cheW1 deletion mutant was due to polar effects on the downstream open reading frame VC2058 (flrD). Expression of flrD in trans restored the virulence defect of the cheW1 deletion mutant, and deletion of flrD resulted in a V. cholerae strain attenuated for virulence, as determined by using the infant mouse intestinal colonization model. The flrD mutant strain exhibited decreased transcription of class III and IV flagellar genes and reduced motility. Transcription of the flrD promoter, which lies within the coding sequence of cheW1, is independent of the flagellar transcriptional activators FlrA and RpoN, which activate class II genes, indicating that flrD does not fit into any of the four flagellar gene classes. Genetic epistasis studies revealed that the two-component system FlrBC, which is required for class III and IV flagellar gene transcription, acts downstream of flrD. We hypothesize that the inner membrane protein FlrD interacts with the cytoplasmic FlrBC complex to activate class III and IV gene transcription.

scholarly journals Characterization of Ferric and Ferrous Iron Transport Systems in Vibrio cholerae

2006 ◽  
Vol 188 (18) ◽  
pp. 6515-6523 ◽  
Author(s):  
Elizabeth E. Wyckoff ◽  
Alexandra R. Mey ◽  
Andreas Leimbach ◽  
Carolyn F. Fisher ◽  
Shelley M. Payne
Keyword(s):  
Vibrio Cholerae ◽  
Transport System ◽  
Iron Transport ◽  
Iron Acquisition ◽  
Shigella Flexneri ◽  
Transport Systems ◽  
Infant Mouse ◽  
Mouse Intestine ◽  
Dependent Transport

ABSTRACT Vibrio cholerae has multiple iron acquisition systems, including TonB-dependent transport of heme and of the catechol siderophore vibriobactin. Strains defective in both of these systems grow well in laboratory media and in the infant mouse intestine, indicating the presence of additional iron acquisition systems. Previously uncharacterized potential iron transport systems, including a homologue of the ferrous transporter Feo and a periplasmic binding protein-dependent ATP binding cassette (ABC) transport system, termed Fbp, were identified in the V. cholerae genome sequence. Clones encoding either the Feo or the Fbp system exhibited characteristics of iron transporters: both repressed the expression of lacZ cloned under the control of a Fur-regulated promoter in Escherichia coli and also conferred growth on a Shigella flexneri mutant that has a severe defect in iron transport. Two other ABC transporters were also evaluated but were negative by these assays. Transport of radioactive iron by the Feo system into the S. flexneri iron transport mutant was stimulated by the reducing agent ascorbate, consistent with Feo functioning as a ferrous transporter. Conversely, ascorbate inhibited transport by the Fbp system, suggesting that it transports ferric iron. The growth of V. cholerae strains carrying mutations in one or more of the potential iron transport genes indicated that both Feo and Fbp contribute to iron acquisition. However, a mutant defective in the vibriobactin, Fbp, and Feo systems was not attenuated in a suckling mouse model, suggesting that at least one other iron transport system can be used in vivo.

scholarly journals DNA Damage and Reactive Nitrogen Species are Barriers to Vibrio cholerae Colonization of the Infant Mouse Intestine

2011 ◽  
Vol 7 (2) ◽  
pp. e1001295 ◽  
Author(s):  
Bryan W. Davies ◽  
Ryan W. Bogard ◽  
Nicole M. Dupes ◽  
Tyler A. I. Gerstenfeld ◽  
Lyle A. Simmons ◽  
...  
Keyword(s):  
Dna Damage ◽  
Vibrio Cholerae ◽  
Reactive Nitrogen Species ◽  
Reactive Nitrogen ◽  
Nitrogen Species ◽  
Infant Mouse ◽  
Mouse Intestine

scholarly journals Sialic Acid Catabolism Confers a Competitive Advantage to Pathogenic Vibrio cholerae in the Mouse Intestine

2009 ◽  
Vol 77 (9) ◽  
pp. 3807-3816 ◽  
Author(s):  
Salvador Almagro-Moreno ◽  
E. Fidelma Boyd
Keyword(s):  
Sialic Acid ◽  
Vibrio Cholerae ◽  
Sialic Acids ◽  
Infant Mouse ◽  
Pathogenic Vibrio ◽  
Important Relationship ◽  
Mouse Intestine ◽  
El Tor ◽  
Mouse Model Of Infection ◽  
Competition Assays

ABSTRACT Sialic acids comprise a family of nine-carbon ketosugars that are ubiquitous on mammalian mucous membranes. However, sialic acids have a limited distribution among Bacteria and are confined mainly to pathogenic and commensal species. Vibrio pathogenicity island 2 (VPI-2), a 57-kb region found exclusively among pathogenic strains of Vibrio cholerae, contains a cluster of genes (nan-nag) putatively involved in the scavenging (nanH), transport (dctPQM), and catabolism (nanA, nanE, nanK, and nagA) of sialic acid. The capacity to utilize sialic acid as a carbon and energy source might confer an advantage to V. cholerae in the mucus-rich environment of the gut, where sialic acid availability is extensive. In this study, we show that V. cholerae can utilize sialic acid as a sole carbon source. We demonstrate that the genes involved in the utilization of sialic acid are located within the nan-nag region of VPI-2 by complementation of E scherichia coli mutants and gene knockouts in V. cholerae N16961. We show that nanH, dctP, nanA, and nanK are highly expressed in V. cholerae grown on sialic acid. By using the infant mouse model of infection, we show that V. cholerae ΔnanA strain SAM1776 is defective in early intestinal colonization stages. In addition, SAM1776 shows a decrease in the competitive index in colonization-competition assays comparing the mutant strain with both O1 El Tor and classical strains. Our data indicate an important relationship between the catabolism of sialic acid and bacterial pathogenesis, stressing the relevance of the utilization of the resources found in the host's environment.

scholarly journals Lipidation of an FlrC-Dependent Protein Is Required for Enhanced Intestinal Colonization by Vibrio cholerae

2007 ◽  
Vol 190 (1) ◽  
pp. 231-239 ◽  
Author(s):  
David C. Morris ◽  
Fen Peng ◽  
Jeffrey R. Barker ◽  
Karl E. Klose
Keyword(s):  
Outer Membrane ◽  
Vibrio Cholerae ◽  
Wild Type Strain ◽  
Intestinal Colonization ◽  
Class Iii ◽  
Wild Type ◽  
Colonization Factor ◽  
Dependent Protein ◽  
Fusion Analysis ◽  
Flagellar Genes

ABSTRACT Vibrio cholerae, the causative agent of cholera, has a sheathed, polar flagellum, and motility has been linked to virulence. An operon with two genes, flgO and flgP (VC2207 and VC2206), is positively regulated by FlrC, the activator of class III flagellar genes. Deletion of flgP results in a nonmotile phenotype, demonstrating the requirement of this gene for V. cholerae motility. V. cholerae ΔflgP cells synthesize fragile and defective flagella but transcribe flagellar genes similar to the wild-type strain. PhoA fusion analysis indicated that the putative lipoprotein FlgP is localized external to the cytoplasm, and fractionation demonstrated that it was localized to the outer membrane. Mutagenesis of the site of lipidation of FlgP (C18G) prevented [3H]palmitate incorporation and outer membrane localization. Interestingly, FlgP with the mutation C18G [FlgP(C18G)] could complement the ΔflgP mutant for motility, and the cells synthesized wild-type flagella. The ΔflgP mutant strain was defective for intestinal colonization (∼20-fold), but FlgP(C18G) was unable to complement this defect, demonstrating that lipidation of FlgP is essential for its role in intestinal colonization but not flagellar synthesis. FlgP thus represents a novel V. cholerae intestinal colonization factor that is regulated by the flagellar transcription hierarchy.

scholarly journals Hyperinfectivity of Human-Passaged Vibrio cholerae Can Be Modeled by Growth in the Infant Mouse

2005 ◽  
Vol 73 (10) ◽  
pp. 6674-6679 ◽  
Author(s):  
Ashfaqul Alam ◽  
Regina C. LaRocque ◽  
Jason B. Harris ◽  
Cecily Vanderspurt ◽  
Edward T. Ryan ◽  
...  
Keyword(s):  
Mouse Model ◽  
Competitive Advantage ◽  
Vibrio Cholerae ◽  
Type Iv Pili ◽  
Human Intestine ◽  
Epidemic Spread ◽  
Infant Mouse ◽  
Type Iv ◽  
Mouse Intestine ◽  
Human Stool

ABSTRACT It has previously been shown that passage of Vibrio cholerae through the human intestine imparts a transient hyperinfectious phenotype that may contribute to the epidemic spread of cholera. The mechanism underlying this human-passaged hyperinfectivity is incompletely understood, in part due to inherent difficulties in recovering and studying organisms that are freshly passed in human stool. Here, we demonstrate that passage of V. cholerae through the infant mouse intestine leads to an equivalent degree of hyperinfectivity as passage through the human host. We have used this infant mouse model of host-passaged hyperinfectivity to characterize the timing and the anatomic location of the competitive advantage of mouse-passaged V. cholerae as well as the contribution of three type IV pili to the phenotype.

scholarly journals A Membrane-Associated Protein, FliX, Is Required for an Early Step in Caulobacter Flagellar Assembly

1998 ◽  
Vol 180 (8) ◽  
pp. 2175-2185 ◽  
Author(s):  
Christian D. Mohr ◽  
Joanna K. MacKichan ◽  
Lucy Shapiro
Keyword(s):  
Cell Cycle ◽  
Caulobacter Crescentus ◽  
Signal Sequence ◽  
Early Stage ◽  
Class Ii ◽  
Flagellar Gene ◽  
Class Iii ◽  
Isolation And Characterization ◽  
Flagellar Assembly ◽  
Flagellar Genes

ABSTRACT The ordered assembly of the Caulobacter crescentusflagellum is accomplished in part through the organization of the flagellar structural genes in a regulatory hierarachy of four classes. Class II genes are the earliest to be expressed and are activated at a specific time in the cell cycle by the CtrA response regulator. In order to identify gene products required for early events in flagellar assembly, we used the known phenotypes of class II mutants to identify new class II flagellar genes. In this report we describe the isolation and characterization of a flagellar gene, fliX. AfliX null mutant is nonmotile, lacks a flagellum, and exhibits a marked cell division defect. Epistasis experiments placedfliX within class II of the flagellar regulatory hierarchy, suggesting that FliX functions at an early stage in flagellar assembly. The fliX gene encodes a 15-kDa protein with a putative N-terminal signal sequence. Expression of fliX is under cell cycle control, with transcription beginning relatively early in the cell cycle and peaking in Caulobacter predivisional cells. Full expression of fliX was found to be dependent onctrA, and DNase I footprinting analysis demonstrated a direct interaction between CtrA and the fliX promoter. ThefliX gene is located upstream and is divergently transcribed from the class III flagellar gene flgI, which encodes the basal body P-ring monomer. Analysis of thefliX-flgI intergenic region revealed an arrangement ofcis-acting elements similar to that of another set ofCaulobacter class II and class III flagellar genes,fliL-flgF, that is also divergently transcribed. In parallel with the FliL protein, FliX copurifies with the membrane fraction, and although its expression is cell cycle controlled, the protein is present throughout the cell cycle.

scholarly journals ToxR-Independent Expression of Cholera Toxin from the Replicative Form of CTXφ

1998 ◽  
Vol 66 (1) ◽  
pp. 394-397 ◽  
Author(s):  
Sara Lazar ◽  
Matthew K. Waldor
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Toxin Production ◽  
Recipient Strain ◽  
Replicative Form ◽  
Filamentous Bacteriophage ◽  
Infant Mouse ◽  
Mouse Intestine

ABSTRACT The ctxAB operon, which encodes cholera toxin, resides in the genome of CTXφ, a filamentous bacteriophage. WithinVibrio cholerae cells, the CTXφ genome can exist either as a replicating plasmid or as a prophage integrated into the chromosome. Previous work established that ToxR is required for chromosomal ctxAB expression. We have learned that strains harboring the CTXφ replicative form produce cholera toxin under all conditions tested, independently of ToxR. During passage of CTXφ lysogens through the infant mouse intestine, transduction of CTXφ to a recipient strain can be detected, indicating that phage excision and replication occur in vivo. These results suggest that phage induction might provide a novel mechanism for the regulation of cholera toxin production.

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