scholarly journals Role of Vibrio cholerae O139 Surface Polysaccharides in Intestinal Colonization

2002 ◽  
Vol 70 (11) ◽  
pp. 5990-5996 ◽  
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.

scholarly journals The Alternative Sigma Factor σE Plays an Important Role in Intestinal Survival and Virulence in Vibrio cholerae

2002 ◽  
Vol 70 (10) ◽  
pp. 5355-5362 ◽  
Author(s):  
Gabriela Kovacikova ◽  
Karen Skorupski
Keyword(s):  
Vibrio Cholerae ◽  
Sigma Factor ◽  
Parental Strain ◽  
Time Course ◽  
Lethal Dose ◽  
Alternative Sigma Factor ◽  
Growth And Survival ◽  
Infant Mouse

ABSTRACT The alternative sigma factor σΕ (RpoE) is involved in the response to extracytoplasmic stress and plays a role in the virulence of a variety of different bacteria. To assess the role of σΕ in Vibrio cholerae pathogenesis, a ΔrpoE mutant was constructed and analyzed using the infant mouse model. The results here show that σΕ contributes significantly to the virulence of V. cholerae. The ΔrpoE mutant was highly attenuated with a 50% lethal dose more than 3 logs higher than that for the parental strain, and its ability to colonize the intestine was reduced approximately 30-fold. A time course of infection revealed that the number of CFU of the ΔrpoE mutant was approximately 1 log lower than that of the parental strain by 12 h postinoculation and decreased further by 24 h. The defect in virulence in the ΔrpoE mutant thus appears to be a diminished ability to survive within the intestinal environment. The results here also show that σΕ is not required for growth and survival of V. cholerae in vitro at high temperatures but is required under other stressful conditions, such as in the presence of 3% ethanol. As in Escherichia coli, the expression of rpoE in V. cholerae is dependent upon two promoters located upstream of the gene, P1 and P2. P1 appears to be σ70 dependent, whereas the downstream promoter, P2, is positively autoregulated by σΕ.

scholarly journals Role of Cyclic Di-GMP during El Tor Biotype Vibrio cholerae Infection: Characterization of the In Vivo-Induced Cyclic Di-GMP Phosphodiesterase CdpA

2008 ◽  
Vol 76 (4) ◽  
pp. 1617-1627 ◽  
Author(s):  
Rita Tamayo ◽  
Stefan Schild ◽  
Jason T. Pratt ◽  
Andrew Camilli
Keyword(s):  
Small Intestine ◽  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Virulence Gene ◽  
Virulence Gene Expression ◽  
Infant Mouse

ABSTRACT In Vibrio cholerae, the second messenger cyclic di-GMP (c-di-GMP) positively regulates biofilm formation and negatively regulates virulence and is proposed to play an important role in the transition from persistence in the environment to survival in the host. Herein we describe a characterization of the infection-induced gene cdpA, which encodes both GGDEF and EAL domains, which are known to mediate diguanylate cyclase and c-di-GMP phosphodiesterase (PDE) activities, respectively. CdpA is shown to possess PDE activity, and this activity is regulated by its inactive degenerate GGDEF domain. CdpA inhibits biofilm formation but has no effect on colonization of the infant mouse small intestine. Consistent with these observations, cdpA is expressed during in vitro growth in a biofilm but is not expressed in vivo until the late stage of infection, after colonization has occurred. To test for a role of c-di-GMP in the early stages of infection, we artificially increased c-di-GMP and observed reduced colonization. This was attributed to a significant reduction in toxT transcription during infection. Cumulatively, these results support a model of the V. cholerae life cycle in which c-di-GMP must be down-regulated early after entering the small intestine and maintained at a low level to allow virulence gene expression, colonization, and motility at appropriate stages of infection.

scholarly journals Tenascin-C in Heart Diseases—The Role of Inflammation

2021 ◽  
Vol 22 (11) ◽  
pp. 5828
Author(s):  
Kyoko Imanaka-Yoshida
Keyword(s):  
Ventricular Remodeling ◽  
Heart Diseases ◽  
Genetically Engineered ◽  
Matricellular Protein ◽  
Myocardial Repair ◽  
Inflammatory Reactions ◽  
Tenascin C ◽  
Genetically Engineered Mice

Tenascin-C (TNC) is a large extracellular matrix (ECM) glycoprotein and an original member of the matricellular protein family. TNC is transiently expressed in the heart during embryonic development, but is rarely detected in normal adults; however, its expression is strongly up-regulated with inflammation. Although neither TNC-knockout nor -overexpressing mice show a distinct phenotype, disease models using genetically engineered mice combined with in vitro experiments have revealed multiple significant roles for TNC in responses to injury and myocardial repair, particularly in the regulation of inflammation. In most cases, TNC appears to deteriorate adverse ventricular remodeling by aggravating inflammation/fibrosis. Furthermore, accumulating clinical evidence has shown that high TNC levels predict adverse ventricular remodeling and a poor prognosis in patients with various heart diseases. Since the importance of inflammation has attracted attention in the pathophysiology of heart diseases, this review will focus on the roles of TNC in various types of inflammatory reactions, such as myocardial infarction, hypertensive fibrosis, myocarditis caused by viral infection or autoimmunity, and dilated cardiomyopathy. The utility of TNC as a biomarker for the stratification of myocardial disease conditions and the selection of appropriate therapies will also be discussed from a clinical viewpoint.

scholarly journals Characterization of Vibrio cholerae O1 El TorgalU and galE Mutants: Influence on Lipopolysaccharide Structure, Colonization, and Biofilm Formation

2001 ◽  
Vol 69 (1) ◽  
pp. 435-445 ◽  
Author(s):  
Jutta Nesper ◽  
Crystal M. Lauriano ◽  
Karl E. Klose ◽  
Dagmar Kapfhammer ◽  
Anita Kraiß ◽  
...  
Keyword(s):  
Organic Acids ◽  
Vibrio Cholerae ◽  
Bile Salts ◽  
Short Chain ◽  
Core Oligosaccharide ◽  
O Antigen ◽  
Mouse Small Intestine ◽  
Vibrio Cholerae O1 ◽  
El Tor

ABSTRACT Recently we described the isolation of spontaneous bacteriophage K139-resistant Vibrio cholerae O1 El Tor mutants. In this study, we identified phage-resistant isolates with intact O antigen but altered core oligosaccharide which were also affected in galactose catabolism; this strains have mutations in the galU gene. We inactivated another gal gene, galE, and the mutant was also found to be defective in the catabolism of exogenous galactose but synthesized an apparently normal lipopolysaccharide (LPS). Both gal mutants as well as a rough LPS (R-LPS) mutant were investigated for the ability to colonize the mouse small intestine. The galU and R-LPS mutants, but not thegalE mutant, were defective in colonization, a phenotype also associated with O-antigen-negative mutants. By investigating several parameters in vitro, we could show that galU and R-LPS mutants were more sensitive to short-chain organic acids, cationic antimicrobial peptides, the complement system, and bile salts as well as other hydrophobic agents, indicating that their outer membrane no longer provides an effective barrier function. O-antigen-negative strains were found to be sensitive to complement and cationic peptides, but they displayed significant resistance to bile salts and short-chain organic acids. Furthermore, we found thatgalU and galE are essential for the formation of a biofilm in a spontaneous phage-resistant rugose variant, suggesting that the synthesis of UDP-galactose via UDP-glucose is necessary for biosynthesis of the exopolysaccharide. In addition, we provide evidence that the production of exopolysaccharide limits the access of phage K139 to its receptor, the O antigen. In conclusion, our results indicate involvement of galU in V. cholerae virulence, correlated with the observed change in LPS structure, and a role for galU and galE in environmental survival of V. cholerae.

scholarly journals On the Importance of the Thiazole Nitrogen in Epothilones: Semisynthesis and Microtubule-Binding Affinity of Deaza-Epothilone C

Chemistry ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 499-509
Author(s):  
Adriana Edenharter ◽  
Lucie Ryckewaert ◽  
Daniela Cintulová ◽  
Juan Estévez-Gallego ◽  
José Fernando Díaz ◽  
...  
Keyword(s):  
Decisive Role ◽  
Ring Closure ◽  
Side Chain ◽  
Microtubule Binding ◽  
Acid Fragment ◽  
Epothilone A ◽  
Thiophene Moiety ◽  
Free Energy Of Binding

Deaza-epothilone C, which incorporates a thiophene moiety in place of the thiazole heterocycle in the natural epothilone side chain, has been prepared by semisynthesis from epothilone A, in order to assess the contribution of the thiazole nitrogen to microtubule binding. The synthesis was based on the esterification of a known epothilone A-derived carboxylic acid fragment and a fully synthetic alcohol building block incorporating the modified side chain segment and subsequent ring-closure by ring-closing olefin metathesis. The latter proceeded with unfavorable selectivity and in low yield. Distinct differences in chemical behavior were unveiled between the thiophene-derived advanced intermediates and what has been reported for the corresponding thiazole-based congeners. Compared to natural epothilone C, the free energy of binding of deaza-epothilone C to microtubules was reduced by ca. 1 kcal/mol or less, thus indicating a distinct but non-decisive role of the thiazole nitrogen in the interaction of epothilones with the tubulin/microtubule system. In contrast to natural epothilone C, deaza-epothilone C was devoid of antiproliferative activity in vitro up to a concentration of 10 μM, presumably due to an insufficient stability in the cell culture medium.

scholarly journals Cooperative Role of Antibodies against Heat-Labile Toxin and the EtpA Adhesin in Preventing Toxin Delivery and Intestinal Colonization by Enterotoxigenic Escherichia coli

2012 ◽  
Vol 19 (10) ◽  
pp. 1603-1608 ◽  
Author(s):  
Koushik Roy ◽  
David J. Hamilton ◽  
James M. Fleckenstein
Keyword(s):  
Escherichia Coli ◽  
Diarrheal Disease ◽  
Vaccine Development ◽  
Enterotoxigenic Escherichia Coli ◽  
Intestinal Colonization ◽  
Content Type ◽  
Heat Labile

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) is an important cause of diarrheal disease in developing countries, where it is responsible for hundreds of thousands of deaths each year. Vaccine development for ETEC has been hindered by the heterogeneity of known molecular targets and the lack of broad-based sustained protection afforded by existing vaccine strategies. In an effort to explore the potential role of novel antigens in ETEC vaccines, we examined the ability of antibodies directed against the ETEC heat-labile toxin (LT) and the recently described EtpA adhesin to prevent intestinal colonizationin vivoand toxin delivery to epithelial cellsin vitro. We demonstrate that EtpA is required for the optimal delivery of LT and that antibodies against this adhesin play at least an additive role in preventing delivery of LT to target intestinal cells when combined with antibodies against either the A or B subunits of the toxin. Moreover, vaccination with a combination of LT and EtpA significantly impaired intestinal colonization. Together, these results suggest that the incorporation of recently identified molecules such as EtpA could be used to enhance current approaches to ETEC vaccine development.

scholarly journals Glucomannan-Mediated Attachment of Rhizobium leguminosarum to Pea Root Hairs Is Required for Competitive Nodule Infection

2008 ◽  
Vol 190 (13) ◽  
pp. 4706-4715 ◽  
Author(s):  
Alan Williams ◽  
Adam Wilkinson ◽  
Martin Krehenbrink ◽  
Daniela M. Russo ◽  
Angeles Zorreguieta ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Rhizobium Leguminosarum ◽  
Root Hairs ◽  
The Other ◽  
Plant Interactions ◽  
Wild Type ◽  
Polysaccharide Synthesis ◽  
Surface Polysaccharides

ABSTRACT The Rhizobium leguminosarum biovar viciae genome contains several genes predicted to determine surface polysaccharides. Mutants predicted to affect the initial steps of polysaccharide synthesis were identified and characterized. In addition to the known cellulose (cel) and acidic exopolysaccharide (EPS) (pss) genes, we mutated three other loci; one of these loci (gmsA) determines glucomannan synthesis and one (gelA) determines a gel-forming polysaccharide, but the role of the other locus (an exoY-like gene) was not identified. Mutants were tested for attachment and biofilm formation in vitro and on root hairs; the mutant lacking the EPS was defective for both of these characteristics, but mutation of gelA or the exoY-like gene had no effect on either type of attachment. The cellulose (celA) mutant attached and formed normal biofilms in vitro, but it did not form a biofilm on root hairs, although attachment did occur. The cellulose-dependent biofilm on root hairs appears not to be critical for nodulation, because the celA mutant competed with the wild-type for nodule infection. The glucomannan (gmsA) mutant attached and formed normal biofilms in vitro, but it was defective for attachment and biofilm formation on root hairs. Although this mutant formed nodules on peas, it was very strongly outcompeted by the wild type in mixed inoculations, showing that glucomannan is critical for competitive nodulation. The polysaccharide synthesis genes around gmsA are highly conserved among other rhizobia and agrobacteria but are absent from closely related bacteria (such as Brucella spp.) that are not normally plant associated, suggesting that these genes may play a wide role in bacterium-plant interactions.

scholarly journals Deletion of a Vibrio cholerae ClC Channel Results in Acid Sensitivity and Enhanced Intestinal Colonization

2003 ◽  
Vol 71 (7) ◽  
pp. 4197-4200 ◽  
Author(s):  
Yanpeng Ding ◽  
Matthew K. Waldor
Keyword(s):  
Vibrio Cholerae ◽  
Chloride Channels ◽  
Deletion Mutant ◽  
Acid Resistance ◽  
Intestinal Colonization ◽  
Acid Sensitivity

ABSTRACT ClC chloride channels are found in all three kingdoms of life though little is known about their functions in prokaryotes. Here we investigated the role of a Vibrio cholerae ClC channel in acid resistance and intestinal colonization. The putative V. cholerae ClC channel was found to confer mild resistance to acid when pH was adjusted with HCl, but not with other acids. Surprisingly, a ClC channel deletion mutant exhibited enhanced intestinal colonization in infant mice.

Evidence for cleavage of [26-14C]cholesterol side-chain by human foetal membranes in vitro

1983 ◽  
Vol 102 (2) ◽  
pp. 288-291 ◽  
Author(s):  
R. Gunasegaram ◽  
A. Loganath ◽  
K. L. Peh ◽  
S. C. Ng ◽  
S. M. M. Karim ◽  
...  
Keyword(s):  
Isotope Dilution ◽  
Strong Evidence ◽  
Side Chain ◽  
Isotope Dilution Analysis ◽  
Spontaneous Labour ◽  
Foetal Membranes

Abstract. With a view to establish the hitherto undescribed role of cholesterol in foetal-membranous steroidogenesis, homogenates of term chorion pars reflexa and amnion pars reflexa and pars placentaris collected from 6 women after spontaneous labour at term (38 to 41 weeks gestation) were incubated with [26-14C]cholesterol. Using reverse-isotope dilution analysis, [14C]isocaproic acid was isolated and characterized. This conversion constitutes strong evidence that C-20, 22-desmolase activity, normally present in the adrenal, gonadal and placental tissues, is present in the homogenates of both membranes. The efficiency of the enzymic conversion suggests that the chorion possesses a more active desmolase system compared to that of the amnion.

scholarly journals Regulation by ToxR-Like Proteins Converges onvttRBExpression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae

2016 ◽  
Vol 198 (11) ◽  
pp. 1675-1682 ◽  
Author(s):  
Kelly A. Miller ◽  
Madeline K. Sofia ◽  
Jacob W. A. Weaver ◽  
Christopher H. Seward ◽  
Michelle Dziejman
Keyword(s):  
Gene Expression ◽  
Cell Death ◽  
Vibrio Cholerae ◽  
Secretion System ◽  
Content Type ◽  
Transcriptional Regulatory ◽  
Type 3 Secretion System ◽  
Type 3

ABSTRACTGenes carried on the type 3 secretion system (T3SS) pathogenicity island ofVibrio choleraenon-O1/non-O139 serogroup strain AM-19226 must be precisely regulated in order for bacteria to cause disease. Previously reported results showed that both T3SS function and the presence of bile are required to cause Caco2-BBE cell cytotoxicity during coculture with strain AM-19226. We therefore investigated additional parameters affectingin vitrocell death, including bacterial load and the role of three transmembrane transcriptional regulatory proteins, VttRA, VttRB, and ToxR. VttRAand VttRBare encoded on the horizontally acquired T3SS genomic island, whereas ToxR is encoded on the ancestral chromosome. While strains carrying deletions in any one of the three transcriptional regulatory genes are unable to cause eukaryotic cell death, the results of complementation studies point to a hierarchy of regulatory control that converges onvttRBexpression. The data suggest both that ToxR and VttRAact upstream of VttRBand that modifying the level of eithervttRAorvttRBexpression can strongly influence T3SS gene expression. We therefore propose a model whereby T3SS activity and, hence,in vitrocytotoxicity are ultimately regulated byvttRBexpression.IMPORTANCEIn contrast to O1 and O139 serogroupV. choleraestrains that cause cholera using two main virulence factors (toxin-coregulated pilus [TCP] and cholera toxin [CT]), O39 serogroup strain AM-19226 uses a type 3 secretion system as its principal virulence mechanism. Although the regulatory network governing TCP and CT expression is well understood, the factors influencing T3SS-associated virulence are not. Using anin vitromammalian cell model to investigate the role of three ToxR-like transmembrane transcriptional activators in causing T3SS-dependent cytotoxicity, we found that expression levels and a hierarchical organization were important for promoting T3SS gene expression. Furthermore, our results suggest that horizontally acquired, ToxR-like proteins act in concert with the ancestral ToxR protein to orchestrate T3SS-mediated pathogenicity.

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