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.

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 AVibrio choleraeBolA-like protein is required for proper cell shape and cell envelope integrity

2019 ◽  
Author(s):  
Aurore Fleurie ◽  
Abdelrahim Zoued ◽  
Laura Alvarez ◽  
Kelly M. Hines ◽  
Felipe Cava ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Cell Morphology ◽  
Cell Shape ◽  
Cell Envelope ◽  
Intestinal Colonization ◽  
Iron Sulfur Cluster ◽  
Sulfur Cluster ◽  
Iron Sulfur ◽  
Morphological Defects

AbstractBolA family proteins are conserved in gram-negative bacteria and many eukaryotes. While diverse cellular phenotypes have been linked to this protein family, the molecular pathways through which these proteins mediate their effects are not well-described. Here, we investigated the role of BolA family proteins inVibrio cholerae, the cholera pathogen. LikeEscherichia coli,V. choleraeencodes two BolA proteins, BolA and IbaG. However, in marked contrast toE. coli, wherebolAis linked to cell shape andibaGis not, inV. cholerae, bolAmutants lack morphological defects, whereasibaGproved critical for the generation and/or maintenance of the pathogen’s morphology. Notably, the bizarre-shaped, multi-polar, elongated and wide cells that predominated in exponential phase ΔibaG V. choleraecultures were not observed in stationary phase cultures. TheV. choleraeΔibaGmutant exhibited increased sensitivity to cell envelope stressors, including cell wall acting antibiotics and bile, and was defective in intestinal colonization. ΔibaG V. choleraehad reduced peptidoglycan and lipid II and altered outer membrane lipids, likely contributing to the mutant’s morphological defects and sensitivity to envelope stressors. Transposon-insertion sequencing analysis ofibaG’s genetic interactions suggested thatibaGis involved in several processes involved in the generation and homeostasis of the cell envelope. Furthermore, co-purification studies revealed that IbaG interacts with proteins containing iron-sulfur clusters or involved in their assembly. Collectively, our findings suggest thatV. choleraeIbaG controls cell morphology and cell envelope integrity through its role in biogenesis or trafficking of iron-sulfur cluster proteins.ImportanceBolA-like proteins are conserved across prokaryotes and eukaryotes. These proteins have been linked to a variety of phenotypes, but the pathways and mechanisms through which they act have not been extensively characterized. Here, we unraveled the role of the BolA-like protein IbaG in the cholera pathogenVibrio cholerae. The absence of IbaG was associated with dramatic changes in cell morphology, sensitivity to envelope stressors, and intestinal colonization defects. IbaG was found to be required for biogenesis of several components of theV. choleraecell envelope and to interact with numerous iron-sulfur cluster containing proteins and factors involved in their assembly. Thus, our findings suggest that IbaG governsV. choleraecell shape and cell envelope homeostasis through its effects on iron-sulfur proteins and associated pathways. The diversity of processes involving iron-sulfur containing proteins is likely a factor underlying the range of phenotypes associated with BolA family proteins.

scholarly journals Investigation of the Roles of Toxin-Coregulated Pili and Mannose-Sensitive Hemagglutinin Pili in the Pathogenesis of Vibrio cholerae O139 Infection

1998 ◽  
Vol 66 (2) ◽  
pp. 692-695 ◽  
Author(s):  
Carol O. Tacket ◽  
Ronald K. Taylor ◽  
Genevieve Losonsky ◽  
Yu Lim ◽  
James P. Nataro ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Geometric Mean ◽  
Deletion Mutants ◽  
Intestinal Colonization ◽  
Colonization Factor ◽  
Vibrio Cholerae O139 ◽  
El Tor ◽  
Adult Volunteers

ABSTRACT In this study, adult volunteers were fed tcpA andmshA deletion mutants of V. cholerae O139 strain CVD 112 to determine the role of toxin-coregulated pili (TCP) and mannose-sensitive hemagglutinin (MSHA) in intestinal colonization. Eight of 10 volunteers who received CVD 112 or CVD 112 ΔmshA shed the vaccine strains in their stools; the geometric mean peak excretion for both groups was 1.4 × 105 CFU/g of stool. In contrast, only one of nine recipients of CVD 112 ΔtcpA shed vibrios in his stool (P < 0.01); during the first 24 h after inoculation, 3 × 102 CFU/g was recovered from this volunteer. All recipients of CVD 112 and 8 (80%) of the recipients of CVD 112 ΔmshA developed at least a fourfold rise in vibriocidal titer after immunization. In contrast, only one (11%) of the nine recipients of CVD 112 ΔtcpA developed a fourfold rise in vibriocidal titer (P < 0.01). We conclude that TCP are an important colonization factor of V. cholerae O139 and probably of El Tor V. cholerae O1. In contrast, MSHA does not appear to promote intestinal colonization in humans.

scholarly journals Quantifying Vibrio cholerae Enterotoxicity in a Zebrafish Infection Model

2017 ◽  
Vol 83 (16) ◽  
Author(s):  
Kristie C. Mitchell ◽  
Paul Breen ◽  
Sarah Britton ◽  
Melody N. Neely ◽  
Jeffrey H. Withey
Keyword(s):  
Vibrio Cholerae ◽  
Sewage Treatment ◽  
Watery Diarrhea ◽  
Infection Model ◽  
Intestinal Colonization ◽  
Content Type ◽  
Contaminated Food ◽  
In The Wild ◽  
Low Levels

ABSTRACT Vibrio cholerae is the etiological agent of cholera, an acute intestinal infection in humans characterized by voluminous watery diarrhea. Cholera is spread through ingestion of contaminated food or water, primarily in developing countries that lack the proper infrastructure for proper water and sewage treatment. Vibrio cholerae is an aquatic bacterium that inhabits coastal and estuarine areas, and it is known to have several environmental reservoirs, including fish. Our laboratory has recently described the use of the zebrafish as a new animal model for the study of V. cholerae intestinal colonization, pathogenesis, and transmission. As early as 6 h after exposure to V. cholerae, zebrafish develop diarrhea. Prior work in our laboratory has shown that this is not due to the action of cholera toxin. We hypothesize that accessory toxins produced by V. cholerae are the cause of diarrhea in infected zebrafish. In order to assess the effects of accessory toxins in the zebrafish, it was necessary to develop a method of quantifying diarrheal volume as a measure of pathogenesis. Here, we have adapted cell density, protein, and mucin assays, along with enumeration of V. cholerae in the zebrafish intestinal tract and in the infection water, to achieve this goal. Combined, these assays should help us determine which toxins have the greatest diarrheagenic effect in fish and, consequently, which toxins may play a role in environmental transmission. IMPORTANCE Identification of the accessory toxins that cause diarrhea in zebrafish can help us understand more about the role of fish in the wild as aquatic reservoirs for V. cholerae. It is plausible that accessory toxins can act to prolong colonization and subsequent shedding of V. cholerae back into the environment, thus perpetuating and facilitating transmission during an outbreak. It is also possible that accessory toxins help to maintain low levels of intestinal colonization in fish, giving V. cholerae an advantage when environmental conditions are not optimal for survival in the water. Studies such as this one are critical because fish could be an overlooked source of cholera transmission in the environment.

scholarly journals Environmental Signals Controlling Production of Hemagglutinin/Protease in Vibrio cholerae

2001 ◽  
Vol 69 (10) ◽  
pp. 6549-6553 ◽  
Author(s):  
Jorge A. Benitez ◽  
Anisia J. Silva ◽  
Richard A. Finkelstein
Keyword(s):  
Vibrio Cholerae ◽  
Deletion Mutant ◽  
Receptor Protein ◽  
Intracellular Camp ◽  
Wild Type ◽  
Camp Receptor Protein ◽  
Environmental Signals ◽  
Camp Receptor ◽  
Camp Levels

ABSTRACT Vibrio cholerae hemagglutinin/protease (Hap) was induced upon nutrient limitation and strongly repressed by glucose. Hap was not produced in a mutant defective in the cyclic AMP (cAMP) receptor protein, suggesting that intracellular cAMP levels mediate Hap expression. No difference was found in Hap production between anrpoS deletion mutant and its isogenic wild-type precursor, indicating that the alternate ςs factor is not essential for Hap expression. Based on these and previous results, we discuss the role of Hap in the pathogenesis of cholera.

scholarly journals MetR-Regulated Vibrio cholerae Metabolism Is Required for Virulence

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Ryan W. Bogard ◽  
Bryan W. Davies ◽  
John J. Mekalanos
Keyword(s):  
Amino Acid ◽  
Vibrio Cholerae ◽  
Virulence Factor ◽  
Current Knowledge ◽  
Intestinal Colonization ◽  
Wild Type ◽  
Pathogenic Potential ◽  
Content Type ◽  
Mouse Intestine

ABSTRACTLysR-type transcriptional regulators (LTTRs) are the largest, most diverse family of prokaryotic transcription factors, with regulatory roles spanning metabolism, cell growth and division, and pathogenesis. Using a sequence-defined transposon mutant library, we screened a panel ofV. choleraeEl Tor mutants to identify LTTRs required for host intestinal colonization. Surprisingly, out of 38 LTTRs, only one severely affected intestinal colonization in the suckling mouse model of cholera: the methionine metabolism regulator, MetR. Genetic analysis of genes influenced by MetR revealed thatglyA1andmetJwere also required for intestinal colonization. Chromatin immunoprecipitation of MetR and quantitative reverse transcription-PCR (qRT-PCR) confirmed interaction with and regulation ofglyA1, indicating that misregulation ofglyA1is likely responsible for the colonization defect observed in themetRmutant. TheglyA1mutant was auxotrophic for glycine but exhibited wild-type trimethoprim sensitivity, making folate deficiency an unlikely cause of its colonization defect. MetJ regulatory mutants are not auxotrophic but are likely altered in the regulation of amino acid-biosynthetic pathways, including those for methionine, glycine, and serine, and this misregulation likely explains its colonization defect. However, mutants defective in methionine, serine, and cysteine biosynthesis exhibited wild-type virulence, suggesting that these amino acids can be scavenged in vivo. Taken together, our results suggest that glycine biosynthesis may be required to alleviate an in vivo nutritional restriction in the mouse intestine; however, additional roles for glycine may exist. Irrespective of the precise nature of this requirement, this study illustrates the importance of pathogen metabolism, and the regulation thereof, as a virulence factor.IMPORTANCEVibrio choleraecontinues to be a severe cause of morbidity and mortality in developing countries. Identification ofV. choleraefactors critical to disease progression offers the potential to develop or improve upon therapeutics and prevention strategies. To increase the efficiency of virulence factor discovery, we employed a regulator-centric approach to multiplex our in vivo screening capabilities and allow whole regulons inV. choleraeto be interrogated for pathogenic potential. We identified MetR as a new virulence regulator and serine hydroxymethyltransferase GlyA1 as a new MetR-regulated virulence factor, both required byV. choleraeto colonize the infant mouse intestine. Bacterial metabolism is a prerequisite to virulence, and current knowledge of in vivo metabolism of pathogens is limited. Here, we expand the known role of amino acid metabolism and regulation in virulence and offer new insights into the in vivo metabolic requirements ofV. choleraewithin the mouse intestine.

scholarly journals The Role of Serum Chloride in Acute and Chronic Heart Failure: A Narrative Review

2021 ◽  
Vol 11 (2) ◽  
pp. 87-98
Author(s):  
Frederick Berro Rivera ◽  
Pia Alfonso ◽  
Jem Marie Golbin ◽  
Kevin Lo ◽  
Edgar Lerma ◽  
...  
Keyword(s):  
Heart Failure ◽  
Chloride Channel ◽  
Chloride Channels ◽  
Prognostic Value ◽  
Diuretic Therapy ◽  
Juxtaglomerular Apparatus ◽  
Sodium Chloride Cotransporter ◽  
Serum Chloride ◽  
And Function

Clinical guidelines include diuretics for the treatment of heart failure (HF), not to decrease mortality but to decrease symptoms and hospitalizations. More attention has been paid to the worse outcomes, including mortality, associated with continual diuretic therapy due to hypochloremia. Studies have revealed a pivotal role for serum chloride in the pathophysiology of HF and is now a target of treatment to decrease mortality. The prognostic value of serum chloride in HF has been the subject of much attention. Mechanistically, the macula densa, a region in the renal juxtaglomerular apparatus, relies on chloride levels to sense salt and volume status. The recent discovery of with-no-lysine (K) (WNK) protein kinase as an intracellular chloride sensor sheds light on the possible reason of diuretic resistance in HF. The action of chloride on WNKs results in the upregulation of the sodium-potassium-chloride cotransporter and sodium-chloride cotransporter receptors, which could lead to increased electrolyte and fluid reabsorption. Genetic studies have revealed that a variant of a voltage-sensitive chloride channel (CLCNKA) gene leads to almost a 50% decrease in current amplitude and function of the renal chloride channel. This variant increases the risk of HF. Several trials exploring the prognostic value of chloride in both acute and chronic HF have shown mostly positive results, some even suggesting a stronger role than sodium. However, so far, interventional trials exploring serum chloride as a therapeutic target have been largely inconclusive. This study is a review of the pathophysiologic effects of hypochloremia in HF, the genetics of chloride channels, and clinical trials that are underway to investigate novel approaches to HF management.

scholarly journals HbxB Is a Key Regulator for Stress Response and β-Glucan Biogenesis in Aspergillus nidulans

2021 ◽  
Vol 9 (1) ◽  
pp. 144
Author(s):  
Sung-Hun Son ◽  
Mi-Kyung Lee ◽  
Ye-Eun Son ◽  
Hee-Soo Park
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Aspergillus Nidulans ◽  
Deletion Mutant ◽  
Phenotypic Analysis ◽  
Spore Viability ◽  
Fungal Development ◽  
Expression Of Genes ◽  
Trehalose Biosynthesis

Homeobox transcription factors are conserved in eukaryotes and act as multi-functional transcription factors in filamentous fungi. Previously, it was demonstrated that HbxB governs fungal development and spore viability in Aspergillus nidulans. Here, the role of HbxB in A. nidulans was further characterized. RNA-sequencing revealed that HbxB affects the transcriptomic levels of genes associated with trehalose biosynthesis and response to thermal, oxidative, and radiation stresses in asexual spores called conidia. A phenotypic analysis found that hbxB deletion mutant conidia were more sensitive to ultraviolet stress. The loss of hbxB increased the mRNA expression of genes associated with β-glucan degradation and decreased the amount of β-glucan in conidia. In addition, hbxB deletion affected the expression of the sterigmatocystin gene cluster and the amount of sterigmatocystin. Overall, these results indicated that HbxB is a key transcription factor regulating trehalose biosynthesis, stress tolerance, β-glucan degradation, and sterigmatocystin production in A.nidulans conidia.

scholarly journals Role of chloride channels in bradykinin-induced guinea pig airway vagal C-fibre activation

2005 ◽  
Vol 566 (1) ◽  
pp. 205-212 ◽  
Author(s):  
Min-Goo Lee ◽  
Donald W. MacGlashan ◽  
Bradley J. Undem
Keyword(s):  
Guinea Pig ◽  
Chloride Channels ◽  
C Fibre

scholarly journals Role of the Helicobacter hepaticus Flagellar Sigma Factor FliA in Gene Regulation and Murine Colonization

2008 ◽  
Vol 190 (19) ◽  
pp. 6398-6408 ◽  
Author(s):  
Torsten Sterzenbach ◽  
Lucie Bartonickova ◽  
Wiebke Behrens ◽  
Birgit Brenneke ◽  
Jessika Schulze ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Sigma Factor ◽  
Intestinal Inflammation ◽  
Gall Stone ◽  
Helicobacter Hepaticus ◽  
Intestinal Colonization ◽  
Wild Type ◽  
Chronic Intestinal Inflammation ◽  
Flagellar Genes

ABSTRACT The enterohepatic Helicobacter species Helicobacter hepaticus colonizes the murine intestinal and hepatobiliary tract and is associated with chronic intestinal inflammation, gall stone formation, hepatitis, and hepatocellular carcinoma. Thus far, the role of H. hepaticus motility and flagella in intestinal colonization is unknown. In other, closely related bacteria, late flagellar genes are mainly regulated by the sigma factor FliA (σ28). We investigated the function of the H. hepaticus FliA in gene regulation, flagellar biosynthesis, motility, and murine colonization. Competitive microarray analysis of the wild type versus an isogenic fliA mutant revealed that 11 genes were significantly more highly expressed in wild-type bacteria and 2 genes were significantly more highly expressed in the fliA mutant. Most of these were flagellar genes, but four novel FliA-regulated genes of unknown function were identified. H. hepaticus possesses two identical copies of the gene encoding the FliA-dependent major flagellin subunit FlaA (open reading frames HH1364 and HH1653). We characterized the phenotypes of mutants in which fliA or one or both copies of the flaA gene were knocked out. flaA_1 flaA_2 double mutants and fliA mutants did not synthesize detectable amounts of FlaA and possessed severely truncated flagella. Also, both mutants were nonmotile and unable to colonize mice. Mutants with either flaA gene knocked out produced flagella morphologically similar to those of wild-type bacteria and expressed FlaA and FlaB. flaA_1 mutants which had flagella but displayed reduced motility did not colonize mice, indicating that motility is required for intestinal colonization by H. hepaticus and that the presence of flagella alone is not sufficient.

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