scholarly journals Systematic genetic dissection of chitin degradation and uptake inVibrio cholerae

2017 ◽  
Author(s):  
Chelsea A. Hayes ◽  
Triana N. Dalia ◽  
Ankur B. Dalia
Keyword(s):  
Vibrio Cholerae ◽  
Aquatic Environment ◽  
Diarrheal Disease ◽  
Natural Transformation ◽  
Degradation Products ◽  
Chitinase Activity ◽  
Crustacean Zooplankton ◽  
Genetic Dissection ◽  
Chitin Degradation ◽  
Environmental Reservoir

SUMMARYVibrio choleraeis a natural resident of the aquatic environment, where a common nutrient is the chitinous exoskeletons of microscopic crustaceans. Chitin utilization requires chitinases, which degrade this insoluble polymer into soluble chitin oligosaccharides. These oligosaccharides also serve as an inducing cue for natural transformation inVibriospecies. There are 7 predicted endochitinase-like genes in theV. choleraegenome. Here, we systematically dissect the contribution of each gene to growth on chitin as well as induction of natural transformation. Specifically, we created a strain that lacks all 7 putative chitinases and from this strain, generated a panel of strains where each expresses a single chitinase. We also generated expression plasmids to ectopically express all 7 chitinases in our chitinase deficient strain. Through this analysis, we found that low levels of chitinase activity are sufficient for natural transformation, while growth on insoluble chitin as a sole carbon source requires more robust and concerted chitinase activity. We also assessed the role that the three uptake systems for the chitin degradation products GlcNAc, (GlcNAc)2, and (GlcN)2, play in chitin utilization and competence induction. Cumulatively, this study provides mechanistic details for how this pathogen utilizes chitin to thrive and evolve in its environmental reservoir.ORIGINALITY-SIGNIFICANCE STATEMENTVibrio cholerae, the causative agent of the diarrheal disease cholera, interacts with the chitinous shells of crustacean zooplankton in the aquatic environment, which serves as an environmental reservoir for this pathogen. It degrades and utilizes chitin-derived products as a source of carbon and nitrogen. Also, chitin serves as an inducing cue for natural transformation – an important mechanism of horizontal gene transfer in this species. Here, we systematically dissect the genes required for chitin degradation and uptake, and characterize the role of these genes for growth on chitin as a nutrient and during chitininduced natural transformation. Thus, this study provides mechanistic details for how this pathogen utilizes chitin to thrive and evolve in its environmental reservoir.

scholarly journals Genes Activated byVibrio choleraeupon Exposure toCaenorhabditis elegansReveal the Mannose-Sensitive Hemagglutinin To Be Essential for Colonization

mSphere ◽  
2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Cornelia List ◽  
Andreas Grutsch ◽  
Claudia Radler ◽  
Fatih Cakar ◽  
Franz G. Zingl ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Vibrio Cholerae ◽  
Developmental Delay ◽  
Growth Retardation ◽  
Aquatic Environment ◽  
Diarrheal Disease ◽  
Phenotypic Characterization ◽  
Human Pathogen ◽  
Content Type ◽  
Human Host

ABSTRACTDuring its life cycle, the facultative human pathogenVibrio cholerae, which is the causative agent of the diarrheal disease cholera, needs to adapt to a variety of different conditions, such as the human host or the aquatic environment. Importantly, cholera infections originate from the aquatic reservoir whereV. choleraepersists between the outbreaks. In the aquatic environment, bacteria are constantly threatened by predatory protozoa and nematodes, but our knowledge of the response pathways and adaptation strategies ofV. choleraeto such stressors is limited. Using a temporally controlled reporter system of transcription, we identified more than 100 genes ofV. choleraeinduced upon exposure to the nematodeCaenorhabditis elegans, which emerged recently as a valuable model for environmental predation during the aquatic lifestyle ofV. cholerae. Besides others, we identified and validated the genes encoding the mannose-sensitive hemagglutinin (MSHA) type IV pilus to be significantly induced upon exposure to the nematode. Subsequent analyses demonstrated that the mannose-sensitive hemagglutinin is crucial for attachment ofV. choleraein the pharynx of the worm and initiation of colonization, which results in growth retardation and developmental delay ofC. elegans. Thus, the surface adhesion factor MSHA could be linked to a fitness advantage ofV. choleraeupon contact with bacterium-grazing nematodes.IMPORTANCEThe waterborne diarrheal disease cholera is caused by the bacteriumVibrio cholerae. The facultative human pathogen persists as a natural inhabitant in the aquatic ecosystem between outbreaks. In contrast to the human host,V. choleraerequires a different set of genes to survive in this hostile environment. For example, predatory micrograzers are commonly found in the aquatic environment and use bacteria as a nutrient source, but knowledge of the interaction between bacterivorous grazers andV. choleraeis limited. In this study, we successfully adapted a genetic reporter technology and identified more than 100 genes activated byV. choleraeupon exposure to the bacterium-grazing nematodeCaenorhabditis elegans. This screen provides a first glimpse into responses and adaptational strategies of the bacterial pathogen against such natural predators. Subsequent phenotypic characterization revealed the mannose-sensitive hemagglutinin to be crucial for colonization of the worm, which causes developmental delay and growth retardation.

scholarly journals Role of Chitin for Harbouring of Toxigenic Vibrio cholerae O1 El Tor in Aquatic Environment

1970 ◽  
Vol 25 (1) ◽  
pp. 26-30 ◽  
Author(s):  
M Mahmud Hasan ◽  
Sucharit Basu Neogi ◽  
Iqbal Kabir Jahid ◽  
M Sirajul Islam ◽  
Anwara Begum
Keyword(s):  
Vibrio Cholerae ◽  
Aquatic Environment ◽  
Genotypic Variation ◽  
Aquatic Organisms ◽  
Crustacean Zooplankton ◽  
Term Survival ◽  
Cellular Density ◽  
Main Component ◽  
El Tor

Vibrio cholerae, the etiological agent of cholera is an autochthonous bacterium of aquatic environment, often found attached to crustacean zooplankton. Chitin is the main component of crustacean exoskeleton, an insoluble polysaccharide. V. cholerae can secrete chitinase enzymes, which can facilitate the bacterium's association with chitinous aquatic organisms to utilize it as a potential nutrient source. In the present study, we checked the role of chitin for long term survival of V. cholerae. Laboratory based microcosms were prepared with purified artificial chitin chips and a toxigenic strain of V. cholerae O1 El Tor. In the presence of chitin, V. cholerae was found in a higher cellular density for >61 days in culturable condition than control water. We observed that the older chitin chips gradually thinner which indicated that V. cholerae utilized chitin. PCR experiment confirmed the presence of the bacterium's cholera toxin coding gene (ctxA) and membrane associated virulent gene ompU remained unaltered. Finally, from randomly amplified polymorphic DNA (RAPD) analysis no significant genotypic variation was detected in the bacterium's genome after its long time association with chitin. Keywords: Vibrio cholerae; Chitin; Polymerase chain reaction (PCR); MicrocosmDOI: http://dx.doi.org/10.3329/bjm.v25i1.4851 Bangladesh J Microbiol, Volume 25, Number 1, June 2008, pp 26-30

scholarly journals Role of Zooplankton Diversity in Vibrio cholerae Population Dynamics and in the Incidence of Cholera in the Bangladesh Sundarbans

2011 ◽  
Vol 77 (17) ◽  
pp. 6125-6132 ◽  
Author(s):  
Guillaume Constantin de Magny ◽  
Pronob K. Mozumder ◽  
Christopher J. Grim ◽  
Nur A. Hasan ◽  
M. Niamul Naser ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Ecological Factors ◽  
Crustacean Zooplankton ◽  
Content Type ◽  
Life Threatening ◽  
Bodies Of Water ◽  
Zooplankton Communities

ABSTRACTVibrio cholerae, a bacterium autochthonous to the aquatic environment, is the causative agent of cholera, a severe watery, life-threatening diarrheal disease occurring predominantly in developing countries.V. cholerae, including both serogroups O1 and O139, is found in association with crustacean zooplankton, mainly copepods, and notably in ponds, rivers, and estuarine systems globally. The incidence of cholera and occurrence of pathogenicV. choleraestrains with zooplankton were studied in two areas of Bangladesh: Bakerganj and Mathbaria. Chitinous zooplankton communities of several bodies of water were analyzed in order to understand the interaction of the zooplankton population composition with the population dynamics of pathogenicV. choleraeand incidence of cholera. Two dominant zooplankton groups were found to be consistently associated with detection ofV. choleraeand/or occurrence of cholera cases, namely, rotifers and cladocerans, in addition to copepods. Local differences indicate there are subtle ecological factors that can influence interactions betweenV. cholerae, its plankton hosts, and the incidence of cholera.

scholarly journals Differentiation of Chitinase-Active and Non-Chitinase-Active Subpopulations of a Marine Bacterium during Chitin Degradation

2000 ◽  
Vol 66 (8) ◽  
pp. 3566-3573 ◽  
Author(s):  
Ace M. Baty ◽  
Callie C. Eastburn ◽  
Zhenjun Diwu ◽  
Somkiet Techkarnjanaruk ◽  
Amanda E. Goodman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aqueous Phase ◽  
Marine Bacterium ◽  
Fluorescent Protein ◽  
Degradation Products ◽  
Chitinase Activity ◽  
Bacterial Survival ◽  
Chitin Degradation ◽  
Active Population ◽  
Green Fluorescent

ABSTRACT The ability of marine bacteria to adhere to detrital particulate organic matter and rapidly switch on metabolic genes in an effort to reproduce is an important response for bacterial survival in the pelagic marine environment. The goal of this investigation was to evaluate the relationship between chitinolytic gene expression and extracellular chitinase activity in individual cells of the marine bacterium Pseudoalteromonas sp. strain S91 attached to solid chitin. A green fluorescent protein reporter gene under the control of the chiA promoter was used to evaluatechiA gene expression, and a precipitating enzyme-linked fluorescent probe, ELF-97–N-acetyl-β-d-glucosaminide, was used to evaluate extracellular chitinase activity among cells in the bacterial population. Evaluation of chiA expression and ELF-97 crystal location at the single-cell level revealed two physiologically distinct subpopulations of S91 on the chitin surface: one that was chitinase active and remained associated with the surface and another that was non-chitinase active and released daughter cells into the bulk aqueous phase. It is hypothesized that the surface-associated, non-chitinase-active population is utilizing chitin degradation products that were released by the adjacent chitinase-active population for cell replication and dissemination into the bulk aqueous phase.

scholarly journals Investigation of degradation products of cocaine and benzoylecgonine in the aquatic environment

2013 ◽  
Vol 443 ◽  
pp. 200-208 ◽  
Author(s):  
Lubertus Bijlsma ◽  
Clara Boix ◽  
Wilfried M.A. Niessen ◽  
María Ibáñez ◽  
Juan V. Sancho ◽  
...  
Keyword(s):  
Aquatic Environment ◽  
Degradation Products

scholarly journals Growth Phase Regulation of Vibrio cholerae RTX Toxin Export

2006 ◽  
Vol 189 (5) ◽  
pp. 1827-1835 ◽  
Author(s):  
Bethany Kay Boardman ◽  
Brian M. Meehan ◽  
Karla J. Fullner Satchell
Keyword(s):  
Stationary Phase ◽  
Vibrio Cholerae ◽  
Growth Phase ◽  
Diarrheal Disease ◽  
Outer Membrane Vesicles ◽  
Transcriptional Level ◽  
Type I ◽  
Bacterial Membranes ◽  
Rtx Toxin ◽  
Phase Regulation

ABSTRACT Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, secretes several “accessory” toxins, including RTX toxin, which causes the cross-linking of the actin cytoskeleton. RTX toxin is exported to the extracellular milieu by an atypical type I secretion system (T1SS), and we previously noted that RTX-associated activity is detectable only in supernatant fluids from log phase cultures. Here, we investigate the mechanisms for regulating RTX toxin activity in supernatant fluids. We find that exported proteases are capable of destroying RTX activity and may therefore play a role in the growth phase regulation of toxin activity. We determined that the absence of RTX toxin in stationary-phase culture supernatant fluids is also due to a lack of toxin secretion and not attributable to solely proteolytic degradation. We ascertained that the T1SS apparatus is regulated at the transcriptional level by growth phase control that is independent of quorum sensing, unlike other virulence factors of V. cholerae. Additionally, in stationary-phase cultures, all RTX toxin activity is associated with bacterial membranes or outer membrane vesicles.

scholarly journals The Transcriptional Regulator VqmA Increases Expression of the Quorum-Sensing Activator HapR in Vibrio cholerae

2006 ◽  
Vol 188 (7) ◽  
pp. 2446-2453 ◽  
Author(s):  
Zhi Liu ◽  
Ansel Hsiao ◽  
Adam Joelsson ◽  
Jun Zhu
Keyword(s):  
Quorum Sensing ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Constitutive Expression ◽  
Physiological Role ◽  
Transcriptional Regulator ◽  
Protease Production ◽  
Dependent Manner ◽  
Cell Densities

ABSTRACT Vibrio cholerae is the causative agent of the severe diarrheal disease cholera. A number of environmental stimuli regulate virulence gene expression in V. cholerae, including quorum-sensing signals. At high cell densities, quorum sensing in V. cholerae invokes a series of signal transduction pathways in order to activate the expression of the master regulator HapR, which then represses the virulence regulon and biofilm-related genes and activates protease production. In this study, we identified a transcriptional regulator, VqmA (VCA1078), that activates hapR expression at low cell densities. Under in vitro inducing conditions, constitutive expression of VqmA represses the virulence regulon in a HapR-dependent manner. VqmA increases hapR transcription as measured by the activity of the hapR-lacZ reporter, and it increases HapR production as measured by Western blotting. Using a heterogenous luxCDABE cosmid, we found that VqmA stimulates quorum-sensing regulation at lower cell densities and that this stimulation bypasses the known LuxO-small-RNA regulatory circuits. Furthermore, we showed that VqmA regulates hapR transcription directly by binding to its promoter region and that expression of vqmA is cell density dependent and autoregulated. The physiological role of VqmA is also discussed.

scholarly journals CryoEM structure of the type IVa pilus secretin required for natural competence in Vibrio cholerae

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Sara J. Weaver ◽  
Davi R. Ortega ◽  
Matthew H. Sazinsky ◽  
Triana N. Dalia ◽  
Ankur B. Dalia ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Vibrio Cholerae ◽  
Natural Transformation ◽  
Domain Architecture ◽  
Genetic Material ◽  
Surface Binding ◽  
Exogenous Dna ◽  
Insight Into

Abstract Natural transformation is the process by which bacteria take up genetic material from their environment and integrate it into their genome by homologous recombination. It represents one mode of horizontal gene transfer and contributes to the spread of traits like antibiotic resistance. In Vibrio cholerae, a type IVa pilus (T4aP) is thought to facilitate natural transformation by extending from the cell surface, binding to exogenous DNA, and retracting to thread this DNA through the outer membrane secretin, PilQ. Here, we use a functional tagged allele of VcPilQ purified from native V. cholerae cells to determine the cryoEM structure of the VcPilQ secretin in amphipol to ~2.7 Å. We use bioinformatics to examine the domain architecture and gene neighborhood of T4aP secretins in Proteobacteria in comparison with VcPilQ. This structure highlights differences in the architecture of the T4aP secretin from the type II and type III secretion system secretins. Based on our cryoEM structure, we design a series of mutants to reversibly regulate VcPilQ gate dynamics. These experiments support the idea of VcPilQ as a potential druggable target and provide insight into the channel that DNA likely traverses to promote the spread of antibiotic resistance via horizontal gene transfer by natural transformation.

scholarly journals Structural basis for virulence regulation in Vibrio cholerae by unsaturated fatty acid components of bile

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Justin T. Cruite ◽  
Gabriela Kovacikova ◽  
Kenzie A. Clark ◽  
Anne K. Woodbrey ◽  
Karen Skorupski ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Structural Model ◽  
Unsaturated Fatty Acids ◽  
Diarrheal Disease ◽  
Bacterial Pathogen ◽  
Virulence Gene ◽  
Structural Basis ◽  
Active Conformation ◽  
Structural Mechanism ◽  
Virulence Gene Regulation

AbstractThe AraC/XylS-family transcriptional regulator ToxT is the master virulence activator of Vibrio cholerae, the gram-negative bacterial pathogen that causes the diarrheal disease cholera. Unsaturated fatty acids (UFAs) found in bile inhibit the activity of ToxT. Crystal structures of inhibited ToxT bound to UFA or synthetic inhibitors have been reported, but no structure of ToxT in an active conformation had been determined. Here we present the 2.5 Å structure of ToxT without an inhibitor. The structure suggests release of UFA or inhibitor leads to an increase in flexibility, allowing ToxT to adopt an active conformation that is able to dimerize and bind DNA. Small-angle X-ray scattering was used to validate a structural model of an open ToxT dimer bound to the cholera toxin promoter. The results presented here provide a detailed structural mechanism for virulence gene regulation in V. cholerae by the UFA components of bile and other synthetic ToxT inhibitors.

Sign in / Sign up

Export Citation Format

Share Document