scholarly journals Listeria monocytogenes virulence factors are secreted in biologically active Extracellular Vesicles

2017 ◽  
Author(s):  
Carolina Coelho ◽  
Lisa Brown ◽  
Maria Maryam ◽  
Meagan C. Burnet ◽  
Jennifer E. Kyle ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Extracellular Vesicles ◽  
Outer Membrane Vesicles ◽  
Biologically Active ◽  
Host Cells ◽  
Immunogold Electron Microscopy ◽  
Dependent Manner ◽  
Listeriolysin O ◽  
Gram Positive ◽  
Gram Positive Bacteria

ABSTRACTOuter membrane vesicles produced by Gram-negative bacteria have been studied for half a century but the possibility that Gram-positive bacteria secreted extracellular vesicles (EVs) was not pursued due to the assumption that the thick peptidoglycan cell wall would prevent their release to the environment. However, following discovery in fungi, which also have cell walls, EVs have now been described for a variety of Gram-positive bacteria. EVs purified from Gram-positive bacteriaare implicated in virulence, toxin release and transference to host cells, eliciting immune responses, and spread of antibiotic resistance. Listeria monocytogenes is a Gram-positive bacterium that is the etiological agent of listeriosis. Here we report that L. monocytogenes produces EVs with diameter ranging from 20-200 nm, containing the pore-forming toxin listeriolysin O(LLO) and phosphatidylinositol-specific phospholipase C (PI-PLC). Using simultaneous metabolite, protein, and lipid extraction (MPLEx) multi-omics we characterized protein, lipid and metabolite composition of bacterial cells and secreted EVs and found that EVs carry the majority of listerial virulence proteins. Cell-free EV preparations were toxic to the murine macrophage cell line J774.16, in a LLO-dependent manner, evidencing EV biological activity. The deletion of plcA increased EV toxicity, suggesting PI-PLC can restrain LLO activity. Using immunogold electron microscopy we detect LLO localization at several organelles within infected human epithelial cells and with high-resolution fluorescence imaging we show that dynamic lipid structures are released from L. monocytogenes that colocalize with LLO during infection. Our findings demonstrate that L. monocytogenes utilize EVs for toxin release and implicate these structures in mammalian cytotoxicity.

scholarly journals Listeriolysin O as a Reporter To Identify Constitutive and In Vivo-Inducible Promoters in the Pathogen Listeria monocytogenes

2000 ◽  
Vol 68 (6) ◽  
pp. 3242-3250 ◽  
Author(s):  
Iharilalao Dubail ◽  
Patrick Berche ◽  
Alain Charbit
Keyword(s):  
Listeria Monocytogenes ◽  
Host Cells ◽  
Transcriptional Analysis ◽  
Listeriolysin O ◽  
Gram Positive ◽  
Genome Database ◽  
Inducible Promoters ◽  
Genes Encoding

ABSTRACT Listeria monocytogenes is a facultative intracellular gram-positive bacterium capable of growing in the cytoplasm of infected host cells. Bacterial escape from the phagosomal vacuole of infected cells is mainly mediated by the pore-forming hemolysin listeriolysin O (LLO) encoded by hly. LLO-negative mutants of L. monocytogenes are avirulent in the mouse model. We have developed a genetic system with hly as a reporter gene allowing the identification of both constitutive and in vivo-inducible promoters of this pathogen. Genomic libraries were created by randomly inserting L. monocytogenes chromosomal fragments upstream of the promoterless hly gene cloned into gram-positive and gram-negative shuttle vectors and expressed in an LLO-negative mutant strain. With this hly-based promoter trap system, combined with access to the L. monocytogenes genome database, we identified 20 in vitro-transcribed genes, including genes encoding (i) p60, a previously known virulence gene, (ii) a putative new hemolysin, and (iii) two proteins of the general protein secretion pathway. By using the hly-based system as an in vivo expression technology tool, nine in vivo-induced loci of L. monocytogenes were identified, including genes encoding (i) the previously known in vivo-inducible phosphatidylinositol phospholipase C and (ii) a putative N-acetylglucosamine epimerase, possibly involved in teichoic acid biosynthesis. The use of hly as a reporter is a simple and powerful alternative to classical methods for transcriptional analysis to monitor promoter activity in L. monocytogenes.

scholarly journals Listeria monocytogenes Desensitizes Immune Cells to Subsequent Ca2+ Signaling via Listeriolysin O-Induced Depletion of Intracellular Ca2+ Stores

2007 ◽  
Vol 76 (2) ◽  
pp. 857-862 ◽  
Author(s):  
Nelson O. Gekara ◽  
Lothar Groebe ◽  
Nuno Viegas ◽  
Siegfried Weiss
Keyword(s):  
Immune System ◽  
Listeria Monocytogenes ◽  
Calcium Signaling ◽  
Immune Cells ◽  
Prolonged Exposure ◽  
Cellular Responses ◽  
Host Cells ◽  
Listeriolysin O ◽  
Gram Positive Bacteria ◽  
Intracellular Ca

ABSTRACT Listeriolysin O (LLO), the pore-forming toxin of Listeria monocytogenes, is a prototype of the cholesterol-dependent cytolysins (CDCs) secreted by several pathogenic and nonpathogenic gram-positive bacteria. In addition to mediating the escape of the bacterium into the cytosol, this toxin is generally believed to be a central player in host-pathogen interactions during L. monocytogenes infection. LLO triggers the influx of Ca2+ into host cells as well as the release of Ca2+ from intracellular stores. Thus, many of the cellular responses induced by LLO are related to calcium signaling. Interestingly, in this study, we report that prolonged exposure to LLO desensitizes cells to Ca2+ mobilization upon subsequent stimulations with LLO. Cells preexposed to LLO-positive L. monocytogenes but not to the LLO-deficient Δhly mutant were found to be highly refractory to Ca2+ induction in response to receptor-mediated stimulation. Such cells also exhibited diminished Ca2+ signals in response to stimulation with LLO and thapsigargin. The presented results suggest that this phenomenon is due to the depletion of intracellular Ca2+ stores. The ability of LLO to desensitize immune cells provides a significant hint about the possible role played by CDCs in the evasion of the immune system by bacterial pathogens.

scholarly journals Staphylococcus aureus Extracellular Vesicles Carry Biologically Active β-Lactamase

2013 ◽  
Vol 57 (6) ◽  
pp. 2589-2595 ◽  
Author(s):  
Jaewook Lee ◽  
Eun-Young Lee ◽  
Si-Hyun Kim ◽  
Dae-Kyum Kim ◽  
Kyong-Su Park ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Extracellular Vesicles ◽  
Extracellular Vesicle ◽  
Biologically Active ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Heat Treated ◽  
Protease Digestion

ABSTRACTGram-positive bacteria naturally produce extracellular vesicles. However, little is known regarding the functions of Gram-positive bacterial extracellular vesicles, especially in the bacterial community. Here, we investigated the role ofStaphylococcus aureusextracellular vesicles in interbacterial communication to cope with antibiotic stress. We found thatS. aureusliberated BlaZ, a β-lactamase protein, via extracellular vesicles. These extracellular vesicles enabled other ampicillin-susceptible Gram-negative and Gram-positive bacteria to survive in the presence of ampicillin. However,S. aureusextracellular vesicles did not mediate the survival of tetracycline-, chloramphenicol-, or kanamycin-susceptible bacteria. Moreover,S. aureusextracellular vesicles did not contain theblaZgene. In addition, the heat-treatedS. aureusextracellular vesicles did not mediate the survival of ampicillin-susceptible bacteria. The β-lactamase activities ofS. aureussoluble and extracellular vesicle-associated BlaZ were similar, but only the extracellular vesicle-associated BlaZ was resistant to protease digestion, which suggests that the enzymatic activity of BlaZ in extracellular vesicles is largely protected by the vesicle structure. Our observations provide evidence of the important role ofS. aureusextracellular vesicles in antibiotic resistance, which allows the polymicrobial community to continue to evolve and prosper against antibiotics.

scholarly journals Detection of Bacterial Membrane Vesicles by NOD-Like Receptors

2021 ◽  
Vol 22 (3) ◽  
pp. 1005
Author(s):  
Ella L. Johnston ◽  
Begoña Heras ◽  
Thomas A. Kufer ◽  
Maria Kaparakis-Liaskos
Keyword(s):  
Inflammatory Diseases ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Innate Immune ◽  
Host Cells ◽  
Bacterial Membrane ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Key Driver

Bacterial membrane vesicles (BMVs) are nanoparticles produced by both Gram-negative and Gram-positive bacteria that can function to modulate immunity in the host. Both outer membrane vesicles (OMVs) and membrane vesicles (MVs), which are released by Gram-negative and Gram-positive bacteria, respectively, contain cargo derived from their parent bacterium, including immune stimulating molecules such as proteins, lipids and nucleic acids. Of these, peptidoglycan (PG) and lipopolysaccharide (LPS) are able to activate host innate immune pattern recognition receptors (PRRs), known as NOD-like receptors (NLRs), such as nucleotide-binding oligomerisation domain-containing protein (NOD) 1, NOD2 and NLRP3. NLR activation is a key driver of inflammation in the host, and BMVs derived from both pathogenic and commensal bacteria have been shown to package PG and LPS in order to modulate the host immune response using NLR-dependent mechanisms. Here, we discuss the packaging of immunostimulatory cargo within OMVs and MVs, their detection by NLRs and the cytokines produced by host cells in response to their detection. Additionally, commensal derived BMVs are thought to shape immunity and contribute to homeostasis in the gut, therefore we also highlight the interactions of commensal derived BMVs with NLRs and their roles in limiting inflammatory diseases.

scholarly journals Helicobacter pylori Outer Membrane Vesicles and Extracellular Vesicles from Helicobacter pylori-Infected Cells in Gastric Disease Development

2021 ◽  
Vol 22 (9) ◽  
pp. 4823
Author(s):  
María Fernanda González ◽  
Paula Díaz ◽  
Alejandra Sandoval-Bórquez ◽  
Daniela Herrera ◽  
Andrew F. G. Quest
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Outer Membrane ◽  
Extracellular Vesicles ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Gastric Epithelium ◽  
Infected Cells ◽  
H Pylori

Extracellular vesicles (EVs) are cell-derived vesicles important in intercellular communication that play an essential role in host-pathogen interactions, spreading pathogen-derived as well as host-derived molecules during infection. Pathogens can induce changes in the composition of EVs derived from the infected cells and use them to manipulate their microenvironment and, for instance, modulate innate and adaptive inflammatory immune responses, both in a stimulatory or suppressive manner. Gastric cancer is one of the leading causes of cancer-related deaths worldwide and infection with Helicobacter pylori (H. pylori) is considered the main risk factor for developing this disease, which is characterized by a strong inflammatory component. EVs released by host cells infected with H. pylori contribute significantly to inflammation, and in doing so promote the development of disease. Additionally, H. pylori liberates vesicles, called outer membrane vesicles (H. pylori-OMVs), which contribute to atrophia and cell transformation in the gastric epithelium. In this review, the participation of both EVs from cells infected with H. pylori and H. pylori-OMVs associated with the development of gastric cancer will be discussed. By deciphering which functions of these external vesicles during H. pylori infection benefit the host or the pathogen, novel treatment strategies may become available to prevent disease.

scholarly journals The Listeria monocytogenes hemolysin has an acidic pH optimum to compartmentalize activity and prevent damage to infected host cells

2002 ◽  
Vol 156 (6) ◽  
pp. 1029-1038 ◽  
Author(s):  
Ian J. Glomski ◽  
Margaret M. Gedde ◽  
Albert W. Tsang ◽  
Joel A. Swanson ◽  
Daniel A. Portnoy
Keyword(s):  
Listeria Monocytogenes ◽  
Bacterial Pathogen ◽  
Cytolytic Activity ◽  
Host Cells ◽  
Adaptive Mutation ◽  
Acidic Ph ◽  
Listeriolysin O ◽  
Lysosomal Hydrolases ◽  
Ph Optimum ◽  
Neutral Ph

Listeria monocytogenes is a facultative intracellular bacterial pathogen that escapes from a phagosome and grows in the host cell cytosol. The pore-forming cholesterol-dependent cytolysin, listeriolysin O (LLO), mediates bacterial escape from vesicles and is ∼10-fold more active at an acidic than neutral pH. By swapping dissimilar residues from a pH-insensitive orthologue, perfringolysin O (PFO), we identified leucine 461 as unique to pathogenic Listeria and responsible for the acidic pH optimum of LLO. Conversion of leucine 461 to the threonine present in PFO increased the hemolytic activity of LLO almost 10-fold at a neutral pH. L. monocytogenes synthesizing LLO L461T, expressed from its endogenous site on the bacterial chromosome, resulted in a 100-fold virulence defect in the mouse listeriosis model. These bacteria escaped from acidic phagosomes and initially grew normally in cells and spread cell to cell, but prematurely permeabilized the host membrane and killed the cell. These data show that the acidic pH optimum of LLO results from an adaptive mutation that acts to limit cytolytic activity to acidic vesicles and prevent damage in the host cytosol, a strategy also used by host cells to compartmentalize lysosomal hydrolases.

scholarly journals A Pilot Study of Bacteriological Population Changes through Potable Water Treatment and Distribution

2000 ◽  
Vol 66 (1) ◽  
pp. 268-276 ◽  
Author(s):  
Cheryl D. Norton ◽  
Mark W. LeChevallier
Keyword(s):  
Pilot Study ◽  
Biologically Active ◽  
Plate Count ◽  
Identification System ◽  
Population Changes ◽  
Gram Positive ◽  
Pipe Surface ◽  
Treated Water ◽  
Gram Positive Bacteria ◽  
Biofilm Development

ABSTRACT This pilot study compares the compositions of bacterial biofilms in pipe networks supplied with water containing either high levels of biodegradable organic matter (BOM) or low levels of BOM (conventionally or biologically treated, respectively). The Microbial Identification System for fatty acid analysis was utilized in this study to identify a large number of organisms (>1,400) to determine population changes in both conventionally and biologically treated water and biofilms. Data generated during this study indicated that suspended bacteria have little impact on biofilms, and despite treatment (conventional or biological), suspended microbial populations were similar following disinfection. Prechlorination with free chlorine resulted not only in reduced plate count values but also in a dramatic shift in the composition of the bacterial population to predominately gram-positive bacteria. Chlorination of biologically treated water produced the same shifts toward gram-positive bacteria. Removal of assimilable organic carbon by the biologically active filters slowed the rate of biofilm accumulation, but biofilm levels were similar to those found in conventionally treated water within several weeks. Iron pipes stimulated the rate of biofilm development, and bacterial levels on disinfected iron pipes exceeded those for chlorinated polyvinyl chloride pipes. The study showed that the iron pipe surface dramatically influenced the composition, activity, and disinfection resistance of biofilm bacteria.

scholarly journals Cholera Toxin Encapsulated within Several Vibrio cholerae O1 Serotype Inaba Outer Membrane Vesicles Lacks a Functional B-Subunit

Toxins ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 207 ◽  
Author(s):  
Elnaz Rasti ◽  
Angela Brown
Keyword(s):  
Outer Membrane ◽  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Biologically Active ◽  
Host Cells ◽  
Free Form ◽  
Type Ii Secretion ◽  
Secondary Mechanism

Cholera toxin (CT), the major virulence factor of Vibrio cholerae, is an AB5 toxin secreted through the type II secretion system (T2SS). Upon secretion, the toxin initiates endocytosis through the interaction of the B pentamer with the GM1 ganglioside receptor on small intestinal cells. In addition to the release of CT in the free form, the bacteria secrete CT in association with outer membrane vesicles (OMVs). Previously, we demonstrated that strain 569B releases OMVs that encapsulate CT and which interact with host cells in a GM1-independent mechanism. Here, we have demonstrated that OMV-encapsulated CT, while biologically active, does not exist in an AB5 form; rather, the OMVs encapsulate two enzymatic A-subunit (CTA) polypeptides. We further investigated the assembly and secretion of the periplasmic CT and found that a major fraction of periplasmic CTA does not participate in the CT assembly process and instead is continuously encapsulated within the OMVs. Additionally, we found that the encapsulation of CTA fragments in OMVs is conserved among several Inaba O1 strains. We further found that under conditions in which the amount of extracellularly secreted CT increases, the concentration of OMV-encapsulated likewise CTA increases. These results point to a secondary mechanism for the secretion of biologically active CT that does not depend on the CTB-GM1 interaction for endocytosis.

scholarly journals Avoidance of Autophagy Mediated by PlcA or ActA Is Required for Listeria monocytogenes Growth in Macrophages

2015 ◽  
Vol 83 (5) ◽  
pp. 2175-2184 ◽  
Author(s):  
Gabriel Mitchell ◽  
Liang Ge ◽  
Qiongying Huang ◽  
Chen Chen ◽  
Sara Kianian ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Wild Type Strain ◽  
Fold Increase ◽  
Host Cells ◽  
Listeriolysin O ◽  
Wild Type ◽  
Conjugation System ◽  
Content Type ◽  
A Cell ◽  
Gain Access

Listeria monocytogenesis a facultative intracellular pathogen that escapes from phagosomes and grows in the cytosol of infected host cells. Most of the determinants that govern its intracellular life cycle are controlled by the transcription factor PrfA, including the pore-forming cytolysin listeriolysin O (LLO), two phospholipases C (PlcA and PlcB), and ActA. We constructed a strain that lacked PrfA but expressed LLO from a PrfA-independent promoter, thereby allowing the bacteria to gain access to the host cytosol. This strain did not grow efficiently in wild-type macrophages but grew normally in macrophages that lacked ATG5, a component of the autophagy LC3 conjugation system. This strain colocalized more with the autophagy marker LC3 (42% ± 7%) at 2 h postinfection, which constituted a 5-fold increase over the colocalization exhibited by the wild-type strain (8% ± 6%). While mutants lacking the PrfA-dependent virulence factor PlcA, PlcB, or ActA grew normally, a double mutant lacking both PlcA and ActA failed to grow in wild-type macrophages and colocalized more with LC3 (38% ± 5%). Coexpression of LLO and PlcA in a PrfA-negative strain was sufficient to restore intracellular growth and decrease the colocalization of the bacteria with LC3. In a cell-free assay, purified PlcA protein blocked LC3 lipidation, a key step in early autophagosome biogenesis, presumably by preventing the formation of phosphatidylinositol 3-phosphate (PI3P). The results of this study showed that avoidance of autophagy byL. monocytogenesprimarily involves PlcA and ActA and that either one of these factors must be present forL. monocytogenesgrowth in macrophages.

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