scholarly journals Discovery of Salmonella Virulence Factors Translocated via Outer Membrane Vesicles to Murine Macrophages

2011 ◽  
Vol 79 (6) ◽  
pp. 2182-2192 ◽  
Author(s):  
Hyunjin Yoon ◽  
Charles Ansong ◽  
Joshua N. Adkins ◽  
Fred Heffron
Keyword(s):  
Outer Membrane ◽  
Virulence Factors ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Secretion Systems ◽  
Homologous Proteins ◽  
Content Type ◽  
Small Proteins

ABSTRACTSalmonella entericaserovar Typhimurium, an intracellular pathogen and leading cause of food-borne illness, encodes a plethora of virulence effectors.Salmonellavirulence factors are translocated into host cells and manipulate host cellular activities, providing a more hospitable environment for bacterial proliferation. In this study, we report a new set of virulence factors that is translocated into the host cytoplasm via bacterial outer membrane vesicles (OMV). PagK (or PagK1), PagJ, and STM2585A (or PagK2) are small proteins composed of ∼70 amino acids and have high sequence homology to each other (>85% identity).Salmonellalacking all three homologues was attenuated for virulence in a mouse infection model, suggesting at least partial functional redundancy among the homologues. While each homologue was translocated into the macrophage cytoplasm, their translocation was independent of all threeSalmonellagene-encoded type III secretion systems (T3SSs)–Salmonellapathogenicity island 1 (SPI-1) T3SS, SPI-2 T3SS, and the flagellar system. Selected methods, including direct microscopy, demonstrated that the PagK-homologous proteins were secreted through OMV, which were enriched with lipopolysaccharide (LPS) and outer membrane proteins. Vesicles produced by intracellular bacteria also contained lysosome-associated membrane protein 1 (LAMP1), suggesting the possibility of OMV convergence with host cellular components during intracellular trafficking. This study identified novelSalmonellavirulence factors secreted via OMV and demonstrated that OMV can function as a vehicle to transfer virulence determinants to the cytoplasm of the infected host cell.

scholarly journals Campylobacter jejuni Outer Membrane Vesicles Play an Important Role in Bacterial Interactions with Human Intestinal Epithelial Cells

2012 ◽  
Vol 80 (12) ◽  
pp. 4089-4098 ◽  
Author(s):  
Abdi Elmi ◽  
Eleanor Watson ◽  
Pamela Sandu ◽  
Ozan Gundogdu ◽  
Dominic C. Mills ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Campylobacter Jejuni ◽  
Virulence Factors ◽  
Intestinal Epithelial Cells ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Intestinal Epithelial ◽  
Secretion Systems ◽  
Content Type

ABSTRACTCampylobacter jejuniis the most prevalent cause of food-borne gastroenteritis in the developed world; however, the molecular basis of pathogenesis is unclear. Secretion of virulence factors is a key mechanism by which enteric bacterial pathogens interact with host cells to enhance survival and/or damage the host. However,C. jejunilacks the virulence-associated secretion systems possessed by other enteric pathogens. Many bacterial pathogens utilize outer membrane vesicles (OMVs) for delivery of virulence factors into host cells. In the absence of prototypical virulence-associated secretion systems, OMVs could be an important alternative for the coordinated delivery ofC. jejuniproteins into host cells. Proteomic analysis ofC. jejuni11168H OMVs identified 151 proteins, including periplasmic and outer membrane-associated proteins, but also many determinants known to be important in survival and pathogenesis, including the cytolethal distending toxin (CDT).C. jejuniOMVs contained 16N-linked glycoproteins, indicating a delivery mechanism by which these periplasm-located yet immunogenic glycoproteins can interact with host cells.C. jejuniOMVs possess cytotoxic activity and induce a host immune response from T84 intestinal epithelial cells (IECs), which was not reduced by OMV pretreatment with proteinase K or polymyxin B prior to coincubation with IECs. Pretreatment of IECs with methyl-beta-cyclodextrin partially blocks OMV-induced host immune responses, indicating a role for lipid rafts in host cell plasma membranes during interactions withC. jejuniOMVs. OMVs isolated from aC. jejuni11168HcdtAmutant induced interleukin-8 (IL-8) to the same extent as did wild-type OMVs, suggesting OMV induction of IL-8 is independent of CDT.

scholarly journals Biopearling of Interconnected Outer Membrane Vesicle Chains by a Marine Flavobacterium

2019 ◽  
Vol 85 (19) ◽  
Author(s):  
Tanja Fischer ◽  
Martin Schorb ◽  
Greta Reintjes ◽  
Androniki Kolovou ◽  
Rachel Santarella-Mellwig ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Surface Area ◽  
Algal Blooms ◽  
Membrane Vesicle ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Glycoside Hydrolases ◽  
Content Type ◽  
Degradative Enzymes

ABSTRACT Large surface-to-volume ratios provide optimal nutrient uptake conditions for small microorganisms in oligotrophic habitats. The surface area can be increased with appendages. Here, we describe chains of interconnecting vesicles protruding from cells of strain Hel3_A1_48, affiliating with Formosa spp. within the Flavobacteriia and originating from coastal free-living bacterioplankton. The chains were up to 10 μm long and had vesicles emanating from the outer membrane with a single membrane and a size of 80 to 100 nm by 50 to 80 nm. Cells extruded membrane tubes in the exponential phase, whereas vesicle chains dominated on cells in the stationary growth phase. This formation is known as pearling, a physical morphogenic process in which membrane tubes protrude from liposomes and transform into chains of interconnected vesicles. Proteomes of whole-cell membranes and of detached vesicles were dominated by outer membrane proteins, including the type IX secretion system and surface-attached peptidases, glycoside hydrolases, and endonucleases. Fluorescein-labeled laminarin stained the cells and the vesicle chains. Thus, the appendages provide binding domains and degradative enzymes on their surfaces and probably storage volume in the vesicle lumen. Both may contribute to the high abundance of these Formosa-affiliated bacteria during laminarin utilization shortly after spring algal blooms. IMPORTANCE Microorganisms produce membrane vesicles. One synthesis pathway seems to be pearling that describes the physical formation of vesicle chains from phospholipid vesicles via extended tubes. Bacteria with vesicle chains had been observed as well as bacteria with tubes, but pearling was so far not observed. Here, we report the observation of, initially, tubes and then vesicle chains during the growth of a flavobacterium, suggesting biopearling of vesicle chains. The flavobacterium is abundant during spring bacterioplankton blooms developing after algal blooms and has a special set of enzymes for laminarin, the major storage polysaccharide of microalgae. We demonstrated with fluorescently labeled laminarin that the vesicle chains bind laminarin or contain laminarin-derived compounds. Proteomic analyses revealed surface-attached degradative enzymes on the outer membrane vesicles. We conclude that the large surface area and the lumen of vesicle chains may contribute to the ecological success of this marine bacterium.

scholarly journals How the colonic environment influences Enterohaemorrhagic E. coli outer membrane vesicle production, and the interaction between outer membrane vesicles with human host cells

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Daniel Yara ◽  
Regis Stentz ◽  
Tom Wileman ◽  
Stephanie Schuller
Keyword(s):  
Outer Membrane ◽  
Bile Salts ◽  
Membrane Vesicle ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
T84 Cells ◽  
E Coli

Enterohaemorrhagic E. coli (EHEC) may instigate bloody diarrhoea and haemolytic uraemic syndrome (HUS) due to Shiga toxin (Stx) production. Stx has been detected within outer membrane vesicles (OMVs), which are membrane-derived nanosized proteoliposomes. During colonisation, EHEC encounters many environmental surroundings such as the presence of bile salts and carbon dioxide (CO2). Here, the influence of different intestinal cues on EHEC OMV production was studied. OMV yield was quantified by densitometric analysis of outer membrane proteins F/C and A, following OMV protein separation by SDS-PAGE. Compared to cultures in Luria broth, higher OMV yields were attained following culture in human cell growth medium and simulated colonic environmental medium, with further increases in the presence of bile salts. Interestingly, lower yields were attained in the presence of T84 cells and CO2. The interaction between OMVs and different human cells was also examined by fluorescence microscopy. Here, OMVs incubated with cells showed internalisation by semi confluent but not fully confluent T84 cell monolayers. OMVs were internalised into the lysosomes in confluent Vero and Caco-2 cells, with Stx being transported to the Golgi and then the Endoplasmic reticulum. OMVs were detected within polarised Caco-2 cells, with no impact on the transepithelial electrical resistance by 24 hours. These results suggest that the colonic environmental factors influences OMV production in vivo. Additionally, results highlight the discrepancies which arise when using different cells lines to examine the intestine. Nevertheless, coupled with Stx, OMVs may serve as tools of EHEC which are involved in HUS development.

scholarly journals Role of Pseudomonas aeruginosa Peptidoglycan-Associated Outer Membrane Proteins in Vesicle Formation

2012 ◽  
Vol 195 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Aimee K. Wessel ◽  
Jean Liew ◽  
Taejoon Kwon ◽  
Edward M. Marcotte ◽  
Marvin Whiteley
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Opportunistic Pathogen ◽  
Outer Membrane Vesicles ◽  
Gram Negative Bacteria ◽  
Content Type

ABSTRACTGram-negative bacteria produce outer membrane vesicles (OMVs) that package and deliver proteins, small molecules, and DNA to prokaryotic and eukaryotic cells. The molecular details of OMV biogenesis have not been fully elucidated, but peptidoglycan-associated outer membrane proteins that tether the outer membrane to the underlying peptidoglycan have been shown to be critical for OMV formation in multipleEnterobacteriaceae. In this study, we demonstrate that the peptidoglycan-associated outer membrane proteins OprF and OprI, but not OprL, impact production of OMVs by the opportunistic pathogenPseudomonas aeruginosa. Interestingly, OprF does not appear to be important for tethering the outer membrane to peptidoglycan but instead impacts OMV formation through modulation of the levels of thePseudomonasquinolone signal (PQS), a quorum signal previously shown by our laboratory to be critical for OMV formation. Thus, the mechanism by which OprF impacts OMV formation is distinct from that for other peptidoglycan-associated outer membrane proteins, including OprI.

scholarly journals Lack of Outer Membrane Protein A Enhances the Release of Outer Membrane Vesicles and Survival ofVibrio choleraeand Suppresses Viability ofAcanthamoeba castellanii

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Soni Priya Valeru ◽  
Salah Shanan ◽  
Haifa Alossimi ◽  
Amir Saeed ◽  
Gunnar Sandström ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Protein A ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Wild Type ◽  
Outer Membrane Protein A

Vibrio cholerae, the causative agent of the diarrhoeal disease cholera, survives in aquatic environments. The bacterium has developed a survival strategy to grow and survive insideAcanthamoeba castellanii. It has been shown thatV. choleraeexpresses outer membrane proteins as virulence factors playing a role in the adherence to interacted host cells. This study examined the role of outer membrane protein A (OmpA) and outer membrane vesicles (OMVs) in survival ofV. choleraealone and during its interaction withA. castellanii. The results showed that anOmpAmutant ofV. choleraesurvived longer than wild-typeV. choleraewhen cultivated alone. Cocultivation withA. castellaniienhanced the survival of both bacterial strains andOmpAprotein exhibited no effect on attachment, engulfment, and survival inside the amoebae. However, cocultivation of theOmpAmutant ofV. choleraedecreased the viability ofA. castellaniiand this bacterial strain released more OMVs than wild-typeV. cholerae. Surprisingly, treatment of amoeba cells with OMVs isolated from theOmpAmutant significantly decreased viable counts of the amoeba cells. In conclusion, the results might highlight a regulating rule forOmpAin survival ofV. choleraeand OMVs as a potent virulence factor for this bacterium towards eukaryotes in the environment.

scholarly journals Aggregatibacter actinomycetemcomitans Outer Membrane Vesicles Are Internalized in Human Host Cells and Trigger NOD1- and NOD2-Dependent NF-κB Activation

2014 ◽  
Vol 82 (10) ◽  
pp. 4034-4046 ◽  
Author(s):  
Bernard Thay ◽  
Anna Damm ◽  
Thomas A. Kufer ◽  
Sun Nyunt Wai ◽  
Jan Oscarsson
Keyword(s):  
Outer Membrane ◽  
Hela Cells ◽  
Inflammatory Responses ◽  
Membrane Vesicles ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Outer Membrane Vesicles ◽  
Biologically Active ◽  
Host Cells ◽  
Content Type ◽  
Human Embryonic Kidney Cells

ABSTRACTAggregatibacter actinomycetemcomitansis an oral and systemic pathogen associated with aggressive forms of periodontitis and with endocarditis. We recently demonstrated that outer membrane vesicles (OMVs) disseminated byA. actinomycetemcomitanscould deliver multiple proteins, including biologically active cytolethal distending toxin (CDT), into the cytosol of HeLa cells and human gingival fibroblasts (HGF). In the present work, we have used immunoelectron and confocal microscopy analysis and fluorescently labeled vesicles to further investigate mechanisms forA. actinomycetemcomitansOMV-mediated delivery of bacterial antigens to these host cells. Our results supported that OMVs were internalized into the perinuclear region of HeLa cells and HGF. Colocalization analysis revealed that internalized OMVs colocalized with the endoplasmic reticulum and carried antigens, detected using an antibody specific to wholeA. actinomycetemcomitansserotype a cells. Consistent with OMV internalization mediating intracellular antigen exposure, the vesicles acted as strong inducers of cytoplasmic peptidoglycan sensor NOD1- and NOD2-dependent NF-κB activation in human embryonic kidney cells. Moreover, NOD1 was the main sensor of OMV-delivered peptidoglycan in myeloid THP1 cells, contributing to the overall inflammatory responses induced by the vesicles. This work reveals a role ofA. actinomycetemcomitansOMVs as a trigger of innate immunity via carriage of NOD1- and NOD2-active pathogen-associated molecular patterns (PAMPs).

scholarly journals Virulence and Immunomodulatory Roles of Bacterial Outer Membrane Vesicles

2010 ◽  
Vol 74 (1) ◽  
pp. 81-94 ◽  
Author(s):  
Terri N. Ellis ◽  
Meta J. Kuehn
Keyword(s):  
Outer Membrane ◽  
Virulence Factors ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Gram Negative ◽  
Stress Response Pathway ◽  
Degradative Enzymes ◽  
Bacterial Virulence Factor ◽  
Molecular Patterns

SUMMARY Outer membrane (OM) vesicles are ubiquitously produced by Gram-negative bacteria during all stages of bacterial growth. OM vesicles are naturally secreted by both pathogenic and nonpathogenic bacteria. Strong experimental evidence exists to categorize OM vesicle production as a type of Gram-negative bacterial virulence factor. A growing body of data demonstrates an association of active virulence factors and toxins with vesicles, suggesting that they play a role in pathogenesis. One of the most popular and best-studied pathogenic functions for membrane vesicles is to serve as natural vehicles for the intercellular transport of virulence factors and other materials directly into host cells. The production of OM vesicles has been identified as an independent bacterial stress response pathway that is activated when bacteria encounter environmental stress, such as what might be experienced during the colonization of host tissues. Their detection in infected human tissues reinforces this theory. Various other virulence factors are also associated with OM vesicles, including adhesins and degradative enzymes. As a result, OM vesicles are heavily laden with pathogen-associated molecular patterns (PAMPs), virulence factors, and other OM components that can impact the course of infection by having toxigenic effects or by the activation of the innate immune response. However, infected hosts can also benefit from OM vesicle production by stimulating their ability to mount an effective defense. Vesicles display antigens and can elicit potent inflammatory and immune responses. In sum, OM vesicles are likely to play a significant role in the virulence of Gram-negative bacterial pathogens.

scholarly journals The Enolase of Borrelia burgdorferi Is a Plasminogen Receptor Released in Outer Membrane Vesicles

2011 ◽  
Vol 80 (1) ◽  
pp. 359-368 ◽  
Author(s):  
A. Toledo ◽  
J. L. Coleman ◽  
C. J. Kuhlow ◽  
J. T. Crowley ◽  
J. L. Benach
Keyword(s):  
Lyme Disease ◽  
Membrane Proteins ◽  
Borrelia Burgdorferi ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Proteinase K ◽  
Dependent Manner ◽  
Content Type

ABSTRACTThe agent of Lyme disease,Borrelia burgdorferi, has a number of outer membrane proteins that are differentially regulated during its life cycle. In addition to their physiological functions in the organism, these proteins also likely serve different functions in invasiveness and immune evasion. In borreliae, as well as in other bacteria, a number of membrane proteins have been implicated in binding plasminogen. The activation and transformation of plasminogen into its proteolytically active form, plasmin, enhances the ability of the bacteria to disseminate in the host. Outer membrane vesicles ofB. burgdorfericontain enolase, a glycolytic-cycle enzyme that catalyzes 2-phosphoglycerate to form phosphoenolpyruvate, which is also a known plasminogen receptor in Gram-positive bacteria. The enolase was cloned, expressed, purified, and used to generate rabbit antienolase serum. The enolase binds plasminogen in a lysine-dependent manner but not through ionic interactions. Although it is present in the outer membrane, microscopy and proteinase K treatment showed that enolase does not appear to be exposed on the surface. However, enolase in the outer membrane vesicles is accessible to proteolytic degradation by proteinase K. Samples from experimentally and tick-infected mice and rabbits as well as from Lyme disease patients exhibit recognition of enolase in serologic assays. Thus, this immunogenic plasminogen receptor released in outer membrane vesicles could be responsible for external proteolysis in the pericellular environment and have roles in nutrition and in enhancing dissemination.

scholarly journals LptO (PG0027) Is Required for Lipid A 1-Phosphatase Activity in Porphyromonas gingivalis W50

2017 ◽  
Vol 199 (11) ◽  
Author(s):  
Minnie Rangarajan ◽  
Joseph Aduse-Opoku ◽  
Ahmed Hashim ◽  
Graham McPhail ◽  
Zofia Luklinska ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Phosphatase Activity ◽  
Porphyromonas Gingivalis ◽  
Virulence Factors ◽  
Lipid A ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Content Type ◽  
Maldi Tof ◽  
Mutant Strains

ABSTRACT Porphyromonas gingivalis produces outer membrane vesicles (OMVs) rich in virulence factors, including cysteine proteases and A-LPS, one of the two lipopolysaccharides (LPSs) produced by this organism. Previous studies had suggested that A-LPS and PG0027, an outer membrane (OM) protein, may be involved in OMV formation. Their roles in this process were examined by using W50 parent and the ΔPG0027 mutant strains. Inactivation of PG0027 caused a reduction in the yield of OMVs. Lipid A from cells and OMVs of P. gingivalis W50 and the ΔPG0027 mutant strains were analyzed by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Lipid A from W50 cells contained bis-P-pentaacyl, mono-P-pentaacyl, mono-P-tetraacyl, non-P-pentaacyl, and non-P-tetraacyl species, whereas lipid A from ΔPG0027 mutant cells contained only phosphorylated species; nonphosphorylated species were absent. MALDI-TOF/TOF tandem MS of mono-P-pentaacyl (m/z 1,688) and mono-P-tetraacyl (m/z 1,448) lipid A from ΔPG0027 showed that both contained lipid A 1-phosphate, suggesting that the ΔPG0027 mutant strain lacked lipid A 1-phosphatase activity. The total phosphatase activities in the W50 and the ΔPG0027 mutant strains were similar, whereas the phosphatase activity in the periplasm of the ΔPG0027 mutant was lower than that in W50, supporting a role for PG0027 in lipid A dephosphorylation. W50 OMVs were enriched in A-LPS, and its lipid A did not contain nonphosphorylated species, whereas lipid A from the ΔPG0027 mutant (OMVs and cells) contained similar species. Thus, OMVs in P. gingivalis are apparently formed in regions of the OM enriched in A-LPS devoid of nonphosphorylated lipid A. Conversely, dephosphorylation of lipid A through a PG0027-dependent process is required for optimal formation of OMVs. Hence, the relative proportions of nonphosphorylated and phosphorylated lipid A appear to be crucial for OMV formation in this organism. IMPORTANCE Gram-negative bacteria produce outer membrane vesicles (OMVs) by “blebbing” of the outer membrane (OM). OMVs can be used offensively as delivery systems for virulence factors and defensively to aid in the colonization of a host and in the survival of the bacterium in hostile environments. Earlier studies using the oral anaerobe Porphyromonas gingivalis as a model organism to study the mechanism of OMV formation suggested that the OM protein PG0027 and one of the two lipopolysaccharides (LPSs) synthesized by this organism, namely, A-LPS, played important roles in OMV formation. We suggest a novel mechanism of OMV formation in P. gingivalis involving dephosphorylation of lipid A of A-LPS controlled/regulated by PG0027, which causes destabilization of the OM, resulting in blebbing and generation of OMVs.

scholarly journals Identification and Characterization of Outer Membrane Vesicle-Associated Proteins in Salmonella enterica Serovar Typhimurium

2014 ◽  
Vol 82 (10) ◽  
pp. 4001-4010 ◽  
Author(s):  
Jaewoo Bai ◽  
Seul I Kim ◽  
Sangryeol Ryu ◽  
Hyunjin Yoon
Keyword(s):  
Outer Membrane ◽  
Virulence Factors ◽  
Salmonella Enterica ◽  
Minimal Medium ◽  
Environmental Changes ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Associated Proteins

ABSTRACTSalmonella entericaserovar Typhimurium is a primary cause of enteric diseases and has acquired a variety of virulence factors during its evolution into a pathogen. Secreted virulence factors interact with commensal flora and host cells and enableSalmonellato survive and thrive in hostile environments. Outer membrane vesicles (OMVs) released from many Gram-negative bacteria function as a mechanism for the secretion of complex mixtures, including virulence factors. We performed a proteomic analysis of OMVs that were isolated under standard laboratory and acidic minimal medium conditions and identified 14 OMV-associated proteins that were observed in the OMV fraction isolated only under the acidic minimal medium conditions, which reproduced the nutrient-deficient intracellular milieu. The inferred roles of these 14 proteins were diverse, including transporter, enzyme, and transcriptional regulator. The absence of these proteins influencedSalmonellasurvival inside murine macrophages. Eleven of these proteins were predicted to possess secretion signal sequences at their N termini, and three (HupA, GlnH, and PhoN) of the proteins were found to be translocated into the cytoplasm of host cells. The comparative proteomic profiling of OMVs performed in this study revealed different protein compositions in the OMVs isolated under the two different conditions, which indicates that the OMV cargo depends on the growth conditions and provides a deeper insight into howSalmonellautilizes OMVs to adapt to environmental changes.

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