The Role of Membrane Vesicles in Secretion ofLysobactersp. Bacteriolytic Enzymes

2013 ◽  
Vol 23 (1-2) ◽  
pp. 142-151 ◽  
Author(s):  
Natalia V. Vasilyeva ◽  
Irina M. Tsfasman ◽  
Irina V. Kudryakova ◽  
Natalia E. Suzina ◽  
Nina A. Shishkova ◽  
...  
Keyword(s):  
Membrane Vesicles ◽  
Bacteriolytic Enzymes

scholarly journals Primary and Memory Response of Human Monocytes to Vaccines: Role of Nanoparticulate Antigens in Inducing Innate Memory

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 931
Author(s):  
Mayra M. Ferrari Ferrari Barbosa ◽  
Alex Issamu Kanno ◽  
Leonardo Paiva Farias ◽  
Mariusz Madej ◽  
Gergö Sipos ◽  
...  
Keyword(s):  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Innate Immune ◽  
Soluble Form ◽  
Neisseria Lactamica ◽  
Particulate Form ◽  
Future Challenges ◽  
Monocytes And Macrophages

Innate immune cells such as monocytes and macrophages are activated in response to microbial and other challenges and mount an inflammatory defensive response. Exposed cells develop the so-called innate memory, which allows them to react differently to a subsequent challenge, aiming at better protection. In this study, using human primary monocytes in vitro, we have assessed the memory-inducing capacity of two antigenic molecules of Schistosoma mansoni in soluble form compared to the same molecules coupled to outer membrane vesicles of Neisseria lactamica. The results show that particulate challenges are much more efficient than soluble molecules in inducing innate memory, which is measured as the production of inflammatory and anti-inflammatory cytokines (TNFα, IL-6, IL-10). Controls run with LPS from Klebsiella pneumoniae compared to the whole bacteria show that while LPS alone has strong memory-inducing capacity, the entire bacteria are more efficient. These data suggest that microbial antigens that are unable to induce innate immune activation can nevertheless participate in innate activation and memory when in a particulate form, which is a notion that supports the use of nanoparticulate antigens in vaccination strategies for achieving adjuvant-like effects of innate activation as well as priming for improved reactivity to future challenges.

scholarly journals Metagenomic Profiling of Fecal-Derived Bacterial Membrane Vesicles in Crohn’s Disease Patients

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2795
Author(s):  
Nader Kameli ◽  
Heike E. F. Becker ◽  
Tessa Welbers ◽  
Daisy M. A. E. Jonkers ◽  
John Penders ◽  
...  
Keyword(s):  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Membrane Vesicles ◽  
Amplicon Sequencing ◽  
Size Exclusion ◽  
Bacterial Membrane ◽  
Microbial Composition ◽  
Fecal Samples ◽  
Exclusion Chromatography

Background: In the past, many studies suggested a crucial role for dysbiosis of the gut microbiota in the etiology of Crohn’s disease (CD). However, despite being important players in host–bacteria interaction, the role of bacterial membrane vesicles (MV) has been largely overlooked in the pathogenesis of CD. In this study, we addressed the composition of the bacterial and MV composition in fecal samples of CD patients and compared this to the composition in healthy individuals. Methods: Fecal samples from six healthy subjects (HC) in addition to twelve CD patients (six active, six remission) were analyzed in this study. Fecal bacterial membrane vesicles (fMVs) were isolated by a combination of ultrafiltration and size exclusion chromatography. DNA was obtained from the fMV fraction, the pellet of dissolved feces as bacterial DNA (bDNA), or directly from feces as fecal DNA (fDNA). The fMVs were characterized by nanoparticle tracking analysis and cryo-electron microscopy. Amplicon sequencing of 16s rRNA V4 hypervariable gene regions was conducted to assess microbial composition of all fractions. Results: Beta-diversity analysis showed that the microbial community structure of the fMVs was significantly different from the microbial profiles of the fDNA and bDNA. However, no differences were observed in microbial composition between fDNA and bDNA. The microbial richness of fMVs was significantly decreased in CD patients compared to HC, and even lower in active patients. Profiling of fDNA and bDNA demonstrated that Firmicutes was the most dominant phylum in these fractions, while in fMVs Bacteroidetes was dominant. In fMV, several families and genera belonging to Firmicutes and Proteobacteria were significantly altered in CD patients when compared to HC. Conclusion: The microbial alterations of MVs in CD patients particularly in Firmicutes and Proteobacteria suggest a possible role of MVs in host-microbe symbiosis and induction or progression of inflammation in CD pathogenesis. Yet, the exact role for these fMV in the pathogenesis of the disease needs to be elucidated in future studies.

scholarly journals Mutations in the Bacillus thuringiensis Cry1Ca toxin demonstrate the role of domains II and III in specificity towards Spodoptera exigua larvae

2004 ◽  
Vol 384 (3) ◽  
pp. 507-513 ◽  
Author(s):  
Salvador HERRERO ◽  
Joel GONZÁLEZ-CABRERA ◽  
Juan FERRÉ ◽  
Petra L. BAKKER ◽  
Ruud A. de MAAGD
Keyword(s):  
Bacillus Thuringiensis ◽  
Spodoptera Exigua ◽  
Brush Border Membrane ◽  
Specific Activity ◽  
Membrane Vesicles ◽  
Wild Type ◽  
Oligomeric Form ◽  
Specific Receptors ◽  
Domain Iii

Several mutants of the Bacillus thuringiensis Cry1Ca toxin affected with regard to specific activity towards Spodoptera exigua were studied. Alanine was used to replace single residues in loops 2 and 3 of domain II (mutant pPB19) and to replace residues 541–544 in domain III (mutant pPB20). Additionally, a Cry1Ca mutant combining all mutations was constructed (mutant pPB21). Toxicity assays showed a marked decrease in toxicity against S. exigua for all mutants, while they retained their activity against Manduca sexta, confirming the importance of these residues in determining insect specificity. Parameters for binding to the specific receptors in BBMV (brush border membrane vesicles) of S. exigua were determined for all toxins. Compared with Cry1Ca, the affinity of mutant pPB19 was slightly affected (2-fold lower), whereas the affinity of the mutants with an altered domain III (pPB20 and pPB21) was approx. 8-fold lower. Activation of Cry1Ca protoxin by incubation with S. exigua or M. sexta BBMV revealed the transient formation of an oligomeric form of Cry1Ca. The presence of this oligomeric form was tested in the activation of the different Cry1Ca mutants, and we found that those mutated in domain II (pPB19 and pPB21) could not generate the oligomeric form when activated by S. exigua BBMV. In contrast, when oligomerization was tested using BBMV prepared from M. sexta, all of the Cry1Ca mutants showed the formation of a similar oligomeric form as did the wild-type toxin. Our results show how modification of insect specificity can be achieved by manipulation of different parts of the toxin structure involved in different steps of the mode of action of B. thuringiensis toxins.

Abstract 210: αMyHC-mCherry-LC3 Transgenic Mice is a New and Useful Tool to Examine the Role of Autophagy in Cardiomyocytes

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Mai Terada ◽  
Kiyoshi Nobori ◽  
Yoshiko Munehisa ◽  
Manabu Kakizaki ◽  
Takayoshi Ohba ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Heart Diseases ◽  
Hydrolytic Enzymes ◽  
Smooth Muscles ◽  
Membrane Vesicles ◽  
Double Positive ◽  
Intracellular Process ◽  
Fluorescence Protein ◽  
And Function

Autophagy is an intracellular process in which proteins and organelles are transported in double-membrane vesicles called autophagosomes through the cytoplasm to lysosomes for degradation. The autophagosome acquires hydrolytic enzymes by fusing with the lysosome to generate an autolysosome. Constitutive autophagy in the heart under baseline conditions is a homeostatic mechanism for maintaining cardiomyocyte size and global cardiac structure and function. Upregulation of autophagy in various heart diseases, including cardiac hypertrophy and heart failure, is an adaptive response for protecting cells from hemodynamic stress. However, the detailed roles of autophagy in the heart remain unclear. LC3 is localized on the autophagosome membrane. Exogenously expressed GFP fused to LC3 (GFP-LC3) serves as an ideal molecular marker for autophagosome. Transgenic mice expressing GFP-LC3 (CAG-GFP-LC3) have been used to detect autophagy systemically. However, CAG-GFP-LC3 mice cannot distinguish autophagy-positive cardiomyocytes from other cells such as fibroblasts and smooth muscles in the heart and cannot detect autolysosome because GFP-LC3 loses fluorescence due to lysosomal acidic and degradative conditions. To resolve these problems, we have generated transgenic mice (αMyHC-mCherry-LC3) expressing mCherry fused to LC3 under the control of αmyosin heavy chain promoter instead of CAG promoter to detect autophagy only in cardiomyocytes. mCherry is an improved-monomeric red-fluorescence protein and does not lose fluorescence under acidic condition. Thus, αMyHC-mCherry-LC3 mice can detect not only autophagosome before fusion with lysosome but also autophagosome after fusion with lysosome. Moreover, we have crossed αMyHC-mCherry-LC3 mice with CAG-GFP-LC3 mice. Green signals showed autophagosome in non-cardiomyocytes. On the other hand, red signals showed autolysosome and double positive signals showed autophagosome in cardiacmyocytes. In conclusion, we have generated αMyHC-mCherry-LC3 mice to detect both autophagosome and autolysosome. The double transgenic mice cannot only detect autophagosome and autolysosome but also distinguish between them. This is an innovative method to examine the role of autophagy in cardiomyocytes.

scholarly journals Extracellular Vesicles in the Pathogenesis of Viral Infections in Humans

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1200 ◽  
Author(s):  
Allen Caobi ◽  
Madhavan Nair ◽  
Andrea D. Raymond
Keyword(s):  
Extracellular Vesicles ◽  
Viral Infections ◽  
Membrane Vesicles ◽  
Response Modulation ◽  
Viral Spread ◽  
Neurotropic Viruses ◽  
Immunodeficiency Virus ◽  
Immune Response Modulation ◽  
Potential Use

Most cells can release extracellular vesicles (EVs), membrane vesicles containing various proteins, nucleic acids, enzymes, and signaling molecules. The exchange of EVs between cells facilitates intercellular communication, amplification of cellular responses, immune response modulation, and perhaps alterations in viral pathogenicity. EVs serve a dual role in inhibiting or enhancing viral infection and pathogenesis. This review examines the current literature on EVs to explore the complex role of EVs in the enhancement, inhibition, and potential use as a nanotherapeutic against clinically relevant viruses, focusing on neurotropic viruses: Zika virus (ZIKV) and human immunodeficiency virus (HIV). Overall, this review’s scope will elaborate on EV-based mechanisms, which impact viral pathogenicity, facilitate viral spread, and modulate antiviral immune responses.

Folate transport by human intestinal brush-border membrane vesicles

1987 ◽  
Vol 252 (2) ◽  
pp. G229-G236 ◽  
Author(s):  
H. M. Said ◽  
F. K. Ghishan ◽  
R. Redha
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Disulfonic Acid ◽  
Folate Transport ◽  
Intestinal Brush Border Membrane ◽  
Transport Carrier ◽  
Incubation Buffer

Transport of folic acid (Pte-Glu) across the brush-border membrane of human intestine was studied using brush-border membrane vesicle (BBMV) technique. The transport of Pte-Glu was higher in BBMV prepared from the jejunum than those prepared from the ileum (0.70 +/- 0.05 and 0.14 +/- 0.02 pmol X mg protein-1 X 10 s-1, respectively). The transport of Pte-Glu appeared to be carrier mediated and was pH dependent and increased with decreasing incubation buffer pH; saturable (Kt = 1.69 microM, Vmax = 4.72 pmol X mg protein-1 X 10 s-1); inhibited in a competitive manner by the structural analogues 5-methyltetrahydrofolate, methotrexate, and 5-formyltetrahydrofolate (Ki = 2.2, 1.4 and 1.4 microM, respectively); not affected by inducing a relatively positive or negative intravesicular compartment; independent of Na+ gradient; and inhibited by 4,4'-diisothiocyanatostlibene-2,2'-disulfonic acid (DIDS), an anion exchange inhibitor. The increase in Pte-Glu transport on decreasing incubation buffer pH appeared to be in part mediated through a direct effect of acidic pH on the transport carrier and in part through the pH gradient imposed by activating Pte-Glu-:OH- exchange and/or Pte-Glu-:H+ co-transport mechanisms. The important role of an acidic extravesicular environment in Pte-Glu transport is consistent with a role for the intestinal surface acid microclimate in folate transport. These results demonstrate that Pte-Glu transport in human BBMV occurs by a carrier-mediated system that is similar to that described for rat and rabbit intestinal BBMV.

scholarly journals The Mutation of Conservative Asp268 Residue in the Peptidoglycan-Associated Domain of the OmpA Protein Affects Multiple Acinetobacter baumannii Virulence Characteristics

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1972 ◽  
Author(s):  
Jūratė Skerniškytė ◽  
Emilija Karazijaitė ◽  
Julien Deschamps ◽  
Renatas Krasauskas ◽  
Romain Briandet ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Protein A ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Clinical Strain ◽  
Infection Model ◽  
Terminal Domain ◽  
Ompa Protein

Acinetobacter baumannii is a nosocomial human pathogen of increasing concern due to its multidrug resistance profile. The outer membrane protein A (OmpA) is an abundant bacterial cell surface component involved in A. baumannii pathogenesis. It has been shown that the C-terminal domain of OmpA is located in the periplasm and non-covalently associates with the peptidoglycan layer via two conserved amino acids, thereby anchoring OmpA to the cell wall. Here, we investigated the role of one of the respective residues, D268 in OmpA of A. baumannii clinical strain Ab169, on its virulence characteristics by complementing the ΔompA mutant with the plasmid-borne ompAD268A allele. We show that while restoring the impaired biofilm formation of the ΔompA strain, the Ab169ompAD268A mutant tended to form bacterial filaments, indicating the abnormalities in cell division. Moreover, the Ab169 OmpA D268-mediated association to peptidoglycan was required for the manifestation of twitching motility, desiccation resistance, serum-induced killing, adhesion to epithelial cells and virulence in a nematode infection model, although it was dispensable for the uptake of β-lactam antibiotics by outer membrane vesicles. Overall, the results of this study demonstrate that the OmpA C-terminal domain-mediated association to peptidoglycan is critical for a number of virulent properties displayed by A. baumannii outside and within the host.

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