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Outer membrane vesicles

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https://www.readbyqxmd.com/read/28434130/characterization-of-extracellular-membrane-vesicles-of-an-antarctic-bacterium-shewanella-livingstonensis-ac10-and-their-enhanced-production-by-alteration-of-phospholipid-composition
#1
Fumiaki Yokoyama, Jun Kawamoto, Tomoya Imai, Tatsuo Kurihara
A cold-adapted bacterium, Shewanella livingstonensis Ac10, which produces eicosapentaenoic acid (EPA) as a component of its membrane phospholipids, is useful as a model to study the function of EPA and as a host for heterologous production of thermolabile proteins at low temperatures. In this study, we characterized extracellular membrane vesicles (EMVs) of this bacterium to examine the involvement of EPA in the biogenesis of EMVs and for the future application of EMVs to extracellular protein production. We found that this strain produced EMVs from the cell surface...
April 22, 2017: Extremophiles: Life Under Extreme Conditions
https://www.readbyqxmd.com/read/28434115/interaction-of-selected-phenylpropenes-with-dipalmitoylphosphatidylcholine-membrane-and-their-relevance-to-antibacterial-activity
#2
Riham Gharib, Amal Najjar, Lizette Auezova, Catherine Charcosset, Hélène Greige-Gerges
The effect of structurally closely related phenylpropenes (PPs), estragole, anethole, eugenol, and isoeugenol, on the fluidity of dipalmitoyl phosphatidyl choline (DPPC) liposome membrane was investigated by DSC, Raman, and fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH). Liposomes were prepared by thin-film hydration method at various DPPC:PP molar ratios. The DPH anisotropy measurements of blank and PP-loaded liposomes were performed at 28, 41, and 50 °C, which correspond, respectively, to gel phase, main transition temperature of DPPC, and liquid phase...
April 22, 2017: Journal of Membrane Biology
https://www.readbyqxmd.com/read/28430970/helicobacter-pylori-outer-membrane-vesicles-inhibit-human-t-cell-responses-via-induction-of-monocyte-cox-2-expression
#3
Barry D Hock, Judith L McKenzie, Jacqueline I Keenan
The modulation of T cell responses by Helicobacter pylori is thought to potentiate both H. pylori persistence and development of gastric pathologies including cancer. Release of outer membrane vesicles (OMV) by H. pylori provides a potential vehicle for modulation of the immune system. Although OMV are thought to have T cell suppressive activity this has not yet been demonstrated. Their suppressive activity was investigated in this study using the responses of peripheral blood mononuclear cells (PBMC) to T cell stimuli as a readout...
April 18, 2017: Pathogens and Disease
https://www.readbyqxmd.com/read/28421662/the-outer-membrane-vesicles-secretion-system-type-zero
#4
REVIEW
Andrea Guerrero-Mandujano, Cecilia Hernández-Cortez, J Antonio Ibarra, Graciela Castro-Escarpulli
Gram-negative bacteria have mechanisms through which they can colonize and survive in different environments, such as the secretion systems types (1-6) that have been widely studied and characterized. Nowadays, some authors have proposed extracellular structures, such as the outer membrane vesicles, to be considered as an additional and independent secretion system. The outer membrane vesicles are spherical particles of 50-250 nm in diameter; they originate in the outer membrane, therefore, they have a very similar composition to the latter...
April 19, 2017: Traffic
https://www.readbyqxmd.com/read/28416709/spheres-of-hope-packets-of-doom-the-good-and-bad-of-outer-membrane-vesicles-in-interspecies-and-ecological-dynamics
#5
Jonathan B Lynch, Rosanna A Alegado
Outer membrane vesicles (OMVs) are proteoliposome nanoparticles ubiquitously produced by Gram-negative bacteria. Typically bearing similar composition to the outer membrane and periplasm of the cells from which they are derived, OMVs package an array of proteins, lipids, and nucleic acids. Once considered inconsequential byproducts of bacterial growth, OMVs have since been demonstrated to mediate cellular stress relief, promote horizontal gene transfer and antimicrobial activity, and elicit metazoan inflammation...
April 17, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28413119/the-two-dictyostelium-discoideum-autophagy-8-proteins-have-distinct-autophagic-functions
#6
Susanne Meßling, Jan Matthias, Qiuhong Xiong, Sarah Fischer, Ludwig Eichinger
Autophagy is a highly conserved cellular degradation pathway which is crucial for various cellular processes. The autophagic process is subdivided in the initiation, autophagosome maturation and lysosomal degradation phases and involves more than forty core and accessory autophagy-related (ATG) proteins. Autophagy 8 (ATG8, in mammals LC3) is a well-established marker of autophagy and is linked to the autophagic membrane from initiation until fusion with the lysosome. We generated single and double knock-out mutants of the two Dictyostelium paralogues, ATG8a and ATG8b, as well as strains that expressed RFP-ATG8a and/or GFP-ATG8b, RFP-ATG8b, RFP-GFP-ATG8a or RFP-GFP-ATG8b in different knock-out mutants...
April 4, 2017: European Journal of Cell Biology
https://www.readbyqxmd.com/read/28409545/high-affinity-caspase-4-binding-to-lps-presented-as-high-molecular-mass-aggregates-or-in-outer-membrane-vesicles
#7
Mark A Wacker, Athmane Teghanemt, Jerrold P Weiss, Jason H Barker
Caspases of the non-canonical inflammasome (caspases -4, -5, and -11) directly bind endotoxin (LOS/LPS) and can be activated in the absence of any co-factors. Models of LPS-induced caspase activation have postulated that 1:1 binding of endotoxin monomers to caspase trigger caspase oligomerization and activation, analogous to that established for endotoxin-induced activation of MD-2/TLR4. However, using metabolically radiolabeled LOS and LPS, we now show high affinity and selective binding of caspase-4 to high molecular mass aggregates of purified endotoxin and to endotoxin-rich outer membrane vesicles without formation of 1:1 endotoxin:caspase complexes...
May 2017: Innate Immunity
https://www.readbyqxmd.com/read/28408867/visualization-of-snare-mediated-hemifusion-between-giant-unilamellar-vesicles-arrested-by-myricetin
#8
Paul Heo, Joon-Bum Park, Yeon-Kyun Shin, Dae-Hyuk Kweon
Neurotransmitters are released within a millisecond after Ca(2+) arrives at an active zone. However, the vesicle fusion pathway underlying this synchronous release is yet to be understood. At the center of controversy is whether hemifusion, in which outer leaflets are merged while inner leaflets are still separated, is an on-pathway or off-pathway product of Ca(2+)-triggered exocytosis. Using the single vesicle fusion assay, we recently demonstrated that hemifusion is an on-pathway intermediate that immediately proceeds to full fusion upon Ca(2+) triggering...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28396597/photoreceptor-outer-segment-like-structures-in-long-term-3d-retinas-from-human-pluripotent-stem-cells
#9
Karl J Wahlin, Julien A Maruotti, Srinivasa R Sripathi, John Ball, Juan M Angueyra, Catherine Kim, Rhonda Grebe, Wei Li, Bryan W Jones, Donald J Zack
The retinal degenerative diseases, which together constitute a leading cause of hereditary blindness worldwide, are largely untreatable. Development of reliable methods to culture complex retinal tissues from human pluripotent stem cells (hPSCs) could offer a means to study human retinal development, provide a platform to investigate the mechanisms of retinal degeneration and screen for neuroprotective compounds, and provide the basis for cell-based therapeutic strategies. In this study, we describe an in vitro method by which hPSCs can be differentiated into 3D retinas with at least some important features reminiscent of a mature retina, including exuberant outgrowth of outer segment-like structures and synaptic ribbons, photoreceptor neurotransmitter expression, and membrane conductances and synaptic vesicle release properties consistent with possible photoreceptor synaptic function...
April 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28386629/an-in-vitro-study-of-the-antioxidant-and-antihemolytic-properties-of-buddleja-globosa-matico
#10
Mario Suwalsky, José Duguet, Hernán Speisky
The antioxidant and antihemolytic properties contained in the leaves of Buddleja globosa (B. globosa), also known as "Matico," were determined. Aqueous extracts of leaves were assayed in human erythrocytes and molecular models of its membrane. The latter were bilayers built-up of lipids located in the outer and inner leaflets of the erythrocyte membrane. Observations by scanning electron microscopy showed that the extract altered the morphology of erythrocytes inducing the formation of crenated echinocytes...
April 6, 2017: Journal of Membrane Biology
https://www.readbyqxmd.com/read/28381971/joint-small-angle-x-ray-and-neutron-scattering-data-analysis-of-asymmetric-lipid-vesicles
#11
Barbara Eicher, Frederick A Heberle, Drew Marquardt, Gerald N Rechberger, John Katsaras, Georg Pabst
Low- and high-resolution models describing the internal transbilayer structure of asymmetric lipid vesicles have been developed. These models can be used for the joint analysis of small-angle neutron and X-ray scattering data. The models describe the underlying scattering length density/electron density profiles either in terms of slabs or through the so-called scattering density profile, previously applied to symmetric lipid vesicles. Both models yield structural details of asymmetric membranes, such as the individual area per lipid, and the hydrocarbon thickness of the inner and outer bilayer leaflets...
April 1, 2017: Journal of Applied Crystallography
https://www.readbyqxmd.com/read/28381413/photoreceptor-discs-form-through-peripherin-dependent-suppression-of-ciliary-ectosome-release
#12
Raquel Y Salinas, Jillian N Pearring, Jin-Dong Ding, William J Spencer, Ying Hao, Vadim Y Arshavsky
The primary cilium is a highly conserved organelle housing specialized molecules responsible for receiving and processing extracellular signals. A recently discovered property shared across many cilia is the ability to release small vesicles called ectosomes, which are used for exchanging protein and genetic material among cells. In this study, we report a novel role for ciliary ectosomes in building the elaborate photoreceptor outer segment filled with hundreds of tightly packed "disc" membranes. We demonstrate that the photoreceptor cilium has an innate ability to release massive amounts of ectosomes...
April 5, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28371608/studying-factors-involved-in-biogenesis-of-lysobacter-sp-xl1-outer-membrane-vesicles
#13
I V Kudryakova, N E Suzina, N G Vinokurova, N A Shishkova, N V Vasilyeva
The Gram-negative bacterium Lysobacter sp. XL1 produces outer membrane vesicles that are heterogeneous in size, density, and protein composition. One of the subpopulations is secretory vesicles for lytic protease L5 of Lysobacter sp. XL1 (Kudryakova et al. (2015) FEMS Microbiol. Lett., 362, fnv137). Protein L5 was assumed to influence biogenesis of these secretory vesicles that contain it. Using a Pseudomonas fluorescens Q2-87/B expression system, it was shown that the recombinant L5 protein may act as a factor of vesicle biogenesis...
April 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/28369428/novel-approaches-to-neisseria-meningitidis-vaccine-design
#14
Myron Christodoulides, John Heckels
A range of vaccines is available for preventing life-threatening diseases caused by infection with Neisseria meningitidis (meningococcus, Men). Capsule polysaccharide (CPS)-conjugate vaccines are successful prophylactics for serogroup MenA, MenC, MenW and MenY infections and outer membrane vesicle (OMV) vaccines have been used successfully for controlling clonal serogroup MenB infections. MenB vaccines based on recombinant proteins identified by reverse vaccinology (Bexsero®) and proteomics (Trumenba®) approaches have recently been licensed and Bexsero® has been introduced into the UK infant immunization program...
March 22, 2017: Pathogens and Disease
https://www.readbyqxmd.com/read/28368526/licensed-meningococcal-serogroup-b-vaccine-induced-immunity-against-invasive-disease-does-not-reflect-protection-against-nasal-colonization-in-a-humanized-mouse-model
#15
Carolyn M Buckwalter, Elissa G Currie, Raymond S W Tsang, Scott D Gray-Owen
Background: The 4CMenB vaccine is an outer membrane vesicle and recombinant protein-based vaccine recently licensed to protect against serogroup B meningococcal disease. It remains unknown whether this vaccine will prevent carriage or transmission, key aspects in long-term vaccine success and disease eradication. Methods: Employing a 'humanized' transgenic mouse model of nasal colonization, a systematic approach was taken to estimate the potential for carriage prevention against antigenically-diverse Neisseria meningitidis strains, and to compare this protection to an invasive meningococcal disease challenge model...
March 27, 2017: Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28357390/breaking-the-bilayer-omv-formation-during-environmental-transitions
#16
COMMENT
Katherine E Bonnington, Meta J Kuehn
Gram-negative bacteria maintain the barrier properties of the outer membrane (OM) in a wide array of physiological conditions despite their inability to degrade lipopolysaccharide (LPS) and protein material present in the outer leaflet of the OM. Through characterization of the native dynamics of outer membrane LPS change we recently described a mechanism in which these diderm organisms overcome this design flaw. In response to different environmental stimuli Salmonellaenterica modulates the export of specific structural variants of lipid A via outer membrane vesicles (OMVs)...
February 3, 2017: Microbial Cell
https://www.readbyqxmd.com/read/28357362/bacterial-outer-membrane-vesicle-biogenesis-a-new-mechanism-and-its-implications
#17
COMMENT
Sandro Roier, Franz G Zingl, Fatih Cakar, Stefan Schild
Outer membrane vesicle (OMV) release by Gram-negative bacteria has been observed and studied for decades. First considered as a by-product of cell lysis, it soon became evident that OMVs are actively secreted from the outer membrane (OM) of Gram-negative bacteria. Accordingly, these small particles (~ 10-300 nm in diameter) consist mainly of OM components like phospholipids (PLs), OM proteins, and lipopolysaccharides or lipooligosaccharides. However, OMVs may also comprise periplasmic, inner membrane, or cytoplasmic components...
May 10, 2016: Microbial Cell
https://www.readbyqxmd.com/read/28356256/recent-progress-in-the-prevention-of-serogroup-b-meningococcal-disease
#18
Ian M Feavers, Martin C J Maiden
The widespread use of meningococcal polysaccharide conjugate vaccines has highlighted the challenge of providing protection against serogroup B disease. Over a period of four decades vaccine development has focused on sub-capsular, protein antigens, first with outer membrane vesicle (OMV) vaccines against epidemic outbreaks, and more recently on new multicomponent vaccines designed to offer better cross-protection against the antigenically diverse strains responsible for endemic disease. Because of the low incidence of meningococcal disease, the protective efficacy of these vaccines has not been determined in clinical studies and their licensure has been based on serological data; however, the serological assays used to predict protective coverage have limitations...
March 29, 2017: Clinical and Vaccine Immunology: CVI
https://www.readbyqxmd.com/read/28348979/biology-of-acinetobacter-baumannii-pathogenesis-antibiotic-resistance-mechanisms-and-prospective-treatment-options
#19
REVIEW
Chang-Ro Lee, Jung Hun Lee, Moonhee Park, Kwang Seung Park, Il Kwon Bae, Young Bae Kim, Chang-Jun Cha, Byeong Chul Jeong, Sang Hee Lee
Acinetobacter baumannii is undoubtedly one of the most successful pathogens responsible for hospital-acquired nosocomial infections in the modern healthcare system. Due to the prevalence of infections and outbreaks caused by multi-drug resistant A. baumannii, few antibiotics are effective for treating infections caused by this pathogen. To overcome this problem, knowledge of the pathogenesis and antibiotic resistance mechanisms of A. baumannii is important. In this review, we summarize current studies on the virulence factors that contribute to A...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28348410/a-pseudomonas-t6ss-effector-recruits-pqs-containing-outer-membrane-vesicles-for-iron-acquisition
#20
Jinshui Lin, Weipeng Zhang, Juanli Cheng, Xu Yang, Kaixiang Zhu, Yao Wang, Gehong Wei, Pei-Yuan Qian, Zhao-Qing Luo, Xihui Shen
Iron sequestration by host proteins contributes to the defence against bacterial pathogens, which need iron for their metabolism and virulence. A Pseudomonas aeruginosa mutant lacking all three known iron acquisition systems retains the ability to grow in media containing iron chelators, suggesting the presence of additional pathways involved in iron uptake. Here we screen P. aeruginosa mutants defective in growth in iron-depleted media and find that gene PA2374, proximal to the type VI secretion system H3 (H3-T6SS), functions synergistically with known iron acquisition systems...
March 28, 2017: Nature Communications
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