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Type 6 secretion system

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https://www.readbyqxmd.com/read/28821836/porv-is-an-outer-membrane-shuttle-protein-for-the-type-ix-secretion-system
#1
Michelle D Glew, Paul D Veith, Dina Chen, Dhana G Gorasia, Ben Peng, Eric C Reynolds
Porphyromonas gingivalis is a keystone pathogen associated with chronic periodontitis. Major virulence factors named gingipains (cysteine proteinases, RgpA, RgpB and Kgp) are secreted via the Type IX Secretion System (T9SS). These, together with approximately 30 other proteins, are secreted to the cell surface and anchored to the outer membrane by covalent modification to anionic lipopolysaccharide (A-LPS) via the novel Gram negative sortase, PorU. PorU is localised on the cell surface and cleaves the C-terminal domain signal (CTD) of T9SS substrates and conjugates their new C-termini to A-LPS...
August 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28818949/in-situ-architecture-function-and-evolution-of-a-contractile-injection-system
#2
Désirée Böck, João M Medeiros, Han-Fei Tsao, Thomas Penz, Gregor L Weiss, Karin Aistleitner, Matthias Horn, Martin Pilhofer
Contractile injection systems mediate bacterial cell-cell interactions by a bacteriophage tail-like structure. In contrast to extracellular systems, the type 6 secretion system (T6SS) is defined by intracellular localization and attachment to the cytoplasmic membrane. Here we used cryo-focused ion beam milling, electron cryotomography, and functional assays to study a T6SS in Amoebophilus asiaticus The in situ architecture revealed three modules, including a contractile sheath-tube, a baseplate, and an anchor...
August 18, 2017: Science
https://www.readbyqxmd.com/read/28813514/the-helicobacter-pylori-type-iv-secretion-system-promotes-il-8-synthesis-in-a-model-of-pediatric-airway-epithelium-via-p38-map-kinase
#3
Myra G Dela Pena-Ponce, Monica T Jimenez, Lori M Hansen, Jay V Solnick, Lisa A Miller
Epidemiologic studies have reported an inverse relationship between childhood Helicobacter pylori infection and development of allergic asthma. Because lung epithelium plays an important role in allergic asthma pathogenesis, we hypothesized that H. pylori may directly influence airway epithelial cell innate immune function, particularly in early childhood. To test our hypothesis, we established an in vitro H. pylori infection model using primary tracheobronchial epithelial cell cultures derived from infant, juvenile and adult rhesus monkeys...
2017: PloS One
https://www.readbyqxmd.com/read/28808685/structure-of-a-1-5-mda-adhesin-that-binds-its-antarctic-bacterium-to-diatoms-and-ice
#4
Shuaiqi Guo, Corey A Stevens, Tyler D R Vance, Luuk L C Olijve, Laurie A Graham, Robert L Campbell, Saeed R Yazdi, Carlos Escobedo, Maya Bar-Dolev, Victor Yashunsky, Ido Braslavsky, David N Langelaan, Steven P Smith, John S Allingham, Ilja K Voets, Peter L Davies
Bacterial adhesins are modular cell-surface proteins that mediate adherence to other cells, surfaces, and ligands. The Antarctic bacterium Marinomonas primoryensis uses a 1.5-MDa adhesin comprising over 130 domains to position it on ice at the top of the water column for better access to oxygen and nutrients. We have reconstructed this 0.6-μm-long adhesin using a "dissect and build" structural biology approach and have established complementary roles for its five distinct regions. Domains in region I (RI) tether the adhesin to the type I secretion machinery in the periplasm of the bacterium and pass it through the outer membrane...
August 2017: Science Advances
https://www.readbyqxmd.com/read/28808000/vibrio-cholerae-type-6-secretion-system-effector-trafficking-in-target-bacterial-cells
#5
Brian T Ho, Yang Fu, Tao G Dong, John J Mekalanos
The type 6 secretion system (T6SS) is used by many Gram-negative bacterial species to deliver toxic effector proteins into nearby bacteria prey cells to kill or inhibit their growth. VgrG proteins are core conserved secretion substrates of the T6SS and one subset of T6SS effectors consists of VgrG proteins with C-terminal extension domains carrying various enzymatic activities. In Vibrio cholerae, VgrG3 has a hydrolase extension domain and degrades peptidoglycan in the periplasm of target bacteria. In this study, we replaced this domain with a nuclease domain from Salmonella enterica subsp...
August 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28802275/response-of-methylocystis-sp-strain-sc2-to-salt-stress-physiology-global-transcriptome-and-amino-acid-profiles
#6
Dongfei Han, Hannes Link, Werner Liesack
Soil microorganisms have to rapidly respond to salt-induced osmotic stress. Type II methanotrophs of the genus Methylocystis are widely distributed in upland soils, but are known to have a low salt tolerance. Here, we tested the ability of Methylocystis sp. strain SC2 to adapt to increased salinity. When exposed to 0.75% NaCl, methane oxidation was completely inhibited for 2.25 h and fully recovered within 6 h. Growth was inhibited for 23.5 h and then fully recovered. Its transcriptome was profiled after 0 min (control), 45 min (early response) and 14 h (late response) of stress exposure...
August 11, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28792376/construction-of-an-inactivated-typhoid-vaccine-candidate-expressing-escherichia-coli-heat-labile-enterotoxin-b-subunit-and-evaluation-of-its-immunogenicity-in-a-murine-model
#7
Boram Kim, Gayeon Won, John Hwa Lee
PURPOSE: Typhoid fever caused by Salmonella enterica serovar Typhi has contributed to the global public health burden, particularly in developing countries. In this study, an S. Typhi ghost was developed and its capacity as a vaccine candidate against typhoid fever was assessed. METHODOLOGY: An asd+ plasmid pJHL187 harbouring a ghost cassette comprising the PhiX 174 Elysis gene tightly controlled under the convergent promotor system was transformed into an asd gene-deleted mutant S...
August 10, 2017: Journal of Medical Microbiology
https://www.readbyqxmd.com/read/28790180/pseudomonas-aeruginosa-lasb-protease-impairs-innate-immunity-in-mice-and-humans-by-targeting-a-lung-epithelial-cystic-fibrosis-transmembrane-regulator-il-6-antimicrobial-repair-pathway
#8
Vinciane Saint-Criq, Bérengère Villeret, Fabien Bastaert, Saadé Kheir, Aurélie Hatton, Aurélie Cazes, Zhou Xing, Isabelle Sermet-Gaudelus, Ignacio Garcia-Verdugo, Aleksander Edelman, Jean-Michel Sallenave
BACKGROUND: Pseudomonas aeruginosa lung infections are a huge problem in ventilator-associated pneumonia, cystic fibrosis (CF) and in chronic obstructive pulmonary disease (COPD) exacerbations. This bacterium secretes virulence factors that may subvert host innate immunity. OBJECTIVE: We evaluated the effect of P. aeruginosa elastase LasB, an important virulence factor secreted by the type II secretion system, on ion transport, innate immune responses and epithelial repair, both in vitro and in vivo...
August 8, 2017: Thorax
https://www.readbyqxmd.com/read/28782757/osthole-treatment-ameliorates-th2-mediated-allergic-asthma-and-exerts-immunomodulatory-effects-on-dendritic-cell-maturation-and-function
#9
Chen-Yuan Chiang, Chen-Chen Lee, Chia-Kwung Fan, Huei-Mei Huang, Bor-Luen Chiang, Yueh-Lun Lee
Osthole, an active component of Chinese herbal medicines, reportedly possesses various pharmacological properties and has potential therapeutic applications. This study explored the anti-allergic effects of osthole in asthmatic mice and investigated the immunomodulatory actions of osthole on dendritic cells (DCs) and T cells. Herein, we show that oral administration of osthole to BALB/c mice after ovalbumin (OVA) sensitization ameliorated all of the cardinal features of T helper 2 (Th2)-mediated allergic asthma; namely, the production of OVA-specific immunoglobulin E, airway hyperresponsiveness, airway inflammation and the production of Th2-type cytokines including interleukin (IL)-4, IL-5 and IL-13...
August 7, 2017: Cellular & Molecular Immunology
https://www.readbyqxmd.com/read/28781075/activated-tissue-resident-mesenchymal-stromal-cells-regulate-natural-killer-cell-immune-and-tissue-regenerative-function
#10
Robert Michael Petri, Alexander Hackel, Katrin Hahnel, Claudia Alexandra Dumitru, Kirsten Bruderek, Stefanie B Flohe, Annette Paschen, Stephan Lang, Sven Brandau
The interaction of mesenchymal stromal cells (MSCs) with natural killer (NK) cells is traditionally thought of as a static inhibitory model, whereby resting MSCs inhibit NK cell effector function. Here, we use a dynamic in vitro system of poly(I:C) stimulation to model the interaction of NK cells and tissue-resident MSCs in the context of infection or tissue injury. The experiments suggest a time-dependent system of regulation and feedback, where, at early time points, activated MSCs secrete type I interferon to enhance NK cell effector function, while at later time points TGF-β and IL-6 limit NK cell effector function and terminate inflammatory responses by induction of a regulatory senescent-like NK cell phenotype...
July 24, 2017: Stem Cell Reports
https://www.readbyqxmd.com/read/28777089/crystal-structure-of-the-putative-cytoplasmic-protein-stm0279-hcp2-from-salmonella-typhimurium
#11
Qing Peng Lin, Zeng Qiang Gao, Zhi Geng, Heng Zhang, Yu Hui Dong
STM0279 is a putative cytoplasmic protein from Salmonella typhimurium and was recently renamed haemolysin co-regulated protein 2 (Hcp2), with the neighbouring STM0276 being Hcp1. Both of them are encoded by the type VI secretion system (T6SS) of the Salmonella pathogenicity island 6 (SPI-6) locus and have high sequence identity. The Hcp proteins may function as a vital component of the T6SS nanotube and as a transporter and chaperone of diverse effectors from the bacterial T6SS. In this study, the crystal structure and the oligomeric state in solution of Hcp2 from S...
August 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/28745328/diacylglycerol-kinase-synthesized-by-commensal-lactobacillus-reuteri-diminishes-protein-kinase-c-phosphorylation-and-histamine-mediated-signaling-in-the-mammalian-intestinal-epithelium
#12
B P Ganesh, A Hall, S Ayyaswamy, J W Nelson, R Fultz, A Major, A Haag, M Esparza, M Lugo, S Venable, M Whary, J G Fox, J Versalovic
Lactobacillus reuteri 6475 (Lr) of the human microbiome synthesizes histamine and can suppress inflammation via type 2 histamine receptor (H2R) activation in the mammalian intestine. Gut microbes such as Lr promote H2R signaling and may suppress H1R proinflammatory signaling pathways in parallel by unknown mechanisms. In this study, we identified a soluble bacterial enzyme known as diacylglycerol kinase (Dgk) from Lr that is secreted into the extracellular milieu and presumably into the intestinal lumen. DgK diminishes diacylglycerol (DAG) quantities in mammalian cells by promoting its metabolic conversion and causing reduced protein kinase C phosphorylation (pPKC) as a net effect in mammalian cells...
July 26, 2017: Mucosal Immunology
https://www.readbyqxmd.com/read/28704555/a-system-model-of-the-effects-of-exercise-on-plasma-interleukin-6-dynamics-in-healthy-individuals-role-of-skeletal-muscle-and-adipose-tissue
#13
Micaela Morettini, Maria Concetta Palumbo, Massimo Sacchetti, Filippo Castiglione, Claudia Mazzà
Interleukin-6 (IL-6) has been recently shown to play a central role in glucose homeostasis, since it stimulates the production and secretion of Glucagon-like Peptide-1 (GLP-1) from intestinal L-cells and pancreas, leading to an enhanced insulin response. In resting conditions, IL-6 is mainly produced by the adipose tissue whereas, during exercise, skeletal muscle contractions stimulate a marked IL-6 secretion as well. Available mathematical models describing the effects of exercise on glucose homeostasis, however, do not account for this IL-6 contribution...
2017: PloS One
https://www.readbyqxmd.com/read/28703796/p75-ntr-antagonists-attenuate-photoreceptor-cell-loss-in-murine-models-of-retinitis-pigmentosa
#14
María Platón-Corchado, Pablo F Barcelona, Sean Jmaeff, Miguel Marchena, Alberto M Hernández-Pinto, Catalina Hernández-Sánchez, H Uri Saragovi, Enrique J de la Rosa
ProNGF signaling through p75(NTR) has been associated with neurodegenerative disorders. Retinitis pigmentosa (RP) comprises a group of inherited retinal dystrophies that causes progressive photoreceptor cell degeneration and death, at a rate dependent on the genetic mutation. There are more than 300 mutations causing RP, and this is a challenge to therapy. Our study was designed to explore a common mechanism for p75(NTR) in the progression of RP, and assess its potential value as a therapeutic target. The proNGF/p75(NTR) system is present in the dystrophic retina of the rd10 RP mouse model...
July 13, 2017: Cell Death & Disease
https://www.readbyqxmd.com/read/28664195/partial-exhaustion-of-cd8-t-cells-and-clinical-response-to-teplizumab-in-new-onset-type-1-diabetes
#15
S Alice Long, Jerill Thorpe, Hannah A DeBerg, Vivian Gersuk, James Eddy, Kristina M Harris, Mario Ehlers, Kevan C Herold, Gerald T Nepom, Peter S Linsley
Biologic treatment of T1D typically results in transient stabilization of C-peptide levels (a surrogate for endogenous insulin secretion) in some patients, followed by progression at the same rate as in untreated control groups. Here, we used integrated systems biology and flow cytometry approaches with clinical trial blood samples to elucidate pathways associated with C-peptide stabilization in T1D subjects treated with the anti-CD3 monoclonal antibody teplizumab. We identified a population of CD8 T cells that accumulated in subjects with the best response to treatment (responders) and showed that these cells phenotypically resembled exhausted T cells by expressing high levels of the transcription factor EOMES, effector molecules, and multiple inhibitory receptors (IRs), including TIGIT and KLRG1...
November 2016: Science Immunology
https://www.readbyqxmd.com/read/28652310/bacterial-nucleotidyl-cyclase-inhibits-host-innate-immune-response-through-suppressing-tak1-activation
#16
Chenxi He, Yilong Zhou, Feng Liu, Haipeng Liu, Hao Tan, Shouguang Jin, Weihui Wu, Baoxue Ge
Exoenzyme Y (ExoY) is a type III secretion system effector found in 90% of the Pseudomonas aeruginosa isolates. Although it is known that ExoY is a soluble nucleotidyl cyclase that increases the cytoplasmic levels of nucleoside 3' , 5' -cyclic monophosphates (cNMPs) to mediate endothelial Tau phosphorylation and permeability, its functional role in the innate immune response is still poorly understood. Transforming growth factor β activated kinase-1 (TAK1) is critical for mediating Toll-like receptor (TLR) signaling and subsequent activation of NF-κB and AP-1, which are transcriptional activators of innate immunity...
June 26, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28650701/prevalence-of-acinetobacter-baumannii-strains-expressing-the-type-6-secretion-system-in-patients-with-bacteremia
#17
Guillermo D Repizo
No abstract text is available yet for this article.
June 26, 2017: Virulence
https://www.readbyqxmd.com/read/28646039/monocyte-adhesion-migration-and-extracellular-matrix-breakdown-are-regulated-by-integrin-%C3%AE-v%C3%AE-3-in-mycobacterium-tuberculosis-infection
#18
Sara Brilha, Riccardo Wysoczanski, Ashley M Whittington, Jon S Friedland, Joanna C Porter
In tuberculosis (TB), the innate inflammatory immune response drives tissue destruction, morbidity, and mortality. Monocytes secrete matrix metalloproteinases (MMPs), which have key roles in local tissue destruction and cavitation. We hypothesized that integrin signaling might regulate monocyte MMP secretion in pulmonary TB during cell adhesion to the extracellular matrix (ECM). Adhesion to type I collagen and fibronectin by Mycobacterium tuberculosis-stimulated monocytes increased MMP-1 gene expression by 2...
August 1, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/28634242/type-ii-secretion-substrates-of-legionella-pneumophila-translocate-out-of-the-pathogen-occupied-vacuole-via-a-semipermeable-membrane
#19
Hilary K Truchan, Harry D Christman, Richard C White, Nakisha S Rutledge, Nicholas P Cianciotto
Legionella pneumophila replicates in macrophages in a host-derived phagosome, termed the Legionella-containing vacuole (LCV). While the translocation of type IV secretion (T4S) effectors into the macrophage cytosol is well established, the location of type II secretion (T2S) substrates in the infected host cell is unknown. Here, we show that the T2S substrate ProA, a metalloprotease, translocates into the cytosol of human macrophages, where it associates with the LCV membrane (LCVM). Translocation is detected as early as 10 h postinoculation (p...
June 20, 2017: MBio
https://www.readbyqxmd.com/read/28633807/differential-induction-of-atf3-and-ho-1-in-myeloid-cells-and-keratinocytes-via-dimethylfumarate-or-cyclosporine-a
#20
Stefanie Müller, Nikola Smatlik, Marc Burian, Kamran Ghoreschi, Martin Röcken, Amir S Yazdi
BACKGROUND: Chronic inflammatory skin diseases are characterized by controlled proliferation of keratinocytes. Here, activating transcription factor 3 (ATF3) might play a fundamental role. In these inflammatory diseases, proliferation is controlled and only rarely leads to cancer development which can be supported by an inflammatory microenvironment. ATF3 is a dual function protein as it suppresses pro-inflammatory IL-6 and IL-8, but also acts as a pro-oncogenic factor by the suppression of p53...
June 12, 2017: Journal of Dermatological Science
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