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Pore forming toxins

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https://www.readbyqxmd.com/read/28533492/anti-tumor-activity-of-anthrax-toxin-variants-that-form-a-functional-translocation-pore-by-intermolecular-complementation
#1
Shihui Liu, Qian Ma, Rasem Fattah, Thomas H Bugge, Stephen H Leppla
Anthrax lethal toxin is a typical A-B type protein toxin secreted by Bacillus anthracis. Lethal factor (LF) is the catalytic A-subunit, a metalloprotease having MEKs as targets. LF relies on the cell-binding B-subunit, protective antigen (PA), to gain entry into the cytosol of target cells. PA binds to cell surface toxin receptors and is activated by furin protease to form an LF-binding-competent oligomer-PA pre-pore, which converts to a functional protein-conductive pore in the acidic endocytic vesicles, allowing translocation of LF into the cytosol...
May 9, 2017: Oncotarget
https://www.readbyqxmd.com/read/28526816/delineation-of-b-cell-epitopes-of-salmonella-enterica-serovar-typhi-hemolysin-e-potential-antibody-therapeutic-target
#2
Chai Fung Chin, Jing Yi Lai, Yee Siew Choong, Amy Amilda Anthony, Asma Ismail, Theam Soon Lim
Hemolysin E (HlyE) is an immunogenic novel pore-forming toxin involved in the pathogenesis of typhoid fever. Thus, mapping of B-cell epitopes of Salmonella enterica serovar Typhi (S. Typhi) is critical to identify key immunogenic regions of HlyE. A random 20-mer peptide library was used for biopanning with enriched anti-HlyE polyclonal antibodies from typhoid patient sera. Bioinformatic tools were used to refine, analyze and map the enriched peptide sequences against the protein to identify the epitopes. The analysis identified both linear and conformational epitopes on the HlyE protein...
May 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28522850/pseudomonas-aeruginosa-exolysin-promotes-bacterial-growth-in-lungs-alveolar-damage-and-bacterial-dissemination
#3
Stéphanie Bouillot, Patrick Munro, Benoit Gallet, Emeline Reboud, François Cretin, Guillaume Golovkine, Guy Schoehn, Ina Attrée, Emmanuel Lemichez, Philippe Huber
Exolysin (ExlA) is a recently-identified pore-forming toxin secreted by a subset of Pseudomonas aeruginosa strains identified worldwide and devoid of Type III secretion system (T3SS), a major virulence factor. Here, we characterized at the ultrastructural level the lesions caused by an ExlA-secreting strain, CLJ1, in mouse infected lungs. CLJ1 induced necrotic lesions in pneumocytes and endothelial cells, resulting in alveolo-vascular barrier breakdown. Ectopic expression of ExlA in an exlA-negative strain induced similar tissue injuries...
May 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28516064/a-novel-role-of-listeria-monocytogenes-membrane-vesicles-in-inhibition-of-autophagy-and-cell-death
#4
Svitlana Vdovikova, Morten Luhr, Paula Szalai, Lars Nygård Skalman, Monika K Francis, Richard Lundmark, Nikolai Engedal, Jörgen Johansson, Sun N Wai
Bacterial membrane vesicle (MV) production has been mainly studied in Gram-negative species. In this study, we show that Listeria monocytogenes, a Gram-positive pathogen that causes the food-borne illness listeriosis, produces MVs both in vitro and in vivo. We found that a major virulence factor, the pore-forming hemolysin listeriolysin O (LLO), is tightly associated with the MVs, where it resides in an oxidized, inactive state. Previous studies have shown that LLO may induce cell death and autophagy. To monitor possible effects of LLO and MVs on autophagy, we performed assays for LC3 lipidation and LDH sequestration as well as analysis by confocal microscopy of HEK293 cells expressing GFP-LC3...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28505109/the-vip3ag4-insecticidal-protoxin-from-bacillus-thuringiensis-adopts-a-tetrameric-configuration-that-is-maintained-on-proteolysis
#5
Leopoldo Palma, David J Scott, Gemma Harris, Salah-Ud Din, Thomas L Williams, Oliver J Roberts, Mark T Young, Primitivo Caballero, Colin Berry
The Vip3 proteins produced during vegetative growth by strains of the bacterium Bacillus thuringiensis show insecticidal activity against lepidopteran insects with a mechanism of action that may involve pore formation and apoptosis. These proteins are promising supplements to our arsenal of insecticidal proteins, but the molecular details of their activity are not understood. As a first step in the structural characterisation of these proteins, we have analysed their secondary structure and resolved the surface topology of a tetrameric complex of the Vip3Ag4 protein by transmission electron microscopy...
May 14, 2017: Toxins
https://www.readbyqxmd.com/read/28488084/loop-diuretics-diminish-hemolysis-induced-by-%C3%AE-hemolysin-from-escherichia-coli
#6
Carl Martin Söderström, Steen K Fagerberg, Mette B Brogaard, Jens Leipziger, Marianne Skals, Helle A Praetorius
Uropathogenic Escherichia coli often produce the virulence factor α-hemolysin (HlyA), and the more severe the infection, the likelier it is to isolate HlyA-producing E. coli from patients. HlyA forms pores upon receptor-independent insertion of the toxin into biological membranes and it has been substantiated that HlyA-induced hemolysis is amplified by toxin-induced ATP release and activation of P2X receptors. Thus, hemolysis inflicted by HlyA is a protracted process involving signal transduction. It consists of early, marked cell shrinkage followed by swelling and eventually lysis...
May 9, 2017: Journal of Membrane Biology
https://www.readbyqxmd.com/read/28484467/immunogenic-domains-and-secondary-structure-of-escherichia-coli-recombinant-secreted-protein-escherichia-coli-secreted-protein-b
#7
Bruna Alves Caetano, Letícia Barboza Rocha, Eneas Carvalho, Roxane Maria Fontes Piazza, Daniela Luz
Several pathogenic bacteria are able to induce the attaching and effacing (A/E) lesion. The A/E lesion is caused by effector proteins, such as Escherichia coli-secreted protein B (EspB), responsible together with Escherichia coli-secreted protein D for forming a pore structure on the host cell, which allows the translocation of effector proteins. Different variants of this protein can be found in E. coli strains, and during natural infection or when this protein is injected, this leads to variant-specific production of antibodies, which may not be able to recognize other variants of this bacterial protein...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28481307/histopathological-effects-of-bt-and-tcda-insecticidal-proteins-on-the-midgut-epithelium-of-western-corn-rootworm-larvae-diabrotica-virgifera-virgifera
#8
Andrew J Bowling, Heather E Pence, Huarong Li, Sek Yee Tan, Steven L Evans, Kenneth E Narva
Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is a major corn pest in the United States, causing annual losses of over $1 billion. One approach to protect against crop loss by this insect is the use of transgenic corn hybrids expressing one or more crystal (Cry) proteins derived from Bacillus thuringiensis. Cry34Ab1 and Cry35Ab1 together comprise a binary insecticidal toxin with specific activity against WCR. These proteins have been developed as insect resistance traits in commercialized corn hybrids resistant to WCR feeding damage...
May 8, 2017: Toxins
https://www.readbyqxmd.com/read/28455832/structure-and-function-of-the-two-component-cytotoxins-of-staphylococcus-aureus-learnings-for-designing-novel-therapeutics
#9
Adriana Badarau, Nikolina Trstenjak, Eszter Nagy
Staphylococcus aureus can produce up to five different bi-component cytotoxins: two gamma-hemolysins HlgAB and HlgCB, and leukocidins SF-PV (Panton Valentine leukocidin), ED (LukED) and GH (LukGH, also called LukAB). Their major function in S. aureus pathogenesis is to evade innate immunity by attacking phagocytic cells and to support bacterial growth by lysing red blood cells. The five cytotoxins display different levels of amino acid sequence conservation (30-82%), but all form a remarkably similar beta-barrel type pore structure (greatly resembling the mono-component toxin alpha-hemolysin) that inserts into the target cell membrane leading to necrotic cell death...
April 29, 2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28451868/juglone-alleviates-pneumolysin-induced-human-alveolar-epithelial-cell-injury-via-inhibiting-the-hemolytic-activity-of-pneumolysin
#10
Meng Song, Gejin Lu, Meng Li, Xuming Deng, Jianfeng Wang
Streptococcus pneumoniae (the pneumococcus) is an opportunistic pathogen responsible for several human diseases, including acute otitis media, pneumonia, sepsis and bacterial meningitis, and possesses numerous virulence factors associated with pneumococcal infection and pathogenesis. With the capacity to form pores in cholesterol-rich membranes, pneumolysin (PLY) is a key virulence factor of S. pneumoniae and causes severe tissue damage during pneumococcal infection. Juglone (JG), a natural 1,4-naphthoquinone widely found in the roots, leaves, woods and fruits of Juglandaceae walnut trees, inhibits PLY-induced hemolysis via inhibition of the oligomerization of PLY and exhibits minimal anti-S...
April 27, 2017: Antonie Van Leeuwenhoek
https://www.readbyqxmd.com/read/28445785/staphylococcus-aureus-pore-forming-toxins-the-interface-of-pathogen-and-host-complexity
#11
REVIEW
E Sachiko Seilie, Juliane Bubeck Wardenburg
Staphylococcus aureus is a prominent human pathogen capable of infecting a variety of host species and tissue sites. This versatility stems from the pathogen's ability to secrete diverse host-damaging virulence factors. Among these factors, the S. aureus pore-forming toxins (PFTs), α-toxin and the bicomponent leukocidins, have garnered much attention for their ability to lyse cells at low concentrations and modulate disease severity. Although many of these toxins were discovered nearly a century ago, their host cell specificity has only been elucidated over the past five to six years, starting with the discovery of the eukaryotic receptor for α-toxin and rapidly followed by identification of the leukocidin receptors...
April 23, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/28420883/leukocidins-staphylococcal-bi-component-pore-forming-toxins-find-their-receptors
#12
REVIEW
András N Spaan, Jos A G van Strijp, Victor J Torres
Staphylococcus aureus is a major bacterial pathogen that causes disease worldwide. The emergence of strains that are resistant to commonly used antibiotics and the failure of vaccine development have resulted in a renewed interest in the pathophysiology of this bacterium. Staphylococcal leukocidins are a family of bi-component pore-forming toxins that are important virulence factors. During the past five years, cellular receptors have been identified for all of the bi-component leukocidins. The identification of the leukocidin receptors explains the cellular tropism and species specificity that is exhibited by these toxins, which has important biological consequences...
April 19, 2017: Nature Reviews. Microbiology
https://www.readbyqxmd.com/read/28396322/camp-elevating-capacity-of-the-adenylate-cyclase-toxin-hemolysin-is-sufficient-for-lung-infection-but-not-for-full-virulence-of-bordetella-pertussis
#13
Karolina Skopova, Barbora Tomalova, Ivan Kanchev, Pavel Rossmann, Martina Svedova, Irena Adkins, Ilona Bibova, Jakub Tomala, Jiri Masin, Nicole Guiso, Radim Osicka, Radislav Sedlacek, Marek Kovar, Peter Sebo
The adenylate cyclase toxin-hemolysin (CyaA, ACT or AC-Hly) of Bordetella pertussis targets phagocytic cells expressing the complement receptor 3 (CR3, Mac-1, αMβ2 integrin or CD11b/CD18). CyaA delivers into cells an N-terminal adenylyl cyclase (AC) enzyme domain that is activated by cytosolic calmodulin and catalyzes unregulated conversion of cellular ATP into cAMP, a key second messenger subverting bactericidal activities of phagocytes. In parallel, the hemolysin (Hly) moiety of CyaA forms cation-selective hemolytic pores that permeabilize target cell membranes...
April 10, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28396016/differential-binding-and-activity-of-the-pore-forming-toxin-sticholysin-ii-in-model-membranes-containing-diverse-ceramide-derived-lipids
#14
Carmen Soto, Anaixis Del Valle, Pedro A Valiente, Uris Ros, María E Lanio, Ana M Hernández, Carlos Alvarez
Sticholysin II is a pore-forming toxin produced by the sea anemone Stichodactyla helianthus that belongs to the actinoporin protein family. The high affinity of actinoporins for sphingomyelin (SM)-containing membranes has been well documented. However, the molecular determinants that define this affinity have not been fully clarified. Here, we have examined the binding and permeabilizing activity of StII to different single and mixed lipidic systems by combining lipid monolayers, liposomes, and permeabilizing assays...
April 7, 2017: Biochimie
https://www.readbyqxmd.com/read/28387756/pore-forming-toxin-mediated-ion-dysregulation-leads-to-death-receptor-independent-necroptosis-of-lung-epithelial-cells-during-bacterial-pneumonia
#15
Norberto González-Juarbe, Kelley Margaret Bradley, Anukul Taranath Shenoy, Ryan Paul Gilley, Luis Felipe Reyes, Cecilia Anahí Hinojosa, Marcos Ignacio Restrepo, Peter Herman Dube, Molly Ann Bergman, Carlos Javier Orihuela
We report that pore-forming toxins (PFTs) induce respiratory epithelial cell necroptosis independently of death receptor signaling during bacterial pneumonia. Instead, necroptosis was activated as a result of ion dysregulation arising from membrane permeabilization. PFT-induced necroptosis required RIP1, RIP3 and MLKL, and could be induced in the absence or inhibition of TNFR1, TNFR2 and TLR4 signaling. We detected activated MLKL in the lungs from mice and nonhuman primates experiencing Serratia marcescens and Streptococcus pneumoniae pneumonia, respectively...
May 2017: Cell Death and Differentiation
https://www.readbyqxmd.com/read/28382496/molecular-evolutionary-constraints-that-determine-the-avirulence-state-of-clostridium-botulinum-c2-toxin
#16
A Prisilla, R Prathiviraj, P Chellapandi
Clostridium botulinum (group-III) is an anaerobic bacterium producing C2 toxin along with botulinum neurotoxins. C2 toxin is belonged to binary toxin A family in bacterial ADP-ribosylation superfamily. A structural and functional diversity of binary toxin A family was inferred from different evolutionary constraints to determine the avirulence state of C2 toxin. Evolutionary genetic analyses revealed evidence of C2 toxin cluster evolution through horizontal gene transfer from the phage or plasmid origins, site-specific insertion by gene divergence, and homologous recombination event...
April 5, 2017: Journal of Molecular Evolution
https://www.readbyqxmd.com/read/28379176/ostreolysin-a-pleurotolysin-b-and-equinatoxins-structure-function-and-pathophysiological-effects-of-these-pore-forming-proteins
#17
REVIEW
Robert Frangež, Dušan Šuput, Jordi Molgó, Evelyne Benoit
Acidic ostreolysin A/pleurotolysin B (OlyA/PlyB, formerly known as ostreolysin (Oly), and basic 20 kDa equinatoxins (EqTs) are cytolytic proteins isolated from the edible mushroom Pleurotus ostreatus and the sea anemone Actinia equina, respectively. Both toxins, although from different sources, share many similar biological activities: (i) colloid-osmotic shock by forming pores in cellular and artificial membranes enriched in cholesterol and sphingomyelin; (ii) increased vascular endothelial wall permeability in vivo and perivascular oedema; (iii) dose-dependent contraction of coronary vessels; (iv) haemolysis with pronounced hyperkalaemia in vivo; (v) bradycardia, myocardial ischemia and ventricular extrasystoles accompanied by progressive fall of arterial blood pressure and respiratory arrest in rodents...
April 5, 2017: Toxins
https://www.readbyqxmd.com/read/28373868/morin-attenuates-streptococcus-suis-pathogenicity-in-mice-by-neutralizing-suilysin-activity
#18
Gen Li, Gejin Lu, Zhimin Qi, Hongen Li, Lin Wang, Yanhui Wang, Bowen Liu, Xiaodi Niu, Xuming Deng, Jianfeng Wang
Streptococcus suis, a Gram-positive pathogen, is widely recognized as an important agent of swine infection, and it is also known to cause a variety of zoonoses, such as meningitis, polyarthritis and pneumonia. Suilysin (SLY), an extracellular pore-forming toxin that belongs to the cholesterol-dependent cytolysin family, is an essential virulence factor of S. suis capsular type 2 (SS2). Here, we found that morin hydrate (morin), a natural flavonoid that lacks anti-SS2 activity, inhibits the hemolytic activity of SLY, protects J774 cells from SS2-induced injury and protects mice from SS2 infection...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28344124/comparative-genomics-of-transport-proteins-in-probiotic-and-pathogenic-escherichia-coli-and-salmonella-enterica-strains
#19
Jimmy Do, Hassan Zafar, Milton H Saier
Escherichia coli is a genetically diverse species that can be pathogenic, probiotic, commensal, or a harmless laboratory strain. Pathogenic strains of E. coli cause urinary tract infections, diarrhea, hemorrhagic colitis, and pyelonephritis, while the two known probiotic E. coli strains combat inflammatory bowel disease and play a role in immunomodulation. Salmonella enterica, a close relative of E. coli, includes two important pathogenic serovars, Typhi and Typhimurium, causing typhoid fever and enterocolitis in humans, respectively, with the latter strain also causing a lethal typhoid fever-like disease in mice...
March 24, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28341807/the-human-cancer-cell-active-toxin-cry41aa-from-bacillus-thuringiensis-acts-like-its-insecticidal-counterparts
#20
Vidisha Krishnan, Barbara Domanska, Alicia Elhigazi, Fatai Afolabi, Michelle J West, Neil Crickmore
Understanding how certain protein toxins from the normally insecticidal bacterium Bacillus thuringiensis target human cell lines has implications for both the risk assessment of products containing these toxins and potentially for cancer therapy. This understanding requires knowledge of whether the human cell active toxins work by the same mechanism as their insecticidal counterparts or by alternative ones. The B. thuringiensis Cry41Aa (also known as Parasporin3) toxin is structurally related to the toxins synthesized by commercially produced transgenic insect-resistant plants, with the notable exception of an additional C-terminal beta-trefoil ricin domain...
March 24, 2017: Biochemical Journal
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