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Pore forming toxins

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https://www.readbyqxmd.com/read/28930630/assessing-the-structure-and-stability-of-transmembrane-oligomeric-intermediates-of-an-%C3%AE-helical-toxin
#1
Rajat Desikan, Prabal K K Maiti, K Ganapathy Ayappa
Protein membrane interactions play an important role in our understanding of diverse phenomena ranging from membrane assisted protein aggregation to oligomerization and folding. Pore forming toxins (PFTs) form the primary vehicle for infection by several strains of bacteria. These proteins expressed in a water soluble form (monomers) bind to the target membrane (protomer) to form a transmembrane pore complex through a process of oligomerization. Based on the structure of the transmembrane domains, PFTs are broadly classified into β or α toxins...
September 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28927993/voltage-gated-sodium-channel-%C3%AE-subunits-the-power-outside-the-pore-in-brain-development-and-disease
#2
REVIEW
Jacob M Hull, Lori L Isom
Voltage gated sodium channels (VGSCs) were first identified in terms of their role in the upstroke of the action potential. The underlying proteins were later identified as saxitoxin and scorpion toxin receptors consisting of α and β subunits. We now know that VGSCs are heterotrimeric complexes consisting of a single pore forming α subunit joined by two β subunits; a noncovalently linked β1 or β3 and a covalently linked β2 or β4 subunit. VGSC α subunits contain all the machinery necessary for channel cell surface expression, ion conduction, voltage sensing, gating, and inactivation, in one central, polytopic, transmembrane protein...
September 16, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28911869/degradation-of-nuclear-ubc9-induced-by-listeriolysin-o-is-dependent-on-k-efflux
#3
Jiexin Li, Wendy Wai-Ling Lam, Tsz-Wah Lai, Shannon Wing-Ngor Au
Listeriolysin O (LLO) is a pore-forming toxin produced by L. monocytogenes, and is belonged to a protein family of cholesterol-dependent cytolysins (CDCs). Previous studies have demonstrated that LLO triggers Ubc9 degradation and disrupts host SUMOylation to facilitate bacterial infection. However, the underlying mechanism of Ubc9 degradation is unclear. Here we show that LLO-induced down-regulation of Ubc9 is independent of Ubc9-SUMO interaction, however, it may involve phosphorylation signaling. Additionally, LLO exerts its effects primarily on nuclear Ubc9 and this process is mediated by K(+) efflux...
September 11, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28901209/the-distinct-properties-of-natural-and-gm-cry-insecticidal-proteins
#4
Jonathan R Latham, Madeleine Love, Angelika Hilbeck
The Cry toxins are a family of crystal-forming proteins produced by the bacterium Bacillus thuringiensis. Their mode of action is thought to be to create pores that disrupt the gut epithelial membranes of juvenile insects. These pores allow pathogen entry into the hemocoel, thereby killing the insect. Genes encoding a spectrum of Cry toxins, including Cry mutants, Cry chimaeras and other Cry derivatives, are used commercially to enhance insect resistance in genetically modified (GM) crops. In most countries of the world, such GM crops are regulated and must be assessed for human and environmental safety...
September 13, 2017: Biotechnology & Genetic Engineering Reviews
https://www.readbyqxmd.com/read/28892012/bordetella-adenylate-cyclase-hemolysin-toxins
#5
REVIEW
Nicole Guiso
Adenylate cyclase-hemolysin toxin is secreted and produced by three classical species of the genus Bordetella: Bordetella pertussis, B. parapertussis and B. bronchiseptica. This toxin has several properties such as: (i) adenylate cyclase activity, enhanced after interaction with the eukaryotic protein, calmodulin; (ii) a pore-forming activity; (iii) an invasive activity. It plays an important role in the pathogenesis of these Bordetella species responsible for whooping cough in humans or persistent respiratory infections in mammals, by modulating host immune responses...
September 11, 2017: Toxins
https://www.readbyqxmd.com/read/28875177/the-potential-therapeutic-agent-mepacrine-protects-caco-2-cells-against-clostridium-perfringens-enterotoxin-action
#6
John C Freedman, Matthew R Hendricks, Bruce A McClane
Clostridium perfringens enterotoxin (CPE) causes the diarrhea associated with a common bacterial food poisoning and many antibiotic-associated diarrhea cases. The severity of some CPE-mediated disease cases warrants the development of potential therapeutics. A previous study showed that the presence of mepacrine inhibited CPE-induced electrophysiology effects in artificial lipid bilayers lacking CPE receptors. However, that study did not assess whether mepacrine inactivates CPE or, instead, inhibits a step in CPE action...
July 2017: MSphere
https://www.readbyqxmd.com/read/28872615/listeriolysin-o-regulates-the-expression-of-optineurin-an-autophagy-adaptor-that-inhibits-the-growth-of-listeria-monocytogenes
#7
Madhu Puri, Luigi La Pietra, Mobarak Abu Mraheil, Rudolf Lucas, Trinad Chakraborty, Helena Pillich
Autophagy, a well-established defense mechanism, enables the elimination of intracellular pathogens including Listeria monocytogenes. Host cell recognition results in ubiquitination of L. monocytogenes and interaction with autophagy adaptors p62/SQSTM1 and NDP52, which target bacteria to autophagosomes by binding to microtubule-associated protein 1 light chain 3 (LC3). Although studies have indicated that L. monocytogenes induces autophagy, the significance of this process in the infectious cycle and the mechanisms involved remain poorly understood...
September 5, 2017: Toxins
https://www.readbyqxmd.com/read/28865796/ph-regulates-pore-formation-of-a-protease-activated-vip3aa-from-bacillus-thuringiensis
#8
Thittaya Kunthic, Hirokazu Watanabe, Ryuji Kawano, Yoshikazu Tanaka, Boonhiang Promdonkoy, Min Yao, Panadda Boonserm
Vip3Aa insecticidal protein is produced from Bacillus thuringiensis and exerts a broad spectrum of toxicity against lepidopteran insect species. Although Vip3Aa has been effectively used as part of integrated pest management strategies, the mechanism of the toxin remains unclear. Here, we investigated the effect of pH in a range from 5.0 to 10.0 on the pore-forming activity of the trypsin activated Vip3Aa (actVip3Aa) by in vitro pore-forming assays. Based on calcein release assay, actVip3Aa could permeabilize the artificial neutral liposomes under all the pH tested, except pH10...
September 1, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28861073/epithelial-cell-damage-activates-bactericidal-permeability-increasing-protein-bpi-expression-in-intestinal-epithelium
#9
Arjun Balakrishnan, Dipshikha Chakravortty
As the first line of defense against invading pathogen, intestinal epithelium produces various antimicrobial proteins (AMP) that help in clearance of pathogen. Bactericidal/permeability-increasing protein (BPI) is a 55 kDa AMP that is expressed in intestinal epithelium. Dysregulation of BPI in intestinal epithelium is associated with various inflammatory diseases like Crohn's Disease, Ulcerative colitis, and Infectious enteritis's. In this paper, we report a direct correlation between intestinal damage and BPI expression...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28853034/biophysical-and-biochemical-strategies-to-understand-membrane-binding-and-pore-formation-by-sticholysins-pore-forming-proteins-from-a-sea-anemone
#10
REVIEW
Carlos Alvarez, Uris Ros, Aisel Valle, Lohans Pedrera, Carmen Soto, Yadira P Hervis, Sheila Cabezas, Pedro A Valiente, Fabiola Pazos, Maria E Lanio
Actinoporins constitute a unique class of pore-forming toxins found in sea anemones that are able to bind and oligomerize in membranes, leading to cell swelling, impairment of ionic gradients and, eventually, to cell death. In this review we summarize the knowledge generated from the combination of biochemical and biophysical approaches to the study of sticholysins I and II (Sts, StI/II), two actinoporins largely characterized by the Center of Protein Studies at the University of Havana during the last 20 years...
August 29, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28832671/pseudomonas-aeruginosa-exla-and-serratia-marcescens-shla-trigger-cadherin-cleavage-by-promoting-calcium-influx-and-adam10-activation
#11
Emeline Reboud, Stéphanie Bouillot, Sabine Patot, Benoît Béganton, Ina Attrée, Philippe Huber
Pore-forming toxins are potent virulence factors secreted by a large array of bacteria. Here, we deciphered the action of ExlA from Pseudomonas aeruginosa and ShlA from Serratia marcescens on host cell-cell junctions. ExlA and ShlA are two members of a unique family of pore-forming toxins secreted by a two-component secretion system. Bacteria secreting either toxin induced an ExlA- or ShlA-dependent rapid cleavage of E-cadherin and VE-cadherin in epithelial and endothelial cells, respectively. Cadherin proteolysis was executed by ADAM10, a host cell transmembrane metalloprotease...
August 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28827366/spontaneous-virulence-loss-in-natural-populations-of-listeria-monocytogenes
#12
Mylène M Maury, Viviane Chenal-Francisque, Hélène Bracq-Dieye, Lei Han, Alexandre Leclercq, Guillaume Vales, Alexandra Moura, Edith Gouin, Mariela Scortti, Olivier Disson, José A Vázquez-Boland, Marc Lecuit
Listeria monocytogenes (Lm) pathogenesis depends on its ability to escape from the phagosome of the host cells via the action of the pore-forming toxin listeriolysin O (LLO). Expression of the LLO-encoding gene (hly) requires the transcriptional activator PrfA, and both hly and prfA genes are essential for Lm virulence. Here we used the hemolytic activity of LLO as a phenotypic marker to screen for spontaneous virulence-attenuating mutations in Lm Sixty (0.1%) non-hemolytic isolates were identified among a collection of 57,820 confirmed Lm strains isolated from a variety of sources...
August 21, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28821431/bacillus-thuringiensis-cyt2aa2-binding-on-lipid-cholesterol-bilayer-depends-on-protein-concentration-and-time
#13
Sudarat Tharad, Alberto Moreno-Cencerrado, Öykü Üzülmez, Boonhiang Promdonkoy, Jose L Toca-Herrera
Bacillus thuringiensis produces cytolytic proteins (Cyt) that show toxicity against dipteran insect larvae acting directly on the cell membrane. Up to now, two different models have been proposed to explain the interaction mechanism of the cytolytic protein Cyt2Aa2 on lipid membranes: pore-forming and detergent-like action. Here we report on the interaction of Cyt2Aa2 with lipid/cholesterol bilayers at early stage (far from equilibrium) as a function of protein concentration. Quartz crystal microbalance with dissipation (QCM-D) measurements showed that the rate of protein adsorption increased with concentration, although the mass of the final protein-lipid was similar after two hours...
October 14, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28802270/intra-molecular-salt-bridge-in-bacillus-thuringiensis-cry4ba-toxin-is-involved-in-the-stability-of-helix-%C3%AE-3-that-is-needed-for-oligomerization-and-insecticidal-activity
#14
Sabino Pacheco, Isabel Gómez, Jorge Sanchez, Blanca-Ines García-Gómez, Mario Soberón, Alejandra Bravo
Bacillus thuringiensis three domain Cry toxins kill insects by forming pores in the apical membrane of larval midgut cells. Oligomerization of the toxin is an important step for pore formation. Domain I helix α-3 participates in toxin oligomerization. Here we identify an intra-molecular salt bridge within helix α-3 of Cry4Ba (D111-K115) that is conserved in many members of the family of the three-domain Cry toxins. Single point mutations such as D111K or K115D resulted in proteins severely affected in toxicity...
August 11, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28798954/acute-effect-of-pore-forming-clostridium-perfringens-%C3%AE%C2%B5-toxin-on-compound-action-potentials-of-optic-nerve-of-mouse
#15
Mercè Cases, Artur Llobet, Beatrice Terni, Inmaculada Gómez de Aranda, Marta Blanch, Briain Doohan, Alexander Revill, Angus M Brown, Juan Blasi, Carles Solsona
ε-Toxin is a pore forming toxin produced by Clostridium perfringens types B and D. It is synthesized as a less active prototoxin form that becomes fully active upon proteolytic activation. The toxin produces highly lethal enterotoxaemia in ruminants, has the ability to cross the blood-brain barrier (BBB) and specifically binds to myelinated fibers. We discovered that the toxin induced a release of ATP from isolated mice optic nerves, which are composed of myelinated fibers that are extended from the central nervous system...
July 2017: ENeuro
https://www.readbyqxmd.com/read/28779836/lipid-nanodiscs-as-a-tool-for-high-resolution-structure-determination-of-membrane-proteins-by-single-particle-cryo-em
#16
Rouslan G Efremov, Christos Gatsogiannis, Stefan Raunser
The "resolution revolution" in electron cryomicroscopy (cryo-EM) profoundly changed structural biology of membrane proteins. Near-atomic structures of medium size to large membrane protein complexes can now be determined without crystallization. This significantly accelerates structure determination and also the visualization of small bound ligands. There is an additional advantage: the structure of membrane proteins can now be studied in their native or nearly native lipid bilayer environment. A popular lipid bilayer mimetic are lipid nanodiscs, which have been thoroughly characterized and successfully utilized in multiple applications...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28770170/high-throughput-microplate-based-assay-to-monitor-plasma-membrane-wounding-and-repair
#17
Sarika Pathak-Sharma, Xiaoli Zhang, Jonathan G T Lam, Noah Weisleder, Stephanie M Seveau
The plasma membrane of mammalian cells is susceptible to disruption by mechanical and biochemical damages that frequently occur within tissues. Therefore, efficient and rapid repair of the plasma membrane is essential for maintaining cellular homeostasis and survival. Excessive damage of the plasma membrane and defects in its repair are associated with pathological conditions such as infections, muscular dystrophy, heart failure, diabetes, and lung and neurodegenerative diseases. The molecular events that remodel the plasma membrane during its repair remain poorly understood...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28769806/a-red-blood-cell-membrane-camouflaged-nanoparticle-counteracts-streptolysin-o-mediated-virulence-phenotypes-of-invasive-group-a-streptococcus
#18
Tamara Escajadillo, Joshua Olson, Brian T Luk, Liangfang Zhang, Victor Nizet
Group A Streptococcus (GAS), an important human-specific Gram-positive bacterial pathogen, is associated with a broad spectrum of disease, ranging from mild superficial infections such as pharyngitis and impetigo, to serious invasive infections including necrotizing fasciitis and streptococcal toxic shock syndrome. The GAS pore-forming streptolysin O (SLO) is a well characterized virulence factor produced by nearly all GAS clinical isolates. High level expression of SLO is epidemiologically linked to intercontinental dissemination of hypervirulent clonotypes and poor clinical outcomes...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28760979/phospholipase-a-activity-of-adenylate-cyclase-toxin-mediates-translocation-of-its-adenylate-cyclase-domain
#19
David González-Bullón, Kepa B Uribe, César Martín, Helena Ostolaza
Adenylate cyclase toxin (ACT or CyaA) plays a crucial role in respiratory tract colonization and virulence of the whooping cough causative bacterium Bordetella pertussis Secreted as soluble protein, it targets myeloid cells expressing the CD11b/CD18 integrin and on delivery of its N-terminal adenylate cyclase catalytic domain (AC domain) into the cytosol, generates uncontrolled toxic levels of cAMP that ablates bactericidal capacities of phagocytes. Our study deciphers the fundamentals of the heretofore poorly understood molecular mechanism by which the ACT enzyme domain directly crosses the host cell membrane...
August 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28751253/molecular-mechanisms-of-the-action-of-sphingomyelin-specific-pore-forming-toxin-lysenin
#20
REVIEW
Neval Yilmaz, Akiko Yamaji-Hasegawa, Françoise Hullin-Matsuda, Toshihide Kobayashi
Lysenin, which is an earthworm toxin, strongly binds to sphingomyelin (SM). Lysenin oligomerizes on SM-rich domains and can induce cell death by forming pores in the membrane. In this review, the assembly of lysenin on SM-containing membranes is discussed mostly on the basis of the information gained by atomic force microscopy (AFM). AFM data show that lysenin assembles into a hexagonal close packed (hcp) structure by rapid reorganization of its oligomers on an SM/cholesterol membrane. In case of a phase-separated membrane of SM, lysenin induces phase mixing as a result of pore formation in SM-rich domains, and consequently its hcp assembly covers the entire membrane...
July 24, 2017: Seminars in Cell & Developmental Biology
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