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Pore forming toxins

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https://www.readbyqxmd.com/read/28196960/repair-of-a-bacterial-small-%C3%AE-barrel-toxin-pore-depends-on-channel-width
#1
Gisela von Hoven, Amable J Rivas, Claudia Neukirch, Martina Meyenburg, Qianqian Qin, Sapun Parekh, Nadja Hellmann, Matthias Husmann
Membrane repair emerges as an innate defense protecting target cells against bacterial pore-forming toxins. Here, we report the first paradigm of Ca(2+)-dependent repair following attack by a small β-pore-forming toxin, namely, plasmid-encoded phobalysin of Photobacterium damselae subsp. damselae In striking contrast, Vibrio cholerae cytolysin, the closest ortholog of phobalysin, subverted repair. Mutational analysis uncovered a role of channel width in toxicity and repair. Thus, the replacement of serine at phobalysin´s presumed channel narrow point with the bulkier tryptophan, the corresponding residue in Vibrio cholerae cytolysin (W318), modulated Ca(2+) influx, lysosomal exocytosis, and membrane repair...
February 14, 2017: MBio
https://www.readbyqxmd.com/read/28193196/rapid-eradication-of-colon-carcinoma-by-clostridium-perfringens-enterotoxin-suicidal-gene-therapy
#2
Jessica Pahle, Lutz Menzel, Nicole Niesler, Dennis Kobelt, Jutta Aumann, Maria Rivera, Wolfgang Walther
BACKGROUND: Bacterial toxins have evolved to an effective therapeutic option for cancer therapy. The Clostridium perfringens enterotoxin (CPE) is a pore-forming toxin with selective cytotoxicity. The transmembrane tight junction proteins claudin-3 and -4 are known high affinity CPE receptors. Their expression is highly upregulated in human cancers, including breast, ovarian and colon carcinoma. CPE binding to claudins triggers membrane pore complex formation, which leads to rapid cell death...
February 13, 2017: BMC Cancer
https://www.readbyqxmd.com/read/28186501/intrinsic-repair-protects-cells-from-pore-forming-toxins-by-microvesicle-shedding
#3
Matthew Romero, Michelle Keyel, Guilan Shi, Pushpak Bhattacharjee, Robyn Roth, John E Heuser, Peter A Keyel
Pore-forming toxins (PFTs) are used by both the immune system and by pathogens to disrupt cell membranes. Cells attempt to repair this disruption in various ways, but the exact mechanism(s) that cells use are not fully understood, nor agreed upon. Current models for membrane repair include (1) patch formation (e.g., fusion of internal vesicles with plasma membrane defects), (2) endocytosis of the pores, and (3) shedding of the pores by blebbing from the cell membrane. In this study, we sought to determine the specific mechanism(s) that cells use to resist three different cholesterol-dependent PFTs: Streptolysin O, Perfringolysin O, and Intermedilysin...
February 10, 2017: Cell Death and Differentiation
https://www.readbyqxmd.com/read/28176876/engineering-a-ph-responsive-pore-forming-protein
#4
Matic Kisovec, Saša Rezelj, Primož Knap, Miša Mojca Cajnko, Simon Caserman, Ajda Flašker, Nada Žnidaršič, Matej Repič, Janez Mavri, Yi Ruan, Simon Scheuring, Marjetka Podobnik, Gregor Anderluh
Listeriolysin O (LLO) is a cytolysin capable of forming pores in cholesterol-rich lipid membranes of host cells. It is conveniently suited for engineering a pH-governed responsiveness, due to a pH sensor identified in its structure that was shown before to affect its stability. Here we introduced a new level of control of its hemolytic activity by making a variant with hemolytic activity that was pH-dependent. Based on detailed structural analysis coupled with molecular dynamics and mutational analysis, we found that the bulky side chain of Tyr406 allosterically affects the pH sensor...
February 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28173991/damage-of-eukaryotic-cells-by-the-pore-forming-toxin-sticholysin-ii-consequences-of-the-potassium-efflux
#5
Sheila Cabezas, Sylvia Ho, Uris Ros, María E Lanio, Carlos Alvarez, F Gisou van der Goot
Pore-forming toxins (PFTs) form holes in membranes causing one of the most catastrophic damages to a target cell. Target organisms have evolved a regulated response against PFTs damage including cell membrane repair. This ability of cells strongly depends on the toxin concentration and the properties of the pores. It has been hypothesized that there is an inverse correlation between the size of the pores and the time required to repair the membrane, which has been for long a non-intuitive concept and far to be completely understood...
February 4, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28137589/participation-of-perforin-in-mediating-dopaminergic-neuron-loss-in-mptp-induced-parkinson-s-disease-in-mice
#6
Su-Ping Peng, Ye Zhang, Sjef Copray, Melitta Schachner, Yan-Qin Shen
Both resident innate and peripheral immune aberrations have been demonstrated to influence Parkinson's disease (PD) progression. However, it is still enigmatic how and which immune components are lethal to the dopaminergic neuron in PD. We now show that levels of perforin, a pore-forming protein expressed in cytotoxic immune cells, was significantly increased in the serum of wild-type mice 4 weeks after injection of MPTP, a toxin used to induce PD-like symptoms. We demonstrate that perforin-deficiency attenuated the acute striatal dopamine reduction by 33%, ablated microglia activation 3 days post MPTP-injection; and retarded dopaminergic neuron death 4 weeks post MPTP-injection...
March 11, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28128281/targeted-delivery-of-an-adp-ribosylating-bacterial-toxin-into-cancer-cells
#7
N-I Zahaf, A E Lang, L Kaiser, C D Fichter, S Lassmann, A McCluskey, A Augspach, K Aktories, G Schmidt
The actin cytoskeleton is an attractive target for bacterial toxins. The ADP-ribosyltransferase TccC3 from the insect bacterial pathogen Photorhabdus luminescence modifies actin to force its aggregation. We intended to transport the catalytic part of this toxin preferentially into cancer cells using a toxin transporter (Protective antigen, PA) which was redirected to Epidermal Growth Factor Receptors (EGFR) or to human EGF receptors 2 (HER2), which are overexpressed in several cancer cells. Protective antigen of anthrax toxin forms a pore through which the two catalytic parts (lethal factor and edema factor) or other proteins can be transported into mammalian cells...
January 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28125817/participation-of-necroptosis-in-the-host-response-to-acute-bacterial-pneumonia
#8
Danielle Ahn, Alice Prince
Common pulmonary pathogens, such as Streptococcus pneumoniae and Staphylococcus aureus, as well as the host-adapted pathogens responsible for health care-associated pneumonias, such as the carbapenem-resistant Klebsiella pneumoniae and Serratia marcecsens, are able to activate cell death through the RIPK1/RIPK3/MLKL cascade that causes necroptosis. Necroptosis can influence the pathogenesis of pneumonia through several mechanisms. Activation of this pathway can result in the loss of specific types of immune cells, especially macrophages, and, in so doing, contribute to host pathology through the loss of their critical immunoregulatory functions...
January 27, 2017: Journal of Innate Immunity
https://www.readbyqxmd.com/read/28119472/pseudomonas-aeruginosa-pore-forming-exolysin-and-type-iv-pili-cooperate-to-induce-host-cell-lysis
#9
Pauline Basso, Michel Ragno, Sylvie Elsen, Emeline Reboud, Guillaume Golovkine, Stephanie Bouillot, Philippe Huber, Stephen Lory, Eric Faudry, Ina Attrée
: Clinical strains of Pseudomonas aeruginosa lacking the type III secretion system genes employ a toxin, exolysin (ExlA), for host cell membrane disruption. Here, we demonstrated that ExlA export requires a predicted outer membrane protein, ExlB, showing that ExlA and ExlB define a new active two-partner secretion (TPS) system of P. aeruginosa In addition to the TPS signals, ExlA harbors several distinct domains, which include one hemagglutinin domain, five arginine-glycine-aspartic acid (RGD) motifs, and a C-terminal region lacking any identifiable sequence motifs...
January 24, 2017: MBio
https://www.readbyqxmd.com/read/28115202/secondary-structure-preferences-of-the-anthrax-toxin-protective-antigen-translocase
#10
Debasis Das, Bryan A Krantz
In order for many proteins to move across hydrophobic membrane bilayers, they must be unfolded and translocated by a membrane-embedded channel. These translocase channels interact with the substrate proteins they translocate via hydrophobic pore loops and cleft structures, called clamps. The molecular basis for how clamps facilitate unfolding and translocation is poorly understood. Anthrax toxin is comprised of three proteins, a translocase channel forming subunit, called protective antigen (PA), and two substrate proteins, called lethal factor (LF) and edema factor...
January 20, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28106142/identification-of-lukpq-a-novel-equid-adapted-leukocidin-of-staphylococcus-aureus
#11
Gerrit Koop, Manouk Vrieling, Daniel M L Storisteanu, Laurence S C Lok, Tom Monie, Glenn van Wigcheren, Claire Raisen, Xiaoliang Ba, Nicholas Gleadall, Nazreen Hadjirin, Arjen J Timmerman, Jaap A Wagenaar, Heleen M Klunder, J Ross Fitzgerald, Ruth Zadoks, Gavin K Paterson, Carmen Torres, Andrew S Waller, Anette Loeffler, Igor Loncaric, Armando E Hoet, Karin Bergström, Luisa De Martino, Constança Pomba, Hermínia de Lencastre, Karim Ben Slama, Haythem Gharsa, Emily J Richardson, Edwin R Chilvers, Carla de Haas, Kok van Kessel, Jos A G van Strijp, Ewan M Harrison, Mark A Holmes
Bicomponent pore-forming leukocidins are a family of potent toxins secreted by Staphylococcus aureus, which target white blood cells preferentially and consist of an S- and an F-component. The S-component recognizes a receptor on the host cell, enabling high-affinity binding to the cell surface, after which the toxins form a pore that penetrates the cell lipid bilayer. Until now, six different leukocidins have been described, some of which are host and cell specific. Here, we identify and characterise a novel S...
January 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28088448/fast-formation-of-low-defect-density-tethered-bilayers-by-fusion-of-multilamellar-vesicles
#12
Tadas Ragaliauskas, Mindaugas Mickevicius, Bozena Rakovska, Tadas Penkauskas, David J Vanderah, Frank Heinrich, Gintaras Valincius
A facile and reproducible preparation of surface-supported lipid bilayers is essential for fundamental membrane research and biotechnological applications. We demonstrate that multilamellar vesicles fuse to molecular-anchor-grafted surfaces yielding low-defect-density, tethered bilayer membranes. Continuous bilayers are formed within 10min, while the electrically insulating bilayers with <0.1μm(-2) defect density can be accomplished within 60min. Surface plasmon resonance spectroscopy indicates that an amount of lipid material transferred from vesicles to a surface is inversely proportional to the density of an anchor, while the total amount of lipid that includes tethered and transferred lipid remains constant within 5% standard error...
January 12, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28081446/host-to-host-transmission-of-streptococcus-pneumoniae-is-driven-by-its-inflammatory-toxin-pneumolysin
#13
M Ammar Zafar, Yang Wang, Shigeto Hamaguchi, Jeffrey N Weiser
Host-to-host transmission is a critical step for infection. Here we studied transmission of the opportunistic pathogen Streptococcus pneumoniae in an infant mouse model. Transmission from nasally colonized pups required high levels of bacterial shedding in nasal secretions and was temporally correlated with, and dependent upon, the acute inflammatory response. Pneumolysin, a pore-forming cytotoxin and major virulence determinant, was both necessary and sufficient to promote inflammation, which increased shedding and allowed for intralitter transmission...
January 11, 2017: Cell Host & Microbe
https://www.readbyqxmd.com/read/28074026/promyelocytic-leukemia-protein-pml-controls-listeria-monocytogenes-infection
#14
David Ribet, Valérie Lallemand-Breitenbach, Omar Ferhi, Marie-Anne Nahori, Hugo Varet, Hugues de Thé, Pascale Cossart
: The promyelocytic leukemia protein (PML) is the main organizer of stress-responsive subnuclear structures called PML nuclear bodies. These structures recruit multiple interactors and modulate their abundance or their posttranslational modifications, notably by the SUMO ubiquitin-like modifiers. The involvement of PML in antiviral responses is well established. In contrast, the role of PML in bacterial infection remains poorly characterized. Here, we show that PML restricts infection by the pathogenic bacterium Listeria monocytogenes but not by Salmonella enterica serovar Typhimurium...
January 10, 2017: MBio
https://www.readbyqxmd.com/read/28062388/netf-producing-clostridium-perfringens-clonality-and-plasmid-pathogenicity-loci-analysis
#15
Iman Mehdizadeh Gohari, Andrew M Kropinski, Scott J Weese, Ashley E Whitehead, Valeria R Parreira, Patrick Boerlin, John F Prescott
Clostridium perfringens is an important cause of foal necrotizing enteritis and canine acute hemorrhagic diarrhea. A major virulence determinant of the strains associated with these diseases appears to be a beta-sheet pore-forming toxin, NetF, encoded within a pathogenicity locus (NetF locus) on a large tcp-conjugative plasmid. Strains producing NetF also produce the putative toxin NetE, encoded within the same pathogenicity locus, as well as CPE enterotoxin and CPB2 on a second plasmid, and sometimes the putative toxin NetG within a pathogenicity locus (NetG locus) on another separate large conjugative plasmid...
January 3, 2017: Infection, Genetics and Evolution
https://www.readbyqxmd.com/read/28060924/the-effector-domain-region-of-the-vibrio-vulnificus-martx-toxin-confers-biphasic-epithelial-barrier-disruption-and-is-essential-for-systemic-spread-from-the-intestine
#16
Hannah E Gavin, Nike T Beubier, Karla J F Satchell
Vibrio vulnificus causes highly lethal bacterial infections in which the Multifunctional Autoprocessing Repeats-in-Toxins (MARTX) toxin product of the rtxA1 gene is a key virulence factor. MARTX toxins are secreted proteins up to 5208 amino acids in size. Conserved MARTX N- and C-terminal repeat regions work in concert to form pores in eukaryotic cell membranes, through which the toxin's central region of modular effector domains is translocated. Upon inositol hexakisphosphate-induced activation of the of the MARTX cysteine protease domain (CPD) in the eukaryotic cytosol, effector domains are released from the holotoxin by autoproteolytic activity...
January 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28048967/the-pore-forming-capacity-of-sticholysin-i-in-dipalmitoyl-phosphatidyl-vesicles-is-tuned-by-osmotic-stress
#17
M Ahumada, C Calderon, E Lissi, C Alvarez, M E Lanio, F Pazos
The osmotic condition modulates the properties of liposomes, particularly those related to their stability and response to external agents such as membrane-active proteins or peptides. In a previous work, we have demonstrated that an osmotic shock can increase, per se, water influx/efflux and the exit of the fluorophore calcein entrapped in the aqueous pool of dipalmitoylphosphatidylcholine (DPPC) and DPPC:sphingomyelin (SM) large unilamellar vesicles (LUVs), suggesting a loss of integrity of the liposome bilayer...
December 31, 2016: Chemistry and Physics of Lipids
https://www.readbyqxmd.com/read/28039206/endoplasmic-reticulum-chaperone-gp96-controls-actomyosin-dynamics-and-protects-against-pore-forming-toxins
#18
Francisco Sarmento Mesquita, Cláudia Brito, Maria J Mazon Moya, Jorge Campos Pinheiro, Serge Mostowy, Didier Cabanes, Sandra Sousa
During infection, plasma membrane (PM) blebs protect host cells against bacterial pore-forming toxins (PFTs), but were also proposed to promote pathogen dissemination. However, the details and impact of blebbing regulation during infection remained unclear. Here, we identify the endoplasmic reticulum chaperone Gp96 as a novel regulator of PFT-induced blebbing. Gp96 interacts with non-muscle myosin heavy chain IIA (NMHCIIA) and controls its activity and remodelling, which is required for appropriate coordination of bleb formation and retraction...
February 2017: EMBO Reports
https://www.readbyqxmd.com/read/28003061/azadinium-poporum-from-the-argentine-continental-shelf-southwestern-atlantic-produces-azaspiracid-2-and-azaspiracid-2-phosphate
#19
Urban Tillmann, C Marcela Borel, Facundo Barrera, Rubén Lara, Bernd Krock, Gastón O Almandoz, Matthias Witt, Nicole Trefault
The marine dinophycean genus Azadinium has been identified as the primary source of azaspiracids (AZA), a group of lipophilic phycotoxins known to accumulate in shellfish. Blooms of Azadinium in the southern Atlantic off Argentina have been described from the 1990s, but due to a lack of cultures, the diversity of South-Atlantic Azadinium has not yet been fully explored and their toxin production potential is completely unknown. During a spring 2010 research cruise covering the El Rincón (ER) estuarine system (North Patagonian coast, Argentina, Southwestern Atlantic) a search was conducted for the presence of Azadinium...
January 2016: Harmful Algae
https://www.readbyqxmd.com/read/27995777/a-return-to-the-pore-dissecting-bacillus-thuringiensis-toxin-mode-of-action-via-voltage-clamp-experiments
#20
David G Heckel
Pore-forming toxins from Bacillus thuringiensis are increasingly used in crop protection, but evolution of resistance in crop pests threatens their continued deployment. A study by Tanaka et al. shows how voltage clamp experiments that quantify pore formation can be used to dissect toxin mode of action, thereby revealing unexpected complexities that could be exploited to counter resistance.
December 2016: FEBS Journal
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