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Pore forming toxins

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https://www.readbyqxmd.com/read/29330180/genomic-and-phenotypic-characterization-of-type-strains-and-dairy-associated-isolates-in-the-bacillus-cereus-group-indicates-considerable-intra-clade-variability-in-toxin-production-and-cytotoxicity
#1
Rachel A Miller, Jiahui Jian, Sarah M Beno, Martin Wiedmann, Jasna Kovac
While some species in the B. cereus group are well-characterized human pathogens (e.g., B. anthracis and B. cereus s.s.), the pathogenicity of other species (e.g., B. pseudomycoides) either has not been characterized or is presently not well understood. To provide an updated characterization of the pathogenic potential of species in the B. cereus group, we classified a set of 52 isolates, including 8 type strains and 44 environmental isolates from dairy-associated sources, into 7 phylogenetic clades and characterized them for (i) the presence of toxin genes, (ii) phenotypic characteristics used for identification, and (iii) cytotoxicity to human epithelial cells...
January 12, 2018: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29317705/pneumolysin-induced-mitochondrial-dysfunction-leads-to-release-of-mitochondrial-dna
#2
Andreas Nerlich, Maren Mieth, Eleftheria Letsiou, Diana Fatykhova, Katja Zscheppang, Aki Imai-Matsushima, Thomas F Meyer, Lisa Paasch, Timothy J Mitchell, Mario Tönnies, Torsten T Bauer, Paul Schneider, Jens Neudecker, Jens C Rückert, Stephan Eggeling, Maria Schimek, Martin Witzenrath, Norbert Suttorp, Stefan Hippenstiel, Andreas C Hocke
Streptococcus pneumoniae (S.pn.) is the most common bacterial pathogen causing community acquired pneumonia. The pore-forming toxin pneumolysin (PLY) is the major virulence factor of S.pn. and supposed to affect alveolar epithelial cells thereby activating the immune system by liberation of danger-associated molecular patterns (DAMP). To test this hypothesis, we established a novel live-cell imaging based assay to analyse mitochondrial function and associated release of mitochondrial DNA (mtDNA) as DAMP in real-time...
January 9, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29315018/molecular-characterization-and-expression-of-pft-an-fhb-resistance-gene-at-the-fhb1-qtl-in-wheat
#3
Yi He, Xu Zhang, Yu Zhang, Dawood Ahmad, Lei Wu, Peng Jiang, Hongxiang Ma Ma
Fusarium head blight (FHB) is a destructive fungal disease in wheat worldwide. Efforts have been carried out to combat this disease, and the PFT (pore-forming toxin-like) gene at the quantitative trait locus (QTL) Fhb1 was isolated and found to confer resistance to FHB in Sumai 3. In this study, we characterized PFT in 348 wheat accessions. Four haplotypes of PFT were identified. The wild haplotype of PFT had higher resistance than other haplotypes and explained 13.8% of phenotypic variation in FHB resistance by association analysis...
January 9, 2018: Phytopathology
https://www.readbyqxmd.com/read/29311091/neutralizing-%C3%AE-toxin-accelerates-healing-of-staphylococcus-aureus-infected-wounds-in-normal-and-diabetic-mice
#4
Roger V Ortines, Haiyun Liu, Lily I Cheng, Taylor S Cohen, Heather Lawlor, Abhishek Gami, Yu Wang, Carly A Dillen, Nathan K Archer, Robert J Miller, Alyssa G Ashbaugh, Bret L Pinsker, Mark C Marchitto, Christine Tkaczyk, C Kendall Stover, Bret R Sellman, Lloyd S Miller
Staphylococcus aureus wound infections delay healing and result in invasive complications such as osteomyelitis, especially in the setting of diabetic foot ulcers. In preclinical animal models of S. aureus skin infection, antibody neutralization of α-toxin (AT), a S. aureus secreted pore-forming cytolytic toxin, reduces disease severity by inhibiting skin necrosis and restoring effective host immune responses. However, whether therapeutic neutralization of α-toxin is effective against S. aureus-infected wounds is unclear...
January 8, 2018: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/29295977/staphylococcus-aureus-produces-pain-through-pore-forming-toxins-and-neuronal-trpv1-that-is-silenced-by-qx-314
#5
Kimbria J Blake, Pankaj Baral, Tiphaine Voisin, Ashira Lubkin, Felipe Almeida Pinho-Ribeiro, Kelsey L Adams, David P Roberson, Yuxin C Ma, Michael Otto, Clifford J Woolf, Victor J Torres, Isaac M Chiu
The hallmark of many bacterial infections is pain. The underlying mechanisms of pain during live pathogen invasion are not well understood. Here, we elucidate key molecular mechanisms of pain produced during live methicillin-resistant Staphylococcus aureus (MRSA) infection. We show that spontaneous pain is dependent on the virulence determinant agr and bacterial pore-forming toxins (PFTs). The cation channel, TRPV1, mediated heat hyperalgesia as a distinct pain modality. Three classes of PFTs-alpha-hemolysin (Hla), phenol-soluble modulins (PSMs), and the leukocidin HlgAB-directly induced neuronal firing and produced spontaneous pain...
January 2, 2018: Nature Communications
https://www.readbyqxmd.com/read/29278369/cellular-entry-of-binary-and-pore-forming-bacterial-toxins
#6
EDITORIAL
Alexey S Ladokhin
No abstract text is available yet for this article.
December 26, 2017: Toxins
https://www.readbyqxmd.com/read/29273510/epigallocatechin-gallate-can-attenuate-human-alveolar-epithelial-cell-injury-induced-by-alpha-haemolysin
#7
Yonglin Zhou, Chengzhen Chen, Juan Pan, Xuming Deng, Jianfeng Wang
Staphylococcus aureus (S. aureus) is a common cause of hospital-acquired infection and has become an epidemic globally. Alpha-haemolysin (α-haemolysin), a pore-forming toxin, is one of the most important virulence factors secreted by most S. aureus strains. α-haemolysin monomers form a 232.4-kDa membrane-inserted heptamer by self-assembling to cause host cell lysis and death. Consequently, α-haemolysin plays a significant role in the pathogenesis of S. aureus, and it could be the target for the treatment of staphylococcal infection...
December 19, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/29259728/control-of-cytoskeletal-dynamics-during-cellular-responses-to-pore-forming-toxins
#8
Francisco Sarmento Mesquita, Cláudia Brito, Didier Cabanes, Sandra Sousa
Following damage by pore forming toxins (PFTs) host cells engage repair processes and display profound cytoskeletal remodeling and concomitant plasma membrane (PM) blebbing. We have recently demonstrated that host cells utilize similar mechanisms to control cytoskeletal dynamics in response to PFTs and during cell migration. This involves assembly of cortical actomyosin bundles, reorganisation of the endoplasmic reticulum (ER) network, and the interaction between the ER chaperone Gp96 and the molecular motor Non-muscle Myosin Heavy Chain IIA (NMHCIIA)...
2017: Communicative & Integrative Biology
https://www.readbyqxmd.com/read/29246155/zno-nanoparticles-modulate-the-ionic-transport-and-voltage-regulation-of-lysenin-nanochannels
#9
Sheenah L Bryant, Josh E Eixenberger, Steven Rossland, Holly Apsley, Connor Hoffmann, Nisha Shrestha, Michael McHugh, Alex Punnoose, Daniel Fologea
BACKGROUND: The insufficient understanding of unintended biological impacts from nanomaterials (NMs) represents a serious impediment to their use for scientific, technological, and medical applications. While previous studies have focused on understanding nanotoxicity effects mostly resulting from cellular internalization, recent work indicates that NMs may interfere with transmembrane transport mechanisms, hence enabling contributions to nanotoxicity by affecting key biological activities dependent on transmembrane transport...
December 16, 2017: Journal of Nanobiotechnology
https://www.readbyqxmd.com/read/29202038/a-novel-biomimetic-nanosponge-protects-the-retina-from-the-enterococcus-faecalis-cytolysin
#10
Austin L LaGrow, Phillip S Coburn, Frederick C Miller, Craig Land, Salai Madhumathi Parkunan, Brian T Luk, Weiwei Gao, Liangfang Zhang, Michelle C Callegan
Intraocular infections are a potentially blinding complication of common ocular surgeries and traumatic eye injuries. Bacterial toxins synthesized in the eye can damage intraocular tissue, often resulting in poor visual outcomes. Enteroccocus faecalis causes blinding infections and is responsible for 8 to 17% of postoperative endophthalmitis cases. These infections are increasingly difficult to treat due to the emergence of multidrug-resistant strains. Virulent E. faecalis isolates secrete a pore-forming bicomponent cytolysin that contributes to retinal tissue damage during endophthalmitis...
November 2017: MSphere
https://www.readbyqxmd.com/read/29187576/host-cell-perforation-by-listeriolysin-o-llo-activates-a-ca2-dependent-cpkc-rac1-arp2-3-signaling-pathway-that-promotes-l-monocytogenes-internalization-independently-of-membrane-resealing
#11
Jonathan Lam, Stephen Vadia, Sarika Pathak-Sharma, Eric McLaughlin, Xiaoli Zhang, Joel Swanson, Stephanie Seveau
Host cell invasion is an indispensable step for a successful infection by intracellular pathogens. Recent studies identified pathogen-induced host cell plasma membrane perforation as a novel mechanism used by diverse pathogens (Trypanosoma cruzi, Listeria monocytogenes, and adenovirus) to promote their internalization into target cells. It was concluded that T. cruzi and adenovirus damage the host cell plasma membrane to hijack the endocytic-dependent membrane resealing machinery, thereby invading the host cell...
November 29, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/29169570/morphology-and-phylogeny-of-prorocentrum-caipirignum-sp-nov-dinophyceae-a-new-tropical-toxic-benthic-dinoflagellate
#12
Silvia M Nascimento, M Cristina Q Mendes, Mariângela Menezes, Francisco Rodríguez, Catharina Alves-de-Souza, Suema Branco, Pilar Riobó, José Franco, José Marcos C Nunes, Mariusz Huk, Steven Morris, Santiago Fraga
A new species of toxic benthic dinoflagellate is described based on laboratory cultures isolated from two locations from Brazil, Rio de Janeiro and Bahia. The morphology was studied with SEM and LM. Cells are elliptical in right thecal view and flat. They are 37-44μm long and 29-36μm wide. The right thecal plate has a V shaped indentation where six platelets can be identified. The thecal surface of both thecal plates is smooth and has round or kidney shaped and uniformly distributed pores except in the central area of the cell, and a line of marginal pores...
December 2017: Harmful Algae
https://www.readbyqxmd.com/read/29168745/interaction-of-cholesterol-with-perfringolysin-o-what-have-we-learned-from-functional-analysis
#13
Sergey N Savinov, Alejandro P Heuck
Cholesterol-dependent cytolysins (CDCs) constitute a family of pore-forming toxins secreted by Gram-positive bacteria. These toxins form transmembrane pores by inserting a large β-barrel into cholesterol-containing membranes. Cholesterol is absolutely required for pore-formation. For most CDCs, binding to cholesterol triggers conformational changes that lead to oligomerization and end in pore-formation. Perfringolysin O (PFO), secreted by Clostridium perfringens, is the prototype for the CDCs. The molecular mechanisms by which cholesterol regulates the cytolytic activity of the CDCs are not fully understood...
November 23, 2017: Toxins
https://www.readbyqxmd.com/read/29150505/cry64ba-and-cry64ca-two-etx-mtx2-bacillus-thuringiensis-insecticidal-proteins-against-hemipteran-pests
#14
Yonglei Liu, Yinglong Wang, Changlong Shu, Kejian Lin, Fuping Song, Alejandra Bravo, Mario Soberón, Jie Zhang
Genetically modified crops that express insecticidal Bacillus thuringiensis (Bt) proteins have become a primary approach for control of lepidopteran (moth) and coleopteran (beetle) pests that feed by chewing the plants. However, the sap-sucking insects (Hemiptera) are not particularly susceptible to Bt toxins. In this study, we describe two Cry toxins (Cry64Ba and Cry64Ca) from a Bt 1012 strain showed toxicity against two important rice hemipteran pests, Laodelphax striatellus and Sogatella furcifera Both of these two proteins contain an ETX/MTX2 domain, and share common sequence features with the β-pore forming toxins...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29148811/continuous-pore-spanning-lipid-bilayers-on-silicon-oxide-coated-porous-substrates
#15
Nelli Teske, Jeremias Sibold, Johannes Schumacher, Nikolas K Teiwes, Martin Gleisner, Ingo P Mey, Claudia Steinem
A number of techniques has been developed and analyzed in recent years to generate pore-spanning membranes (PSMs). While quite a number of methods rely on nanoporous substrates, only a few use micrometer-sized pores to be able to individually resolve suspending membranes by means of fluorescence microscopy. To be able to produce PSMs on pores that are micrometer in size, an orthogonal functionalization strategy resulting in a hydrophilic surface is highly desirable. Here, we report on a method to prepare PSMs based on the evaporation of a thin layer of silicon monoxide on top of the porous substrate...
November 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29138096/one-single-salt-bridge-explains-the-different-cytolytic-activities-shown-by-actinoporins-sticholysin-i-and-ii-from-the-venom-of-stichodactyla-helianthus
#16
Esperanza Rivera-de-Torre, Juan Palacios-Ortega, Sara García-Linares, José G Gavilanes, Álvaro Martínez-Del-Pozo
Sticholysins I and II (StnI and StnII), α-pore forming toxins from the sea anemone Stichodactyla helianthus, are water-soluble toxic proteins which upon interaction with lipid membranes of specific composition bind to the bilayer, extend and insert their N-terminal α-helix, and become oligomeric integral membrane structures. The result is a pore that leads to cell death by osmotic shock. StnI and StnII show 93% of sequence identity, but also different membrane pore-forming activities. The hydrophobicity profile along the first 18 residues revealed differences which were canceled by substituting StnI amino acids 2 and 9...
November 11, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/29120408/exolysin-shapes-the-virulence-of-pseudomonas-aeruginosa-clonal-outliers
#17
REVIEW
Emeline Reboud, Pauline Basso, Antoine P Maillard, Philippe Huber, Ina Attrée
Bacterial toxins are important weapons of toxicogenic pathogens. Depending on their origin, structure and targets, they show diverse mechanisms of action and effects on eukaryotic cells. Exolysin is a secreted 170 kDa pore-forming toxin employed by clonal outliers of Pseudomonas aeruginosa providing to some strains a hyper-virulent behaviour. This group of strains lacks the major virulence factor used by classical strains, the Type III secretion system. Here, we review the structural features of the toxin, the mechanism of its secretion and the effects of the pore formation on eukaryotic cells...
November 9, 2017: Toxins
https://www.readbyqxmd.com/read/29117526/lysenin-toxin-membrane-insertion-is-ph-dependent-but-independent-of-neighboring-lysenins
#18
Ignacio L B Munguira, Hirohide Takahashi, Ignacio Casuso, Simon Scheuring
Pore-forming toxins form a family of proteins that act as virulence factors of pathogenic bacteria, but similar proteins are found in all kingdoms of life, including the vertebrate immune system. They are secreted as soluble monomers that oligomerize on target membranes in the so-called prepore state; after activation, they insert into the membrane and adopt the pore state. Lysenin is a pore-forming toxin from the earthworm Eisenida foetida, of which both the soluble and membrane-inserted structures are solved...
November 7, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/29114985/coordinated-delivery-and-function-of-bacterial-martx-toxin-effectors
#19
REVIEW
Patrick J Woida, Karla J F Satchell
Bacteria often coordinate virulence factors to fine-tune the host response during infection. These coordinated events can include toxins counteracting or amplifying effects of another toxin or though regulating the stability of virulence factors to remove their function once it is no longer needed. Multifunctional autoprocessing repeats-in toxin (MARTX) toxins are effector delivery toxins that form a pore into the plasma membrane of a eukaryotic cell to deliver multiple effector proteins into the cytosol of the target cell...
November 8, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/29111771/staphylococcus-aureus-alpha-toxin-induces-actin-filament-remodeling-in-human-airway-epithelial-model-cells
#20
Sabine Ziesemer, Ina Eiffler, Alfrun Schönberg, Christian Müller, Falko Hochgräfe, Achim G Beule, Jan-Peter Hildebrandt
Exposure of cultured human airway epithelial model cells (16HBE14o-, S9) to Staphylococcus aureus alpha-toxin (hemolysin A, Hla) induces changes in cell morphology and cell layer integrity which are due to the inability of the cells to maintain stable cell-cell or focal contacts and to properly organize their actin cytoskeleton. The aim of this study was to identify Hla-activated signaling pathways involved in regulating the phosphorylation level of the actin depolymerizing factor cofilin. We used recombinant wild-type Hla (rHla) as well as a variant of Hla (rHla-H35L) that is unable to form functional transmembrane pores to treat immortalized human airway epithelial cells (16HBE14o-, S9) as well as freshly isolated human nasal tissue...
November 7, 2017: American Journal of Respiratory Cell and Molecular Biology
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