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Pore forming toxins

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https://www.readbyqxmd.com/read/28733486/%C3%AE-toxin-regulates-local-granulocyte-expansion-from-hematopoietic-stem-and-progenitor-cells-in-staphylococcus-aureus-infected-wounds
#1
Patrick C Falahee, Leif S Anderson, Mack B Reynolds, Mauricio Pirir, Bridget E McLaughlin, Carly A Dillen, Ambrose L Cheung, Lloyd S Miller, Scott I Simon
The immune response to Staphylococcus aureus infection in skin involves the recruitment of polymorphonuclear neutrophils (PMNs) from the bone marrow via the circulation and local granulopoiesis from hematopoietic stem and progenitor cells (HSPCs) that also traffic to infected skin wounds. We focus on regulation of PMN number and function and the role of pore-forming α-toxin (AT), a virulence factor that causes host cell lysis and elicits inflammasome-mediated IL-1β secretion in wounds. Infection with wild-type S...
July 21, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/28720729/inhibition-of-inflammasome-dependent-interleukin-1%C3%AE-production-by-streptococcal-nad-glycohydrolase-evidence-for-extracellular-activity
#2
Dóra Hancz, Elsa Westerlund, Benedicte Bastiat-Sempe, Onkar Sharma, Christine Valfridsson, Lena Meyer, John F Love, Maghnus O'Seaghdha, Michael R Wessels, Jenny J Persson
Group A Streptococcus (GAS) is a common human pathogen and the etiologic agent of a large number of diseases ranging from mild, self-limiting infections to invasive life-threatening conditions. Two prominent virulence factors of this bacterium are the genetically and functionally linked pore-forming toxin streptolysin O (SLO) and its cotoxin NAD(+)-glycohydrolase (NADase). Overexpression of these toxins has been linked to increased bacterial virulence and is correlated with invasive GAS disease. NADase can be translocated into host cells by a SLO-dependent mechanism, and cytosolic NADase has been assigned multiple properties such as protection of intracellularly located GAS bacteria and induction of host cell death through energy depletion...
July 18, 2017: MBio
https://www.readbyqxmd.com/read/28710557/lysionotin-attenuates-staphylococcus-aureus-pathogenicity-by-inhibiting-%C3%AE-toxin-expression
#3
Zihao Teng, Dongxue Shi, Huanyu Liu, Ziying Shen, Yonghong Zha, Wenhua Li, Xuming Deng, Jianfeng Wang
α-Toxin, one of the best known pore-forming proteins produced by Staphylococcus aureus (S. aureus), is a critical virulence factor in multiple infections. The necessity of α-toxin for S. aureus pathogenicity suggests that this toxin is an important target for the development of a potential treatment strategy. In this study, we showed that lysionotin, a natural compound, can inhibit the hemolytic activity of culture supernatants by S. aureus by reducing α-toxin expression. Using real-time PCR analysis, we showed that transcription of hla (the gene encoding α-toxin) and agr (the locus regulating hla) was significantly inhibited by lysionotin...
July 14, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28685236/engineered-cry1ac-cry9aa-hybrid-bacillus-thuringiensis-delta-endotoxin-with-improved-insecticidal-activity-against-helicoverpa-armigera
#4
Jigar V Shah, Rakeshkumar Yadav, Sanjay S Ingle
Recombinant Bt construct was prepared by exchange of pore forming domain I with cry1Ac to cry9Aa gene by overlap extension PCR (OE-PCR) technique. Construction of cry1Ac-cry9Aa was accomplished by six base pair homology at 3' ends of PCR products of domain I of cry1Ac and domain II and III of cry9Aa. The recombinant toxin was also modified by deletion of N-terminal alpha helix-1 of recombinant toxin. Both Cry toxins were expressed in E. coli BL21(DE3) plysS and purified by His-tag purification. Upon insect bioassay analysis against devastating crop pest Helicoverpa armigera, toxicity of recombinant toxin was found around fivefold higher than native Cry1Ac while alpha helix-1 deleted N-terminal modified toxin did not resulted in significant increase in toxicity...
July 6, 2017: Archives of Microbiology
https://www.readbyqxmd.com/read/28676354/cry46ab-from-bacillus-thuringiensis-tk-e6-is-a-new-mosquitocidal-toxin-with-aerolysin-type-architecture
#5
Tohru Hayakawa, Akira Sakakibara, Sho Ueda, Yoshinao Azuma, Toru Ide, So Takebe
Cry46Ab is a Cry toxin derived from Bacillus thuringiensis TK-E6. Cry46Ab is not significantly homologous to other mosquitocidal Cry or Cyt toxins and is classified as an aerolysin-type pore-forming toxin based on structural similarity. In this study, the potency of Cry46Ab was assessed for its potential application to mosquito control. A synthetic Cry46Ab gene, cry46Ab-S1, was designed to produce recombinant Cry46Ab as a glutathione-S-transferase fusion in Escherichia coli. Recombinant Cry46Ab showed apparent toxicity to Culex pipiens larvae, with a 50% lethal dose of 1...
July 1, 2017: Insect Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28657583/epidermal-growth-factor-receptor-signaling-enhances-the-proinflammatory-effects-of-staphylococcus-aureus-gamma-toxin-on-the-mucosa
#6
Aaron N Gillman, Laura M Breshears, Charles K Kistler, Patrick M Finnegan, Victor J Torres, Patrick M Schlievert, Marnie L Peterson
Staphylococcus aureus (S. aureus) produces many different exotoxins including the gamma-toxins, HlgAB and HlgCB. Gamma-toxins form pores in both leukocyte and erythrocyte membranes, resulting in cell lysis. The genes encoding gamma-toxins are present in most strains of S. aureus, and are commonly expressed in clinical isolates recovered from menstrual Toxic Shock Syndrome (mTSS) patients. This study set out to investigate the cytotoxic and proinflammatory effects of gamma-toxins on vaginal epithelial surfaces...
June 28, 2017: Toxins
https://www.readbyqxmd.com/read/28654176/multiple-pseudomonas-species-secrete-exolysin-like-toxins-and-provoke-caspase-1-dependent-macrophage-death
#7
REVIEW
Pauline Basso, Pierre Wallet, Sylvie Elsen, Emmanuelle Soleilhac, Thomas Henry, Eric Faudry, Ina Attrée
Pathogenic bacteria secrete protein toxins that provoke apoptosis or necrosis of eukaryotic cells. Here, we developed a live-imaging method, based on incorporation of a DNA-intercalating dye into membrane-damaged host cells, to study the kinetics of primary bone marrow-derived macrophages (BMDMs) mortality induced by opportunistic pathogen Pseudomonas aeruginosa expressing either Type III Secretion System (T3SS) toxins or the pore-forming toxin, Exolysin (ExlA). We found that ExlA promotes the activation of Caspase-1 and maturation of interleukin-1β...
June 27, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28647534/molecular-cell-biology-of-complement-membrane-attack
#8
REVIEW
B Paul Morgan, Courtney Boyd, Doryen Bubeck
The membrane attack complex (MAC) is the pore-forming toxin of the complement system, a relatively early evolutionary acquisition that confers upon complement the capacity to directly kill pathogens. The MAC is more than just a bactericidal missile, having the capacity when formed on self-cells to initiate a host of cell activation events that can have profound consequences for tissue homeostasis in the face of infection or injury. Although the capacity of complement to directly kill pathogens has been recognised for over a century, and the pore-forming killing mechanism for at least 50 years, there remains considerable uncertainty regarding precisely how MAC mediates its killing and cell activation activities...
June 21, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/28630160/listeriolysin-o-from-bazooka-to-swiss-army-knife
#9
REVIEW
Suzanne E Osborne, John H Brumell
Listeria monocytogenes (Lm) is a Gram-positive facultative intracellular pathogen. Infections in humans can lead to listeriosis, a systemic disease with a high mortality rate. One important mechanism of Lm dissemination involves cell-to-cell spread after bacteria have entered the cytosol of host cells. Listeriolysin O (LLO; encoded by the hly gene) is a virulence factor present in Lm that plays a central role in the cell-to-cell spread process. LLO is a member of the cholesterol-dependent cytolysin (CDC) family of toxins that were initially thought to promote disease largely by inducing cell death and tissue destruction-essentially acting like a 'bazooka'...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28630155/haemolytic-actinoporins-interact-with-carbohydrates-using-their-lipid-binding-module
#10
Koji Tanaka, Jose M M Caaveiro, Koldo Morante, Kouhei Tsumoto
Pore-forming toxins (PFTs) are proteins endowed with metamorphic properties that enable them to stably fold in water solutions as well as in cellular membranes. PFTs produce lytic pores on the plasma membranes of target cells conducive to lesions, playing key roles in the defensive and offensive molecular systems of living organisms. Actinoporins are a family of potent haemolytic toxins produced by sea anemones vigorously studied as a paradigm of α-helical PFTs, in the context of lipid-protein interactions, and in connection with nanopore technologies...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28630151/assembly-mechanism-of-the-%C3%AE-pore-forming-toxin-cytolysin-a-from-escherichia-coli
#11
REVIEW
Daniel Roderer, Rudi Glockshuber
The cytolytic toxin cytolysin A (ClyA) from Escherichia coli is probably one of the best-characterized examples of bacterial, α-pore-forming toxins (α-PFTs). Like other PFTs, ClyA exists in a soluble, monomeric form that assembles to an annular, homo-oligomeric pore complex upon contact with detergent or target membranes. Comparison of the three-dimensional structures of the 34 kDa monomer and the protomer in the context of the dodecameric pore complex revealed that ClyA undergoes one of the largest conformational transitions described for proteins so far, in which 55% of the residues change their position and 16% of the residues adopt a different secondary structure in the protomer...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28630149/molecular-mechanism-of-pore-formation-by-aerolysin-like-proteins
#12
REVIEW
Marjetka Podobnik, Matic Kisovec, Gregor Anderluh
Aerolysin-like pore-forming proteins are an important family of proteins able to efficiently damage membranes of target cells by forming transmembrane pores. They are characterized by a unique domain organization and mechanism of action that involves extensive conformational rearrangements. Although structures of soluble forms of many different members of this family are well understood, the structures of pores and their mechanism of assembly have been described only recently. The pores are characterized by well-defined β-barrels, which are devoid of any vestibular regions commonly found in other protein pores...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28623231/cry6aa1-a-bacillus-thuringiensis-nematocidal-and-insecticidal-toxin-forms-pores-in-planar-lipid-bilayers-at-extremely-low-concentrations-and-without-the-need-of-proteolytic-processing
#13
Eva Fortea, Vincent Lemieux, Léna Potvin, Vimbai Chikwana, Samantha Griffin, Thimothy Hey, David McCaskill, Kenneth Narva, Sek Yee Tan, Xiaoping Xu, Vincent Vachon, Jean-Louis Schwartz
Cry6Aa1 is a Bacillus thuringiensis (Bt) toxin active against nematodes and corn rootworm insects. Its 3-D molecular structure, which has been recently elucidated, is unique among those known for other Bt toxins. Typical three-domain Bt toxins permeabilise receptor-free planar lipid bilayers (PLBs) by forming pores at doses in the 1-50 μg/ml range. Solubilisation and proteolytic activation are necessary steps for PLB permeabilisation. In contrast to other Bt toxins, Cry6Aa1 formed pores in receptor-free bilayers at doses as low as 200 pg/ml in a wide range of pH (5...
June 16, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28607368/nmr-structure-of-the-bacillus-cereus-hemolysin-ii-c-terminal-domain-reveals-a-novel-fold
#14
Anne R Kaplan, Katherine Kaus, Swastik De, Rich Olson, Andrei T Alexandrescu
In addition to multiple virulence factors, Bacillus cereus a pathogen that causes food poisoning and life-threatening wound infections, secretes the pore-forming toxin hemolysin II (HlyII). The HlyII toxin has a unique 94 amino acid C-terminal domain (HlyIIC). HlyIIC exhibits splitting of NMR resonances due to cis/trans isomerization of a single proline near the C-terminus. To overcome heterogeneity, we solved the structure of P405M-HlyIIC, a mutant that exclusively stabilizes the trans state. The NMR structure of HlyIIC reveals a novel fold, consisting of two subdomains αA-β1-β2 and β3-β4-αB-β5, that come together in a barrel-like structure...
June 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28567044/curcumin-promotes-the-clearance-of-listeria-monocytogenes-both-in-vitro-and-in-vivo-by-reducing-listeriolysin-o-oligomers
#15
Xuan Zhou, Bing Zhang, Yumei Cui, Shuiye Chen, Zihao Teng, Gejin Lu, Jianfeng Wang, Xuming Deng
The pore-forming toxin listeriolysin O (LLO), an essential virulence factor that is secreted by Listeria monocytogenes (L. monocytogenes), is responsible for bacterial breaching at the phagosomal membranes and subsequent release into the cytoplasm; it cannot be recognized by the host immune system. The vital role that LLO plays in bacterial pathogenicity and evading host immune clearance makes this virulence a promising target for addressing L. monocytogenes infection. In this study, we hypothesized that curcumin, a polyphenol derived from turmeric that could effectively inhibit LLO pore-forming activity, might be useful in the prevention or treatment of L...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28561794/antibiotic-resistance-and-virulence-phenotypes-of-recent-bacterial-strains-isolated-from-urinary-tract-infections-in-elderly-patients-with-prostatic-disease
#16
Cristina Delcaru, Paulina Podgoreanu, Ionela Alexandru, Nela Popescu, Luminiţa Măruţescu, Coralia Bleotu, George Dan Mogoşanu, Mariana Carmen Chifiriuc, Marinela Gluck, Veronica Lazăr
Acute bacterial prostatitis is one of the frequent complications of urinary tract infection (UTI). From the approximately 10% of men having prostatitis, 7% experience a bacterial prostatitis. The purpose of this study was to investigate the prevalence of uropathogens associated with UTIs in older patients with benign prostatic hyperplasia and to assess their susceptibility to commonly prescribed antibiotics as well as the relationships between microbial virulence and resistance features. Uropathogenic Escherichia coli was found to be the most frequent bacterial strain isolated from patients with benign prostatic hyperplasia, followed by Enterococcus spp...
May 31, 2017: Pathogens
https://www.readbyqxmd.com/read/28550293/stochastic-sensing-of-angiotensin-ii-with-lysenin-channels
#17
Nisha Shrestha, Sheenah L Bryant, Christopher Thomas, Devon Richtsmeier, Xinzhu Pu, Juliette Tinker, Daniel Fologea
The ability of pore-forming proteins to interact with various analytes has found vast applicability in single molecule sensing and characterization. In spite of their abundance in organisms from all kingdoms of life, only a few pore-forming proteins have been successfully reconstituted in artificial membrane systems for sensing purposes. Lysenin, a pore-forming toxin extracted from the earthworm E. fetida, inserts large conductance nanopores in lipid membranes containing sphingomyelin. Here we show that single lysenin channels may function as stochastic nanosensors by allowing the short cationic peptide angiotensin II to be electrophoretically driven through the conducting pathway...
May 26, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28546115/both-polarity-and-aromatic-ring-in-the-side-chain-of-tryptophan-246-are-involved-in-binding-activity-of-vibrio-vulnificus-hemolysin-to-target-cells
#18
Takashige Kashimoto, Tomoe Akita, Takehiro Kado, Kohei Yamazaki, Shunji Ueno
Vibrio vulnificus secretes a hemolysin/cytolysin (VVH) that induces cytolysis against a variety of mammalian cells by forming pores on the cellular membrane. VVH is known to bind to the cellular membrane as a monomer, and then convert to a pore-forming oligomer. However, the structural basis for binding of this toxin to target cells remains unknown. We show here that the polarity and indole ring on the side chain of Trp 246 (W246) of VVH, which sits on a bottom loop, participates in binding to cellular membrane...
May 22, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28546029/gardnerella-vaginalis-bacteremia-associated-with-severe-acute-encephalopathy-in-a-young-female-patient
#19
Jacques Tankovic, Albertas Timinskas, Migle Janulaitiene, Milda Zilnyte, Jean-Luc Baudel, Eric Maury, Aurelija Zvirbliene, Milda Pleckaityte
Gardnerella vaginalis is a facultative anaerobic bacterium that inhabits the genitourinary tract of both healthy women and those with bacterial vaginosis. We report a case of G. vaginalis bacteremia associated with severe toxic encephalopathy in a young woman. Anaerobic blood cultures yielded pure growth of small gram-variable rods later identified as G. vaginalis by both rapid biochemical tests and 16S rRNA gene sequencing. The patient recovered after treatment with amoxicillin-clavulanate according to the in vitro susceptibility testing...
May 22, 2017: Anaerobe
https://www.readbyqxmd.com/read/28545305/clostridium-difficile-toxins-a-and-b-receptors-pores-and-translocation-into-cells
#20
Kathleen E Orrell, Zhifen Zhang, Seiji N Sugiman-Marangos, Roman A Melnyk
The most potent toxins secreted by pathogenic bacteria contain enzymatic moieties that must reach the cytosol of target cells to exert their full toxicity. Toxins such as anthrax, diphtheria, and botulinum toxin all use three well-defined functional domains to intoxicate cells: a receptor-binding moiety that triggers endocytosis into acidified vesicles by binding to a specific host-cell receptor, a translocation domain that forms pores across the endosomal membrane in response to acidic pH, and an enzyme that translocates through these pores to catalytically inactivate an essential host cytosolic substrate...
May 26, 2017: Critical Reviews in Biochemistry and Molecular Biology
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