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https://www.readbyqxmd.com/read/28821431/bacillus-thuringiensis-cyt2aa2-binding-on-lipid-cholesterol-bilayer-depends-on-protein-concentration-and-time
#1
Sudarat Tharad, Alberto Moreno-Cencerrado, Öykü Üzülmez, Boonhiang Promdonkoy, Jose L Toca-Herrera
Bacillus thuringiensis is a bacterium known for its bioinsecticide properties. Besides Cry toxins, B. thuringiensis also produces cytolytic proteins (Cyt) that show toxicity against dipteran insect larvae. Two different models have been proposed in order 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 as a function of protein concentration...
August 15, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28796264/lytic-cell-death-induced-by-melittin-bypasses-pyroptosis-but-induces-nlrp3-inflammasome-activation-and-il-1%C3%AE-release
#2
Fátima Martín-Sánchez, Juan José Martínez-García, María Muñoz-García, Miriam Martínez-Villanueva, José A Noguera-Velasco, David Andreu, Luís Rivas, Pablo Pelegrín
The nucleotide-binding domain and leucine-rich repeat-containing receptor with a pyrin domain 3 (NLRP3) inflammasome is a sensor for different types of infections and alterations of homeostatic parameters, including abnormally high levels of the extracellular nucleotide ATP or crystallization of different metabolites. All NLRP3 activators trigger a similar intracellular pathway, where a decrease in intracellular K(+) concentration and permeabilization of plasma membrane are key steps. Cationic amphipathic antimicrobial peptides and peptide toxins permeabilize the plasma membrane...
August 10, 2017: Cell Death & Disease
https://www.readbyqxmd.com/read/28779836/lipid-nanodiscs-as-a-tool-for-high-resolution-structure-determination-of-membrane-proteins-by-single-particle-cryo-em
#3
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/28777960/in-situ-surface-transfer-process-of-cry1ac-protein-on-sio2%C3%AF-the-effect-of-biosurfactants-for-desorption
#4
Shuzhou Miao, Xingzhong Yuan, Yunshan Liang, Hou Wang, Lijian Leng, Zhibin Wu, Longbo Jiang, Yifu Li, Dan Mo, Guangming Zeng
Genetically modified Bacillus thuringiensis (Bt) crops, which have been widely used in agricultural transgenic plants, express insecticidal Cry proteins and release the toxin into soils. Taking into consideration the environmental risk of Cry proteins, biosurfactant-rhamnolipids were applied to desorb Cry proteins from soil environment, which has not been elucidated before. Quartz crystal microbalance with dissipation (QCM-D) was used in this article to investigate the adsorption and desorption behaviors of Cry1Ac on SiO2 surface (model soil)...
July 25, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28777088/production-biophysical-characterization-and-crystallization-of-pseudomonas-putida-graa-and-its-complexes-with-grat-and-the-grata-operator
#5
Ariel Talavera, Hedvig Tamman, Andres Ainelo, San Hadǽi, Abel Garcia-Pino, Rita Hõrak, Albert Konijnenberg, Remy Loris
The graTA operon from Pseudomonas putida encodes a toxin-antitoxin module with an unusually moderate toxin. Here, the production, SAXS analysis and crystallization of the antitoxin GraA, the GraTA complex and the complex of GraA with a 33 bp operator fragment are reported. GraA forms a homodimer in solution and crystallizes in space group P21, with unit-cell parameters a = 66.9, b = 48.9, c = 62.7 Å, β = 92.6°. The crystals are likely to contain two GraA dimers in the asymmetric unit and diffract to 1...
August 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/28751219/structural-studies-with-bnsp-7-reveal-an-atypical-oligomeric-conformation-compared-to-phospholipases-a2-like-toxins
#6
Lino Fernando G de Lima, Rafael J Borges, Maria Alejandra Viviescas, Carlos A H Fernandes, Marcos R M Fontes
There are 2.5 million cases of snakebite per year and approximately 100,000 at 150,000 deaths. Thus, it is considered an important public health problem by the World Health Organization. Snakes from the Bothrops genus may cause severe local effects in the victims, so it is important to develop inhibitors to treat local effects in patients. In addition, approximately 30 different species of bothropic snakes have been described that may present differences in their venom composition. Small structural differences in the venom proteins may result in different ligands binding...
July 24, 2017: Biochimie
https://www.readbyqxmd.com/read/28743317/action-of-natural-phytosanitary-products-on-bacillus-thuringiensis-subsp-kurstaki-s-1905
#7
E R Lozano, P M O J Neves, L F A Alves, M Potrich, G F L T Vilas-Bôas, R G Monnerat
The objective of this study was to evaluate the effects of natural phytosanitary products (NPs) on spores and crystals of Bacillus thuringiensis subsp. kurstaki S-1905 (Btk S-1905). For the spore assay, NPs and bacteria were applied in combination and individually. For the combined application, Btk S-1905 + NP mixtures were inoculated on nutrient agar (NA), and for the separate applications, the NPs were spread on NA plates, which were later inoculated with the pathogen. The number of colony-forming units (CFU) per milliliter was quantified after 18 h of incubation...
July 26, 2017: Bulletin of Entomological Research
https://www.readbyqxmd.com/read/28720548/pxapn5-serves-as-a-functional-receptor-of-cry2ab-in-plutella-xylostella-l-and-its-binding-domain-analysis
#8
Zhi-Zhen Pan, Lian Xu, Bo Liu, Jing Zhang, Zheng Chen, Qing-Xi Chen, Yu-Jing Zhu
Lepidopteran midgut aminopeptidases N (APNs) are widely studied for their potential roles as one of the receptors for the Bacillus thuringiensis (Bt) crystal insecticidal toxins. In the present study, a loss of function analyses by RNAi (RNA interference) silencing of the Plutella xylostella APN5 (PxAPN5), a binding protein of Cry2Ab, were performed. The knocking down of PxAPN5 in P. xylostella larvae greatly reduced their susceptibility to Cry2Ab and led to a decrease of Cry2Ab binding to P. xylostella midgut...
July 15, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28718923/using-homology-modeling-to-interrogate-binding-affinity-in-neutralization-of-ricin-toxin-by-a-family-of-single-domain-antibodies
#9
Andrea Bazzoli, David J Vance, Michael J Rudolph, Yinghui Rong, Siva Krishna Angalakurthi, Ronald T Toth, C Russell Middaugh, David B Volkin, David D Weis, John Karanicolas, Nicholas J Mantis
In this report we investigated, within a group of closely related single domain camelid antibodies (VH Hs), the relationship between binding affinity and neutralizing activity as it pertains to ricin, a fast-acting toxin and biothreat agent. The V1C7-like VH Hs (V1C7, V2B9, V2E8, and V5C1) are similar in amino acid sequence, but differ in their binding affinities and toxin-neutralizing activities. Using the X-ray crystal structure of V1C7 in complex with ricin's enzymatic subunit (RTA) as a template, Rosetta-based homology modeling coupled with energetic decomposition led us to predict that a single pairwise interaction between Arg29 on V5C1 and Glu67 on RTA was responsible for the difference in ricin toxin binding affinity between V1C7, a weak neutralizer, and V5C1, a moderate neutralizer...
July 18, 2017: Proteins
https://www.readbyqxmd.com/read/28710264/two-novel-dissimilar-crystal-proteins-cry5ca1-and-cry5da1-synergistically-act-against-meloidogyne-incognita-and-delay-cry5ba-based-nematode-resistance
#10
Ce Geng, Yingying Liu, Miaomiao Li, Zhen Tang, Sajid Muhammad, Jinshui Zheng, Danfeng Wan, Donghai Peng, Lifang Ruan, Ming Sun
Cry proteins of Bacillus thuringiensis have been successfully used as biopesticides and transgenic crops throughout the world. However, resources against the most serious agricultural pathogens, plant root-knot nematodes, are limited. The genomes of several highly nematicidal virulent Bt strains from our laboratory have been sequenced, facilitating the identification of novel Cry proteins and other virulence factors. We identified two novel Cry proteins, Cry5Ca1 and Cry5Da1, that exhibit high toxicity against Meloidogyne incognita Using the Caenorhabditis elegans model, both Cry5 toxins showed to negatively affect nematode lifespan, fertility and survival...
July 14, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28705932/use-of-a-neutralizing-antibody-helps-identify-structural-features-critical-for-binding-of-clostridium-difficile-toxin-tcda-to-the-host-cell-surface
#11
Heather K Kroh, Ramyavardhanee Chandrasekaran, Kim Rosenthal, Rob Woods, Xiaofang Jin, Melanie D Ohi, Andrew C Nyborg, G Jonah Rainey, Paul Warrener, Benjamin W Spiller, D Borden Lacy
Clostridium difficile is a clinically significant pathogen that causes mild-to-severe (and often recurrent) colon infections. Disease symptoms stem from the activities of two large, multi-domain toxins known as TcdA and TcdB. The toxins can bind, enter, and perturb host cell function through a multi-step mechanism of receptor binding, endocytosis, pore formation, autoproteolysis, and glucosyltransferase-mediated modification of host substrates. Monoclonal antibodies that neutralize toxin activity provide a survival benefit in preclinical animal models and prevent recurrent infections in human clinical trials...
July 13, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28699724/toxicity-of-bacillus-thuringiensis-cry2ab-and-the-inheritance-of-cry2ab-resistance-in-the-pink-bollworm-pectinophora-gossypiella-saunders
#12
P A Malthankar, G T Gujar
Though the insecticidal crystal (Cry) proteins produced by Bacillus thuringiensis (Bt) are effective against insect pests, evolution of resistance remains an issue of great concern. Here, we explored the ability of pink bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae), a key pest of cotton, to evolve resistance to Cry2Ab and characterized it in terms of inheritance. Sixteen day bioassay of Bt Cry2Ab toxin against 5-day old pink bollworm larvae showed median lethal concentration (LC(50)) ranging 0...
September 2016: Indian Journal of Experimental Biology
https://www.readbyqxmd.com/read/28650463/type-vi-secretion-tssk-baseplate-protein-exhibits-structural-similarity-with-phage-receptor-binding-proteins-and-evolved-to-bind-the-membrane-complex
#13
Van Son Nguyen, Laureen Logger, Silvia Spinelli, Pierre Legrand, Thi Thanh Huyen Pham, Thi Trang Nhung Trinh, Yassine Cherrak, Abdelrahim Zoued, Aline Desmyter, Eric Durand, Alain Roussel, Christine Kellenberger, Eric Cascales, Christian Cambillau
The type VI secretion system (T6SS) is a multiprotein machine widespread in Gram-negative bacteria that delivers toxins into both eukaryotic and prokaryotic cells. The mechanism of action of the T6SS is comparable to that of contractile myophages. The T6SS builds a tail-like structure made of an inner tube wrapped by a sheath, assembled under an extended conformation. Contraction of the sheath propels the inner tube towards the target cell. The T6SS tail is assembled on a platform-the baseplate-which is functionally similar to bacteriophage baseplates...
June 26, 2017: Nature Microbiology
https://www.readbyqxmd.com/read/28645943/the-structure-of-the-tetanus-toxin-reveals-ph-mediated-domain-dynamics
#14
Geoffrey Masuyer, Julian Conrad, Pål Stenmark
The tetanus neurotoxin (TeNT) is a highly potent toxin produced by Clostridium tetani that inhibits neurotransmission of inhibitory interneurons, causing spastic paralysis in the tetanus disease. TeNT differs from the other clostridial neurotoxins by its unique ability to target the central nervous system by retrograde axonal transport. The crystal structure of the tetanus toxin reveals a "closed" domain arrangement stabilised by two disulphide bridges, and the molecular details of the toxin's interaction with its polysaccharide receptor...
August 2017: EMBO Reports
https://www.readbyqxmd.com/read/28597156/molecular-characterization-of-indigenous-bacillus-thuringiensis-strains-isolated-from-kashmir-valley
#15
A L Reyaz, L Gunapriya, P Indra Arulselvi
Bacillus thuringiensis (Bt) being an eco-friendly bioinsecticide is effectively used in pest management strategies and, therefore, isolation and identification of new strains effective against a broad range of target pests is important. In the present study, new indigenous B. thuringiensis strains were isolated and investigated so that these could be used as an alternative and/or support the current commercial strains/cry proteins in use. For this, 159 samples including soil, leaf and spider webs were collected from ten districts of Kashmir valley (India)...
June 2017: 3 Biotech
https://www.readbyqxmd.com/read/28580925/crystal-structure-of-the-multiple-antibiotic-resistance-regulator-marr-from-clostridium-difficile
#16
J W Peng, H Yuan, X S Tan
Regulators of multiple antibiotic resistance (MarRs) are key players against toxins in prokaryotes. MarR homologues have been identified in many bacterial and archaeal species which pose daunting antibiotic resistance issues that threaten public health. The continuous prevalence of Clostridium difficile infection (CDI) throughout the world is associated with the abuse of antibiotics, and antibiotic treatments of CDI have limited effect. In the genome of C. difficile strain 630, the marR gene (ID 4913953) encodes a MarR protein...
June 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/28575388/functional-details-of-the-mycobacterium-tuberculosis-vapbc26-toxin-antitoxin-system-based-on-a-structural-study-insights-into-unique-binding-and-antibiotic-peptides
#17
Sung-Min Kang, Do-Hee Kim, Ki-Young Lee, Sung Jean Park, Hye-Jin Yoon, Sang Jae Lee, Hookang Im, Bong-Jin Lee
Toxin-antitoxin (TA) systems are essential for bacterial persistence under stressful conditions. In particular, Mycobacterium tuberculosis express VapBC TA genes that encode the stable VapC toxin and the labile VapB antitoxin. Under normal conditions, these proteins interact to form a non-toxic TA complex, but the toxin is activated by release from the antitoxin in response to unfavorable conditions. Here, we present the crystal structure of the M. tuberculosis VapBC26 complex and show that the VapC26 toxin contains a pilus retraction protein (PilT) N-terminal (PIN) domain that is essential for ribonuclease activity and that, the VapB26 antitoxin folds into a ribbon-helix-helix DNA-binding motif at the N-terminus...
May 31, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28562017/toxic-aromatics-induced-responsive-facets-for-a-pore-surface-functionalized-luminescent-coordination-polymer
#18
Biplab Manna, Shivani Sharma, Soumya Mukherjee, Aamod V Desai, Sujit K Ghosh
A luminescent coordination polymer was synthesized based on a linker prefunctionalization-based design principle coupled with an appropriate template selection protocol adopted during crystallization. Luminescent linker derived photoluminescence emission signature together with the reversibly dynamic host polymer exhibited a unique response toward environmentally toxic aromatics in the solid state, arguably crucial for the designed development of toxin-responsive solid materials.
May 31, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28539625/towards-new-cholera-prophylactics-and-treatment-crystal-structures-of-bacterial-enterotoxins-in-complex-with-gm1-mimics
#19
Julie Elisabeth Heggelund, Alasdair Mackenzie, Tobias Martinsen, Joel Benjamin Heim, Pavel Cheshev, Anna Bernardi, Ute Krengel
Cholera is a life-threatening disease in many countries, and new drugs are clearly needed. C-glycosidic antagonists may serve such a purpose. Here we report atomic-resolution crystal structures of three such compounds in complexes with the cholera toxin. The structures give unprecedented atomic details of the molecular interactions and show how the inhibitors efficiently block the GM1 binding site. These molecules are well suited for development into low-cost prophylactic drugs, due to their relatively easy synthesis and their resistance to glycolytic enzymes...
May 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28485498/plasmonic-nanoparticles-decorated-diatomite-biosilica-extending-the-horizon-of-on-chip-chromatography-and-label-free-biosensing
#20
Xianming Kong, Erwen Li, Kenny Squire, Ye Liu, Bo Wu, Li-Jing Cheng, Alan X Wang
Diatomite consists of fossilized remains of ancient diatoms and is a type of naturally abundant photonic crystal biosilica with multiple unique physical and chemical functionalities. In this paper, we explored the fluidic properties of diatomite as the matrix for on-chip chromatography and, simultaneously, the photonic crystal effects to enhance the plasmonic resonances of metallic nanoparticles for surface-enhanced Raman scattering (SERS) biosensing. The plasmonic nanoparticle-decorated diatomite biosilica provides a lab-on-a-chip capability to separate and detect small molecules from mixture samples with ultra-high detection sensitivity down to 1 ppm...
May 9, 2017: Journal of Biophotonics
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