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https://www.readbyqxmd.com/read/29027367/the-parasporal-crystals-of-bacillus-pumilus-strain-15-1-a-potential-virulence-factor
#1
Diana C Garcia-Ramon, Colin Berry, Carmen Tse, Alberto Fernández-Fernández, Antonio Osuna, Susana Vílchez
Bacillus pumilus strain 15.1 was previously found to cause larval mortality in the Med-fly Ceratitis capitata and was shown to produce crystals in association with the spore. As parasporal crystals are well-known as invertebrate-active toxins in entomopathogenic bacteria such as Bacillus thuringiensis (Cry and Cyt toxins) and Lysinibacillus sphaericus (Bin and Cry toxins), the B. pumilus crystals were characterized. The crystals were composed of a 45 kDa protein that was identified as an oxalate decarboxylase by peptide mass fingerprinting, N-terminal sequencing and by comparison with the genome sequence of strain 15...
October 12, 2017: Microbial Biotechnology
https://www.readbyqxmd.com/read/29019656/adsorption-of-insecticidal-crystal-protein-cry11aa-onto-nano-mg-oh-2-effects-on-bioactivity-and-anti-ultraviolet-ability
#2
Xiaohong Pan, Zhangyan Xu, Lan Li, Enshi Shao, Saili Chen, Tengzhou Huang, Zhi Chen, Wenhua Rao, Tianpei Huang, Lingling Zhang, Songqing Wu, Xiong Guan
The traditional Bacillus thuringiensis (Bt) formulation for field applications are not resistant to harsh environmental conditions. Hence, the active ingredients of the Bt bioinsecticides could degrade quickly and has low anti-ultraviolet ability in the field, which significantly limits its practical application. In the present study, we developed an efficient and stable delivery system for Bt Cry11Aa toxins. We coated Cry11Aa proteins with Mg(OH)2 nanoparticles (MHNPs), and then assessed the effects of MHNPs on bioactivity and anti-ultraviolet ability of the Cry11Aa proteins...
October 11, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29018619/alpha-arylphorin-is-a-mitogen-in-the-heliothis-virescens-midgut-cell-secretome-upon-cry1ac-intoxication
#3
Anais Castagnola, Jerreme Jackson, Omaththage P Perera, Cris Oppert, Shigetoshi Eda, Juan Luis Jurat-Fuentes
Insecticidal crystal (Cry) proteins produced by the bacterium Bacillus thuringiensis (Bt) target cells in the midgut epithelium of susceptible larvae. While the mode of action of Cry toxins has been extensively investigated, the midgut response to Cry intoxication and its regulation are not well characterized. In this work, we describe the secreted proteome (secretome) of primary mature midgut cell cultures from Heliothis virescens larvae after exposure to Cry1Ac toxin compared to control buffer treatment. The Cry1Ac-induced secretome caused higher proliferation and differentiation and an overall reduction in total cell mortality over time in primary H...
2017: PeerJ
https://www.readbyqxmd.com/read/28986943/crystal-structure-of-mycobacterium-tuberculosis-vapc20-toxin-and-its-interactions-with-cognate-antitoxin-vapb20-suggest-a-model-for-toxin-antitoxin-assembly
#4
Amar Deep, Soni Kaundal, Sakshi Agarwal, Ramandeep Singh, Krishan Gopal Thakur
VapBCs, virulence-associated proteins, are the most abundant type II toxin-antitoxin (TA) systems in prokaryotes. Under normal conditions, toxin and antitoxin interact to form a heterooctameric complex, which upon binding to operator sites, inhibits their own expression. Under stress conditions, the VapB antitoxin is degraded by cellular proteases to release a free VapC toxin, which in turn inhibits cell growth mainly by targeting protein translation. However, the intermediate steps involved in the assembly of the heterooctameric complex have not been resolved...
October 7, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28979890/structure-based-prototype-peptides-targeting-the-pseudomonas-aeruginosa-type-vi-secretion-system-effector-as-a-novel-antibacterial-strategy
#5
Xiaopan Gao, Zhixia Mu, Bo Qin, Yicheng Sun, Sheng Cui
The type VI secretion system (T6SS) secretes numerous toxins for bacteria-bacteria competition. TplE is a newly identified trans-kingdom toxin secreted by the T6SS in Pseudomonas aeruginosa, while TplEi neutralizes the toxic effect of TplE to protect bacteria autointoxication. Blocking the interaction of TplE-TplEi could unleash the toxin, causing bacterial cell death. In this study, we applied a crystallographic approach to design a structural-based antimicrobial peptides targeting the interaction of TplE and TplEi...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28970335/fusicoccin-activates-kat1-channels-by-stabilizing-their-interaction-with-14-3-3-proteins
#6
Andrea Saponaro, Alessandro Porro, Antonio Chaves-Sanjuan, Marco Nardini, Oliver Rauh, Gerhard Thiel, Anna Moroni
Plants acquire potassium (K+) ions for cell growth and movement via regulated diffusion through K+ channels. Here we present crystallographic and functional data showing that the K+ inward rectifier KAT1 channel is regulated by 14-3-3 proteins and further modulated by the phytotoxin fusicoccin, in analogy to the H+-ATPase. We identified a 14-3-3 mode III binding site at the very C-terminus of KAT1 and co-crystallized it with tobacco 14-3-3 proteins to describe the protein complex at atomic detail. Validation of this interaction by electrophysiology shows that 14-3-3 binding augments KAT1 conductance by increasing the maximal current and by positively shifting the voltage-dependency of gating...
September 29, 2017: Plant Cell
https://www.readbyqxmd.com/read/28959866/-interaction-of-aminopeptidase-bmapn5-and-parasporal-crystal-pc-toxin-isolated-from-bacillus-bombysepticus
#7
Jianfeng Fu, Ping Lin, Tieshan Feng, Dong Cheng, Quan Zhang, Qingyou Xia, Tingcai Cheng
Aminopeptidase N (APN) belonging to zinc-dependent metalloproteinase, not only catalyzes protein proteolytic process, but also is involved in the pathogenic process as the receptor of pathogenic toxin. In Bombyx mori, APN gene family consists of 16 members, of which BmAPN4 binds trypsin-activated parasporal crystal (PC) toxin isolated from Bacillus bombysepticus (Bb). In order to verify whether or not other APNs interact with PC toxin during the pathogenesis of Bb, we cloned BmAPN5, a member of aminopeptidase family, from the silkworm midgut...
January 25, 2017: Sheng Wu Gong Cheng Xue Bao, Chinese Journal of Biotechnology
https://www.readbyqxmd.com/read/28958150/synthesis-and-characterization-of-tethered-lipid-assemblies-for-membrane-protein-reconstitution-review
#8
Rémi Veneziano, Claire Rossi, Alexandre Chenal, Catherine Brenner, Daniel Ladant, Joël Chopineau
Biological membranes and their related molecular mechanisms are essential for all living organisms. Membranes host numerous proteins and are responsible for the exchange of molecules and ions, cell signaling, and cell compartmentation. Indeed, the plasma membrane delimits the intracellular compartment from the extracellular environment and intracellular membranes. Biological membranes also play a major role in metabolism regulation and cellular physiology (e.g., mitochondrial membranes). The elaboration of membrane based biomimetic systems allows us to reconstitute and investigate, in controlled conditions, biological events occurring at the membrane interface...
September 28, 2017: Biointerphases
https://www.readbyqxmd.com/read/28940938/downregulation-of-chilo-suppressalis-alkaline-phosphatase-genes-associated-with-resistance-to-three-transgenic-bacillus-thuringiensis-rice-lines
#9
L Qiu, P Wang, T Wu, B Li, X Wang, C Lei, Y Lin, J Zhao, W Ma
Insecticidal crystal (Cry) proteins produced by the bacterium Bacillus thuringiensis are highly toxic to lepidopteran pests. Strains of transgenic rice expressing cry genes have been developed that are resistant to rice pests. Understanding the mode of action of Cry toxins in rice pests will improve our ability to use them effectively as insecticides. In this study, we tested the hypothesis that alkaline phosphatases (ALPs) are involved in Cry1A, Cry2Aa and Cry1Ca toxicity in Chilo suppressalis, an important insect pest of rice crops in China...
September 21, 2017: Insect Molecular Biology
https://www.readbyqxmd.com/read/28930630/assessing-the-structure-and-stability-of-transmembrane-oligomeric-intermediates-of-an-%C3%AE-helical-toxin
#10
Rajat Desikan, Prabal 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) are the primary vehicle for infection by several strains of bacteria. These proteins which are expressed in a water-soluble form (monomers) bind to the target membrane and conformationally transform (protomers) and self-assemble to form a multimer transmembrane pore complex through a process of oligomerization...
October 3, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28901209/the-distinct-properties-of-natural-and-gm-cry-insecticidal-proteins
#11
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/28880078/the-role-of-disulfide-bond-replacements-in-analogues-of-the-tarantula-toxin-protx-ii-and-their-effects-on-inhibition-of-the-voltage-gated-sodium-ion-channel-nav1-7
#12
Zoë V F Wright, Stephen McCarthy, Rachael Dickman, Francis E Reyes, Silvia Sanchez-Martinez, Adam Cryar, Ian Kilford, Adrian Hall, Andrew K Takle, Maya Topf, Tamir Gonen, Konstantinos Thalassinos, Alethea B Tabor
Spider venom toxins, such as Protoxin-II (ProTx-II), have recently received much attention as selective Nav1.7 channel blockers, with potential to be developed as leads for the treatment of chronic nocioceptive pain. ProTx-II is a 30-amino acid peptide with three disulfide bonds that has been reported to adopt a well-defined inhibitory cystine knot (ICK) scaffold structure. Potential drawbacks with such peptides include poor pharmacodynamics and potential scrambling of the disulfide bonds in vivo. In order to address these issues, in the present study we report the solid-phase synthesis of lanthionine-bridged analogues of ProTx-II, in which one of the three disulfide bridges is replaced with a thioether linkage, and evaluate the biological properties of these analogues...
September 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28876228/hicab-toxin-antitoxin-complex-from-escherichia-coli-expression-and-crystallization
#13
Jingsi Yang, Bingshuang Xu, Zengqiang Gao, Ke Zhou, Peng Liu, Yuhui Dong, Jianjun Zhang, Quansheng Liu
Toxin-antitoxin (TA) systems are widespread in both bacteria and archaea, where they enable cells to adapt to environmental cues. TA systems play crucial roles in various cellular processes, such as programmed cell death, cell growth, persistence and virulence. Here, two distinct forms of the type II toxin-antitoxin complex HicAB were identified and characterized in Escherichia coli K-12, and both were successfully overexpressed and purified. The two proposed forms, HicAB(L) and HicAB(S), differed in the presence or absence of a seven-amino-acid segment at the N-terminus in the antitoxin HicB...
September 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/28866859/toxin-gene-contents-and-activity-of-bacillus-thuringiensis-strains-against-two-sugarcane-borer-species-diatraea-saccharalis-f-and-d-flavipennella-box
#14
L M Silva, M C Silva, S M F A Silva, R C Alves, H A A Siqueira, E J Marques
Bacillus thuringiensis (Berliner) bears essential characteristics in the control of insect pests, such as its unique mode of action, which confers specificity and selectivity. This study assessed cry gene contents from Bt strains and their entomotoxicity against Diatraea saccharalis (F.) and Diatraea flavipennella (Box) (Lepidoptera: Crambidae). Bioassays with Bt strains were performed against neonates to evaluate their lethal and sublethal activities and were further analyzed by PCR, using primers to identify toxin genes...
September 2, 2017: Neotropical Entomology
https://www.readbyqxmd.com/read/28852435/complete-genome-sequence-of-the-nematicidal-bacillus-thuringiensis-mybt18246
#15
Jacqueline Hollensteiner, Anja Poehlein, Cathrin Spröer, Boyke Bunk, Anna E Sheppard, Philip Rosentstiel, Hinrich Schulenburg, Heiko Liesegang
10.1601/nm.5000 is a rod-shaped facultative anaerobic spore forming bacterium of the genus 10.1601/nm.4857. The defining feature of the species is the ability to produce parasporal crystal inclusion bodies, consisting of δ-endotoxins, encoded by cry-genes. Here we present the complete annotated genome sequence of the nematicidal 10.1601/nm.5000 strain MYBT18246. The genome comprises one 5,867,749 bp chromosome and 11 plasmids which vary in size from 6330 bp to 150,790 bp. The chromosome contains 6092 protein-coding and 150 RNA genes, including 36 rRNA genes...
2017: Standards in Genomic Sciences
https://www.readbyqxmd.com/read/28846375/binding-of-the-microbial-cyclic-tetrapeptide-trapoxin-a-to-the-class-i-histone-deacetylase-hdac8
#16
Nicholas J Porter, David W Christianson
Trapoxin A is a microbial cyclic tetrapeptide that is an essentially irreversible inhibitor of class I histone deacetylases (HDACs). The inhibitory warhead is the α,β-epoxyketone side-chain of (2S,9S)-2-amino-8-oxo-9,10-epoxydecanoic acid (l-Aoe), which mimics the side-chain of the HDAC substrate acetyl-l-lysine. We now report the crystal structure of the HDAC8-trapoxin A complex at 1.24 Å resolution, revealing that the ketone moiety of l-Aoe undergoes nucleophilic attack to form a zinc-bound tetrahedral gem-diolate that mimics the tetrahedral intermediate and its flanking transition states in catalysis...
September 15, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28832970/differential-binding-of-tetrodotoxin-and-its-derivatives-to-voltage-sensitive-sodium-channel-subtypes-nav-1-1-to-nav-1-7
#17
Tadaaki Tsukamoto, Yukie Chiba, Minoru Wakamori, Tomoshi Yamada, Shunsuke Tsunogae, Yuko Cho, Ryo Sakakibara, Takuya Imazu, Shouta Tokoro, Yoshiki Satake, Masaatsu Adachi, Toshio Nishikawa, Mari Yotsu-Yamashita, Keiichi Konoki
BACKGROUND AND PURPOSE: The development of subtype-selective ligands to inhibit voltage-sensitive sodium channels (VSSCs) has been attempted with the aim of developing therapeutic compounds. Tetrodotoxin is a toxin from pufferfish that strongly inhibits VSSCs. Many tetrodotoxin analogues have been identified from marine and terrestrial sources, although their specificity for particular VSSC subtypes has not been investigated. Herein, we describe the binding of 11 tetrodotoxin analogues to human VSSC subtypes Nav 1...
August 18, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28821431/bacillus-thuringiensis-cyt2aa2-binding-on-lipid-cholesterol-bilayer-depends-on-protein-concentration-and-time
#18
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/28796264/lytic-cell-death-induced-by-melittin-bypasses-pyroptosis-but-induces-nlrp3-inflammasome-activation-and-il-1%C3%AE-release
#19
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
#20
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
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