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https://www.readbyqxmd.com/read/29432487/structural-basis-of-mammalian-glycan-targeting-by-vibrio-cholerae-cytolysin-and-biofilm-proteins
#1
Swastik De, Katherine Kaus, Shada Sinclair, Brandon C Case, Rich Olson
Vibrio cholerae is an aquatic gram-negative microbe responsible for cholera, a pandemic disease causing life-threatening diarrheal outbreaks in populations with limited access to health care. Like most pathogenic bacteria, V. cholerae secretes virulence factors to assist colonization of human hosts, several of which bind carbohydrate receptors found on cell-surfaces. Understanding how pathogenic virulence proteins specifically target host cells is important for the development of treatment strategies to fight bacterial infections...
February 12, 2018: PLoS Pathogens
https://www.readbyqxmd.com/read/29371662/crystal-structure-of-lipid-a-disaccharide-synthase-lpxb-from-escherichia-coli
#2
Thomas E Bohl, Ke Shi, John K Lee, Hideki Aihara
Most Gram-negative bacteria are surrounded by a glycolipid called lipopolysaccharide (LPS), which forms a barrier to hydrophobic toxins and, in pathogenic bacteria, is a virulence factor. During LPS biosynthesis, a membrane-associated glycosyltransferase (LpxB) forms a tetra-acylated disaccharide that is further acylated to form the membrane anchor moiety of LPS. Here we solve the structure of a soluble and catalytically competent LpxB by X-ray crystallography. The structure reveals that LpxB has a glycosyltransferase-B family fold but with a highly intertwined, C-terminally swapped dimer comprising four domains...
January 25, 2018: Nature Communications
https://www.readbyqxmd.com/read/29366893/molecular-characterization-of-cry1d-133-toxin-from-bacillus-thuringiensis-strain-hd133-and-its-toxicity-against-spodoptera-littoralis
#3
Dalel BenFarhat-Touzri, Fatma Driss, Sonia Jemli, Slim Tounsi
Bacillus thuringiensis subsp. aizawai strain HD133, known by its effectiveness against Spodoptera species, produces bipyramidal crystals encompassing the insecticidal proteins Cry1Ab, Cry1Ca and Cry1D-133 in the proportions 60:37:3, respectively. In this study, we dealt with the relevance of the low rate of Cry1D-133. The cry1D-133 gene from HD133 was cloned and sequenced. Both nucleotide and amino acid sequence similarity analyses with the cry1D genes available in the GenBank database revealed that cry1D-133 is a new variant of cry1Da-type genes with 99% identity with cry1Da1...
January 20, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29350293/diversity-and-enzymatic-potentialities-of-bacillus-sp-strains-isolated-from-a-polluted-freshwater-ecosystem-in-cuba
#4
Jeny Adina Larrea-Murrell, Marcia Maria Rojas-Badia, Ivette García-Soto, Beatriz Romeu-Alvarez, Tristano Bacchetti, Annika Gillis, Ana Karina Boltes-Espinola, Mayra Heydrich-Perez, Daysi Lugo-Moya, Jacques Mahillon
Genotypic and phenotypic characterization of Bacillus spp. from polluted freshwater has been poorly addressed. The objective of this research was to determine the diversity and enzymatic potentialities of Bacillus spp. strains isolated from the Almendares River. Bacilli strains from a polluted river were characterized by considering the production of extracellular enzymes using API ZYM. 14 strains were selected and identified using 16S rRNA, gyrB and aroE genes. Genotypic diversity of the Bacillus spp. strains was evaluated using pulsed field gel electrophoresis...
January 19, 2018: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/29287778/structural-evidence-for-a-fatty-acid-independent-myotoxic-mechanism-for-a-phospholipase-a2-like-toxin
#5
Guilherme H M Salvador, Juliana I Dos Santos, Rafael J Borges, Marcos R M Fontes
The myotoxic mechanism for PLA2-like toxins has been proposed recently to be initiated by an allosteric change induced by a fatty acid binding to the protein, leading to the alignment of the membrane docking site (MDoS) and membrane disrupting site (MDiS). Previous structural studies performed by us demonstrated that MjTX-II, a PLA2-like toxin isolated from Bothrops moojeni, presents a different mode of ligand-interaction, with its hydrophobic channels caused by natural amino acid substitutions and an insertion...
December 26, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29208763/characterization-of-the-catalytic-signature-of-scabin-toxin-a-dna-targeting-adp-ribosyltransferase
#6
Bronwyn Lyons, Miguel R Lugo, Stephanie Carlin, Taylor Lidster, A Rod Merrill
Scabin was previously identified as a novel DNA-targeting mono-ADP-ribosyltransferase toxin from the plant pathogen 87.22 strain of Streptomyces scabies Scabin is a member of the Pierisin-like subgroup of mono-ADP-ribosyltransferase toxins, since it targets DNA. An in-depth characterization of both the glycohydrolase and transferase enzymatic activities of Scabin was conducted. Several protein variants were developed based on an initial Scabin·DNA molecular model. Consequently, three residues were deemed important for DNA binding and transferase activity...
December 5, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/29189732/identification-and-characterization-of-hyphantria-cunea-aminopeptidase-n-as-a-binding-protein-of-bacillus-thuringiensis-cry1ab35-toxin
#7
Yakun Zhang, Dan Zhao, Xiaoping Yan, Wei Guo, Yajun Bao, Wei Wang, Xiaoyun Wang
The fall webworm, Hyphantria cunea (Drury) is a major invasive pest in China. Aminopeptidase N (APN) isoforms in lepidopteran larvae midguts are known for their involvement in the mode of action of insecticidal crystal (Cry) proteins from Bacillus thuringiensis. In the present work, we identified a putative Cry1Ab toxin-binding protein, an APN isoform designated HcAPN3, in the midgut of H. cunea by ligand blot and mass spectrometry. HcAPN3 was highly expressed throughout all larval developmental stages and was abundant in the midgut and hindgut tissues...
November 30, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29158482/structural-basis-for-the-unique-ganglioside-and-cell-membrane-recognition-mechanism-of-botulinum-neurotoxin-dc
#8
Sicai Zhang, Ronnie P-A Berntsson, William H Tepp, Liang Tao, Eric A Johnson, Pål Stenmark, Min Dong
Botulinum neurotoxins (BoNTs), the most potent toxins known, are potential bioterrorism agents. It is well established that all seven serotypes of BoNTs (BoNT/A-G) require complex gangliosides as co-receptors. Here, we report that BoNT/DC, a presumed mosaic toxin between BoNT/D and BoNT/C1, binds and enters efficiently into neurons lacking complex gangliosides and shows no reduction in toxicity in mice deficient in complex gangliosides. The co-crystal structure of BoNT/DC with sialyl-Thomsen-Friedenreich antigen (Sialyl-T) suggests that BoNT/DC recognizes only the sialic acid, but not other moieties in gangliosides...
November 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/29133347/analysis-of-the-human-mucosal-response-to-cholera-reveals-sustained-activation-of-innate-immune-signaling-pathways
#9
Daniel L Bourque, Taufiqur Rahman Bhuiyan, Diane P Genereux, Rasheduzzaman Rashu, Crystal N Ellis, Fahima Chowdhury, Ashraful I Khan, Nur Haq Alam, Anik Paul Lazina Hossain, Leslie M Mayo-Smith, Richelle C Charles, Ana A Weil, Regina C LaRocque, Stephen B Calderwood, Edward T Ryan, Elinor K Karlsson, Firdausi Qadri, Jason B Harris
To better understand the innate immune response to Vibrio cholerae infection, we tracked gene expression in the duodenal mucosa of eleven Bangladeshi adults with cholera, using biopsies obtained immediately after rehydration and at 30 and 180 days later. We identified differentially expressed genes and performed an analysis to predict differentially regulated pathways and upstream regulators. During acute cholera, there was a broad increase in the expression of genes associated with innate immunity, including activation of the NF-κB, MAPK, and TLR-mediated signaling pathways, which unexpectedly persisted even 30 days after infection...
November 13, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/29124866/characterization-of-the-toxin-plx2a-a-rhoa-targeting-adp-ribosyltransferase-produced-by-the-honey-bee-pathogen-paenibacillus-larvae
#10
Julia Ebeling, Anne Fünfhaus, Henriette Knispel, Dan Krska, Ravikiran Ravulapalli, Kayla A Heney, Miguel R Lugo, A Rod Merrill, Elke Genersch
The toxin Plx2A is an important virulence factor of Paenibacillus larvae, the etiological agent of American Foulbrood, the most destructive bacterial disease of honey bees. Biochemical and functional analyses as well as the crystal structure of Plx2A revealed that it belongs to the C3 mono-ADP-ribosylating toxin subgroup. RhoA was identified as the cellular target of Plx2A activity. The kinetic parameters (KM, kcat) were established for both the transferase and glycohydrolase (GH) reactions. When expressed in yeast, Plx2A was cytotoxic for eukaryotic cells and catalytic variants confirmed that the cytotoxicity of Plx2A depends on its enzymatic activity...
November 10, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/29111354/three-gpi-anchored-alkaline-phosphatases-are-involved-in-the-intoxication-of-cry1ca-toxin-to-spodoptera-exigua-larvae
#11
Xiang-Liang Ren, Hong-Yan Hu, Wei-Li Jiang, Xiao-Yan Ma, Ya-Jie Ma, Guo-Qing Li, Yan Ma
Glycosylphosphatidylinositol (GPI)-anchored alkaline phosphatase (ALP) isoforms are crucial for the intoxication of crystal proteins (Cry) to several insect species. We cloned five SeALPs from the larval midgut of Spodoptera exigua, a major pest of many crops. All five SeALPs contain a signal peptide at the N-terminus, a phosphatase domain, and a GPI-anchor site at the C-terminus. Additionally, the sequences encode two or three potential N-glycosylation sites. The five SeALPs were highly expressed at the larval stage, especially in the larval gut or Malpighian tubules...
October 27, 2017: Journal of Invertebrate Pathology
https://www.readbyqxmd.com/read/29074967/a-proteomic-analysis-provides-novel-insights-into-the-stress-responses-of-caenorhabditis-elegans-towards-nematicidal-cry6a-toxin-from-bacillus-thuringiensis
#12
Bing Wang, Haiwen Wang, Jing Xiong, Qiaoni Zhou, Huan Wu, Liqiu Xia, Lin Li, Ziquan Yu
Cry6A represents a novel family of nematicidal crystal proteins from Bacillus thuringiensis. It has distinctive architecture as well as mechanism of action from Cry5B, a highly focused family of nematicidal crystal proteins, and even from other insecticidal crystal proteins containing the conserved three-domain. However, how nematode defends against Cry6A toxin remains obscure. In this study, the global defense pattern of Caenorhabditis elegans against Cry6Aa2 toxin was investigated by proteomic analysis. In response to Cry6Aa2, 12 proteins with significantly altered abundances were observed from worms, participating in innate immune defense, insulin-like receptor (ILR) signaling pathway, energy metabolism, and muscle assembly...
October 26, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29061301/stoichiometry-and-mechanistic-implications-of-the-macab-tolc-tripartite-efflux-pump
#13
Inseong Jo, Seokho Hong, Minho Lee, Saemee Song, Jin-Sik Kim, Alok K Mitra, Jaekyung Hyun, Kangseok Lee, Nam-Chul Ha
The MacAB-TolC tripartite efflux pump is involved in resistance to macrolide antibiotics and secretion of protein toxins in many Gram-negative bacteria. The pump spans the entire cell envelope and operates by expelling substances to extracellular space. X-ray crystal and electron microscopic structures have revealed the funnel-like MacA hexamer in the periplasmic space and the cylindrical TolC trimer. Nonetheless, the inner membrane transporter MacB still remains ambiguous in terms of its oligomeric state in the functional complex...
October 20, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/29027367/the-parasporal-crystals-of-bacillus-pumilus-strain-15-1-a-potential-virulence-factor
#14
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
#15
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) formulations 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 23, 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
#16
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
#17
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
#18
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
#19
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
#20
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
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