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https://www.readbyqxmd.com/read/28539625/towards-new-cholera-prophylactics-and-treatment-crystal-structures-of-bacterial-enterotoxins-in-complex-with-gm1-mimics
#1
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
#2
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
https://www.readbyqxmd.com/read/28481307/histopathological-effects-of-bt-and-tcda-insecticidal-proteins-on-the-midgut-epithelium-of-western-corn-rootworm-larvae-diabrotica-virgifera-virgifera
#3
Andrew J Bowling, Heather E Pence, Huarong Li, Sek Yee Tan, Steven L Evans, Kenneth E Narva
Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is a major corn pest in the United States, causing annual losses of over $1 billion. One approach to protect against crop loss by this insect is the use of transgenic corn hybrids expressing one or more crystal (Cry) proteins derived from Bacillus thuringiensis. Cry34Ab1 and Cry35Ab1 together comprise a binary insecticidal toxin with specific activity against WCR. These proteins have been developed as insect resistance traits in commercialized corn hybrids resistant to WCR feeding damage...
May 8, 2017: Toxins
https://www.readbyqxmd.com/read/28470711/carbohydrate-recognition-by-the-rhamnose-binding-lectin-sul-i-with-a-novel-three-domain-structure-isolated-from-the-venom-of-globiferous-pedicellariae-of-the-flower-sea-urchin-toxopneustes-pileolus
#4
Tomomitsu Hatakeyama, Ayaka Ichise, Hideaki Unno, Shuichiro Goda, Tatsuya Oda, Hiroaki Tateno, Jun Hirabayashi, Hitomi Sakai, Hideyuki Nakagawa
The globiferous pedicellariae of the venomous sea urchin Toxopneustes pileolus contains several biologically active proteins. We have cloned the cDNA of one of the toxin components, SUL-I, which is a rhamnose-binding lectin that acts as a mitogen through binding to carbohydrate chains on target cells. Recombinant SUL-I (rSUL-I) was produced in Escherichia coli cells, and its carbohydrate-binding specificity was examined with the glycoconjugate microarray analysis, which suggested that potential target carbohydrate structures are galactose-terminated N-glycans...
May 3, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28465678/protein-species-quantitative-venomics-looking-through-a-crystal-ball
#5
REVIEW
Juan J Calvete, Daniel Petras, Francisco Calderón-Celis, Bruno Lomonte, Jorge Ruiz Encinar, Alfredo Sanz-Medel
In this paper we discuss recent significant developments in the field of venom research, specifically the emergence of top-down proteomic applications that allow achieving compositional resolution at the level of the protein species present in the venom, and the absolute quantification of the venom proteins (the term "protein species" is used here to refer to all the different molecular forms in which a protein can be found. Please consult the special issue of Jornal of Proteomics "Towards deciphering proteomes via the proteoform, protein speciation, moonlighting and protein code concepts" published in 2016, vol...
2017: Journal of Venomous Animals and Toxins Including Tropical Diseases
https://www.readbyqxmd.com/read/28462954/metal-organic-frameworks-functional-luminescent-and-photonic-materials-for-sensing-applications
#6
REVIEW
William P Lustig, Soumya Mukherjee, Nathan D Rudd, Aamod V Desai, Jing Li, Sujit K Ghosh
Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) are open, crystalline supramolecular coordination architectures with porous facets. These chemically tailorable framework materials are the subject of intense and expansive research, and are particularly relevant in the fields of sensory materials and device engineering. As the subfield of MOF-based sensing has developed, many diverse chemical functionalities have been carefully and rationally implanted into the coordination nanospace of MOF materials...
May 2, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28433497/clostridium-difficile-toxin-glucosyltransferase-domains-in-complex-with-a-non-hydrolyzable-udp-glucose-analogue
#7
Joseph W Alvin, D Borden Lacy
Clostridium difficile is the leading cause of hospital-acquired diarrhea and pseudomembranous colitis worldwide. The organism produces two homologous toxins, TcdA and TcdB, which enter and disrupt host cell function by glucosylating and thereby inactivating key signalling molecules within the host. As a toxin-mediated disease, there has been a significant interest in identifying small molecule inhibitors of the toxins' glucosyltransferase activities. This study was initiated as part of an effort to identify the mode of inhibition for a small molecule inhibitor of glucosyltransferase activity called apigenin...
April 19, 2017: Journal of Structural Biology
https://www.readbyqxmd.com/read/28414448/substrate-profiling-and-high-resolution-co-complex-crystal-structure-of-a-secreted-c11-protease-conserved-across-commensal-bacteria
#8
Emily J Roncase, Clara Moon, Sandip Chatterjee, Gonzalo E González-Páez, Charles S Craik, Anthony J O'Donoghue, Dennis W Wolan
Cysteine proteases are among the most abundant hydrolytic enzymes produced by bacteria, and this diverse family of proteins have significant biological roles in bacterial viability and environmental interactions. Members of the clostripain-like (C11) family of cysteine proteases from commensal gut bacterial strains have recently been shown to mediate immune responses by inducing neutrophil phagocytosis and activating bacterial pathogenic toxins. Development of substrates, inhibitors, and probes that target C11 proteases from enteric bacteria will help to establish the role of these proteins at the interface of the host and microbiome in health and disease...
April 27, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28400471/a-novel-tarantula-toxin-stabilizes-the-deactivated-voltage-sensor-of-bacterial-sodium-channel
#9
Cheng Tang, Xi Zhou, Phuong Tran Nguyen, Yunxiao Zhang, Zhaotun Hu, Changxin Zhang, Vladimir Yarov-Yarovoy, Paul G DeCaen, Songping Liang, Zhonghua Liu
Voltage-gated sodium channels (NaVs) are activated by transiting the voltage sensor from the deactivated to the activated state. The crystal structures of several bacterial NaVs have captured the voltage sensor module (VSM) in an activated state, but structure of the deactivated voltage sensor remains elusive. In this study, we sought to identify peptide toxins stabilizing the deactivated VSM of bacterial NaVs. We screened fractions from several venoms and characterized a cystine knot toxin called JZTx-27 from the venom of tarantula Chilobrachys jingzhao as a high-affinity antagonist of the prokaryotic NaVs nonselective voltage-gated, Bacillus alcalophilus (NsVBa) and bacterial sodium channel from Bacillus halodurans(NaChBac) (IC50 = 112 nM and 30 nM, respectively)...
April 11, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28398546/the-cdi-toxin-of-yersinia-kristensenii-is-a-novel-bacterial-member-of-the-rnase-a-superfamily
#10
Gaëlle Batot, Karolina Michalska, Greg Ekberg, Ervin M Irimpan, Grazyna Joachimiak, Robert Jedrzejczak, Gyorgy Babnigg, Christopher S Hayes, Andrzej Joachimiak, Celia W Goulding
Contact-dependent growth inhibition (CDI) is an important mechanism of inter-bacterial competition found in many Gram-negative pathogens. CDI+ cells express cell-surface CdiA proteins that bind neighboring bacteria and deliver C-terminal toxin domains (CdiA-CT) to inhibit target-cell growth. CDI+ bacteria also produce CdiI immunity proteins, which specifically neutralize cognate CdiA-CT toxins to prevent self-inhibition. Here, we present the crystal structure of the CdiA-CT/CdiIYkris complex from Yersinia kristensenii ATCC 33638...
May 19, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28351618/structure-of-the-mazf-mt9-toxin-a-trna-specific-endonuclease-from-mycobacterium-tuberculosis
#11
Ran Chen, Jie Tu, Zhihui Liu, Fanrong Meng, Pinyun Ma, Zhishan Ding, Chengwen Yang, Lei Chen, Xiangyu Deng, Wei Xie
Tuberculosis (TB) is a severe disease caused by Mycobacterium tuberculosis (M. tb) and the well-characterized M. tb MazE/F proteins play important roles in stress adaptation. Recently, the MazF-mt9 toxin has been found to display endonuclease activities towards tRNAs but the mechanism is unknown. We hereby present the crystal structure of apo-MazF-mt9. The enzyme recognizes tRNA(Lys) with a central UUU motif within the anticodon loop, but is insensitive to the sequence context outside of the loop. Based on our crystallographic and biochemical studies, we identified key residues for catalysis and proposed the potential tRNA-binding site...
March 25, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28350474/detachment-of-membrane-bound-virions-by-competitive-ligand-binding-induced-receptor-depletion
#12
Nagma Parveen, Stephan Block, Vladimir P Zhdanov, Gustaf E Rydell, Fredrik Höök
Multivalent receptor-mediated interactions between virions and a lipid membrane can be weakened using competitive nonpathogenic ligand binding. In particular, the subsequent binding of such ligands can induce detachment of bound virions, a phenomenon of crucial relevance for the development of new antiviral drugs. Focusing on the simian virus 40 (SV40) and recombinant cholera toxin B subunit (rCTB), and using (monosialotetrahexosyl)ganglioside (GM1) as their common receptor in a supported lipid bilayer (SLB), we present the first detailed investigation of this phenomenon by employing the quartz crystal microbalance with dissipation (QCM-D) and total internal reflection fluorescence (TIRF) microscopy assisted 2D single particle tracking (SPT) techniques...
April 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28334932/ribosome-dependent-vibrio-cholerae-mrnase-higb2-is-regulated-by-a-%C3%AE-strand-sliding-mechanism
#13
San Hadži, Abel Garcia-Pino, Sarah Haesaerts, Dukas Jurenas, Kenn Gerdes, Jurij Lah, Remy Loris
Toxin-antitoxin (TA) modules are small operons involved in bacterial stress response and persistence. higBA operons form a family of TA modules with an inverted gene organization and a toxin belonging to the RelE/ParE superfamily. Here, we present the crystal structures of chromosomally encoded Vibrio cholerae antitoxin (VcHigA2), toxin (VcHigB2) and their complex, which show significant differences in structure and mechanisms of function compared to the higBA module from plasmid Rts1, the defining member of the family...
May 5, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28330277/classical-and-bayesian-predictions-applied-to-bacillus-toxin-production
#14
Karim Ennouri, Rayda Ben Ayed, Maura Mazzarello, Ennio Ottaviani, Fathi Hertelli, Hichem Azzouz
Bacillus thuringiensis is a bacterium with unusual properties that make it useful for pest control in ecoagriculture. It can form a parasporal crystal containing polypeptides (also called delta-endotoxins). These entomopathogenic toxins are made during the stationary phase of the bacterial growth cycle and were initially characterized as an insect pathogen. Nowadays, the use of saturated two-level designs is very popular. This method is especially used in industrial applications where the cost of experiments is expensive...
December 2016: 3 Biotech
https://www.readbyqxmd.com/read/28298445/the-structure-and-function-of-mycobacterium-tuberculosis-mazf-mt6-toxin-provide-insights-into-conserved-features-of-mazf-endonucleases
#15
Eric D Hoffer, Stacey J Miles, Christine M Dunham
Toxin-antitoxin systems are ubiquitous in prokaryotic and archaeal genomes and regulate growth in response to stress. Escherichia coli contains at least 36 putative toxin-antitoxin gene pairs, and some pathogens such as Mycobacterium tuberculosis have over 90 toxin-antitoxin operons. E. coli MazF cleaves free mRNA after encountering stress, and nine M. tuberculosis MazF family members cleave mRNA, tRNA, or rRNA. Moreover, M. tuberculosis MazF-mt6 cleaves 23S rRNA Helix 70 to inhibit protein synthesis. The overall tertiary folds of these MazFs are predicted to be similar, and therefore, it is unclear how they recognize structurally distinct RNAs...
May 12, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28292241/microbial-pest-control-agents-are-they-a-specific-and-safe-tool-for-insect-pest-management
#16
Caroline Deshayes, Myriam Siegwart, David Pauron, Josy-Anne Froger, Bruno Lapied, Véronique Apaire-Marchais
Microorganisms (viruses, bacteria and fungi) or their bioactive agents can be used as active substances and therefore are referred as Microbial Pest Control Agents (MPCA). They are used as alternative strategies to chemical insecticides to counteract the development of resistances and to reduce adverse effects on both environment and human health. These natural entomopathogenic agents, which have specific modes of action, are generally considered safer as compared to conventional chemical insecticides. Baculoviruses are the only viruses being used as the safest biological control agents...
March 14, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/28282927/in-vivo-crystallization-of-three-domain-cry-toxins
#17
REVIEW
Rooma Adalat, Faiza Saleem, Neil Crickmore, Shagufta Naz, Abdul Rauf Shakoori
Bacillus thuringiensis (Bt) is the most successful, environmentally-friendly, and intensively studied microbial insecticide. The major characteristic of Bt is the production of proteinaceous crystals containing toxins with specific activity against many pests including dipteran, lepidopteran, and coleopteran insects, as well as nematodes, protozoa, flukes, and mites. These crystals allow large quantities of the protein toxins to remain stable in the environment until ingested by a susceptible host. It has been previously established that 135 kDa Cry proteins have a crystallization domain at their C-terminal end...
March 9, 2017: Toxins
https://www.readbyqxmd.com/read/28282873/crystal-structure-of-the-receptor-binding-domain-of-botulinum-neurotoxin-type-ha-also-known-as-type-fa-or-h
#18
Guorui Yao, Kwok-Ho Lam, Kay Perry, Jasmin Weisemann, Andreas Rummel, Rongsheng Jin
Botulinum neurotoxins (BoNTs), which have been exploited as cosmetics and muscle-disorder treatment medicines for decades, are well known for their extreme neurotoxicity to humans. They pose a potential bioterrorism threat because they cause botulism, a flaccid muscular paralysis-associated disease that requires immediate antitoxin treatment and intensive care over a long period of time. In addition to the existing seven established BoNT serotypes (BoNT/A-G), a new mosaic toxin type termed BoNT/HA (aka type FA or H) was reported recently...
March 8, 2017: Toxins
https://www.readbyqxmd.com/read/28243889/-1-h-13-c-15-n-backbone-assignment-of-the-human-heat-labile-enterotoxin-b-pentamer-and-chemical-shift-mapping-of-neolactotetraose-binding
#19
Daniel Hatlem, Julie E Heggelund, Daniel Burschowsky, Ute Krengel, Per E Kristiansen
The major virulence factor of enterotoxigenic Escherichia coli is the heat-labile enterotoxin (LT), an AB5 toxin closely related to the cholera toxin. LT consists of six subunits, the catalytically active A-subunit and five B-subunits arranged as a pentameric ring (LTB), which enable the toxin to bind to the epithelial cells in the intestinal lumen. LTB has two recognized binding sites; the primary binding site is responsible for anchoring the toxin to its main receptor, the GM1-ganglioside, while the secondary binding site recognizes blood group antigens...
February 27, 2017: Biomolecular NMR Assignments
https://www.readbyqxmd.com/read/28213222/development-of-a-qcm-d-biosensor-for-ochratoxin-a-detection-in-red-wine
#20
Aleksandra Karczmarczyk, Karsten Haupt, Karl-Heinz Feller
Ochratoxin A (OTA), a highly toxic compound, is one of the most widely spread mycotoxins that contaminates a large variety of agricultural commodities. Due to its presence in the food chain, it imposes a hazard on both human and animal health. Therefore, there is a need for precise, fast and simple methods for toxin quantification. Herein, a novel sensor based on a quartz crystal microbalance with dissipation monitoring (QCM-D) and antibodies for specific analyte recognition was developed for rapid and sensitive detection of OTA in red wine...
May 1, 2017: Talanta
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