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https://www.readbyqxmd.com/read/28089847/the-binding-orientation-of-epibatidine-at-%C3%AE-7-nach-receptors
#1
Andrew J Thompson, Simon Metzger, Martin Lochner, Marc-David Ruepp
Epibatidine is an alkaloid toxin that binds with high affinity to nicotinic and muscarinic acetylcholine receptors, and has been extensively used as a research tool. To examine binding interactions at the nicotinic receptor, it has been co-crystallised with the structural homologue acetylcholine binding protein (AChBP; PDB ID 2BYQ), and with an AChBP chimaera (3SQ6) that shares 64% sequence identity with the α7 nACh receptor. However, the binding orientations revealed by AChBP co-crystal structures may not precisely represent their receptor homologues and experimental evidence is needed to verify the ligand poses...
January 12, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28081148/characterization-of-multi-drug-resistant-enterococcus-faecalis-isolated-from-cephalic-recording-chambers-in-research-macaques-macaca-spp
#2
Stephanie E Woods, Mia T Lieberman, Francois Lebreton, Elise Trowel, César de la Fuente-Núñez, Joanne Dzink-Fox, Michael S Gilmore, James G Fox
Nonhuman primates are commonly used for cognitive neuroscience research and often surgically implanted with cephalic recording chambers for electrophysiological recording. Aerobic bacterial cultures from 25 macaques identified 72 bacterial isolates, including 15 Enterococcus faecalis isolates. The E. faecalis isolates displayed multi-drug resistant phenotypes, with resistance to ciprofloxacin, enrofloxacin, trimethoprim-sulfamethoxazole, tetracycline, chloramphenicol, bacitracin, and erythromycin, as well as high-level aminoglycoside resistance...
2017: PloS One
https://www.readbyqxmd.com/read/28067269/proteomic-analysis-of-cry2aa-binding-proteins-and-their-receptor-function-in-spodoptera-exigua
#3
Lin Qiu, Boyao Zhang, Lang Liu, Weihua Ma, Xiaoping Wang, Chaoliang Lei, Lizhen Chen
The bacterium Bacillus thuringiensis produces Crystal (Cry) proteins that are toxic to a diverse range of insects. Transgenic crops that produce Bt Cry proteins are grown worldwide because of their improved resistance to insect pests. Although Bt "pyramid" cotton that produces both Cry1A and Cry2A is predicted to be more resistant to several lepidopteran pests, including Spodoptera exigua, than plants that produce Cry1Ac alone, the mechanisms responsible for the toxicity of Cry2Aa in S. exigua are not well understood...
January 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28060413/molecularly-imprinted-polymer-chemosensor-for-selective-determination-of-an-n-nitroso-l-proline-food-toxin
#4
Patrycja Lach, Piyush Sindhu Sharma, Karolina Golebiewska, Maciej Cieplak, Francis D'Souza, Wlodzimierz Kutner
A molecularly imprinted polymer (MIP)-based chemosensor for the selective determination of a chosen toxin, N-nitroso-l-proline (Pro-NO), was devised and fabricated. By means of DFT, the structure of the pre-polymerization (functional monomer)-template complex was modeled. This complex was then potentiodynamically electropolymerized in the presence of cross-linking monomer to form a MIP-Pro-NO thin film. Next, the Pro-NO template was extracted from MIP-Pro-NO with 0.1 m NaOH. Piezoelectric microgravimetry (PM) on an electrochemical quartz crystal microbalance and electrochemical (differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS)) techniques were used to transduce binding of Pro-NO to molecular cavities of the MIP-Pro-NO...
November 7, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28056928/new-ligation-independent-cloning-vectors-for-expression-of-recombinant-proteins-with-a-self-cleaving-cpd-6xhis-tag
#5
Marco Biancucci, Jazel S Dolores, Jennifer Wong, Sarah Grimshaw, Wayne F Anderson, Karla J F Satchell, Keehwan Kwon
BACKGROUND: Recombinant protein purification is a crucial step for biochemistry and structural biology fields. Rapid robust purification methods utilize various peptide or protein tags fused to the target protein for affinity purification using corresponding matrices and to enhance solubility. However, affinity/solubility-tags often need to be removed in order to conduct functional and structural studies, adding complexities to purification protocols. RESULTS: In this work, the Vibrio cholerae MARTX toxin Cysteine Protease Domain (CPD) was inserted in a ligation-independent cloning (LIC) vector to create a C-terminal 6xHis-tagged inducible autoprocessing enzyme tag, called "the CPD-tag"...
January 5, 2017: BMC Biotechnology
https://www.readbyqxmd.com/read/28050633/biopolymer-microencapsulations-of-bacillus-thuringiensis-crystal-preparations-for-increased-stability-and-resistance-to-environmental-stress
#6
Xiaolin He, Zhongqin Sun, Kanglai He, Shuyuan Guo
Parasporal crystals synthesized by Bacillus thuringiensis (Bt) have been widely used as microbial pesticides because of their toxicity to the larval stages of specific insects. However, parasporal crystals can be damaged by environmental stresses, such as high temperature, ultraviolet radiation, and desiccation. To reduce environmental susceptibility of parasporal crystals and extend the duration of their activity, we developed a new type of protection by making microcapsules of crystals (MCs). The microcapsules were self-assembled by alternate deposition (layer by layer) of low-cost chitosan and sodium alginate (or sodium carboxymethyl cellulose) on the crystal surface...
January 3, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28034717/crystal-structure-of-a-phospholipase-a2-from-bothrops-asper-venom-insights-into-a-new-putative-myotoxic-cluster
#7
Guilherme H M Salvador, Juliana I Dos Santos, Bruno Lomonte, Marcos R M Fontes
Snake venoms from the Viperidae and Elapidae families often have several phospholipases A2 (PLA2s), which may display different functions despite having a similar structural scaffold. These proteins are considered an important target for the development of drugs against local myotoxic damage because they are not efficiently neutralized by conventional serum therapy. PLA2s from these venoms are generally divided into two classes: (i) catalytic PLA2s (or Asp49-PLA2s) and (ii) non-catalytic PLA2-like toxins (or Lys49-PLA2s)...
December 26, 2016: Biochimie
https://www.readbyqxmd.com/read/28007447/synthesis-of-some-ester-derivatives-of-4-demethoxyepipodophyllotoxin-2-chloro-4-demethoxyepipodophyllotoxin-as-insecticidal-agents-against-oriental-armyworm-mythimna-separata-walker
#8
Jiulin Huang, Ming Xu, Shaochen Li, Jiani He, Hui Xu
Podophyllotoxin is a naturally occurring non-alkaloid toxin isolated from the roots and rhizomes of Podophyllum peltatum and P. hexandrum. In continuation of our program aimed at the discovery and development of natural product-based insecticides, two series of ester derivatives of 4'-demethoxyepipodophyllotoxin/2'-chloro-4'-demethoxyepipodophyllotoxin were prepared. The structures of the target compounds were well characterized by 1H NMR, IR, optical rotation and mp. The precise three-dimensional structural information of 8j was further determined by single-crystal X-ray diffraction...
December 9, 2016: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28001053/low-dose-effects-nonmonotonic-responses-for-the-toxicity-of-a-bacillus-thuringiensis-biocide-to-daphnia-magna
#9
Anderson Abel de Souza Machado, Christiane Zarfl, Saskia Rehse, Werner Kloas
Currently, there is a trend toward an increasing use of biopesticides assumed to be environmentally friendly, such as Bacillus thuringiensis (Bt). Studies of the Bt toxicity to nontarget organisms have reported low effects at high exposure levels, which is interpreted as indicating negligible risk to nontarget organisms. We investigated the response of the nontarget organism Daphnia magna to waterborne DiPel ES, a globally used Bt formulation. Neonates and adults were exposed for 48 h to a wide range of concentrations, and immobilization and mortality were monitored...
January 18, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/27998932/toxin-inhibition-in-c-crescentus-vapbc1-is-mediated-by-a-flexible-pseudo-palindromic-protein-motif-and-modulated-by-dna-binding
#10
Kirstine L Bendtsen, Kehan Xu, Majbritt Luckmann, Kristoffer S Winther, Shiraz A Shah, Christian N S Pedersen, Ditlev E Brodersen
Expression of bacterial type II toxin-antitoxin (TA) systems is regulated at the transcriptional level through direct binding of the antitoxin to pseudo-palindromic sequences on operator DNA. In this context, the toxin functions as a co-repressor by stimulating DNA binding through direct interaction with the antitoxin. Here, we determine crystal structures of the complete 90 kDa heterooctameric VapBC1 complex from Caulobacter crescentus CB15 both in isolation and bound to its cognate DNA operator sequence at 1...
December 19, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27977897/the-membrane-localization-domains-of-two-distinct-bacterial-toxins-form-a-4-helix-bundle-in-solution
#11
Grant S Hisao, Michael C Brothers, Mengfei Ho, Brenda A Wilson, Chad M Rienstra
Membrane localization domain (MLD) was first proposed for a 4-helix-bundle motif in the crystal structure of the C1 domain of Pasteurella multocida toxin (PMT). This structure motif is also found in the crystal structures of several clostridial glycosylating toxins (TcdA, TcdB, TcsL, and TcnA). The Ras/Rap1-specific endopeptidase (RRSP) module of the multifunctional autoprocessing repeats-in-toxins (MARTX) toxin produced by Vibrio vulnificus has sequence homology to the C1-C2 domains of PMT, including a putative MLD...
December 15, 2016: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/27918112/validation-of-adam10-metalloprotease-as-a-bacillus-thuringiensis-cry3aa-toxin-functional-receptor-in-colorado-potato-beetle-leptinotarsa-decemlineata
#12
V M Ruiz-Arroyo, I García-Robles, C Ochoa-Campuzano, G A Goig, E Zaitseva, G Baaken, A C Martínez-Ramírez, C Rausell, M D Real
Bacillus thuringiensis parasporal crystal proteins (Cry proteins) are insecticidal pore-forming toxins that bind to specific receptor molecules on the brush border membrane of susceptible insect midgut cells to exert their toxic action. In the Colorado potato beetle (CPB), a coleopteran pest, we previously proposed that interaction of Cry3Aa toxin with a CPB ADAM10 metalloprotease is an essential part of the mode of action of this toxin. Here, we annotated the gene sequence encoding an ADAM10 metalloprotease protein (CPB-ADAM10) in the CPB genome sequencing project, and using RNA interference gene silencing we demonstrated that CPB-ADAM10 is a Cry3Aa toxin functional receptor in CPB...
December 5, 2016: Insect Molecular Biology
https://www.readbyqxmd.com/read/27917833/crystal-structure-of-the-toxin-msmeg_6760-the-structural-homolog-of-mycobacterium-tuberculosis-rv2035-a-novel-type-ii-toxin-involved-in-the-hypoxic-response
#13
R Alexandra Bajaj, Mark A Arbing, Annie Shin, Duilio Cascio, Linda Miallau
The structure of Msmeg_6760, a protein of unknown function, has been determined. Biochemical and bioinformatics analyses determined that Msmeg_6760 interacts with a protein encoded in the same operon, Msmeg_6762, and predicted that the operon is a toxin-antitoxin (TA) system. Structural comparison of Msmeg_6760 with proteins of known function suggests that Msmeg_6760 binds a hydrophobic ligand in a buried cavity lined by large hydrophobic residues. Access to this cavity could be controlled by a gate-latch mechanism...
December 1, 2016: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/27903650/structural-analysis-of-single-domain-antibodies-bound-to-a-second-neutralizing-hot-spot-on-ricin-toxin-s-enzymatic-subunit
#14
Michael J Rudolph, David J Vance, Michael S Cassidy, Yinghui Rong, Nicholas J Mantis
Ricin toxin is a heterodimer consisting of RTA, a ribosome-inactivating protein, and RTB, a lectin that facilitates receptor-mediated uptake into mammalian cells. In previous studies, we demonstrated that toxin-neutralizing antibodies target four spatially distinct hotspots on RTA, which we refer to as epitope Clusters I-IV. In this report we identified and characterized three single domain camelid antibodies (VHH) against Cluster II. One of these VHHs, V5E1, ranks as one of the most potent ricin-neutralizing antibodies described to date...
November 30, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27847174/protective-efficacy-of-a-novel-alpha-hemolysin-subunit-vaccine-at62-against-staphylococcus-aureus-skin-and-soft-tissue-infections
#15
Rajan P Adhikari, Christopher D Thompson, M Javad Aman, Jean C Lee
Alpha hemolysin (Hla) is a pore-forming toxin produced by most Staphylococcus aureus isolates. Hla is reported to play a key role in the pathogenesis of staphylococcal infections, such as skin and soft tissue infection, pneumonia, and lethal peritonitis. This study makes use of a novel recombinant subunit vaccine candidate (AT62) that was rationally designed based on the Hla heptameric crystal structure. AT62 comprises a critical structural domain at the N terminus of Hla, and it has no inherent toxic properties...
December 7, 2016: Vaccine
https://www.readbyqxmd.com/read/27819327/structure-and-function-of-fs50-a-salivary-protein-from-the-flea-xenopsylla-cheopis-that-blocks-the-sodium-channel-nav1-5
#16
Xueqing Xu, Bei Zhang, Shilong Yang, Su An, José M C Ribeiro, John F Andersen
Naturally occurring toxins have been invaluable tools for the study of structural and functional relationships of voltage-gated sodium channels (VGSC). Few studies have been made of potential channel-modulating substances from blood-feeding arthropods. He we describe the characterization FS50, a salivary protein from the flea, Xenopsylla cheopis, that exhibits an inhibitory activity against the NaV1.5 channel with an IC50 of 1.58 μM. The pore-blocking mechanism of this toxin is evident from the kinetics of activation and inactivation suggesting that FS50 does not interfere with the voltage sensor of NaV1...
November 7, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27807200/molecular-determinants-of-bk-channel-functional-diversity-and-functioning
#17
REVIEW
Ramon Latorre, Karen Castillo, Willy Carrasquel-Ursulaez, Romina V Sepulveda, Fernando Gonzalez-Nilo, Carlos Gonzalez, Osvaldo Alvarez
Large-conductance Ca(2+)- and voltage-activated K(+) (BK) channels play many physiological roles ranging from the maintenance of smooth muscle tone to hearing and neurosecretion. BK channels are tetramers in which the pore-forming α subunit is coded by a single gene (Slowpoke, KCNMA1). In this review, we first highlight the physiological importance of this ubiquitous channel, emphasizing the role that BK channels play in different channelopathies. We next discuss the modular nature of BK channel-forming protein, in which the different modules (the voltage sensor and the Ca(2+) binding sites) communicate with the pore gates allosterically...
January 2017: Physiological Reviews
https://www.readbyqxmd.com/read/27783504/the-remarkable-character-of-porphobilinogen-synthase
#18
Eileen K Jaffe
Porphobilinogen synthase (PBGS), also known as 5-aminolevulinate dehydratase, is an essential enzyme in the biosynthesis of all tetrapyrroles, which function in respiration, photosynthesis, and methanogenesis. Throughout evolution, PBGS adapted to a diversity of cellular niches and evolved to use an unusual variety of metal ions both for catalytic function and to control protein multimerization. With regard to the active site, some PBGSs require Zn(2+); a subset of those, including human PBGS, contain a constellation of cysteine residues that acts as a sink for the environmental toxin Pb(2+)...
November 15, 2016: Accounts of Chemical Research
https://www.readbyqxmd.com/read/27774510/robotic-qm-mm-driven-maturation-of-antibody-combining-sites
#19
Ivan V Smirnov, Andrey V Golovin, Spyros D Chatziefthimiou, Anastasiya V Stepanova, Yingjie Peng, Olga I Zolotareva, Alexey A Belogurov, Inna N Kurkova, Natalie A Ponomarenko, Matthias Wilmanns, G Michael Blackburn, Alexander G Gabibov, Richard A Lerner
In vitro selection of antibodies from large repertoires of immunoglobulin (Ig) combining sites using combinatorial libraries is a powerful tool, with great potential for generating in vivo scavengers for toxins. However, addition of a maturation function is necessary to enable these selected antibodies to more closely mimic the full mammalian immune response. We approached this goal using quantum mechanics/molecular mechanics (QM/MM) calculations to achieve maturation in silico. We preselected A17, an Ig template, from a naïve library for its ability to disarm a toxic pesticide related to organophosphorus nerve agents...
October 2016: Science Advances
https://www.readbyqxmd.com/read/27769815/parasporins-1-and-2-their-structure-and-activity
#20
Toshihiko Akiba, Shiro Okumura
Parasporins are novel protein toxins preferentially cytotoxic against human cancer cells. They are obtained from parasporal inclusions of Bacillus thuringiensis and, accordingly, are considered congeners of the insecticidal Cry toxins. Two types of parasporins have been identified: the three-domain Cry toxin type and the β-pore-forming-toxin (β-PFT) type. Crystal structures of representative members of the two types, PS1Aa1 and PS2Aa1, have been determined and compared with those of well-studied toxins. PS1Aa1 has a typical architecture characteristic of the three-domain insecticidal Cry toxins, though it is cleaved into two polypeptides...
October 18, 2016: Journal of Invertebrate Pathology
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