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https://www.readbyqxmd.com/read/28102751/extracellular-vesicles-from-activated-platelets-a-semiquantitative-cryo-electron-microscopy-and-immuno-gold-labeling-study
#1
Alain R Brisson, Sisareuth Tan, Romain Linares, Céline Gounou, Nicolas Arraud
Cells release membrane vesicles in their surrounding medium either constitutively or in response to activating signals. Two main types of extracellular vesicles (EVs) are commonly distinguished based on their mechanism of formation, membrane composition and size. According to the current model, EVs shed from the plasma membrane, often called microvesicles, expose phosphatidylserine (PS) and range in size from 100 nm to 1 µm, while EVs originating from endosomal multi-vesicular bodies, called exosomes, contain tetraspanin proteins, including CD63, and range in size from 50 to 100 nm...
January 19, 2017: Platelets
https://www.readbyqxmd.com/read/28102121/inflammasomes-in-myeloid-cells-warriors-within
#2
Sushmita Jha, W June Brickey, Jenny Pan-Yun Ting
The inflammasome is a large multimeric protein complex comprising an effector protein that demonstrates specificity for a variety of activators or ligands; an adaptor molecule; and procaspase-1, which is converted to caspase-1 upon inflammasome activation. Inflammasomes are expressed primarily by myeloid cells and are located within the cell. The macromolecular inflammasome structure can be visualized by cryo-electron microscopy. This complex has been found to play a role in a variety of disease models in mice, and several have been genetically linked to human diseases...
January 2017: Microbiology Spectrum
https://www.readbyqxmd.com/read/28100648/multi-scale-structural-analysis-of-plant-er-pm-contact-sites
#3
Heather E McFarlane, Eun Kyoung Lee, Laura S van Bezouwen, Bradford Ross, Abel Rosado, A Lacey Samuels
Membrane contact sites (MCS) are recognized across eukaryotic systems as important nanostructures. Endoplasmic reticulum (ER)-plasma membrane (PM) contact sites (EPCS) are involved in excitation-contraction coupling, signalling, and plant responses to stress. In this report, we perform a multi-scale structural analysis of Arabidopsis EPCS that combine live cell imaging, quantitative transmission electron microscopy (TEM), and electron tomography over a developmental gradient. To place EPCS in the context of the entire cortical ER, we examined GFP-HDEL in living cells over a developmental gradient, then SYT1-GFP was used as a specific marker of EPCS...
January 18, 2017: Plant & Cell Physiology
https://www.readbyqxmd.com/read/28099415/structure-of-a-eukaryotic-cyclic-nucleotide-gated-channel
#4
Minghui Li, Xiaoyuan Zhou, Shu Wang, Ioannis Michailidis, Ye Gong, Deyuan Su, Huan Li, Xueming Li, Jian Yang
Cyclic-nucleotide-gated channels are essential for vision and olfaction. They belong to the voltage-gated ion channel superfamily but their activities are controlled by intracellular cyclic nucleotides instead of transmembrane voltage. Here we report a 3.5-Å-resolution single-particle electron cryo-microscopy structure of a cyclic-nucleotide-gated channel from Caenorhabditis elegans in the cyclic guanosine monophosphate (cGMP)-bound open state. The channel has an unusual voltage-sensor-like domain, accounting for its deficient voltage dependence...
January 18, 2017: Nature
https://www.readbyqxmd.com/read/28098315/a-ph-responsive-wormlike-micellar-system-of-a-noncovalent-interaction-based-surfactant-with-a-tunable-molecular-structure
#5
Wanli Kang, Pengxiang Wang, Haiming Fan, Hongbin Yang, Caili Dai, Xia Yin, Yilu Zhao, Shujun Guo
Responsive wormlike micelles are very useful in a number of applications, whereas it is still challenging to create dramatic viscosity changes in wormlike micellar systems. Here we developed a pH-responsive wormlike micellar system based on a noncovalent constructed surfactant, which is formed by the complexation of N-erucamidopropyl-N,N-dimethylamine (UC22AMPM) and citric acid at the molar ratio of 3 : 1 (EACA). The phase behavior, aggregate microstructure and viscoelasticity of EACA solutions were investigated by macroscopic appearance observation, rheological and cryo-TEM measurements...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28097914/nanostructured-lipid-carriers-nlc-for-the-delivery-of-natural-molecules-with-antimicrobial-activity-production-characterization-and-in-vitro-studies
#6
Rita Cortesi, Giuseppe Valacchi, Ximena M Muresan, Markus Drechsler, Catia Contado, Elisabetta Esposito, Alessandro Grandini, Alessandra Guerrini, Giuseppe Forlani, Gianni Sacchetti
This study describes the preparation, characterization and in vitro activity of nanostructured lipid carriers (NLC) encapsulating natural molecules with antimicrobial activity, such as plumbagin, hydroquinon, eugenol, alpha-asarone and alpha-tocopherol. NLC were prepared by melt and ultrasonication method, characterized by Cryo-TEM for morphology and SdFFF for dimensional distribution and active encapsulation yields. In vitro tests were conducted on bacteria, fungi and human cell cultures. In vitro tests demonstrated that plumbagin is strongly toxic towards F...
January 18, 2017: Journal of Microencapsulation
https://www.readbyqxmd.com/read/28096349/structure-of-eukaryotic-cmg-helicase-at-a-replication-fork-and-implications-to-replisome-architecture-and-origin-initiation
#7
Roxana Georgescu, Zuanning Yuan, Lin Bai, Ruda de Luna Almeida Santos, Jingchuan Sun, Dan Zhang, Olga Yurieva, Huilin Li, Michael E O'Donnell
The eukaryotic CMG (Cdc45, Mcm2-7, GINS) helicase consists of the Mcm2-7 hexameric ring along with five accessory factors. The Mcm2-7 heterohexamer, like other hexameric helicases, is shaped like a ring with two tiers, an N-tier ring composed of the N-terminal domains, and a C-tier of C-terminal domains; the C-tier contains the motor. In principle, either tier could translocate ahead of the other during movement on DNA. We have used cryo-EM single-particle 3D reconstruction to solve the structure of CMG in complex with a DNA fork...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28094536/the-novel-induction-of-retinal-ganglion-cell-apoptosis-in-porcine-organ-culture-by-nmda-an-opportunity-for-the-replacement-of-animals-in-experiments
#8
Sandra Kuehn, Jose Hurst, Adelina Jashari, Kathrin Ahrens, Teresa Tsai, Ilan M Wunderlich, H Burkhard Dick, Stephanie C Joachim, Sven Schnichels
Some of the advantages of retina organ culture models include their efficient and easy handling and the ability to standardise relevant parameters. Additionally, when porcine eyes are obtained from the food industry, no animals are killed solely for research purposes. To induce retinal degeneration, a commonly used toxic substance, N-methyl-D-aspartate (NMDA), was applied to the cultures. To this end, organotypic cultures of porcine retinas were cultured and treated with different doses of NMDA (0 [control], 50, 100 and 200μM) on day 2 for 48 hours...
December 2016: Alternatives to Laboratory Animals: ATLA
https://www.readbyqxmd.com/read/28094514/structural-model-of-the-tubular-assembly-of-the-rous-sarcoma-virus-capsid-protein
#9
Jaekyun Jeon, Xin Qiao, Ivan Hung, Alok K Mitra, Ambroise Desfosses, Daniel Huang, Peter L Gor'kov, Rebecca C Craven, Richard L Kingston, Zhehong Gan, Fangqiang Zhu, Bo Chen
The orthoretroviral capsid protein (CA) assembles into polymorphic capsids, whose architecture, assembly and stability are still being investigated. The N-terminal and C-terminal domains of CA (NTD and CTD, respectively) engage in both homotypic and heterotypic interactions to create the capsid. Hexameric turrets formed by the NTD decorate the majority of the capsid surface. We report nearly-complete solid-state NMR (ssNMR) resonance assignments of Rous sarcoma virus (RSV) CA, assembled into hexamer tubes that mimic the authentic capsid...
January 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28094405/controlled-and-tunable-design-of-polymer-interface-for-immobilization-of-enzymes-does-curvature-matter
#10
Claudia Marschelke, Ivan Raguzin, Anke Matura, Andreas Fery, Alla Synytska
Control and tuning of surface properties is indispensable for the programmed and rational design of materials. Particularly, polymeric brush-modified colloids can be used as carrier materials for enzyme immobilization. Although it is of prime importance to control the brush architecture, there is still a lack of systematic investigations concerning the impact of grafting density on the properties of the designed interface, as well as on the immobilization of biomolecules. In this work, we investigate the surface properties of polymer brushes with different grafting densities prepared using a "grafting from" approach on flat and on colloidal particle substrates by varying the density of initiator groups...
January 17, 2017: Soft Matter
https://www.readbyqxmd.com/read/28093324/synthesis-characterization-and-in-vitro-antitumor-activity-of-the-polyethylene-glycol-350-and-1000-succinate-derivatives-of-the-tocopherol-and-tocotrienol-isomers-of-vitamin-e
#11
Ahmed Abu-Fayyad, Sami Nazzal
Vitamin E refers to a group of saturated tocopherol (T) isomers and the biologically more active unsaturated tocotrienol (T3) isomers. PEGylated α-tocopherol, commercially known as Vitamin E TPGS, has been used as an emulsifier and therapeutic agent for children with vitamin E deficiency. Limited information, however, is available about the PEG conjugates of the tocotrienol isomers of vitamin E. The current work was therefore undertaken to synthesize and characterize the water soluble polyethylene glycol (PEG 350 and 1000) derivatives of T and T3...
January 13, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28093199/effect-of-different-cryo-devices-on-in-vitro-maturation-and-development-of-vitrified-warmed-immature-buffalo-oocytes
#12
Yelisetti Uma Mahesh, Henderson Rose Winnie Gibence, Sisinthy Shivaji, Brahmasani Sambasiva Rao
The aim of the study was to identify a cryo-device that would be best suited for the vitrification of buffalo immature cumulus-oocyte complexes (COCs) as judged by viability and meiotic competence of the vitrified-warmed oocytes and their development ability following in vitro fertilization (IVF). The expression of oocyte secreting factors and their receptors (GDF9, BMP15, BMPR2, TGFBR1) and apoptosis related genes (BCL2, BAX, P53, C-MYC) were compared in vitrified-warmed oocytes after in vitro maturation. COCs from the ovaries of slaughtered buffaloes were vitrified in a combination of dimethyl sulfoxide, ethylene glycol, and sucrose using either a conventional straw (CS), open pulled straw (OPS), cryoloop (CL), hemistraw (HS) or cryotop (CT)...
January 13, 2017: Cryobiology
https://www.readbyqxmd.com/read/28092368/molecular-insights-into-lipid-assisted-ca-2-regulation-of-the-trp-channel-polycystin-2
#13
Martin Wilkes, M Gregor Madej, Lydia Kreuter, Daniel Rhinow, Veronika Heinz, Silvia De Sanctis, Sabine Ruppel, Rebecca M Richter, Friederike Joos, Marina Grieben, Ashley C W Pike, Juha T Huiskonen, Elisabeth P Carpenter, Werner Kühlbrandt, Ralph Witzgall, Christine Ziegler
Polycystin-2 (PC2), a calcium-activated cation TRP channel, is involved in diverse Ca(2+) signaling pathways. Malfunctioning Ca(2+) regulation in PC2 causes autosomal-dominant polycystic kidney disease. Here we report two cryo-EM structures of distinct channel states of full-length human PC2 in complex with lipids and cations. The structures reveal conformational differences in the selectivity filter and in the large exoplasmic domain (TOP domain), which displays differing N-glycosylation. The more open structure has one cation bound below the selectivity filter (single-ion mode, PC2SI), whereas multiple cations are bound along the translocation pathway in the second structure (multi-ion mode, PC2MI)...
January 16, 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/28092267/cryo-em-structure-of-the-atp-sensitive-potassium-channel-illuminates-mechanisms-of-assembly-and-gating
#14
Gregory M Martin, Craig Yoshioka, Emily A Rex, Jonathan F Fay, Qing Xie, Matthew R Whorton, James Z Chen, Show-Ling Shyng
KATP channels are metabolic sensors that couple cell energetics to membrane excitability. In pancreatic β-cells, channels formed by SUR1 and Kir6.2 regulate insulin secretion and are the targets of antidiabetic sulfonylureas. Here, we used cryo-EM to elucidate structural basis of channel assembly and gating. The structure, determined in the presence of ATP and the sulfonylurea glibenclamide, at ~6Å resolution reveals a closed Kir6.2 tetrameric core with four peripheral SUR1s each anchored to a Kir6.2 by its N-terminal transmembrane domain (TMD0)...
January 16, 2017: ELife
https://www.readbyqxmd.com/read/28089452/co-folding-of-a-flif-flig-split-domain-forms-the-basis-of-the-ms-c-ring-interface-within-the-bacterial-flagellar-motor
#15
Michael J Lynch, Robert Levenson, Eun A Kim, Ria Sircar, David F Blair, Frederick W Dahlquist, Brian R Crane
The interface between the membrane (MS) and cytoplasmic (C) rings of the bacterial flagellar motor couples torque generation to rotation within the membrane. The structure of the C-terminal helices of the integral membrane protein FliF (FliFC) bound to the N terminal domain of the switch complex protein FliG (FliGN) reveals that FliGN folds around FliFC to produce a topology that closely resembles both the middle and C-terminal domains of FliG. The interface is consistent with solution-state nuclear magnetic resonance, small-angle X-ray scattering, in vivo interaction studies, and cellular motility assays...
December 31, 2016: Structure
https://www.readbyqxmd.com/read/28088669/micro-mechanical-properties-of-the-tendon-to-bone-attachment
#16
Alix C Deymier, Yiran An, John J Boyle, Andrea G Schwartz, Victor Birman, Guy M Genin, Stavros Thomopoulos, Asa H Barber
: The tendon-to-bone attachment (enthesis) is a complex hierarchical tissue that connects stiff bone to compliant tendon. The attachment site at the micrometer scale exhibits gradients in mineral content and collagen orientation, which likely act to minimize stress concentrations. The physiological micromechanics of the attachment thus define resultant performance, but difficulties in sample preparation and mechanical testing at this scale have restricted understanding of structure-mechanical function...
January 11, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28088125/computational-methods-for-analyzing-conformational-variability-of-macromolecular-complexes-from-cryo-electron-microscopy-images
#17
REVIEW
Slavica Jonić
Thanks to latest technical advances in cryo-electron microscopy (cryo-EM), structures of macromolecular complexes (viruses, ribosomes, etc.) are now often obtained at near-atomic resolution. Also, studies of conformational changes of complexes, in connection with their function, are gaining ground. Conformational variability analysis is usually done by classifying images in a number of discrete classes supposedly representing all conformational states present in the specimen. However, discrete classes cannot be meaningfully defined when the conformational change is continuous (the specimen contains a continuum of states instead of a few discrete states)...
January 11, 2017: Current Opinion in Structural Biology
https://www.readbyqxmd.com/read/28086931/the-release-and-trans-synaptic-transmission-of-tau-via-exosomes
#18
Yipeng Wang, Varun Balaji, Senthilvelrajan Kaniyappan, Lars Krüger, Stephan Irsen, Katharina Tepper, RamReddy Chandupatla, Walter Maetzler, Anja Schneider, Eckhard Mandelkow, Eva-Maria Mandelkow
BACKGROUND: Tau pathology in AD spreads in a hierarchical pattern, whereby it first appears in the entorhinal cortex, then spreads to the hippocampus and later to the surrounding areas. Based on this sequential appearance, AD can be classified into six stages ("Braak stages"). The mechanisms and agents underlying the progression of Tau pathology are a matter of debate. Emerging evidence indicates that the propagation of Tau pathology may be due to the transmission of Tau protein, but the underlying pathways and Tau species are not well understood...
January 13, 2017: Molecular Neurodegeneration
https://www.readbyqxmd.com/read/28080038/tracking-catalyst-redox-states-and-reaction-dynamics-in-ni-fe-oxyhydroxide-oxygen-evolution-reaction-oer-electrocatalysts-the-role-of-catalyst-support-and-electrolyte-ph
#19
Mikaela Goerlin, Jorge Ferreira de Araújo, Henrike Schmies, Denis Bernsmeier, Soeren Dresp, Manuel Gliech, Zenonas Jusys, Petko Chernev, Ralph Kraehnert, Holger Dau, Peter Strasser
Ni-Fe oxyhydroxides are the most active known electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolytes and are therefore of great scientific and technological importance in the context of electrochemical energy conversion. Here we uncover, investigate, and discuss previously unaddressed effects of conductive supports and the electrolyte pH on the Ni-Fe oxide catalyst redox behavior and catalytic OER activity, combining operando UV-vis spectro-electrochemistry, operando electrochemical mass spectrometry (DEMS), and in-situ cryo X-ray absorption spectroscopy (XAS)...
January 12, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28077875/structural-basis-of-co-translational-quality-control-by-arfa-and-rf2-bound-to-ribosome
#20
Fuxing Zeng, Yanbo Chen, Jonathan Remis, Mrinal Shekhar, James C Phillips, Emad Tajkhorshid, Hong Jin
Quality control mechanisms intervene appropriately when defective translation events occur, in order to preserve the integrity of protein synthesis. Rescue of ribosomes translating on messenger RNAs that lack stop codons is one of the co-translational quality control pathways. In many bacteria, ArfA recognizes stalled ribosomes and recruits the release factor RF2, which catalyses the termination of protein synthesis. Although an induced-fit mechanism of nonstop mRNA surveillance mediated by ArfA and RF2 has been reported, the molecular interaction between ArfA and RF2 in the ribosome that is responsible for the mechanism is unknown...
January 11, 2017: Nature
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