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Cryo electron microscopy

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https://www.readbyqxmd.com/read/29779042/combining-theoretical-and-experimental-data-to-decipher-cftr-3d-structures-and-functions
#1
Brice Hoffmann, Ahmad Elbahnsi, Pierre Lehn, Jean-Luc Décout, Fabio Pietrucci, Jean-Paul Mornon, Isabelle Callebaut
Cryo-electron microscopy (cryo-EM) has recently provided invaluable experimental data about the full-length cystic fibrosis transmembrane conductance regulator (CFTR) 3D structure. However, this experimental information deals with inactive states of the channel, either in an apo, quiescent conformation, in which nucleotide-binding domains (NBDs) are widely separated or in an ATP-bound, yet closed conformation. Here, we show that 3D structure models of the open and closed forms of the channel, now further supported by metadynamics simulations and by comparison with the cryo-EM data, could be used to gain some insights into critical features of the conformational transition toward active CFTR forms...
May 19, 2018: Cellular and Molecular Life Sciences: CMLS
https://www.readbyqxmd.com/read/29775653/atomic-structure-of-a-rationally-engineered-gene-delivery-vector-aav2-5
#2
Matthew Burg, Claire Rosebrough, Lauren M Drouin, Antonette Bennett, Mario Mietzsch, Paul Chipman, Robert McKenna, Duncan Sousa, Mark Potter, Barry Byrne, R Jude Samulski, Mavis Agbandje-McKenna
AAV2.5 represents the first structure-guided in-silico designed Adeno-associated virus (AAV) gene delivery vector. This engineered vector combined the receptor attachment properties of AAV serotype 2 (AAV2) with the muscle tropic properties of AAV1, and exhibited an antibody escape phenotype because of a modified antigenic epitope. To confirm the design, the structure of the vector was determined to a resolution of 2.78 Å using cryo-electron microscopy and image reconstruction. The structure of the major viral protein (VP), VP3, was ordered from residue 219 to 736, as reported for other AAV structures, and the five AAV2...
May 15, 2018: Journal of Structural Biology
https://www.readbyqxmd.com/read/29771342/recent-progress-in-structural-biology-lessons-from-our-research-history
#3
Ryo Nitta, Tsuyoshi Imasaki, Eriko Nitta
The recent 'resolution revolution' in structural analyses of cryo-electron microscopy (cryo-EM) has drastically changed the research strategy for structural biology. In addition to X-ray crystallography and nuclear magnetic resonance spectroscopy, cryo-EM has achieved the structural analysis of biological molecules at near-atomic resolution, resulting in the Nobel Prize in Chemistry 2017. The effect of this revolution has spread within the biology and medical science fields affecting everything from basic research to pharmaceutical development by visualizing atomic structure...
May 16, 2018: Microscopy
https://www.readbyqxmd.com/read/29769723/structure-of-a-volume-regulated-anion-channel-of-the-lrrc8-family
#4
Dawid Deneka, Marta Sawicka, Andy K M Lam, Cristina Paulino, Raimund Dutzler
Volume-regulated anion channels are activated in response to hypotonic stress. These channels are composed of closely related paralogues of the leucine-rich repeat-containing protein 8 (LRRC8) family that co-assemble to form hexameric complexes. Here, using cryo-electron microscopy and X-ray crystallography, we determine the structure of a homomeric channel of the obligatory subunit LRRC8A. This protein conducts ions and has properties in common with endogenous heteromeric channels. Its modular structure consists of a transmembrane pore domain followed by a cytoplasmic leucine-rich repeat domain...
May 16, 2018: Nature
https://www.readbyqxmd.com/read/29769334/reovirus-nonstructural-protein-%C3%AF-ns-acts-as-an-rna-stability-factor-promoting-viral-genome-replication
#5
Paula F Zamora, Liya Hu, Jonathan J Knowlton, Roni M Lahr, Rodolfo A Moreno, Andrea J Berman, B V Venkataram Prasad, Terence S Dermody
Viral nonstructural proteins, which are not packaged into virions, are essential for replication of most viruses. Reovirus, a nonenveloped, double-stranded RNA (dsRNA) virus, encodes three nonstructural proteins that are required for viral replication and dissemination in the host. Reovirus nonstructural protein σNS is a single-stranded RNA (ssRNA)-binding protein that must be expressed in infected cells for production of viral progeny. However, activities of σNS during individual steps of the reovirus replication cycle are poorly understood...
May 16, 2018: Journal of Virology
https://www.readbyqxmd.com/read/29767998/rapid-on-chip-assembly-of-niosomes-batch-versus-continuous-flow-reactors
#6
Sara Garcia-Salinas, Erico Himawan, Gracia Mendoza, Manuel Arruebo, Victor Sebastian Cabeza
The large-scale continuous production of niosomes remains challenging. The inherent drawbacks of batch processes such as large particle polydispersity and reduced batch-to-batch reproducibility are here overcome by using commercially available microfluidic reactors. Compared to the traditional batch-based film hydration method, herein, we demonstrate that it is possible to carry out the homogeneous, large-scale (up to 120mg/min) production of niosomes using two different synthesis techniques (the thin film hydration method and the emulsification technique)...
May 16, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29763607/biomedical-applications-of-lumazine-synthase
#7
Yangjie Wei, Prashant Kumar, Newton Wahome, Nicholas J Mantis, C Russell Middaugh
Lumazine synthase (LS) is a family of enzyme involved in the penultimate step in the biosynthesis of riboflavin. Its enzymatic mechanism has been well defined and many LS structures have been solved using x-ray crystallography or cryo-electron microscopy. LS is composed of homo-oligomers, which vary in size and subunit number, including pentamers, decamers, and icosahedral sixty-mers, depending on its species of origin. Research on LS has expanded beyond the initial focus on its enzymatic function to properties related to its oligomeric structure and exceptional conformational stability...
May 12, 2018: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29758539/bulk-and-dispersed-aqueous-behaviour-of-an-endogenous-lipid-selachyl-alcohol-effect-of-tween-80-and-pluronic-f127-on-nanostructure
#8
Mohammad Younus, Adrian Hawley, Ben J Boyd, Shakila B Rizwan
Tween 80 has been reported to provide a means of targeting drug nanocarriers to the blood- brain barrier. This study investigated the influence of addition of Tween 80 on the formation of different bulk and dispersed lyotropic liquid crystalline phases in selachyl alcohol-based systems. The effect of increasing concentrations of Tween 80 and Pluronic F127 (as a control) (0-25% w/w relative to SA) on the bulk phase behaviour and dispersions of selachyl alcohol (SA) were investigated using small angle X-ray scattering, dynamic light scattering, and cryogenic transmission electron microscopy...
May 7, 2018: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29754826/atomic-resolution-cryo-em-structure-of-%C3%AE-galactosidase
#9
Alberto Bartesaghi, Cecilia Aguerrebere, Veronica Falconieri, Soojay Banerjee, Lesley A Earl, Xing Zhu, Nikolaus Grigorieff, Jacqueline L S Milne, Guillermo Sapiro, Xiongwu Wu, Sriram Subramaniam
The advent of direct electron detectors has enabled the routine use of single-particle cryo-electron microscopy (EM) approaches to determine structures of a variety of protein complexes at near-atomic resolution. Here, we report the development of methods to account for local variations in defocus and beam-induced drift, and the implementation of a data-driven dose compensation scheme that significantly improves the extraction of high-resolution information recorded during exposure of the specimen to the electron beam...
April 30, 2018: Structure
https://www.readbyqxmd.com/read/29754486/nanoparticle-wettability-influences-nanoparticle-phospholipid-interactions
#10
Nagarjun Konduru, Flavia Damiani, Svetla Stoilova-McPhie, Jason Tresback, Georgios Pyrgiotakis, Thomas C Donaghey, Philip Demokritou, Joseph Brain, Ramon M Molina
We explored the influence of nanoparticle (NP) surface charge and hydrophobicity on nanoparticle-biomolecule interactions by measuring the composition of adsorbed phospholipids on four NPs, namely positively charged CeO2 and ZnO, and negatively charged BaSO4 and silica-coated CeO2 after exposure to bronchoalveolar lavage fluid (BALf) obtained from rats, and to a mixture of neutral dipalmitoyl phosphatidylcholine (DPPC) and negatively charged dipalmitoyl phosphatidic acid (DPPA). The resulting NP-lipid interactions were examined by cryogenic transmission electron microscopy (cryo-TEM) and by atomic force microscopy (AFM)...
May 12, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29752414/ligand-binding-and-activation-properties-of-the-purified-bacterial-cyclic-nucleotide-gated-channel-sthk
#11
Philipp A M Schmidpeter, Xiaolong Gao, Vikrant Uphadyay, Jan Rheinberger, Crina M Nimigean
Cyclic nucleotide-modulated ion channels play several essential physiological roles. They are involved in signal transduction in photoreceptors and olfactory sensory neurons as well as pacemaking activity in the heart and brain. Investigations of the molecular mechanism of their actions, including structural and electrophysiological characterization, are restricted by the availability of stable, purified protein obtained from accessible systems. Here, we establish that SthK, a cyclic nucleotide-gated (CNG) channel from Spirochaeta thermophila , is an excellent model for investigating the gating of eukaryotic CNG channels at the molecular level...
May 11, 2018: Journal of General Physiology
https://www.readbyqxmd.com/read/29748979/quantitative-cryo-scanning-transmission-electron-microscopy-of-biological-materials
#12
REVIEW
Michael Elbaum
Electron tomography provides a detailed view into the 3D structure of biological cells and tissues. Physical fixation by vitrification of the aqueous medium provides the most faithful preservation of biological specimens in the native, fully hydrated state. Cryo-microscopy is challenging, however, because of the sensitivity to electron irradiation and due to the weak electron scattering of organic material. Tomography is even more challenging because of the dependence on multiple exposures of the same area...
May 11, 2018: Advanced Materials
https://www.readbyqxmd.com/read/29748322/near-atomic-model-of-microtubule-tau-interactions
#13
Elizabeth H Kellogg, Nisreen M A Hejab, Simon Poepsel, Kenneth H Downing, Frank DiMaio, Eva Nogales
Tau is a developmentally regulated axonal protein that stabilizes and bundles microtubules (MTs). Its hyperphosphorylation is thought to cause detachment from MTs and subsequent aggregation into fibrils implicated in Alzheimer's disease. It is unclear which tau residues are crucial for tau-MT interactions, where tau binds on MTs, and how it stabilizes them. We used cryo-electron microscopy to visualize different tau constructs on MTs, and computational approaches to generate atomic models of tau-tubulin interactions...
May 10, 2018: Science
https://www.readbyqxmd.com/read/29748256/structure-mechanism-and-regulation-of-the-chloroplast-atp-synthase
#14
Alexander Hahn, Janet Vonck, Deryck J Mills, Thomas Meier, Werner Kühlbrandt
The chloroplast adenosine triphosphate (ATP) synthase uses the electrochemical proton gradient generated by photosynthesis to produce ATP, the energy currency of all cells. Protons conducted through the membrane-embedded Fo motor drive ATP synthesis in the F1 head by rotary catalysis. We determined the high-resolution structure of the complete cF1 Fo complex by cryo-electron microscopy, resolving side chains of all 26 protein subunits, the five nucleotides in the F1 head, and the proton pathway to and from the rotor ring...
May 11, 2018: Science
https://www.readbyqxmd.com/read/29745897/structure-of-a-trpm2-channel-in-complex-with-ca-2-explains-unique-gating-regulation
#15
Zhe Zhang, Balázs Tóth, Andras Szollosi, Jue Chen, László Csanády
Transient Receptor Potential Melastatin 2 (TRPM2) is a Ca2+ -permeable cation channel required for immune cell activation, insulin secretion, and body heat control. TRPM2 is activated by cytosolic Ca2+ , phosphatidyl-inositol-4,5-bisphosphate and ADP ribose. Here we present the ~3Å resolution electron cryo-microscopy structure of TRPM2 from Nematostella vectensis , 63% similar in sequence to human TRPM2, in the Ca2+ -bound closed state. Compared to other TRPM channels, TRPM2 exhibits unique structural features that correlate with its function...
May 10, 2018: ELife
https://www.readbyqxmd.com/read/29745668/temperature-induced-self-assembly-of-the-group-b-streptococcus-gbs-fusion-antigen-gbs-nn
#16
Fabrice Rose, Silke Roovers, Mathias Fanø, Stine Harloff-Helleberg, Jacob Judas Kain Kirkensgaard, Kim Hejnaes, Per Fischer, Camilla Foged
Group B streptococcus (GBS) is a leading cause of serious bacterial neonatal infections worldwide, which provides an unmet medical need for a globally effective vaccine. The recombinant GBS fusion antigen GBS-NN contains the N-terminal regions of the GBS Rib and Alpha C proteins. It shows promising immunogenicity eliciting protective immunity in mice and encouraging results in early human clinical trials. Understanding the physical stability of GBS-NN containing conformational B-cell epitopes is crucial to ensure optimal vaccine stability, efficacy and safety...
May 10, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29738465/unconventional-imaging-methods-to-capture-transient-structures-during-actomyosin-interaction
#17
REVIEW
Eisaku Katayama, Noriyuki Kodera
Half a century has passed since the cross-bridge structure was recognized as the molecular machine that generates muscle tension. Despite various approaches by a number of scientists, information on the structural changes in the myosin heads, particularly its transient configurations, remains scant even now, in part because of their small size and rapid stochastic movements during the power stroke. Though progress in cryo-electron microscopy is eagerly awaited as the ultimate means to elucidate structural details, the introduction of some unconventional methods that provide high-contrast raw images of the target protein assemblies is quite useful, if available, to break the current impasse...
May 8, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29738229/arginine-containing-surfactant-like-peptides-interaction-with-lipid-membranes-and-antimicrobial-activity
#18
Valeria Castelletto, Ruth H Barnes, Kimon-Andreas Karatzas, Charlotte J C Edwards-Gayle, Francesca Greco, Ian W Hamley, Robert Rambo, Jani Seitsonen, Janne Ruokolainen
The activity of antimicrobial peptides stems from their interaction with bacterial membranes, which are disrupted according to a number of proposed mechanisms. Here, we investigate the interaction of a model antimicrobial peptide that contains a single arginine residue with vesicles containing model lipid membranes. The surfactant-like peptide Ala6-Arg (A6R) is studied in the form where both termini are capped (CONH-A6R-NH2, capA6R) or uncapped (NH2-A6R-OH, A6R). Lipid membranes are selected to correspond to model anionic membranes (POPE/POPG) resembling those in bacteria or model zwitterionic membranes (POPC/DOPC) similar to those found in mammalian cells...
May 8, 2018: Biomacromolecules
https://www.readbyqxmd.com/read/29734684/comparing-the-folds-of-prions-and-other-pathogenic-amyloids
#19
REVIEW
José Miguel Flores-Fernández, Vineet Rathod, Holger Wille
Pathogenic amyloids are the main feature of several neurodegenerative disorders, such as Creutzfeldt⁻Jakob disease, Alzheimer’s disease, and Parkinson’s disease. High resolution structures of tau paired helical filaments (PHFs), amyloid-β(1-42) (Aβ(1-42)) fibrils, and α-synuclein fibrils were recently reported using cryo-electron microscopy. A high-resolution structure for the infectious prion protein, PrPSc , is not yet available due to its insolubility and its propensity to aggregate, but cryo-electron microscopy, X-ray fiber diffraction, and other approaches have defined the overall architecture of PrPSc as a 4-rung β-solenoid...
May 4, 2018: Pathogens
https://www.readbyqxmd.com/read/29728606/structure-and-mechanism-of-the-two-component-%C3%AE-helical-pore-forming-toxin-yaxab
#20
Bastian Bräuning, Eva Bertosin, Florian Praetorius, Christian Ihling, Alexandra Schatt, Agnes Adler, Klaus Richter, Andrea Sinz, Hendrik Dietz, Michael Groll
Pore-forming toxins (PFT) are virulence factors that transform from soluble to membrane-bound states. The Yersinia YaxAB system represents a family of binary α-PFTs with orthologues in human, insect, and plant pathogens, with unknown structures. YaxAB was shown to be cytotoxic and likely involved in pathogenesis, though the molecular basis for its two-component lytic mechanism remains elusive. Here, we present crystal structures of YaxA and YaxB, together with a cryo-electron microscopy map of the YaxAB complex...
May 4, 2018: Nature Communications
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