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https://www.readbyqxmd.com/read/29151266/crystal-structure-and-catalytic-characterization-of-the-dehydrogenase-reductase-sdr-family-member-4-dhrs4-from-caenorhabditis-elegans
#1
Michael Kisiela, Annette Faust, Bettina Ebert, Edmund Maser, Axel J Scheidig
The human dehydrogenase/reductase SDR family member 4 (DHRS4) is a tetrameric protein that is involved in the metabolism of several aromatic carbonyl compounds, steroids and bile acids. The only invertebrate DHRS4 that has been characterized to date is that from the model organism Caenorhabditis elegans. We have previously cloned and initially characterized this protein that was recently annotated as DHRS4_CAEEL in the UniProtKB database. Crystallization and X-ray diffraction studies of the full-length DHRS4_CAEEL protein in complex with diacetyl revealed its tetrameric structure and showed that two subunits are connected via an intermolecular disulfide bridge that is formed by N-terminal cysteine residues (Cys5) of each protein chain, which increases the enzymatic activity...
November 19, 2017: FEBS Journal
https://www.readbyqxmd.com/read/29151218/structures-of-dynamic-protein-complexes-hybrid-techniques-to-study-map-kinase-complexes-and-the-escrt-system
#2
Wolfgang Peti, Rebecca Page, Evzen Boura, Bartosz Różycki
The integration of complementary molecular methods (including X-ray crystallography, NMR spectroscopy, small angle X-ray/neutron scattering, and computational techniques) is frequently required to obtain a comprehensive understanding of dynamic macromolecular complexes. In particular, these techniques are critical for studying intrinsically disordered protein regions (IDRs) or intrinsically disordered proteins (IDPs) that are part of large protein:protein complexes. Here, we explain how to prepare IDP samples suitable for study using NMR spectroscopy, and describe a novel SAXS modeling method (ensemble refinement of SAXS; EROS) that integrates the results from complementary methods, including crystal structures and NMR chemical shift perturbations, among others, to accurately model SAXS data and describe ensemble structures of dynamic macromolecular complexes...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29150603/bacterially-derived-synthetic-mimetics-of-mammalian-oligomannose-prime-antibody-responses-that-neutralize-hiv-infectivity
#3
Ralph Pantophlet, Nino Trattnig, Sasha Murrell, Naiomi Lu, Dennis Chau, Caitlin Rempel, Ian A Wilson, Paul Kosma
Oligomannose-type glycans are among the major targets on the gp120 component of the HIV envelope protein (Env) for broadly neutralizing antibodies (bnAbs). However, attempts to elicit oligomannose-specific nAbs by immunizing with natural or synthetic oligomannose have so far not been successful, possibly due to B cell tolerance checkpoints. Here we design and synthesize oligomannose mimetics, based on the unique chemical structure of a recently identified bacterial lipooligosaccharide, to appear foreign to the immune system...
November 17, 2017: Nature Communications
https://www.readbyqxmd.com/read/29150515/loop-of-streptomyces-feruloyl-esterase-plays-an-important-role-in-its-activity-of-releasing-ferulic-acid-from-biomass
#4
Misugi Uraji, Haruka Tamura, Eiichi Mizohata, Jiro Arima, Kun Wan, Ken'ichi Ogawa, Tsuyoshi Inoue, Tadashi Hatanaka
Feruloyl esterases (FAEs) are key enzymes required for the production of ferulic acid from agricultural biomass. Previously, we identified and characterized R18, an FAE from Streptomyces cinnamoneus NBRC 12852, which showed no sequence similarity with the known FAEs. To determine the region involved in its catalytic activity, we constructed chimeric enzymes using R18 and its homolog (TH2-18) from S. cinnamoneus strain TH-2. Although R18 and TH2-18 showed 74% identity in their primary sequence, the recombinant proteins of these two FAEs (rR18 and rTH2-18) showed very different specific activities toward ethyl ferulate...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29149603/structural-basis-of-mitochondrial-transcription-initiation
#5
Hauke S Hillen, Yaroslav I Morozov, Azadeh Sarfallah, Dmitry Temiakov, Patrick Cramer
Transcription in human mitochondria is driven by a single-subunit, factor-dependent RNA polymerase (mtRNAP). Despite its critical role in both expression and replication of the mitochondrial genome, transcription initiation by mtRNAP remains poorly understood. Here, we report crystal structures of human mitochondrial transcription initiation complexes assembled on both light and heavy strand promoters. The structures reveal how transcription factors TFAM and TFB2M assist mtRNAP to achieve promoter-dependent initiation...
November 16, 2017: Cell
https://www.readbyqxmd.com/read/29149597/structural-basis-for-shelterin-bridge-assembly
#6
Jin-Kwang Kim, Jinqiang Liu, Xichan Hu, Clinton Yu, Kyle Roskamp, Banumathi Sankaran, Lan Huang, Elizabeth A Komives, Feng Qiao
Telomere elongation through telomerase enables chromosome survival during cellular proliferation. The conserved multifunctional shelterin complex associates with telomeres to coordinate multiple telomere activities, including telomere elongation by telomerase. Similar to the human shelterin, fission yeast shelterin is composed of telomeric sequence-specific double- and single-stranded DNA-binding proteins, Taz1 and Pot1, respectively, bridged by Rap1, Poz1, and Tpz1. Here, we report the crystal structure of the fission yeast Tpz1(475-508)-Poz1-Rap1(467-496) complex that provides the structural basis for shelterin bridge assembly...
November 16, 2017: Molecular Cell
https://www.readbyqxmd.com/read/29149595/sterol-oxidation-mediates-stress-responsive-vms1-translocation-to-mitochondria
#7
Jason R Nielson, Eric K Fredrickson, T Cameron Waller, Olga Zurita Rendón, Heidi L Schubert, Zhenjian Lin, Christopher P Hill, Jared Rutter
Vms1 translocates to damaged mitochondria in response to stress, whereupon its binding partner, Cdc48, contributes to mitochondrial protein homeostasis. Mitochondrial targeting of Vms1 is mediated by its conserved mitochondrial targeting domain (MTD), which, in unstressed conditions, is inhibited by intramolecular binding to the Vms1 leucine-rich sequence (LRS). Here, we report a 2.7 Å crystal structure of Vms1 that reveals that the LRS lies in a hydrophobic groove in the autoinhibited MTD. We also demonstrate that the oxidized sterol, ergosterol peroxide, is necessary and sufficient for Vms1 localization to mitochondria, through binding the MTD in an interaction that is competitive with binding to the LRS...
November 16, 2017: Molecular Cell
https://www.readbyqxmd.com/read/29149594/conversion-of-bim-bh3-from-activator-to-inhibitor-of-bak-through-structure-based-design
#8
Jason M Brouwer, Ping Lan, Angus D Cowan, Jonathan P Bernardini, Richard W Birkinshaw, Mark F van Delft, Brad E Sleebs, Adeline Y Robin, Ahmad Wardak, Iris K Tan, Boris Reljic, Erinna F Lee, W Douglas Fairlie, Melissa J Call, Brian J Smith, Grant Dewson, Guillaume Lessene, Peter M Colman, Peter E Czabotar
Certain BH3-only proteins transiently bind and activate Bak and Bax, initiating their oligomerization and the permeabilization of the mitochondrial outer membrane, a pivotal step in the mitochondrial pathway to apoptosis. Here we describe the first crystal structures of an activator BH3 peptide bound to Bak and illustrate their use in the design of BH3 derivatives capable of inhibiting human Bak on mitochondria. These BH3 derivatives compete for the activation site at the canonical groove, are the first engineered inhibitors of Bak activation, and support the role of key conformational transitions associated with Bak activation...
November 16, 2017: Molecular Cell
https://www.readbyqxmd.com/read/29149568/individual-atomic-imaging-of-multiple-dopant-sites-in-as-doped-si-using-spectro-photoelectron-holography
#9
Kazuo Tsutsui, Tomohiro Matsushita, Kotaro Natori, Takayuki Muro, Yoshitada Morikawa, Takuya Hoshii, Kuniyuki Kakushima, Hitoshi Wakabayashi, Kouichi Hayashi, Fumihiko Matsui, Toyohiko Kinoshita
The atomic scale characterization of dopant atoms in semiconductor devices to establish correlations with the electrical activation of these atoms is the essential to the advancement of contemporary semiconductor process technology. Spectro-photoelectron holography combined with first-principles simulations can determine the local three-dimensional atomic structures of dopant elements, which in turn affect their electronic states. In the work reported herein, this technique was used to examine arsenic (As) atoms doped into a silicon (Si) crystal...
November 17, 2017: Nano Letters
https://www.readbyqxmd.com/read/29149501/the-weakly-coordinating-tris-trichlorosilyl-silyl-anion
#10
Marian Olaru, Maxie F Hesse, Elena Rychagova, Sergey Ketkov, Stefan Mebs, Jens Beckmann
Closely following the procedure for the preparation of the base-stabilized dichlorosilylene complex NHCDipp∙SiCl2 by Roesky and Stalke et al. (Angew. Chem. Int. Ed. 2009, 48, 5683-5686), besides the reported by-product [NHCDipp-H+∙∙∙Cl-], few crystals of the salt [NHCDipp-H∙∙∙Cl∙∙∙H-NHCDipp]Si(SiCl3)3 were isolated and characterized by X-ray crystallography (NHCDipp = N,N-di(2,6-isopropylphenyl)-imidazo-2-ylidene). They feature the weakly-coordinating anion Si(SiCl3)3-, which was more rationally obtained in high yields upon deprotonation of conjugate Brønsted acid HSi(SiCl3)3 with NHCDipp or PMP (PMP = 1,2,2,6,6-pentamethylpiperidine)...
November 17, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29149423/structural-and-visible-near%C3%A2-infrared-optical-properties-of-cr-doped-tio2-for-colored-cool-pigments
#11
Le Yuan, Xiaolong Weng, Ming Zhou, Qingyong Zhang, Longjiang Deng
Chromium-doped TiO2 pigments were synthesized via a solid-state reaction method and studied with X-ray diffraction, SEM, XPS, and UV-VIS-NIR reflectance spectroscopy. The incorporation of Cr(3+) accelerates the transition from the anatase phase to the rutile phase and compresses the crystal lattice. Moreover, the particle morphology, energy gap, and reflectance spectrum of Cr-doped TiO2 pigments is affected by the crystal structure and doping concentration. For the rutile samples, some of the Cr(3+) ions are oxidized to Cr(4+) after sintering at a high temperature, which leads to a strong near-infrared absorption band due to the (3)A2 → (3) T1 electric dipole-allowed transitions of Cr(4+)...
November 17, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/29149072/different-inhibitory-potencies-of-oseltamivir-carboxylate-zanamivir-and-several-tannins-on-bacterial-and-viral-neuraminidases-as-assessed-in-a-cell-free-fluorescence-based-enzyme-inhibition-assay
#12
Stefanie Quosdorf, Anja Schuetz, Herbert Kolodziej
Neuraminidaseis a key enzyme in the life cycle of influenza viruses and is present in some bacterial pathogens. We here assess the inhibitory potency of plant tannins versus clinically used inhibitors on both a viral and a bacterial model neuraminidase by applying the 2'-(4-methylumbelliferyl)-α-d-N-acetylneuraminic acid (MUNANA)-based activity assay. A range of flavan-3-ols, ellagitannins and chemically defined proanthocyanidin fractions was evaluated in comparison to oseltamivir carboxylate and zanamivir for their inhibitory activities against viral influenza A (H1N1) and bacterial Vibrio cholerae neuraminidase (VCNA)...
November 17, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29148803/hsdhodh-microdomain-membrane-interactions-are-influenced-by-the-lipid-composition
#13
Eduardo Festozo Vicente, Indra Dev Sahu, Edson Crusca, Luis Guilherme Mansor Basso, Claudia Elisabeth Munte, Antonio Jose Costa-Filho, Gary A Lorigan, Eduardo Maffud Maffud Cilli
Human dihydroorotate dehydrogenase (HsDHODH) enzyme has been studied as selective target for inhibitors to block the enzyme activity, intending to prevent proliferative diseases. The N-terminal microdomain seems to play an important role in the enzyme function. However, the molecular mechanism of action and dynamics of this region are not totally understood yet. This study analyzes the interaction and conformation in model membranes of HsDHODH microdomain using peptide analogues containing the paramagnetic amino acid TOAC at strategic positions...
November 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29148797/nigegladines-a-c-three-thymoquinone-dimers-from-nigella-glandulifera
#14
Jie Tian, Chao Han, Wen-Hua Guo, Yong Yin, Xiao-Bing Wang, Hong-Bin Sun, He-Quan Yao, Yong Yang, Chen Wang, Chang Liu, Ming-Hua Yang, Ling-Yi Kong
Nigegladines A-C (1-3), three thymoquinone dimers, were isolated from the seeds of Nigella glandulifera. Racemic 1 possesses a unique tricyclo[5.4.0.1(2,6)]dodecane carbon skeleton, and compounds 2 and 3 are two unusual diterpenoid alkaloids with indole cores. Their structures were determined by extensive spectroscopic analyses, and that of 1 was confirmed by single-crystal X-ray diffraction. Both (+)-1 and (-)-1 exhibited significant protective effects against hypoxia/reoxygenation-induced H9c2 myocardial cell injury...
November 17, 2017: Organic Letters
https://www.readbyqxmd.com/read/29148783/in-situ-assembly-of-nanoparticles-into-hierarchical-beta-zeolite-with-tailored-simple-organic-molecule
#15
Kai Zhang, Zewei Liu, Xin Yan, Xuelong Hao, Min Wang, Chao Li, Hongxia Xi
A hierarchically structured beta zeolite with intercrystalline mesopores was successfully synthesized via in situ assembly of nanoparticles by employing a simple organic molecule N2-p-N2, tailored form polyquaternium surfactant, with no hydrophobic long chain. The obtained material was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms and computer simulation. These results indicated that the tailored template molecule N2-p-N2 without hydrophobic long chain tail still can direct the zeolite crystallization, the hydrophobic long chain tail is not necessary during the mesoporous Beta zeolite formation...
November 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29148769/azetidine-and-piperidine-carbamates-as-efficient-covalent-inhibitors-of-monoacylglycerol-lipase
#16
Christopher R Butler, Elizabeth M Beck, Anthony R Harris, Zhen Huang, Laura A McAllister, Christopher W Am Ende, Kimberly F Fennell, Timothy L Foley, Kari R Fonseca, Steven J Hawrylik, Douglas S Johnson, John D Knafels, Scot Mente, Stephen Noell, Jayvardhan Pandit, Tracy B Phillips, Justin R Piro, Bruce N Rogers, Tarek A Samad, Jane Wang, Shuangyi Wan, Michael A Brodney
Monoacylglycerol lipase (MAGL) is the main enzyme responsible for degradation of the endocannabinoid 2-arachidonoylglycerol (2-AG) in the CNS. MAGL catalyzes the conversion of 2-AG to arachidonic acid (AA), a precursor to the pro-inflammatory eicosannoids such as prostaglandins. Herein we describe highly efficient MAGL inhibitors, identified through a parallel medicinal chemistry approach that highlighted the improved efficiency of azetidine and piperidine-derived carbamates. The discovery and optimization of 3-substituted azetidine carbamate irreversible inhibitors of MAGL was aided by the generation of inhibitor-bound MAGL crystal structures...
November 17, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/29148734/unraveling-the-role-of-structural-order-in-the-transformation-of-electrical-conductivity-in-ca2fecoo6-%C3%AE-casrfecoo6-%C3%AE-and-sr2fecoo6-%C3%AE
#17
Ram Krishna Hona, Ashfia Huq, Farshid Ramezanipour
The ability to control the electrical conductivity of solid-state oxides using structural parameters has been demonstrated. A correlation has been established between the electrical conductivity and structural order in a series of oxygen-deficient perovskites using X-ray and neutron diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and electrical conductivity studies at a wide temperature range, 25-800 °C. The crystal structure of CaSrFeCoO6-δ has been determined, and its stark contrast to Ca2FeCoO6-δ and Sr2FeCoO6-δ has been demonstrated...
November 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/29148728/neutral-luminescent-metal-organic-frameworks-structural-diversification-photophysical-properties-and-sensing-applications
#18
Gouri Chakraborty, Sanjay K Mandal
Utilizing flexible bis(tridentate)polypyridyl ligands, the two new luminescent 2D metal organic frameworks {Zn2(tpbn)(2,6-NDC)2}n (1) and {[Zn2(tphn)(2,6-NDC)2]·4H2O}n (2), where tpbn = N,N',N″,N‴-tetrakis(2-pyridylmethyl)-1,4-diaminobutane, tphn = N,N',N″,N‴-tetrakis(2-pyridylmethyl)-1,6-diaminohexane, and 2,6-H2NDC = 2,6-naphthalenedicarboxylic acid, have been isolated in good yields under solvothermal conditions. Their solid-state molecular structures have been determined by single-crystal X-ray diffractometry...
November 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/29148718/atomic-layer-deposition-of-single-crystalline-beo-epitaxially-grown-on-gan-substrates
#19
Seung Min Lee, Jung Hwan Yum, Seonno Yoon, Eric S Larsen, Woo Chul Lee, Seong Keun Kim, Shahab Shervin, Weijie Wang, Jae-Hyun Ryou, Christopher W Bielawski, Jungwoo Oh
We have developed a beryllium oxide (BeO) thin film process by atomic layer deposition (ALD) and grown a single-crystal BeO on a gallium nitride (GaN) substrate for the first time. BeO has a higher thermal conductivity than all other metals except Cu, Ag, and Au, and it has a higher bandgap energy and dielectric constant than SiO2 and Al2O3. As an electrical insulator, diamond is the only material on Earth whose thermal conductivity exceeds that of BeO. Despite these advantages, there is no chemical vapor deposition technique for BeO thin film deposition, and thus, it is not used in nanoscale semiconductor device processing...
November 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29148711/rational-manipulation-of-iro2-lattice-strain-on-%C3%AE-mno2-nanorods-as-a-highly-efficient-water-splitting-catalyst
#20
Wei Sun, Zhenhua Zhou, Waqas Qamar Zaman, Li-Mei Cao, Ji Yang
Developing more efficient and stable oxygen evolution reaction (OER) catalysts is critical for future energy conversion and storage technologies. We demonstrate that inducing a lattice strain in IrO2 crystal structure due to interface lattice mismatch enables an enhancement of the OER catalytic activity. The lattice strain is obtained by the direct growth of IrO2 nanoparticles on a specially exposed surface of α-MnO2 nanorods via a simple two-step hydrothermal synthesis. Interestingly, the prepared hydride OER activity increases with a lower IrO2 grown mass, which offers an opportunity to reduce the usage of precious iridium and ultimately obtains a specific mass activity of 3...
November 17, 2017: ACS Applied Materials & Interfaces
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