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crystal structure transporter

Daiki Tatsumi, Kei Nanatani, Yuto Koike, Kiyoto Kamagata, Satoshi Takahashi, Ayumu Konno, Tadaomi Furuta, Minoru Sakurai, Nobuyuki Uozumi
ATP binding cassette (ABC) transporters are ubiquitously present in prokaryotic and eukaryotic cells. Binding of ATP to the nucleotide binding domains (NBDs) elicits major conformational changes of the transporters resulting in the transport of the substrate across the membrane. The availability of a crystal structure of the NBDs enabled us to elucidate the local structure and small-scale dynamics in the NBDs. Here, we labeled the ABC transporter MsbA, a homodimeric flippase from E. coli , with a fluorescent probe, Alexa532, within the NBDs...
April 21, 2017: Biochemical Journal
Alayna M George Thompson, Cristina V Iancu, Kenneth E Neet, John V Dean, Jun-Yong Choe
Salicylic acid (SA) is a signaling molecule utilized by plants in response to various stresses. Through conjugation with small organic molecules such as glucose, an inactive form of SA is generated which can be transported into and stored in plant vacuoles. In the model organism Arabidopsis thaliana, SA glucose conjugates are formed by two homologous enzymes (UGT74F1 and UGT74F2) that transfer glucose from UDP-glucose to SA. Despite being 77% identical and with conserved active site residues, these enzymes catalyze the formation of different products: UGT74F1 forms salicylic acid glucoside (SAG), while UGT74F2 forms primarily salicylic acid glucose ester (SGE)...
April 20, 2017: Scientific Reports
Marscha Hirschi, Zachary Lee Johnson, Seok-Yong Lee
Membrane transporters move substrates across the membrane by alternating access of their binding sites between the opposite sides of the membrane. An emerging model of this process is the elevator mechanism, in which a substrate-binding transport domain moves a large distance across the membrane. This mechanism has been characterized by a transition between two states, but the conformational path that leads to the transition is not yet known, largely because the available structural information has been limited to the two end states...
April 17, 2017: Nature
Juan C Canul-Tec, Reda Assal, Erica Cirri, Pierre Legrand, Sébastien Brier, Julia Chamot-Rooke, Nicolas Reyes
Human members of the solute carrier 1 (SLC1) family of transporters take up excitatory neurotransmitters in the brain and amino acids in peripheral organs. Dysregulation of the function of SLC1 transporters is associated with neurodegenerative disorders and cancer. Here we present crystal structures of a thermostabilized human SLC1 transporter, the excitatory amino acid transporter 1 (EAAT1), with and without allosteric and competitive inhibitors bound. The structures reveal architectural features of the human transporters, such as intra- and extracellular domains that have potential roles in transport function, regulation by lipids and post-translational modifications...
April 19, 2017: Nature
Tatyana V Rodionova, Artem A Sizikov, Vladislav Yu Komarov, Galina V Villevald, Tamara D Karpova, Andrey Yu Manakov
In the present work we studied semiclathrate hydrates in the TBPO ‒ H2O and TBPO ‒ H2O ‒ CH4 systems. The stoichiometry, temperature and enthalpy of dissociation of TBPO semiclathrate hydrate crystals formed in TBPO - H2O binary system were found to be TBPO·33.6±0.9Н2О, 280.0 K, and 253.1±4.7 Jg(-1), respectively. The crystal structure determined by single crystal XRD analysis (150 K) was orthorhombic with space group Pbam and unit cell parameters a =19.9313(8) Å, b =23.4660(7) Å, c =12.1127(5) Å...
April 19, 2017: Journal of Physical Chemistry. B
Cairong Jiang, Jianjun Ma, Gael Corre, Sneh L Jain, John T S Irvine
A direct carbon fuel cell (DCFC) can produce electricity with both superior electrical efficiency and fuel utilisation compared to all other types of fuel cells. Although the first DCFC prototype was proposed in 1896, there was, until the 1970s, little sustained effort to investigate further, because of technology development issues. Interest in DCFCs has recently been reinvigorated as a possible method of replacing conventional coal-fired power plants to meet the demands for lower CO2 emissions, and indeed for efficient utilisation of waste derived chars...
April 19, 2017: Chemical Society Reviews
Camilo Perez, Martin Köhler, Daniel Janser, Els Pardon, Jan Steyaert, Renato Zenobi, Kaspar P Locher
PglK is an ABC transporter that flips a lipid-linked oligosaccharide (LLO) that serves as a donor in protein N-glycosylation. Previous structures revealed two inward-facing conformations, both with very large separations of the nucleotide binding domains (NBDs), and a closed, ADP-bound state that featured an occluded cavity. To investigate additional states, we developed conformation-sensitive, single-domain camelid nanobodies (Nb) and studied their effect on PglK activity. Biochemical, structural, and mass spectrometric analyses revealed that one inhibitory Nb binds as a single copy to homodimeric PglK...
April 19, 2017: Scientific Reports
Yuji Hirai, Hiroyuki Mayama, Yasutaka Matsuo, Masatsugu Shimomura
In nature, there exist a number of functional water-controlling surfaces, such as the water-repellent surface of lotus leaves, the superhydrophobic water-adhesive surface of rose petals, the water-harvesting surface of a beetle's back, and the water-transporting surface of the legs of Ligia exotica. These natural surfaces suggest that surface chemistry and hierarchical structures are essential for controlling water behavior. We have reported the preparation of superhydrophobic and anti-reflection silicon nanospike-array structures using self-organized honeycomb-patterned films as 3D dry etching masks...
April 19, 2017: ACS Applied Materials & Interfaces
Guangwei Geng, Penglei Chen, Bo Guan, Lang Jiang, Zhongfei Xu, Dawei Di, Zeyi Tu, Weichang Hao, Yuanping Yi, Chuncheng Chen, Minghua Liu, Wenping Hu
Metal-free catalytic materials have recently received broad attention as promising alternatives to metal-involved catalysts. This is owing to their inherent capability to overcome the inevitable limitations of metal-involved catalysts, such as high sensitivity to poisoning, the limited reserves, high cost and scarcity of metals (especially noble metals), etc. However, the lack of shape-controlled metal-free catalysts with well-defined facets is a formidable bottleneck limiting our understandings on the underlying structure-activity relationship at atomic/molecular level, which thereby restrains their rational design...
April 19, 2017: ACS Nano
Choongdeok Lee, Meong Il Kim, Jaewan Park, Bo-Young Jeon, Sung-Il Yoon, Minsun Hong
FliS is a cytoplasmic flagellar chaperone for the flagellin, which polymerizes into filaments outside of the flagellated bacteria. Cytoplasmic interaction between FliS and flagellin is critical to retain the flagellin protein in a monomeric form, which is transported from the cytoplasm through the flagellar export apparatus to the extracellular space for filament assembly. Defects in the FliS protein directly diminish bacterial motility, pathogenicity, and viability. Although the overall structure of FliS is known, structural and mutational studies on FliS from other bacterial species are still required to reveal any unresolved biophysical features of FliS itself or functionally critical residues for flagellin recognition...
April 14, 2017: Biochemical and Biophysical Research Communications
Pravin S Dewangan, Parshuram J Sonawane, Ankita Rai Chouksey, Radha Chauhan
The central transport channel of vertebrate nuclear pore complex (NPCs) is made up of nucleoporins: Nup62, Nup54 and Nup58. The coiled-coil domains in α-helical regions of these nucleoporins are thought to be crucial for several protein-protein interactions in the NPC sub-complexes. In this study, we determined the crystal structure of the coiled-coil domain of rat Nup62 fragment (362-425) to 2.4 Å resolution. The crystal structure shows conserved coiled-coil domain as a parallel three helix bundle for the Nup62(362-425) fragment...
April 13, 2017: Biochemistry
Anna K Hailey, Anthony J Petty, Jennifer Washbourne, Karl J Thorley, Sean R Parkin, John E Anthony, Yueh-Lin Loo
In order to understand how additives influence the structure and electrical properties of active layers in thin-film devices, a compositionally identical but structurally different guest-host system based on the syn and anti isomers of triethylsilylethynyl anthradithiophene (TES ADT) is systematically explored. The mobility of organic thin-film transistors (OTFTs) comprising anti TES ADT drops with the addition of only 0.01% of the syn isomer and is pinned at the mobility of OTFTs having pure syn isomer after the addition of only 10% of the isomer...
April 12, 2017: Advanced Materials
Qingshan Luo, Xu Yang, Shan Yu, Huigang Shi, Kun Wang, Le Xiao, Guangyu Zhu, Chuanqi Sun, Tingting Li, Dianfan Li, Xinzheng Zhang, Min Zhou, Yihua Huang
After biosynthesis, bacterial lipopolysaccharides (LPS) are transiently anchored to the outer leaflet of the inner membrane (IM). The ATP-binding cassette (ABC) transporter LptB2FG extracts LPS molecules from the IM and transports them to the outer membrane. Here we report the crystal structure of nucleotide-free LptB2FG from Pseudomonas aeruginosa. The structure reveals that lipopolysaccharide transport proteins LptF and LptG each contain a transmembrane domain (TMD), a periplasmic β-jellyroll-like domain and a coupling helix that interacts with LptB on the cytoplasmic side...
April 10, 2017: Nature Structural & Molecular Biology
Ruifang Guan, Lei Zhang, Qian Peter Su, Keith J Mickolajczyk, Geng-Yuan Chen, William O Hancock, Yujie Sun, Yongfang Zhao, Zhucheng Chen
Kinesins hydrolyse ATP to transport intracellular cargoes along microtubules. Kinesin neck linker (NL) functions as the central mechano-chemical coupling element by changing its conformation through the ATPase cycle. Here we report the crystal structure of kinesin-6 Zen4 in a nucleotide-free, apo state, with the NL initial segment (NIS) adopting a backward-docked conformation and the preceding α6 helix partially melted. Single-molecule fluorescence resonance energy transfer (smFRET) analyses indicate the NIS of kinesin-1 undergoes similar conformational changes under tension in the two-head bound (2HB) state, whereas it is largely disordered without tension...
April 10, 2017: Nature Communications
Ellis J Wilde, Adam Hughes, Elena V Blagova, Olga V Moroz, Ross P Thomas, Johan P Turkenburg, Daniel J Raines, Anne-Kathrin Duhme-Klair, Keith S Wilson
Bacteria use siderophores to mediate the transport of essential Fe(III) into the cell. In Campylobacter jejuni the periplasmic binding protein CeuE, an integral part of the Fe(III) transport system, has adapted to bind tetradentate siderophores using a His and a Tyr side chain to complete the Fe(III) coordination. A series of tetradentate siderophore mimics was synthesized in which the length of the linker between the two iron-binding catecholamide units was increased from four carbon atoms (4-LICAM(4-)) to five, six and eight (5-, 6-, 8-LICAM(4-), respectively)...
April 6, 2017: Scientific Reports
Jishan Wu, Qingbiao Qi, Paula Mayorga Burrezo, Hoa Phan, Tun Seng Herng, Tullimilli Y Gopalakrishna, Wangdong Zeng, Jun Ding, Juan Casado
Radical cations and dications of π-conjugated systems play vital roles in organic electronic devices, organic conductors, and conducting polymers. Their structures, charge and spin distribution, and mechanism of charge transport are of great interest. In this article, radical cations and dications of a series of newly synthesized methylthio-capped rylenes were synthesized and isolated. Their ground-state structures, physical properties, and solid state packing were systematically investigated by various experimental methods such as X-ray crystallographic analysis, UV-vis-NIR absorption, (spectro-) electrochemistry, nuclear magnetic resonance, electron spin resonance, superconducting quantum interference device and Raman spectroscopy, assisted by DFT calculations...
April 5, 2017: Chemistry: a European Journal
Dipankar Saha, Santanu Mahapatra
The investigation of crystallographic orientation dependent carrier transport in a material could lead to novel electronic devices and circuit applications. Although the out-of-plane carrier transport in layered transition metal dichalcogenides (TMDs) is expected to differ from its normal counterpart, in-plane anisotropy is not so common in such materials. The symmetric honeycomb structure of a semiconducting 2H phase MoS2 crystal limits the in-plane anisotropy. However such possibility in a distorted 1T phase i...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
Eli Fernández-de Gortari, L Michel Espinoza-Fonseca
We have performed microsecond molecular dynamics (MD) simulations to determine the mechanism for protonation-dependent structural transitions of the sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA), one of the most prominent members of the large P-type ATPase superfamily that transports ions across biological membranes. The release of two H(+) from the transport sites activates SERCA by inducing a structural transition between low (E2) and high (E1) Ca(2+)-affinity states (E2-to-E1 transition), but the structural mechanism by which transport site deprotonation facilitates this transition is unknown...
April 12, 2017: Physical Chemistry Chemical Physics: PCCP
Marko Poppe, Changlon Chen, Feng Liu, Silvio Poppe, Carsten Tschierske
Bicontinuous cubic phases are of significant importance for numerous applications, for example, for the crystallization of membrane proteins, as photonic materials and as templates for porous silica. A new variant of bicontinuous cubic liquid crystalline phase with Ia3¯d lattice is reported here for X-shaped bolapolyphiles. It is shown that in this class of compounds cubic phase induction can be achieved by proper aromatic core fluorination; in addition, the first cubic phases having π-conjugated oligo(phenylene ethynylene) rods on the gyroid minimal surface were obtained...
March 29, 2017: Chemistry: a European Journal
Constanze Homburg, Martin Bommer, Steven Wuttge, Carolin Hobe, Sebastian Beck, Holger Dobbek, Josef Deutscher, Anke Licht, Erwin Schneider
Catabolite repression is a mechanism that enables bacteria to control carbon utilization. As part of this global regulatory network, components of the phosphoenolpyruvate:carbohydrate phosphotransferase system inhibit the uptake of less favourable sugars when a preferred carbon source such as glucose is available. This process is termed inducer exclusion. In bacteria belonging to the phylum Firmicutes, HPr, phosphorylated at serine 46 (P-Ser46-HPr) is the key player but its mode of action is elusive. To address this question at the level of purified protein components, we have chosen a homolog of the E...
March 30, 2017: Molecular Microbiology
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