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crystal structure transporter

Zhenning Ren, Jumin Lee, Mahdi Muhammad Moosa, Yin Nian, Liya Hu, Zhichun Xu, Jason G McCoy, Allan Chris M Ferreon, Wonpil Im, Ming Zhou
The phosphoenolpyruvate-dependent phosphotransferase system (PTS) transports sugar into bacteria and phosphorylates the sugar for metabolic consumption. The PTS is important for the survival of bacteria and thus a potential target for antibiotics, but its mechanism of sugar uptake and phosphorylation remains unclear. The PTS is composed of multiple proteins, and the membrane-embedded Enzyme IIC (EIIC) component transports sugars across the membrane. Crystal structures of two members of the glucose superfamily of EIICs, bcChbC and bcMalT, were solved in the inward-facing and outward-facing conformations, and the structures suggest that sugar translocation could be achieved by movement of a structured domain that contains the sugar-binding site...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
Avik Chatterjee, Eun Jin Yu, Lindsay Tishberg
BACKGROUND: Opioid Use Disorder (OUD) causes significant morbidity and mortality among people experiencing homelessness. We aimed to explore the unique way in which OUD impacts individuals experiencing homelessness as part of a family. METHODS: We conducted semi-structured interviews with adults experiencing OUD staying in Boston-area family shelters along with dependent children. We used Borkan's Immersion-Crystallization method to uncover themes from interview transcripts...
May 12, 2018: Drug and Alcohol Dependence
Xiang Wang, Zeyuan Guan, Zhou Gong, Junjie Yan, Guangsheng Yang, Yao-Guang Liu, Ping Yin
Plant cytoplasmic male sterility (CMS) is an important phenomenon and is widely utilized in hybrid crop breeding. The Wild Abortive CMS (CMS-WA), a well-known CMS type, has been successfully applied in the commercial production of hybrid rice seeds for more than 40 years. The CMS-WA causal gene WA352 encodes a novel transmenbrane protein and the interacts with the mitochondrial copper chaperone COX11, triggering reactive oxygen species production and resulting in male sterility in CMS-WA lines. However, the structure of WA352 is currently unknown, and the structural mechanism whereby WA352 perturbs COX11 function to cause CMS remains largely unknown...
May 15, 2018: Biochemical and Biophysical Research Communications
Selma Sassi, Christophe Candolfi, Anne Dauscher, Bertrand Lenoir, Michael Marek Koza
We report on the inelastic response of the homologous compounds (PbSe)5(Bi2Se3)3m for m = 1, 2 and 3 followed in a broad temperature range (50-500 K) using high-resolution powder inelastic neutron scattering experiments. These results are complemented by low-temperature measurements of the specific heat (2-300 K). The evolution of the anisotropic crystal structure of these compounds with varying m, built from alternate Pb-Se and mBi-Se layers, only weakly influences the generalized phonon density of states...
May 16, 2018: Physical Chemistry Chemical Physics: PCCP
Kangsa Amporndanai, Rachel M Johnson, Paul M O'Neill, Colin W G Fishwick, Alexander H Jamson, Shaun Rawson, Stephen P Muench, S Samar Hasnain, Svetlana V Antonyuk
Cytochrome bc 1 , a dimeric multi-subunit electron-transport protein embedded in the inner mitochondrial membrane, is a major drug target for the treatment and prevention of malaria and toxoplasmosis. Structural studies of cytochrome bc 1 from mammalian homologues co-crystallized with lead compounds have underpinned structure-based drug design to develop compounds with higher potency and selectivity. However, owing to the limited amount of cytochrome bc 1 that may be available from parasites, all efforts have been focused on homologous cytochrome bc 1 complexes from mammalian species, which has resulted in the failure of some drug candidates owing to toxicity in the host...
March 1, 2018: IUCrJ
Andreas Ejdrup Lauritzen, Mika Torkkeli, Oier Bikondoa, Jes Linnet, Luciana Tavares, Jakob Kjelstrup-Hansen, Matti Knaapila
We report on the structure and morphology of 5,5'-bis(naphth-2-yl)- 2,2'-bithiophene (NaT2) films in bottom-contact organic field-effect transistors (OFETs) with octadecyltrichlorosilane (OTS) coated SiO2 gate dielectric, characterized by atomic force microscopy (AFM), grazing-incidence X-ray diffraction (GIXRD) and electrical transport measurements. Three types of devices were investigated with the NaT2 thin-film deposited either on (1) pristine SiO2 (corresponding to higher surface energy, 47 mJ/m2) or on OTS deposited on SiO2 under (2) anhydrous or (3) humid conditions (corresponding to lower surface energies, 20-25 mJ/m2)...
May 11, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Ananya Banik, Subhajit Roychowdhury, Kanishka Biswas
Lead chalcogenides and their alloys belong at the heart of thermoelectrics due to their large thermoelectric figure of merit (zT). However, recent research has shown a limitation in the use of lead (Pb)-based materials due to their toxicity and efforts have been made to produce non-toxic analogues of lead chalcogenides. Tin chalcogenides have been predicted to be promising for this purpose due to their unique electronic structure and phonon dispersion properties. Here, we discuss the journey of tin chalcogenides in the field of thermoelectrics and topological materials with the main emphasis on the bonding, crystal structures, electronic band structures, phonon dispersion and thermoelectric properties...
May 11, 2018: Chemical Communications: Chem Comm
Jiyu Li, Lihua Wang, Lu Zheng, Yuerong Wang, Xi Chen, Wei Zhang
Arabidopsis thaliana natural resistance-associated macrophage protein 3 (AtNRAMP3) is involved in the transport of cadmium (Cd), iron (Fe), and manganese (Mn). Here, we present a structure-function analysis of AtNRAMP3 based on site-directed mutagenesis and metal toxicity growth assays involving yeast mutants, combined with three-dimensional (3D) structure modeling based on the crystal structure of the Eremococcus coleocola NRAMP family transporter, EcoDMT. We demonstrated that two conservative sites, D72 and N75, are essential for the transport activity...
May 10, 2018: International Journal of Molecular Sciences
Tianyue Li, Qifei Wang, Gary S Nichol, Carole A Morrison, Hongwei Han, Yue Hu, Neil Robertson
We report on the synthesis, crystal structures, optoelectronic properties and solar cell device studies of three novel organic-inorganic iodobismuthates - [C3H4NS]3[Bi2I9] ([TH]3[Bi2I9]), [C3H4N2]3[Bi2I9] ([IM]3[Bi2I9]) and [C3H5N2S][BiI4] ([AT][BiI4]) as lead-free light harvesters. [TH]3[Bi2I9] and [IM]3[Bi2I9] show zero-dimensional structures, whereas a one-dimensional edge-sharing chain structure of BiI6-octahedra was observed in [AT][BiI4], with interchain short II contacts also giving rise to the possibility of three-dimensional charge transport ability...
May 9, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Daniele Martella, Camilla Parmeggiani
Recent discoveries evidenced that many cells organize into well-aligned nematic domains, showing also their topological defects and suggesting the liquid crystalline order to be necessary for some biological functions. These evidences were described as the basis for the development of a new area of research in which polymeric liquid crystals were developed to exploit and promote cell adhesion and proliferation towards tissue regeneration. To address the requirements of tissue engineering, new biocompatible materials must be designed and synthesized to support cell adherence and growth together with nutrient transport under physiological condition...
March 8, 2018: Chemistry: a European Journal
Sean D Liston, Stephen A McMahon, Audrey Le Bas, Michael D L Suits, James H Naismith, Chris Whitfield
Capsules are surface layers of hydrated capsular polysaccharides (CPSs) produced by many bacteria. The human pathogen Salmonella enterica serovar Typhi produces "Vi antigen" CPS, which contributes to virulence. In a conserved strategy used by bacteria with diverse CPS structures, translocation of Vi antigen to the cell surface is driven by an ATP-binding cassette (ABC) transporter. These transporters are engaged in heterooligomeric complexes proposed to form an enclosed translocation conduit to the cell surface, allowing the transporter to power the entire process...
May 7, 2018: Proceedings of the National Academy of Sciences of the United States of America
Mingjing Zhu, Shuang Pan, Yue Wang, Ping Tang, Feng Qiu, Zhiqun Lin, Juan Peng
The ability to capitalize on the cocrystallization strategy involving two or more components aggregating into cocrystals renders the creation of materials and devices with markedly improved charge mobility. This, however, has yet to be largely explored in all-conjugated block copolymers (BCPs). Herein, we report on the first investigation into the correlation between cocrystals and charge mobility in a series of new all-conjugated BCPs, namely, poly(3-butylthiophene)-b-poly(3-hexylselenophene) (P3BT-b-P3HS) with varied P3BT/P3HS block ratios for high-performance field-effect transistors...
May 7, 2018: Angewandte Chemie
Peter C Loewen, P Malaka De Silva, Lynda J Donald, Jacek Switala, Jacylyn Villanueva, Ignacio Fita, Ayush Kumar
Resistance to antibiotics has become a serious problem for society, and there are increasing efforts to understand the reasons for and sources of resistance. Bacterial-encoded enzymes and transport systems, both innate and acquired, are the most frequent culprits for the development of resistance, although in Mycobacterium tuberculosis , the catalase-peroxidase, KatG, has been linked to the activation of the antitubercular drug isoniazid. While investigating a possible link between aminoglycoside antibiotics and the induction of oxidative bursts, we observed that KatG reduces susceptibility to aminoglycosides...
April 30, 2018: ACS Omega
Xiaoyan Cong, Zenglin Yuan, Zhi Wang, Bin Wei, Sujuan Xu, Jinbao Wang
The pathogenic Mycobacterium tuberculosis encodes two members of the DtxR family metalloregulators, IdeR and MntR. IdeR represses gene expression in response to ferrous iron, while MntR (Rv2788) functions as a manganese-dependent transcriptional repressor, which represses the expression of manganese transporter genes to maintain manganese homeostasis. Although the structural study towards IdeR is in-depth, there is no MntR structure available. Herein, we report both apo and manganese bound forms of MntR structures from M...
May 3, 2018: Biochemical and Biophysical Research Communications
Silvia Orlandi, Claudio Zannoni
We have studied liquid crystal phases formed by fullerenes functionalized with mesogenic groups yielding a cone-shaped molecular structure. We have modelled these shuttlecock-like molecules with a set of Gay-Berne particles grafted with flexible springs to a spherical core and we have studied, using Monte Carlo simulations, their phase organization, also with a view to examining their possible use as candidate organic photovoltaic materials. We have found that, upon cooling from the isotropic phase, the system forms a columnar phase, like in the experimental work of Kato and coworkers [T...
May 4, 2018: Soft Matter
Ilya V Kornyakov, Sergey V Krivovichev, Vladislav V Gurzhiy, Matteo Leoni
A novel polymorph of RbCuCl3 (rubidium copper trichloride), denoted ℇ-RbCuCl3 , has been prepared by chemical vapour transport (CVT) from a mixture of CuO, CuCl2 , SeO2 and RbCl. The new polymorph crystallizes in the orthorhombic space group C2221 . The crystal structure is based on an octahedral framework of the 4H perovskite type. The Rb+ and Cl- ions form a four-layer closest-packing array with an ABCB sequence. The Cu2+ cations reside in octahedral cavities with a typical [4 + 2]-Jahn-Teller-distorted coordination, forming four short and two long Cu-Cl bonds...
May 1, 2018: Acta Crystallographica. Section C, Structural Chemistry
Hengdi Zhao, Jasminka Terzic, Hao Zheng, Yifei Ni, Yu Zheng, Feng Ye, Pedro Schlottmann, Gang Cao
We report a systematical structural, transport and magnetic study of Ca or Ba doped Sr2IrO4 single crystals. Isoelectronically substituting Ca2+ (up to 15%) or Ba2+ (up to 4%) ion for the Sr2+ ion provides no additional charge carriers but effectively changes the lattice parameters in Sr2IrO4. In particular, 15% Ca doping considerably compresses the c-axis and the unit cell by nearly 0.45% and 1.00 %, respectively. These significant, anisotropic compressions in the lattice parameters conspicuously cause no change in the Néel temperature which remains at 240 K, but drastically reduces the electrical resistivity by up to five orders of magnitude or even precipitates a sharp insulator-to-metal transition at lower temperatures, i...
May 3, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Stanislav Chizhik, Anatoly Sidelnikov, Boris Zakharov, Panče Naumov, Elena Boldyreva
Photomechanically reconfigurable elastic single crystals are the key elements for contactless, timely controllable and spatially resolved transduction of light into work from the nanoscale to the macroscale. The deformation in such single-crystal actuators is observed and usually attributed to anisotropy in their structure induced by the external stimulus. Yet, the actual intrinsic and external factors that affect the mechanical response remain poorly understood, and the lack of rigorous models stands as the main impediment towards benchmarking of these materials against each other and with much better developed soft actuators based on polymers, liquid crystals and elastomers...
February 28, 2018: Chemical Science
Yong Ju Kim
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a glycolytic enzyme, catalyses the conversion of D-glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate. While mammalian and yeast GAPDHs are multifunctional proteins that have additional functions beyond those involved in glycolysis, including reactions related to nuclear RNA transport, DNA replication/repair, membrane fusion and cellular apoptosis, Escherichia coli GAPDH (ecGAPDH) has only been reported to function in glycolysis. The S-loop of GAPDH is required for interaction with its cofactor and with other proteins...
May 1, 2018: Acta Crystallographica. Section F, Structural Biology Communications
Mingchao Zhang, Ke Chen, Chunya Wang, Muqiang Jian, Zhe Yin, Zhenglian Liu, Guo Hong, Zhongfan Liu, Yingying Zhang
3D graphene networks have shown extraordinary promise for high-performance electrochemical devices. Herein, the chemical vapor deposition synthesis of a highly porous 3D graphene foam (3D-GF) using naturally abundant calcined Iceland crystal as the template is reported. Intriguingly, the Iceland crystal transforms to CaO monolith with evenly distributed micro/meso/macropores through the releasing of CO2 at high temperature. Meanwhile, the hierarchical structure of the calcined template could be easily tuned under different calcination conditions...
May 2, 2018: Small
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