检索结果-内蒙古大学图书馆

Mutual relationships between structural and functional changes in a PsbM-deletion mutant of photosystem II

FARADAY DISCUSSIONS 2017年第0期198卷 107-120页

作者： Uto, S. Kawakami, K. Umena, Y. Iwai, M. Ikeuchi, M. Shen, J. -R. Kamiya, N. Osaka City Univ Grad Sch Sci Dept Chem Osaka Japan Osaka City Univ OCU Adv Res Inst Nat Sci & Technol OCARINA Osaka Japan JST PRESTO Kawaguchi Saitama Japan Tokyo Inst Technol Grad Sch Biosci & Biotechnol Yokohama Kanagawa Japan Univ Tokyo Grad Sch Arts & Sci Dept Life Sci Biol Tokyo Japan Okayama Univ Res Inst Interdisciplinary Sci Okayama Japan

Photosystem II (PSII) is a membrane protein complex that performs light-induced electron transfer and oxygen evolution from water. PSII consists of 19 or 20 subunits in its crystal form and binds various cofactors such as chlorophyll a, plastoquinone, carotenoid, and lipids. After initial light excitation, the charge separation produces an electron, which is transferred to a plastoquinone molecule (Q(A)) and then to another plastoquinone (Q(B)). PsbM is a low-molecular-weight subunit with one transmembrane helix, and is located in the monomer-monomer interface of the PSII dimer. The function of PsbM has been reported to be stabilization of the PSII dimer and maintenance of electron transfer efficiency of PSII based on previous X-ray crystal structure analysis at a resolution of 4.2 angstrom. In order to elucidate the structure-function relationships of PsbM in detail, we improved the quality of PSII crystals from a PsbM-deleted mutant (Delta PsbM-PSII) of Thermosynechococcus elongatus, and succeeded in improving the diffraction quality to a resolution of 2.2 angstrom. X-ray crystal structure analysis of Delta PsbM-PSII showed that electron densities for the PsbM subunit and neighboring carotenoid and detergent molecules were absent in the monomer-monomer interface. The overall structure of Delta PsbM-PSII was similar to wild-type PSII, but the arrangement of the hydrophobic transmembrane subunits was significantly changed by the deletion of PsbM, resulting in a slight widening of the lipid hole involving Q(B). The lipid hole-widening further induced structural changes of the bicarbonate ion coordinated to the non-heme Fe(II) atom and destabilized the polypeptide chains around the Q(B) binding site located far from the position of PsbM. The fluorescence decay measurement indicated that the electron transfer rate from Q(A) to Q(B) was decreased in DPsbM-PSII compared with wild-type PSII. The functional change in electron transfer efficiency was fully interpreted based

关键词： Quality assurance structure-function relationships Electron density Photosystem II Redox processes Plastoquinone TRANSFER EFFICIENCY Lipids Deletion mutant bicarbonate ion crystal outline Membrane Proteins electron transfer Resolving power

来源：评论

学校读者我要写书评

暂无评论

Responses of sapwood ray parenchyma and non-structural carbohydrates of Pinus sylvestris to drought and long-term irrigation

引用

functionAL ECOLOGY 2017年第7期31卷 1371-1382页

作者： von Arx, Georg Arzac, Alberto Fonti, Patrick Frank, David Zweifel, Roman Rigling, Andreas Galiano, Lucia Gessler, Arthur Miguel Olano, Jose Swiss Fed Inst Forest Snow & Landscape Res WSL Zuercherstr 111 CH-8903 Birmensdorf Switzerland SwissForestLab Zuercherstr 111 CH-8903 Birmensdorf Switzerland Siberian Fed Univ Sch Ecol & Geog 79 Svobodny Pr Krasnoyarsk 660041 Russia Univ Basque Country Fac Ciencia & Tecnol Dept Biol Vegetal & Ecol Barrio Sarriena S-N E-48940 Leioa Spain Univ Arizona Tree Ring Res Lab Tucson AZ 85721 USA iuFOR Univ Valladolid Dept Ciencias Agroforestales EU Ingn Agr Campus Duques Soria Soria 42004 Spain

1. Non-structural carbohydrates (NSC) play a crucial role in tree resistance and resilience to drought. Stem sapwood parenchyma is among the largest storage tissue for NSC in mature trees. However, there is a limited mechanistic understanding of how NSC reserves, stem parenchyma abundance and growth rates are interrelated, and how they respond to changing water availability. 2. We quantified NSC, ray parenchyma abundance and ring width along four successive 5-year radial sapwood segments of the stem of 40 mature Pinus sylvestris trees from a 10-year irrigation experiment conducted at a xeric site in Switzerland. 3. Percentage of ray volume (PERPAR) varied from 3.75 to 8.94% among trees, but showed low intra-individual variability. PERPAR responded positively to irrigation with a lag of several years, but was unrelated to %NSC. %NSC was lower in wider rings. However, wider rings still contained a larger NSC pool that was positively related to next year's ring growth. 4. Our results suggest that stem ray parenchyma does not limit NSC storage capacity, but responds to long-term environmental drivers with years of delay. The observed carbon allocation patterns indicate a prioritization of storage over growth independent of growth conditions, likely as a mechanism to ensure long-term survival. Furthermore, NSC pool size proved to be a determinant for the inter-annual autocorrelation in tree-ring growth. Our study highlights the importance of long-term multi-parameter studies to better understand tree responses to environmental variability at different time-scales.

关键词： carbon allocation drought stress growth vs storage ring-width autocorrelation structure-function relationships tree-ring anatomy xylem anatomy xylem rays

来源：评论

学校读者我要写书评

暂无评论

The anatomy of mammalian sweet taste receptors

引用

PROTEINS-structure function AND BIOINFORMATICS 2017年第2期85卷 332-341页

作者： Cheron, Jean-Baptiste Golebiowski, Jerome Antonczak, Serge Fiorucci, Sebastien Univ Cote Azur Inst Chim Nice CNRS UMR7272 F-06108 Nice France DGIST Daegu Gyeongbuk Inst Sci & Technol Dept Brain & Cognit Sci Daegu South Korea

All sweet-tasting compounds are detected by a single G-protein coupled receptor (GPCR), the heterodimer T1R2-T1R3, for which no experimental structure is available. The sweet taste receptor is a class C GPCR, and the recently published crystallographic structures of metabotropic glutamate receptor (mGluR) 1 and 5 provide a significant step forward for understanding structure-function relationships within this family. In this article, we recapitulate more than 600 single point site-directed mutations and available structural data to obtain a critical alignment of the sweet taste receptor sequences with respect to other class C GPCRs. Using this alignment, a homology 3D-model of the human sweet taste receptor is built and analyzed to dissect out the role of key residues involved in ligand binding and those responsible for receptor activation. Proteins 2017;85:332-341. (c) 2016 Wiley Periodicals, Inc.

关键词： chemical senses sweet taste GPCR T1R class C structure-function relationships

来源：评论

学校读者我要写书评

暂无评论

A jasmonic acid derivative improves skin healing and induces changes in proteoglycan expression and glycosaminoglycan structure

引用

BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS 2017年第9期1861卷 2250-2260页

作者： Henriet, Elodie Jaeger, Sibylle Tran, Christian Bastien, Philippe Michelet, Jean-Francois Minondo, Anne-Marie Formanek, Florian Dalko-Csiba, Maria Lortat-Jacob, Hugues Breton, Lionel Vives, Romain R. Univ Grenoble Alpes CNRS CEA IBS F-38000 Grenoble France LOreal Res & Innovat Aulnay Sous Bois France

Background: Jasmonates are plant hormones that exhibit anti-cancer and anti-inflammatory properties and have therefore raised interest for human health applications. The molecular basis of these activities remains poorly understood, although increasing evidence suggests that a variety of mechanisms may be involved. Recently, we have reported that a jasmonate derivative (JAD) displayed anti-aging effects on human skin by inducing extracellular matrix (ECM) remodeling. Based on this observation, we have investigated here the effects of JAD on proteoglycans and glycosaminoglycan (GAG) polysaccharides, which are major cell-surface/ECM components and are involved in a multitude of biological processes. In parallel, we have examined the ability of JAD to promote growth factor activities and improve skin wound healing. Methods: Proteoglycan expression was analyzed on epidermal primary keratinocytes and reconstituted skin epidermis, using electron/immunofluorescence microscopy, western blotting and flow cytometry. GAG composition was determined by disaccharide analysis. Finally, biological activities of JAD were assessed in cellulo, in FGF-7 induced migration/proliferation assays, as well as in vivo, using a suction blister model performed on 24 healthy volunteers. Results: JAD was found to induce expression of major skin proteoglycans and to induce subtle changes in GAG structure. In parallel, we showed that JAD promoted FGF-7 and improved skin healing by accelerating epithelial repair in vivo. Conclusion: This study highlights JAD as a promising compound for investigating GAG structure-function relationships and for applications in skin cosmetic /corrective strategies.

关键词： Jasmonate Glycosaminoglycan structure-function relationships Reconstructed epidermis Epithelial repair

来源：评论

学校读者我要写书评

暂无评论

Structural basis for enzyme bifunctionality - the case of Gan1D from Geobacillusstearothermophilus

引用

FEBS JOURNAL 2017年第22期284卷 3931-3953页

作者： Lansky, Shifra Zehavi, Arie Belrhali, Hassan Shoham, Yuval Shoham, Gil Hebrew Univ Jerusalem Inst Chem Lab Struct Chem & Biol IL-91904 Jerusalem Israel Technion Israel Inst Technol Dept Biotechnol & Food Engn IL-32000 Haifa Israel European Synchrotron Radiat Facil Grenoble France

6-phospho--glucosidases and 6-phospho--galactosidases are enzymes that hydrolyze the -glycosidic bond between a terminal non-reducing glucose-6-phosphate (Glc6P) or galactose-6-phosphate (Gal6P), respectively, and other organic molecules. Gan1D, a glycoside hydrolase (GH) belonging to the GH1 family, has recently been identified in a newly characterized galactan-utilization gene cluster in the bacterium Geobacillusstearothermophilus T-1. Gan1D has been shown to exhibit bifunctional activity, possessing both 6-phospho--galactosidase and 6-phospho--glucosidase activities. We report herein the complete 3D crystal structure of Gan1D, together with its acid/base catalytic mutant Gan1D-E170Q. The tertiary structure of Gan1D conforms well to the (/)(8) TIM-barrel fold commonly observed in GH enzymes, and its quaternary structure adopts a dimeric assembly, confirmed by gel-filtration and small-angle X-ray scattering results. We present also the structures of Gan1D in complex with the putative substrate cellobiose-6-phosphate (Cell6P) and the degradation products Glc6P and Gal6P. These complexes reveal the specific enzyme-substrate and enzyme-product binding interactions of Gan1D, and the residues involved in its glycone, aglycone, and phosphate binding sites. We show that the different ligands trapped in the active sites adopt different binding modes to the protein, providing a structural basis for the dual galactosidase/glucosidase activity observed for this enzyme. Based on this information, specific mutations were performed on one of the active site residues (W433), shifting the enzyme specificity from dual activity to a significant preference toward 6-phospho--glucosidase activity. These data and their comparison with structural data of related glucosidases and galactosidases are used for a more general discussion on the structure-function relationships in this sub-group of GH1 enzymes. DatabasesAtomic coordinates of Gan1D-wild-type (WT)-P1, Gan1D-WT-C2, Gan1D-E170Q, Ga

关键词： 6-phospho-beta-galactosidase 6-phospho-beta-glucosidase broad specificity galactan utilization negative cooperativity semi-conservative resolution cut-off small-angle X-ray scattering structure-function relationships

来源：评论

学校读者我要写书评

暂无评论

Elucidating the structure-function Relationship of Poly(3,4-theylenedioxythiophene) Films to Advance Electrochemical Measurements

引用

JOURNAL OF PHYSICAL CHEMISTRY C 2016年第37期120卷 21114-21122页

作者： Meier, Adam R. Bahureksa, William A. Heien, Michael L. Univ Arizona Dept Chem & Biochem 1306 East Univ Blvd Tucson AZ 85721 USA

Previous work has demonstrated the utility of poly(3,4-theylenedioxythiophene) (PEDOT) electrodes for electrochemical detection of neurochemicals. Although these electrodes have been implemented successfully, there is minimal data linking redox mechanisms, electron-transfer characteristics, and sensor lifetime to the electrode molecular composition. Common polymer electrodes are made from commercially available PEDOT:polystyrenesulfonate (PEDOT:PSS), which is easily processed but has slow electron transfer kinetics and short electrochemical lifetimes. Here, we describe vapor-phase synthesized PEDOT:tosylate films that have a higher conductance and a much lower apparent capacitance than PEDOT:PSS (99 +/- versus 2390 +/- 30 mu Fcm(2)). Additionally, we show that the electron-transfer kinetics and electrochemical lifetime are both improved. To investigate the chemical causes of these improvements we used ultraviolet visible absorbance and X-ray photoelectron spectroscopy (XPS). We discovered that the high density of PEDOT incorporated into PEDOT:tosylate films coupled with the lack of impurities and replacing the polymeric dopant (PSS) leads to both increased conductance and reduced film capacitance. This is most clearly demonstrated through the doping ratio of 3.80 +/- 0.10 in vapor phase synthesized PEDOT:tosylate versus 0.20 +/- 0.02 in PEDOT:PSS. Furthermore, the electrochemical lifetime of the films is dependent upon the amount of PEDOT present. XPS data was used to elucidate the mode of failure of these electrodes. This begins to illuminate the mechanism of electron transfer at conducting polymers electrodes. Understanding both the characteristics that improve the quality of conducting polymer electrodes and the mechanism of electron transfer therein is a crucial step in the wider adaptation of these materials in biosensor applications.

关键词： electron transfer FAILURE MODES capacitance structure-function relationships Electrodes Electron transfer kinetics Films conducting polymers electrochemical detection Redox processes vapor phases

来源：评论

学校读者我要写书评

暂无评论

Introduction to a Virtual Issue on root traits

引用

NEW PHYTOLOGIST 2017年第1期215卷 5-8页

作者： Norby, Richard J. Iversen, Colleen M. Oak Ridge Natl Lab Environm Sci Div Oak Ridge TN 37830 USA Oak Ridge Natl Lab Climate Change Sci Inst Oak Ridge TN 37830 USA

Link to the Virtual Issue

关键词： fine roots root economics spectrum root traits structure-function relationships terrestrial biosphere models

来源：评论

学校读者我要写书评

暂无评论

Accelerating physical simulations of proteins by leveraging external knowledge

引用

WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017年第5期7卷 e1309页

作者： Perez, Alberto Morrone, Joseph A. Dill, Ken A. IBM TJ Watson Res Ctr 1101 Kitchawan Rd Yorktown Hts NY USA SUNY Stony Brook Laufer Ctr Phys & Quantitat Biol Stony Brook NY 11794 USA SUNY Stony Brook Chem Dept Stony Brook NY 11794 USA SUNY Stony Brook Phys & Astron Dept Stony Brook NY 11794 USA

It is challenging to compute structure-function relationships of proteins using molecular physics. The problem arises from the exponential scaling of the computational searching and sampling of large conformational spaces. This scaling challenge is not met by today's methods, such as Monte Carlo, simulated annealing, genetic algorithms, or molecular dynamics (MD) or its variants such as replica exchange. Such methods of searching for optimal states on complex probabilistic landscapes are referred to more broadly as Explore-and-Exploit (EE), including in contexts such as computational learning, games, industrial planning, and modeling military strategies. Here, we describe a Bayesian method, called MELD, that 'melds' together EE approaches with externally added information that can be vague, combinatoric, noisy, intuitive, heuristic, or from experimental data. MELD is shown to accelerate physical MD simulations when using experimental data to determine protein structures;for predicting protein structures by using heuristic directives;and when predicting binding affinities of proteins from limited information about the binding site. Such Guided EE approaches might also be useful beyond proteins and beyond molecular science. (C) 2017 John Wiley & Sons, Ltd

关键词： Searches structure-function relationships Binding Sites physical simulating Molecular Dynamics physical simulation Heuristics acceleration Experimental data Bayes methods Proteins molecular physics

来源：评论

学校读者我要写书评

暂无评论

Development of next generation adeno-associated viral vectors capable of selective tropism and efficient gene delivery

引用

BIOMATERIALS 2016年第0期80卷 134-145页

作者： Zhang, Chuanling Yao, Tianzhuo Zheng, Yongxiang Li, Zhongjun Zhang, Qiang Zhang, Lihe Zhou, Demin Peking Univ Sch Pharmaceut Sci State Key Lab Nat & Biomimet Drugs Beijing 100191 Peoples R China

Virus-based nanoparticles have shown promise as vehicles for delivering therapeutic genes. However, the rational design of viral vectors that enable selective tropism towards particular types of cells and tissues remains challenging. Here, we explored structural-functional relationships of the adeno-associated virus 2 (AAV2) vector by expanding its genetic code during production. As a proof-of principle, an azide moiety was strategically displayed on the vector capsid as a bioorthogonal chemical reporter. Upon bioorthogonal conjugation of AAV2 with fluorophores and cyclic arginyl-glycylaspartic acid ligands at certain modifiable sites, we characterized in vitro and in vivo AAV2 movement and enhanced tropism selectivity towards integrin-expressing tumor cells. Targeting AAV2 vectors resulted in selective killing of U87 glioblastoma cells and derived xenografts via the herpes simplex virus suicide gene thymidine kinase, with the potency of ganciclovir being increased by 25-fold. Our results demonstrated successful rational modification of AAV2 as a targeting delivery vehicle, establishing a facile platform for precision engineering of virus-based nanoparticles in basic research and therapeutic applications. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Adeno-associated virus Genetic code expansion Unnatural amino acids structure-function relationships Targeted delivery

来源：评论

学校读者我要写书评

暂无评论

Design principles for hydrogen evolution reaction catalyst materials

引用

NANO ENERGY 2016年 29卷 29-36页

作者： Strmcnik, Dusan Lopes, Pietro Papa Genorio, Bostjan Stamenkovic, Vojislav R. Markovic, Nenad M. Argonne Natl Lab Div Mat Sci 9700 S Cass Ave Argonne IL 60439 USA

Design and synthesis of active, stable and cost-effective materials for efficient hydrogen production (hydrogen evolution reaction, HER) is of paramount importance for the successful deployment of hydrogen -based alternative energy technologies. The HER, seemingly one of the simplest electrochemical reactions, has served for decades to bridge the gap between fundamental electrocatalysis and practical catalyst design. However, there are still many open questions that need to be answered before it would be possible to claim that design principles of catalyst materials are fully developed for the efficient hydrogen production. In this review, by summarizing key results for the HER on well-characterized electrochemical interfaces in acidic and alkaline media, we have broadened our understanding of the HER in the whole range of pH by considering three main parameters: the nature of the proton donor (H3O+ in acid and H2O in alkaline), the energy of adsorption of H-ad and OHad, and the presence of spectator species. Simply by considering these three parameters we show that great deal has already been learned and new trends are beginning to emerge, giving some predictive ability with respect to the nature of electrochemical interface and electrocatalytic activity of the HER. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Hydrogen evolution reaction Electrocatalysis pH effect Surface science structure-function relationships

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：