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Structures of membrane protein

Rebba C Boswell-Casteel, Franklin A Hays
Equilibrative nucleoside transporters (ENTs) are polytopic integral membrane proteins that mediate the transport of nucleosides, nucleobases, and therapeutic analogs. The best-characterized ENTs are the human transporters hENT1 and hENT2. However, non-mammalian eukaryotic ENTs have also been studied (e.g., yeast, parasitic protozoa). ENTs are major pharmaceutical targets responsible for modulating the efficacy of more than 30 approved drugs. However, the molecular mechanisms and chemical determinants of ENT-mediated substrate recognition, binding, inhibition, and transport are poorly understood...
October 19, 2016: Nucleosides, Nucleotides & Nucleic Acids
Jinshan Jin, Ying-Hsin Hsieh, Jianmei Cui, Krishna Damera, Chaofeng Dai, Arpana S Chaudhary, Hao Zhang, Hsiuchin Yang, Nannan Cao, Chun Jiang, Martti Vaara, Binghe Wang, Phang C Tai
With the widespread emergence of drug resistance, there is an urgent need to search for new antimicrobials, especially those against Gram-negative bacteria. Along this line, the identification of viable targets is a critical first step. The protein translocase SecA is commonly believed to be an excellent target for the development of broad-spectrum antimicrobials. In recent years, we developed three structural classes of SecA inhibitors that have proven to be very effective against Gram-positive bacteria. However, we have not achieved the same level of success against Gram-negative bacteria, despite the potent inhibition of SecA in enzyme assays by the same inhibitors...
October 18, 2016: ChemMedChem
Jia Shi, Jian-Bo Yu, Wei Liu, Dan Wang, Yuan Zhang, Li-Rong Gong, Shu-An Dong, Da-Quan Liu
Acute respiratory distress syndrome (ARDS) is one of the most devastating complications of sepsis lacking of effective therapy. Mitochondrial dynamics undergoing continuous fusion and fission play a crucial role in mitochondrial structure and function. Fis1, as a small protein located on the outer membrane of mitochondria, has been thought to be an important protein mediated mitochondrial fission. During ARDS, alveolar macrophages suffer from increased oxidative stress and apoptosis, and also accompanied by disrupted mitochondrial dynamics...
October 14, 2016: Experimental Cell Research
Hye Yeon Koh, Hyun Park, Jun Hyuck Lee, Se Jong Han, Young Chang Sohn, Sung Gu Lee
Psychrobacter sp. PAMC 21119, isolated from Antarctic permafrost soil, grows and proliferates at subzero temperatures. However, its major mechanism of cold adaptation regulation remains poorly understood. We investigated the transcriptomic and proteomic responses of this species to cold temperatures by comparing profiles at -5°C and 20°C to understand how extreme microorganisms survive under subzero conditions. We found a total of 2,906 transcripts and 584 differentially expressed genes (≥ 2 fold, p <0...
October 17, 2016: Environmental Microbiology
Jovan Nikolic, Ahmet Civas, Zoé Lama, Cécile Lagaudrière-Gesbert, Danielle Blondel
Stress granules (SGs) are membrane-less dynamic structures consisting of mRNA and protein aggregates that form rapidly in response to a wide range of environmental cellular stresses and viral infections. They act as storage sites for translationally silenced mRNAs under stress conditions. During viral infection, SG formation results in the modulation of innate antiviral immune responses, and several viruses have the ability to either promote or prevent SG assembly. Here, we show that rabies virus (RABV) induces SG formation in infected cells, as revealed by the detection of SG-marker proteins Ras GTPase-activating protein-binding protein 1 (G3BP1), T-cell intracellular antigen 1 (TIA-1) and poly(A)-binding protein (PABP) in the RNA granules formed during viral infection...
October 2016: PLoS Pathogens
Hitomi Hoshino, Makoto Ohta, Makoto Ito, Kenji Uchimura, Yasuhiro Sakai, Takeshi Uehara, Shulin Low, Mana Fukushima, Motohiro Kobayashi
Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver neoplasm, followed by hepatocellular carcinoma. ICC can be further subclassified as (i) perihilar and (ii) peripheral types, the latter histologically resembling small-sized intrahepatic bile ducts, such as interlobular bile ducts, cholangioles/ductules and the canals of Hering. Cholangiolocellular carcinoma (CoCC), now classified by the World Health Organization as a subtype of combined hepatocellular-cholangiocarcinoma, is currently regarded as a subtype of peripheral-type ICC...
October 17, 2016: Laboratory Investigation; a Journal of Technical Methods and Pathology
Sang Joon Won, Dahvid Davda, Kristin J Labby, Sin Ye Hwang, Rachel E Pricer, Jaimeen D Majmudar, Kira A Armacost, Laura A Rodriguez, Christina L Rodriguez, Fei San Chong, Kristopher A Torossian, Jasmine Palakurthi, Edward S Hur, Jennifer L Meagher, Charles L Brooks, Jeanne A Stuckey, Brent R Martin
Post-translational S-palmitoylation directs the trafficking and membrane localization of hundreds of cellular proteins, often involving a coordinated palmitoylation cycle that requires both protein acyl transferases (PATs) and acyl protein thioesterases (APTs) to actively re-distribute S-palmitoylated proteins towards different cellular membrane compartments. This process is necessary for the trafficking and oncogenic signaling of S-palmitoylated Ras isoforms, and potentially other peripheral membrane proteins...
October 17, 2016: ACS Chemical Biology
Alessandro Piai, Qingshan Fu, Jyoti Dev, James Jeiwen Chou
Structural characterization of transmembrane proteins in isotropic bicelles has become an increasingly popular application of solution NMR spectroscopy, as the fast-tumbling bicelles are membrane-like yet can often yield spectral quality comparable to those of detergent micelles. While larger bicelles are closer to the true lipid bilayer, it remains unclear how large the bicelles need to be to allow accurate assessment of protein transmembrane partition in lipid bilayer. Here, we address the above question from the perspective of protein residing in the bicelles, through systematic measurement of protein chemical shift and transmembrane partition at different lipid:detergent ratios (q), ranging from 0...
October 17, 2016: Chemistry: a European Journal
Jorge Bernardino de la Serna, Gerhard J Schütz, Christian Eggeling, Marek Cebecauer
Ever since technologies enabled the characterization of eukaryotic plasma membranes, heterogeneities in the distributions of its constituents were observed. Over the years this led to the proposal of various models describing the plasma membrane organization such as lipid shells, picket-and-fences, lipid rafts, or protein islands, as addressed in numerous publications and reviews. Instead of emphasizing on one model we in this review give a brief overview over current models and highlight how current experimental work in one or the other way do not support the existence of a single overarching model...
2016: Frontiers in Cell and Developmental Biology
Jyoti R Misra, Kenneth D Irvine
The protocadherins Dachsous and Fat initiate a signaling pathway that controls growth and planar cell polarity by regulating the membrane localization of the atypical myosin Dachs. How Dachs is regulated by Fat signaling has remained unclear. Here we identify the vamana gene as playing a crucial role in regulating membrane localization of Dachs and in linking Fat and Dachsous to Dachs regulation. Vamana, an SH3-domain-containing protein, physically associates with and co-localizes with Dachs and promotes its membrane localization...
October 7, 2016: Developmental Cell
Ranjeet Kumar, Candan Ariöz, Yaozong Li, Niklas Bosaeus, Sandra Rocha, Pernilla Wittung-Stafshede
After cellular uptake, Copper (Cu) ions are transferred from the chaperone Atox1 to the Wilson disease protein (ATP7B) for incorporation into Cu-dependent enzymes in the secretory pathway. Human ATP7B is a large multi-domain membrane-spanning protein which, in contrast to homologues in other organisms, has six similar cytoplasmic metal-binding domains (MBDs). The reason for multiple MBDs is proposed to be indirect modulation of enzymatic activity and it is thus intriguing that point mutations in MBDs can promote Wilson disease...
October 15, 2016: Biometals: An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine
Isabelle Le Huërou-Luron, Karima Bouzerzour, Stéphanie Ferret-Bernard, Olivia Ménard, Laurence Le Normand, Cécile Perrier, Cindy Le Bourgot, Julien Jardin, Claire Bourlieu, Thomas Carton, Pascale Le Ruyet, Isabelle Cuinet, Cécile Bonhomme, Didier Dupont
PURPOSE: Although composition of infant formula has been significantly improved during the last decade, major differences with the composition and structure of breast milk still remain and might affect nutrient digestion and gut biology. We hypothesized that the incorporation of dairy fat in infant formulas could modify their physiological impacts by making their composition closer to that of human milk. The effect of milk fat and milk fat globule membrane (MFGM) fragments in infant formulas on gut digestion, mucosal immunity and microbiota composition was evaluated...
October 15, 2016: European Journal of Nutrition
Benjamin W Neuman
Replication of eukaryotic positive-stranded RNA viruses is usually linked to the presence of membrane-associated replicative organelles. The purpose of this review is to discuss the function of proteins responsible for formation of the coronavirus replicative organelle. This will be done by identifying domains that are conserved across the order Nidovirales, and by summarizing what is known about function and structure at the level of protein domains.
October 12, 2016: Antiviral Research
Pil Seok Chae, Kyung Ho Cho, Orquidea Ribeiro, Yang Du, Elena Tikhonova, Jonas Mortensen, Kelsey Markham, Parameswaran Hariharan, Claus Løland, Lan Guan, Brian Kobilka, Bernadette Byrne
Detergents serve as useful tools for membrane protein structural and functional studies. Their amphipathic nature allows detergents to associate with the hydrophobic regions of membrane proteins whilst maintaining the proteins in aqueous solution. However, widely used conventional detergents have major limitations and thus there are major efforts to develop novel agents with improved properties. We prepared mesitylene-cored glucoside amphiphiles (MGAs) with three alkyl chains and compared these agents with previously developed xylene-linked maltoside agents (XMAs) with two alkyl chains and a conventional detergent (DDM)...
October 15, 2016: Chemistry: a European Journal
Moritz Flick, Martin Albrecht, Gezina T M L Oei, Renske Steenstra, Raphaela P Kerindongo, Coert J Zuurbier, Hemal H Patel, Markus W Hollmann, Benedikt Preckel, Nina C Weber
Caveolae, lipid enriched invaginations of the plasma membrane, are epicentres of cellular signal transduction. The structural proteins of caveolae, caveolins, regulate effector pathways in anaesthetic-induced cardioprotection, including the RISK pathway. Helium (He) postconditioning (HePoc) is known to mimic anaesthetic conditioning and to prevent damage from myocardial infarction. We hypothesize that HePoc regulates caveolin-1 and caveolin-3 (Cav-1 and Cav-3) expression in the rat heart and activates the RISK pathway...
October 11, 2016: European Journal of Pharmacology
Z Schultzhaus, T B Johnson, B D Shaw
Cell growth necessitates extensive membrane remodeling events including vesicle fusion or fission, processes that are regulated by coat proteins. The hyphal cells of filamentous fungi concentrate both exocytosis and endocytosis at the apex. This investigation focuses on clathrin in Aspergillus nidulans, with the aim of understanding its role in membrane remodeling in growing hyphae. We examined clathrin heavy chain (ClaH-GFP) which localized to three distinct subcellular structures: late Golgi (trans-Golgi equivalents of filamentous fungi), which are concentrated just behind the hyphal tip but are intermittently present throughout all hyphal cells; the region of concentrated endocytosis just behind the hyphal apex (the "endocytic collar"); and small, rapidly moving puncta that were seen trafficking long distances in nearly all hyphal compartments...
October 14, 2016: Molecular Microbiology
Laura László, Balázs Sarkadi, Tamás Hegedűs
ABCG2/BCRP is a membrane protein, involved in xenobiotic and endobiotic transport in key pharmacological barriers and drug metabolizing organs, in the protection of stem cells, and in multidrug resistance of cancer. Pharmacogenetic studies implicated the role of ABCG2 in response to widely used medicines and anticancer agents, as well as in gout. Its Q141K variant exhibits decreased functional expression thus increased drug accumulation and decreased urate secretion. Still, there has been no reliable molecular model available for this protein, as the published structures of other ABC transporters could not be properly fitted to the ABCG2 topology and experimental data...
2016: PloS One
Gavin Hazell, Thomas Arnold, Robert David Barker, Luke Ashley Clifton, Nina-Juliane Steinke, Cecilia Tognoloni, Karen J Edler
Styrene-alt-Maleic Acid lipid particles (SMALPs) are self-assembled discoidal structures composed of a polymer belt and a segment of lipid bilayer, which are capable of encapsulating membrane proteins directly from the cell membrane. Here we present evidence of the exchange of lipids between such "nanodiscs" and lipid monolayers adsorbed at either solid-liquid or air-liquid interfaces. This behavior has important implications for the potential uses of nanodiscs, including the potential to control lipid composition within nanodiscs containing membrane proteins...
October 14, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Michael Groszmann, Hannah L Osborn, John R Evans
Aquaporins are channel proteins that function to increase the permeability of biological membranes. In plants, aquaporins are encoded by multigene families that have undergone substantial diversification in land plants. The Plasma membrane Intrinsic Proteins (PIPs) subfamily of aquaporins are of particular interest given their potential to improve plant water relations and photosynthesis. Flowering plants have between 7 and 28 PIP genes. Their expression varies with tissue and cell type, through development and in response to a variety of factors, contributing to the dynamic and tissue specific control of permeability...
October 14, 2016: Plant, Cell & Environment
Fang Liu, Shutao Ma
Infections caused by pathogenic bacteria are a major health concern throughout the world. Unfortunately, while resistance to current therapies is spreading rapidly, new antibacterial agents to treat these infections are few in number. Thus, there is a great need to develop novel antibacterial agents with new mechanisms of action. Lipopolysaccharides (LPS) are the main component of the outer membrane of Gram-negative bacteria, serving as a permeability barrier, which protects the bacteria from many antibiotics...
October 13, 2016: Mini Reviews in Medicinal Chemistry
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