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Structures of membrane protein

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https://www.readbyqxmd.com/read/28103440/carbon-nanotubes-mediate-fusion-of-lipid-vesicles
#1
Ramachandra Moorthy Bhaskara, Stephanie M Linker, Martin Vögele, Juergen Koefinger, Gerhard Hummer
The fusion of lipid membranes is opposed by high energetic barriers. In living organisms, complex protein machineries carry out this biologically essential process. Here we show that membrane-spanning carbon nanotubes (CNTs) can trigger spontaneous fusion of small lipid vesicles. In coarse-grained molecular dynamics simulations, we find that a CNT bridging between two vesicles locally perturbs their lipid structure. Their outer leaflets merge as the CNT pulls lipids out of the membranes, creating an hourglass-shaped fusion intermediate with still intact inner leaflets...
January 19, 2017: ACS Nano
https://www.readbyqxmd.com/read/28103282/two-novel-vesicle-inducing-proteins-in-plastids-1-genes-cloned-and-characterized-in-triticum-urartu
#2
Fei Gao, Bo Chen, Juan Jiao, Lijia Jia, Cuimin Liu
Vesicle-inducing protein in plastids 1 (Vipp1) is thought to play an important role both in thylakoid biogenesis and chloroplast envelope maintenance during stress. Vipp1 is conserved in photosynthetic organisms and forms a high homo-oligomer complex structure that may help sustain the membrane integrity of chloroplasts. This study cloned two novel VIPP1 genes from Triticum urartu and named them TuVipp1 and TuVipp2. Both proteins shared high identity with the homologous proteins AtVipp1 and CrVipp1. TuVipp1 and TuVipp2 were expressed in various organs of common wheat, and both genes were induced by light and various stress treatments...
2017: PloS One
https://www.readbyqxmd.com/read/28103010/a-fluorescent-hsp90-probe-demonstrates-the-unique-association-between-extracellular-hsp90-and-malignancy-in-vivo
#3
Lauren B Crowe, Philip F Hughes, David A Alcorta, Takuya Osada, Aaron P Smith, Juliane Totzke, David R Loiselle, Isaac D Lutz, Madhusudhana Gargesha, Debasish Roy, Jose Roques, David Darr, H Kim Lyerly, Neil L Spector, Timothy Aj Haystead
Extracellular expression of heat shock protein 90 (eHsp90) by tumor cells is correlated with malignancy. Development of small molecule probes that can detect eHsp90 in vivo may therefore have utility in the early detection of malignancy. We synthesized a cell impermeable far-red fluorophore-tagged Hsp90 inhibitor to target eHsp90 in vivo. High resolution confocal and lattice light sheet microscopy show that probe-bound eHsp90 accumulates in punctate structures on the plasma membrane of breast tumor cells and is actively internalized...
January 19, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28102396/zinc-sparks-induce-physiochemical-changes-in-the-egg-zona-pellucida-that-prevent-polyspermy
#4
Emily L Que, Francesca E Duncan, Amanda R Bayer, Steven J Philips, Eric W Roth, Reiner Bleher, Sophie C Gleber, Stefan Vogt, Teresa K Woodruff, Thomas V O'Halloran
During fertilization or chemically-induced egg activation, the mouse egg releases billions of zinc atoms in brief bursts known as 'zinc sparks.' The zona pellucida (ZP), a glycoprotein matrix surrounding the egg, is the first structure zinc ions encounter as they diffuse away from the plasma membrane. Following fertilization, the ZP undergoes changes described as 'hardening', which prevent multiple sperm from fertilizing the egg and thereby establish a block to polyspermy. A major event in zona hardening is cleavage of ZP2 proteins by ovastacin; however, the overall physiochemical changes contributing to zona hardening are not well understood...
January 19, 2017: Integrative Biology: Quantitative Biosciences From Nano to Macro
https://www.readbyqxmd.com/read/28102201/direct-pip2-binding-mediates-stable-oligomer-formation-of-the-serotonin-transporter
#5
Andreas Anderluh, Tina Hofmaier, Enrico Klotzsch, Oliver Kudlacek, Thomas Stockner, Harald H Sitte, Gerhard J Schütz
The human serotonin transporter (hSERT) mediates uptake of serotonin from the synaptic cleft and thereby terminates serotonergic signalling. We have previously found by single-molecule microscopy that SERT forms stable higher-order oligomers of differing stoichiometry at the plasma membrane of living cells. Here, we report that SERT oligomer assembly at the endoplasmic reticulum (ER) membrane follows a dynamic equilibration process, characterized by rapid exchange of subunits between different oligomers, and by a concentration dependence of the degree of oligomerization...
January 19, 2017: Nature Communications
https://www.readbyqxmd.com/read/28102001/evaluation-of-the-hybrid-resolution-pace-model-for-the-study-of-folding-insertion-and-pore-formation-of-membrane-associated-peptides
#6
Michael D Ward, Shivangi Nangia, Eric R May
The PACE force field presents an attractive model for conducting molecular dynamics simulations of membrane-protein systems. PACE is a hybrid model, in which lipids and solvents are coarse-grained consistent with the MARTINI mapping, while proteins are described by a united atom model. However, given PACE is linked to MARTINI, which is widely used to study membranes, the behavior of proteins interacting with membranes has only been limitedly examined in PACE. In this study, PACE is used to examine the behavior of several peptides in membrane environments, namely WALP peptides, melittin and influenza hemagglutinin fusion peptide (HAfp)...
January 19, 2017: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/28101868/dystrophin-and-spectrin-two-highly-dissimilar-sisters-of-the-same-family
#7
Olivier Delalande, Aleksander Czogalla, Jean-François Hubert, Aleksander Sikorski, Elisabeth Le Rumeur
Dystrophin and Spectrin are two proteins essential for the organization of the cytoskeleton and for the stabilization of membrane cells. The comparison of these two sister proteins, and with the dystrophin homologue utrophin, enables us to emphasise that, despite a similar topology with common subdomains and a common structural basis of a three-helix coiled-coil, they show a large range of dissimilarities in terms of genetics, cell expression and higher level structural organisation. Interactions with cellular partners, including proteins and membrane phospholipids, also show both strikingly similar and very different behaviours...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28100844/phospholipids-and-products-of-their-hydrolysis-as-dietary-preventive-factors-for-civilization-diseases
#8
Karol Parchem, Agnieszka Bartoszek
The results of numerous epidemiological studies indicate that phospholipids play an important role in the prevention of chronic diseases faced by contemporary society. Firstly, these compounds are responsible for the proper functioning of cell membranes, by ensuring liquidity and permeability, which is pivotal for normal activity of membrane proteins, including receptors. These mechanisms are at the core of prevention of cancer, autoimmune or neurological disorders. Secondly, structure and properties of phospholipids cause that they are highly available source of biologically active fatty acids...
December 31, 2016: Postȩpy Higieny i Medycyny Doświadczalnej
https://www.readbyqxmd.com/read/28100784/mitochondrial-o-glcnac-transferase-mogt-regulates-mitochondrial-structure-function-and-survival-in-hela-cells
#9
Juliana L Sacoman, Raul Y Dagda, Amanda R Burnham-Marusich, Ruben K Dagda, Patricia M Berninsone
O-linked N-acetylglucosamine transferase (OGT) catalyzes O-GlcNAcylation of target proteins and regulates numerous biological processes. OGT is encoded by a single gene that yields nucleocytosolic and mitochondrial isoforms. To date, the role of the mitochondrial isoform of OGT (mOGT) remains largely unknown. Using high-throughput proteomics, we identified 84 candidate mitochondrial glycoproteins, of which 44 are novel. Notably, two of the candidate glycoproteins identified (cytochrome oxidase 2 (COX2) and NADH: ubiquinone oxidoreductase core subunit 4 (MT-ND4)) are encoded by mitochondrial DNA...
January 18, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28100664/rab1-interacts-with-golph3-and-controls-golgi-structure-and-contractile-ring-constriction-during-cytokinesis-in-drosophila-melanogaster
#10
Stefano Sechi, Anna Frappaolo, Roberta Fraschini, Luisa Capalbo, Marco Gottardo, Giorgio Belloni, David M Glover, Alan Wainman, Maria Grazia Giansanti
Cytokinesis requires a tight coordination between actomyosin ring constriction and new membrane addition along the ingressing cleavage furrow. However, the molecular mechanisms underlying vesicle trafficking to the equatorial site and how this process is coupled with the dynamics of the contractile apparatus are poorly defined. Here we provide evidence for the requirement of Rab1 during cleavage furrow ingression in cytokinesis. We demonstrate that the gene omelette (omt) encodes the Drosophila orthologue of human Rab1 and is required for successful cytokinesis in both mitotic and meiotic dividing cells of Drosophila melanogaster We show that Rab1 protein colocalizes with the conserved oligomeric Golgi (COG) complex Cog7 subunit and the phosphatidylinositol 4-phosphate effector GOLPH3 at the Golgi stacks...
January 2017: Open Biology
https://www.readbyqxmd.com/read/28100638/retromer-driven-membrane-tubulation-separates-endosomal-recycling-from-rab7-ypt7-dependent-fusion
#11
Latha Kallur Purushothaman, Henning Arlt, Anne Kuhlee, Stefan Raunser, Christian Ungermann
Endosomes are the major protein sorting hubs of the endocytic pathway. They sort proteins destined for degradation into internal vesicles, while in parallel recycling receptors via tubular carriers back to the Golgi. Tubule formation depends on the Rab7/Ypt7-interacting retromer complex, consisting of the sorting nexin dimer (SNX-BAR) and the trimeric cargo selection complex (CSC). Fusion of mature endosomes with the lysosome-like vacuole also requires Rab7/Ypt7. Here, we now solved a major problem in understanding this dual function of endosomal Rab7/Ypt7 using a fully reconstituted system, including purified, full-length yeast SNX-BAR and CSC, whose overall structure we present...
January 18, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28100636/centriole-splitting-caused-by-loss-of-the-centrosomal-linker-protein-c-nap1-reduces-centriolar-satellite-density-and-impedes-centrosome-amplification
#12
Anne-Marie Flanagan, Elena Stavenschi, Shivakumar Basavaraju, David Gaboriau, David A Hoey, Ciaran G Morrison
Duplication of the centrosomes is a tightly regulated process. Abnormal centrosome numbers can impair cell division and cause changes in how cells migrate. Duplicated centrosomes are held together by a proteinaceous linker made up of rootletin filaments anchored to the centrioles by C-NAP1. This linker is removed in a NEK2A kinase-dependent manner as mitosis begins. To explore C-NAP1 activities in regulating centrosome activities, we used genome editing to ablate it. C-NAP1 null cells were viable and had an increased frequency of premature centriole separation, accompanied by reduced density of the centriolar satellites, with re-expression of C-NAP1 rescuing both these phenotypes...
January 18, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28100609/sterol-binding-by-the-tombusviral-replication-proteins-is-essential-for-replication-in-yeast-and-plants
#13
Kai Xu, Peter D Nagy
: Membranous structures derived from various organelles are important for replication of plus-stranded RNA viruses. Although the important roles of co-opted host proteins in RNA virus replication have been appreciated for a decade, the equally important functions of cellular lipids in virus replication are gaining full attention only recently. Previous works with Tomato bushy stunt tombusvirus (TBSV) in model host yeast have revealed essential roles for phosphatidylethanolamine and sterols in viral replication...
January 18, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28100051/basement-membrane-mimics-of-biofunctionalized-nanofibers-for-a-bipolar-cultured-human-primary-alveolar-capillary-barrier-model
#14
Akihiro Nishiguchi, Smriti Singh, Matthias Wessling, Charles James Kirkpatrick, Martin Moeller
In vitro reconstruction of an alveolar barrier for modeling normal lung functions and pathological events serve as reproducible, high-throughput pharmaceutical platforms for drug discovery, diagnosis, and regenerative medicine. Despite much effort, the reconstruction of organ-level alveolar barrier functions has failed due to the lack of structural similarity to the natural basement membrane, functionalization with specific ligands for alveolar cell function, the use of primary cells and biodegradability. Here we report a bipolar cultured alveolar-capillary barrier model of human primary cells supported by a basement membrane mimics of fully-synthetic bifunctional nanofibers...
January 18, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28099513/the-tetraspanin-associated-uroplakins-family-upk2-3-is-evolutionarily-related-to-ptprq-a-phosphotyrosine-phosphatase-receptor
#15
Javier U Chicote, Rob DeSalle, José Segarra, Tung-Tien Sun, Antonio García-España
Uroplakins are a widespread group of vertebrate integral membrane proteins that belong to two different families: UPK1a and UPK1b belong to the large tetraspanin (TSPAN) gene family, and UPK3a, UPK3b, UPK3c, UPK3d, UPK2a and UPK2b form a family of their own, the UPK2/3 tetraspanin-associated family. In a previous study, we reported that uroplakins first appeared in vertebrates, and that uroplakin tetraspanins (UPK1a and UPK1b) should have originated by duplication of an ancestor tetraspanin gene. However, the evolutionary origin of the UPK2/3 family remains unclear...
2017: PloS One
https://www.readbyqxmd.com/read/28098806/antibacterial-activities-and-possible-modes-of-action-of-acacia-nilotica-l-del-against-multidrug-resistant-escherichia-coli-and-salmonella
#16
Muhammad Bilal Sadiq, Joel Tarning, Tay Zar Aye Cho, Anil Kumar Anal
Medicinal plants are frequently used for the treatment of various infectious diseases. The objective of this study was to evaluate the antibacterial activity and mode of action of Acacia nilotica and the antibiogram patterns of foodborne and clinical strains of Escherichia coli and Salmonella. The mechanism of action of acacia extracts against E. coli and Salmonella was elucidated by observing morphological damages including cell integrity and cell membrane permeability, as well as changes in cell structures and growth patterns in kill-time experiments...
January 14, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28098764/iqgap1-in-podosomes-invadosomes-is-involved-in-the-progression-of-glioblastoma-multiforme-depending-on-the-tumor-status
#17
Deborah Rotoli, Natalia Dolores Pérez-Rodríguez, Manuel Morales, María Del Carmen Maeso, Julio Ávila, Ali Mobasheri, Pablo Martín-Vasallo
Glioblastoma multiforme (GBM) is the most frequent and aggressive primary brain tumor. GBM is formed by a very heterogeneous astrocyte population, neurons, neovascularization and infiltrating myeloid cells (microglia and monocyte derived macrophages). The IQGAP1 scaffold protein interacts with components of the cytoskeleton, cell adhesion molecules, and several signaling molecules to regulate cell morphology and motility, cell cycle and other cellular functions. IQGAP1 overexpression and delocalization has been observed in several tumors, suggesting a role for this protein in cell proliferation, transformation and invasion...
January 13, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28098449/targeting-type-2-diabetes-with-c-glucosyl-dihydrochalcones-as-selective-sodium-glucose-co-transporter-2-sglt2-inhibitors-synthesis-and-biological-evaluation
#18
Ana R Jesus, Diogo Vila-Viçosa, Miguel Machuqueiro, Ana P Marques, Timothy M Dore, Amélia P Rauter
Inhibiting glucose reabsorption by sodium glucose co-transporter proteins (SGLTs) in the kidneys is a relatively new strategy for treating type 2 diabetes. Selective inhibition of SGLT2 over SGLT1 is critical for minimizing adverse side effects associated with SGLT1 inhibition. A library of C-glucosyl dihydrochalcones and their dihydrochalcone and chalcone precursors was synthesized and tested as SGLT1/SGLT2 inhibitors using a cell-based fluorescence assay of glucose uptake. The most potent inhibitors of SGLT2 (IC50 = 9-23 nM) were considerably weaker inhibitors of SGLT1 (IC50 = 10-19 μM)...
January 18, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28098232/crystal-structure-of-sec10-a-subunit-of-the-exocyst-complex
#19
Jianxing Chen, Atsushi Yamagata, Keiko Kubota, Yusuke Sato, Sakurako Goto-Ito, Shuya Fukai
The exocyst complex is a heterooctameric protein complex composed of Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70 and Exo84. This complex plays an essential role in trafficking secretory vesicles to the plasma membrane through its interaction with phosphatidylinositol 4,5-bisphosphate and small GTPases. To date, the near-full-length structural information of each subunit has been limited to Exo70, although the C-terminal half structures of Sec6, Sec15 and Exo84 and the structures of the small GTPase-binding domains of Sec3, Sec5 and Exo84 have been reported...
January 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28097745/immature-core-protein-of-hepatitis-c-virus-induces-an-unfolded-protein-response-through-inhibition-of-erad-l-in-a-yeast-model-system
#20
Shota Takahashi, Naoko Sato, Junichi Kikuchi, Hideaki Kakinuma, Jun Okawa, Yukiko Masuyama, Singo Iwasa, Hayato Irokawa, Gi-Wook Hwang, Akira Naganuma, Michinori Kohara, Shusuke Kuge
The structural protein Core of hepatitis C virus (HCV), a cytosolic protein, induces endoplasmic reticulum (ER) stress and unfolded protein response (UPR) in hepatocytes, and is responsible for the pathogenesis of persistent HCV infection. Using yeast as a model system, we evaluated mechanisms underlying Core-induced interference of ER homeostasis and UPR, and found that UPR is induced by the immature Core (aa 1-191, Core191) but not by the mature Core (aa 1-177, Core177). Interestingly, Core191 inhibits both ERAD-L, a degradation system responsible for misfolded/unfolded proteins in the ER lumen, and ERAD-M, a degradation system responsible for proteins carrying a misfolded/unfolded region in the ER membrane...
January 18, 2017: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
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