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Membrane protein crystalization

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https://www.readbyqxmd.com/read/28650463/type-vi-secretion-tssk-baseplate-protein-exhibits-structural-similarity-with-phage-receptor-binding-proteins-and-evolved-to-bind-the-membrane-complex
#1
Van Son Nguyen, Laureen Logger, Silvia Spinelli, Pierre Legrand, Thi Thanh Huyen Pham, Thi Trang Nhung Trinh, Yassine Cherrak, Abdelrahim Zoued, Aline Desmyter, Eric Durand, Alain Roussel, Christine Kellenberger, Eric Cascales, Christian Cambillau
The type VI secretion system (T6SS) is a multiprotein machine widespread in Gram-negative bacteria that delivers toxins into both eukaryotic and prokaryotic cells. The mechanism of action of the T6SS is comparable to that of contractile myophages. The T6SS builds a tail-like structure made of an inner tube wrapped by a sheath, assembled under an extended conformation. Contraction of the sheath propels the inner tube towards the target cell. The T6SS tail is assembled on a platform-the baseplate-which is functionally similar to bacteriophage baseplates...
June 26, 2017: Nature Microbiology
https://www.readbyqxmd.com/read/28650154/interrogating-detergent-desolvation-of-nanopore-forming-proteins-by-fluorescence-polarization-spectroscopy
#2
Aaron J Wolfe, Yi-Ching Hsueh, Adam R Blanden, Mohammad M Mohammad, Bach Pham, Avinash Kumar Thakur, Stewart N Loh, Min Chen, Liviu Movileanu
Understanding how membrane proteins interact with detergents is of fundamental and practical significance in structural and chemical biology as well as in nanobiotechnology. Current methods for inspecting protein-detergent complex (PDC) interfaces require high concentrations of protein and are of low throughput. Here, we describe a scalable, spectroscopic approach that uses nanomolar protein concentrations in native solutions. This approach, which is based on steady-state fluorescence polarization (FP) spectroscopy, kinetically resolves the dissociation of detergents from membrane proteins and protein unfolding...
June 26, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28648608/structures-of-pgam5-provide-insight-into-active-site-plasticity-and-multimeric-assembly
#3
Apirat Chaikuad, Panagis Filippakopoulos, Sean R Marcsisin, Sarah Picaud, Martin Schröder, Shiori Sekine, Hidenori Ichijo, John R Engen, Kohsuke Takeda, Stefan Knapp
PGAM5 is a mitochondrial membrane protein that functions as an atypical Ser/Thr phosphatase and is a regulator of oxidative stress response, necroptosis, and autophagy. Here we present several crystal structures of PGAM5 including the activating N-terminal regulatory sequences, providing a model for structural plasticity, dimerization of the catalytic domain, and the assembly into an enzymatically active dodecameric form. Oligomeric states observed in structures were supported by hydrogen exchange mass spectrometry, size-exclusion chromatography, and analytical ultracentrifugation experiments in solution...
June 10, 2017: Structure
https://www.readbyqxmd.com/read/28642439/assembly-principles-and-structure-of-a-6-5-mda-bacterial-microcompartment-shell
#4
Markus Sutter, Basil Greber, Clement Aussignargues, Cheryl A Kerfeld
Many bacteria contain primitive organelles composed entirely of protein. These bacterial microcompartments share a common architecture of an enzymatic core encapsulated in a selectively permeable protein shell; prominent examples include the carboxysome for CO2 fixation and catabolic microcompartments found in many pathogenic microbes. The shell sequesters enzymatic reactions from the cytosol, analogous to the lipid-based membrane of eukaryotic organelles. Despite available structural information for single building blocks, the principles of shell assembly have remained elusive...
June 23, 2017: Science
https://www.readbyqxmd.com/read/28641111/structural-insights-into-modulation-of-neurexin-neuroligin-trans-synaptic-adhesion-by-mdga1-neuroligin-2-complex
#5
Jung A Kim, Doyoun Kim, Seoung Youn Won, Kyung Ah Han, Dongseok Park, Eunju Cho, Nayoung Yun, Hyun Joo An, Ji Won Um, Eunjoon Kim, Jie-Oh Lee, Jaewon Ko, Ho Min Kim
Membrane-associated mucin domain-containing glycosylphosphatidylinositol anchor proteins (MDGAs) bind directly to neuroligin-1 (NL1) and neuroligin-2 (NL2), thereby respectively regulating excitatory and inhibitory synapse development. However, the mechanisms by which MDGAs modulate NL activity to specify development of the two synapse types remain unclear. Here, we determined the crystal structures of human NL2/MDGA1 Ig1-3 complex, revealing their stable 2:2 arrangement with three interaction interfaces. Cell-based assays using structure-guided, site-directed MDGA1 mutants showed that all three contact patches were required for the MDGA's negative regulation of NL2-mediated synaptogenic activity...
June 21, 2017: Neuron
https://www.readbyqxmd.com/read/28638403/jaburetox-update-on-a-urease-derived-peptide
#6
REVIEW
Arlete Beatriz Becker-Ritt, Camila Saretta Portugal, Célia Regina Carlini
Urease from Canavalia ensiformis seeds was the first enzyme ever to be crystallized, in 1926. These proteins, found in plants, bacteria and fungi, present different biological properties including catalytic hydrolysis of urea, and also enzyme-independent activities, such as induction of exocytosis, pro-inflammatory effects, neurotoxicity, antifungal and insecticidal properties. Urease is toxic to insects and fungi per se but part of this toxicity relies on an internal peptide (~11 kDa), which is released upon digestion of the protein by insect enzymes...
2017: Journal of Venomous Animals and Toxins Including Tropical Diseases
https://www.readbyqxmd.com/read/28638321/membrane-guanylate-cyclase-catalytic-subdomain-structure-and-linkage-with-calcium-sensors-and-bicarbonate
#7
Sarangan Ravichandran, Teresa Duda, Alexandre Pertzev, Rameshwar K Sharma
Membrane guanylate cyclase (MGC) is a ubiquitous multi-switching cyclic GMP generating signaling machine linked with countless physiological processes. In mammals it is encoded by seven distinct homologous genes. It is a single transmembrane spanning multi-modular protein; composed of integrated blocks and existing in homo-dimeric form. Its core catalytic domain (CCD) module is a common transduction center where all incoming signals are translated into the production of cyclic GMP, a cellular signal second messenger...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28638135/temperature-dependence-of-protein-water-interactions-in-a-gated-yeast-aquaporin
#8
Camilo Aponte-Santamaría, Gerhard Fischer, Petra Båth, Richard Neutze, Bert L de Groot
Regulation of aquaporins is a key process of living organisms to counteract sudden osmotic changes. Aqy1, which is a water transporting aquaporin of the yeast Pichia pastoris, is suggested to be gated by chemo-mechanical stimuli as a protective regulatory-response against rapid freezing. Here, we tested the influence of temperature by determining the X-ray structure of Aqy1 at room temperature (RT) at 1.3 Å resolution, and by exploring the structural dynamics of Aqy1 during freezing through molecular dynamics simulations...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28636907/epr-spectroscopy-targets-structural-changes-in-the-e-%C3%A2-coli-membrane-fusion-cusb-upon-cu-i-binding
#9
Aviv Meir, Ahmad Abdelhai, Yoni Moskovitz, Sharon Ruthstein
Bacterial cells have developed sophisticated systems to deal with the toxicity of metal ions. Escherichia coli CusCFBA is a complex efflux system, responsible for transferring Cu(I) and Ag(I) ions; this system, located in the periplasm, involves four proteins, CusA, CusB, CusC, and CusF. CusA, CusB, and CusC are connected to one another in an oligomerization ratio of 3:6:3 CusA/CusB/CusC to form the CusCBA periplasm membrane transporter. CusB is an adaptor protein that connects the two membrane proteins CusA (inner membrane) and CusC (outer membrane)...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636601/crystal-structure-of-the-potassium-importing-kdpfabc-membrane-complex
#10
Ching-Shin Huang, Bjørn Panyella Pedersen, David L Stokes
Cellular potassium import systems play a fundamental role in osmoregulation, pH homeostasis and membrane potential in all domains of life. In bacteria, the kdp operon encodes a four-subunit potassium pump that maintains intracellular homeostasis, cell shape and turgor under conditions in which potassium is limiting. This membrane complex, called KdpFABC, has one channel-like subunit (KdpA) belonging to the superfamily of potassium transporters and another pump-like subunit (KdpB) belonging to the superfamily of P-type ATPases...
June 21, 2017: Nature
https://www.readbyqxmd.com/read/28635292/assembly-morphology-diffusivity-and-indentation-of-hydrogel-supported-lipid-bilayers
#11
Tooba Shoaib, Prathima Chandra Nalam, Yichen He, Yuting Chen, Rosa M Espinosa-Marzal
Recognizing the limitations of solid-supported lipid bilayers to reproduce the behavior of cell membranes, including bendability, transmembrane protein inclusion and virus entry, this study describes a novel biomimetic system for cell membranes with the potential to overcome these and other limitations. The developed strategy utilizes a hydrogel with tunable mechanical behavior that resembles those of living cells as the soft support for the phospholipid bilayer, while a polyelectrolyte multilayer film serves as an intermediate layer to facilitate the self-assembly of the lipid bilayer on the soft cushion...
June 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28634303/structural-characterization-of-the-rabphilin-3a-snap25-interaction
#12
Cristina Ferrer-Orta, María Dolores Pérez-Sánchez, Teresa Coronado-Parra, Cristina Silva, David López-Martínez, Jesús Baltanás-Copado, Juan Carmelo Gómez-Fernández, Senena Corbalán-García, Núria Verdaguer
Membrane fusion is essential in a myriad of eukaryotic cell biological processes, including the synaptic transmission. Rabphilin-3A is a membrane trafficking protein involved in the calcium-dependent regulation of secretory vesicle exocytosis in neurons and neuroendocrine cells, but the underlying mechanism remains poorly understood. Here, we report the crystal structures and biochemical analyses of Rabphilin-3A C2B-SNAP25 and C2B-phosphatidylinositol 4,5-bisphosphate (PIP2) complexes, revealing how Rabphilin-3A C2 domains operate in cooperation with PIP2/Ca(2+) and SNAP25 to bind the plasma membrane, adopting a conformation compatible to interact with the complete SNARE complex...
June 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28623699/the-effect-of-the-protein-corona-on-the-interaction-between-nanoparticles-and-lipid-bilayers
#13
Desirè Di Silvio, Marco Maccarini, Roger Parker, Alan Mackie, Giovanna Fragneto, Francesca Baldelli Bombelli
HYPOTHESIS: It is known that nanoparticles (NPs) in a biological fluid are immediately coated by a protein corona (PC), composed of a hard (strongly bounded) and a soft (loosely associated) layers, which represents the real nano-interface interacting with the cellular membrane in vivo. In this regard, supported lipid bilayers (SLB) have extensively been used as relevant model systems for elucidating the interaction between biomembranes and NPs. Herein we show how the presence of a PC on the NP surface changes the interaction between NPs and lipid bilayers with particular care on the effects induced by the NPs on the bilayer structure...
May 29, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28621666/9%C3%A3-structure-of-the-copi-coat-reveals-that-the-arf1-gtpase-occupies-two-contrasting-molecular-environments
#14
Svetlana O Dodonova, Patrick Aderhold, Juergen Kopp, Iva Ganeva, Simone Röhling, Wim J H Hagen, Irmgard Sinning, Felix Wieland, John A G Briggs
COPI coated vesicles mediate trafficking within the Golgi apparatus and between the Golgi and the endoplasmic reticulum. Assembly of a COPI coated vesicle is initiated by the small GTPase Arf1 that recruits the coatomer complex to the membrane, triggering polymerization and budding. The vesicle uncoats before fusion with a target membrane. Coat components are structurally conserved between COPI and clathrin/adaptor proteins. Using cryo-electron tomography and subtomogram averaging, we determined the structure of the COPI coat assembled on membranes in vitro at 9 Å resolution...
June 16, 2017: ELife
https://www.readbyqxmd.com/read/28620035/molecular-interactions-shaping-the-tetraspanin-web
#15
REVIEW
Sjoerd J van Deventer, Vera-Marie E Dunlock, Annemiek B van Spriel
To facilitate the myriad of different (signaling) processes that take place at the plasma membrane, cells depend on a high degree of membrane protein organization. Important mediators of this organization are tetraspanin proteins. Tetraspanins interact laterally among themselves and with partner proteins to control the spatial organization of membrane proteins in large networks called the tetraspanin web. The molecular interactions underlying the formation of the tetraspanin web were hitherto mainly described based on their resistance to different detergents, a classification which does not necessarily correlate with functionality in the living cell...
June 15, 2017: Biochemical Society Transactions
https://www.readbyqxmd.com/read/28618364/amyloid-like-protein-nanofibrous-membranes-as-a-sensing-layer-infrastructure-for-the-design-of-mass-sensitive-biosensors
#16
Gözde Kabay, Gizem Kaleli Can, Mehmet Mutlu
Quartz crystal microbalances (QCMs) have been used in the literature for mass sensitive biosensor applications. However, their performance, reliability and stability have been limited by the chemical treatment steps required for the functionalization and activation of the QCM surface, prior to antibody immobilization. Specifically, these steps cause increased film thickness, which diminishes performance by mass overload, and create a harsh environment, which reduces biological activity. In this work, we eliminated this chemical step by introducing a sensing layer modification using electrospun amyloid like-bovine serum albumin (AL-BSA) nanofibers on QCM surfaces...
June 10, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28617850/molecular-determinants-for-the-thermodynamic-and-functional-divergence-of-uniporter-glut1-and-proton-symporter-xyle
#17
Meng Ke, Yafei Yuan, Xin Jiang, Nieng Yan, Haipeng Gong
GLUT1 facilitates the down-gradient translocation of D-glucose across cell membrane in mammals. XylE, an Escherichia coli homolog of GLUT1, utilizes proton gradient as an energy source to drive uphill D-xylose transport. Previous studies of XylE and GLUT1 suggest that the variation between an acidic residue (Asp27 in XylE) and a neutral one (Asn29 in GLUT1) is a key element for their mechanistic divergence. In this work, we combined computational and biochemical approaches to investigate the mechanism of proton coupling by XylE and the functional divergence between GLUT1 and XylE...
June 15, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28608415/crystal-structural-characterization-reveals-novel-oligomeric-interactions-of-human-voltage-dependent-anion-channel-1
#18
Toshiaki Hosaka, Masateru Okazaki, Tomomi Kimura-Someya, Yoshiko Ishizuka-Katsura, Kaori Ito, Shigeyuki Yokoyama, Kosuke Dodo, Mikiko Sodeoka, Mikako Shirouzu
Voltage-dependent anion channel 1 (VDAC1), which is located in the outer mitochondrial membrane, plays important roles in various cellular processes. For example, oligomerization of VDAC1 is involved in the release of cytochrome c to the cytoplasm, leading to apoptosis. However, it is unknown how VDAC1 oligomerization occurs in the membrane. In the present study, we determined high-resolution crystal structures of oligomeric human VDAC1 (hVDAC1) prepared by using an Escherichia coli cell-free protein synthesis system, which avoided the need for denaturation and refolding of the protein...
June 12, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28607049/crystal-structures-and-atomic-model-of-nadph-oxidase
#19
Francesca Magnani, Simone Nenci, Elisa Millana Fananas, Marta Ceccon, Elvira Romero, Marco W Fraaije, Andrea Mattevi
NADPH oxidases (NOXs) are the only enzymes exclusively dedicated to reactive oxygen species (ROS) generation. Dysregulation of these polytopic membrane proteins impacts the redox signaling cascades that control cell proliferation and death. We describe the atomic crystal structures of the catalytic flavin adenine dinucleotide (FAD)- and heme-binding domains of Cylindrospermum stagnale NOX5. The two domains form the core subunit that is common to all seven members of the NOX family. The domain structures were then docked in silico to provide a generic model for the NOX family...
June 12, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28605828/crystal-structures-of-claudins-insights-into-their-intermolecular-interactions
#20
REVIEW
Hiroshi Suzuki, Kazutoshi Tani, Yoshinori Fujiyoshi
Claudins are four-transmembrane proteins that constitute the backbone of tight junction strands via self-polymerization in the apicolateral membranes of epithelial cells. Together with their cell-cell adhesion function, claudin proteins form the paracellular barrier and/or channels through epithelial cell sheets whose permeability is primarily dependent on the claudin subtype. Recently determined crystal structures of several claudins revealed the unique claudin fold of four transmembrane helices in a left-handed helical bundle with an extracellular β-sheet domain...
June 2017: Annals of the New York Academy of Sciences
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