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Protein structure

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https://www.readbyqxmd.com/read/27926995/frozen-but-no-accident-why-the-20-standard-amino-acids-were-selected
#1
REVIEW
Andrew J Doig
The 20 standard amino acids encoded by the Genetic Code were adopted during the RNA World, around 4 billion years ago. This amino acid set could be regarded as a frozen accident, implying that other possible structures could equally well have been chosen to use in proteins. Amino acids were not primarily selected for their ability to support catalysis, since the RNA World already had highly effective cofactors to perform reactions, such as oxidation, reduction and transfer of small molecules. Rather, they were selected to enable the formation of soluble structures with close-packed cores, allowing the presence of ordered binding pockets...
December 7, 2016: FEBS Journal
https://www.readbyqxmd.com/read/27926992/inherited-diseases-caused-by-mutations-in-cathepsin-protease-genes
#2
REVIEW
Stephanie Ketterer, Alejandro Gomez-Auli, Larissa E Hillebrand, Agnese Petrera, Anett Ketscher, Thomas Reinheckel
Lysosomal cathepsins are proteolytic enzymes increasingly recognized as prognostic markers and potential therapeutic targets in a variety of diseases. In those conditions the cathepsins are mostly overexpressed, thereby driving the respective pathogenic processes. Although less known, there are also diseases with a genetic deficiency of cathepsins. In fact, nowadays six out of the fifteen human proteases called "cathepsins" have been linked to inherited syndromes. However, only three of these syndromes are typical lysosomal storage diseases, while the others are apparently caused by defective cleavage of specific protein substrates...
December 7, 2016: FEBS Journal
https://www.readbyqxmd.com/read/27926939/a-bystander-mechanism-explains-the-specific-phenotype-of-a-broadly-expressed-misfolded-protein
#3
Lauren Klabonski, Ji Zha, Lakshana Senthilkumar, Tali Gidalevitz
Misfolded proteins in transgenic models of conformational diseases interfere with proteostasis machinery and compromise the function of many structurally and functionally unrelated metastable proteins. This collateral damage to cellular proteins has been termed 'bystander' mechanism. How a single misfolded protein overwhelms the proteostasis, and how broadly-expressed mutant proteins cause cell type-selective phenotypes in disease are open questions. We tested the gain-of-function mechanism of a R37C folding mutation in an endogenous IGF-like C...
December 2016: PLoS Genetics
https://www.readbyqxmd.com/read/27926928/an-interactome-centered-protein-discovery-approach-reveals-novel-components-involved-in-mitosome-function-and-homeostasis-in-giardia-lamblia
#4
Samuel Rout, Jon Paulin Zumthor, Elisabeth M Schraner, Carmen Faso, Adrian B Hehl
Protozoan parasites of the genus Giardia are highly prevalent globally, and infect a wide range of vertebrate hosts including humans, with proliferation and pathology restricted to the small intestine. This narrow ecological specialization entailed extensive structural and functional adaptations during host-parasite co-evolution. An example is the streamlined mitosomal proteome with iron-sulphur protein maturation as the only biochemical pathway clearly associated with this organelle. Here, we applied techniques in microscopy and protein biochemistry to investigate the mitosomal membrane proteome in association to mitosome homeostasis...
December 2016: PLoS Pathogens
https://www.readbyqxmd.com/read/27926869/robust-asymmetric-localization-of-planar-polarity-proteins-is-associated-with-organization-into-signalosome-like-domains-of-variable-stoichiometry
#5
Helen Strutt, Jessica Gamage, David Strutt
In developing epithelia, the core planar polarity proteins physically interact with each other and localize asymmetrically at opposite cell ends, forming intercellular complexes that link the polarity of neighboring cells. Using quantitative imaging to examine the composition of the core protein complex in vivo, we find that complex composition is unexpectedly plastic. The transmembrane proteins Frizzled and Flamingo form a stoichiometric nucleus in the complex, while the relative levels of the other four core proteins can vary independently...
December 6, 2016: Cell Reports
https://www.readbyqxmd.com/read/27926843/membrane-anchoring-and-ion-entry-dynamics-in-p-type-atpase-copper-transport
#6
Christina Grønberg, Oleg Sitsel, Erik Lindahl, Pontus Gourdon, Magnus Andersson
Cu(+)-specific P-type ATPase membrane protein transporters regulate cellular copper levels. The lack of crystal structures in Cu(+)-binding states has limited our understanding of how ion entry and binding are achieved. Here, we characterize the molecular basis of Cu(+) entry using molecular-dynamics simulations, structural modeling, and in vitro and in vivo functional assays. Protein structural rearrangements resulting in the exposure of positive charges to bulk solvent rather than to lipid phosphates indicate a direct molecular role of the putative docking platform in Cu(+) delivery...
December 6, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27926842/intact-telopeptides-enhance-interactions-between-collagens
#7
Marjan Shayegan, Tuba Altindal, Evan Kiefl, Nancy R Forde
Collagen is the fundamental structural component of a wide range of connective tissues and of the extracellular matrix. It undergoes self-assembly from individual triple-helical proteins into well-ordered fibrils, a process that is key to tissue development and homeostasis, and to processes such as wound healing. Nucleation of this assembly is known to be slowed considerably by pepsin removal of short nonhelical regions that flank collagen's triple helix, known as telopeptides. Using optical tweezers to perform microrheology measurements, we explored the changes in viscoelasticity of solutions of collagen with and without intact telopeptides...
December 6, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27926841/broken-tales-transcription-activator-like-effectors-populate-partly-folded-states
#8
Kathryn Geiger-Schuller, Doug Barrick
Transcription activator-like effector proteins (TALEs) contain large numbers of repeats that bind double-stranded DNA, wrapping around DNA to form a continuous superhelix. Since unbound TALEs retain superhelical structure, it seems likely that DNA binding requires a significant structural distortion or partial unfolding. In this study, we use nearest-neighbor "Ising" analysis of consensus TALE (cTALE) repeat unfolding to quantify intrinsic folding free energies, coupling energies between repeats, and the free energy distribution of partly unfolded states, and to determine how those energies depend on the sequence that determines DNA-specificity (called the "RVD")...
December 6, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27926839/circular-dichroism-spectroscopy-of-collagen-fibrillogenesis-a-new-use-for-an-old-technique
#9
Kathryn E Drzewiecki, Daniel R Grisham, Avanish S Parmar, Vikas Nanda, David I Shreiber
Type-I collagen assembles in a stepwise, hierarchic fashion from the folding of the triple helix to the assembly of fibrils into fibers. The mature assembled fibers are crucial for tissue structure and mechanics, cell interactions, and other functions in vivo. Although triple helix folding can be followed with the use of optical methods such as circular dichroism (CD) spectroscopy, fibrillogenesis is typically measured by alternative methods such as turbidity, rheology, and microscopy. Together, these approaches allow for investigation of the mechanical properties and architectures of collagen-based scaffolds and excised tissues...
December 6, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27926838/high-resolution-mapping-of-a-repeat-protein-folding-free-energy-landscape
#10
Martin J Fossat, Thuy P Dao, Kelly Jenkins, Mariano Dellarole, Yinshan Yang, Scott A McCallum, Angel E Garcia, Doug Barrick, Christian Roumestand, Catherine A Royer
A complete description of the pathways and mechanisms of protein folding requires a detailed structural and energetic characterization of the conformational ensemble along the entire folding reaction coordinate. Simulations can provide this level of insight for small proteins. In contrast, with the exception of hydrogen exchange, which does not monitor folding directly, experimental studies of protein folding have not yielded such structural and energetic detail. NMR can provide residue specific atomic level structural information, but its implementation in protein folding studies using chemical or temperature perturbation is problematic...
December 6, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27926836/probing-small-molecule-binding-to-unfolded-polyprotein-based-on-its-elasticity-and-refolding
#11
Ricksen S Winardhi, Qingnan Tang, Jin Chen, Mingxi Yao, Jie Yan
Unfolded protein, a disordered structure found before folding of newly synthesized protein or after protein denaturation, is a substrate for binding by many cellular factors such as heat-stable proteins, chaperones, and many small molecules. However, it is challenging to directly probe such interactions in physiological solution conditions because proteins are largely in their folded state. In this work we probed small molecule binding to mechanically unfolded polyprotein using sodium dodecyl sulfate (SDS) as an example...
December 6, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27926833/conformational-plasticity-in-the-transsynaptic-neurexin-cerebellin-glutamate-receptor-adhesion-complex
#12
Shouqiang Cheng, Alpay B Seven, Jing Wang, Georgios Skiniotis, Engin Özkan
Synaptic specificity is a defining property of neural networks. In the cerebellum, synapses between parallel fiber neurons and Purkinje cells are specified by the simultaneous interactions of secreted protein cerebellin with pre-synaptic neurexin and post-synaptic delta-type glutamate receptors (GluD). Here, we determined the crystal structures of the trimeric C1q-like domain of rat cerebellin-1, and the first complete ectodomain of a GluD, rat GluD2. Cerebellin binds to the LNS6 domain of α- and β-neurexin-1 through a high-affinity interaction that involves its highly flexible N-terminal domain...
December 6, 2016: Structure
https://www.readbyqxmd.com/read/27926831/ras-association-domain-dimers-bring-proteins-together
#13
Holger Rehmann, Johannes L Bos
In this issue of Structure, Gingras et al. (2016) show that Ras association (RA) domains of the Rap1 and Ras interacting protein Rasip1 can form a dimer in the presence and absence of the small G protein Rap1. This provides an explanation for the observed complex formation in Rap1-mediated signaling.
December 6, 2016: Structure
https://www.readbyqxmd.com/read/27926829/caught-on-camera-intermediates-of-ribosome-recycling
#14
Clarence Ling, Dmitri N Ermolenko
Following termination of protein synthesis, bacterial ribosomes are split into subunits by the joint action of elongation factor G and ribosome recycling factor in the process called ribosome recycling. In this issue of Structure, Fu et al. (2016) describe visualization of transient intermediates of ribosome recycling using time-resolved cryogenic electron microscopy.
December 6, 2016: Structure
https://www.readbyqxmd.com/read/27926736/structure-of-cc-chemokine-receptor-2-with-orthosteric-and-allosteric-antagonists
#15
Yi Zheng, Ling Qin, Natalia V Ortiz Zacarías, Henk de Vries, Gye Won Han, Martin Gustavsson, Marta Dabros, Chunxia Zhao, Robert J Cherney, Percy Carter, Dean Stamos, Ruben Abagyan, Vadim Cherezov, Raymond C Stevens, Adriaan P IJzerman, Laura H Heitman, Andrew Tebben, Irina Kufareva, Tracy M Handel
CC chemokine receptor 2 (CCR2) is one of 19 members of the chemokine receptor subfamily of human class A G-protein-coupled receptors. CCR2 is expressed on monocytes, immature dendritic cells, and T-cell subpopulations, and mediates their migration towards endogenous CC chemokine ligands such as CCL2 (ref. 1). CCR2 and its ligands are implicated in numerous inflammatory and neurodegenerative diseases including atherosclerosis, multiple sclerosis, asthma, neuropathic pain, and diabetic nephropathy, as well as cancer...
December 7, 2016: Nature
https://www.readbyqxmd.com/read/27926732/electric-field-stimulated-protein-mechanics
#16
Doeke R Hekstra, K Ian White, Michael A Socolich, Robert W Henning, Vukica Šrajer, Rama Ranganathan
The internal mechanics of proteins-the coordinated motions of amino acids and the pattern of forces constraining these motions-connects protein structure to function. Here we describe a new method combining the application of strong electric field pulses to protein crystals with time-resolved X-ray crystallography to observe conformational changes in spatial and temporal detail. Using a human PDZ domain (LNX2(PDZ2)) as a model system, we show that protein crystals tolerate electric field pulses strong enough to drive concerted motions on the sub-microsecond timescale...
December 7, 2016: Nature
https://www.readbyqxmd.com/read/27926729/intracellular-allosteric-antagonism-of-the-ccr9-receptor
#17
Christine Oswald, Mathieu Rappas, James Kean, Andrew S Doré, James C Errey, Kirstie Bennett, Francesca Deflorian, John A Christopher, Ali Jazayeri, Jonathan S Mason, Miles Congreve, Robert M Cooke, Fiona H Marshall
Chemokines and their G-protein-coupled receptors play a diverse role in immune defence by controlling the migration, activation and survival of immune cells. They are also involved in viral entry, tumour growth and metastasis and hence are important drug targets in a wide range of diseases. Despite very significant efforts by the pharmaceutical industry to develop drugs, with over 50 small-molecule drugs directed at the family entering clinical development, only two compounds have reached the market: maraviroc (CCR5) for HIV infection and plerixafor (CXCR4) for stem-cell mobilization...
December 7, 2016: Nature
https://www.readbyqxmd.com/read/27925686/slc4a11-three-dimensional-homology-model-rationalizes-corneal-dystrophy-causing-mutations
#18
Katherine E Badior, Kumari Alka, Joseph R Casey
We studied the structural effects of point mutations of a membrane protein that cause genetic disease. SLC4A11 is a membrane transport protein (OH(-) /H(+) /NH3 /H2 O) of basolateral corneal endothelium, whose mutations cause some cases of Congenital Hereditary Endothelial Dystrophy and Fuchs Endothelial Corneal Dystrophy. We created a three-dimensional homology model of SLC4A11 membrane domain, using Band 3 (SLC4A1) crystal structure as template. The homology model was assessed in silico and by analysis of mutants designed on the basis of the model...
December 7, 2016: Human Mutation
https://www.readbyqxmd.com/read/27925594/a-memetic-algorithm-for-3-d-protein-structure-prediction-problem
#19
Leonardo Correa, Bruno Borguesan, Camilo Farfan, Mario Inostroza-Ponta, Marcio Dorn
Memetic Algorithms are population-based metaheuristics intrinsically concerned with exploiting all available knowledge about the problem under study. The incorporation of problem domain knowledge is not an optional mechanism, but a fundamental feature of the Memetic Algorithms. In this paper, we present a Memetic Algorithm to tackle the three-dimensional protein structure prediction problem. The method uses a structured population and incorporates a Simulated Annealing algorithm as a local search strategy, as well as ad-hoc crossover and mutation operators to deal with the problem...
December 2, 2016: IEEE/ACM Transactions on Computational Biology and Bioinformatics
https://www.readbyqxmd.com/read/27925401/dickeya-dadantii-pectic-enzymes-necessary-for-virulence-are-also-responsible-for-activation-of-the-arabidopsis-thaliana-innate-immune-system
#20
Dominique Expert, Oriane Patrit, Vladimir E Shevchik, Claude Perino, Virginie Boucher, Creze Christophe, Estelle Wenes, Mathilde Fagard
Soft-rot diseases of plants attributed to Dickeya dadantii result from lysis of plant cell wall due to pectic enzymes released by the bacterial cell by a type II secretion system (T2SS). A. thaliana can express several lines of defence against this bacterium. We employed bacterial mutants with defective envelope structures or secreted proteins to examine early plant defence reactions. We focused on the production of AtrbohD-dependent ROS, callose deposition and cell death as indicators of these reactions. We observed a significant reduction in ROS and callose formation with a bacterial mutant where genes encoding five pectate lyases (Pels) were disrupted...
December 7, 2016: Molecular Plant Pathology
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