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Protein dynamic

Aleksandar Antanasijevic, Nicholas J Hafeman, Smanla Tundup, Carolyn Kingsley, Rama K Mishra, Lijun Rong, Balaji Manicassamy, Duncan Wardrop, Michael Caffrey
The viral envelope protein hemagglutinin (HA) plays a critical role in influenza entry and thus is an attractive target for novel therapeutics. The small molecule tert-butylhydroquinone (TBHQ) has previously been shown to bind to HA and inhibit HA-mediated entry with low micromolar potency. However, enthusiasm for the use of TBHQ has diminished due to the compound's antioxidant properties. In this work we show that the antioxidant properties of TBHQ are not responsible for the inhibition of HA-mediated entry...
September 9, 2016: ACS Infectious Diseases
Karan Kapoor, Michael R Duff, Amit Upadhyay, Joel C Bucci, Arnold M Saxton, Robert J Hinde, Elizabeth E Howell, Jerome Yves Baudry
The dynamics of anion-quadrupole (or anion-) interactions formed between negatively charged (Asp/Glu) and aromatic (Phe) side chains are for the first time computationally characterized in RmlC (PDB: 1EP0), a homodimeric epimerase. Empirical force field-based molecular dynamics simulations predict anion-quadrupole pairs and triplets (anion-anion-anion--) are formed by the protein during the simulated trajectory which suggests that the anion-quadrupole interactions may provide a significant contribution to the overall stability of the protein, with an average of -1...
October 18, 2016: Biochemistry
Jack R Staunton, Wilfred Vieira, King Leung Fung, Ross Lake, Alexus Devine, Kandice Tanner
One of the hallmarks of the malignant transformation of epithelial tissue is the modulation of stromal components of the microenvironment. In particular, aberrant extracellular matrix (ECM) remodeling and stiffening enhances tumor growth and survival and promotes metastasis. Type I collagen is one of the major ECM components. It serves as a scaffold protein in the stroma contributing to the tissue's mechanical properties, imparting tensile strength and rigidity to tissues such as those of the skin, tendons, and lungs...
September 2016: Cellular and Molecular Bioengineering
Dirk Fahrenkamp, Jinyu Li, Sabrina Ernst, Hildegard Schmitz-Van de Leur, Nicolas Chatain, Andrea Küster, Steffen Koschmieder, Bernhard Lüscher, Giulia Rossetti, Gerhard Müller-Newen
STAT5 is an essential transcription factor in hematopoiesis, which is activated through tyrosine phosphorylation in response to cytokine stimulation. Constitutive activation of STAT5 is a hallmark of myeloid and lymphoblastic leukemia. Using homology modeling and molecular dynamics simulations, a model of the STAT5 phosphotyrosine-SH2 domain interface was generated providing first structural information on the activated STAT5 dimer including a sequence, for which no structural information is available for any of the STAT proteins...
October 18, 2016: Scientific Reports
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
Qingqing Liu, Tao Tao, Fang Liu, Runzhou Ni, Cuihua Lu, Aiguo Shen
As an essential post-translational modification, O-GlcNAcylation has been thought to be able to modulate various nuclear and cytoplasmic proteins and is emerging as a key regulator of multiple biological processes, such as transcription, cell growth, signal transduction, and cell motility. Recently, authoritative glycomics analyses have reported extensive crosstalk between O-GlcNAcylation and phosphorylation, which always dynamically interplay with each other and regulate signaling, transcription, and other cellular processes...
October 14, 2016: Experimental Cell Research
Smita Gupta, Sunita Yadav, Venkatesan Suryanarayanan, Sanjeev K Singh, Jitendra K Saxena
Guanylate kinase is one of the key enzymes in nucleotide biosynthesis. The study highlights the structural and functional properties of Brugia malayi Guanylate kinase (BmGK) in the presence of chemical denaturants. An inactive, partially unfolded, dimeric intermediate was observed at 1-2M urea while GdnCl unfolding showed monomer molten globule like intermediate at 0.8-1.0M. The results also illustrate the protective role of substrates in maintaining the integrity of the enzyme. The thermo stability of protein was found to be significantly enhanced in the presence of the substrates...
October 14, 2016: International Journal of Biological Macromolecules
George Taylor-Walker, Savannah A Lynn, Eloise Keeling, Rosie Munday, David A Johnston, Anton Page, Jennifer A Scott, Srini Goverdhan, Andrew J Lotery, J Arjuna Ratnayaka
Age-related Macular Degeneration (AMD) is a common, irreversible blinding condition that leads to the loss of central vision. AMD has a complex aetiology with both genetic as well as environmental risks factors, and share many similarities with Alzheimer's disease. Recent findings have contributed significantly to unravelling its genetic architecture that is yet to be matched by molecular insights. Studies are made more challenging by observations that aged and AMD retinas accumulate the highly pathogenic Alzheimer's-related Amyloid beta (Aβ) group of peptides, for which there appears to be no clear genetic basis...
October 14, 2016: Experimental Eye Research
Rane A Harrison, Jia Lu, Martin Carrasco, John Hunter, Anuj Manandhar, Sudershan Gondi, Kenneth D Westover, John R Engen
Structural dynamics of Ras proteins contribute to their activity in signal transduction cascades. Directly targeting Ras proteins with small molecules may rely on movement of a conserved structural motif, switch II. To understand Ras signaling and advance Ras targeting strategies, experimental methods to measure Ras dynamics are required. Here we demonstrate the utility of hydrogen-deuterium exchange mass spectrometry to measure Ras dynamics by studying representatives from two branches of the Ras superfamily, Ras and Rho...
October 14, 2016: Journal of Molecular Biology
Cuilian Liu, Halei Zhai, Zhisen Zhang, Yaling Li, Xurong Xu, Ruikang Tang
Hydroxyapatite (HAP) nanocrystallites in all types of bones are distinguished by their ultrathin characteristics, which are uniaxially oriented with fibrillar collagen to uniquely expose the (100) faces. We speculate that living organisms prefer the specific crystal morphology and orientation of HAP because of the interactions between cells and crystals at the mineral-cell interface. Here, bone-like platy HAP (p-HAP) and two different rod-like HAPs were synthesized to investigate the ultrathin mineral modulating effect on cell bioactivity and bone generation...
October 18, 2016: ACS Applied Materials & Interfaces
Yongzhi Chang, Shuxi Zhou, Enqin Li, Wenfeng Zhao, Yanpeng Ji, Xiaoan Wen, Hongbin Sun, Haoliang Yuan
Cholesteryl Ester Transfer Protein (CETP) is an important therapeutic target for the treatment of atherosclerotic cardiovascular disease. Our molecular modeling study revealed that pentacyclic triterpenoid compounds could mimic the protein-ligand interactions of the endogenous ligand cholesteryl ester (CE) by occupying its binding site. Alignment of the docking conformations of oleanolic acid (OA), ursolic acid (UA) and the crystal conformations of known CETP inhibitor Torcetrapib in the active site proposed the applicability of fragment-based drug design (FBDD) approaches in this study...
September 30, 2016: European Journal of Medicinal Chemistry
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
Joanna J Hoppins, David R Gruber, Heather L Miears, Alexey S Kiryutin, Rustem D Kasymov, Darya V Petrova, Anton V Endutkin, Alexander V Popov, Alexandra V Yurkovskaya, Stanislav O Fedechkin, Jacob A Brockerman, Dmitry O Zharkov, Serge L Smirnov
8-oxoguanine is one of the most abundant and impactful oxidative DNA lesions. However, the reasons underlying its effects, especially those not directly explained by the altered base pairing ability, are poorly understood. We report the effect of the lesion on the action of EcoRI, a widely used restriction endonuclease. Introduction of 8-oxoguanine inside, or adjacent to, the GAATTC recognition site embedded within the Drew-Dickerson dodecamer sequence notably reduced the EcoRI activity. Solution NMR revealed that 8-oxoguanine in the DNA duplex causes substantial alterations in the sugar-phosphate backbone conformation, inducing a BI→BII transition...
2016: PloS One
Antoine Ducuing, Stéphane Vincent
The actin cable is a supracellular structure that embryonic epithelia produce to close gaps. However, the action of the cable remains debated. Here, we address the function of the cable using Drosophila dorsal closure, a paradigm to understand wound healing. First, we show that the actin cytoskeleton protein Zasp52 is specifically required for actin cable formation. Next, we used Zasp52 loss of function to dissect the mechanism of action of the cable. Surprisingly, closure dynamics are perfect in Zasp52 mutants: the cable is therefore dispensable for closure, even in the absence of the amnioserosa...
October 17, 2016: Nature Cell Biology
Yilong Tu, Shuai Ma, Fufeng Liu, Yan Sun, Xiaoyan Dong
Accumulation and aggregation of amyloid β-protein (Aβ) play an important role in the pathogenesis of Alzheimer's disease. There has been increased interest in finding new anti-amyloidogenic compounds to inhibit Aβ aggregation. Herein, thioflavin T fluorescent assay and transmission electron microscopy results showed that hematoxylin, a natural organic molecule extracted from caesalpinia sappan, was a powerful inhibitor of Aβ42 fibrillogenesis. Circular dichroism studies revealed hematoxylin reduced the β-sheet content of Aβ42 and made it assemble into antiparallel arrangement, which induced Aβ42 to form off-pathway aggregates...
October 17, 2016: Journal of Physical Chemistry. B
Magdalena Anna Mozolewska, Pawel Krupa, Bartlomiej Zaborowski, Adam Liwo, Jooyoung Lee, Keehyoung Joo, Cezary Czaplewski
Recently, we developed a new approach to protein-structure prediction, which combines template-based modeling with the physics-based coarse-grained UNited RESidue (UNRES) force field. In this approach, restrained multiplexed replica exchange molecular dynamics (MREMD) simulations with UNRES, with the C(α)-distance and virtual-bond-dihedral-angle restraints derived from knowledge-based models are carried out. In this work, we report a test of this approach in the 11th Community Wide Experiment on the Critical Assessment of Techniques for Protein Structure Prediction (CASP11), in which we used the template-based models from early-stage predictions by the LEE group CASP11 server (group 038, called 'nns'), and further improvement of the method...
October 17, 2016: Journal of Chemical Information and Modeling
L Tyler Mix, Julia Kirpich, Masato Kumauchi, Jie Ren, Mikas Vengris, Wouter D Hoff, Delmar S Larsen
We explored the photoisomerization mechanisms in novel homologs of Photoactive Yellow Protein (PYP) from Leptospira biflexa to identify conserved features and functional diversity in the primary photochemistry of this family of photoreceptors. In close agreement with the prototypical PYP from Halorhodospira halophila, we observe excited state absorbance near 375 nm and stimulated emission near 500 nm, with triphasic excited state decay. While the excited state decay for Lbif PYP is the slowest among known PYPs due to the redistribution of the amplitudes of the three decay components, the quantum yield for productive photocycle entry is very similar to that of Hhal PYP...
October 17, 2016: Biochemistry
John Lee
The molecular mechanisms of the bioluminescence systems of the firefly, bacteria, and those utilizing imidazopyrazinone luciferins such as coelenterazine, are gradually being uncovered using modern biophysical methods such as dynamic (ns-ps) fluorescence spectroscopy, NMR, X-ray crystallography, and computational chemistry. The chemical structures of all reactants are well defined and the spatial structures of the luciferases are providing important insight into interactions within the active cavity. It is generally accepted that the firefly and coelenterazine systems, although proceeding by different chemistries, both generate a dioxetanone high energy species that undergoes decarboxylation to form directly the product in its S1 state, the bioluminescence emitter...
October 17, 2016: Photochemistry and Photobiology
Qian Jiao, Li Wang, Zhichao Zhang, Yuanyuan Wang, Hanqi Yan, Wen Ma, Weilin Jin, Haixia Lu, Yong Liu
Different SLIT-ROBO Rho GTPase-activating proteins (srGAPs) have different levels of expression and diverse functions during neural development. Although srGAP2 is expressed in developmental brain tissue, little is known about its influence on cellular development of the nervous system. In the current study, dynamic expression of endogenous srGAP2 during neural stem cell/progenitor cell (NSC/NPC) differentiation in vitro was investigated in order to elucidate the association between the dynamic expression of srGAP2 and neural development...
October 4, 2016: Molecular Medicine Reports
Björn Over, Pär Matsson, Christian Tyrchan, Per Artursson, Bradley C Doak, Michael A Foley, Constanze Hilgendorf, Stephen E Johnston, Maurice D Lee, Richard J Lewis, Patrick McCarren, Giovanni Muncipinto, Ulf Norinder, Matthew W D Perry, Jeremy R Duvall, Jan Kihlberg
Macrocycles are of increasing interest as chemical probes and drugs for intractable targets like protein-protein interactions, but the determinants of their cell permeability and oral absorption are poorly understood. To enable rational design of cell-permeable macrocycles, we generated an extensive data set under consistent experimental conditions for more than 200 non-peptidic, de novo-designed macrocycles from the Broad Institute's diversity-oriented screening collection. This revealed how specific functional groups, substituents and molecular properties impact cell permeability...
October 17, 2016: Nature Chemical Biology
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