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Unstructured Proteins

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https://www.readbyqxmd.com/read/28315679/charged-groups-at-binding-interfaces-of-the-psbo-subunit-of-photosystem-ii-a-combined-bioinformatics-and-simulation-study
#1
Coral Del Val, Ana-Nicoleta Bondar
PsbO is an extrinsic subunit of photosystem II engaged in complex binding interactions within photosystem II. At the interface between PsbO, D1 and D2 subunits of photosystem II, a cluster of charged and polar groups of PsbO is part of an extended hydrogen-bond network thought to participate in proton transfer. The precise role of specific amino acid residues at this complex binding interface remains a key open question. Here, we address this question by carrying out extensive bioinformatics analyses and molecular dynamics simulations of PsbO proteins with mutations at the binding interface...
March 15, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28297649/influence-of-flexible-%C3%AF-on-the-activity-of-e-%C3%A2-coli-rna-polymerase-a-thermodynamic-analysis
#2
Debipreeta Bhowmik, Neerupma Bhardwaj, Dipankar Chatterji
The Escherichia coli RNA polymerase (RNAP) is a multisubunit protein complex containing the smallest subunit, ω. Despite the evolutionary conservation of ω and its role in assembly of RNAP, E. coli mutants lacking rpoZ (codes for ω) are viable due to the association of RNAP with the global chaperone protein GroEL. With an aim to get better insight into the structure and functional role of ω, we isolated a dominant negative mutant of ω (ω6), which is predominantly α-helical, in contrast to largely unstructured native ω, and then studied its assembly with reconstituted core1 (α2ββ') by a biophysical approach...
March 14, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28295503/nuclear-magnetic-resonance-structure-of-the-human-polyoma-jc-virus-agnoprotein
#3
Pascale Coric, A Sami Saribas, Magid Abou-Gharbia, Wayne Childers, Jon Condra, Martyn K White, Mahmut Safak, Serge Bouaziz
Agnoprotein is an important regulatory protein of the human polyoma JC virus (JCV) and plays critical roles during the viral replication cycle. It forms highly stable dimers and oligomers through its Leu/Ile/Phe-rich domain, which is important for the stability and function of the protein. We recently resolved the partial 3D structure of this protein by NMR using a synthetic peptide encompassing amino acids Thr17 to Gln52, where the Leu/Ile/Phe- rich domain was found to adopt a major alpha-helix conformation spanning amino acids 23 to 39...
March 10, 2017: Journal of Cellular Biochemistry
https://www.readbyqxmd.com/read/28289188/ligand-induced-allostery-in-the-interaction-of-the-pseudomonas-aeruginosa-heme-binding-protein-with-heme-oxygenase
#4
Daniel J Deredge, Weiliang Huang, Colleen Hui, Hirotoshi Matsumura, Zhi Yue, Pierre Moënne-Loccoz, Jana Shen, Patrick L Wintrode, Angela Wilks
A heme-dependent conformational rearrangement of the C-terminal domain of heme binding protein (PhuS) is required for interaction with the iron-regulated heme oxygenase (HemO). Herein, we further investigate the underlying mechanism of this conformational rearrangement and its implications for heme transfer via site-directed mutagenesis, resonance Raman (RR), hydrogen-deuterium exchange MS (HDX-MS) methods, and molecular dynamics (MD). HDX-MS revealed that the apo-PhuS C-terminal α6/α7/α8-helices are largely unstructured, whereas the apo-PhuS H212R variant showed an increase in structure within these regions...
March 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28284018/chemical-shift-assignments-of-the-first-and-second-rrms-of-nrd1-a-fission-yeast-mapk-target-rna-binding-protein
#5
Ayaho Kobayashi, Teppei Kanaba, Ryosuke Satoh, Yutaka Ito, Reiko Sugiura, Masaki Mishima
Negative regulator differentiation 1 (Nrd1), a fission yeast RNA binding protein, modulates cytokinesis and sexual development and contributes to stress granule formation in response to environmental stresses. Nrd1 comprises four RRM domains and binds and stabilizes Cdc4 mRNA that encodes the myosin II light chain. Nrd1 binds the Cpc2 fission-yeast RACK1 homolog, and the interaction promotes Nrd1 localization to stress granules. Interestingly, Pmk1 mitogen-activated protein kinase phosphorylates Thr40 in the unstructured N-terminal region and Thr126 in the first RRM domain of Nrd1...
March 11, 2017: Biomolecular NMR Assignments
https://www.readbyqxmd.com/read/28272524/atomistic-structural-ensemble-refinement-reveals-non-native-structure-stabilizes-a-sub-millisecond-folding-intermediate-of-chey
#6
Jade Shi, R Paul Nobrega, Christian Schwantes, Sagar V Kathuria, Osman Bilsel, C Robert Matthews, T J Lane, Vijay S Pande
The dynamics of globular proteins can be described in terms of transitions between a folded native state and less-populated intermediates, or excited states, which can play critical roles in both protein folding and function. Excited states are by definition transient species, and therefore are difficult to characterize using current experimental techniques. Here, we report an atomistic model of the excited state ensemble of a stabilized mutant of an extensively studied flavodoxin fold protein CheY. We employed a hybrid simulation and experimental approach in which an aggregate 42 milliseconds of all-atom molecular dynamics were used as an informative prior for the structure of the excited state ensemble...
March 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28259129/structural-properties-of-potexvirus-coat-proteins-detected-by-optical-methods
#7
P I Semenyuk, O V Karpova, A L Ksenofontov, N O Kalinina, E N Dobrov, V V Makarov
It has been shown by X-ray analysis that cores of coat proteins (CPs) from three potexviruses, flexible helical RNA-containing plant viruses, have similar α-helical structure. However, this similarity cannot explain structural lability of potexvirus virions, which is believed to determine their biological activity. Here, we used circular dichroism (CD) spectroscopy in the far UV region to compare optical properties of CPs from three potexviruses with the same morphology and similar structure. CPs from Alternanthera mosaic virus (AltMV), potato aucuba mosaic virus (PAMV), and potato virus X (PVX) have been studied in a free state and in virions...
December 2016: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/28249940/a-structural-organization-for-disrupted-in-schizophrenia-1-identified-by-high-throughput-screening-reveals-distinctly-folded-regions-which-are-bisected-by-mental-illness-related-mutations
#8
Antony S K Yerabham, Philippe J Mas, Christina Decker, Dinesh C Soares, Oliver H Weiergräber, Luitgard Nagel-Steger, Dieter Willbold, Darren J Hart, Nicholas J Bradshaw, Carsten Korth
Disrupted in Schizophrenia 1 (DISC1) is a scaffolding protein of significant importance for neurodevelopment and a prominent candidate protein in the pathology of major mental illness. DISC1 modulates a number of critical neuronal signaling pathways through protein-protein interactions; however, the mechanism by which this occurs and how DISC1 causes mental illness is unclear, partly because knowledge of the structure of DISC1 is lacking. A lack of homology with known proteins has hindered attempts to define its domain composition...
March 1, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28249241/biophenols-pharmacology-against-the-amyloidogenic-activity-in-alzheimer-s-disease
#9
REVIEW
Syed Haris Omar
Alzheimer's disease characterized by misfolding, aggregation, and accumulation of amyloid fibrils in an insoluble form in the brain, is often known as amyloidosis. The process of aggregation follows a mechanism of seeded polymerization. For decades, a great number of failures in Alzheimer's disease (AD) drug development, with both small molecules and immunotherapies failing to establish a drug/placebo difference or having an unacceptable toxicity have led to the therapeutic research interest towards a group of anti-amyloidogenic compounds originated from plants called biophenols...
February 26, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28242466/elucidation-of-trna-cytochrome-c-interactions-through-hydrogen-deuterium-exchange-mass-spectrometry
#10
Yi-Ting Lo, Hung-Wei Huang, Yi-Chuan Huang, Jui-Fen Chan, Yuan-Hao Howard Hsu
Cytochrome c (cyt c) is a mitochondrial protein responsible for transferring electrons between electron transport chain complexes III and IV. The release of cyt c from the mitochondria has been considered as a commitment step in intrinsic apoptosis. Transfer RNA (tRNA) has recently been found to interact with the released cyt c to prevent the formation of the apoptosome complex, thus preventing cell apoptosis. To understand the molecular basis of tRNA-cyt c interactions, we applied hydrogen/deuterium exchange mass spectrometry (HDXMS) to analyze the interactions between tRNA and cyt c...
February 27, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28230082/tubz-filament-assembly-dynamics-requires-the-flexible-c-terminal-tail
#11
Maria E Fuentes-Pérez, Rafael Núñez-Ramírez, Alejandro Martín-González, David Juan-Rodríguez, Oscar Llorca, Fernando Moreno-Herrero, Maria A Oliva
Cytomotive filaments are essential for the spatial organization in cells, showing a dynamic behavior based on nucleotide hydrolysis. TubZ is a tubulin-like protein that functions in extrachromosomal DNA movement within bacteria. TubZ filaments grow in a helical fashion following treadmilling or dynamic instability, although the underlying mechanism is unclear. We have unraveled the molecular basis for filament assembly and dynamics combining electron and atomic force microscopy and biochemical analyses. Our findings suggest that GTP caps retain the filament helical structure and hydrolysis triggers filament stiffening upon disassembly...
February 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28218748/hiv-tat-protein-and-amyloid-%C3%AE-peptide-form-multifibrillar-structures-that-cause-neurotoxicity
#12
Alina Hategan, Mario A Bianchet, Joseph Steiner, Elena Karnaukhova, Eliezer Masliah, Adam Fields, Myoung-Hwa Lee, Alex M Dickens, Norman Haughey, Emilios K Dimitriadis, Avindra Nath
Deposition of amyloid-β plaques is increased in the brains of HIV-infected individuals, and the HIV transactivator of transcription (Tat) protein affects amyloidogenesis through several indirect mechanisms. Here, we investigated direct interactions between Tat and amyloid-β peptide. Our in vitro studies showed that in the presence of Tat, uniform amyloid fibrils become double twisted fibrils and further form populations of thick unstructured filaments and aggregates. Specifically, Tat binding to the exterior surfaces of the Aβ fibrils increases β-sheet formation and lateral aggregation into thick multifibrillar structures, thus producing fibers with increased rigidity and mechanical resistance...
February 20, 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/28214511/identification-of-a-degradation-signal-sequence-within-substrates-of-the-mitochondrial-i-aaa-protease
#13
Anthony J Rampello, Steven E Glynn
The i-AAA protease is a component of the mitochondrial quality control machinery that regulates respiration, mitochondrial dynamics, and protein import. The protease is required to select specific substrates for degradation from among the diverse complement of proteins present in mitochondria, yet the rules that govern this selection are unclear. Here, we reconstruct the yeast i-AAA protease, Yme1p, to examine the in vitro degradation of two intermembrane space chaperone subunits, Tim9 and Tim10. Yme1p degrades Tim10 more rapidly than Tim9 despite high sequence and structural similarity, and loss of Tim10 is accelerated by the disruption of conserved disulfide bonds within the substrate...
February 16, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28196861/molecular-determinants-of-the-n-terminal-acetyltransferase-naa60-anchoring-to-the-golgi-membrane
#14
Henriette Aksnes, Marianne Goris, Øyvind Strømland, Adrian Drazic, Qaiser Waheed, Nathalie Reuter, Thomas Arnesen
Nα-acetyltransferase 60 (Naa60 or NatF) was recently identified as an unconventional N-terminal acetyltransferase (NAT) since it localizes to organelles, in particular the Golgi apparatus, and has a preference for acetylating N-termini of transmembrane proteins. This knowledge challenged the prevailing view of N-terminal acetylation as a co-translational ribosome-associated process and suggested a new mechanistic functioning for the enzymes responsible for this increasingly recognized protein modification...
February 14, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28185903/the-thermodynamics-of-protein-aggregation-reactions-may-underpin-the-enhanced-metabolic-efficiency-associated-with-heterosis-some-balancing-selection-and-the-evolution-of-ploidy-levels
#15
REVIEW
B R Ginn
Identifying the physical basis of heterosis (or "hybrid vigor") has remained elusive despite over a hundred years of research on the subject. The three main theories of heterosis are dominance theory, overdominance theory, and epistasis theory. Kacser and Burns (1981) identified the molecular basis of dominance, which has greatly enhanced our understanding of its importance to heterosis. This paper aims to explain how overdominance, and some features of epistasis, can similarly emerge from the molecular dynamics of proteins...
February 6, 2017: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/28179526/a-sequence-independent-unstructured-ires-is-responsible-for-internal-expression-of-the-coat-protein-of-turnip-crinkle-virus
#16
Jared May, Philip Johnson, Huma Saleem, Anne E Simon
To maximize the coding potential of viral genomes, internal ribosome entry sites (IRES) can be used to bypass the traditional requirement of a 5' cap and some/all of the associated translation initiation factors. Although viral IRES typically contain higher order RNA structure, an unstructured sequence of about 84-nt immediately upstream of the Turnip crinkle virus (TCV) coat protein (CP) ORF has been found to promote internal expression of the CP from the genomic (g)RNA both in vitro and in vivo Absence of extensive RNA structure was predicted using RNA folding algorithms and confirmed by SHAPE structure probing...
February 8, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28157327/discrete-molecular-dynamics-approach-to-the-study-of-disordered-and-aggregating-proteins
#17
Agustí Emperador, Modesto Orozco
We present a refinement of the Coarse Grained PACSAB force field for Discrete Molecular Dynamics (DMD) simulations of proteins in aqueous conditions. As the original version, the refined method provides good representation of the structure and dynamics of folded proteins but provides much better representations of a variety of unfolded proteins, including some very large, impossible to analyze by atomistic simulation methods. The PACSAB/DMD method also reproduces accurately aggregation properties, providing good pictures of the structural ensembles of proteins showing a folded core and an intrinsically disordered region...
March 14, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28143508/prokaryotic-ubiquitin-like-protein-remains-intrinsically-disordered-when-covalently-attached-to-proteasomal-target-proteins
#18
Jonas Barandun, Fred F Damberger, Cyrille L Delley, Juerg Laederach, Frédéric H T Allain, Eilika Weber-Ban
BACKGROUND: The post-translational modification pathway referred to as pupylation marks proteins for proteasomal degradation in Mycobacterium tuberculosis and other actinobacteria by covalently attaching the small protein Pup (prokaryotic ubiquitin-like protein) to target lysine residues. In contrast to the functionally analogous eukaryotic ubiquitin, Pup is intrinsically disordered in its free form. Its unfolded state allows Pup to adopt different structures upon interaction with different binding partners like the Pup ligase PafA and the proteasomal ATPase Mpa...
February 1, 2017: BMC Structural Biology
https://www.readbyqxmd.com/read/28139759/the-intervening-domain-from-mecp2-enhances-the-dna-affinity-of-the-methyl-binding-domain-and-provides-an-independent-dna-interaction-site
#19
Rafael Claveria-Gimeno, Pilar M Lanuza, Ignacio Morales-Chueca, Olga C Jorge-Torres, Sonia Vega, Olga Abian, Manel Esteller, Adrian Velazquez-Campoy
Methyl-CpG binding protein 2 (MeCP2) preferentially interacts with methylated DNA and it is involved in epigenetic regulation and chromatin remodelling. Mutations in MeCP2 are linked to Rett syndrome, the leading cause of intellectual retardation in girls and causing mental, motor and growth impairment. Unstructured regions in MeCP2 provide the plasticity for establishing interactions with multiple binding partners. We present a biophysical characterization of the methyl binding domain (MBD) from MeCP2 reporting the contribution of flanking domains to its structural stability and dsDNA interaction...
January 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28138522/the-activation-loop-of-pip5k-functions-as-a-membrane-sensor-essential-for-lipid-substrate-processing
#20
Aizhuo Liu, Dexin Sui, Dianqing Wu, Jian Hu
Phosphatidylinositol 4-phosphate 5-kinase (PIP5K), a representative member of the phosphatidylinositol phosphate kinase (PIPK) family, is a major enzyme that biosynthesizes the signaling molecule PI(4,5)P2 (phosphatidylinositol 4,5-bisphosphate) in eukaryotic cells. The stringent specificity toward lipid substrates and the high sensitivity to the membrane environment strongly suggest a membrane-sensing mechanism, but the underlying structural basis is still largely unknown. We present a nuclear magnetic resonance (NMR) study on a peptide commensurate with a PIP5K's activation loop, which has been reported to be a determinant of lipid substrate specificity and subcellular localization of PIP5K...
November 2016: Science Advances
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