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Oligomerization

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https://www.readbyqxmd.com/read/29045884/effect-of-phosphate-ion-on-the-structure-of-lumazine-synthase-an-antigen-presentation-system-from-bacillus-anthracis
#1
Yangjie Wei, Newton Wahome, Prashant Kumar, Neal Whitaker, Wendy L Picking, C Russell Middaugh
Lumazine synthase (LS) is an oligomeric enzyme involved in the biosynthesis of riboflavin in microorganisms, fungi and plants. LS has become of significant interest to biomedical science because of its critical biological role and attractive structural properties for antigen presentation in vaccines. LS derived from Bacillus anthracis (BaLS) consists of 60 identical subunits forming an icosahedron. Its crystal structure has been solved, but its dynamic conformational properties have not yet been studied. We investigated the conformation of BaLS in response to different stress conditions (e...
October 15, 2017: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29045818/conformational-plasticity-of-hepatitis-c-virus-core-protein-enables-rna-induced-formation-of-nucleocapsid-like-particles
#2
Erik D Holmstrom, Daniel Nettels, Benjamin Schuler
Many of the unanswered questions associated with hepatitis C virus assembly are related to the core protein (HCVcp), which forms an oligomeric nucleocapsid encompassing the viral genome. The structural properties of HCVcp have been difficult to quantify, at least in part because it is an intrinsically disordered protein (IDP). We have used single-molecule FRET techniques to study the conformational dimensions and dynamics of the HCVcp nucleocapsid domain (HCVncd) at various stages during the RNA-induced formation of nucleocapsid-like particles...
October 15, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/29045138/importance-of-the-c-terminus-of-aldh7a1-for-oligomerization-and-catalytic-activity
#3
David Korasick, Jesse Wyatt, Min Luo, Adrian R Laciak, Kasi Ruddraraju, Kent S Gates, Michael T Henzl, John J Tanner
Aldehyde dehydrogenase 7A1 (ALDH7A1) catalyzes the terminal step of lysine catabolism, the NAD+-dependent oxidation of α-aminoadipate semialdehyde to α-aminoadipate. Structures of ALDH7A1 reveal the C-terminus is a gate that opens and closes in response to the binding of α-aminoadipate. In the closed state, the C-terminus of one protomer stabilizes the active site of the neighboring protomer in the dimer-of-dimers tetramer. Specifically, Ala505 and Gln506 interact with the conserved aldehyde-anchor-loop in the closed state...
October 18, 2017: Biochemistry
https://www.readbyqxmd.com/read/29045043/non-oxidative-coupling-of-methane-to-ethylene-using-mo2c-b-zsm-5
#4
Huibo F Sheng, Raul Francisco Lobo
Methane non-oxidative coupling to ethylene was investigated on Mo2C/[B]ZSM-5 catalyst at 923 K and atmospheric pressure. In contrast to Mo2C/[Al]ZSM-5 catalysts for methane aromatization, this material exhibits very high ethylene selectivity (>90%) and low aromatics (benzene and naphthalene) selectivity. The much weaker Brønsted acidity of [B]ZSM-5 leads to a slow rate of ethylene oligomerization. The stability of the catalyst is greatly enhanced with 93% of the initial reaction rate remaining after 18 h of time on stream...
October 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29044162/hetero-oligomer-of-dynamin-related-proteins-participates-in-the-fission-of-highly-divergent-mitochondria-from-entamoeba-histolytica
#5
Takashi Makiuchi, Herbert J Santos, Hiroshi Tachibana, Tomoyoshi Nozaki
Entamoeba histolytica is an anaerobic parasitic protist and possesses mitosomes, one of the most highly divergent mitochondrion-related organelles (MROs). Although unique metabolism and protein/metabolite transport machinery have been demonstrated in Entamoeba mitosomes, the mechanism of mitosomal fusion and fission remains to be elucidated. In this study, we demonstrate that two dynamin-related proteins (DRPs) are cooperatively involved in the fission of Entamoeba mitosomes. Expression of a dominant negative form of EhDrpA and EhDrpB, and alternatively, repression of gene expression of EhDrpA and EhDrpB genes, caused elongation of mitosomes, reflecting inhibition of mitosomal fission...
October 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29044096/a-homologue-of-the-parkinson-s-disease-associated-protein-lrrk2-undergoes-a-monomer-dimer-transition-during-gtp-turnover
#6
Egon Deyaert, Lina Wauters, Giambattista Guaitoli, Albert Konijnenberg, Margaux Leemans, Susanne Terheyden, Arsen Petrovic, Rodrigo Gallardo, Laura M Nederveen-Schippers, Panagiotis S Athanasopoulos, Henderikus Pots, Peter J M Van Haastert, Frank Sobott, Christian Johannes Gloeckner, Rouslan Efremov, Arjan Kortholt, Wim Versées
Mutations in LRRK2 are a common cause of genetic Parkinson's disease (PD). LRRK2 is a multi-domain Roco protein, harbouring kinase and GTPase activity. In analogy with a bacterial homologue, LRRK2 was proposed to act as a GTPase activated by dimerization (GAD), while recent reports suggest LRRK2 to exist under a monomeric and dimeric form in vivo. It is however unknown how LRRK2 oligomerization is regulated. Here, we show that oligomerization of a homologous bacterial Roco protein depends on the nucleotide load...
October 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/29043504/the-molecular-physiopathogenesis-of-islet-amyloidosis
#7
Diti Chatterjee Bhowmick, Sanghamitra Singh, Saurabh Trikha, Aleksandar M Jeremic
Human islet amyloid polypeptide or amylin (hA) is a 37-amino acid peptide hormone produced and co-secreted with insulin by pancreatic β-cells. Under physiological conditions, hA regulates a broad range of biological processes including insulin release and slowing of gastric emptying, thereby maintaining glucose homeostasis. However, under the pathological conditions associated with type 2 diabetes mellitus (T2DM), hA undergoes a conformational transition from soluble random coil monomers to alpha-helical oligomers and insoluble β-sheet amyloid fibrils or amyloid plaques...
October 18, 2017: Handbook of Experimental Pharmacology
https://www.readbyqxmd.com/read/29043433/mcpip1-inhibits-coxsackievirus-b3-replication-by-targeting-viral-rna-and-negatively-regulates-virus-induced-inflammation
#8
Min Li, Kepeng Yan, Lin Wei, Yang Yang, Qian Qian, Wei Xu
Monocyte chemotactic protein-induced protein 1(MCPIP1) is identified as an important inflammatory regulator during immune response. MCPIP1 possesses antiviral activities against several viruses, such as Japanese encephalitis. However, its role on Coxsackievirus B3 (CVB3) infection, a positive-stranded RNA virus, has not been addressed. Here, we reported that MCPIP1 was up-regulated in cardiomyocytes by CVB3 infection and in hearts and pancreas of infected mice. Then we found that overexpression of MCPIP1 inhibited CVB3 replication and knockdown of it promoted virus replication...
October 17, 2017: Medical Microbiology and Immunology
https://www.readbyqxmd.com/read/29042493/unraveling-the-self-assembly-of-the-pseudomonas-aeruginosa-xcpq-secretin-periplasmic-domain-provides-new-molecular-insights-into-type-ii-secretion-system-secreton-architecture-and-dynamics
#9
Badreddine Douzi, Nhung T T Trinh, Sandra Michel-Souzy, Aline Desmyter, Geneviève Ball, Pascale Barbier, Artemis Kosta, Eric Durand, Katrina T Forest, Christian Cambillau, Alain Roussel, Romé Voulhoux
The type II secretion system (T2SS) releases large folded exoproteins across the envelope of many Gram-negative pathogens. This secretion process therefore requires specific gating, interacting, and dynamics properties mainly operated by a bipartite outer membrane channel called secretin. We have a good understanding of the structure-function relationship of the pore-forming C-terminal domain of secretins. In contrast, the high flexibility of their periplasmic N-terminal domain has been an obstacle in obtaining the detailed structural information required to uncover its molecular function...
October 17, 2017: MBio
https://www.readbyqxmd.com/read/29041968/dynamic-changes-of-oligomeric-amyloid-%C3%AE-levels-in-plasma-induced-by-spiked-synthetic-a%C3%AE-42
#10
Seong Soo A An, Byoung-Sub Lee, Ji Sun Yu, Kuntaek Lim, Gwang Je Kim, Ryan Lee, Shinwon Kim, Sungmin Kang, Young Ho Park, Min Jeong Wang, Young Soon Yang, Young Chul Youn, SangYun Kim
BACKGROUND: A reliable blood-based assay is required to properly diagnose and monitor Alzheimer's disease (AD). Many attempts have been made to develop such a diagnostic tool by measuring amyloid-β oligomers (AβOs) in the blood, but none have been successful in terms of method reliability. We present a multimer detection system (MDS), initially developed for the detection of prion oligomers in the blood, to detect AβOs. METHODS: To characterize Aβ in the blood, plasma was spiked with synthetic amyloid-β (Aβ) and incubated over time...
October 17, 2017: Alzheimer's Research & Therapy
https://www.readbyqxmd.com/read/29040689/regulatory-dynamics-in-the-ternary-dnaa-complex-for-initiation-of-chromosomal-replication-in-escherichia-coli
#11
Yukari Sakiyama, Kazutoshi Kasho, Yasunori Noguchi, Hironori Kawakami, Tsutomu Katayama
In Escherichia coli, the level of the ATP-DnaA initiator is increased temporarily at the time of replication initiation. The replication origin, oriC, contains a duplex-unwinding element (DUE) flanking a DnaA-oligomerization region (DOR), which includes twelve DnaA-binding sites (DnaA boxes) and the DNA-bending protein IHF-binding site (IBS). Although complexes of IHF and ATP-DnaA assembly on the DOR unwind the DUE, the configuration of the crucial nucleoprotein complexes remains elusive. To resolve this, we analyzed individual DnaA protomers in the complex and here demonstrate that the DUE-DnaA-box-R1-IBS-DnaA-box-R5M region is essential for DUE unwinding...
October 10, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29039658/membrane-binding-and-pore-formation-by-a-cytotoxic-fragment-of-amyloid-%C3%AE-peptide
#12
Nabin Kandel, Tianyu Zheng, Qun Huo, Suren A Tatulian
Amyloid β (Aβ) peptide contributes to Alzheimer's disease by a yet unidentified mechanism. In brain tissue, Aβ occurs in various forms, including an undecapeptide Aβ25-35, which exerts neurotoxic effect through mitochondrial dysfunction and/or Ca(2+)-permeable pore formation in cell membranes. This work was aimed at biophysical characterization of membrane binding and pore formation by Aβ25-35. Interaction of Aβ25-35 with anionic and zwitterionic membranes was analyzed by microelectrophoresis. In pore formation experiments, Aβ25-35 was incubated in aqueous buffer to form oligomers and added to Quin-2-loaded vesicles...
October 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29039567/leptin-promotes-il%C3%A2-18-secretion-by-activating-the-nlrp3-inflammasome-in-raw-264-7-cells
#13
Sisi Fu, Lei Liu, Lei Han, Yiyun Yu
Leptin is a cytokine‑like hormone secreted by adipocytes, which serves to control energy expenditure and metabolism. In addition, leptin may modulate the innate and adaptive immune responses. The innate immune cell sensor nucleotide‑binding oligomerization domain‑like receptor family pyrin domain‑containing 3 (NLRP3) inflammasome is mainly expressed in myeloid immune cells, including macrophages. The NLRP3 inflammasome serves a pivotal role in the development and maintenance of autoimmunity and inflammation...
October 17, 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/29038815/distinct-oligomerization-and-fibrillization-dynamics-of-amyloid-core-sequences-of-amyloid-beta-and-islet-amyloid-polypeptide
#14
Yunxiang Sun, Bo Wang, Xinwei Ge, Feng Ding
A direct observation of amyloid aggregation from isolated peptides to cross-β fibrils is crucial for understanding the nucleation-dependence process, but the corresponding macroscopic timescales impose a major computational challenge. Using rapid all-atom discrete molecular dynamics simulations, we capture the oligomerization and fibrillization dynamics of the amyloid core sequences of amyloid-β (Aβ) in Alzheimer's disease and islet amyloid polypeptide (IAPP) in type-2 diabetes, namely Aβ16-22 and IAPP22-28...
October 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29038532/the-major-outer-sheath-protein-forms-distinct-conformers-and-multimeric-complexes-in-the-outer-membrane-and-periplasm-of-treponema-denticola
#15
Robbins Puthenveetil, Sanjiv Kumar, Melissa J Caimano, Abhishek Dey, Arvind Anand, Olga Vinogradova, Justin D Radolf
The major outer sheath protein (MOSP) is a prominent constituent of the cell envelope of Treponema denticola (TDE) and one of its principal virulence determinants. Bioinformatics predicts that MOSP consists of N- and C-terminal domains, MOSP(N) and MOSP(C). Biophysical analysis of constructs refolded in vitro demonstrated that MOSP(C), previously shown to possess porin activity, forms amphiphilic trimers, while MOSP(N) forms an extended hydrophilic monomer. In TDE and E. coli expressing MOSP with a PelB signal sequence (PelB-MOSP), MOSP(C) is OM-embedded and surface-exposed, while MOSP(N) resides in the periplasm...
October 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29038476/pro-angiogenic-effect-of-rantes-loaded-polysaccharide-based-microparticles-for-a-mouse-ischemia-therapy
#16
N Suffee, C Le Visage, H Hlawaty, R Aid-Launais, V Vanneaux, J Larghero, O Haddad, O Oudar, N Charnaux, A Sutton
Peripheral arterial disease results from the chronic obstruction of arteries leading to critical hindlimb ischemia. The aim was to develop a new therapeutic strategy of revascularization by using biodegradable and biocompatible polysaccharides-based microparticles (MP) to treat the mouse hindlimb ischemia. For this purpose, we deliver the pro-angiogenic chemokine Regulated upon Activation, Normal T-cell Expressed and Secreted (RANTES)/CCL5 in the mouse ischemic hindlimb, in solution or incorporated into polysaccharide-based microparticles...
October 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29037760/biochemical-differences-and-similarities-between-the-dead-box-helicase-orthologs-ddx3x-and-ded1p
#17
Deepak Sharma, Andrea A Putnam, Eckhard Jankowsky
DDX3X is a conserved DEAD-box RNA helicase involved in translation initiation and other processes of RNA metabolism. Mutations in human DDX3X and deregulation of its expression are linked to tumorigenesis and intellectual disability. The protein is also targeted by diverse viruses. Previous studies demonstrated helicase and NTPase activities for DDX3X, but important biochemical features of the enzyme remain unclear. Here, we systematically characterize enzymatic activities of human DDX3X and compare these to its closely related S...
October 13, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/29037718/co-fermentation-of-red-grapes-and-white-pomace-a-natural-and-economical-process-to-modulate-hybrid-wine-composition
#18
Paméla Nicolle, Charlène Marcotte, Paul Angers, Karine Pedneault
The impact of co-fermenting white grape pomace (WP) and red grape pomace (RP) on the composition of interspecific hybrid wine was studied using the Vitis sp. 'Frontenac' and 'Vidal'. The proanthocyanidin and anthocyanin content of the resulting wines were analysed by HPLC-fluorescence and UPLC-MS/MS, respectively. The CIELAB parameters and volatile compounds were analysed using spectrophotometry-UV and GC-MS-SPME, respectively. The WP addition increased the concentration of monomeric and oligomeric flavan-3-ols, and terpenes in the wines...
March 1, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29036655/mfib-a-repository-of-protein-complexes-with-mutual-folding-induced-by-binding
#19
Erzsébet Fichó, István Reményi, István Simon, Bálint Mészáros
Motivation: It is commonplace that intrinsically disordered proteins (IDPs) are involved in crucial interactions in the living cell. However, the study of protein complexes formed exclusively by IDPs is hindered by the lack of data and such analyses remain sporadic. Systematic studies benefited other types of protein-protein interactions paving a way from basic science to therapeutics; yet these efforts require reliable datasets that are currently lacking for synergistically folding complexes of IDPs...
August 3, 2017: Bioinformatics
https://www.readbyqxmd.com/read/29036409/structure-of-an-innexin-gap-junction-channel-and-cryo-em-sample-preparation
#20
Atsunori Oshima
Gap junction channels are essential for mediating intercellular communication in most multicellular organisms. Two gene families encode gap junction channels, innexin and connexin. Although the sequence similarity between these two families based on bioinformatics is not conclusively determined, the gap junction channels encoded by these two gene families are structurally and functionally analogous. We recently reported an atomic structure of an invertebrate innexin gap junction channel using single-particle cryo-electron microscopy...
September 21, 2017: Microscopy
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