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Protein chaperones

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https://www.readbyqxmd.com/read/29045865/cooperative-nucleotide-binding-in-hsp90-and-its-regulation-by-aha1
#1
Philipp Wortmann, Markus Götz, Thorsten Hugel
The function of the molecular chaperone Hsp90 depends on large conformational changes, the rearrangement of local motifs, and the binding and hydrolysis of ATP. The size and complexity of the Hsp90 system impedes the detailed investigation of their interplay using standard methods. To overcome this limitation, we developed a three-color single-molecule FRET assay to study the interaction of Hsp90 with a fluorescently labeled reporter nucleotide in detail. It allows us to directly observe the cooperativity between the two nucleotide binding pockets in the protein dimer...
October 17, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/29045407/bayesian-refinement-of-protein-structures-and-ensembles-against-saxs-data-using-molecular-dynamics
#2
Roman Shevchuk, Jochen S Hub
Small-angle X-ray scattering is an increasingly popular technique used to detect protein structures and ensembles in solution. However, the refinement of structures and ensembles against SAXS data is often ambiguous due to the low information content of SAXS data, unknown systematic errors, and unknown scattering contributions from the solvent. We offer a solution to such problems by combining Bayesian inference with all-atom molecular dynamics simulations and explicit-solvent SAXS calculations. The Bayesian formulation correctly weights the SAXS data versus prior physical knowledge, it quantifies the precision or ambiguity of fitted structures and ensembles, and it accounts for unknown systematic errors due to poor buffer matching...
October 18, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29045036/endoplasmic-reticulum-stress-regulates-oxygen-glucose-deprivation-induced-parthanatos-in-human-sh-sy5y-cells-via-improvement-of-intracellular-ros
#3
Hai-Feng Wang, Zong-Qi Wang, Ye Ding, Mei-Hua Piao, Chun-Sheng Feng, Guang-Fan Chi, Yi-Nan Luo, Peng-Fei Ge
AIMS: Endoplasmic reticulum (ER) stress has been demonstrated to regulate neuronal death caused by ischemic insults via activation of apoptosis, but it still remains unclear whether ER stress participates in regulation of parthanatos, a new type of programmed cell death characterized by PARP-1 overactivation and intracellular accumulation of PAR polymer. METHODS: we used oxygen-glucose deprivation (OGD) and human SH-SY5Y cells to simulate neuronal damage caused by ischemia...
October 16, 2017: CNS Neuroscience & Therapeutics
https://www.readbyqxmd.com/read/29043681/the-unfolded-protein-response
#4
Kazuki Tabara, Yuji Iwata, Nozomu Koizumi
Under the unfolded protein response (UPR), transcripts encoding the endoplasmic reticulum (ER) chaperones are increased and those encoding proteins synthesized in the ER are decreased. To reproducibly detect such changes of an expression profile, homogeneous growth of plants is desired. In addition, uniform treatment with drugs inducing the UPR is also necessary. Here we describe our methods of plant culture and drug treatment, and procedure to detect gene expression by quantitative RT-PCR.
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29043503/pharmacoperones-for-misfolded-gonadotropin-receptors
#5
Claire L Newton, Ross C Anderson
The gonadotropin receptors (luteinising hormone receptor; LHR and follicle-stimulating hormone receptor; FSHR) are G protein-coupled receptors (GPCRs) that play an important role in the endocrine control of reproduction. Thus genetic mutations that cause impaired function of these receptors have been implicated in a number of reproductive disorders. Disease-causing genetic mutations in GPCRs frequently result in intracellular retention and degradation of the nascent protein through misfolding and subsequent recognition by cellular quality control machinery...
October 18, 2017: Handbook of Experimental Pharmacology
https://www.readbyqxmd.com/read/29042276/heterologous-expression-of-an-engineered-protein-domain-acts-as-chaperone-and-enhances-thermotolerance-of-escherichia-coli
#6
Rajender Jena, Dushyant K Garg, Lipsa Choudhury, Akanksha Saini, Bishwajit Kundu
Heat shock proteins (HSPs) are known to confer protection to the stressed cells by rescuing vital host cell proteins. In the present study we have demonstrated that heterologous expression of N-terminal domain of hyperthermophilic L-asparaginase (NPfA) confers thermotolerance to E. coli. The recombinant expression of NPfA enabled E. coli to demonstrate typical growth behavior at 52°C and survive a thermal shock up to 62°C, both being the highest reported temperatures for growth and heat shock survival. To understand the basis of protection proteome analysis of these cells was carried out which showed that NPfA guards a battery of proteins especially related to gene regulations and repair, providing definite survival advantage to the stressed cells...
October 14, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29042222/development-of-a-microarray-based-assay-for-efficient-testing-of-new-hsp70-dnak-inhibitors
#7
Sona Mohammadi-Ostad-Kalayeh, Vjaceslavs Hrupins, Sabine Helmsen, Frank Stahl, Thomas Scheper, Matthias Preller, Frank Surup, Marc Stadler, Andreas Kirschning, Carsten Zeilinger
A facile method for testing ATP binding in a highly miniaturized microarray environment using human HSP70 and DnaK from Mycobacterium tuberculosis as biological targets is reported. Supported by molecular modelling studies we demonstrate that the position of the fluorescence label on ATP has a strong influence on the binding to human HSP70. Importantly, the label has to be positioned on the adenine ring and not to the terminal phosphate group. Unlabelled ATP displaced bound Cy5-ATP from HSP70 in the micromolar range...
October 7, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/29040738/nf90-nf45-is-a-selective-rna-chaperone-that-rearranges-viral-and-cellular-riboswitches-biochemical-analysis-of-a-virus-host-factor-activity
#8
Tobias Schmidt, Susann Friedrich, Ralph Peter Golbik, Sven-Erik Behrens
The heterodimer NF90-NF45 is an RNA-binding protein complex that modulates the expression of various cellular mRNAs on the post-transcriptional level. Furthermore, it acts as a host factor that supports the replication of several RNA viruses. The molecular mechanisms underlying these activities have yet to be elucidated. Recently, we showed that the RNA-binding capabilities and binding specificity of NF90 considerably improves when it forms a complex with NF45. Here, we demonstrate that NF90 has a substrate-selective RNA chaperone activity (RCA) involving RNA annealing and strand displacement activities...
October 13, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29038656/unveiling-a-drift-resistant-cryptotope-within-marburgvirus-nucleoprotein-recognized-by-llama-single-domain-antibodies
#9
John Anthony Garza, Alexander Bryan Taylor, Laura Jo Sherwood, Peter John Hart, Andrew Hayhurst
Marburg virus (MARV) is a highly lethal hemorrhagic fever virus that is increasingly re-emerging in Africa, has been imported to both Europe and the US, and is also a Tier 1 bioterror threat. As a negative sense RNA virus, MARV has error prone replication which can yield progeny capable of evading countermeasures. To evaluate this vulnerability, we sought to determine the epitopes of 4 llama single-domain antibodies (sdAbs or VHH) specific for nucleoprotein (NP), each capable of forming MARV monoclonal affinity reagent sandwich assays...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/29038496/the-hsp70-homolog-ssb-affects-ribosome-biogenesis-via-the-torc1-sch9-signaling-pathway
#10
Kaivalya Mudholkar, Edith Fitzke, Claudia Prinz, Matthias P Mayer, Sabine Rospert
The Hsp70 Ssb serves a dual role in de novo protein folding and ribosome biogenesis; however, the mechanism by which Ssb affects ribosome production is unclear. Here we establish that Ssb is causally linked to the regulation of ribosome biogenesis via the TORC1-Sch9 signaling pathway. Ssb is bound to Sch9 posttranslationally and required for the TORC1-dependent phosphorylation of Sch9 at T737. Also, Sch9 lacking phosphorylation at T737 displays significantly reduced kinase activity with respect to targets involved in the regulation of ribosome biogenesis...
October 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/29037137/heterologous-expression-of-chaperones-from-hyperthermophilic-archaea-inhibits-aminoglycoside-induced-protein-misfolding-in-escherichia-coli
#11
S Peng, Z Chu, J Lu, D Li, Y Wang, S Yang, Y Zhang
Aminoglycoside antibiotics affect protein translation fidelity and lead to protein aggregation and an increase in intracellular oxidative stress level as well. The overexpression of the chaperonin GroEL/GroES system promotes short-term tolerance to aminoglycosides in Escherichia coli. Here, we demonstrated that the coexpression of prefoldin or Hsp60 originating from the hyperthermophilic archaeon Pyrococcus furiosus in E. coli cells can rescue cell growth and inhibit protein aggregation induced by streptomycin exposure...
October 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/29036702/a-hyperdynamic-h3-3-nucleosome-marks-promoter-regions-in-pluripotent-embryonic-stem-cells
#12
Sharon Schlesinger, Binyamin Kaffe, Shai Melcer, Jose D Aguilera, Divya M Sivaraman, Tommy Kaplan, Eran Meshorer
Histone variants and their chaperones are key regulators of eukaryotic transcription, and are critical for normal development. The histone variant H3.3 has been shown to play important roles in pluripotency and differentiation, and although its genome-wide patterns have been investigated, little is known about the role of its dynamic turnover in transcriptional regulation. To elucidate the role of H3.3 dynamics in embryonic stem cell (ESC) biology, we generated mouse ESC lines carrying a single copy of a doxycycline (Dox)-inducible HA-tagged version of H3...
September 25, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/29036673/enhanced-desiccation-tolerance-in-mature-cultures-of-the-streptophytic-green-alga-zygnema-circumcarinatum-revealed-by-transcriptomics
#13
Martin Rippin, Burkhard Becker, Andreas Holzinger
Desiccation tolerance is commonly regarded as one of the key features for the colonization of terrestrial habitats by green algae and the evolution of land plants. Extensive studies, focused mostly on physiology, have been carried out assessing the desiccation tolerance and resilience of the streptophytic genera Klebsormidium and Zygnema. Here we present transcriptomic analyses of Zygnema circumcarinatum exposed to desiccation stress. Cultures of Z. circumcarinatum, grown in liquid medium or on agar plates, were desiccated at ∼86% relative air humidity until Y(II) ceased...
September 22, 2017: Plant & Cell Physiology
https://www.readbyqxmd.com/read/29036198/the-homeodomain-interacting-protein-kinase-hpk-1-preserves-protein-homeostasis-and-longevity-through-master-regulatory-control-of-the-hsf-1-chaperone-network-and-torc1-restricted-autophagy-in-caenorhabditis-elegans
#14
Ritika Das, Justine A Melo, Manjunatha Thondamal, Elizabeth A Morton, Adam B Cornwell, Beresford Crick, Joung Heon Kim, Elliot W Swartz, Todd Lamitina, Peter M Douglas, Andrew V Samuelson
An extensive proteostatic network comprised of molecular chaperones and protein clearance mechanisms functions collectively to preserve the integrity and resiliency of the proteome. The efficacy of this network deteriorates during aging, coinciding with many clinical manifestations, including protein aggregation diseases of the nervous system. A decline in proteostasis can be delayed through the activation of cytoprotective transcriptional responses, which are sensitive to environmental stress and internal metabolic and physiological cues...
October 16, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/29035148/treatment-of-pulmonary-fibrosis-with-sirna-against-a-collagen-specific-chaperone-hsp47-in-vitamin-a-coupled-liposomes
#15
Mitsuo Otsuka, Masanori Shiratori, Hirofumi Chiba, Koji Kuronuma, Yasushi Sato, Yoshiro Niitsu, Hiroki Takahashi
BACKGROUND: Pulmonary fibrosis is a life-threatening pathological state of progressive interstitial lung diseases, such as idiopathic pulmonary fibrosis. Myofibroblasts are known to play a critical role in the pathogenesis of pulmonary fibrosis. This study aimed to evaluate the inhibitory effect of a small interfering RNA (siRNA) on a collagen-specific chaperone heat shock protein 47 (HSP47). The siRNA was preferentially delivered to myofibroblasts in a bleomycin (BLM)-induced pulmonary fibrosis rat model using siRNA against HSP47, encapsulated in a vitamin A-coupled liposome (VA-lip-siRNA HSP47)...
October 16, 2017: Experimental Lung Research
https://www.readbyqxmd.com/read/29034944/power-of-protein-trna-functional-assembly-against-aberrant-aggregation
#16
Charles Bou-Nader, Ludovic Pecqueur, David Cornu, Murielle Lombard, Manuela Dezi, Magali Nicaise, Christophe Velours, Marc Fontecave, Djemel Hamdane
Understanding the mechanisms of protein oligomerization and aggregation is a major concern for biotechnology and medical purposes. However, significant challenges remain in determining the mechanism of formation of these superstructures and the environmental factors that can precisely modulate them. Notably the role that a functional ligand plays in the process of protein aggregation is largely unexplored. We herein address these issues with an original flavin-dependent RNA methyltransferase (TrmFO) used as a protein model since this protein employs a complex set of cofactors and ligands for catalysis...
October 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29034805/in-vitro-investigation-of-the-effect-of-matrix-molecules-on-the-behavior-of-colon-cancer-cells-under-the-effect-of-geldanamycin-derivative
#17
Kamil Vural, Funda Kosova, Feyzan Özdal Kurt, İbrahim Tuğlu
The chaperone-binding drug, 17-allylamino-17-demethoxygeldanamycin, has recently come into clinical use. It is a derivative of geldanamycin, an ansamycin benzoquinone antibiotic with anti-carcinogenic effect. Understanding the effect of this drug on the cancer cells and their niche is important for treatment. We applied 17-allylamino-17-demethoxygeldanamycin to colon cancer cell line (Colo 205) on matrix molecules to investigate the relationship of apoptosis with terminal deoxynucleotidyl transferase dUTP nick end labeling immunocytochemistry and related gene expression...
October 2017: Tumour Biology: the Journal of the International Society for Oncodevelopmental Biology and Medicine
https://www.readbyqxmd.com/read/29033324/the-elongation-factor-spt6-maintains-esc-pluripotency-by-controlling-super-enhancers-and-counteracting-polycomb-proteins
#18
A Hongjun Wang, Aster H Juan, Kyung Dae Ko, Pei-Fang Tsai, Hossein Zare, Stefania Dell'Orso, Vittorio Sartorelli
Spt6 coordinates nucleosome dis- and re-assembly, transcriptional elongation, and mRNA processing. Here, we report that depleting Spt6 in embryonic stem cells (ESCs) reduced expression of pluripotency factors, increased expression of cell-lineage-affiliated developmental regulators, and induced cell morphological and biochemical changes indicative of ESC differentiation. Selective downregulation of pluripotency factors upon Spt6 depletion may be mechanistically explained by its enrichment at ESC super-enhancers, where Spt6 controls histone H3K27 acetylation and methylation and super-enhancer RNA transcription...
October 10, 2017: Molecular Cell
https://www.readbyqxmd.com/read/29032941/ferritin-iron-regulators-pcbp1-and-ncoa4-respond-to-cellular-iron-status-in-developing-red-cells
#19
Moon-Suhn Ryu, Kari A Duck, Caroline C Philpott
Developing red blood cells exhibit multiple, redundant systems for regulating and coordinating the uptake of iron, the synthesis of heme, and the formation of hemoglobin during terminal differentiation. We recently described the roles of poly rC-binding protein (PCBP1) and nuclear coactivator 4 (NCOA4) in mediating the flux of iron through ferritin in developing erythroid cells, with PCBP1, an iron chaperone, delivering iron to ferritin and NCOA4, an autophagic cargo receptor, directing ferritin to the lysosome for degradation and iron release...
September 28, 2017: Blood Cells, Molecules & Diseases
https://www.readbyqxmd.com/read/29032399/evidence-of-extracellular-vesicles-biogenesis-and-release-in-mouse-embryonic-stem-cells
#20
Lilian Cruz, Jenny Andrea Arevalo Romero, Mariana Brandão Prado, Tiago G Santos, Marilene Hohmuth Lopes
Extracellular vesicles (EVs) released by mouse embryonic stem cells (mESCs) are considered a source of bioactive molecules that modulate their microenvironment by acting on intercellular communication. Either intracellular endosomal machinery or their derived EVs have been considered a relevant system of signal circuits processing. Herein, we show that these features are found in mESCs. Ultrastructural analysis revealed structures and organelles of the endosomal system such as coated pits and endocytosis-related vesicles, prominent rough endoplasmic reticulum and Golgi apparatus, and multivesicular bodies (MVBs) containing either few or many intraluminal vesicles (ILVs) that could be released as exosomes to extracellular milieu...
October 14, 2017: Stem Cell Reviews
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