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Protein chaperones

Kun Zhang, Han Wang, Sandeep K Rajput, Joseph K Folger, George W Smith
Histone variant H3.3 is encoded by two distinct genes, H3F3A and H3F3B, that are closely associated with actively transcribed genes. H3.3 replacement is continuous and essential for maintaining correct chromatin structure during mouse oogenesis. Upon fertilization, H3.3 is incorporated to parental chromatin, and is required for blastocyst formation in mice. The H3.3 exchange process is facilitated by the chaperone HIRA, particularly during zygote development. We previously demonstrated that H3.3 is required for bovine early embryonic development; here, we explored the mechanisms of its functional requirement...
December 12, 2017: Molecular Reproduction and Development
Juan Camilo Moreno Beltran, Silvia Martinez-Jaime, Joram Schwartzmann, Daniel Karcher, Michael Tillich, Alexander Graf, Ralph Bock
The Clp protease in the chloroplasts of plant cells is a large complex composed of at least 13 nucleus-encoded subunits and one plastid-encoded subunit which are arranged in several ring-like structures. The proteolytic P-ring and the structurally similar R-ring form the core complex that contains the proteolytic chamber. Chaperones of the HSP100 family help with substrate unfolding and additional accessory proteins are believed to assist with Clp complex assembly and/or promote complex stability. Although structure and function of the Clp protease have been studied in great detail in both bacteria and chloroplasts, the identification of bona fide protease substrates has been very challenging...
December 11, 2017: Plant Physiology
Ganesan Karthikeyan, Alessio Bonucci, Gilles Casano, Guillaume Gerbaud, Sébastien Abel, Virginie Thomé, Laurent Kodjabachian, Axel Magalon, Bruno Guigliarelli, Valérie Belle, Olivier Ouari, Elisabetta Mileo
Approaching proteins structural dynamics and protein-protein interactions in the cellular environment is a fundamental challenge. Due to its absolute sensitivity and to its selectivity to paramagnetic species, Site-Directed Spin Labeling (SDSL) combined with Electron Paramagnetic Resonance (EPR) has the potential to evolve into an efficient method to follow conformational changes in proteins directly inside cells. Until now, the use of nitroxyde-based spin labels for in-cell studies has represented a major hurdle because of their short persistence in the cellular context...
December 11, 2017: Angewandte Chemie
Daiki Kashiwagi, Seunghyun Sim, Tatsuya Niwa, Hideki Taguchi, Takuzo Aida
Here we report molecular chaperone GroELs that carry, at their apical domains, multiple DNA strands (ideally 28 DNA strands in total) with defined oligonucleotide (nt) sequences. This design strategy allows for the preparation of GroEL10a and GroEL10b carrying 10-nt DNA strands of 10a and 10b with complementary sequences, respectively, at their apical domains (Table 1). One-dimensional coassembly of these GroELs is possible to form protein nanotube NT10a/10b with an anomalous thermodynamic stability due to the exceptionally large multivalency for the coassembly...
December 11, 2017: Journal of the American Chemical Society
Valentina L Kouznetsova, Hannah Hu, Knut Teigen, Maurizio Zanetti, Igor F Tsigelny
The ER resident chaperone molecule GRP78 has been shown to translocate to the cell surface where it associates with Cripto and signals cell growth, playing a still partially understood role in tumorigenesis. Consequently, a better understanding of GRP78 topology and structure at the surface of cancer cells represents an important step in the development of a new class of therapeutics. Here we used a set of programs for creation of a complex containing GRP78 and Cripto proteins. We elucidated possible interactions of GRP78, Cripto, and their complex with the membrane...
December 11, 2017: Protein Science: a Publication of the Protein Society
Mansoor Dehvari, Arezou Ghahghaei
The formation and deposition of protein fibrillar aggregates in the tissues is associated with several neurodegenerative diseases such as Alzheimer's and Parkinson's disease. Molecular chaperones are a family of proteins that are believed to have the ability to inhibit protein aggregation. The present study examines the effect of different concentrations of green synthesis silver nanoparticles (AgNPs) from Pulicaria undulata L. on the aggregation of α-lactalbumin (α-LA) and the chaperone action of αs-casein...
December 7, 2017: International Journal of Biological Macromolecules
Ye Lin, Xiaoyu Duan, He Lv, Yang Yang, Ying Liu, Xuejun Gao, Xiaoming Hou
The mammary gland requires the uptake of AA for milk protein synthesis during lactation. The L-type amino acid transporter 1 (LAT1, encoded by SLC7A5), found in many different types of mammalian cells, is indispensable as a transporter of essential AA to maintain cell growth and protein synthesis. However, the function of LAT1 in regulating milk protein synthesis in the mammary gland of the dairy cow remains largely unknown. For the current study, we characterized the relationship between LAT1 expression and milk protein synthesis in lactating dairy cows and investigated whether the mammalian target of rapamycin complex1 (mTORC1) signaling controls the expression of LAT1 in their mammary glands...
December 7, 2017: Journal of Dairy Science
Letizia Barbieri, Enrico Luchinat, Lucia Banci
DJ-1 is a conserved, ubiquitous protein associated to a large number of intracellular processes. Human DJ-1 has been linked to several pathologies, including hereditary forms of Parkinson's disease, cancer, and amyotrophic lateral sclerosis. Several cytoprotective functions of DJ-1 have been reported, however, its actual mechanisms of action remain elusive. In vitro, DJ-1 has been shown to bind zinc and copper(II) at its active site, which contains a conserved cysteine (C106), and copper(I) at a different binding site...
December 7, 2017: Journal of Biological Inorganic Chemistry: JBIC
Edna Grünblatt, Josefine Ruder, Camelia Maria Monoranu, Peter Riederer, Moussa Bh Youdim, Silvia A Mandel
Parkinson's disease is the most common neurodegenerative disorder after Alzheimer's disease, with the majority of cases being sporadic or "idiopathic". The aetiology of the sporadic form is still unknown, but there is a broad consensus that Parkinson's disease involves multiple pathways. In previous human post-mortem studies investigating substantia nigra of parkinsonian subjects, gene expression alterations in various metabolic pathways including protein folding, trafficking, aggregation, ubiquitination and oxidative stress were found...
December 7, 2017: Neurotoxicity Research
Lilian Varricchio, Mario Falchi, Massimiliano Dall'Ora, Caterina De Benedittis, Alessandra Ruggeri, Vladimir N Uversky, Anna Rita Migliaccio
Calreticulin is a Ca2+-binding chaperone protein, which resides mainly in the endoplasmic reticulum but also found in other cellular compartments including the plasma membrane. In addition to Ca2+, calreticulin binds and regulates almost all proteins and most of the mRNAs deciding their intracellular fate. The potential functions of calreticulin are so numerous that identification of all of them is becoming a nightmare. Still the recent discovery that patients affected by the Philadelphia-negative myeloproliferative disorders essential thrombocytemia or primary myelofibrosis not harboring JAK2 mutations carry instead calreticulin mutations disrupting its C-terminal domain has highlighted the clinical need to gain a deeper understanding of the biological activity of this protein...
2017: Frontiers in Cell and Developmental Biology
Zhicheng Yao, Ang Chen, Xin Li, Zhiyong Zhu, Xin Jiang
Heat shock protein 90 (Hsp90), a molecular chaperone, is involved in a variety of physiological and pathological processes. Targeting Hsp90 by small molecules has been developed as an attractive strategy of anticancer therapy. In this study, we investigated the mechanism of Hsp90 inhibitor suppresses CRC growth and potentiates effects of other chemotherapeutic drugs. We found that Hsp90 inhibitor induces chop-dependent DR5 upregulation regardless of p53 status. Furthermore, DR5 is required for Hsp90 inhibitor-induced apoptosis...
2017: American Journal of Translational Research
Shaon Chakrabarti, Changbong Hyeon, Xiang Ye, George H Lorimer, D Thirumalai
Molecular chaperones facilitate the folding of proteins and RNA in vivo. Under physiological conditions, the in vitro folding of Tetrahymena ribozyme by the RNA chaperone CYT-19 behaves paradoxically; increasing the chaperone concentration reduces the yield of native ribozymes. In contrast, the protein chaperone GroEL works as expected; the yield of the native substrate increases with chaperone concentration. The discrepant chaperone-assisted ribozyme folding thus contradicts the expectation that it operates as an efficient annealing machine...
December 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Valeriya V Mikhaylova, Tatiana B Eronina, Natalia A Chebotareva, Sergey Yu Kleymenov, Vladimir V Shubin, Boris I Kurganov
Different test systems are used to characterize the anti-aggregation efficiency of molecular chaperone proteins and of low-molecular-weight chemical chaperones. Test systems based on aggregation of UV-irradiated protein are of special interest because they allow studying the protective action of different agents at physiological temperatures. The kinetics of UV-irradiated glycogen phosphorylase b (UV-Phb) from rabbit skeletal muscle was studied at 37°C using dynamic light scattering in a wide range of protein concentrations...
2017: PloS One
Sahar Melamed, Raya Faigenbaum-Romm, Asaf Peer, Niv Reiss, Omer Shechter, Amir Bar, Yael Altuvia, Liron Argaman, Hanah Margalit
Small RNAs (sRNAs) are major post-transcriptional regulators of gene expression in bacteria. To enable transcriptome-wide mapping of bacterial sRNA-target pairs, we developed RIL-seq (RNA interaction by ligation and sequencing). RIL-seq is an experimental-computational methodology for capturing sRNA-target interactions in vivo that takes advantage of the mutual binding of the sRNA and target RNA molecules to the RNA chaperone protein Hfq. The experimental part of the protocol involves co-immunoprecipitation of Hfq and bound RNAs, ligation of RNAs, library preparation and sequencing...
January 2018: Nature Protocols
Joanna Brzeszczyńska, Angelika Meyer, Robin McGregor, Alain Schilb, Simone Degen, Valentina Tadini, Neil Johns, Ramon Langen, Annemie Schols, David J Glass, Ronenn Roubenoff, James A Ross, Kenneth C H Fearon, Carolyn A Greig, Carsten Jacobi
BACKGROUND: Sarcopenia is defined as the age-related loss of skeletal muscle mass and function. While all humans lose muscle with age, 2-5% of elderly adults develop functional consequences (disabilities). The aim of this study was to investigate muscle myogenesis in healthy elderly adults, with or without sarcopenia, compared with middle-aged controls using both in vivo and in vitro approaches to explore potential biomarker or causative molecular pathways associated with sarcopenic versus non-sarcopenic skeletal muscle phenotypes during ageing...
December 6, 2017: Journal of Cachexia, Sarcopenia and Muscle
Hui-Yong Lian, Kang-Wei Lin, Chuanjun Yang, Peng Cai
In this study, we studied the effect of 2.0 GHz radio frequency electromagnetic field (RF-EMF) and 50 Hz extremely low frequency electromagnetic field (ELF-EMF) exposure on prion generation and propagation using two budding yeast strains, NT64C and SB34, as model organisms. Under exposure to RF-EMF or ELF-EMF, the de novo generation and propagation of yeast prions [URE3] were elevated in both strains. The elevation increased over time, and the effects of ELF-EMF occurred in a dose-dependent manner. The transcription and expression levels of the molecular chaperones Hsp104, Hsp70-Ssa1/2, and Hsp40-Ydj1 were not statistically significantly changed after exposure...
December 6, 2017: Cell Stress & Chaperones
Joseph Newman, Amin S Asfor, Stephen Berryman, Terry Jackson, Stephen Curry, Tobias J Tuthill
Productive picornavirus infection requires the hijack of host cell pathways to aid with the different stages of virus entry, synthesis of the viral polyprotein and viral genome replication. Many picornaviruses, including foot-and-mouth disease virus (FMDV), assemble capsids via the multimerisation of several copies of a single capsid precursor protein into a pentameric subunit which further encapsidates the RNA. Pentamer formation is preceded by co- and post-translational modification of the capsid precursor (P1-2A) by viral and cellular enzymes, and the subsequent rearrangement of P1-2A into a structure amenable to pentamer formation...
December 6, 2017: Journal of Virology
Annika Scior, Alexander Buntru, Kristin Arnsburg, Anne Ast, Manuel Iburg, Katrin Juenemann, Maria Lucia Pigazzini, Barbara Mlody, Dmytro Puchkov, Josef Priller, Erich E Wanker, Alessandro Prigione, Janine Kirstein
Huntington's disease (HD) is a neurodegenerative disorder caused by an expanded CAG trinucleotide repeat in the huntingtin gene (HTT). Molecular chaperones have been implicated in suppressing or delaying the aggregation of mutant Htt. Using in vitro and in vivo assays, we have identified a trimeric chaperone complex (Hsc70, Hsp110, and J-protein) that completely suppresses fibrilization of HttExon1Q48 The composition of this chaperone complex is variable as recruitment of different chaperone family members forms distinct functional complexes...
December 6, 2017: EMBO Journal
Svetlana N Radyuk, William C Orr
<i>Significance:</i> Peroxiredoxins, a family of thiol-associated peroxidases, are purported to play a major role in sensing and managing H2O2 concentrations and transducing peroxide-derived signals. <i>Recent advances:</i> Peroxiredoxins can act as detoxifying factors and impart effects to cells that can be either sparing or suicidal. Advances have been made to address the qualitative changes in peroxiredoxin function in response to quantitative changes in the signal level and to understand how peroxidredoxin activity could be affected by their own substrates...
December 6, 2017: Antioxidants & Redox Signaling
Mark A Wilson
Wnt signaling proteins are fatty-acylated and bind to the protein afamin. The afamin-Wnt complex increases Wnt solubility dramatically and is likely involved in Wnt trafficking. In this issue of Structure, Naschberger et al. (2017) determine the crystal structure of afamin in complex with palmitoleic acid, revealing how afamin binds palmitoleoylated Wnt.
December 5, 2017: Structure
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