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Chaperones

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https://www.readbyqxmd.com/read/27933579/oligomerization-and-chaperone-like-activity-of-drosophila-melanogaster-small-heat-shock-protein-dmhsp27-and-three-arginine-mutants-in-the-alpha-crystallin-domain
#1
Mohamed Taha Moutaoufik, Geneviève Morrow, Halim Maaroufi, Céline Férard, Stéphanie Finet, Robert M Tanguay
The small Hsp DmHsp27 from Drosophila melanogaster is one of the few small heat shock proteins (sHsps) found within the nucleus. We report that its dimerization is independent of disulfide bond formation and seems to rely on salt bridges. Unlike metazoan sHsps, DmHsp27 forms two populations of oligomers not in equilibrium. Mutations at highly conserved arginine residues in mammalian sHsps have been reported to be associated with protein conformational defects and intracellular aggregation. Independent mutation of three highly conserved arginines (R122, R131, and R135) to glycine in DmHsp27 results in only one population of higher molecular weight form...
December 8, 2016: Cell Stress & Chaperones
https://www.readbyqxmd.com/read/27932549/proteolytic-degradation-of-heat-shock-protein-a2-occurs-in-response-to-oxidative-stress-in-male-germ-cells-of-the-mouse
#2
Elizabeth G Bromfield, R John Aitken, Eileen A McLaughlin, Brett Nixon
STUDY QUESTION: Does oxidative stress compromise the protein expression of heat shock protein A2 (HSPA2) in the developing germ cells of the mouse testis? SUMMARY ANSWER: Oxidative stress leads to the modification of HSPA2 by the lipid aldehyde 4-hydroxynonenal (4HNE) and initiates its degradation via the ubiquitin-proteasome system. WHAT IS KNOWN ALREADY: Previous work has revealed a deficiency in HSPA2 protein expression within the spermatozoa of infertile men that have failed fertilization in a clinical setting...
December 8, 2016: Molecular Human Reproduction
https://www.readbyqxmd.com/read/27932462/salmonella-co-opts-host-cell-chaperone-mediated-autophagy-for-intracellular-growth
#3
Vikash Singh, Johannes Finke-Isami, Amanda C Hopper-Chidlaw, Peter Schwerk, Arthur Thompson, Karsten Tedin
Salmonella enterica are invasive, intracellular pathogens which replicate within a membrane-bound compartment inside infected host cells known as the Salmonella-containing vacuole (SCV). How Salmonella obtains nutrients for growth within this intracellular niche despite the apparent isolation is currently not known. Recent studies have indicated the importance of glucose and related carbon sources for tissue colonisation and intracellular proliferation within host cells during Salmonella infections, although none have been found to be essential...
December 8, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27932425/scn2b-deletion-in-mice-results-in-ventricular-and-atrial-arrhythmias
#4
Yangyang Bao, B Cicero Willis, Chad R Frasier, Luis F Lopez-Santiago, Xianming Lin, Roberto Ramos-Mondragón, David S Auerbach, Chunling Chen, Zhenxun Wang, Justus Anumonwo, Héctor H Valdivia, Mario Delmar, José Jalife, Lori L Isom
BACKGROUND: Mutations in SCN2B, encoding voltage-gated sodium channel β2-subunits, are associated with human cardiac arrhythmias, including atrial fibrillation and Brugada syndrome. Because of this, we propose that β2-subunits play critical roles in the establishment or maintenance of normal cardiac electric activity in vivo. METHODS AND RESULTS: To understand the pathophysiological roles of β2 in the heart, we investigated the cardiac phenotype of Scn2b null mice...
December 2016: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/27930307/cosmc-is-an-x-linked-inflammatory-bowel-disease-risk-gene-that-spatially-regulates-gut-microbiota-and-contributes-to-sex-specific-risk
#5
Matthew R Kudelka, Benjamin H Hinrichs, Trevor Darby, Carlos S Moreno, Hikaru Nishio, Christopher E Cutler, Jianmei Wang, Huixia Wu, Junwei Zeng, Yingchun Wang, Tongzhong Ju, Sean R Stowell, Asma Nusrat, Rheinallt M Jones, Andrew S Neish, Richard D Cummings
Inflammatory bowel disease (IBD) results from aberrant immune stimulation against a dysbiotic mucosal but relatively preserved luminal microbiota and preferentially affects males in early onset disease. However, factors contributing to sex-specific risk and the pattern of dysbiosis are largely unexplored. Core 1 β3GalT-specific molecular chaperone (Cosmc), which encodes an X-linked chaperone important for glycocalyx formation, was recently identified as an IBD risk factor by genome-wide association study. We deleted Cosmc in mouse intestinal epithelial cells (IECs) and found marked reduction of microbiota diversity in progression from the proximal to the distal gut mucosa, but not in the overlying lumen, as seen in IBD...
December 7, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27929117/cct-complex-restricts-neuropathogenic-protein-aggregation-via-autophagy
#6
Mariana Pavel, Sara Imarisio, Fiona M Menzies, Maria Jimenez-Sanchez, Farah H Siddiqi, Xiaoting Wu, Maurizio Renna, Cahir J O'Kane, Damian C Crowther, David C Rubinsztein
Aberrant protein aggregation is controlled by various chaperones, including CCT (chaperonin containing TCP-1)/TCP-1/TRiC. Mutated CCT4/5 subunits cause sensory neuropathy and CCT5 expression is decreased in Alzheimer's disease. Here, we show that CCT integrity is essential for autophagosome degradation in cells or Drosophila and this phenomenon is orchestrated by the actin cytoskeleton. When autophagic flux is reduced by compromise of individual CCT subunits, various disease-relevant autophagy substrates accumulate and aggregate...
December 8, 2016: Nature Communications
https://www.readbyqxmd.com/read/27928720/cardioprotection-of-exercise-preconditioning-involving-heat-shock-protein-70-and-concurrent-autophagy-a-potential-chaperone-assisted-selective-macroautophagy-effect
#7
Yang Yuan, Shan-Shan Pan, Yu-Jun Shen
It has been confirmed that exercise preconditioning (EP) has a protective effect on acute cardiovascular stress. However, how Hsp70 participates in EP-induced cardioprotection is unknown. EP may involve Hsp70 to repair unfolded proteins or may also stabilize the function of the endoplasmic reticulum via Hsp70-related autophagy to work on a protective formation. Our EP protocol involves four periods of 10 min running with 10 min recovery intervals. We added a period of exhaustive running to test this protective effect, using histology and molecular biotechnology methods to detect related markers...
December 7, 2016: Journal of Physiological Sciences: JPS
https://www.readbyqxmd.com/read/27927223/mitochondrial-co-chaperone-protein-tid1-is-required-for-energy-homeostasis-during-skeletal-myogenesis
#8
Li-Hao Cheng, Kai-Feng Hung, Te-Chang Lee, Chih-Yang Huang, Wen-Ting Chiu, Jeng-Fan Lo, Tung-Fu Huang
BACKGROUND: Tid1 is a mitochondrial co-chaperone protein and its transcript is abundantly expressed in skeletal muscle tissues. However, the physiological function of Tid1 during skeletal myogenesis remains unclear. METHODS: In vitro induced differentiation assay of mouse myoblast C2C12 cells was applied to examine the physiological role of Tid1 during skeletal myogenesis. In addition, transgenic mice with muscle specific (HSA-Cre) Tid1 deletion were established and examined to determine the physiological function of Tid1 during skeletal muscle development in vivo...
December 7, 2016: Stem Cell Research & Therapy
https://www.readbyqxmd.com/read/27926836/probing-small-molecule-binding-to-unfolded-polyprotein-based-on-its-elasticity-and-refolding
#9
Ricksen S Winardhi, Qingnan Tang, Jin Chen, Mingxi Yao, Jie Yan
Unfolded protein, a disordered structure found before folding of newly synthesized protein or after protein denaturation, is a substrate for binding by many cellular factors such as heat-stable proteins, chaperones, and many small molecules. However, it is challenging to directly probe such interactions in physiological solution conditions because proteins are largely in their folded state. In this work we probed small molecule binding to mechanically unfolded polyprotein using sodium dodecyl sulfate (SDS) as an example...
December 6, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27926536/a-minimal-titration-model-of-the-mammalian-dynamical-heat-shock-response
#10
Aude Sivéry, Emmanuel Courtade, Quentin Thommen
Environmental stress, such as oxidative or heat stress, induces the activation of the heat shock response (HSR) and leads to an increase in the heat shock proteins (HSPs) level. These HSPs act as molecular chaperones to maintain cellular proteostasis. Controlled by highly intricate regulatory mechanisms, having stress-induced activation and feedback regulations with multiple partners, the HSR is still incompletely understood. In this context, we propose a minimal molecular model for the gene regulatory network of the HSR that reproduces quantitatively different heat shock experiments both on heat shock factor 1 (HSF1) and HSPs activities...
December 7, 2016: Physical Biology
https://www.readbyqxmd.com/read/27925580/multiple-selection-filters-ensure-accurate-tail-anchored-membrane-protein-targeting
#11
Meera Rao, Voytek Okreglak, Un Seng Chio, Hyunju Cho, Peter Walter, Shu-Ou Shan
Accurate protein localization is crucial to generate and maintain organization in all cells. Achieving accuracy is challenging, as the molecular signals that dictate a protein's cellular destination are often promiscuous. A salient example is the targeting of an essential class of tail-anchored (TA) proteins, whose sole defining feature is a transmembrane domain near their C-terminus. Here we show that the Guided Entry of Tail-anchored protein (GET) pathway selects TA proteins destined to the endoplasmic reticulum (ER) utilizing distinct molecular steps, including differential binding by the co-chaperone Sgt2 and kinetic proofreading after ATP hydrolysis by the targeting factor Get3...
December 7, 2016: ELife
https://www.readbyqxmd.com/read/27924258/chaperonin-groel-uses-asymmetric-and-symmetric-reaction-cycles-in-response-to-the-concentration-of-non-native-substrate-proteins
#12
REVIEW
Ryo Iizuka, Takashi Funatsu
The Escherichia coli chaperonin GroEL is an essential molecular chaperone that mediates protein folding in association with its cofactor, GroES. It is widely accepted that GroEL alternates the GroES-sealed folding-active rings during the reaction cycle. In other words, an asymmetric GroEL-GroES complex is formed during the cycle, whereas a symmetric GroEL-(GroES)2 complex is not formed. However, this conventional view has been challenged by the recent reports indicating that such symmetric complexes can be formed in the GroEL-GroES reaction cycle...
2016: Biophysics and Physicobiology
https://www.readbyqxmd.com/read/27924075/histone-variants-on-the-move-substrates-for-chromatin-dynamics
#13
Paul B Talbert, Steven Henikoff
Most histones are assembled into nucleosomes behind the replication fork to package newly synthesized DNA. By contrast, histone variants, which are encoded by separate genes, are typically incorporated throughout the cell cycle. Histone variants can profoundly change chromatin properties, which in turn affect DNA replication and repair, transcription, and chromosome packaging and segregation. Recent advances in the study of histone replacement have elucidated the dynamic processes by which particular histone variants become substrates of histone chaperones, ATP-dependent chromatin remodellers and histone-modifying enzymes...
December 7, 2016: Nature Reviews. Molecular Cell Biology
https://www.readbyqxmd.com/read/27924001/histone-chaperone-activity-of-arabidopsis-thaliana-nrp1-is-blocked-by-cytochrome-c
#14
Katiuska González-Arzola, Antonio Díaz-Quintana, Francisco Rivero-Rodríguez, Adrián Velázquez-Campoy, Miguel A De la Rosa, Irene Díaz-Moreno
Higher-order plants and mammals use similar mechanisms to repair and tolerate oxidative DNA damage. Most studies on the DNA repair process have focused on yeast and mammals, in which histone chaperone-mediated nucleosome disassembly/reassembly is essential for DNA to be accessible to repair machinery. However, little is known about the specific role and modulation of histone chaperones in the context of DNA damage in plants. Here, the histone chaperone NRP1, which is closely related to human SET/TAF-Iβ, was found to exhibit nucleosome assembly activity in vitro and to accumulate in the chromatin of Arabidopsis thaliana after DNA breaks...
December 6, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27922674/2-hydroxycinnamaldehyde-induces-apoptosis-through-hsf1-mediated-bag3-expression
#15
Hai-Anh Nguyen, Soo-A Kim
BAG3, a member of BAG co-chaperone family, is induced by stressful stimuli such as heat shock and heavy metals. Through interaction with various binding partners, BAG3 is thought to play a role in cellular adaptive responses against stressful conditions in normal and neoplastic cells. 2'-Hydroxycinnamaldehyde (HCA) is a natural derivative of cinnamaldehyde and has antitumor activity in various cancer cells. In the present study, for the first time, we identified that HCA induced BAG3 expression and BAG3-mediated apoptosis in cancer cells...
December 6, 2016: International Journal of Oncology
https://www.readbyqxmd.com/read/27922280/ganetespib-for-small-cell-lung-cancer
#16
Deepa S Subramaniam, Eiran A Warner, Giuseppe Giaccone
Heat shock proteins (Hsps) are part of a complex network of chaperone proteins that are critically involved in the conformational maturation of intracellular proteins and regulate their degradation via the proteasome system Hsps (especially Hsp70 and Hsp90) are upregulated in many cancers and are potentially attractive therapeutic targets. Ganetespib is a potent non-geldanamycin analogue, and avoids the toxicities associated with older analogues due to its small molecular weight, lipophilicity and the absence of the benzoquinone moiety; strong pre-clinical data support its evaluation in lung cancer, especially small cell lung cancer (SCLC)...
December 6, 2016: Expert Opinion on Investigational Drugs
https://www.readbyqxmd.com/read/27920299/the-type-iii-secretion-system-effector-sptp-of-salmonella-enterica-serovar-typhi
#17
Rebecca Johnson, Alexander Byrne, Cedric N Berger, Elizabeth Klemm, Valerie F Crepin, Gordon Dougan, Gad Frankel
: Salmonella enterica serovars causes gastroenteritis or typhoid fever in humans, with virulence depending on the action of two type III secretion systems (SPI-1 and SPI-2). SptP is a Salmonella SPI-1 effector, involved in mediating recovery of the host cytoskeleton post-infection. SptP requires a chaperone, SicP, for stability and secretion. SptP has 94% identity between S Typhimurium and S Typhi; direct comparison of the protein sequences revealed that S Typhi SptP has numerous amino acid changes within its chaperone-binding domain...
December 5, 2016: Journal of Bacteriology
https://www.readbyqxmd.com/read/27920216/mozart1-and-%C3%AE-tubulin-complex-receptors-are-both-required-to-turn-%C3%AE-tusc-into-an-active-microtubule-nucleation-template
#18
Tien-Chen Lin, Annett Neuner, Dirk Flemming, Peng Liu, Takumi Chinen, Ursula Jäkle, Robert Arkowitz, Elmar Schiebel
MOZART1/Mzt1 is required for the localization of γ-tubulin complexes to microtubule (MT)-organizing centers from yeast to human cells. Nevertheless, the molecular function of MOZART1/Mzt1 is largely unknown. Taking advantage of the minimal MT nucleation system of Candida albicans, we reconstituted the interactions of Mzt1, γ-tubulin small complex (γ-TuSC), and γ-tubulin complex receptors (γ-TuCRs) Spc72 and Spc110 in vitro. With affinity measurements, domain deletion, and swapping, we show that Spc110 and Mzt1 bind to distinct regions of the γ-TuSC...
December 5, 2016: Journal of Cell Biology
https://www.readbyqxmd.com/read/27918543/ficd-acts-bifunctionally-to-ampylate-and-de-ampylate-the-endoplasmic-reticulum-chaperone-bip
#19
Steffen Preissler, Claudia Rato, Luke A Perera, Vladimir Saudek, David Ron
Protein folding homeostasis in the endoplasmic reticulum (ER) is defended by an unfolded protein response that matches ER chaperone capacity to the burden of unfolded proteins. As levels of unfolded proteins decline, a metazoan-specific FIC-domain-containing ER-localized enzyme (FICD) rapidly inactivates the major ER chaperone BiP by AMPylating T518. Here we show that the single catalytic domain of FICD can also release the attached AMP, restoring functionality to BiP. Consistent with a role for endogenous FICD in de-AMPylating BiP, FICD(-/-) hamster cells are hypersensitive to introduction of a constitutively AMPylating, de-AMPylation-defective mutant FICD...
December 5, 2016: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/27917864/multivalent-contacts-of-the-hsp70-ssb-contribute-to-its-architecture-on-ribosomes-and-nascent-chain-interaction
#20
Marie A Hanebuth, Roman Kityk, Sandra J Fries, Alok Jain, Allison Kriel, Veronique Albanese, Tancred Frickey, Christine Peter, Matthias P Mayer, Judith Frydman, Elke Deuerling
Hsp70 chaperones assist de novo folding of newly synthesized proteins in all cells. In yeast, the specialized Hsp70 Ssb directly binds to ribosomes. The structural basis and functional mode of recruitment of Ssb to ribosomes is not understood. Here, we present the molecular details underlying ribosome binding of Ssb in Saccharomyces cerevisiae. This interaction is multifaceted, involving the co-chaperone RAC and two specific regions within Ssb characterized by positive charges. The C-terminus of Ssb mediates the key contact and a second attachment point is provided by a KRR-motif in the substrate binding domain...
December 5, 2016: Nature Communications
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