DOCSLIB.ORG

Decreased Interactions Between Calmodulin and a Mutant Huntingtin Model Might Reduce the Cytotoxic Level of Intracellular Ca2+: a Molecular Dynamics Study

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Decreased Interactions Between Calmodulin and a Mutant Huntingtin Model Might Reduce the Cytotoxic Level of Intracellular Ca2+: a Molecular Dynamics Study International Journal of Molecular Sciences Article Decreased Interactions between Calmodulin and a Mutant Huntingtin Model Might Reduce the Cytotoxic Level of Intracellular Ca2+: A Molecular Dynamics Study Sanda Nastasia Moldovean 1,2 and Vasile Chi¸s 1,2,* 1 Faculty of Physics, Babe¸s-BolyaiUniversity, Str. M. Kogălniceanu 1, RO-400084 Cluj-Napoca, Romania; [email protected] 2 Institute for Research, Development and Innovation in Applied Natural Sciences, Babes, -Bolyai University, Str. Fântânele 30, RO-400327 Cluj-Napoca, Romania * Correspondence: [email protected] Abstract: Mutant huntingtin (m-HTT) proteins and calmodulin (CaM) co-localize in the cerebral cortex with significant effects on the intracellular calcium levels by altering the specific calcium- mediated signals. Furthermore, the mutant huntingtin proteins show great affinity for CaM that can lead to a further stabilization of the mutant huntingtin aggregates. In this context, the present study focuses on describing the interactions between CaM and two huntingtin mutants from a biophysical point of view, by using classical Molecular Dynamics techniques. The huntingtin models consist of a wild-type structure, one mutant with 45 glutamine residues and the second mutant with nine additional key-point mutations from glutamine residues into proline residues (9P(EM) model). Our docking scores and binding free energy calculations show higher binding affinities of all HTT models Citation: Moldovean, S.N.; Chi¸s,V. for the C-lobe end of the CaM protein. In terms of dynamic evolution, the 9P(EM) model triggered Decreased Interactions between great structural changes into the CaM protein’s structure and shows the highest fluctuation rates due Calmodulin and a Mutant Huntingtin α Model Might Reduce the Cytotoxic to its structural transitions at the helical level from -helices to turns and random coils. Moreover, our Level of Intracellular Ca2+:A proposed 9P(EM) model suggests much lower interaction energies when compared to the 45Qs-HTT Molecular Dynamics Study. Int. J. mutant model, this finding being in good agreement with the 9P(EM)’s antagonistic effect hypothesis Mol. Sci. 2021, 22, 9025. https:// on highly toxic protein–protein interactions. doi.org/10.3390/ijms22169025 Keywords: calmodulin; calcium-binding protein; polyglutamine tract; polyglutamine disorders; Academic Editor: Stephan Huntington’s disease; molecular dynamics von Hörsten Received: 15 June 2021 Accepted: 18 August 2021 1. Introduction Published: 21 August 2021 The polyglutamine (polyQ) tract length of the mutant Huntingtin protein (m-HTT) is generally associated with the disease’s onset and its severity. The physiological Huntingtin Publisher’s Note: MDPI stays neutral protein is expressed in almost all body tissues and has a molecular weight of 348 kDa. with regard to jurisdictional claims in published maps and institutional affil- The polyQ tract is located at the protein’s N-terminal domain, which is followed by the iations. proline-rich domain (PRD) with a protective anti-aggregation role and a direct involvement in protein–protein interaction complexes [1]. Although the connection between Hunt- ingtin’s (HTT) structure and its function is not yet fully understood [2,3], the accumulation of insoluble aggregated N-terminal fragments of m-HTT together with their associated proteins, leads to loss of interruptions in the extended HTT sequence [4] and a wide range Copyright: © 2021 by the authors. of cell pathologies related to gene modifiers [5–7]. Licensee MDPI, Basel, Switzerland. The genetic defect in Huntington’s disease (HD) is characterized by the expansion of This article is an open access article the CAG trinucleotide repeats at the protein’s N-terminal domain. For normal controls, distributed under the terms and conditions of the Creative Commons which are considered as wild-type structures (wt-HTT), the polyQ tract (CAG trinucleotide Attribution (CC BY) license (https:// translates the glutamine amino acid) consists of less than 35 CAG repeats, while the m-HTT creativecommons.org/licenses/by/ is associated with a higher number of trinucleotide repeats [8]. 4.0/). Int. J. Mol. Sci. 2021, 22, 9025. https://doi.org/10.3390/ijms22169025 https://www.mdpi.com/journal/ijms Int. J. Mol. Sci. 2021, 22, 9025 2 of 16 The complex subcellular localization of the HTT structures triggers environmentally dependent conformational changes. Therefore, increasing evidence suggests that phospho- rylation at HTT-exon1’s level via specific kinases (Akt, ERK1, and Cdk5) [9] plays a crucial role in structures’ regulation, toxicity levels, and can affect cellular properties not only at the N-terminal domain but also on the full-length HTT sequence [10]. In HD brains or cell culture models of HD, the N-terminal domains also undergo other post-translational modifications such as acetylation. Moreover, the N-terminal regions may also be modified via ubiquitination and sumoylation [10]. For example, the insertion of mutations that mimic a phosphorylated protein, at both Ser-13 and Ser-16, has been shown to modify the levels of ubiquitination and acetylation, to influence HTT-exon1’s clearance and to increase the HTT nuclear localization [11,12]. Biochemical analysis of an HD rat brain also confirmed direct interactions between HTT structures and other interacting partners involved in cellular metabolism, intracellular signaling, and endocytic processes partly associated with clathrin-coated vesicles [13]. Since wild-type HTT structures are crucial in embryogenesis, through calcium regulations [14] and ATP transfer within cells [15], damages in HTT-related pathways may be caused not only by mutant HTT structures’ accumulation but also by the loss of function of the wild-type HTT proteins [15]. Several neurodegenerative disorders with amyloid-like fibrils implications, such as Alzheimer, Parkinson, or Huntington diseases, are associated with great alterations in calcium homeostasis [16]. Additionally, these alterations of Ca2+-dependent signaling path- ways are mainly present at the early stages of the previously mentioned diseases [16,17]. Ca2+ binding proteins are known to play essential roles in enzyme activation [18], gene expression, and proliferation [19]. Although their binding kinetic mechanisms remain unclear [20], they present a great impact on cell death processes by disturbing the Ca2+ homeostasis mechanisms [19,21,22]. Higher concentration levels of Ca2+ into the neuronal cytosolic environment were found in mutant HD mice models [23,24], where Ca2+-binding proteins’ expression and functioning are being altered [24]. The neuroprotective effects are particularly present in large-weight-protein com- plexes [25,26], where the activation of a Ca2+-activated cysteine protease is an almost irreversible process due to the increased cytosolic Ca2+ concentrations. Menzies et al. have demonstrated in Drosophila HD models that the inhibition of this cysteine protease called calpain has a positive effect on m-HTT’s aggregation and toxicity prevention [27]. This prevention is being outlined by an overexpression of calpain inhibitors that leads to an increased number of autophagosomes, facilitating the recycling mechanisms of dysfunctional or unnecessary cellular components [24,27]. At the genomics level, sev- eral studies [24,28–31] have revealed differences in the mRNAs of the genes, for discrete HD mouse models and patients, which are responsible for intracellular Ca2+-regulation proteins’ codification, as well as calcium-binding proteins such as calmodulin (CaM), cal- bindin, hypocalcin, and several particular receptors such as ryanodine receptor type 1 and voltage-gated Ca2+ channels [28–31]. It has been shown that m-HTT and calmodulin, a calcium-mediated protein that senses the calcium levels and activates particular signals to calcium-dependent or -sensitive enzymes, co-localizes with HTT’s inclusions in the cerebral cortex [25,32] with a direct effect on the dorsal striatum and other basal ganglia [33]. Moreover, the HTT mutants with an extended polyQ tract present higher affinity for CaM when compared to the wild-type HTT models, leading to the formation of monomeric HTT structures and further stabilization of the pre-formed m-HTT aggregates [19]. An excessive and uncontrolled influx of Ca2+ through the NMDA receptors has a direct effect on mitochondria, which plays the most important role in Ca2+ homeostasis in HD, where it disrupts the membrane potential, releasing cytochrome C and promoting cell death [34,35]. In addition, impaired calcium metabolism was observed in cardiomyopathy related to HD, where the cellular arrhythmia was accompanied by increased activity of Ca2+ and accordingly to calmodulin-dependent protein kinases [36]. Moreover, the intracellular calcium bindings by calmodulin could Int. J. Mol. Sci. 2021, 22, x FOR PEER REVIEW 3 of 16 Int. J. Mol. Sci. 2021, 22, 9025 3 of 16 could be crucial for proper cellular metabolism not only in CNS but also in all HD‐affected tissues [37]. be crucialCalmodulin for proper is a highly cellular conserved metabolism member not only of the in CNS EF‐hand but also proteins in all family HD-affected (Figure 1). Itstissues selective [37]. binding mechanism to calcium ions corresponds to the helix‐loop‐helix struc‐ turalCalmodulin motifs [38–40]. is a highlyCalmodulin conserved forms member two structurally of the EF-hand homologous proteins family globular (Figure (N‐ 1and). C‐ terminalIts selective lobes) binding domains mechanism related to to calcium the
Load more

Recommended publications
  • Polyq Disease: Misfiring of a Developmental Cell Death Program?
    Review PolyQ disease: misfiring of a developmental cell death program? * * Elyse S. Blum , Andrew R. Schwendeman , and Shai Shaham Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA Polyglutamine (polyQ) repeat diseases are neurodegen- death [10]. The linker cell dies in the normal course of erative ailments elicited by glutamine-encoding CAG nu- C. elegans development, during gonadal morphogenesis of cleotide expansions within endogenous human genes. the male [11–13] (Figure 1). Linker cell death is indepen- Despite efforts to understand the basis of these diseases, dent of caspases and all other known apoptotic and necrotic the precise mechanism of cell death remains stubbornly C. elegans cell-death genes [13,14]. Mutations in the pqn- unclear. Much of the data seem to be consistent with a 41 gene block linker cell death, suggesting an important model in which toxicity is an inherent property of the role in linker cell demise. Furthermore, transcription of polyQ repeat, whereas host protein sequences surround- pqn-41 is induced immediately before the onset of cell ing the polyQ expansion modulate severity, age of onset, death, suggesting that this locus may be intimately con- and cell specificity. Recently, a gene, pqn-41, encoding a nected with the killing process [10]. pqn-41 encodes multi- glutamine-rich protein, was found to promote normally ple alternative transcripts, most of which can encode a occurring non-apoptotic cell death in Caenorhabditis ele- domain of 427 amino-acids, of which 35% are glutamines, gans. Here we review evidence for toxic and modulatory arranged in tracts of 1–8 residues in length [10].
    [Show full text]
  • Datasheet: VMA00301KT Product Details
    Datasheet: VMA00301KT Description: TATA-BOX-BINDING PROTEIN ANTIBODY WITH CONTROL LYSATE Specificity: TATA-BOX-BINDING PROTEIN Format: Purified Product Type: PrecisionAb™ Monoclonal Isotype: IgG1 Quantity: 2 Westerns Product Details Applications This product has been reported to work in the following applications. This information is derived from testing within our laboratories, peer-reviewed publications or personal communications from the originators. Please refer to references indicated for further information. For general protocol recommendations, please visit www.bio-rad-antibodies.com/protocols. Yes No Not Determined Suggested Dilution Western Blotting 1/1000 PrecisionAb antibodies have been extensively validated for the western blot application. The antibody has been validated at the suggested dilution. Where this product has not been tested for use in a particular technique this does not necessarily exclude its use in such procedures. Further optimization may be required dependant on sample type. Target Species Human Product Form Purified IgG - liquid Preparation 20μl Mouse monoclonal antibody prepared by affinity chromatography on Protein G from ascites Buffer Solution Phosphate buffered saline Preservative 0.09% Sodium Azide (NaN ) Stabilisers 3 Immunogen Purified His-tagged TATA-box-binding protein External Database Links UniProt: P20226 Related reagents Entrez Gene: 6908 TBP Related reagents Synonyms GTF2D1, TF2D, TFIID Specificity Mouse anti Human TATA-box-binding protein antibody recognizes the TATA-box-binding protein,
    [Show full text]
  • Modifiers and Mechanisms of Multi-System Polyglutamine
    c Indian Academy of Sciences REVIEW ARTICLE Modifiers and mechanisms of multi-system polyglutamine neurodegenerative disorders: lessons from fly models MOUSHAMI MALLIK and SUBHASH C. LAKHOTIA* Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi 221 005, India Abstract Polyglutamine (polyQ) diseases, resulting from a dynamic expansion of glutamine repeats in a polypeptide, are a class of genetically inherited late onset neurodegenerative disorders which, despite expression of the mutated gene widely in brain and other tissues, affect defined subpopulations of neurons in a disease-specific manner. We briefly review the different polyQ- expansion-induced neurodegenerative disorders and the advantages of modelling them in Drosophila. Studies using the fly models have successfully identified a variety of genetic modifiers and have helped in understanding some of the molec- ular events that follow expression of the abnormal polyQ proteins. Expression of the mutant polyQ proteins causes, as a consequence of intra-cellular and inter-cellular networking, mis-regulation at multiple steps like transcriptional and post- transcriptional regulations, cell signalling, protein quality control systems (protein folding and degradation networks), axonal transport machinery etc., in the sensitive neurons, resulting ultimately in their death. The diversity of genetic modifiers of polyQ toxicity identified through extensive genetic screens in fly and other models clearly reflects a complex network effect of the presence of the mutated protein. Such network effects pose a major challenge for therapeutic applications. [Mallik M. and Lakhotia S. C. 2010 Modifiers and mechanisms of multi-system polyglutamine neurodegenerative disorders: lessons from fly models. J. Genet. 89, 497–526] Introduction of mutations which bring about expansion of unstable trinu- cleotide repeats in the genome.
    [Show full text]
  • Molecular Pathogenesis of Spinocerebellar Ataxia Type 6
    Neurotherapeutics: The Journal of the American Society for Experimental NeuroTherapeutics Molecular Pathogenesis of Spinocerebellar Ataxia Type 6 Holly B. Kordasiewicz* and Christopher M. Gomez† *Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, California 92093; †Department of Neurology, University of Chicago, Chicago, Illinois 60637 Summary: Spinocerebellar ataxia type 6 (SCA6) is a neuro- to modulate or correct ion channel function. Alternatively, as a degenerative disorder caused by abnormal expansions of a disease in which the mutant protein contains an expanded poly- trinucleotide CAG repeat in exon 47 of the CACNA1A gene, glutamine tract, SCA6 may respond to the targets of drug which encodes the ␣1A subunit of the P/Q-type voltage-gated therapies developed for Huntington’s disease and other poly- calcium channel. The CAG repeat expansion is translated into glutamine disorders. In this review we will compare SCA6 to an elongated polyglutamine tract in the carboxyl terminus of other polyglutamine diseases and channelopathies, and we will ␣ ␣ the 1A subunit. The 1A subunit is the main pore-forming highlight recent advances in our understanding of ␣1A subunits subunit of the P/Q-type calcium channel. Patients with SCA6 and SCA6 pathology. We also propose a mechanism for how suffer from a severe form of progressive ataxia and cerebellar two seemingly divergent hypotheses can be combined into a dysfunction. Design of treatments for this disorder will depend cohesive model for disease progression. Key Words: Spino- on better definition of the mechanism of disease. As a disease cerebellar ataxia type 6 (SCA6), channelopathy, polyglutamine arising from a mutation in an ion channel gene, SCA6 may behave as an ion channelopathy, and may respond to attempts disease, P/Q-type calcium channel, Purkinje cell, cerebellum.
    [Show full text]
  • Polyglutamine Tract Binding Protein-1 Is an Intrinsically Unstructured Protein
    Biochimica et Biophysica Acta 1794 (2009) 936–943 Contents lists available at ScienceDirect Biochimica et Biophysica Acta journal homepage: www.elsevier.com/locate/bbapap Polyglutamine tract binding protein-1 is an intrinsically unstructured protein Masaki Takahashi a, Mineyuki Mizuguchi a,⁎, Hiroyuki Shinoda a, Tomoyasu Aizawa b, Makoto Demura b, Hitoshi Okazawa c, Keiichi Kawano b a Faculty of Pharmaceutical Sciences, University of Toyama, 2630, Sugitani, Toyama 930-0194, Japan b Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan c Department of Neuropathology, Medical Research Institute and 21st Century Center of Excellence Program (COE) for Brain Integration and Its Disorders, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan article info abstract Article history: Polyglutamine tract binding protein-1 (PQBP-1) is a nuclear protein that interacts with disease proteins Received 30 September 2008 containing expanded polyglutamine repeats. PQBP-1 also interacts with RNA polymerase II and a Received in revised form 27 February 2009 spliceosomal protein U5-15kD. In the present study, we demonstrate that PQBP-1 is composed of a large Accepted 3 March 2009 unstructured region and a small folded core. Intriguingly, the large unstructured region encompasses two Available online 17 March 2009 functional domains: a polar amino acid rich domain and a C-terminal domain. These findings suggest that Keywords: PQBP-1 belongs to the family of intrinsically unstructured/disordered proteins. Furthermore, the binding of Unstructured protein the target molecule U5-15kD induces only minor conformational changes into PQBP-1. Our results suggest Protein structure that PQBP-1 includes high content of unstructured regions in the C-terminal domain, in spite of the binding PQBP-1 of U5-15kD.
    [Show full text]
  • Evolving Notch Polyq Tracts Reveal Possible Solenoid Interference Elements
    bioRxiv preprint doi: https://doi.org/10.1101/079038; this version posted October 3, 2016. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. Evolving Notch polyQ tracts reveal possible solenoid interference elements Albert J. Erives Department of Biology University of Iowa Iowa City, IA, USA 52242-1324 E-mail: [email protected] 1 bioRxiv preprint doi: https://doi.org/10.1101/079038; this version posted October 3, 2016. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. ABSTRACT Polyglutamine (polyQ) tracts in regulatory proteins are extremely polymorphic. As functional elements under selection for length, triplet repeats are prone to DNA replication slippage and indel mutations. Many polyQ tracts are also embedded within intrinsically disordered domains, which are less constrained, fast evolving, and difficult to characterize. To identify structural principles underlying polyQ tracts in disordered regulatory domains, here I analyze deep evolution of metazoan Notch polyQ tracts, which can generate alleles causing developmental and neurogenic defects. I show that Notch features polyQ tract turnover that is restricted to a discrete number of conserved “polyQ insertion slots”. Notch polyQ insertion slots are: (i) identifiable by an amphipathic “slot leader” motif; (ii) conserved as an intact C-terminal array in a 1-to-1 relationship with the N-terminal solenoid-forming ankyrin repeats (ARs); and (iii) enriched in carboxamide residues (Q/N), whose sidechains feature dual hydrogen bond donor and acceptor atoms.
    [Show full text]
  • Ataxin the Brain
    HIGHLIGHTS The ultimate fate of the sling cells NEURODEGENERATIVE DISEASE remains a mystery. It was previously thought that they underwent pro- grammed cell death. However, although Shu et al. identified a few Ataxin the brain apoptotic cells in the sling just before birth, the extent of cell death was insufficient to account for its disap- Polyglutamine diseases — presently untreatable pearance. The authors therefore human neurodegenerative disorders that include make the tantalizing suggestion Huntington’s disease and several types of that the sling neurons might survive spinocerebellar ataxia (SCA) — are associated and migrate to other regions of the with expansion of CAG trinucleotide repeats. brain. The question of where In SCA type 1, elevated polyglutamine the cells go, and what contribution, concentration occurs in the kinase ataxin-1, and if any, they make to the adult brain, accumulation of this protein is often seen in the should provide ample scope for neuronal nuclei. Now, reports published in 8 May future study. issue of Neuron and 16 May issue of Cell Heather Wood demonstrate that phosphorylation of ataxin-1 plays a crucial role in SCA type 1 pathogenesis. References and links In neurons of SCA1 transgenic mice, a mutated ORIGINAL RESEARCH PAPER Shu, T. et al. The glial sling is a migratory population of developing gene encoding ataxin-1 directs production of the neurons. Development 130, 2929–2937 (2003) protein with an increasing number of consecutive FURTHER READING Silver, J. et al. Axonal residues of the amino acid glutamine, which leads guidance during development of the great cerebral commissures: descriptive and to the formation of nuclear inclusions.
    [Show full text]
  • Highlights of Kennedy's Disease
    Pia et al. Int J Neurol Neurother 2016, 3:057 International Journal of DOI: 10.23937/2378-3001/3/5/1057 Volume 3 | Issue 5 Neurology and Neurotherapy ISSN: 2378-3001 Letter to the Editor: Open Access Highlights of Kennedy’s Disease Agustina Pia Marengo1*, Fernando Guerrero Pérez1, Rocío Valera Yepes2 and Carles Villabona Artero2 1Hospital Universitari Bellvitge, Barcelona, España, Spain 2Hospital de Viladecans, Barcelona, España, Spain *Corresponding author: Marengo Agustina, Endocrinology and Nutrition Unit (15), Hospital Universitari Bellvitge, Feixa Llarga s/n, 08907, L’Hospitalet de Llobregat, Barcelona, Spain, E-mail: [email protected]. Women carrying the mutant AR allele are clinically unaffected, Keywords and they only show, in rare cases, abnormal electromyograms and Bulbar and spinal muscular atrophy, Kennedy’s disease, Androgen the appearance of occasional muscle cramps and tremors in advance insensivity ages [2]. It is possible that the physiological random inactivation of the X-chromosome in female may preserve at least 50% of total Letter to the Editor motoneurons, and this may be sufficient to maintain normal locomotor activity. However, in 2002, Schmidt, et al. [10] reported Bulbar and spinal muscular atrophy, also called Kennedy’s a study with two homozygous women for KD who did not show Disease (KD), is a very rare neurodegenerative disease, with onset in clinical signs of neurodegeneration. Thus the AR polyglutamine tract adult males usually in the fourth or fifth decade [1]. Kennedy disease neurotoxicity may be activated in men by other factors, for instance is named after William Kennedy, MD, who described this condition the hormonal steroid testosterone [5].
    [Show full text]
  • Polyglutamine Neurodegenerative Diseases and Regulation of Transcription: Assembling the Puzzle
    Downloaded from genesdev.cshlp.org on October 6, 2021 - Published by Cold Spring Harbor Laboratory Press REVIEW Polyglutamine neurodegenerative diseases and regulation of transcription: assembling the puzzle Brigit E. Riley1,3,4 and Harry T. Orr1,2,3,5 1Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA; 2Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota 55455, USA; 3Institute of Human Genetics, University of Minnesota, Minneapolis, Minnesota 55455, USA The polyglutamine disorders are a class of nine neuro- mechanism of pathogenesis entirely dependent on the degenerative disorders that are inherited gain-of-func- toxic properties of the polyglutamine tract. This typi- tion diseases caused by expansion of a translated CAG cally centered on the enhanced ability of polyglutamine repeat. Even though the disease-causing proteins are peptides to form intranuclear aggregates/inclusions widely expressed, specific collections of neurons are (Ross and Poirer 2004). The presence of these aggregates/ more susceptible in each disease, resulting in character- inclusions within the nuclei of affected neurons focused istic patterns of pathology and clinical symptoms. One attention on the nucleus as the subcellular site impor- hypothesis poses that altered protein function is funda- tant in pathogenesis. After much study, the concept of mental to pathogenesis, with protein context of the ex- large aggregates/inclusions of mutant polyglutamine as panded polyglutamine having key roles in disease- the pathogenic species has become suspect (Arrasate et specific processes. This review will focus on the role of al. 2004). However, for many of the polyglutamine dis- the disease-causing polyglutamine proteins in gene tran- orders, understanding events in the nucleus still remains scription and the extent to which the mutant proteins crucial for comprehending pathogenesis.
    [Show full text]
  • Polyglutamine Tracts As Modulators of Transcriptional Activation from Yeast to Mammals
    Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 2012 Polyglutamine tracts as modulators of transcriptional activation from yeast to mammals Atanesyan, L ; Güther, V ; Dichtl, B ; Georgiev, O ; Schaffner, W Abstract: Abstract Microsatellite repeats are genetically unstable and subject to expansion and shrinkage. A subset of them, triplet repeats, can occur within the coding region and specify homomeric tracts of amino acids. Polyglutamine (polyQ) tracts are enriched in eukaryotic regulatory proteins, notably transcription factors, and we had shown before that they can contribute to transcriptional activation in mammalian cells. Here we generalize this finding by also including evolutionarily divergent organisms, namely, Drosophila and baker’s yeast. In all three systems, Gal4-based model transcription factors were more active if they harbored a polyQ tract, and the activity depended on the length of the tract. By contrast, a polyserine tract was inactive. PolyQs acted from either an internal or a C-terminal position, thus ruling out a merely structural ”linker” effect. Finally, a two-hybrid assay in mammalian cells showed that polyQ tracts can interact with each other, supporting the concept that a polyQ-containing transcription factor can recruit other factors with polyQ tracts or glutamine-rich activation domains. The widespread occurrence of polyglutamine repeats in regulatory proteins suggests a beneficial role; in addition to the contribution to transcriptional activity, their genetic instability might help a species to adapt to changing environmental conditions in a potentially reversible manner. DOI: https://doi.org/10.1515/BC-2011-252 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-53024 Journal Article Published Version Originally published at: Atanesyan, L; Güther, V; Dichtl, B; Georgiev, O; Schaffner, W (2012).
    [Show full text]
  • TATA Binding Protein Antibody (1TBP18)
    Lot Number: PG1884201I TATA binding protein Antibody (1TBP18) Product Data Sheet Tested Species Reactivity Published Species Reactivity Details Human (Hu) Human (Hu) Catalog Number: MA1-21516 Mouse (Ms) Size: 100 µg Rat (Rt) Class: Monoclonal Type: Antibody Tested Applications Dilution * Clone: 1TBP18 Western Blot (WB) Assay dependent Host / Isotype: Mouse / IgG1 Immunoprecipitation (IP) Assay dependent Synthetic peptide corresponding to Gel Shift (GS) Assay dependent Immunogen: the N-terminal residues 1-20 of human, mouse, and rat TBP. Published Applications Dilution Western Blot (WB) See publications Form Information * Suggested working dilutions are given as a guide only. It is recommended that the user titrates the product for use in their own experiment using appropriate negative and positive controls. Form: Liquid Concentration: 1.3mg/ml Purification: Protein G Storage Buffer: PBS Preservative: 0.02% sodium azide Storage Conditions: -20° C, Avoid Freeze/Thaw Cycles Product Specific Information General Information MA1-21516 detects TATA binding protein (TBP) in human, mouse, and rat Initiation of transcription by RNA polymerase II requires the activities of samples. This antibody does not cross-react with Drosophila melanogaster, more than 70 polypeptides. The protein that coordinates these activities is S. cerevisiae, silk worm, or Xenopus laevis. transcription factor IID (TFIID), which binds to the core promoter to position the polymerase properly, serves as the scaffold for assembly of the MA1-21516 has been successfully used in gel shift, immunoprecipitation, remainder of the transcription complex, and acts as a channel for regulatory and Western blot procedures. signals. TFIID is composed of the TATA-binding protein (TBP) and a group of evolutionarily conserved proteins known as TBP-associated factors or The MA1-21516 immunogen is a synthetic peptide corresponding to the TAFs.
    [Show full text]
  • The Case of Toxic Soluble Dimers of Truncated PQBP-1 Mutants in X-Linked Intellectual Disability
    International Journal of Molecular Sciences Review Fatal Attraction: The Case of Toxic Soluble Dimers of Truncated PQBP-1 Mutants in X-Linked Intellectual Disability Yu Wai Chen 1,2,* and Shah Kamranur Rahman 3 1 Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hunghom 999077, Hong Kong 2 State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hunghom 999077, Hong Kong 3 Department of Infection Biology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK; [email protected] * Correspondence: [email protected] Abstract: The frameshift mutants K192Sfs*7 and R153Sfs*41, of the polyglutamine tract-binding protein 1 (PQBP-1), are stable intrinsically disordered proteins (IDPs). They are each associated with the severe cognitive disorder known as the Renpenning syndrome, a form of X-linked intellectual disability (XLID). Relative to the monomeric wild-type protein, these mutants are dimeric, contain more folded contents, and have higher thermal stabilities. Comparisons can be drawn to the toxic oligomerisation in the “conformational diseases”, which collectively describe medical conditions involving a substantial protein structural transition in the pathogenic mechanism. At the molecular level, the end state of these diseases is often cytotoxic protein aggregation. The conformational disease proteins contain varying extents of intrinsic disorder, and the consensus pathogenesis includes an early oligomer formation. We reviewed the experimental characterisation of the toxic oligomers in representative cases. PQBP-1 mutant dimerisation was then compared to the oligomerisation of Citation: Chen, Y.W.; Rahman, S.K. Fatal Attraction: The Case of Toxic the conformational disease proteins.
    [Show full text]