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Mancinelli C, Marx DC, Gonzalez-Hernandez AJ, Huynh K, Mancinelli L, Arefin A, Khelashvilli G, Levitz J, Eliezer D. Control of G protein-coupled receptor function via membrane-interacting intrinsically disordered C-terminal domains. bioRxiv 2024:2023.08.16.553551. [PMID: 37645938 PMCID: PMC10462050 DOI: 10.1101/2023.08.16.553551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
G protein-coupled receptors (GPCRs) control intracellular signaling cascades via agonist-dependent coupling to intracellular transducers including heterotrimeric G proteins, GPCR kinases (GRKs), and arrestins. In addition to their critical interactions with the transmembrane core of active GPCRs, all three classes of transducers have also been reported to interact with receptor C-terminal domains (CTDs). An underexplored aspect of GPCR CTDs is their possible role as lipid sensors given their proximity to the membrane. CTD-membrane interactions have the potential to control the accessibility of key regulatory CTD residues to downstream effectors and transducers. Here we report that the CTDs of two closely related family C GPCRs, metabotropic glutamate receptor 2 (mGluR2) and mGluR3, bind to membranes and that this interaction can regulate receptor function. We first characterize CTD structure with NMR spectroscopy, revealing lipid composition-dependent modes of membrane binding. Using molecular dynamics simulations and structure-guided mutagenesis, we then identify key conserved residues and cancer-associated mutations that modulate CTD-membrane binding. Finally, we provide evidence that mGluR3 transducer coupling is controlled by CTD-membrane interactions in live cells, which may be subject to regulation by CTD phosphorylation and changes in membrane composition. This work reveals a novel mechanism of GPCR modulation, suggesting that CTD-membrane binding may be a general regulatory mode throughout the broad GPCR superfamily.
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Affiliation(s)
- Chiara Mancinelli
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
- equal contribution
| | - Dagan C. Marx
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
- equal contribution
| | | | - Kevin Huynh
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Lucia Mancinelli
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - Anisul Arefin
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
| | - George Khelashvilli
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
- Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065, USA
| | - David Eliezer
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA
- Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
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2
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Biswas S, Gollub E, Yu F, Ginell G, Holehouse A, Sukenik S, Boothby TC. Helicity of a tardigrade disordered protein contributes to its protective function during desiccation. Protein Sci 2024; 33:e4872. [PMID: 38114424 PMCID: PMC10804681 DOI: 10.1002/pro.4872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/30/2023] [Accepted: 12/12/2023] [Indexed: 12/21/2023]
Abstract
To survive extreme drying (anhydrobiosis), many organisms, spanning every kingdom of life, accumulate intrinsically disordered proteins (IDPs). For decades, the ability of anhydrobiosis-related IDPs to form transient amphipathic helices has been suggested to be important for promoting desiccation tolerance. However, evidence empirically supporting the necessity and/or sufficiency of helicity in mediating anhydrobiosis is lacking. Here, we demonstrate that the linker region of CAHS D, a desiccation-related IDP from the tardigrade Hypsibius exemplaris, that contains significant helical structure, is the protective portion of this protein. Perturbing the sequence composition and grammar of the linker region of CAHS D, through the insertion of helix-breaking prolines, modulating the identity of charged residues, or replacement of hydrophobic amino acids with serine or glycine residues results in variants with different degrees of helical structure. Importantly, correlation of protective capacity and helical content in variants generated through different helix perturbing modalities does not show as strong a trend, suggesting that while helicity is important, it is not the only property that makes a protein protective during desiccation. These results provide direct evidence for the decades-old theory that helicity of desiccation-related IDPs is linked to their anhydrobiotic capacity.
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Affiliation(s)
- Sourav Biswas
- Department of Molecular BiologyUniversity of WyomingLaramieWyomingUSA
| | - Edith Gollub
- Department of Chemistry and BiochemistryUniversity of California, MercedMercedCaliforniaUSA
- Quantitative Systems Biology ProgramUniversity of California MercedMercedCaliforniaUSA
| | - Feng Yu
- Department of Chemistry and BiochemistryUniversity of California, MercedMercedCaliforniaUSA
- Quantitative Systems Biology ProgramUniversity of California MercedMercedCaliforniaUSA
| | - Garrett Ginell
- Department of Biochemistry and Molecular BiophysicsWashington University School of MedicineSt. LouisMissouriUSA
- Center for Biomolecular CondensatesWashington University in St. LouisSt. LouisMissouriUSA
| | - Alex Holehouse
- Department of Biochemistry and Molecular BiophysicsWashington University School of MedicineSt. LouisMissouriUSA
- Center for Biomolecular CondensatesWashington University in St. LouisSt. LouisMissouriUSA
| | - Shahar Sukenik
- Department of Chemistry and BiochemistryUniversity of California, MercedMercedCaliforniaUSA
- Quantitative Systems Biology ProgramUniversity of California MercedMercedCaliforniaUSA
| | - Thomas C. Boothby
- Department of Molecular BiologyUniversity of WyomingLaramieWyomingUSA
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3
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Schröder JM. Discovery of natural bispecific antibodies: Is psoriasis induced by a toxigenic Corynebacterium simulans and maintained by CIDAMPs as autoantigens? Exp Dermatol 2024; 33:e15014. [PMID: 38284202 DOI: 10.1111/exd.15014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/21/2023] [Accepted: 12/29/2023] [Indexed: 01/30/2024]
Abstract
The high abundance of Corynebacterium simulans in psoriasis skin suggests a contribution to the psoriasis aetiology. This hypothesis was tested in an exploratory study, where western blot (WB) analyses with extracts of heat-treated C. simulans and psoriasis serum-derived IgG exhibited a single 16 kDa-WB-band. Proteomic analyses revealed ribosomal proteins as candidate C. s.-antigens. A peptidomic analysis unexpectedly showed that psoriasis serum-derived IgG already contained 31 immunopeptides of Corynebacteria ssp., suggesting the presence of natural bispecific antibodies (BsAbs). Moreover, peptidomic analyses gave 372 DECOY-peptides with similarity to virus- and phage proteins, including Corynebacterium diphtheriae phage, and similarity to diphtheria toxin. Strikingly, a peptidomic analysis for human peptides revealed 64 epitopes of major psoriasis autoantigens such as the spacer region of filaggrin, hornerin repeats and others. Most identified immunopeptides represent potential cationic intrinsically disordered antimicrobial peptides (CIDAMPs), which are generated within the epidermis. These may form complexes with bacterial disordered protein regions, representing chimeric antigens containing discontinuous epitopes. In addition, among 128 low-abundance immunopeptides, 48 are putatively psoriasis-relevant such as epitope peptides of PGE2-, vitamin D3- and IL-10-receptors. Further, 47 immunopeptides originated from tumour antigens, and the endogenous retrovirus HERV-K. I propose that persistent infection with a toxigenic C. simulans initiates psoriasis, which is exacerbated as an autoimmune disease by CIDAMPs as autoantigens. The discovery of natural BsAbs allows the identification of antigen epitopes from microbes, viruses, autoantigens and tumour-antigens, and may help to develop epitope-specific peptide-vaccines and therapeutic approaches with antigen-specific regulatory T cells to improve immune tolerance in an autoimmune disease-specific-manner.
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Affiliation(s)
- Jens-Michael Schröder
- Department of Dermatology, University-Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
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4
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Polyansky AA, Gallego LD, Efremov RG, Köhler A, Zagrovic B. Protein compactness and interaction valency define the architecture of a biomolecular condensate across scales. eLife 2023; 12:e80038. [PMID: 37470705 PMCID: PMC10406433 DOI: 10.7554/elife.80038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/18/2023] [Indexed: 07/21/2023] Open
Abstract
Non-membrane-bound biomolecular condensates have been proposed to represent an important mode of subcellular organization in diverse biological settings. However, the fundamental principles governing the spatial organization and dynamics of condensates at the atomistic level remain unclear. The Saccharomyces cerevisiae Lge1 protein is required for histone H2B ubiquitination and its N-terminal intrinsically disordered fragment (Lge11-80) undergoes robust phase separation. This study connects single- and multi-chain all-atom molecular dynamics simulations of Lge11-80 with the in vitro behavior of Lge11-80 condensates. Analysis of modeled protein-protein interactions elucidates the key determinants of Lge11-80 condensate formation and links configurational entropy, valency, and compactness of proteins inside the condensates. A newly derived analytical formalism, related to colloid fractal cluster formation, describes condensate architecture across length scales as a function of protein valency and compactness. In particular, the formalism provides an atomistically resolved model of Lge11-80 condensates on the scale of hundreds of nanometers starting from individual protein conformers captured in simulations. The simulation-derived fractal dimensions of condensates of Lge11-80 and its mutants agree with their in vitro morphologies. The presented framework enables a multiscale description of biomolecular condensates and embeds their study in a wider context of colloid self-organization.
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Affiliation(s)
- Anton A Polyansky
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational BiologyViennaAustria
| | - Laura D Gallego
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- Medical University of Vienna, Center for Medical BiochemistryViennaAustria
| | - Roman G Efremov
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of SciencesMoscowRussian Federation
| | - Alwin Köhler
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- Medical University of Vienna, Center for Medical BiochemistryViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell BiologyViennaAustria
| | - Bojan Zagrovic
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational BiologyViennaAustria
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Shi B, Matsui T, Qian S, Weiss TM, Nicholl ID, Callaway DJE, Bu Z. An ensemble of cadherin-catenin-vinculin complex employs vinculin as the major F-actin binding mode. Biophys J 2023; 122:2456-2474. [PMID: 37147801 PMCID: PMC10323030 DOI: 10.1016/j.bpj.2023.04.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 02/14/2023] [Accepted: 04/27/2023] [Indexed: 05/07/2023] Open
Abstract
The cell-cell adhesion cadherin-catenin complexes recruit vinculin to the adherens junction (AJ) to modulate the mechanical couplings between neighboring cells. However, it is unclear how vinculin influences the AJ structure and function. Here, we identified two patches of salt bridges that lock vinculin in the head-tail autoinhibited conformation and reconstituted the full-length vinculin activation mimetics bound to the cadherin-catenin complex. The cadherin-catenin-vinculin complex contains multiple disordered linkers and is highly dynamic, which poses a challenge for structural studies. We determined the ensemble conformation of this complex using small-angle x-ray and selective deuteration/contrast variation small-angle neutron scattering. In the complex, both α-catenin and vinculin adopt an ensemble of flexible conformations, but vinculin has fully open conformations with the vinculin head and actin-binding tail domains well separated from each other. F-actin binding experiments show that the cadherin-catenin-vinculin complex binds and bundles F-actin. However, when the vinculin actin-binding domain is removed from the complex, only a minor fraction of the complex binds to F-actin. The results show that the dynamic cadherin-catenin-vinculin complex employs vinculin as the primary F-actin binding mode to strengthen AJ-cytoskeleton interactions.
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Affiliation(s)
- Bright Shi
- Department of Chemistry and Biochemistry, City College of New York, City University of New York (CUNY), New York; PhD Programs in Chemistry and Biochemistry, CUNY Graduate Center, New York
| | - Tsutomu Matsui
- Stanford Synchrotron Radiation Light Source, Menlo Park, California
| | - Shuo Qian
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Thomas M Weiss
- Stanford Synchrotron Radiation Light Source, Menlo Park, California
| | - Iain D Nicholl
- Department of Biomedical Science and Physiology, Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton, United Kingdom
| | - David J E Callaway
- Department of Chemistry and Biochemistry, City College of New York, City University of New York (CUNY), New York.
| | - Zimei Bu
- Department of Chemistry and Biochemistry, City College of New York, City University of New York (CUNY), New York; PhD Programs in Chemistry and Biochemistry, CUNY Graduate Center, New York.
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6
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Jaipuria G, Shet D, Malik S, Swain M, Atreya HS, Galea CA, Slomiany MG, Rosenzweig SA, Forbes BE, Norton RS, Mondal S. IGF-dependent dynamic modulation of a protease cleavage site in the intrinsically disordered linker domain of human IGFBP2. Proteins 2022; 90:1732-1743. [PMID: 35443068 PMCID: PMC9357107 DOI: 10.1002/prot.26350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 03/02/2022] [Accepted: 03/22/2022] [Indexed: 12/29/2022]
Abstract
Functional regulation via conformational dynamics is well known in structured proteins but less well characterized in intrinsically disordered proteins and their complexes. Using NMR spectroscopy, we have identified a dynamic regulatory mechanism in the human insulin-like growth factor (IGF) system involving the central, intrinsically disordered linker domain of human IGF-binding protein-2 (hIGFBP2). The bioavailability of IGFs is regulated by the proteolysis of IGF-binding proteins. In the case of hIGFBP2, the linker domain (L-hIGFBP2) retains its intrinsic disorder upon binding IGF-1, but its dynamics are significantly altered, both in the IGF binding region and distantly located protease cleavage sites. The increase in flexibility of the linker domain upon IGF-1 binding may explain the IGF-dependent modulation of proteolysis of IGFBP2 in this domain. As IGF homeostasis is important for cell growth and function, and its dysregulation is a key contributor to several cancers, our findings open up new avenues for the design of IGFBP analogs inhibiting IGF-dependent tumors.
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Affiliation(s)
- Garima Jaipuria
- NMR Research Centre, Indian Institute of Science, Bangalore-560012, India
| | - Divya Shet
- NMR Research Centre, Indian Institute of Science, Bangalore-560012, India,Nanobiophysics lab, Raman Research Institute, Sadashivnagar, Bangalore-80, India
| | - Shahid Malik
- NMR Research Centre, Indian Institute of Science, Bangalore-560012, India
| | - Monalisa Swain
- NMR Research Centre, Indian Institute of Science, Bangalore-560012, India,Frederick National Laboratory for Cancer Research, Maryland-21701, USA
| | | | - Charles A. Galea
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Parkville 3052, Australia
| | - Mark G. Slomiany
- Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston SC 29425, USA
| | - Steven A. Rosenzweig
- Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston SC 29425, USA
| | - Briony E. Forbes
- Flinders Health and Medical Research Institute, Flinders University, SA 5042, Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Parkville 3052, Australia,ARC Centre for Fragment-Based Design, Monash University, Parkville 3052, Australia
| | - Somnath Mondal
- NMR Research Centre, Indian Institute of Science, Bangalore-560012, India,Univ. Bordeaux, Institut Européen de Chimie et Biologie and INSERM U1212, ARNA Laboratory, 2 rue Robert Escarpit, 33607 Pessac Cedex, Bordeaux, France
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7
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Caspari OD. Transit Peptides Often Require Downstream Unstructured Sequence for Efficient Chloroplast Import in Chlamydomonas reinhardtii. Front Plant Sci 2022; 13:825797. [PMID: 35646025 PMCID: PMC9133816 DOI: 10.3389/fpls.2022.825797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
The N-terminal sequence stretch that defines subcellular targeting for most nuclear encoded chloroplast proteins is usually considered identical to the sequence that is cleaved upon import. Yet here this study shows that for eight out of ten tested Chlamydomonas chloroplast transit peptides, significant additional sequence stretches past the cleavage site are required to enable efficient chloroplast import of heterologous cargo proteins. Analysis of Chlamydomonas cTPs with known cleavage sites and replacements of native post-cleavage residues with alternative sequences points to a role for unstructured sequence at mature protein N-termini.
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8
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Seow J, Das SC, Morales RAV, Ataide R, Krishnarjuna B, Silk M, Chalmers DK, Richards J, Anders RF, MacRaild CA, Norton RS. Guiding the Immune Response to a Conserved Epitope in MSP2, an Intrinsically Disordered Malaria Vaccine Candidate. Vaccines (Basel) 2021; 9:855. [PMID: 34451980 DOI: 10.3390/vaccines9080855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/16/2021] [Accepted: 07/29/2021] [Indexed: 02/06/2023] Open
Abstract
The malaria vaccine candidate merozoite surface protein 2 (MSP2) has shown promise in clinical trials and is in part responsible for a reduction in parasite densities. However, strain-specific reductions in parasitaemia suggested that polymorphic regions of MSP2 are immuno-dominant. One strategy to bypass the hurdle of strain-specificity is to bias the immune response towards the conserved regions. Two mouse monoclonal antibodies, 4D11 and 9H4, recognise the conserved C-terminal region of MSP2. Although they bind overlapping epitopes, 4D11 reacts more strongly with native MSP2, suggesting that its epitope is more accessible on the parasite surface. In this study, a structure-based vaccine design approach was applied to the intrinsically disordered antigen, MSP2, using a crystal structure of 4D11 Fv in complex with its minimal binding epitope. Molecular dynamics simulations and surface plasmon resonance informed the design of a series of constrained peptides that mimicked the 4D11-bound epitope structure. These peptides were conjugated to keyhole limpet hemocyanin and used to immunise mice, with high to moderate antibody titres being generated in all groups. The specificities of antibody responses revealed that a single point mutation can focus the antibody response towards a more favourable epitope. This structure-based approach to peptide vaccine design may be useful not only for MSP2-based malaria vaccines, but also for other intrinsically disordered antigens.
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Saito A, Shofa M, Ode H, Yumiya M, Hirano J, Okamoto T, Yoshimura SH. How Do Flaviviruses Hijack Host Cell Functions by Phase Separation? Viruses 2021; 13:v13081479. [PMID: 34452345 PMCID: PMC8402827 DOI: 10.3390/v13081479] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/21/2021] [Accepted: 07/26/2021] [Indexed: 11/17/2022] Open
Abstract
Viral proteins interact with different sets of host cell components throughout the viral life cycle and are known to localize to the intracellular membraneless organelles (MLOs) of the host cell, where formation/dissolution is regulated by phase separation of intrinsically disordered proteins and regions (IDPs/IDRs). Viral proteins are rich in IDRs, implying that viruses utilize IDRs to regulate phase separation of the host cell organelles and augment replication by commandeering the functions of the organelles and/or sneaking into the organelles to evade the host immune response. This review aims to integrate current knowledge of the structural properties and intracellular localizations of viral IDPs to understand viral strategies in the host cell. First, the properties of viral IDRs are reviewed and similarities and differences with those of eukaryotes are described. The higher IDR content in viruses with smaller genomes suggests that IDRs are essential characteristics of viral proteins. Then, the interactions of the IDRs of flaviviruses with the MLOs of the host cell are investigated with emphasis on the viral proteins localized in the nucleoli and stress granules. Finally, the possible roles of viral IDRs in regulation of the phase separation of organelles and future possibilities for antiviral drug development are discussed.
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Affiliation(s)
- Akatsuki Saito
- Department of Veterinary Science, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan;
- Center for Animal Disease Control, University of Miyazaki, Miyazaki 889-2192, Japan
- Graduate School of Medicine and Veterinary Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
- Correspondence: (A.S.); (T.O.); (S.H.Y.)
| | - Maya Shofa
- Department of Veterinary Science, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan;
- Graduate School of Medicine and Veterinary Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | - Hirotaka Ode
- Clinical Research Center, National Hospital Organization Nagoya Medical Center, Nagoya 460-0001, Japan;
| | - Maho Yumiya
- Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; (M.Y.); (J.H.)
| | - Junki Hirano
- Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; (M.Y.); (J.H.)
| | - Toru Okamoto
- Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; (M.Y.); (J.H.)
- Center for Infectious Diseases Education and Research, Osaka University, Osaka 565-0871, Japan
- Correspondence: (A.S.); (T.O.); (S.H.Y.)
| | - Shige H. Yoshimura
- Laboratory of Plasma Membrane and Nuclear Signaling, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
- Correspondence: (A.S.); (T.O.); (S.H.Y.)
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10
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Zhou Q, Usluer S, Zhang F, Lenard AJ, Bourgeois BMR, Madl T. ATP regulates RNA-driven cold inducible RNA binding protein phase separation. Protein Sci 2021; 30:1438-1453. [PMID: 33991007 PMCID: PMC8197425 DOI: 10.1002/pro.4123] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 01/12/2023]
Abstract
Intrinsically disordered proteins and proteins containing intrinsically disordered regions are highly abundant in the proteome of eukaryotes and are extensively involved in essential biological functions. More recently, their role in the organization of biomolecular condensates has become evident and along with their misregulation in several neurologic disorders. Currently, most studies involving these proteins are carried out in vitro and using purified proteins. Given that in cells, condensate‐forming proteins are exposed to high, millimolar concentrations of cellular metabolites, we aimed to reveal the interactions of cellular metabolites and a representative condensate‐forming protein. Here, using the arginine–glycine/arginine–glycine–glycine (RG/RGG)‐rich cold inducible RNA binding protein (CIRBP) as paradigm, we studied binding of the cellular metabolome to CIRBP. We found that most of the highly abundant cellular metabolites, except nucleotides, do not directly bind to CIRBP. ATP, ADP, and AMP as well as NAD+, NADH, NADP+, and NADPH directly interact with CIRBP, involving both the folded RNA‐recognition motif and the disordered RG/RGG region. ATP binding inhibited RNA‐driven phase separation of CIRBP. Thus, it might be beneficial to include cellular metabolites in in vitro liquid–liquid phase separation studies of RG/RGG and other condensate‐forming proteins in order to better mimic the cellular environment in the future.
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Affiliation(s)
- Qishun Zhou
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology & Biochemistry, Medical University of Graz, Graz, Austria
| | - Sinem Usluer
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology & Biochemistry, Medical University of Graz, Graz, Austria
| | - Fangrong Zhang
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology & Biochemistry, Medical University of Graz, Graz, Austria
| | - Aneta J Lenard
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology & Biochemistry, Medical University of Graz, Graz, Austria
| | - Benjamin M R Bourgeois
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology & Biochemistry, Medical University of Graz, Graz, Austria
| | - Tobias Madl
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology & Biochemistry, Medical University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
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11
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Ardehali MB, Damle M, Perea-Resa C, Blower MD, Kingston RE. Elongin A associates with actively transcribed genes and modulates enhancer RNA levels with limited impact on transcription elongation rate in vivo. J Biol Chem 2020; 296:100202. [PMID: 33334895 PMCID: PMC7948453 DOI: 10.1074/jbc.ra120.015877] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 12/06/2020] [Accepted: 12/16/2020] [Indexed: 01/08/2023] Open
Abstract
Elongin A (EloA) is an essential transcription factor that stimulates the rate of RNA polymerase II (Pol II) transcription elongation in vitro. However, its role as a transcription factor in vivo has remained underexplored. Here we show that in mouse embryonic stem cells, EloA localizes to both thousands of Pol II transcribed genes with preference for transcription start site and promoter regions and a large number of active enhancers across the genome. EloA deletion results in accumulation of transcripts from a subset of enhancers and their adjacent genes. Notably, EloA does not substantially enhance the elongation rate of Pol II in vivo. We also show that EloA localizes to the nucleoli and associates with RNA polymerase I transcribed ribosomal RNA gene, Rn45s. EloA is a highly disordered protein, which we demonstrate forms phase-separated condensates in vitro, and truncation mutations in the intrinsically disordered regions (IDR) of EloA interfere with its targeting and localization to the nucleoli. We conclude that EloA broadly associates with transcribed regions, tunes RNA Pol II transcription levels via impacts on enhancer RNA synthesis, and interacts with the rRNA producing/processing machinery in the nucleolus. Our work opens new avenues for further investigation of the role of this functionally multifaceted transcription factor in enhancer and ribosomal RNA biology.
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Affiliation(s)
- M Behfar Ardehali
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Manashree Damle
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Carlos Perea-Resa
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Michael D Blower
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Robert E Kingston
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
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12
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Abstract
Disordered proteins often act as interaction hubs in cellular pathways, via the specific recognition of a distinguished set of partners. While disordered regions can adopt a well-defined conformation upon binding, the coupled folding to binding model does not explain how interaction versatility is achieved. Here, I present a classification scheme for the binding modes of disordered protein regions, based on their conformational heterogeneity in the bound state. Binding modes are defined as (i) disorder-to-order transitions leading to a well-defined bound state, (ii) disordered binding leading to a disordered bound state and (iii) fuzzy binding when the degree of disorder in the bound state may vary with the partner or cellular conditions. Fuzzy binding includes polymorphic bound structures, conditional folding and dynamic binding. This classification scheme describes the structural continuum of complexes involving disordered regions as well as their context-dependent interaction behaviors.
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Affiliation(s)
- Monika Fuxreiter
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy;
- Laboratory of Protein Dynamics, University of Debrecen, 4032 Debrecen, Hungary
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13
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Reinharz V, Tlusty T. αβDCA method identifies unspecific binding but specific disruption of the group I intron by the StpA chaperone. RNA 2020; 26:1530-1540. [PMID: 32747608 PMCID: PMC7566574 DOI: 10.1261/rna.074336.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 07/19/2020] [Indexed: 06/11/2023]
Abstract
Chaperone proteins-the most disordered among all protein groups-help RNAs fold into their functional structure by destabilizing misfolded configurations or stabilizing the functional ones. But disentangling the mechanism underlying RNA chaperoning is challenging, mostly because of inherent disorder of the chaperones and the transient nature of their interactions with RNA. In particular, it is unclear how specific the interactions are and what role is played by amino acid charge and polarity patterns. Here, we address these questions in the RNA chaperone StpA. We adapted direct coupling analysis (DCA) into the αβDCA method that can treat in tandem sequences written in two alphabets, nucleotides and amino acids. With αβDCA, we could analyze StpA-RNA interactions and show consistency with a previously proposed two-pronged mechanism: StpA disrupts specific positions in the group I intron while globally and loosely binding to the entire structure. Moreover, the interactions are strongly associated with the charge pattern: Negatively charged regions in the destabilizing StpA amino-terminal affect a few specific positions in the RNA, located in stems and in the pseudoknot. In contrast, positive regions in the carboxy-terminal contain strongly coupled amino acids that promote nonspecific or weakly specific binding to the RNA. The present study opens new avenues to examine the functions of disordered proteins and to design disruptive proteins based on their charge patterns.
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Affiliation(s)
- Vladimir Reinharz
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan 44919, Republic of Korea
- Department of Computer Science, Université du Québec à Montréal, Montréal, H2X 3Y7, Canada
| | - Tsvi Tlusty
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan 44919, Republic of Korea
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
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14
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Parker BW, Goncz EJ, Krist DT, Statsyuk AV, Nesvizhskii AI, Weiss EL. Mapping low-affinity/high-specificity peptide-protein interactions using ligand-footprinting mass spectrometry. Proc Natl Acad Sci U S A 2019; 116:21001-11. [PMID: 31578253 DOI: 10.1073/pnas.1819533116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Short linear peptide motifs that are intracellular ligands of folded proteins are a modular, incompletely understood molecular interaction language in signaling systems. Such motifs, which frequently occur in intrinsically disordered protein regions, often bind partner proteins with modest affinity and are difficult to study with conventional structural biology methods. We developed LiF-MS (ligand-footprinting mass spectrometry), a method to map peptide binding sites on folded protein domains that allows consideration of their dynamic disorder, and used it to analyze a set of D-motif peptide-mitogen-activated protein kinase (MAPK) associations to validate the approach and define unknown binding structures. LiF-MS peptide ligands carry a short-lived, indiscriminately reactive cleavable crosslinker that marks contacts close to ligand binding sites with high specificity. Each marked amino acid provides an independent constraint for a set of directed peptide-protein docking simulations, which are analyzed by agglomerative hierarchical clustering. We found that LiF-MS provides accurate ab initio identification of ligand binding surfaces and a view of potential binding ensembles of a set of D-motif peptide-MAPK associations. Our analysis provides an MKK4-JNK1 structural model, which has thus far been crystallographically unattainable, a potential alternate binding mode for part of the NFAT4-JNK interaction, and evidence of bidirectional association of MKK4 peptide with ERK2. Overall, we find that LiF-MS is an effective noncrystallographic way to understand how short linear motifs associate with specific sites on folded protein domains at the level of individual amino acids.
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15
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Ciemny MP, Badaczewska-Dawid AE, Pikuzinska M, Kolinski A, Kmiecik S. Modeling of Disordered Protein Structures Using Monte Carlo Simulations and Knowledge-Based Statistical Force Fields. Int J Mol Sci 2019; 20:E606. [PMID: 30708941 PMCID: PMC6386871 DOI: 10.3390/ijms20030606] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/23/2019] [Accepted: 01/29/2019] [Indexed: 12/20/2022] Open
Abstract
The description of protein disordered states is important for understanding protein folding mechanisms and their functions. In this short review, we briefly describe a simulation approach to modeling protein interactions, which involve disordered peptide partners or intrinsically disordered protein regions, and unfolded states of globular proteins. It is based on the CABS coarse-grained protein model that uses a Monte Carlo (MC) sampling scheme and a knowledge-based statistical force field. We review several case studies showing that description of protein disordered states resulting from CABS simulations is consistent with experimental data. The case studies comprise investigations of protein⁻peptide binding and protein folding processes. The CABS model has been recently made available as the simulation engine of multiscale modeling tools enabling studies of protein⁻peptide docking and protein flexibility. Those tools offer customization of the modeling process, driving the conformational search using distance restraints, reconstruction of selected models to all-atom resolution, and simulation of large protein systems in a reasonable computational time. Therefore, CABS can be combined in integrative modeling pipelines incorporating experimental data and other modeling tools of various resolution.
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Affiliation(s)
- Maciej Pawel Ciemny
- Faculty of Chemistry, Biological and Chemical Research Center, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland.
| | | | - Monika Pikuzinska
- Faculty of Chemistry, Biological and Chemical Research Center, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
| | - Andrzej Kolinski
- Faculty of Chemistry, Biological and Chemical Research Center, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
| | - Sebastian Kmiecik
- Faculty of Chemistry, Biological and Chemical Research Center, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
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16
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Neira JL, Giudici AM, Hornos F, Arbe A, Rizzuti B. The C Terminus of the Ribosomal-Associated Protein LrtA Is an Intrinsically Disordered Oligomer. Int J Mol Sci 2018; 19:E3902. [PMID: 30563168 DOI: 10.3390/ijms19123902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 11/28/2018] [Accepted: 12/02/2018] [Indexed: 01/01/2023] Open
Abstract
The 191-residue-long LrtA protein of Synechocystis sp. PCC 6803 is involved in post-stress survival and in stabilizing 70S ribosomal particles. It belongs to the hibernating promoting factor (HPF) family, intervening in protein synthesis. The protein consists of two domains: The N-terminal region (N-LrtA, residues 1–101), which is common to all the members of the HPF, and seems to be well-folded; and the C-terminal region (C-LrtA, residues 102–191), which is hypothesized to be disordered. In this work, we studied the conformational preferences of isolated C-LrtA in solution. The protein was disordered, as shown by computational modelling, 1D-1H NMR, steady-state far-UV circular dichroism (CD) and chemical and thermal denaturations followed by fluorescence and far-UV CD. Moreover, at physiological conditions, as indicated by several biochemical and hydrodynamic techniques, isolated C-LrtA intervened in a self-association equilibrium, involving several oligomerization reactions. Thus, C-LrtA was an oligomeric disordered protein.
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17
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Pancsa R, Zsolyomi F, Tompa P. Co-Evolution of Intrinsically Disordered Proteins with Folded Partners Witnessed by Evolutionary Couplings. Int J Mol Sci 2018; 19:E3315. [PMID: 30366362 DOI: 10.3390/ijms19113315] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 10/19/2018] [Accepted: 10/22/2018] [Indexed: 12/22/2022] Open
Abstract
Although improved strategies for the detection and analysis of evolutionary couplings (ECs) between protein residues already enable the prediction of protein structures and interactions, they are mostly restricted to conserved and well-folded proteins. Whereas intrinsically disordered proteins (IDPs) are central to cellular interaction networks, due to the lack of strict structural constraints, they undergo faster evolutionary changes than folded domains. This makes the reliable identification and alignment of IDP homologs difficult, which led to IDPs being omitted in most large-scale residue co-variation analyses. By preforming a dedicated analysis of phylogenetically widespread bacterial IDP–partner interactions, here we demonstrate that partner binding imposes constraints on IDP sequences that manifest in detectable interprotein ECs. These ECs were not detected for interactions mediated by short motifs, rather for those with larger IDP–partner interfaces. Most identified coupled residue pairs reside close (<10 Å) to each other on the interface, with a third of them forming multiple direct atomic contacts. EC-carrying interfaces of IDPs are enriched in negatively charged residues, and the EC residues of both IDPs and partners preferentially reside in helices. Our analysis brings hope that IDP–partner interactions difficult to study could soon be successfully dissected through residue co-variation analysis.
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18
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Abstract
Protein folding poses unique challenges for large, disordered proteins due to the low resolution of structural data accessible in experiment and on the basis of short time scales and limited sampling attainable in computation. Such molecules are uniquely suited to accelerated-sampling molecular dynamics algorithms due to a flat-energy landscape. We apply these methods to report here the folded structure in water from a fully extended chain of tropoelastin, a 698-amino acid molecular precursor to elastic fibers that confer elasticity and recoil to tissues, finding good agreement with experimental data. We then study a series of artificial and disease-related mutations, yielding molecular mechanisms to explain structural differences and variation in hierarchical assembly observed in experiment. The present model builds a framework for studying assembly and disease and yields critical insight into molecular mechanisms behind these processes. These results suggest that proteins with disordered regions are suitable candidates for characterization by this approach.
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Affiliation(s)
- Anna Tarakanova
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 01239
| | - Giselle C Yeo
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
| | - Clair Baldock
- Wellcome Trust Centre for Cell-Matrix Research, Division of Cell Matrix Biology and Regenerative Medicine, School of Biological Sciences, Manchester Academic Health Science Centre, The University of Manchester, Manchester M13 9PT, United Kingdom
| | - Anthony S Weiss
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia
- Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 01239;
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19
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Contreras LM, Sevilla P, Cámara-Artigas A, Hernández-Cifre JG, Rizzuti B, Florencio FJ, Muro-Pastor MI, García de la Torre J, Neira JL. The Cyanobacterial Ribosomal-Associated Protein LrtA from Synechocystis sp. PCC 6803 Is an Oligomeric Protein in Solution with Chameleonic Sequence Properties. Int J Mol Sci 2018; 19:ijms19071857. [PMID: 29937518 PMCID: PMC6073757 DOI: 10.3390/ijms19071857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/18/2018] [Accepted: 06/20/2018] [Indexed: 12/25/2022] Open
Abstract
The LrtA protein of Synechocystis sp. PCC 6803 intervenes in cyanobacterial post-stress survival and in stabilizing 70S ribosomal particles. It belongs to the hibernating promoting factor (HPF) family of proteins, involved in protein synthesis. In this work, we studied the conformational preferences and stability of isolated LrtA in solution. At physiological conditions, as shown by hydrodynamic techniques, LrtA was involved in a self-association equilibrium. As indicated by Nuclear Magnetic Resonance (NMR), circular dichroism (CD) and fluorescence, the protein acquired a folded, native-like conformation between pH 6.0 and 9.0. However, that conformation was not very stable, as suggested by thermal and chemical denaturations followed by CD and fluorescence. Theoretical studies of its highly-charged sequence suggest that LrtA had a Janus sequence, with a context-dependent fold. Our modelling and molecular dynamics (MD) simulations indicate that the protein adopted the same fold observed in other members of the HPF family (β-α-β-β-β-α) at its N-terminal region (residues 1–100), whereas the C terminus (residues 100–197) appeared disordered and collapsed, supporting the overall percentage of overall secondary structure obtained by CD deconvolution. Then, LrtA has a chameleonic sequence and it is the first member of the HPF family involved in a self-association equilibrium, when isolated in solution.
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Affiliation(s)
- Lellys M Contreras
- Center for Environmental Biology and Chemistry Research, Facultad Experimental de Ciencias y Tecnología, Universidad de Carabobo, 2001 Valencia, Venezuela.
| | - Paz Sevilla
- Facultad de Farmacia, Departamento de Química Física II, Universidad Complutense de Madrid, 28040 Madrid, Spain.
- Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid, Spain.
| | - Ana Cámara-Artigas
- Department of Chemistry and Physics, Research Centre CIAIMBITAL, University of Almería- ceiA3, 04120 Almería, Spain.
| | | | - Bruno Rizzuti
- CNR-NANOTEC, Licryl-UOS Cosenza and CEMIF.Cal, Department of Physics, University of Calabria, 87036 Rende, Italy.
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, 41092 Seville, Spain.
| | - María Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, 41092 Seville, Spain.
| | | | - José L Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain.
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain.
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20
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Csizmok V, Montecchio M, Lin H, Tyers M, Sunnerhagen M, Forman-Kay JD. Multivalent Interactions with Fbw7 and Pin1 Facilitate Recognition of c-Jun by the SCF Fbw7 Ubiquitin Ligase. Structure 2017; 26:28-39.e2. [PMID: 29225075 DOI: 10.1016/j.str.2017.11.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/07/2017] [Accepted: 11/08/2017] [Indexed: 01/09/2023]
Abstract
Many regulatory proteins, including the transcription factor c-Jun, are highly enriched in disordered protein regions that govern growth, division, survival, differentiation, and response to signals. The stability of c-Jun is controlled by poorly understood regulatory interactions of its disordered region with both the E3 ubiquitin ligase SCFFbw7 and prolyl cis-trans isomerase Pin1. We use nuclear magnetic resonance and fluorescence studies of c-Jun to demonstrate that multisite c-Jun phosphorylation is required for high-affinity interaction with Fbw7. We show that the Pin1 WW and PPIase domains interact in a dynamic complex with multiply phosphorylated c-Jun. Importantly, Pin1 isomerizes a pSer-Pro peptide bond at the c-Jun N terminus that affects binding to Fbw7 and thus modulates the ubiquitin-mediated degradation of c-Jun. Our findings support the general principle that multiple weak binding motifs within disordered regions can synergize to yield high-affinity interactions and provide rapidly evolvable means to build and fine-tune regulatory events.
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Affiliation(s)
- Veronika Csizmok
- Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Meri Montecchio
- Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden
| | - Hong Lin
- Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Mike Tyers
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Maria Sunnerhagen
- Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden
| | - Julie D Forman-Kay
- Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
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21
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Callaway DJE, Matsui T, Weiss T, Stingaciu LR, Stanley CB, Heller WT, Bu Z. Controllable Activation of Nanoscale Dynamics in a Disordered Protein Alters Binding Kinetics. J Mol Biol 2017; 429:987-998. [PMID: 28285124 DOI: 10.1016/j.jmb.2017.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 02/04/2017] [Accepted: 03/02/2017] [Indexed: 01/03/2023]
Abstract
The phosphorylation of specific residues in a flexible disordered activation loop yields precise control of signal transduction. One paradigm is the phosphorylation of S339/S340 in the intrinsically disordered tail of the multi-domain scaffolding protein NHERF1, which affects the intracellular localization and trafficking of NHERF1 assembled signaling complexes. Using neutron spin echo spectroscopy (NSE), we show salt-concentration-dependent excitation of nanoscale motion at the tip of the C-terminal tail in the phosphomimic S339D/S340D mutant. The "tip of the whip" that is unleashed is near the S339/S340 phosphorylation site and flanks the hydrophobic Ezrin-binding motif. The kinetic association rate constant of the binding of the S339D/S340D mutant to the FERM domain of Ezrin is sensitive to buffer salt concentration, correlating with the excited nanoscale dynamics. The results suggest that electrostatics modulates the activation of nanoscale dynamics of an intrinsically disordered protein, controlling the binding kinetics of signaling partners. NSE can pinpoint the nanoscale dynamics changes in a highly specific manner.
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Affiliation(s)
- David J E Callaway
- Department of Chemistry and Biochemistry, City College of New York, CUNY, New York, NY 10031, USA.
| | - Tsutomu Matsui
- Stanford Synchrotron Radiation Light Source, Menlo Park, CA 94025, USA
| | - Thomas Weiss
- Stanford Synchrotron Radiation Light Source, Menlo Park, CA 94025, USA
| | - Laura R Stingaciu
- Jülich Centre for Neutron Science JCNS, Forschungszentrum Jülich GmbH, Outstation at SNS, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Christopher B Stanley
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - William T Heller
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Zimei Bu
- Department of Chemistry and Biochemistry, City College of New York, CUNY, New York, NY 10031, USA.
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22
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Seow J, Morales RAV, MacRaild CA, Krishnarjuna B, McGowan S, Dingjan T, Jaipuria G, Rouet R, Wilde KL, Atreya HS, Richards JS, Anders RF, Christ D, Drinkwater N, Norton RS. Structure and Characterisation of a Key Epitope in the Conserved C-Terminal Domain of the Malaria Vaccine Candidate MSP2. J Mol Biol 2017; 429:836-846. [PMID: 28189425 DOI: 10.1016/j.jmb.2017.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/22/2017] [Accepted: 02/05/2017] [Indexed: 10/20/2022]
Abstract
Merozoite surface protein 2 (MSP2) is an intrinsically disordered antigen that is abundant on the surface of the malaria parasite Plasmodium falciparum. The two allelic families of MSP2, 3D7 and FC27, differ in their central variable regions, which are flanked by highly conserved C-terminal and N-terminal regions. In a vaccine trial, full-length 3D7 MSP2 induced a strain-specific protective immune response despite the detectable presence of conserved region antibodies. This work focuses on the conserved C-terminal region of MSP2, which includes the only disulphide bond in the protein and encompasses key epitopes recognised by the mouse monoclonal antibodies 4D11 and 9H4. Although the 4D11 and 9H4 epitopes are overlapping, immunofluorescence assays have shown that the mouse monoclonal antibody 4D11 binds to MSP2 on the merozoite surface with a much stronger signal than 9H4. Understanding the structural basis for this antigenic difference between these antibodies will help direct the design of a broad-spectrum and MSP2-based malaria vaccine. 4D11 and 9H4 were reengineered into antibody fragments [variable region fragment (Fv) and single-chain Fv (scFv)] and were validated as suitable models for their full-sized IgG counterparts by surface plasmon resonance and isothermal titration calorimetry. An alanine scan of the 13-residue epitope 3D7-MSP2207-222 identified the minimal binding epitope of 4D11 and the key residues involved in binding. A 2.2-Å crystal structure of 4D11 Fv bound to the eight-residue epitope NKENCGAA provided valuable insight into the possible conformation of the C-terminal region of MSP2 on the parasite. This work underpins continued efforts to optimise recombinant MSP2 constructs for evaluation as potential vaccine candidates.
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Affiliation(s)
- Jeffrey Seow
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia
| | - Rodrigo A V Morales
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia
| | - Christopher A MacRaild
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia
| | - Bankala Krishnarjuna
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia
| | - Sheena McGowan
- Department of Microbiology, Monash University, Clayton 3168, Australia
| | - Tamir Dingjan
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia
| | - Garima Jaipuria
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Romain Rouet
- Garvan Institute of Medical Research, Darlinghurst 2010, Australia
| | - Karyn L Wilde
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Lucas Heights 2234, Australia
| | - Hanudatta S Atreya
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India
| | - Jack S Richards
- Centre for Biomedical Research, The Burnet Institute, Melbourne 3004, Australia
| | - Robin F Anders
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3086, Australia
| | - Daniel Christ
- Garvan Institute of Medical Research, Darlinghurst 2010, Australia
| | - Nyssa Drinkwater
- Department of Microbiology, Monash University, Clayton 3168, Australia
| | - Raymond S Norton
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia.
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23
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Stevers LM, Lam CV, Leysen SF, Meijer FA, van Scheppingen DS, de Vries RM, Carlile GW, Milroy LG, Thomas DY, Brunsveld L, Ottmann C. Characterization and small-molecule stabilization of the multisite tandem binding between 14-3-3 and the R domain of CFTR. Proc Natl Acad Sci U S A 2016; 113:E1152-61. [PMID: 26888287 DOI: 10.1073/pnas.1516631113] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Cystic fibrosis is a fatal genetic disease, most frequently caused by the retention of the CFTR (cystic fibrosis transmembrane conductance regulator) mutant protein in the endoplasmic reticulum (ER). The binding of the 14-3-3 protein to the CFTR regulatory (R) domain has been found to enhance CFTR trafficking to the plasma membrane. To define the mechanism of action of this protein-protein interaction, we have examined the interaction in vitro. The disordered multiphosphorylated R domain contains nine different 14-3-3 binding motifs. Furthermore, the 14-3-3 protein forms a dimer containing two amphipathic grooves that can potentially bind these phosphorylated motifs. This results in a number of possible binding mechanisms between these two proteins. Using multiple biochemical assays and crystal structures, we show that the interaction between them is governed by two binding sites: The key binding site of CFTR (pS768) occupies one groove of the 14-3-3 dimer, and a weaker, secondary binding site occupies the other binding groove. We show that fusicoccin-A, a natural-product tool compound used in studies of 14-3-3 biology, can stabilize the interaction between 14-3-3 and CFTR by selectively interacting with a secondary binding motif of CFTR (pS753). The stabilization of this interaction stimulates the trafficking of mutant CFTR to the plasma membrane. This definition of the druggability of the 14-3-3-CFTR interface might offer an approach for cystic fibrosis therapeutics.
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24
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Iwashita S, Suzuki T, Yasuda T, Nakashima K, Sakamoto T, Kohno T, Takahashi I, Kobayashi T, Ohno-Iwashita Y, Imajoh-Ohmi S, Song SY, Dohmae N. Mammalian Bcnt/Cfdp1, a potential epigenetic factor characterized by an acidic stretch in the disordered N-terminal and Ser250 phosphorylation in the conserved C-terminal regions. Biosci Rep 2015; 35:e00228. [PMID: 26182435 DOI: 10.1042/BSR20150111] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/01/2015] [Indexed: 12/19/2022] Open
Abstract
We characterized the mammalian Bcnt/Cfdp1 (Bucentaur/craniofacial developmental protein 1) protein, a potential epigenetic factor, by showing that an acidic stretch in the N-terminal region and Ser250 phosphorylation in the C-terminal region are critical for its anomalous SDS/PAGE mobility. The BCNT (Bucentaur) superfamily is classified by an uncharacteristic conserved sequence of ∼80 amino acids (aa) at the C-terminus, BCNT-C (the conserved C-terminal region of Bcnt/Cfdp1). Whereas the yeast Swc5 and Drosophila Yeti homologues play crucial roles in chromatin remodelling organization, mammalian Bcnt/Cfdp1 (craniofacial developmental protein 1) remains poorly understood. The protein, which lacks cysteine, is largely disordered and comprises an acidic N-terminal region, a lysine/glutamic acid/proline-rich 40 aa sequence and BCNT-C. It shows complex mobility on SDS/PAGE at ∼50 kDa, whereas its calculated molecular mass is ∼33 kDa. To characterize this mobility discrepancy and the effects of post-translational modifications (PTMs), we expressed various deleted His–Bcnt in E. coli and HEK cells and found that an acidic stretch in the N-terminal region is a main cause of the gel shift. Exogenous BCNT/CFDP1 constitutively expressed in HEK clones appears as a doublet at 49 and 47 kDa, slower than the protein expressed in Escherichia coli but faster than the endogenous protein on SDS/PAGE. Among seven in vivo phosphorylation sites, Ser250, which resides in a region between disordered and ordered regions in BCNT-C, is heavily phosphorylated and detected predominantly in the 49 kDa band. Together with experiments involving treatment with phosphatases and Ser250 substitutions, the results indicate that the complex behaviour of Bcnt/Cfdp1 on SDS/PAGE is caused mainly by an acidic stretch in the N-terminal region and Ser250 phosphorylation in BCNT-C. Furthermore, Bcnt/Cfdp1 is acetylated in vitro by CREB-binding protein (CBP) and four lysine residues including Lys268 in BCNT-C are also acetylated in vivo, revealing a protein regulated at multiple levels.
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Petrlova J, Bhattacherjee A, Boomsma W, Wallin S, Lagerstedt JO, Irbäck A. Conformational and aggregation properties of the 1-93 fragment of apolipoprotein A-I. Protein Sci 2014; 23:1559-71. [PMID: 25131953 DOI: 10.1002/pro.2534] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/11/2014] [Accepted: 08/04/2014] [Indexed: 11/12/2022]
Abstract
Several disease-linked mutations of apolipoprotein A-I, the major protein in high-density lipoprotein (HDL), are known to be amyloidogenic, and the fibrils often contain N-terminal fragments of the protein. Here, we present a combined computational and experimental study of the fibril-associated disordered 1-93 fragment of this protein, in wild-type and mutated (G26R, S36A, K40L, W50R) forms. In atomic-level Monte Carlo simulations of the free monomer, validated by circular dichroism spectroscopy, we observe changes in the position-dependent β-strand probability induced by mutations. We find that these conformational shifts match well with the effects of these mutations in thioflavin T fluorescence and transmission electron microscopy experiments. Together, our results point to molecular mechanisms that may have a key role in disease-linked aggregation of apolipoprotein A-I.
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Affiliation(s)
- Jitka Petrlova
- Department of Experimental Medical Science, Lund University, BMC Floor C12, SE-221 84, Lund, Sweden
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Li M, Cho SB, Ryu KH. A novel approach for predicting disordered regions in a protein sequence. Osong Public Health Res Perspect 2014; 5:211-8. [PMID: 25379372 PMCID: PMC4215001 DOI: 10.1016/j.phrp.2014.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 06/24/2014] [Accepted: 06/24/2014] [Indexed: 12/01/2022] Open
Abstract
OBJECTIVES A number of published predictors are based on various algorithms and disordered protein sequence properties. Although many predictors have been published, the study of protein disordered region prediction is ongoing because different prediction methods can find different disordered regions in a protein sequence. METHODS Therefore we have used a new approach to find the more varying disordered regions for more efficient and accurate prediction of protein structures. In this study, we propose a novel approach called "emerging subsequence (ES) mining" without using the characteristics of the disordered protein. We first adapted the approach to generate emerging protein subsequences on public protein sequence data. Second, the disordered and ordered regions in a protein sequence were predicted by searching the generated emerging protein subsequence with a sliding window, which tends to overlap. Third, the scores of the overlapping regions were calculated based on support and growthrate values in both classes. Finally, the score of predicted regions in the target class were compared with the score of the source class, and the class having a higher score was selected. RESULTS In this experiment, disordered sequence data and ordered sequence data was extracted from DisProt 6.02 and PDB respectively and used as training data. The test data come from CASP 9 and CASP 10 where disordered and ordered regions are known. CONCLUSION Comparing with several published predictors, the results of the experiment show higher accuracy rates than with other existing methods.
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Affiliation(s)
- Meijing Li
- Database/Bioinformatics Laboratory, Chungbuk National University, Cheongju, Korea
| | - Seong Beom Cho
- Division of Bio-Medical Informatics, Center for Genome Science, Korea National Institute of Health, Cheongju, Korea
| | - Keun Ho Ryu
- Database/Bioinformatics Laboratory, Chungbuk National University, Cheongju, Korea
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Hara M, Kondo M, Kato T. A KS-type dehydrin and its related domains reduce Cu-promoted radical generation and the histidine residues contribute to the radical-reducing activities. J Exp Bot 2013; 64:1615-24. [PMID: 23382551 PMCID: PMC3617826 DOI: 10.1093/jxb/ert016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Dehydrin is a plant disordered protein whose functions are not yet totally understood. Here it is reported that a KS-type dehydrin can reduce the formation of reactive oxygen species (ROS) from Cu. AtHIRD11, which is the Arabidopsis KS-type dehydrin, inhibited generation of hydrogen peroxide and hydroxyl radicals in the Cu-ascorbate system. The radical-reducing activity of AtHIRD11 was stronger than those of radical-silencing peptides such as glutathione and serum albumin. The addition of Cu(2+) reduced the disordered state, decreased the trypsin susceptibility, and promoted the self-association of AtHIRD11. Domain analyses indicated that the five domains containing histidine showed ROS-reducing activities. Histidine/alanine substitutions indicated that histidine is a crucial residue for reducing ROS generation. Using the 27 peptides which are related to the KnS-type dehydrins of 14 plant species, it was found that the strengths of ROS-reducing activities can be determined by two factors, namely the histidine contents and the length of the peptides. The degree of ROS-reducing activities of a dehydrin can be predicted using these indices.
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Affiliation(s)
- Masakazu Hara
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan.
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Tagliazucchi M, Peleg O, Kröger M, Rabin Y, Szleifer I. Effect of charge, hydrophobicity, and sequence of nucleoporins on the translocation of model particles through the nuclear pore complex. Proc Natl Acad Sci U S A 2013; 110:3363-8. [PMID: 23404701 PMCID: PMC3587244 DOI: 10.1073/pnas.1212909110] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The molecular structure of the yeast nuclear pore complex (NPC) and the translocation of model particles have been studied with a molecular theory that accounts for the geometry of the pore and the sequence and anchoring position of the unfolded domains of the nucleoporin proteins (the FG-Nups), which control selective transport through the pore. The theory explicitly models the electrostatic, hydrophobic, steric, conformational, and acid-base properties of the FG-Nups. The electrostatic potential within the pore, which arises from the specific charge distribution of the FG-Nups, is predicted to be negative close to pore walls and positive along the pore axis. The positive electrostatic potential facilitates the translocation of negatively charged particles, and the free energy barrier for translocation decreases for increasing particle hydrophobicity. These results agree with the experimental observation that transport receptors that form complexes with hydrophilic/neutral or positively charged proteins to transport them through the NPC are both hydrophobic and strongly negatively charged. The molecular theory shows that the effects of electrostatic and hydrophobic interactions on the translocating potential are cooperative and nonequivalent due to the interaction-dependent reorganization of the FG-Nups in the presence of the translocating particle. The combination of electrostatic and hydrophobic interactions can give rise to complex translocation potentials displaying a combination of wells and barriers, in contrast to the simple barrier potential observed for a hydrophilic/neutral translocating particle. This work demonstrates the importance of explicitly considering the amino acid sequence and hydrophobic, electrostatic, and steric interactions in understanding the translocation through the NPC.
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Affiliation(s)
- Mario Tagliazucchi
- Department of Biomedical Engineering, Department of Chemistry, and Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208
| | - Orit Peleg
- Institute for Neuroinformatics, University of Zurich and Eidgenössische Technische Hochschule Zurich, 8057 Zurich, Switzerland
| | - Martin Kröger
- Polymer Physics, Department of Materials, Eidgenössische Technische Hochschule Zurich, 8093 Zurich, Switzerland; and
| | - Yitzhak Rabin
- Department of Physics and Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Igal Szleifer
- Department of Biomedical Engineering, Department of Chemistry, and Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208
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Sibille N, Huvent I, Fauquant C, Verdegem D, Amniai L, Leroy A, Wieruszeski JM, Lippens G, Landrieu I. Structural characterization by nuclear magnetic resonance of the impact of phosphorylation in the proline-rich region of the disordered Tau protein. Proteins 2011; 80:454-62. [PMID: 22072628 DOI: 10.1002/prot.23210] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 09/22/2011] [Accepted: 09/23/2011] [Indexed: 11/10/2022]
Abstract
Phosphorylation of the neuronal Tau protein is implicated in both the regulation of its physiological function of microtubule stabilization and its pathological propensity to aggregate into the fibers that characterize Alzheimer's diseased neurons. However, how specific phosphorylation events influence both aspects of Tau biology remains largely unknown. In this study, we address the structural impact of phosphorylation of the Tau protein by Nuclear Magnetic Resonance (NMR) spectroscopy on a functional fragment of Tau (Tau[Ser208-Ser324] = TauF4). TauF4 was phosphorylated by the proline-directed CDK2/CycA3 kinase on Thr231 (generating the AT180 epitope), Ser235, and equally on Thr212 and Thr217 in the Proline-rich region (Tau[Ser208-Gln244] or PRR). These modifications strongly decrease the capacity of TauF4 to polymerize tubulin into microtubules. While all the NMR parameters are consistent with a globally disordered Tau protein fragment, local clusters of structuration can be defined. The most salient result of our NMR analysis is that phosphorylation in the PRR stabilizes a short α-helix that runs from pSer235 till the very beginning of the microtubule-binding region (Tau[Thr245-Ser324] or MTBR of TauF4). Phosphorylation of Thr231/Ser235 creates a N-cap with helix stabilizing role while phosphorylation of Thr212/Thr217 does not induce modification of the local transient secondary structure, showing that the stabilizing effect is sequence specific. Using paramagnetic relaxation experiments, we additionally show a transient interaction between the PRR and the MTBR, observed in both TauF4 and phospho-TauF4.
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Affiliation(s)
- Nathalie Sibille
- CNRS-UMR 8576 UGSF-IFR 147, Université des Sciences et Technologies de Lille 1, 59655 Villeneuve d'Ascq Cedex, France
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Kovacs D, Agoston B, Tompa P. Disordered plant LEA proteins as molecular chaperones. Plant Signal Behav 2008; 3:710-3. [PMID: 19704836 PMCID: PMC2634567 DOI: 10.4161/psb.3.9.6434] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Accepted: 06/13/2008] [Indexed: 05/08/2023]
Abstract
Plants often respond to abiotic stresses by the increased expression of LEA (late embryogenesis abundant) proteins, so called because they also accompany seed formation. Whereas the cellular function of LEA proteins in mitigating the damage caused by stress is clear, the molecular mechanisms of their action are rather enigmatic. Several models have been developed, based on their putative activities as ion sinks, stabilizers of membrane structure, buffers of hydrate water, antioxidants and/or chaperones. Due to their known structural flexibility, this latter idea has received little experimental attention thus far. Recently, however, it has been suggested that intrinsically disordered proteins (IDPs) may exert chaperone activity by an "entropy transfer" mechanism. In our subsequent study published in the May issue of Plant Physiology, we provided evidence that two group 2 LEA proteins, ERD (early response to dehydration) 10 and 14, are potent molecular chaperones. This observation may have far-reaching implications, as it may explain how LEA proteins of ill-defined structures protect plant cells during dehydration, and it may also lead to the general experimental validation of the entropy transfer model of disordered chaperones.
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Affiliation(s)
- Denes Kovacs
- Institute of Enzymology; Biological Research Center; Hungarian Academy of Sciences; Budapest, Hungary
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