1
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Vogl DP, Mateos B, Migotti M, Felkl M, Conibear AC, Konrat R, Becker CFW. Semisynthesis of segmentally isotope-labeled and site-specifically palmitoylated CD44 cytoplasmic tail. Bioorg Med Chem 2024; 100:117617. [PMID: 38306881 DOI: 10.1016/j.bmc.2024.117617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/19/2024] [Accepted: 01/26/2024] [Indexed: 02/04/2024]
Abstract
CD44, a ubiquitously expressed transmembrane receptor, plays a crucial role in cell growth, migration, and tumor progression. Dimerization of CD44 is a key event in signal transduction and has emerged as a potential target for anti-tumor therapies. Palmitoylation, a posttranslational modification, disrupts CD44 dimerization and promotes CD44 accumulation in ordered membrane domains. However, the effects of palmitoylation on the structure and dynamics of CD44 at atomic resolution remain poorly understood. Here, we present a semisynthetic approach combining solid-phase peptide synthesis, recombinant expression, and native chemical ligation to investigate the impact of palmitoylation on the cytoplasmic domain (residues 669-742) of CD44 (CD44ct) by NMR spectroscopy. A segmentally isotope-labeled and site-specifically palmitoylated CD44 variant enabled NMR studies, which revealed chemical shift perturbations and indicated local and long-range conformational changes induced by palmitoylation. The long-range effects suggest altered intramolecular interactions and potential modulation of membrane association patterns. Semisynthetic, palmitoylated CD44ct serves as the basis for studying CD44 clustering, conformational changes, and localization within lipid rafts, and could be used to investigate its role as a tumor suppressor and to explore its therapeutic potential.
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Affiliation(s)
- Dominik P Vogl
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Str. 38, 1090 Vienna, Austria; University of Vienna, Vienna Doctoral School in Chemistry (DoSChem), Währinger Str. 42, 1090 Vienna, Austria
| | - Borja Mateos
- Max Perutz Laboratories, Vienna Biocenter Campus 5, 1030 Vienna, Austria
| | - Mario Migotti
- Max Perutz Laboratories, Vienna Biocenter Campus 5, 1030 Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, A-1030 Vienna, Austria
| | - Manuel Felkl
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Str. 38, 1090 Vienna, Austria
| | - Anne C Conibear
- TU Wien, Institute of Applied Synthetic Chemistry, Getreidemarkt 9, 1060 Vienna, Austria
| | - Robert Konrat
- Max Perutz Laboratories, Vienna Biocenter Campus 5, 1030 Vienna, Austria
| | - Christian F W Becker
- University of Vienna, Vienna Doctoral School in Chemistry (DoSChem), Währinger Str. 42, 1090 Vienna, Austria.
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2
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Kokubu R, Ohno S, Manabe N, Yamaguchi Y. Molecular Dynamics Simulation and Docking of MUC1 O-Glycopeptide. Methods Mol Biol 2024; 2763:373-379. [PMID: 38347427 DOI: 10.1007/978-1-0716-3670-1_32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Advances in computer performance and computational simulations allow increasing sophistication in applications in biological systems. Molecular dynamics (MD) simulations are especially suitable for studying conformation, dynamics, and interaction of flexible biomolecules such as free glycans and glycopeptides. Computer simulations are best performed when the scope and limitations in performance have been thoroughly assessed. Proper outputs are obtained only under suitable parameter settings, and results need to be properly validated. In this chapter, we will introduce an example of molecular dynamics simulations of MUC1 O-glycopeptide and its docking to anti-MUC1 antibody Fv fragment.
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Affiliation(s)
- Ryoka Kokubu
- Division of Structural Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Shiho Ohno
- Division of Structural Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Noriyoshi Manabe
- Division of Structural Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Yoshiki Yamaguchi
- Division of Structural Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Japan.
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3
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Johnson HM, Ahmed CM. Disparate viral pandemics from COVID19 to monkeypox and beyond: a simple, effective and universal therapeutic approach hiding in plain sight. Front Immunol 2023; 14:1208828. [PMID: 38106428 PMCID: PMC10722180 DOI: 10.3389/fimmu.2023.1208828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 11/16/2023] [Indexed: 12/19/2023] Open
Abstract
The field of antiviral therapeutics is fixated on COVID19 and rightly so as the fatalities at the height of the pandemic in the United States were almost 1,000,000 in a twelve month period spanning parts of 2020/2021. A coronavirus called SARS-CoV2 is the causative virus. Development of a vaccine through molecular biology approaches with mRNA as the inducer of virus spike protein has played a major role in driving down mortality and morbidity. Antivirals have been of marginal value in established infections at the level of hospitalization. Thus, the current focus is on early symptomatic infection of about the first five days. The Pfizer drug paxlovid which is composed of nirmatrelvir, a peptidomimetic protease inhibitor of SARS-CoV2 Mpro enzyme, and ritonavir to retard degradation of nirmatrelvir, is the current FDA recommended treatment of early COVID19. There is no evidence of broad antiviral activity of paxlovid against other diverse viruses such as the influenza virus, poxviruses, as well as a host of respiratory viruses. Although type I interferons (IFNs) are effective against SARS-CoV2 in cell cultures and in early COVID19 infections, they have not been broadly recommended as therapeutics for COVID19. We have developed stable peptidomimetics of both types I and II IFNs based on our noncanonical model of IFN signaling involving the C-terminus of the IFNs. We have also identified two members of intracellular checkpoint inhibitors called suppressors of cytokine signaling (SOCS), SOCS1 and SOCS3 (SOCS1/3), and shown that they are virus induced intrinsic virulence proteins with activity against IFN signaling enzymes JAK2 and TYK2. We developed a peptidomimetic antagonist, based on JAK2 activation loop, against SOCS1/3 and showed that it synergizes with the IFN mimetics for potent broad spectrum antiviral activity without the toxicity of intact IFN molecules. IFN mimetics and the SOCS1/3 antagonist should have an advantage over currently used antivirals in terms of safety and potency against a broad spectrum of viruses.
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Affiliation(s)
- Howard M. Johnson
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL, United States
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4
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Sanganna Gari RR, Tagiltsev G, Pumroy RA, Jiang Y, Blackledge M, Moiseenkova-Bell VY, Scheuring S. Intrinsically disordered regions in TRPV2 mediate protein-protein interactions. Commun Biol 2023; 6:966. [PMID: 37736816 PMCID: PMC10516966 DOI: 10.1038/s42003-023-05343-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 09/11/2023] [Indexed: 09/23/2023] Open
Abstract
Transient receptor potential (TRP) ion channels are gated by diverse intra- and extracellular stimuli leading to cation inflow (Na+, Ca2+) regulating many cellular processes and initiating organismic somatosensation. Structures of most TRP channels have been solved. However, structural and sequence analysis showed that ~30% of the TRP channel sequences, mainly the N- and C-termini, are intrinsically disordered regions (IDRs). Unfortunately, very little is known about IDR 'structure', dynamics and function, though it has been shown that they are essential for native channel function. Here, we imaged TRPV2 channels in membranes using high-speed atomic force microscopy (HS-AFM). The dynamic single molecule imaging capability of HS-AFM allowed us to visualize IDRs and revealed that N-terminal IDRs were involved in intermolecular interactions. Our work provides evidence about the 'structure' of the TRPV2 IDRs, and that the IDRs may mediate protein-protein interactions.
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Affiliation(s)
| | - Grigory Tagiltsev
- Department of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Ruth A Pumroy
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yining Jiang
- Department of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
- Biochemistry & Structural Biology, Cell & Developmental Biology, and Molecular Biology (BCMB) Program, Weill Cornell Graduate School of Biomedical Sciences, New York, USA
| | - Martin Blackledge
- Université Grenoble Alpes, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Institut de Biologie Structurale (IBS), 38000, Grenoble, France
| | - Vera Y Moiseenkova-Bell
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Simon Scheuring
- Department of Anesthesiology, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
- Department of Physiology and Biophysics, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
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5
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Kragelj J, Dumarieh R, Xiao Y, Frederick KK. Conformational ensembles explain NMR spectra of frozen intrinsically disordered proteins. Protein Sci 2023; 32:e4628. [PMID: 36930141 PMCID: PMC10108432 DOI: 10.1002/pro.4628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/12/2023] [Accepted: 03/14/2023] [Indexed: 03/18/2023]
Abstract
Protein regions which are intrinsically disordered, exist as an ensemble of rapidly interconverting structures. Cooling proteins to cryogenic temperatures for dynamic nuclear polarization (DNP) magic angle spinning (MAS) NMR studies suspends most of the motions, resulting in peaks that are broad but not featureless. To demonstrate that detailed conformational restraints can be retrieved from the peak shapes of frozen proteins alone, we developed and used a simulation framework to assign peak features to conformers in the ensemble. We validated our simulations by comparing them to spectra of α-synuclein acquired under different experimental conditions. Our assignments of peaks to discrete dihedral angle populations suggest that structural constraints are attainable under cryogenic conditions. The ability to infer ensemble populations from peak shapes has important implications for DNP MAS NMR studies of proteins with regions of disorder in living cells because chemical shifts are the most accessible measured parameter.
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Affiliation(s)
- Jaka Kragelj
- Department of BiophysicsUT Southwestern Medical CenterDallasTexas75390‐8816USA
- Present address:
National Institute of ChemistryHajdrihova 191001LjubljanaSlovenia
| | - Rania Dumarieh
- Department of BiophysicsUT Southwestern Medical CenterDallasTexas75390‐8816USA
| | - Yiling Xiao
- Department of BiophysicsUT Southwestern Medical CenterDallasTexas75390‐8816USA
| | - Kendra K. Frederick
- Department of BiophysicsUT Southwestern Medical CenterDallasTexas75390‐8816USA
- Center for Alzheimer's and Neurodegenerative DiseaseUT Southwestern Medical CenterDallasTexas75390USA
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6
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Chowdhury UD, Paul A, Bhargava BL. Interaction of the tau fibrils with the neuronal membrane. Biophys Chem 2023; 298:107024. [PMID: 37104971 DOI: 10.1016/j.bpc.2023.107024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 04/17/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023]
Abstract
Tau proteins are recently gaining a lot of interest due to their active role in causing a range of tauopathies. Molecular mechanisms underlying the tau interaction with the neuronal membrane are hitherto unknown and difficult to characterize using experimental methods. Using the cryo-EM structure of the tau-fibrils we have used atomistic molecular dynamics simulation to model the tau fibril and neuronal membrane interaction using explicit solvation. The dynamics and structural characteristics of the tau fibril with the neuronal membrane are compared to the tau fibril in the aqueous phase to corroborate the effect of the neuronal membrane in the tau structure. Tau fibrils have been modelled using CHARMM-36m force field and the six component neuronal membrane composition is taken from the earlier simulation results. The timescale conceivable in our molecular dynamics simulations is of the order of microseconds which captures the onset of the interaction of the tau fibrils with the neuronal membrane. This interaction is found to impact the tau pathogenesis that finally causes neuronal toxicity. Our study initiates the understanding of tau conformational ensemble in the presence of neuronal membrane and sheds the light on the significant tau-membrane interactions.
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Affiliation(s)
- Unmesh D Chowdhury
- School of Chemical Sciences, National Institute of Science Education & Research-Bhubaneswar, An OCC of Homi Bhabha National Institute, P.O. Jatni, Khurda, Odisha 752050, India
| | - Arnav Paul
- School of Chemical Sciences, National Institute of Science Education & Research-Bhubaneswar, An OCC of Homi Bhabha National Institute, P.O. Jatni, Khurda, Odisha 752050, India
| | - B L Bhargava
- School of Chemical Sciences, National Institute of Science Education & Research-Bhubaneswar, An OCC of Homi Bhabha National Institute, P.O. Jatni, Khurda, Odisha 752050, India.
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7
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Wohl S, Zheng W. Interpreting Transient Interactions of Intrinsically Disordered Proteins. J Phys Chem B 2023; 127:2395-2406. [PMID: 36917561 PMCID: PMC10038935 DOI: 10.1021/acs.jpcb.3c00096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
The flexible nature of intrinsically disordered proteins (IDPs) gives rise to a conformational ensemble with a diverse set of conformations. The simplest way to describe this ensemble is through a homopolymer model without any specific interactions. However, there has been growing evidence that the conformational properties of IDPs and their relevant functions can be affected by transient interactions between specific and even nonlocal pairs of amino acids. Interpreting these interactions from experimental methods, each of which is most sensitive to a different distance regime referred to as probing length, remains a challenging and unsolved problem. Here, we first show that transient interactions can be realized between short fragments of charged amino acids by generating conformational ensembles using model disordered peptides and coarse-grained simulations. Using these ensembles, we investigate how sensitive different types of experimental measurements are to the presence of transient interactions. We find methods with shorter probing lengths to be more appropriate for detecting these transient interactions, but one experimental method is not sufficient due to the existence of other weak interactions typically seen in IDPs. Finally, we develop an adjusted polymer model with an additional short-distance peak which can robustly reproduce the distance distribution function from two experimental measurements with complementary short and long probing lengths. This new model can suggest whether a homopolymer model is insufficient for describing a specific IDP and meets the challenge of quantitatively identifying specific, transient interactions from a background of nonspecific, weak interactions.
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Affiliation(s)
- Samuel Wohl
- Department of Physics, Arizona State University, Tempe, Arizona 85287, United States
| | - Wenwei Zheng
- College of Integrative Sciences and Arts, Arizona State University, Mesa, Arizona 85212, United States
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8
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Structural Studies of Expressed tIK, Anti-Inflammatory Peptide. Int J Mol Sci 2022; 24:ijms24010636. [PMID: 36614076 PMCID: PMC9820745 DOI: 10.3390/ijms24010636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/12/2022] [Accepted: 12/27/2022] [Indexed: 12/31/2022] Open
Abstract
Cytokine imbalance is one of the causes of inflammation. Inflammation has yet to be adequately treated without side effects. Therefore, we tried to develop a peptide drug with minimal side effects. Peptide drugs have the advantage of being bio-friendly and bio-specific. In a previous study, three peptides with anti-inflammatory activity were derived based on a truncated IK (tIK) protein, which was a fragment of the IK protein with anti-inflammatory effects. The objective of this study was to optimize the process of expressing, isolating, and purifying the three peptides using bacterial strains and describe the process. Circular dichroism and solution state nuclear magnetic resonance spectroscopy were performed on the final purified high-purity peptide and its secondary structure was also identified.
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9
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Theillet FX, Luchinat E. In-cell NMR: Why and how? PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 132-133:1-112. [PMID: 36496255 DOI: 10.1016/j.pnmrs.2022.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 04/19/2022] [Accepted: 04/27/2022] [Indexed: 06/17/2023]
Abstract
NMR spectroscopy has been applied to cells and tissues analysis since its beginnings, as early as 1950. We have attempted to gather here in a didactic fashion the broad diversity of data and ideas that emerged from NMR investigations on living cells. Covering a large proportion of the periodic table, NMR spectroscopy permits scrutiny of a great variety of atomic nuclei in all living organisms non-invasively. It has thus provided quantitative information on cellular atoms and their chemical environment, dynamics, or interactions. We will show that NMR studies have generated valuable knowledge on a vast array of cellular molecules and events, from water, salts, metabolites, cell walls, proteins, nucleic acids, drugs and drug targets, to pH, redox equilibria and chemical reactions. The characterization of such a multitude of objects at the atomic scale has thus shaped our mental representation of cellular life at multiple levels, together with major techniques like mass-spectrometry or microscopies. NMR studies on cells has accompanied the developments of MRI and metabolomics, and various subfields have flourished, coined with appealing names: fluxomics, foodomics, MRI and MRS (i.e. imaging and localized spectroscopy of living tissues, respectively), whole-cell NMR, on-cell ligand-based NMR, systems NMR, cellular structural biology, in-cell NMR… All these have not grown separately, but rather by reinforcing each other like a braided trunk. Hence, we try here to provide an analytical account of a large ensemble of intricately linked approaches, whose integration has been and will be key to their success. We present extensive overviews, firstly on the various types of information provided by NMR in a cellular environment (the "why", oriented towards a broad readership), and secondly on the employed NMR techniques and setups (the "how", where we discuss the past, current and future methods). Each subsection is constructed as a historical anthology, showing how the intrinsic properties of NMR spectroscopy and its developments structured the accessible knowledge on cellular phenomena. Using this systematic approach, we sought i) to make this review accessible to the broadest audience and ii) to highlight some early techniques that may find renewed interest. Finally, we present a brief discussion on what may be potential and desirable developments in the context of integrative studies in biology.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
| | - Enrico Luchinat
- Dipartimento di Scienze e Tecnologie Agro-Alimentari, Alma Mater Studiorum - Università di Bologna, Piazza Goidanich 60, 47521 Cesena, Italy; CERM - Magnetic Resonance Center, and Neurofarba Department, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy
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10
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Chowdhury UD, Paul A, Bhargava BL. The effect of lipid composition on the dynamics of tau fibrils. Proteins 2022; 90:2103-2115. [DOI: 10.1002/prot.26401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/01/2022] [Accepted: 07/15/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Unmesh Dutta Chowdhury
- School of Chemical Sciences National Institute of Science Education & Research‐Bhubaneswar, OCC of Homi Bhabha National Institute Khurda Odisha India
| | - Arnav Paul
- School of Chemical Sciences National Institute of Science Education & Research‐Bhubaneswar, OCC of Homi Bhabha National Institute Khurda Odisha India
| | - B. L. Bhargava
- School of Chemical Sciences National Institute of Science Education & Research‐Bhubaneswar, OCC of Homi Bhabha National Institute Khurda Odisha India
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11
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Piersimoni L, Abd El Malek M, Bhatia T, Bender J, Brankatschk C, Calvo Sánchez J, Dayhoff GW, Di Ianni A, Figueroa Parra JO, Garcia-Martinez D, Hesselbarth J, Köppen J, Lauth LM, Lippik L, Machner L, Sachan S, Schmidt L, Selle R, Skalidis I, Sorokin O, Ubbiali D, Voigt B, Wedler A, Wei AAJ, Zorn P, Dunker AK, Köhn M, Sinz A, Uversky VN. Lighting up Nobel Prize-winning studies with protein intrinsic disorder. Cell Mol Life Sci 2022; 79:449. [PMID: 35882686 PMCID: PMC11072364 DOI: 10.1007/s00018-022-04468-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/18/2022] [Accepted: 07/04/2022] [Indexed: 11/03/2022]
Abstract
Intrinsically disordered proteins and regions (IDPs and IDRs) and their importance in biology are becoming increasingly recognized in biology, biochemistry, molecular biology and chemistry textbooks, as well as in current protein science and structural biology curricula. We argue that the sequence → dynamic conformational ensemble → function principle is of equal importance as the classical sequence → structure → function paradigm. To highlight this point, we describe the IDPs and/or IDRs behind the discoveries associated with 17 Nobel Prizes, 11 in Physiology or Medicine and 6 in Chemistry. The Nobel Laureates themselves did not always mention that the proteins underlying the phenomena investigated in their award-winning studies are in fact IDPs or contain IDRs. In several cases, IDP- or IDR-based molecular functions have been elucidated, while in other instances, it is recognized that the respective protein(s) contain IDRs, but the specific IDR-based molecular functions have yet to be determined. To highlight the importance of IDPs and IDRs as general principle in biology, we present here illustrative examples of IDPs/IDRs in Nobel Prize-winning mechanisms and processes.
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Affiliation(s)
- Lolita Piersimoni
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Marina Abd El Malek
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Twinkle Bhatia
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Julian Bender
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Christin Brankatschk
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Jaime Calvo Sánchez
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Guy W Dayhoff
- Department of Chemistry, College of Art and Sciences, University of South Florida, Tampa, FL, 33620, USA
| | - Alessio Di Ianni
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | | | - Dailen Garcia-Martinez
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Julia Hesselbarth
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Janett Köppen
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Luca M Lauth
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Laurin Lippik
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Lisa Machner
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Shubhra Sachan
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Lisa Schmidt
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Robin Selle
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Ioannis Skalidis
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Oleksandr Sorokin
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Daniele Ubbiali
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Bruno Voigt
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Alice Wedler
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Alan An Jung Wei
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Peter Zorn
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Alan Keith Dunker
- Department of Biochemistry and Molecular Biology, Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Marcel Köhn
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany.
| | - Andrea Sinz
- Research Training Group RTG2467, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany.
| | - Vladimir N Uversky
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA.
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12
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Gomes GNW, Namini A, Gradinaru CC. Integrative Conformational Ensembles of Sic1 Using Different Initial Pools and Optimization Methods. Front Mol Biosci 2022; 9:910956. [PMID: 35923464 PMCID: PMC9342850 DOI: 10.3389/fmolb.2022.910956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/21/2022] [Indexed: 01/02/2023] Open
Abstract
Intrinsically disordered proteins play key roles in regulatory protein interactions, but their detailed structural characterization remains challenging. Here we calculate and compare conformational ensembles for the disordered protein Sic1 from yeast, starting from initial ensembles that were generated either by statistical sampling of the conformational landscape, or by molecular dynamics simulations. Two popular, yet contrasting optimization methods were used, ENSEMBLE and Bayesian Maximum Entropy, to achieve agreement with experimental data from nuclear magnetic resonance, small-angle X-ray scattering and single-molecule Förster resonance energy transfer. The comparative analysis of the optimized ensembles, including secondary structure propensity, inter-residue contact maps, and the distributions of hydrogen bond and pi interactions, revealed the importance of the physics-based generation of initial ensembles. The analysis also provides insights into designing new experiments that report on the least restrained features among the optimized ensembles. Overall, differences between ensembles optimized from different priors were greater than when using the same prior with different optimization methods. Generating increasingly accurate, reliable and experimentally validated ensembles for disordered proteins is an important step towards a mechanistic understanding of their biological function and involvement in various diseases.
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Affiliation(s)
- Gregory-Neal W. Gomes
- Department of Physics, University of Toronto, Toronto, ON, Canada
- *Correspondence: Gregory-Neal W. Gomes, ; Claudiu C. Gradinaru,
| | - Ashley Namini
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Claudiu C. Gradinaru
- Department of Physics, University of Toronto, Toronto, ON, Canada
- Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
- *Correspondence: Gregory-Neal W. Gomes, ; Claudiu C. Gradinaru,
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13
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Clore GM. NMR spectroscopy, excited states and relevance to problems in cell biology - transient pre-nucleation tetramerization of huntingtin and insights into Huntington's disease. J Cell Sci 2022; 135:jcs258695. [PMID: 35703323 PMCID: PMC9270955 DOI: 10.1242/jcs.258695] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Solution nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for analyzing three-dimensional structure and dynamics of macromolecules at atomic resolution. Recent advances have exploited the unique properties of NMR in exchanging systems to detect, characterize and visualize excited sparsely populated states of biological macromolecules and their complexes, which are only transient. These states are invisible to conventional biophysical techniques, and play a key role in many processes, including molecular recognition, protein folding, enzyme catalysis, assembly and fibril formation. All the NMR techniques make use of exchange between sparsely populated NMR-invisible and highly populated NMR-visible states to transfer a magnetization property from the invisible state to the visible one where it can be easily detected and quantified. There are three classes of NMR experiments that rely on differences in distance, chemical shift or transverse relaxation (molecular mass) between the NMR-visible and -invisible species. Here, I illustrate the application of these methods to unravel the complex mechanism of sub-millisecond pre-nucleation oligomerization of the N-terminal region of huntingtin, encoded by exon-1 of the huntingtin gene, where CAG expansion leads to Huntington's disease, a fatal autosomal-dominant neurodegenerative condition. I also discuss how inhibition of tetramerization blocks the much slower (by many orders of magnitude) process of fibril formation.
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Affiliation(s)
- G. Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
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14
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Measuring thermodynamic preferences to form non-native conformations in nucleic acids using ultraviolet melting. Proc Natl Acad Sci U S A 2022; 119:e2112496119. [PMID: 35671421 PMCID: PMC9214542 DOI: 10.1073/pnas.2112496119] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Thermodynamic preferences to form non-native conformations are crucial for understanding how nucleic acids fold and function. However, they are difficult to measure experimentally because this requires accurately determining the population of minor low-abundance (<10%) conformations in a sea of other conformations. Here, we show that melting experiments enable facile measurements of thermodynamic preferences to adopt nonnative conformations in DNA and RNA. The key to this "delta-melt" approach is to use chemical modifications to render specific minor non-native conformations the major state. The validity and robustness of delta-melt is established for four different non-native conformations under various physiological conditions and sequence contexts through independent measurements of thermodynamic preferences using NMR. Delta-melt is faster relative to NMR, simple, and cost-effective and enables thermodynamic preferences to be measured for exceptionally low-populated conformations. Using delta-melt, we obtained rare insights into conformational cooperativity, obtaining evidence for significant cooperativity (1.0 to 2.5 kcal/mol) when simultaneously forming two adjacent Hoogsteen base pairs. We also measured the thermodynamic preferences to form G-C+ and A-T Hoogsteen and A-T base open states for nearly all 16 trinucleotide sequence contexts and found distinct sequence-specific variations on the order of 2 to 3 kcal/mol. This rich landscape of sequence-specific non-native minor conformations in the DNA double helix may help shape the sequence specificity of DNA biochemistry. Thus, melting experiments can now be used to access thermodynamic information regarding regions of the free energy landscape of biomolecules beyond the native folded and unfolded conformations.
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15
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Friedrich D, Marintchev A, Arthanari H. The metaphorical swiss army knife: The multitude and diverse roles of HEAT domains in eukaryotic translation initiation. Nucleic Acids Res 2022; 50:5424-5442. [PMID: 35552740 PMCID: PMC9177959 DOI: 10.1093/nar/gkac342] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/20/2022] [Accepted: 04/22/2022] [Indexed: 11/24/2022] Open
Abstract
Biomolecular associations forged by specific interaction among structural scaffolds are fundamental to the control and regulation of cell processes. One such structural architecture, characterized by HEAT repeats, is involved in a multitude of cellular processes, including intracellular transport, signaling, and protein synthesis. Here, we review the multitude and versatility of HEAT domains in the regulation of mRNA translation initiation. Structural and cellular biology approaches, as well as several biophysical studies, have revealed that a number of HEAT domain-mediated interactions with a host of protein factors and RNAs coordinate translation initiation. We describe the basic structural architecture of HEAT domains and briefly introduce examples of the cellular processes they dictate, including nuclear transport by importin and RNA degradation. We then focus on proteins in the translation initiation system featuring HEAT domains, specifically the HEAT domains of eIF4G, DAP5, eIF5, and eIF2Bϵ. Comparative analysis of their remarkably versatile interactions, including protein–protein and protein–RNA recognition, reveal the functional importance of flexible regions within these HEAT domains. Here we outline how HEAT domains orchestrate fundamental aspects of translation initiation and highlight open mechanistic questions in the area.
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Affiliation(s)
- Daniel Friedrich
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Assen Marintchev
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, MA, USA
| | - Haribabu Arthanari
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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16
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Cubuk J, Soranno A. Macromolecular crowding and intrinsically disordered proteins: a polymer physics perspective. CHEMSYSTEMSCHEM 2022. [DOI: 10.1002/syst.202100051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jasmine Cubuk
- Washington University in St Louis Biochemistry and Molecular Biophysics UNITED STATES
| | - Andrea Soranno
- Washington University in St Louis Biochemistry and Molecular Biophysics 660 St Euclid Ave 63110 St Louis UNITED STATES
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17
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Abstract
In-cell structural biology aims at extracting structural information about proteins or nucleic acids in their native, cellular environment. This emerging field holds great promise and is already providing new facts and outlooks of interest at both fundamental and applied levels. NMR spectroscopy has important contributions on this stage: It brings information on a broad variety of nuclei at the atomic scale, which ensures its great versatility and uniqueness. Here, we detail the methods, the fundamental knowledge, and the applications in biomedical engineering related to in-cell structural biology by NMR. We finally propose a brief overview of the main other techniques in the field (EPR, smFRET, cryo-ET, etc.) to draw some advisable developments for in-cell NMR. In the era of large-scale screenings and deep learning, both accurate and qualitative experimental evidence are as essential as ever to understand the interior life of cells. In-cell structural biology by NMR spectroscopy can generate such a knowledge, and it does so at the atomic scale. This review is meant to deliver comprehensive but accessible information, with advanced technical details and reflections on the methods, the nature of the results, and the future of the field.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
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18
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Kulkarni P, Leite VBP, Roy S, Bhattacharyya S, Mohanty A, Achuthan S, Singh D, Appadurai R, Rangarajan G, Weninger K, Orban J, Srivastava A, Jolly MK, Onuchic JN, Uversky VN, Salgia R. Intrinsically disordered proteins: Ensembles at the limits of Anfinsen's dogma. BIOPHYSICS REVIEWS 2022; 3:011306. [PMID: 38505224 PMCID: PMC10903413 DOI: 10.1063/5.0080512] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/17/2022] [Indexed: 03/21/2024]
Abstract
Intrinsically disordered proteins (IDPs) are proteins that lack rigid 3D structure. Hence, they are often misconceived to present a challenge to Anfinsen's dogma. However, IDPs exist as ensembles that sample a quasi-continuum of rapidly interconverting conformations and, as such, may represent proteins at the extreme limit of the Anfinsen postulate. IDPs play important biological roles and are key components of the cellular protein interaction network (PIN). Many IDPs can interconvert between disordered and ordered states as they bind to appropriate partners. Conformational dynamics of IDPs contribute to conformational noise in the cell. Thus, the dysregulation of IDPs contributes to increased noise and "promiscuous" interactions. This leads to PIN rewiring to output an appropriate response underscoring the critical role of IDPs in cellular decision making. Nonetheless, IDPs are not easily tractable experimentally. Furthermore, in the absence of a reference conformation, discerning the energy landscape representation of the weakly funneled IDPs in terms of reaction coordinates is challenging. To understand conformational dynamics in real time and decipher how IDPs recognize multiple binding partners with high specificity, several sophisticated knowledge-based and physics-based in silico sampling techniques have been developed. Here, using specific examples, we highlight recent advances in energy landscape visualization and molecular dynamics simulations to discern conformational dynamics and discuss how the conformational preferences of IDPs modulate their function, especially in phenotypic switching. Finally, we discuss recent progress in identifying small molecules targeting IDPs underscoring the potential therapeutic value of IDPs. Understanding structure and function of IDPs can not only provide new insight on cellular decision making but may also help to refine and extend Anfinsen's structure/function paradigm.
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Affiliation(s)
- Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California 91010, USA
| | - Vitor B. P. Leite
- Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP), São José do Rio Preto, São Paulo 15054-000, Brazil
| | - Susmita Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741246, India
| | - Supriyo Bhattacharyya
- Translational Bioinformatics, Center for Informatics, Department of Computational and Quantitative Medicine, City of Hope National Medical Center, Duarte, California 91010, USA
| | - Atish Mohanty
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California 91010, USA
| | - Srisairam Achuthan
- Center for Informatics, Division of Research Informatics, City of Hope National Medical Center, Duarte, California 91010, USA
| | - Divyoj Singh
- Center for BioSystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Rajeswari Appadurai
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Govindan Rangarajan
- Department of Mathematics, Indian Institute of Science, Bangalore 560012, India
| | - Keith Weninger
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| | | | - Anand Srivastava
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Mohit Kumar Jolly
- Center for BioSystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Jose N. Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005-1892, USA
| | | | - Ravi Salgia
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California 91010, USA
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19
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Tugarinov V, Ceccon A, Clore GM. NMR methods for exploring 'dark' states in ligand binding and protein-protein interactions. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 128:1-24. [PMID: 35282867 PMCID: PMC8921508 DOI: 10.1016/j.pnmrs.2021.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 05/24/2023]
Abstract
A survey, primarily based on work in the authors' laboratory during the last 10 years, is provided of recent developments in NMR studies of exchange processes involving protein-ligand and protein-protein interactions. We start with a brief overview of the theoretical background of Dark state Exchange Saturation Transfer (DEST) and lifetime line-broadening (ΔR2) NMR methodology. Some limitations of the DEST/ΔR2 methodology in applications to molecular systems with intermediate molecular weights are discussed, along with the means of overcoming these limitations with the help of closely related exchange NMR techniques, such as the measurements of Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion, exchange-induced chemical shifts or rapidly-relaxing components of relaxation decays. Some theoretical underpinnings of the quantitative description of global dynamics of proteins on the surface of very high molecular weight particles (nanoparticles) are discussed. Subsequently, several applications of DEST/ΔR2 methodology are described from a methodological perspective with an emphasis on providing examples of how kinetic and relaxation parameters for exchanging systems can be reliably extracted from NMR data for each particular model of exchange. Among exchanging systems that are not associated with high molecular weight species, we describe several exchange NMR-based studies that focus on kinetic modelling of transient pre-nucleation oligomerization of huntingtin peptides that precedes aggregation and fibril formation.
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Affiliation(s)
- Vitali Tugarinov
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, United States.
| | - Alberto Ceccon
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, United States
| | - G Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, United States.
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20
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Kodera N, Ando T. Visualization of intrinsically disordered proteins by high-speed atomic force microscopy. Curr Opin Struct Biol 2022; 72:260-266. [PMID: 34998124 DOI: 10.1016/j.sbi.2021.11.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/20/2021] [Accepted: 11/23/2021] [Indexed: 12/30/2022]
Abstract
High-speed atomic force microscopy (HS-AFM) is a powerful tool established 13 years ago. This methodology can capture individual protein molecules carrying out functional activities under near-physiological conditions, without chemical labeling, at 2-3 nm lateral and ∼0.1 nm vertical spatial resolution, and at sub-100 ms temporal resolution. Although most biological HS-AFM studies thus far target structured proteins, HS-AFM is also ideally suited to study the dynamics of intrinsically disordered proteins. Here we review some of the dynamic structures and processes of intrinsically disordered proteins that have been unveiled by HS-AFM imaging.
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Affiliation(s)
- Noriyuki Kodera
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Toshio Ando
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
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21
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Berry DBG, Clegg I, Codina A, Lyall CL, Lowe JP, Hintermair U. Convenient and accurate insight into solution-phase equilibria from FlowNMR titrations. REACT CHEM ENG 2022. [DOI: 10.1039/d2re00123c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Solution phase titrations are made easy by multi-nuclear FlowNMR spectroscopy with automated, continuous titre addition to give accurate insights into Brønsted acid/base, hydrogen bonding, Lewis acid/base and metal/ligand binding equilibria under native conditions.
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Affiliation(s)
- Daniel B. G. Berry
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - Ian Clegg
- Bruker UK Ltd, Banner Lane, CV4 9GH Coventry, UK
| | - Anna Codina
- Bruker UK Ltd, Banner Lane, CV4 9GH Coventry, UK
| | - Catherine L. Lyall
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - John P. Lowe
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
| | - Ulrich Hintermair
- Department of Chemistry, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Dynamic Reaction Monitoring Facility, University of Bath, Claverton Down, BA2 7AY Bath, UK
- Centre for Sustainable and Circular Technologies, University of Bath, Claverton Down, BA2 7AY Bath, UK
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22
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Saikia N, Yanez-Orozco IS, Qiu R, Hao P, Milikisiyants S, Ou E, Hamilton GL, Weninger KR, Smirnova TI, Sanabria H, Ding F. Integrative structural dynamics probing of the conformational heterogeneity in synaptosomal-associated protein 25. CELL REPORTS. PHYSICAL SCIENCE 2021; 2:100616. [PMID: 34888535 PMCID: PMC8654206 DOI: 10.1016/j.xcrp.2021.100616] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
SNAP-25 (synaptosomal-associated protein of 25 kDa) is a prototypical intrinsically disordered protein (IDP) that is unstructured by itself but forms coiled-coil helices in the SNARE complex. With high conformational heterogeneity, detailed structural dynamics of unbound SNAP-25 remain elusive. Here, we report an integrative method to probe the structural dynamics of SNAP-25 by combining replica-exchange discrete molecular dynamics (rxDMD) simulations and label-based experiments at ensemble and single-molecule levels. The rxDMD simulations systematically characterize the coil-to-molten globular transition and reconstruct structural ensemble consistent with prior ensemble experiments. Label-based experiments using Förster resonance energy transfer and double electron-electron resonance further probe the conformational dynamics of SNAP-25. Agreements between simulations and experiments under both ensemble and single-molecule conditions allow us to assign specific helix-coil transitions in SNAP-25 that occur in submillisecond timescales and potentially play a vital role in forming the SNARE complex. We expect that this integrative approach may help further our understanding of IDPs.
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Affiliation(s)
- Nabanita Saikia
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
- Department of Chemistry, Navajo Technical University, Chinle, AZ 86503, USA
| | | | - Ruoyi Qiu
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Pengyu Hao
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Erkang Ou
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - George L. Hamilton
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Keith R. Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Tatyana I. Smirnova
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Hugo Sanabria
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
- Lead contact
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23
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Morgan GJ. Transient disorder along pathways to amyloid. Biophys Chem 2021; 281:106711. [PMID: 34839162 DOI: 10.1016/j.bpc.2021.106711] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/27/2021] [Accepted: 10/28/2021] [Indexed: 01/15/2023]
Abstract
High-resolution structures of amyloid fibrils formed from normally-folded proteins have revealed non-native conformations of the polypeptide chains. Attaining these conformations apparently requires transition from the native state via a highly disordered conformation, in contrast to earlier models that posited a role for assembly of partially folded proteins. Modifications or interactions that extend the lifetime or constrain the conformations of these disordered states could act to enhance or suppress amyloid formation. Understanding how the properties of both the folded and transiently disordered structural ensembles influence the process of amyloid formation is a substantial challenge, but research into the properties of intrinsically disordered proteins will deliver important insights.
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Affiliation(s)
- Gareth J Morgan
- The Amyloidosis Center and Section of Hematology and Medical Oncology, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
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24
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Pajkos M, Dosztányi Z. Functions of intrinsically disordered proteins through evolutionary lenses. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 183:45-74. [PMID: 34656334 DOI: 10.1016/bs.pmbts.2021.06.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein sequences are the result of an evolutionary process that involves the balancing act of experimenting with novel mutations and selecting out those that have an undesirable functional outcome. In the case of globular proteins, the function relies on a well-defined conformation, therefore, there is a strong evolutionary pressure to preserve the structure. However, different evolutionary rules might apply for the group of intrinsically disordered regions and proteins (IDR/IDPs) that exist as an ensemble of fluctuating conformations. The function of IDRs can directly originate from their disordered state or arise through different types of molecular recognition processes. There is an amazing variety of ways IDRs can carry out their functions, and this is also reflected in their evolutionary properties. In this chapter we give an overview of the different types of evolutionary behavior of disordered proteins and associated functions in normal and disease settings.
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Affiliation(s)
- Mátyás Pajkos
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Zsuzsanna Dosztányi
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary.
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25
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Vogl DP, Conibear AC, Becker CFW. Segmental and site-specific isotope labelling strategies for structural analysis of posttranslationally modified proteins. RSC Chem Biol 2021; 2:1441-1461. [PMID: 34704048 PMCID: PMC8496066 DOI: 10.1039/d1cb00045d] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 08/11/2021] [Indexed: 01/02/2023] Open
Abstract
Posttranslational modifications can alter protein structures, functions and locations, and are important cellular regulatory and signalling mechanisms. Spectroscopic techniques such as nuclear magnetic resonance, infrared and Raman spectroscopy, as well as small-angle scattering, can provide insights into the structural and dynamic effects of protein posttranslational modifications and their impact on interactions with binding partners. However, heterogeneity of modified proteins from natural sources and spectral complexity often hinder analyses, especially for large proteins and macromolecular assemblies. Selective labelling of proteins with stable isotopes can greatly simplify spectra, as one can focus on labelled residues or segments of interest. Employing chemical biology tools for modifying and isotopically labelling proteins with atomic precision provides access to unique protein samples for structural biology and spectroscopy. Here, we review site-specific and segmental isotope labelling methods that are employed in combination with chemical and enzymatic tools to access posttranslationally modified proteins. We discuss illustrative examples in which these methods have been used to facilitate spectroscopic studies of posttranslationally modified proteins, providing new insights into biology.
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Affiliation(s)
- Dominik P Vogl
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry Währinger Straße 38 1090 Vienna Austria +43-1-4277-870510 +43-1-4277-70510
| | - Anne C Conibear
- The University of Queensland, School of Biomedical Sciences St Lucia Brisbane 4072 QLD Australia
| | - Christian F W Becker
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry Währinger Straße 38 1090 Vienna Austria +43-1-4277-870510 +43-1-4277-70510
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26
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Dyson HJ, Wright PE. NMR illuminates intrinsic disorder. Curr Opin Struct Biol 2021; 70:44-52. [PMID: 33951592 DOI: 10.1016/j.sbi.2021.03.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 03/30/2021] [Indexed: 02/06/2023]
Abstract
Nuclear magnetic resonance (NMR) has long been instrumental in the characterization of intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs). This method continues to offer rich insights into the nature of IDPs in solution, especially in combination with other biophysical methods such as small-angle scattering, single-molecule fluorescence, electron paramagnetic resonance (EPR), and mass spectrometry. Substantial advances have been made in recent years in studies of proteins containing both ordered and disordered domains and in the characterization of problematic sequences containing repeated tracts of a single or a few amino acids. These sequences are relevant to disease states such as Alzheimer's, Parkinson's, and Huntington's diseases, where disordered proteins misfold into harmful amyloid. Innovative applications of NMR are providing novel insights into mechanisms of protein aggregation and the complexity of IDP interactions with their targets. As a basis for understanding the solution structural ensembles, dynamic behavior, and functional mechanisms of IDPs and IDRs, NMR continues to prove invaluable.
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Affiliation(s)
- H Jane Dyson
- Department of Integrative Structural and Computational Biology and Skaggs Institute of Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, 92037, California, USA
| | - Peter E Wright
- Department of Integrative Structural and Computational Biology and Skaggs Institute of Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, 92037, California, USA.
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27
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Kozak F, Kurzbach D. How to assess the structural dynamics of transcription factors by integrating sparse NMR and EPR constraints with molecular dynamics simulations. Comput Struct Biotechnol J 2021; 19:2097-2105. [PMID: 33995905 PMCID: PMC8085671 DOI: 10.1016/j.csbj.2021.04.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/07/2021] [Accepted: 04/07/2021] [Indexed: 12/12/2022] Open
Abstract
We review recent advances in modeling structural ensembles of transcription factors from nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopic data, integrated with molecular dynamics (MD) simulations. We focus on approaches that confirm computed conformational ensembles by sparse constraints obtained from magnetic resonance. This combination enables the deduction of functional and structural protein models even if nuclear Overhauser effects (NOEs) are too scarce for conventional structure determination. We highlight recent insights into the folding-upon-DNA binding transitions of intrinsically disordered transcription factors that could be assessed using such integrative approaches.
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Affiliation(s)
- Fanny Kozak
- University Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Waehringer Str. 38, 1090 Vienna, Austria
| | - Dennis Kurzbach
- University Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Waehringer Str. 38, 1090 Vienna, Austria
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28
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Chen YW, Rahman SK. Fatal Attraction: The Case of Toxic Soluble Dimers of Truncated PQBP-1 Mutants in X-Linked Intellectual Disability. Int J Mol Sci 2021; 22:ijms22052240. [PMID: 33668121 PMCID: PMC7956452 DOI: 10.3390/ijms22052240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/20/2021] [Accepted: 02/20/2021] [Indexed: 11/16/2022] Open
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 the conformational disease proteins. The PQBP-1 mutants are unique in behaving as stable soluble dimers, which do not further develop into higher oligomers or aggregates. The toxicity of the PQBP-1 mutant dimers lies in the native functions (in transcription regulation and possibly, RNA splicing) being compromised, rather than proceeding to aggregation. Other examples of stable IDP dimers were discussed and we speculated on the roles of IDP dimerisation in protein evolution.
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Affiliation(s)
- Yu Wai Chen
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hunghom 999077, Hong Kong
- State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hunghom 999077, Hong Kong
- Correspondence:
| | - Shah Kamranur Rahman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK;
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Shrestha UR, Smith JC, Petridis L. Full structural ensembles of intrinsically disordered proteins from unbiased molecular dynamics simulations. Commun Biol 2021; 4:243. [PMID: 33623120 PMCID: PMC7902620 DOI: 10.1038/s42003-021-01759-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 01/07/2021] [Indexed: 12/13/2022] Open
Abstract
Molecular dynamics (MD) simulation is widely used to complement ensemble-averaged experiments of intrinsically disordered proteins (IDPs). However, MD often suffers from limitations of inaccuracy. Here, we show that enhancing the sampling using Hamiltonian replica-exchange MD (HREMD) led to unbiased and accurate ensembles, reproducing small-angle scattering and NMR chemical shift experiments, for three IDPs of varying sequence properties using two recently optimized force fields, indicating the general applicability of HREMD for IDPs. We further demonstrate that, unlike HREMD, standard MD can reproduce experimental NMR chemical shifts, but not small-angle scattering data, suggesting chemical shifts are insufficient for testing the validity of IDP ensembles. Surprisingly, we reveal that despite differences in their sequence, the inter-chain statistics of all three IDPs are similar for short contour lengths (< 10 residues). The results suggest that the major hurdle of generating an accurate unbiased ensemble for IDPs has now been largely overcome.
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Affiliation(s)
- Utsab R Shrestha
- Oak Ridge National Laboratory, Biosciences Division, UT/ORNL Center for Molecular Biophysics, Oak Ridge, TN, USA
| | - Jeremy C Smith
- Oak Ridge National Laboratory, Biosciences Division, UT/ORNL Center for Molecular Biophysics, Oak Ridge, TN, USA
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
| | - Loukas Petridis
- Oak Ridge National Laboratory, Biosciences Division, UT/ORNL Center for Molecular Biophysics, Oak Ridge, TN, USA.
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA.
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30
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Li ZL, Buck M. Beyond history and "on a roll": The list of the most well-studied human protein structures and overall trends in the protein data bank. Protein Sci 2021; 30:745-760. [PMID: 33550681 DOI: 10.1002/pro.4038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/02/2021] [Accepted: 02/05/2021] [Indexed: 12/17/2022]
Abstract
Of the roughly 20,000 canonical human protein sequences, as of January 20, 2021, 7,077 proteins have had their full or partial, medium- to high-resolution structures determined by x-ray crystallography or other methods. Which of these proteins dominate the protein data bank (the PDB) and why? In this paper, we list the 273 top human protein structures based on the number of their PDB entries. This set of proteins accounts for more than 40% of all available human PDB entries and represent past trends as well as current status for protein structural biology. We briefly discuss the relationship which some of the prominent protein structures have with protein research as a whole and mention their relevance to human diseases. The top-10 soluble and membrane proteins are all well-known (most of their first structures being deposited more than 30 years ago). Overall, there is no dramatic change in recent trends in the PDB. Remarkably, the number of structure depositions has grown nearly exponentially over the last 10 or more years (with a doubling time of 7 years for proteins, obtained from any organism). Growth in human protein structures is slightly faster (at 5.9 years). The information in this paper may be informative to senior scientists but also inspire researchers who are new to protein science, providing the year 2021 snap-shot for the state of protein structural biology.
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Affiliation(s)
- Zhen-Lu Li
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, Cleveland, Ohio, USA
| | - Matthias Buck
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, Cleveland, Ohio, USA.,Department of Pharmacology; Department of Neurosciences and Case Comprehensive Cancer Center, Case Western Reserve University, School of Medicine, Cleveland, Ohio, USA
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Medina E, R Latham D, Sanabria H. Unraveling protein's structural dynamics: from configurational dynamics to ensemble switching guides functional mesoscale assemblies. Curr Opin Struct Biol 2021; 66:129-138. [PMID: 33246199 PMCID: PMC7965259 DOI: 10.1016/j.sbi.2020.10.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/16/2020] [Accepted: 10/19/2020] [Indexed: 12/18/2022]
Abstract
Evidence regarding protein structure and function manifest the imperative role that dynamics play in proteins, underlining reconsideration of the unanimated sequence-to-structure-to-function paradigm. Structural dynamics portray a heterogeneous energy landscape described by conformational ensembles where each structural representation can be responsible for unique functions or enable macromolecular assemblies. Using the human p27/Cdk2/Cyclin A ternary complex as an example, we highlight the vital role of intramolecular and intermolecular dynamics for target recognition, binding, and inhibition as a critical modulator of cell division. Rapidly sampling configurations is critical for the population of different conformational ensembles encoding functional roles. To garner this knowledge, we present how the integration of (sub)ensemble and single-molecule fluorescence spectroscopy with molecular dynamic simulations can characterize structural dynamics linking the heterogeneous ensembles to function. The incorporation of dynamics into the sequence-to-structure-to-function paradigm promises to assist in tackling various challenges, including understanding the formation and regulation of mesoscale assemblies inside cells.
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Affiliation(s)
- Exequiel Medina
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile; Department of Physics and Astronomy, Clemson University, Clemson 29634, United States
| | - Danielle R Latham
- Department of Physics and Astronomy, Clemson University, Clemson 29634, United States
| | - Hugo Sanabria
- Department of Physics and Astronomy, Clemson University, Clemson 29634, United States.
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Alderson TR, Kay LE. NMR spectroscopy captures the essential role of dynamics in regulating biomolecular function. Cell 2021; 184:577-595. [PMID: 33545034 DOI: 10.1016/j.cell.2020.12.034] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/09/2020] [Accepted: 12/21/2020] [Indexed: 01/02/2023]
Abstract
Biomolecules are in constant motion. To understand how they function, and why malfunctions can cause disease, it is necessary to describe their three-dimensional structures in terms of dynamic conformational ensembles. Here, we demonstrate how nuclear magnetic resonance (NMR) spectroscopy provides an essential, dynamic view of structural biology that captures biomolecular motions at atomic resolution. We focus on examples that emphasize the diversity of biomolecules and biochemical applications that are amenable to NMR, such as elucidating functional dynamics in large molecular machines, characterizing transient conformations implicated in the onset of disease, and obtaining atomic-level descriptions of intrinsically disordered regions that make weak interactions involved in liquid-liquid phase separation. Finally, we discuss the pivotal role that NMR has played in driving forward our understanding of the biomolecular dynamics-function paradigm.
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Affiliation(s)
- T Reid Alderson
- Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Molecular Genetics, The University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Chemistry, The University of Toronto, Toronto, ON M5S A18, Canada.
| | - Lewis E Kay
- Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Molecular Genetics, The University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Chemistry, The University of Toronto, Toronto, ON M5S A18, Canada; Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
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Fatafta H, Samantray S, Sayyed-Ahmad A, Coskuner-Weber O, Strodel B. Molecular simulations of IDPs: From ensemble generation to IDP interactions leading to disorder-to-order transitions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 183:135-185. [PMID: 34656328 DOI: 10.1016/bs.pmbts.2021.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
Intrinsically disordered proteins (IDPs) lack a well-defined three-dimensional structure but do exhibit some dynamical and structural ordering. The structural plasticity of IDPs indicates that entropy-driven motions are crucial for their function. Many IDPs undergo function-related disorder-to-order transitions upon by their interaction with specific binding partners. Approaches that are based on both experimental and theoretical tools enable the biophysical characterization of IDPs. Molecular simulations provide insights into IDP structural ensembles and disorder-to-order transition mechanisms. However, such studies depend strongly on the chosen force field parameters and simulation techniques. In this chapter, we provide an overview of IDP characteristics, review all-atom force fields recently developed for IDPs, and present molecular dynamics-based simulation methods that allow IDP ensemble generation as well as the characterization of disorder-to-order transitions. In particular, we introduce metadynamics, replica exchange molecular dynamics simulations, and also kinetic models resulting from Markov State modeling, and provide various examples for the successful application of these simulation methods to IDPs.
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Affiliation(s)
- Hebah Fatafta
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
| | - Suman Samantray
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany; AICES Graduate School, RWTH Aachen University, Aachen, Germany
| | | | - Orkid Coskuner-Weber
- Molecular Biotechnology, Turkish-German University, Sahinkaya Caddesi, Istanbul, Turkey
| | - Birgit Strodel
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany; Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
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Musashi-1: An Example of How Polyalanine Tracts Contribute to Self-Association in the Intrinsically Disordered Regions of RNA-Binding Proteins. Int J Mol Sci 2020; 21:ijms21072289. [PMID: 32225071 PMCID: PMC7177541 DOI: 10.3390/ijms21072289] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/20/2020] [Accepted: 03/24/2020] [Indexed: 12/19/2022] Open
Abstract
RNA-binding proteins (RBPs) have intrinsically disordered regions (IDRs) whose biophysical properties have yet to be explored to the same extent as those of the folded RNA interacting domains. These IDRs are essential to the formation of biomolecular condensates, such as stress and RNA granules, but dysregulated assembly can be pathological. Because of their structural heterogeneity, IDRs are best studied by NMR spectroscopy. In this study, we used NMR spectroscopy to investigate the structural propensity and self-association of the IDR of the RBP Musashi-1. We identified two transient α-helical regions (residues ~208–218 and ~270–284 in the IDR, the latter with a polyalanine tract). Strong NMR line broadening in these regions and circular dichroism and micrography data suggest that the two α-helical elements and the hydrophobic residues in between may contribute to the formation of oligomers found in stress granules and implicated in Alzheimer’s disease. Bioinformatics analysis suggests that polyalanine stretches in the IDRs of RBPs may have evolved to promote RBP assembly.
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The Intrinsically Disordered Region of ExbD Is Required for Signal Transduction. J Bacteriol 2020; 202:JB.00687-19. [PMID: 31932309 DOI: 10.1128/jb.00687-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 01/03/2020] [Indexed: 12/26/2022] Open
Abstract
The TonB system actively transports vital nutrients across the unenergized outer membranes of the majority of Gram-negative bacteria. In this system, integral membrane proteins ExbB, ExbD, and TonB work together to transduce the proton motive force (PMF) of the inner membrane to customized active transporters in the outer membrane by direct and cyclic binding of TonB to the transporters. A PMF-dependent TonB-ExbD interaction is prevented by 10-residue deletions within a periplasmic disordered domain of ExbD adjacent to the cytoplasmic membrane. Here, we explored the function of the ExbD disordered domain in more detail. In vivo photo-cross-linking through sequential pBpa substitutions in the ExbD disordered domain captured five different ExbD complexes, some of which had been previously detected using in vivo formaldehyde cross-linking, a technique that lacks the residue-specific information that can be achieved through photo-cross-linking: two ExbB-ExbD heterodimers (one of which had not been detected previously), previously detected ExbD homodimers, previously detected PMF-dependent ExbD-TonB heterodimers, and for the first time, a predicted, ExbD-TonB PMF-independent interaction. The fact that multiple complexes were captured by the same pBpa substitution indicated the dynamic nature of ExbD interactions as the energy transduction cycle proceeded in vivo In this study, we also discovered that a conserved motif-V45, V47, L49, and P50-within the disordered domain was required for signal transduction to TonB and to the C-terminal domain of ExbD and was the source of motif essentiality.IMPORTANCE The TonB system is a virulence factor for Gram-negative pathogens. The mechanism by which cytoplasmic membrane proteins of the TonB system transduce an electrochemical gradient into mechanical energy is a long-standing mystery. TonB, ExbB, and ExbD primary amino acid sequences are characterized by regions of predicted intrinsic disorder, consistent with a proposed multiplicity of protein-protein contacts as TonB proceeds through an energy transduction cycle, a complex process that has yet to be recapitulated in vitro This study validates a region of intrinsic disorder near the ExbD transmembrane domain and identifies an essential conserved motif embedded within it that transduces signals to distal regions of ExbD suggested to configure TonB for productive interaction with outer membrane transporters.
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