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Andrews B, Schweitzer-Stenner R, Urbanc B. Intrinsic Conformational Dynamics of Glycine and Alanine in Polarizable Molecular Dynamics Force Fields: Comparison to Spectroscopic Data. J Phys Chem B 2024; 128:6217-6231. [PMID: 38877893 PMCID: PMC11215781 DOI: 10.1021/acs.jpcb.4c02278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/29/2024] [Accepted: 05/30/2024] [Indexed: 06/28/2024]
Abstract
Molecular dynamics (MD) is a great tool for elucidating conformational dynamics of proteins and peptides in water at the atomistic level that often surpasses the level of detail available experimentally. Structure predictions, however, are limited by the accuracy of the underlying MD force field. This limitation is particularly stark in the case of intrinsically disordered peptides and proteins, which are characterized by solvent-accessible and disordered peptide regions and domains. Recent studies show that most additive MD force fields, including CHARMM36m, do not reproduce the intrinsic conformational distributions of guest amino acid residues x in cationic GxG peptides in water in line with experimental data. Positing that a lack of polarizability in additive MD force fields may be the culprit for the reported discrepancies, we here examine the conformational dynamics of guest glycine and alanine residues in cationic GxG peptides in water using two polarizable MD force fields, CHARMM Drude and AMOEBA. Our results indicate that while AMOEBA captures the experimental data better than CHARMM Drude, neither of the two polarizable force fields offers an improvement of the Ramachandran distributions of glycine and alanine residues in cationic GGG and GAG peptides, respectively, over CHARMM36m.
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Affiliation(s)
- Brian Andrews
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | | | - Brigita Urbanc
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
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2
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Tolstova AP, Makarov AA, Adzhubei AA. Structure Comparison of Beta Amyloid Peptide Aβ 1-42 Isoforms. Molecular Dynamics Modeling. J Chem Inf Model 2024; 64:918-932. [PMID: 38241093 DOI: 10.1021/acs.jcim.3c01624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2024]
Abstract
Beta amyloid peptide Aβ 1-42 (Aβ42) has a unique dual role in the human organism, as both the peptide with an important physiological function and one of the most toxic biological compounds provoking Alzheimer's disease (AD). There are several known Aβ42 isoforms that we discuss here that are highly neurotoxic and lead to the early onset of AD. Aβ42 is an intrinsically disordered protein with no experimentally solved structure under physiological conditions. The objective of this research was to establish the appropriate molecular dynamics (MD) methodology and model a uniform set of structures for the Aβ42 isoforms that form the core of this study. For that purpose, force field selection and verification including convergence testing for MD simulations was made. Replica exchange MD and conventional MD modeling of several Aβ42 and Aβ16 isoforms that have neurotoxic and amyloidogenic effects impacting the severity of Alzheimer's disease were carried out with the optimal force field and solvent parameters. A standardized ensemble of structures for the Aβ42 and Aβ16 isoforms covering 30-50% of the conformational ensembles extracted from the free energy minima was calculated from MD trajectories. The resulting data set of modeled structures includes Aβ42 wild type, isoD7, pS8, D7H, and H6R-Aβ42 and Aβ16 wild type, isoD7, pS8, D7H, and H6R-Aβ16. The representative structures are given in the Supporting Information; they are open for public access. In the study, we also evaluated the differences between the structures of Aβ42 isoforms and speculate on their possible relevance to the known functions. Utilizing several representative structures for a single disordered protein for docking, with their subsequent averaging by conformations, would markedly increase the reliability of docking results.
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Affiliation(s)
- Anna P Tolstova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Alexander A Makarov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Alexei A Adzhubei
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
- Washington University School of Medicine and Health Sciences, Washington 20052, D.C., United States
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3
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Shahrajabian MH, Sun W. Characterization of Intrinsically Disordered Proteins in Healthy and Diseased States by Nuclear Magnetic Resonance. Rev Recent Clin Trials 2024; 19:176-188. [PMID: 38409704 DOI: 10.2174/0115748871271420240213064251] [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: 09/13/2023] [Revised: 11/10/2023] [Accepted: 12/13/2023] [Indexed: 02/28/2024]
Abstract
INTRODUCTION Intrinsically Disordered Proteins (IDPs) are active in different cellular procedures like ordered assembly of chromatin and ribosomes, interaction with membrane, protein, and ligand binding, molecular recognition, binding, and transportation via nuclear pores, microfilaments and microtubules process and disassembly, protein functions, RNA chaperone, and nucleic acid binding, modulation of the central dogma, cell cycle, and other cellular activities, post-translational qualification and substitute splicing, and flexible entropic linker and management of signaling pathways. METHODS The intrinsic disorder is a precise structural characteristic that permits IDPs/IDPRs to be involved in both one-to-many and many-to-one signaling. IDPs/IDPRs also exert some dynamical and structural ordering, being much less constrained in their activities than folded proteins. Nuclear magnetic resonance (NMR) spectroscopy is a major technique for the characterization of IDPs, and it can be used for dynamic and structural studies of IDPs. RESULTS AND CONCLUSION This review was carried out to discuss intrinsically disordered proteins and their different goals, as well as the importance and effectiveness of NMR in characterizing intrinsically disordered proteins in healthy and diseased states.
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Affiliation(s)
- Mohamad Hesam Shahrajabian
- National Key Laboratory of Agricultural Microbiology, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Wenli Sun
- National Key Laboratory of Agricultural Microbiology, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
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4
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Clarke RJ. Electrostatic switch mechanisms of membrane protein trafficking and regulation. Biophys Rev 2023; 15:1967-1985. [PMID: 38192346 PMCID: PMC10771482 DOI: 10.1007/s12551-023-01166-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 11/17/2023] [Indexed: 01/10/2024] Open
Abstract
Lipid-protein interactions are normally classified as either specific or general. Specific interactions refer to lipid binding to specific binding sites within a membrane protein, thereby modulating the protein's thermal stability or kinetics. General interactions refer to indirect effects whereby lipids affect membrane proteins by modulating the membrane's physical properties, e.g., its fluidity, thickness, or dipole potential. It is not widely recognized that there is a third distinct type of lipid-protein interaction. Intrinsically disordered N- or C-termini of membrane proteins can interact directly but nonspecifically with the surrounding membrane. Many peripheral membrane proteins are held to the cytoplasmic surface of the plasma membrane via a cooperative combination of two forces: hydrophobic anchoring and electrostatic attraction. An acyl chain, e.g., myristoyl, added post-translationally to one of the protein's termini inserts itself into the lipid matrix and helps hold peripheral membrane proteins onto the membrane. Electrostatic attraction occurs between positively charged basic amino acid residues (lysine and arginine) on one of the protein's terminal tails and negatively charged phospholipid head groups, such as phosphatidylserine. Phosphorylation of either serine or tyrosine residues on the terminal tails via regulatory protein kinases allows for an electrostatic switch mechanism to control trafficking of the protein. Kinase action reduces the positive charge on the protein's tail, weakening the electrostatic attraction and releasing the protein from the membrane. A similar mechanism regulates many integral membrane proteins, but here only electrostatic interactions are involved, and the electrostatic switch modulates protein activity by altering the stabilities of different protein conformational states.
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Affiliation(s)
- Ronald J. Clarke
- School of Chemistry, University of Sydney, Sydney, NSW 2006 Australia
- The University of Sydney Nano Institute, Sydney, NSW 2006 Australia
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5
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A Nanoenzyme Constructed from Manganese and Strandberg-Type Phosphomolybdate with Versatility in Antioxidant and Modulating Conformation of A β Protein Misfolding Aggregates In Vitro. Int J Mol Sci 2023; 24:ijms24054317. [PMID: 36901748 PMCID: PMC10002135 DOI: 10.3390/ijms24054317] [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: 12/21/2022] [Revised: 02/08/2023] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
Amyloid β-peptide (Aβ) misfolding aggregates with β-sheet structures and surplus reactive oxygen species (ROS) are both considered to be the culprit of neuronal toxicity in Alzheimer's disease (AD). Therefore, modulating the misfolding mode of Aβ and inhibiting ROS simultaneous has become an important method for anti-AD. Herein, a nanoscale manganese-substituted polyphosphomolybdate (H2en)3[Mn(H2O)4][Mn(H2O)3]2[P2Mo5O23]2·14.5H2O (abbreviated as MnPM) (en = ethanediamine) was designed and synthesized by single crystal to single crystal transformation method. MnPM can modulate the β-sheet rich conformation of Aβ aggregates, and thus reduce the formation of toxic species. Moreover, MnPM also possesses the ability to eliminate the free radicals produced by Cu2+-Aβ aggregates. It can inhibit the cytotoxicity of β-sheet-rich species and protect synapses of PC12 cells. MnPM combines the conformation modulating ability of Aβ and anti-oxidation ability, which makes a promising multi-funcational molecular with a composite mechanism for the new conceptual designing in treatment of such protein-misfolding diseases.
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6
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Andrews B, Ruggiero T, Urbanc B. How do salt and lipids affect conformational dynamics of Aβ42 monomers in water? Phys Chem Chem Phys 2023; 25:2566-2583. [PMID: 36602150 DOI: 10.1039/d2cp05044g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
It is well established that amyloid β-protein (Aβ) self-assembly is involved in triggering of Alzheimer's disease. On the other hand, evidence of physiological function of Aβ interacting with lipids has only begun to emerge. Details of Aβ-lipid interactions, which may underlie physiological and pathological activities of Aβ, are not well understood. Here, the effects of salt and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipids on conformational dynamics of Aβ42 monomer in water are examined by all-atom molecular dynamics (MD). We acquired six sets of 250 ns long MD trajectories for each of the three lipid concentrations (0, 27, and 109 mM) in the absence and presence of 150 mM salt. Ten replica trajectories per set are used to enhance sampling of Aβ42 conformational space. We show that salt facilitates long-range tertiary contacts in Aβ42, resulting in more compact Aβ42 conformations. By contrast, addition of lipids results in lipid-concentration dependent Aβ42 unfolding concomitant with enhanced stability of the turn in the A21-A30 region. At the high lipid concentration, salt enables the N-terminal region of Aβ42 to form long-range tertiary contacts and interact with lipids, which results in formation of a parallel β-strand. Aβ42 forms stable lipid-protein complexes whereby the protein is adhered to the lipid cluster rather than embedded into it. We propose that the inability of Aβ42 monomer to get embedded into the lipid cluster may be important for facilitating repair of leaks in the blood-brain barrier without penetrating and damaging cellular membranes.
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Affiliation(s)
- Brian Andrews
- Department of Physics, Drexel University, Philadelphia, Pennsylvania, USA.
| | - Thomas Ruggiero
- Department of Physics, Drexel University, Philadelphia, Pennsylvania, USA.
| | - Brigita Urbanc
- Department of Physics, Drexel University, Philadelphia, Pennsylvania, USA.
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7
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Vovk A, Zilman A. Effects of Sequence Composition, Patterning and Hydrodynamics on the Conformation and Dynamics of Intrinsically Disordered Proteins. Int J Mol Sci 2023; 24:1444. [PMID: 36674958 PMCID: PMC9867189 DOI: 10.3390/ijms24021444] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/24/2022] [Accepted: 12/25/2022] [Indexed: 01/13/2023] Open
Abstract
Intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs) perform diverse functions in cellular organization, transport and signaling. Unlike the well-defined structures of the classical natively folded proteins, IDPs and IDRs dynamically span large conformational and structural ensembles. This dynamic disorder impedes the study of the relationship between the amino acid sequences of the IDPs and their spatial structures and dynamics, with different experimental techniques often offering seemingly contradictory results. Although experimental and theoretical evidence indicates that some IDP properties can be understood based on their average biophysical properties and amino acid composition, other aspects of IDP function are dictated by the specifics of the amino acid sequence. We investigate the effects of several key variables on the dimensions and the dynamics of IDPs using coarse-grained polymer models. We focus on the sequence "patchiness" informed by the sequence and biophysical properties of different classes of IDPs-and in particular FG nucleoporins of the nuclear pore complex (NPC). We show that the sequence composition and patterning are well reflected in the global conformational variables such as the radius of gyration and hydrodynamic radius, while the end-to-end distance and dynamics are highly sequence-specific. We find that in good solvent conditions highly heterogeneous sequences of IDPs can be well mapped onto averaged minimal polymer models for the purpose of prediction of the IDPs dimensions and dynamic relaxation times. The coarse-grained simulations are in a good agreement with the results of atomistic MD. We discuss the implications of these results for the interpretation of the recent experimental measurements, and for the further applications of mesoscopic models of FG nucleoporins and IDPs more broadly.
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Affiliation(s)
- Andrei Vovk
- Department of Physics, University of Toronto, 60 St George Street, Toronto, ON M1M 2P7, Canada
| | - Anton Zilman
- Department of Physics, University of Toronto, 60 St George Street, Toronto, ON M1M 2P7, Canada
- Institute for Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9, Canada
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8
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Paik D, Lee H, Kim H, Choi JM. Thermodynamics of π–π Interactions of Benzene and Phenol in Water. Int J Mol Sci 2022; 23:ijms23179811. [PMID: 36077201 PMCID: PMC9456204 DOI: 10.3390/ijms23179811] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022] Open
Abstract
The π–π interaction is a major driving force that stabilizes protein assemblies during protein folding. Recent studies have additionally demonstrated its involvement in the liquid–liquid phase separation (LLPS) of intrinsically disordered proteins (IDPs). As the participating residues in IDPs are exposed to water, π–π interactions for LLPS must be modeled in water, as opposed to the interactions that are often established at the hydrophobic domains of folded proteins. Thus, we investigated the association of free energies of benzene and phenol dimers in water by integrating van der Waals (vdW)-corrected density functional theory (DFT) and DFT in classical explicit solvents (DFT-CES). By comparing the vdW-corrected DFT and DFT-CES results with high-level wavefunction calculations and experimental solvation free energies, respectively, we established the quantitative credibility of these approaches, enabling a reliable prediction of the benzene and phenol dimer association free energies in water. We discovered that solvation influences dimer association free energies, but not significantly when no direct hydrogen-bond-type interaction exists between two monomeric units, which can be explained by the enthalpy–entropy compensation. Our comprehensive computational study of the solvation effect on π–π interactions in water could help us understand the molecular-level driving mechanism underlying the IDP phase behaviors.
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Affiliation(s)
- Dooam Paik
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Hankyul Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Hyungjun Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- Correspondence: (H.K.); (J.-M.C.)
| | - Jeong-Mo Choi
- Department of Chemistry, Pusan National University, Busan 46241, Korea
- Correspondence: (H.K.); (J.-M.C.)
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9
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Molecular basis of the anchoring and stabilization of human islet amyloid polypeptide in lipid hydroperoxidized bilayers. Biochim Biophys Acta Gen Subj 2022; 1866:130200. [PMID: 35820640 DOI: 10.1016/j.bbagen.2022.130200] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 06/25/2022] [Accepted: 07/02/2022] [Indexed: 01/18/2023]
Abstract
The molecular structure of membrane lipids is formed by mono- or polyunsaturations on their aliphatic tails that make them susceptible to oxidation, facilitating the incorporation of hydroperoxide (R-OOH) functional groups. Such groups promote changes in both composition and complexity of the membrane significantly modifying its physicochemical properties. Human Langerhans islets amyloid polypeptide (hIAPP) is the main component of amyloid deposits found in the pancreas of patients with type-2 diabetes (T2D). hIAPP in the presence of membranes with oxidized lipid species accelerates the formation of amyloid fibrils or the formation of intermediate oligomeric structures. However, the molecular bases at the initial stage of the anchoring and stabilization of the hIAPP in a hydroperoxidized membrane are not yet well understood. To shed some light on this matter, in this contribution, three bilayer models were modeled: neutral (POPC), anionic (POPS), and oxidized (POPCOOH), and full atom Molecular Dynamics (MD) simulations were performed. Our results show that the POPCOOH bilayer increases the helicity in hIAPP when compared to POPC or POPS bilayer. The modification in the secondary structure covers the residues of the so-called amyloidogenic core of the hIAPP. Overall, the hydroperoxidation of the neutral lipids modifies both the anchoring and the stabilization of the peptide hIAPP by reducing the random conformations of the peptide and increasing of hydrogen bond population with the hydroperoxidized lipids.
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10
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Haris L, Biehl R, Dulle M, Radulescu A, Holderer O, Hoffmann I, Stadler AM. Variation of Structural and Dynamical Flexibility of Myelin Basic Protein in Response to Guanidinium Chloride. Int J Mol Sci 2022; 23:6969. [PMID: 35805997 PMCID: PMC9266411 DOI: 10.3390/ijms23136969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/18/2022] [Accepted: 06/21/2022] [Indexed: 11/16/2022] Open
Abstract
Myelin basic protein (MBP) is intrinsically disordered in solution and is considered as a conformationally flexible biomacromolecule. Here, we present a study on perturbation of MBP structure and dynamics by the denaturant guanidinium chloride (GndCl) using small-angle scattering and neutron spin-echo spectroscopy (NSE). A concentration of 0.2 M GndCl causes charge screening in MBP resulting in a compact, but still disordered protein conformation, while GndCl concentrations above 1 M lead to structural expansion and swelling of MBP. NSE data of MBP were analyzed using the Zimm model with internal friction (ZIF) and normal mode (NM) analysis. A significant contribution of internal friction was found in compact states of MBP that approaches a non-vanishing internal friction relaxation time of approximately 40 ns at high GndCl concentrations. NM analysis demonstrates that the relaxation rates of internal modes of MBP remain unaffected by GndCl, while structural expansion due to GndCl results in increased amplitudes of internal motions. Within the model of the Brownian oscillator our observations can be rationalized by a loss of friction within the protein due to structural expansion. Our study highlights the intimate coupling of structural and dynamical plasticity of MBP, and its fundamental difference to the behavior of ideal polymers in solution.
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Affiliation(s)
- Luman Haris
- Jülich Centre for Neutron Science (JCNS-1) and Institute of Biological Information Processing (IBI-8), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; (L.H.); (R.B.); (M.D.)
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Ralf Biehl
- Jülich Centre for Neutron Science (JCNS-1) and Institute of Biological Information Processing (IBI-8), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; (L.H.); (R.B.); (M.D.)
| | - Martin Dulle
- Jülich Centre for Neutron Science (JCNS-1) and Institute of Biological Information Processing (IBI-8), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; (L.H.); (R.B.); (M.D.)
| | - Aurel Radulescu
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungzentrum Jülich GmbH, 85747 Garching, Germany; (A.R.); (O.H.)
| | - Olaf Holderer
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungzentrum Jülich GmbH, 85747 Garching, Germany; (A.R.); (O.H.)
| | - Ingo Hoffmann
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, CEDEX 9, 38042 Grenoble, France;
| | - Andreas M. Stadler
- Jülich Centre for Neutron Science (JCNS-1) and Institute of Biological Information Processing (IBI-8), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany; (L.H.); (R.B.); (M.D.)
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
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11
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Mendoza-Martinez C, Papadourakis M, Llabrés S, Gupta AA, Barlow PN, Michel J. Energetics of a protein disorder-order transition in small molecule recognition. Chem Sci 2022; 13:5220-5229. [PMID: 35655546 PMCID: PMC9093188 DOI: 10.1039/d2sc00028h] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 04/01/2022] [Indexed: 12/17/2022] Open
Abstract
Many proteins recognise other proteins via mechanisms that involve the folding of intrinsically disordered regions upon complex formation. Here we investigate how the selectivity of a drug-like small molecule arises from its modulation of a protein disorder-to-order transition. Binding of the compound AM-7209 has been reported to confer order upon an intrinsically disordered ‘lid’ region of the oncoprotein MDM2. Calorimetric measurements revealed that truncation of the lid region of MDM2 increases the apparent dissociation constant of AM-7209 250-fold. By contrast, lid truncation has little effect on the binding of the ligand Nutlin-3a. Insights into these differential binding energetics were obtained via a complete thermodynamic analysis that featured adaptive absolute alchemical free energy of binding calculations with enhanced-sampling molecular dynamics simulations. The simulations reveal that in apo MDM2 the ordered lid state is energetically disfavoured. AM-7209, but not Nutlin-3a, shows a significant energetic preference for ordered lid conformations, thus shifting the balance towards ordering of the lid in the AM-7209/MDM2 complex. The methodology reported herein should facilitate broader targeting of intrinsically disordered regions in medicinal chemistry. Molecular simulations and biophysical measurements elucidate why the ligand AM-7209 orders a disordered region of the protein MDM2 on binding. This work expands strategies available to medicinal chemists for targeting disordered proteins.![]()
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Affiliation(s)
- Cesar Mendoza-Martinez
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Michail Papadourakis
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Salomé Llabrés
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Arun A Gupta
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Paul N Barlow
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Julien Michel
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
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12
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Dogra P, Arya S, Singh AK, Datta A, Mukhopadhyay S. Conformational and Solvation Dynamics of an Amyloidogenic Intrinsically Disordered Domain of a Melanosomal Protein. J Phys Chem B 2022; 126:443-452. [PMID: 34986640 DOI: 10.1021/acs.jpcb.1c09304] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The conformational plasticity of intrinsically disordered proteins (IDPs) allows them to adopt a range of conformational states that can be important for their biological functions. The driving force for the conformational preference of an IDP emanates from an intricate interplay between chain-chain and chain-solvent interactions. Using ultrafast femtosecond and picosecond time-resolved fluorescence measurements, we characterized the conformational and solvation dynamics around the N- and C-terminal segments of a disordered repeat domain of a melanosomal protein Pmel17 that forms functional amyloid responsible for melanin biosynthesis. Our time-resolved fluorescence anisotropy results revealed slight compaction and slower rotational dynamics around the amyloidogenic C-terminal segment when compared to the proline-rich N-terminal segment of the repeat domain. The compaction of the C-terminal region was also associated with the restrained mobility of hydration water as indicated by our solvation dynamics measurements. Our findings indicate that sequence-dependent chain-solvent interactions govern both the conformational and solvation dynamics that are crucial in directing the conversion of a highly dynamic IDP into an ordered amyloid assembly. Such an interplay of amino acid composition-dependent conformational and solvation dynamics might have important physicochemical consequences in specific water-protein, ion-protein, and protein-protein interactions involved in amyloid formation and phase transitions.
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Affiliation(s)
| | | | - Avinash K Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra 400076, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra 400076, India
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13
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Pelus A, Bordes G, Barbe S, Bouchiba Y, Burnard C, Cortés J, Enjalbert B, Esque J, Estaña A, Fauré R, Henras AK, Heux S, Le Men C, Millard P, Nouaille S, Pérochon J, Toanen M, Truan G, Verdier A, Wagner C, Romeo Y, Montanier CY. A tripartite carbohydrate-binding module to functionalize cellulose nanocrystals. Biomater Sci 2021; 9:7444-7455. [PMID: 34647546 DOI: 10.1039/d1bm01156a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The development of protein and microorganism engineering have led to rising expectations of biotechnology in the design of emerging biomaterials, putatively of high interest to reduce our dependence on fossil carbon resources. In this way, cellulose, a renewable carbon based polysaccharide and derived products, displays unique properties used in many industrial applications. Although the functionalization of cellulose is common, it is however limited in terms of number and type of functions. In this work, a Carbohydrate-Binding Module (CBM) was used as a central core to provide a versatile strategy to bring a large diversity of functions to cellulose surfaces. CBM3a from Clostridium thermocellum, which has a high affinity for crystalline cellulose, was flanked through linkers with a streptavidin domain and an azide group introduced through a non-canonical amino acid. Each of these two extra domains was effectively produced and functionalized with a variety of biological and chemical molecules. Structural properties of the resulting tripartite chimeric protein were investigated using molecular modelling approaches, and its potential for the multi-functionalization of cellulose was confirmed experimentally. As a proof of concept, we show that cellulose can be labelled with a fluorescent version of the tripartite protein grafted to magnetic beads and captured using a magnet.
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Affiliation(s)
- Angeline Pelus
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Gaëlle Bordes
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
| | - Sophie Barbe
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Younes Bouchiba
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Callum Burnard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Juan Cortés
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France
| | - Brice Enjalbert
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Jeremy Esque
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | | | - Régis Fauré
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Anthony K Henras
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
| | - Stéphanie Heux
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Claude Le Men
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Pierre Millard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | | | - Julien Pérochon
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Marion Toanen
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Gilles Truan
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Amandine Verdier
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Camille Wagner
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Yves Romeo
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
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14
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Feng CJ, Sinitskiy A, Pande V, Tokmakoff A. Computational IR Spectroscopy of Insulin Dimer Structure and Conformational Heterogeneity. J Phys Chem B 2021; 125:4620-4633. [PMID: 33929849 DOI: 10.1021/acs.jpcb.1c00399] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have investigated the structure and conformational dynamics of insulin dimer using a Markov state model (MSM) built from extensive unbiased atomistic molecular dynamics simulations and performed infrared spectral simulations of the insulin MSM to describe how structural variation within the dimer can be experimentally resolved. Our model reveals two significant conformations to the dimer: a dominant native state consistent with other experimental structures of the dimer and a twisted state with a structure that appears to reflect a ∼55° clockwise rotation of the native dimer interface. The twisted state primarily influences the contacts involving the C-terminus of insulin's B chain, shifting the registry of its intermolecular hydrogen bonds and reorganizing its side-chain packing. The MSM kinetics predict that these configurations exchange on a 14 μs time scale, largely passing through two Markov states with a solvated dimer interface. Computational amide I spectroscopy of site-specifically 13C18O labeled amides indicates that the native and twisted conformation can be distinguished through a series of single and dual labels involving the B24F, B25F, and B26Y residues. Additional structural heterogeneity and disorder is observed within the native and twisted states, and amide I spectroscopy can also be used to gain insight into this variation. This study will provide important interpretive tools for IR spectroscopic investigations of insulin structure and transient IR kinetics experiments studying the conformational dynamics of insulin dimer.
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Affiliation(s)
- Chi-Jui Feng
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
| | - Anton Sinitskiy
- Department of Bioengineering, Stanford University, Stanford, California 94305, United States
| | - Vijay Pande
- Department of Bioengineering, Stanford University, Stanford, California 94305, United States
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
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15
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Wang A, Peng X, Li Y, Zhang D, Zhang Z, Li G. Quality of force fields and sampling methods in simulating pepX peptides: a case study for intrinsically disordered proteins. Phys Chem Chem Phys 2021; 23:2430-2437. [PMID: 33459730 DOI: 10.1039/d0cp05484d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Intrinsically disordered proteins (IDPs) are a group of proteins that lack well-defined structures under native conditions and carry out crucial physiological functions in various biochemical pathways. Due to the heterogeneous nature of IDPs, molecular dynamics simulations have been extensively adopted to investigate the conformational ensembles and dynamic properties of these proteins. However, their accuracy remains limited by the development of force fields and sampling algorithms. Here, we evaluated the quality of both force fields and enhanced sampling algorithms based on five short pepX peptides. Our results show that the more extended conformational ensembles sampled by the AMOEBA polarizable force field present a higher ability to reproduce experimental NMR observables than AMBER and CHARMM classical force fields. Moreover, a better agreement with experiments is achieved in the simulation of IaMD (integrated accelerated molecular dynamics) than in aMD (accelerated molecular dynamics). The results together indicate that the combination of AMOEBA force field and IaMD enhanced sampling might be a better choice for simulating IDPs. This work may provide important clues for developments and applications of force fields and enhanced sampling methods in future simulations of IDPs.
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Affiliation(s)
- Anhui Wang
- State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology, Dalian 116024, China.
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16
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Ding C, Wang S, Zhang Z. Integrating an Enhanced Sampling Method and Small-Angle X-Ray Scattering to Study Intrinsically Disordered Proteins. Front Mol Biosci 2021; 8:621128. [PMID: 34150843 PMCID: PMC8213455 DOI: 10.3389/fmolb.2021.621128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 02/08/2021] [Indexed: 11/23/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) have been paid more and more attention over the past decades because they are involved in a multitude of crucial biological functions. Despite their functional importance, IDPs are generally difficult to investigate because they are very flexible and lack stable structures. Computer simulation may serve as a useful tool in studying IDPs. With the development of computer software and hardware, computational methods, such as molecular dynamics (MD) simulations, are popularly used. However, there is a sampling problem in MD simulations. In this work, this issue is investigated using an IDP called unique long region 11 (UL11), which is the conserved outer tegument component from herpes simplex virus 1. After choosing a proper force field and water model that is suitable for simulating IDPs, integrative modeling by combining an enhanced sampling method and experimental data like small-angle X-ray scattering (SAXS) is utilized to efficiently sample the conformations of UL11. The simulation results are in good agreement with experimental data. This work may provide a general protocol to study structural ensembles of IDPs.
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Affiliation(s)
- Chengtao Ding
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, National Science Center for Physical Sciences at Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | | | - Zhiyong Zhang
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, National Science Center for Physical Sciences at Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
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17
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Klein F, Barrera EE, Pantano S. Assessing SIRAH's Capability to Simulate Intrinsically Disordered Proteins and Peptides. J Chem Theory Comput 2021; 17:599-604. [PMID: 33411518 DOI: 10.1021/acs.jctc.0c00948] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The challenges posed by intrinsically disordered proteins (IDPs) to atomistic and coarse-grained (CG) simulations are boosting efforts to develop and reparametrize current force fields. An assessment of the dynamical behavior of IDPs' and unstructured peptides with the CG SIRAH force field suggests that the current version achieves a fair description of IDPs' conformational flexibility. Moreover, we found a remarkable capability to capture the effect of point mutations in loosely structured peptides.
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Affiliation(s)
- Florencia Klein
- Institut Pasteur de Montevideo, Mataojo 2020, Montevideo, CP 11400, Uruguay.,Graduate Program in Chemistry, Facultad de Química, Universidad de la República, Montevideo 11800, Uruguay
| | - Exequiel E Barrera
- Institut Pasteur de Montevideo, Mataojo 2020, Montevideo, CP 11400, Uruguay.,Instituto de Histología y Embriología (IHEM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), CC56, Universidad Nacional de Cuyo (UNCuyo), M5500 Mendoza, Argentina
| | - Sergio Pantano
- Institut Pasteur de Montevideo, Mataojo 2020, Montevideo, CP 11400, Uruguay.,Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China
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18
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Pramanik U, Chakraborty S, Bhattacharyya K, Mukherjee S. An intrinsically disordered protein in F127 hydrogel: Fluorescence correlation spectroscopy and structural diversity of beta casein. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2020.138105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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19
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Shabane PS, Onufriev AV. Significant compaction of H4 histone tail upon charge neutralization by acetylation and its mimics, possible effects on chromatin structure. J Mol Biol 2020; 433:166683. [PMID: 33096105 DOI: 10.1016/j.jmb.2020.10.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 09/30/2020] [Accepted: 10/13/2020] [Indexed: 10/23/2022]
Abstract
The intrinsically disordered, positively charged H4 histone tail is important for chromatin structure and function. We have explored conformational ensembles of human H4 tail in solution, with varying levels of charge neutralization via acetylation or amino-acid substitutions such as K→Q. We have employed an explicit water model shown recently to be well suited for simulations of intrinsically disordered proteins. Upon progressive neutralization of the H4, its radius of gyration decreases linearly with the tail charge q, the trend is explained using a simple polymer model. While the wild type state (q=+8) is essentially a random coil, hyper-acetylated H4 (q=+3) is virtually as compact and stable as a globular protein of the same number of amino-acids. Conformational ensembles of acetylated H4 match the corresponding K→X substitutions only approximately: based on the ensemble similarity, we propose K→M as a possible alternative to the commonly used K→Q. Possible effects of the H4 tail compaction on chromatin structure are discussed within a qualitative model in which the chromatin is highly heterogeneous, easily inter-converting between various structural forms. We predict that upon progressive charge neutralization of the H4 tail, the least compact sub-states of chromatin de-condense first, followed by de-condensation of more compact structures, e.g. those that harbor a high fraction of stacked di-nucleosomes. The predicted hierarchy of DNA accessibility increase upon progressive acetylation of H4 might be utilized by the cell for selective DNA accessibility control.
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Affiliation(s)
| | - Alexey V Onufriev
- Departments of Computer Science, Virginia Tech, Blacksburg, VA 24060, United States; Department of Physics, Virginia Tech, Blacksburg, VA 24060, United States; Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, USA.
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20
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Characterization of partially ordered states in the intrinsically disordered N-terminal domain of p53 using millisecond molecular dynamics simulations. Sci Rep 2020; 10:12402. [PMID: 32709860 PMCID: PMC7382488 DOI: 10.1038/s41598-020-69322-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 07/08/2020] [Indexed: 12/14/2022] Open
Abstract
The exploration of intrinsically disordered proteins in isolation is a crucial step to understand their complex dynamical behavior. In particular, the emergence of partially ordered states has not been explored in depth. The experimental characterization of such partially ordered states remains elusive due to their transient nature. Molecular dynamics mitigates this limitation thanks to its capability to explore biologically relevant timescales while retaining atomistic resolution. Here, millisecond unbiased molecular dynamics simulations were performed in the exemplar N-terminal region of p53. In combination with state-of-the-art Markov state models, simulations revealed the existence of several partially ordered states accounting for [Formula: see text] 40% of the equilibrium population. Some of the most relevant states feature helical conformations similar to the bound structure of p53 to Mdm2, as well as novel [Formula: see text]-sheet elements. This highlights the potential complexity underlying the energy surface of intrinsically disordered proteins.
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21
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Rieloff E, Skepö M. Phosphorylation of a Disordered Peptide-Structural Effects and Force Field Inconsistencies. J Chem Theory Comput 2020; 16:1924-1935. [PMID: 32050065 DOI: 10.1021/acs.jctc.9b01190] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Phosphorylation is one of the most abundant types of post-translational modifications of intrinsically disordered proteins (IDPs). This study examines the conformational changes in the 15-residue-long N-terminal fragment of the IDP statherin upon phosphorylation, using computer simulations with two different force fields: AMBER ff99SB-ILDN and CHARMM36m. The results from the simulations are compared with experimental small-angle X-ray scattering (SAXS) and circular dichroism data. In the unphosphorylated state, the two force fields are in excellent agreement regarding global structural properties such as size and shape. However, they exhibit some differences in the extent and type of the secondary structure. In the phosphorylated state, neither of the force fields performs well compared to the experimental data. Both force fields show a compaction of the peptide upon phosphorylation, greater than what is seen in SAXS experiments, although they differ in the local structure. While the CHARMM force field increases the fraction of bends in the peptide as a response to strong interactions between the phosphorylated residues and arginines, the AMBER force field shows an increase of the helical content in the N-terminal part of the peptide, where the phosphorylated residues reside, in better agreement with circular dichroism results.
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Affiliation(s)
- Ellen Rieloff
- Division of Theoretical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Marie Skepö
- Division of Theoretical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.,LINXS-Lund Institute of Advanced Neutron and X-ray Science, Scheelevägen 19, SE-223 70 Lund, Sweden
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22
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Lucas HR, Fernández RD. Navigating the dynamic landscape of alpha-synuclein morphology: a review of the physiologically relevant tetrameric conformation. Neural Regen Res 2020; 15:407-415. [PMID: 31571649 PMCID: PMC6921358 DOI: 10.4103/1673-5374.265792] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
N-acetylated α-synuclein (αSyn) has long been established as an intrinsically disordered protein associated with a dysfunctional role in Parkinson's disease. In recent years, a physiologically relevant, higher order conformation has been identified as a helical tetramer that is tailored by buried hydrophobic interactions and is distinctively aggregation resistant. The canonical mechanism by which the tetramer assembles remains elusive. As novel biochemical approaches, computational methods, pioneering purification platforms, and powerful imaging techniques continue to develop, puzzling information that once sparked debate as to the veracity of the tetramer has now shed light upon this new counterpart in αSyn neurobiology. Nuclear magnetic resonance and computational studies on multimeric αSyn structure have revealed that the protein folding propensity is controlled by small energy barriers that enable large scale reconfiguration. Alternatively, familial mutations ablate tetramerization and reconfigure polymorphic fibrillization. In this review, we will discuss the dynamic landscape of αSyn quaternary structure with a focus on the tetrameric conformation.
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Affiliation(s)
- Heather R Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, USA
| | - Ricardo D Fernández
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, USA
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23
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Feng CJ, Dhayalan B, Tokmakoff A. Refinement of Peptide Conformational Ensembles by 2D IR Spectroscopy: Application to Ala‒Ala‒Ala. Biophys J 2019; 114:2820-2832. [PMID: 29925019 DOI: 10.1016/j.bpj.2018.05.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 04/27/2018] [Accepted: 05/02/2018] [Indexed: 10/28/2022] Open
Abstract
Characterizing ensembles of intrinsically disordered proteins is experimentally challenging because of the ill-conditioned nature of ensemble determination with limited data and the intrinsic fast dynamics of the conformational ensemble. Amide I two-dimensional infrared (2D IR) spectroscopy has picosecond time resolution to freeze structural ensembles as needed for probing disordered-protein ensembles and conformational dynamics. Also, developments in amide I computational spectroscopy now allow a quantitative and direct prediction of amide I spectra based on conformational distributions drawn from molecular dynamics simulations, providing a route to ensemble refinement against experimental spectra. We performed a Bayesian ensemble refinement method on Ala-Ala-Ala against isotope-edited Fourier-transform infrared spectroscopy and 2D IR spectroscopy and tested potential factors affecting the quality of ensemble refinements. We found that isotope-edited 2D IR spectroscopy provides a stringent constraint on Ala-Ala-Ala conformations and returns consistent conformational ensembles with the dominant ppII conformer across varying prior distributions from many molecular dynamics force fields and water models. The dominant factor influencing ensemble refinements is the systematic frequency uncertainty from spectroscopic maps. However, the uncertainty of conformer populations can be significantly reduced by incorporating 2D IR spectra in addition to traditional Fourier-transform infrared spectra. Bayesian ensemble refinement against isotope-edited 2D IR spectroscopy thus provides a route to probe equilibrium-complex protein ensembles and potentially nonequilibrium conformational dynamics.
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Affiliation(s)
- Chi-Jui Feng
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois
| | - Balamurugan Dhayalan
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois.
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24
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Kuhn AJ, Raskatov JA. Using mirror-image peptides to enhance robustness and reproducibility in studying the amyloid β-protein. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 168:57-67. [PMID: 31699327 DOI: 10.1016/bs.pmbts.2019.05.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Alzheimer's disease, the most common form of dementia, is a devastating disease that affects over 44 million people worldwide. One etiological agent of Alzheimer's, the amyloid β-protein (Aβ), is an aggregation-prone, intrinsically disordered peptide that can form a wide variety of aggregates. The pathways by which Aβ aggregates in order to exert its toxicity, referred to as the Amyloid Cascade, remains largely elusive despite substantial deconvolution efforts. Preparing high-quality material that exhibits reproducible biophysical characteristics has proven challenging. Herein, we propose that mirror-image peptides can be used to rigorously control Aβ preparation quality.
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Affiliation(s)
- Ariel J Kuhn
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, United States
| | - Jevgenij A Raskatov
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, United States.
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25
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Shabane PS, Izadi S, Onufriev AV. General Purpose Water Model Can Improve Atomistic Simulations of Intrinsically Disordered Proteins. J Chem Theory Comput 2019; 15:2620-2634. [PMID: 30865832 DOI: 10.1021/acs.jctc.8b01123] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Unconstrained atomistic simulations of intrinsically disordered proteins and peptides (IDP) remain a challenge: widely used, "general purpose" water models tend to favor overly compact structures relative to experiment. Here we have performed a total of 93 μs of unrestrained MD simulations to explore, in the context of IDPs, a recently developed "general-purpose" 4-point rigid water model OPC, which describes liquid state of water close to experiment. We demonstrate that OPC, together with a popular AMBER force field ff99SB, offers a noticeable improvement over TIP3P in producing more realistic structural ensembles of three common IDPs benchmarks: 55-residue apo N-terminal zinc-binding domain of HIV-1 integrase ("protein IN"), amyloid β-peptide (Aβ42) (residues 1-42), and 26-reside H4 histone tail. As a negative control, computed folding profile of a regular globular miniprotein (CLN025) in OPC water is in appreciably better agreement with experiment than that obtained in TIP3P, which tends to overstabilize the compact native state relative to the extended conformations. We employed Aβ42 peptide to investigate the possible influence of the solvent box size on simulation outcomes. We advocate a cautious approach for simulations of IDPs: we suggest that the solvent box size should be at least four times the radius of gyration of the random coil corresponding to the IDP. The computed free energy landscape of protein IN in OPC resembles a shallow "tub" - conformations with substantially different degrees of compactness that are within 2 kB T of each other. Conformations with very different secondary structure content coexist within 1 kB T of the global free energy minimum. States with higher free energy tend to have less secondary structure. Computed low helical content of the protein has virtually no correlation with its degree of compactness, which calls into question the possibility of using the helicity as a metric for assessing performance of water models for IDPs, when the helicity is low. Predicted radius of gyration ( R g) of H4 histone tail in OPC water falls in-between that of a typical globular protein and a fully denatured protein of the same size; the predicted R g is consistent with two independent predictions. In contrast, H4 tail in TIP3P water is as compact as the corresponding globular protein. The computed free energy landscape of H4 tail in OPC is relatively flat over a significant range of compactness, which, we argue, is consistent with its biological function as facilitator of internucleosome interactions.
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Affiliation(s)
| | - Saeed Izadi
- Early Stage Pharmaceutical Development , Genentech Inc. , South San Francisco , California 94080 , United States
| | - Alexey V Onufriev
- Department of Computer Science , Virginia Tech , Blacksburg , Virginia 24060 , United States.,Center for Soft Matter and Biological Physics , Virginia Tech , Blacksburg , Virginia 24061 , United States
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26
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Molecular simulation of peptides coming of age: Accurate prediction of folding, dynamics and structures. Arch Biochem Biophys 2019; 664:76-88. [DOI: 10.1016/j.abb.2019.01.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 01/23/2019] [Accepted: 01/28/2019] [Indexed: 12/24/2022]
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27
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Rieloff E, Tully MD, Skepö M. Assessing the Intricate Balance of Intermolecular Interactions upon Self-Association of Intrinsically Disordered Proteins. J Mol Biol 2019; 431:511-523. [DOI: 10.1016/j.jmb.2018.11.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/12/2018] [Accepted: 11/28/2018] [Indexed: 12/01/2022]
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28
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Trumbore CN. Shear-induced amyloid formation of IDPs in the brain. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 166:225-309. [DOI: 10.1016/bs.pmbts.2019.05.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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29
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Uversky VN. Protein intrinsic disorder and structure-function continuum. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 166:1-17. [DOI: 10.1016/bs.pmbts.2019.05.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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30
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Wu H, Wolynes PG, Papoian GA. AWSEM-IDP: A Coarse-Grained Force Field for Intrinsically Disordered Proteins. J Phys Chem B 2018; 122:11115-11125. [PMID: 30091924 PMCID: PMC6713210 DOI: 10.1021/acs.jpcb.8b05791] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The associative memory, water-mediated, structure and energy model (AWSEM) has been successfully used to study protein folding, binding, and aggregation problems. In this work, we introduce AWSEM-IDP, a new AWSEM branch for simulating intrinsically disordered proteins (IDPs), where the weights of the potentials determining secondary structure formation have been finely tuned, and a novel potential is introduced that helps to precisely control both the average extent of protein chain collapse and the chain's fluctuations in size. AWSEM-IDP can efficiently sample large conformational spaces, while retaining sufficient molecular accuracy to realistically model proteins. We applied this new model to two IDPs, demonstrating that AWSEM-IDP can reasonably well reproduce higher-resolution reference data, thus providing the foundation for a transferable IDP force field. Finally, we used thermodynamic perturbation theory to show that, in general, the conformational ensembles of IDPs are highly sensitive to fine-tuning of force field parameters.
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Affiliation(s)
- Hao Wu
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
| | - Peter G. Wolynes
- Departments of Chemistry and Physics and Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - Garegin A. Papoian
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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31
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Vymětal J, Jurásková V, Vondrášek J. AMBER and CHARMM Force Fields Inconsistently Portray the Microscopic Details of Phosphorylation. J Chem Theory Comput 2018; 15:665-679. [PMID: 30468703 DOI: 10.1021/acs.jctc.8b00715] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Phosphorylation of serine, threonine, and tyrosine is one of the most frequently occurring and crucial post-translational modifications of proteins often associated with important structural and functional changes. We investigated the direct effect of phosphorylation on the intrinsic conformational preferences of amino acids as a potential trigger of larger structural events. We conducted a comparative study of force fields on terminally capped amino acids (dipeptides) as the simplest model for phosphorylation. Our bias-exchange metadynamics simulations revealed that all model dipeptides sampled a great heterogeneity of ensembles affected by introduction of mono- and dianionic phosphate groups. However, the detected changes in populations of backbone conformers and side-chain rotamers did not reveal a strong discriminatory shift in preferences, as could be anticipated for the bulky, charged phosphate group. Furthermore, the AMBER and CHARMM force fields provided inconsistent populations of individual conformers as well as net structural trends upon phosphorylation. Detailed analysis of ensembles revealed competition between hydration and formation of internal hydrogen bonds involving amide hydrogens and the phosphate group. The observed difference in hydration free energy and potential for hydrogen bonding in individual force fields could be attributed to the different partial atomic charges used in each force field and, hence, the different parametrization strategies. Nevertheless, conformational propensities and net structural changes upon phosphorylation are difficult to extract from experimental measurements, and existing experimental data provide limited guidance for force field assessment and further development.
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Affiliation(s)
- Jiří Vymětal
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , Flemingovo náměstí 542/2 , 166 10 Praha 6 , Czech Republic
| | - Veronika Jurásková
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , Flemingovo náměstí 542/2 , 166 10 Praha 6 , Czech Republic
| | - Jiří Vondrášek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , Flemingovo náměstí 542/2 , 166 10 Praha 6 , Czech Republic
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32
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Bhasne K, Mukhopadhyay S. Formation of Heterotypic Amyloids: α-Synuclein in Co-Aggregation. Proteomics 2018; 18:e1800059. [PMID: 30216674 DOI: 10.1002/pmic.201800059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/28/2018] [Indexed: 12/13/2022]
Abstract
Protein misfolding resulting in the formation of ordered amyloid aggregates is associated with a number of devastating human diseases. Intrinsically disordered proteins (IDPs) do not autonomously fold up into a unique stable conformation and remain as an ensemble of rapidly fluctuating conformers. Many IDPs are prone to convert into the β-rich amyloid state. One such amyloidogenic IDP is α-synuclein that is involved in Parkinson's disease. Recent studies have indicated that other neuronal proteins, especially IDPs, can co-aggregate with α-synuclein in many pathological ailments. This article describes several such observations highlighting the role of heterotypic protein-protein interactions in the formation of hetero-amyloids. It is believed that the characterizations of molecular cross talks between amyloidogenic proteins as well as the mechanistic studies of heterotypic protein aggregation will allow us to decipher the role of the interacting proteins in amyloid proteomics.
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Affiliation(s)
- Karishma Bhasne
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India.,Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India.,Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India
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33
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Uversky VN. Flexibility of the "rigid" classics or rugged bottom of the folding funnels of myoglobin, lysozyme, RNase A, chymotrypsin, cytochrome c, and carboxypeptidase A1. INTRINSICALLY DISORDERED PROTEINS 2018; 5:e1355205. [PMID: 30250772 DOI: 10.1080/21690707.2017.1355205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 07/08/2017] [Indexed: 10/18/2022]
Abstract
The abilities to crystalize of a globular protein and to solve its crystal structure seem to represent triumph of the lock-and-key model of protein functionality, where the presence of unique 3D structure resembling aperiodic crystal is considered as a prerequisite for a given protein to possess specific biologic activity. The history of protein crystallography has its roots in first crystal structures of myoglobin, lysozyme, RNase A, chymotrypsin, cytochrome c, and carboxypeptidase A1 solved more than 50 y ago. This article briefly considers extensive structural information currently available for these proteins and shows that the bottoms of their folding funnels (i.e., the lowest parts of their potential energy landscapes) are not smoothed but rugged. In other words, these crystallization classics are characterized by significant conformational flexibility and are not rigid (immobile) crystal-like entities.
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Affiliation(s)
- Vladimir N Uversky
- Department of Molecular Medicine, USF Health Byrd Alzheimer Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Russia
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34
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Diaz D, Clarke RJ. Evolutionary Analysis of the Lysine-Rich N-terminal Cytoplasmic Domains of the Gastric H +,K +-ATPase and the Na +,K +-ATPase. J Membr Biol 2018; 251:653-666. [PMID: 30056551 DOI: 10.1007/s00232-018-0043-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/19/2018] [Indexed: 12/16/2022]
Abstract
The catalytic α-subunits of both the Na+,K+-ATPase and the gastric H+,K+-ATPase possess lysine-rich N-termini which project into the cytoplasm. Due to conflicting experimental results, it is currently unclear whether the N-termini play a role in ion pump function or regulation, and, if they do, by what mechanism. Comparison of the lysine frequencies of the N-termini of both proteins with those of all of their extramembrane domains showed that the N-terminal lysine frequencies are far higher than one would expect simply from exposure to the aqueous solvent. The lysine frequency was found to vary significantly between different vertebrate classes, but this is due predominantly to a change in N-terminal length. As evidenced by a comparison between fish and mammals, an evolutionary trend towards an increase of the length of the N-terminus of the H+,K+-ATPase on going from an ancestral fish to mammals could be identified. This evolutionary trend supports the hypothesis that the N-terminus is important in ion pump function or regulation. In placental mammals, one of the lysines is replaced by serine (Ser-27), which is a target for protein kinase C. In most other animal species, a lysine occupies this position and hence no protein kinase C target is present. Interaction with protein kinase C is thus not the primary role of the lysine-rich N-terminus. The disordered structure of the N-terminus may, via increased flexibility, facilitate interaction with another binding partner, e.g. the surrounding membrane, or help to stabilise particular enzyme conformations via the increased entropy it produces.
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Affiliation(s)
- Dil Diaz
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia. .,The University of Sydney Nano Institute, Sydney, NSW, 2006, Australia.
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35
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Dong X, Qiao Q, Qian Z, Wei G. Recent computational studies of membrane interaction and disruption of human islet amyloid polypeptide: Monomers, oligomers and protofibrils. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018. [PMID: 29530482 DOI: 10.1016/j.bbamem.2018.03.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The amyloid deposits of human islet amyloid polypeptide (hIAPP) are found in type 2 diabetes patients. hIAPP monomer is intrinsically disordered in solution, whereas it can form amyloid fibrils both in vivo and in vitro. Extensive evidence suggests that hIAPP causes the disruption of cellular membrane, and further induces cytotoxicity and the death of islet β-cells in pancreas. The presence of membrane also accelerates the hIAPP fibril formation. hIAPP oligomers and protofibrils in the early stage of aggregation were reported to be the most cytotoxic, disrupting the membrane integrity and giving rise to the pathological process. The detailed molecular mechanisms of hIAPP-membrane interactions and membrane disruption are complex and remain mostly unknown. Here in this review, we focus on recent computational studies that investigated the interactions of full length and fragmentary hIAPP monomers, oligomers and protofibrils with anionic, zwitterionic and mixed anionic-zwitterionic lipid bilayers. We mainly discuss the binding orientation of monomers at membrane surface, the conformational ensemble and the oligomerization of hIAPP inside membranes, the effect of lipid composition on hIAPP oligomers/protofibrils-membrane interactions, and the hIAPP-induced membrane perturbation. This review provides mechanistic insights into the interactions between hIAPP and lipid bilayers with different lipid composition at an atomistic level, which is helpful to understand the hIAPP cytotoxicity mediated by membrane. This article is part of a Special Issue entitled: Protein Aggregation and Misfolding at the Cell Membrane Interface edited by Ayyalusamy Ramamoorthy.
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Affiliation(s)
- Xuewei Dong
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Science (Ministry of Education), Collaborative Innovation Center of Advanced Microstructures (Nanjing), Fudan University, Shanghai 200433, China
| | - Qin Qiao
- Digital Medical Research Center, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; Shanghai Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention, Shanghai 200032, China.
| | - Zhenyu Qian
- Key Laboratory of Exercise and Health Sciences (Ministry of Education) and School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Science (Ministry of Education), Collaborative Innovation Center of Advanced Microstructures (Nanjing), Fudan University, Shanghai 200433, China.
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36
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Ameseder F, Radulescu A, Khaneft M, Lohstroh W, Stadler AM. Homogeneous and heterogeneous dynamics in native and denatured bovine serum albumin. Phys Chem Chem Phys 2018; 20:5128-5139. [DOI: 10.1039/c7cp08292d] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Quasielastic incoherent neutron spectroscopy experiments reveal that chemical denaturation significantly modifies the internal dynamics of bovine serum albumin.
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Affiliation(s)
- Felix Ameseder
- Jülich Centre for Neutron Science JCNS and Institute for Complex Systems ICS
- Forschungszentrum Jülich GmbH
- 52425 Jülich
- Germany
| | - Aurel Radulescu
- Jülich Centre for Neutron Science JCNS
- Forschungszentrum Jülich GmbH, Outstation at MLZ
- 85747 Garching
- Germany
| | - Marina Khaneft
- Jülich Centre for Neutron Science JCNS
- Forschungszentrum Jülich GmbH, Outstation at MLZ
- 85747 Garching
- Germany
| | - Wiebke Lohstroh
- Heinz Maier-Leibnitz Zentrum
- Technische Universität München
- 85747 Garching
- Germany
| | - Andreas M. Stadler
- Jülich Centre for Neutron Science JCNS and Institute for Complex Systems ICS
- Forschungszentrum Jülich GmbH
- 52425 Jülich
- Germany
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37
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Majumdar A, Mukhopadhyay S. Fluorescence Depolarization Kinetics to Study the Conformational Preference, Structural Plasticity, Binding, and Assembly of Intrinsically Disordered Proteins. Methods Enzymol 2018; 611:347-381. [DOI: 10.1016/bs.mie.2018.09.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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38
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Using chirality to probe the conformational dynamics and assembly of intrinsically disordered amyloid proteins. Sci Rep 2017; 7:12433. [PMID: 28970487 PMCID: PMC5624888 DOI: 10.1038/s41598-017-10525-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 08/09/2017] [Indexed: 12/22/2022] Open
Abstract
Intrinsically disordered protein (IDP) conformers occupy large regions of conformational space and display relatively flat energy surfaces. Amyloid-forming IDPs, unlike natively folded proteins, have folding trajectories that frequently involve movements up shallow energy gradients prior to the “downhill” folding leading to fibril formation. We suggest that structural perturbations caused by chiral inversions of amino acid side-chains may be especially valuable in elucidating these pathways of IDP folding. Chiral inversions are subtle in that they do not change side-chain size, flexibility, hydropathy, charge, or polarizability. They allow focus to be placed solely on the question of how changes in amino acid side-chain orientation, and the resultant alterations in peptide backbone structure, affect a peptide’s conformational landscape (Ramachandran space). If specific inversions affect folding and assembly, then the sites involved likely are important in mediating these processes. We suggest here a “focused chiral mutant library” approach for the unbiased study of amyloid-forming IDPs.
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39
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Warren C, Shechter D. Fly Fishing for Histones: Catch and Release by Histone Chaperone Intrinsically Disordered Regions and Acidic Stretches. J Mol Biol 2017; 429:2401-2426. [PMID: 28610839 DOI: 10.1016/j.jmb.2017.06.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 06/05/2017] [Accepted: 06/06/2017] [Indexed: 01/21/2023]
Abstract
Chromatin is the complex of eukaryotic DNA and proteins required for the efficient compaction of the nearly 2-meter-long human genome into a roughly 10-micron-diameter cell nucleus. The fundamental repeating unit of chromatin is the nucleosome: 147bp of DNA wrapped about an octamer of histone proteins. Nucleosomes are stable enough to organize the genome yet must be dynamically displaced and reassembled to allow access to the underlying DNA for transcription, replication, and DNA damage repair. Histone chaperones are a non-catalytic group of proteins that are central to the processes of nucleosome assembly and disassembly and thus the fluidity of the ever-changing chromatin landscape. Histone chaperones are responsible for binding the highly basic histone proteins, shielding them from non-specific interactions, facilitating their deposition onto DNA, and aiding in their eviction from DNA. Although most histone chaperones perform these common functions, recent structural studies of many different histone chaperones reveal that there are few commonalities in their folds. Importantly, sequence-based predictions show that histone chaperones are highly enriched in intrinsically disordered regions (IDRs) and acidic stretches. In this review, we focus on the molecular mechanisms underpinning histone binding, selectivity, and regulation of these highly dynamic protein regions. We highlight new evidence suggesting that IDRs are often critical for histone chaperone function and play key roles in chromatin assembly and disassembly pathways.
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Affiliation(s)
- Christopher Warren
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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40
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Watts CR, Gregory AJ, Frisbie CP, Lovas S. Structural properties of amyloid β(1-40) dimer explored by replica exchange molecular dynamics simulations. Proteins 2017; 85:1024-1045. [PMID: 28241387 DOI: 10.1002/prot.25270] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 01/25/2017] [Accepted: 02/12/2017] [Indexed: 12/17/2022]
Abstract
Replica exchange molecular dynamics simulations (300 ns) were used to study the dimerization of amyloid β(1-40) (Aβ(1-40)) polypeptide. Configurational entropy calculations revealed that at physiological temperature (310 K, 37°C) dynamic dimers are formed by randomly docked monomers. Free energy of binding of the two chains to each other was -93.56 ± 6.341 kJ mol-1 . Prevalence of random coil conformations was found for both chains with the exceptions of increased β-sheet content from residues 16-21 and 29-32 of chain A and residues 15-21 and 30-33 of chain B with β-turn/β-bend conformations in both chains from residues 1-16, 21-29 of chain A, 1-16, and 21-29 of chain B. There is a mixed β-turn/β-sheet region from residues 33-38 of both chains. Analysis of intra- and interchain residue distances shows that, although the individual chains are highly flexible, the dimer system stays in a loosely packed antiparallel β-sheet configuration with contacts between residues 17-21 of chain A with residues 17-21 and 31-36 of chain B as well as residues 31-36 of chain A with residues 17-21 and 31-36 of chain B. Based on dihedral principal component analysis, the antiparallel β-sheet-loop-β-sheet conformational motif is favored for many low energy sampled conformations. Our results show that Aβ(1-40) can form dynamic dimers in aqueous solution that have significant conformational flexibility and are stabilized by collapse of the central and C-terminal hydrophobic cores with the expected β-sheet-loop-β-sheet conformational motif. Proteins 2017; 85:1024-1045. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Charles R Watts
- Department of Neurosurgery, Mayo Clinic, College of Medicine, Rochester, Minnesota, 55905.,Department of Neurosurgery, Mayo Clinic Health System, La Crosse, Wisconsin, 54601
| | - Andrew J Gregory
- Department of Neurosurgery, Mayo Clinic Health System, La Crosse, Wisconsin, 54601
| | - Cole P Frisbie
- Department of Neurosurgery, Mayo Clinic Health System, La Crosse, Wisconsin, 54601.,Department of Biomedical Sciences, Creighton University, Omaha, Nebraska, 61718
| | - Sándor Lovas
- Department of Biomedical Sciences, Creighton University, Omaha, Nebraska, 61718
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41
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Burger VM, Vandervelde A, Hendrix J, Konijnenberg A, Sobott F, Loris R, Stultz CM. Hidden States within Disordered Regions of the CcdA Antitoxin Protein. J Am Chem Soc 2017; 139:2693-2701. [PMID: 28124913 DOI: 10.1021/jacs.6b11450] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The bacterial toxin-antitoxin system CcdB-CcdA provides a mechanism for the control of cell death and quiescence. The antitoxin protein CcdA is a homodimer composed of two monomers that each contain a folded N-terminal region and an intrinsically disordered C-terminal arm. Binding of the intrinsically disordered C-terminal arm of CcdA to the toxin CcdB prevents CcdB from inhibiting DNA gyrase and thereby averts cell death. Accurate models of the unfolded state of the partially disordered CcdA antitoxin can therefore provide insight into general mechanisms whereby protein disorder regulates events that are crucial to cell survival. Previous structural studies were able to model only two of three distinct structural states, a closed state and an open state, that are adopted by the C-terminal arm of CcdA. Using a combination of free energy simulations, single-pair Förster resonance energy transfer experiments, and existing NMR data, we developed structural models for all three states of the protein. Contrary to prior studies, we find that CcdA samples a previously unknown state where only one of the disordered C-terminal arms makes extensive contacts with the folded N-terminal domain. Moreover, our data suggest that previously unobserved conformational states play a role in regulating antitoxin concentrations and the activity of CcdA's cognate toxin. These data demonstrate that intrinsic disorder in CcdA provides a mechanism for regulating cell fate.
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Affiliation(s)
| | - Alexandra Vandervelde
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel , B-1050 Brussels, Belgium.,Molecular Recognition Unit, Structural Biology Research Center, Vlaams Instituut voor Biotechnologie , B-1050 Brussels, Belgium
| | - Jelle Hendrix
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, University of Leuven , B-3000 Leuven, Belgium.,Faculty of Medicine and Life Sciences and Biomedical Research Institute, Hasselt University , B-3500 Hasselt, Belgium
| | - Albert Konijnenberg
- Biomolecular & Analytical Mass Spectrometry, Department of Chemistry, University of Antwerp , B-2020 Antwerp, Belgium
| | - Frank Sobott
- Biomolecular & Analytical Mass Spectrometry, Department of Chemistry, University of Antwerp , B-2020 Antwerp, Belgium
| | - Remy Loris
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel , B-1050 Brussels, Belgium.,Molecular Recognition Unit, Structural Biology Research Center, Vlaams Instituut voor Biotechnologie , B-1050 Brussels, Belgium
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42
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p53 Proteoforms and Intrinsic Disorder: An Illustration of the Protein Structure-Function Continuum Concept. Int J Mol Sci 2016; 17:ijms17111874. [PMID: 27834926 PMCID: PMC5133874 DOI: 10.3390/ijms17111874] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/27/2016] [Accepted: 11/03/2016] [Indexed: 01/10/2023] Open
Abstract
Although it is one of the most studied proteins, p53 continues to be an enigma. This protein has numerous biological functions, possesses intrinsically disordered regions crucial for its functionality, can form both homo-tetramers and isoform-based hetero-tetramers, and is able to interact with many binding partners. It contains numerous posttranslational modifications, has several isoforms generated by alternative splicing, alternative promoter usage or alternative initiation of translation, and is commonly mutated in different cancers. Therefore, p53 serves as an important illustration of the protein structure–function continuum concept, where the generation of multiple proteoforms by various mechanisms defines the ability of this protein to have a multitude of structurally and functionally different states. Considering p53 in the light of a proteoform-based structure–function continuum represents a non-canonical and conceptually new contemplation of structure, regulation, and functionality of this important protein.
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43
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Pancsa R, Tompa P. Coding Regions of Intrinsic Disorder Accommodate Parallel Functions. Trends Biochem Sci 2016; 41:898-906. [DOI: 10.1016/j.tibs.2016.08.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 08/16/2016] [Accepted: 08/19/2016] [Indexed: 02/01/2023]
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44
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Kukharenko O, Sawade K, Steuer J, Peter C. Using Dimensionality Reduction to Systematically Expand Conformational Sampling of Intrinsically Disordered Peptides. J Chem Theory Comput 2016; 12:4726-4734. [DOI: 10.1021/acs.jctc.6b00503] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
| | - Kevin Sawade
- Theoretical
Chemistry, University of Konstanz, 78547 Konstanz, Germany
| | - Jakob Steuer
- Theoretical
Chemistry, University of Konstanz, 78547 Konstanz, Germany
| | - Christine Peter
- Theoretical
Chemistry, University of Konstanz, 78547 Konstanz, Germany
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45
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A Structure-free Method for Quantifying Conformational Flexibility in proteins. Sci Rep 2016; 6:29040. [PMID: 27358108 PMCID: PMC4928179 DOI: 10.1038/srep29040] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/08/2016] [Indexed: 11/24/2022] Open
Abstract
All proteins sample a range of conformations at physiologic temperatures and this inherent flexibility enables them to carry out their prescribed functions. A comprehensive understanding of protein function therefore entails a characterization of protein flexibility. Here we describe a novel approach for quantifying a protein’s flexibility in solution using small-angle X-ray scattering (SAXS) data. The method calculates an effective entropy that quantifies the diversity of radii of gyration that a protein can adopt in solution and does not require the explicit generation of structural ensembles to garner insights into protein flexibility. Application of this structure-free approach to over 200 experimental datasets demonstrates that the methodology can quantify a protein’s disorder as well as the effects of ligand binding on protein flexibility. Such quantitative descriptions of protein flexibility form the basis of a rigorous taxonomy for the description and classification of protein structure.
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46
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Wei G, Xi W, Nussinov R, Ma B. Protein Ensembles: How Does Nature Harness Thermodynamic Fluctuations for Life? The Diverse Functional Roles of Conformational Ensembles in the Cell. Chem Rev 2016; 116:6516-51. [PMID: 26807783 PMCID: PMC6407618 DOI: 10.1021/acs.chemrev.5b00562] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
All soluble proteins populate conformational ensembles that together constitute the native state. Their fluctuations in water are intrinsic thermodynamic phenomena, and the distributions of the states on the energy landscape are determined by statistical thermodynamics; however, they are optimized to perform their biological functions. In this review we briefly describe advances in free energy landscape studies of protein conformational ensembles. Experimental (nuclear magnetic resonance, small-angle X-ray scattering, single-molecule spectroscopy, and cryo-electron microscopy) and computational (replica-exchange molecular dynamics, metadynamics, and Markov state models) approaches have made great progress in recent years. These address the challenging characterization of the highly flexible and heterogeneous protein ensembles. We focus on structural aspects of protein conformational distributions, from collective motions of single- and multi-domain proteins, intrinsically disordered proteins, to multiprotein complexes. Importantly, we highlight recent studies that illustrate functional adjustment of protein conformational ensembles in the crowded cellular environment. We center on the role of the ensemble in recognition of small- and macro-molecules (protein and RNA/DNA) and emphasize emerging concepts of protein dynamics in enzyme catalysis. Overall, protein ensembles link fundamental physicochemical principles and protein behavior and the cellular network and its regulation.
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Affiliation(s)
- Guanghong Wei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Wenhui Xi
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
- Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
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47
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Burger VM, Nolasco DO, Stultz CM. Expanding the Range of Protein Function at the Far End of the Order-Structure Continuum. J Biol Chem 2016; 291:6706-13. [PMID: 26851282 PMCID: PMC4807258 DOI: 10.1074/jbc.r115.692590] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The traditional view of the structure-function paradigm is that a protein's function is inextricably linked to a well defined, three-dimensional structure, which is determined by the protein's primary amino acid sequence. However, it is now accepted that a number of proteins do not adopt a unique tertiary structure in solution and that some degree of disorder is required for many proteins to perform their prescribed functions. In this review, we highlight how a number of protein functions are facilitated by intrinsic disorder and introduce a new protein structure taxonomy that is based on quantifiable metrics of a protein's disorder.
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Affiliation(s)
- Virginia M Burger
- From the Research Laboratory for Electronics, Department of Electrical Engineering & Computer Science, and
| | - Diego O Nolasco
- From the Research Laboratory for Electronics, Department of Electrical Engineering & Computer Science, and
| | - Collin M Stultz
- From the Research Laboratory for Electronics, Department of Electrical Engineering & Computer Science, and the Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138
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