1
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Lihan M, Tajkhorshid E. Improved Highly Mobile Membrane Mimetic Model for Investigating Protein-Cholesterol Interactions. J Chem Inf Model 2024; 64:4822-4834. [PMID: 38844760 DOI: 10.1021/acs.jcim.4c00619] [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: 06/25/2024]
Abstract
Cholesterol (CHL) plays an integral role in modulating the function and activity of various mammalian membrane proteins. Due to the slow dynamics of lipids, conventional computational studies of protein-CHL interactions rely on either long-time scale atomistic simulations or coarse-grained approximations to sample the process. A highly mobile membrane mimetic (HMMM) has been developed to enhance lipid diffusion and thus used to facilitate the investigation of lipid interactions with peripheral membrane proteins and, with customized in silico solvents to replace phospholipid tails, with integral membrane proteins. Here, we report an updated HMMM model that is able to include CHL, a nonphospholipid component of the membrane, henceforth called HMMM-CHL. To this end, we had to optimize the effect of the customized solvents on CHL behavior in the membrane. Furthermore, the new solvent is compatible with simulations using force-based switching protocols. In the HMMM-CHL, both improved CHL dynamics and accelerated lipid diffusion are integrated. To test the updated model, we have applied it to the characterization of protein-CHL interactions in two membrane protein systems, the human β2-adrenergic receptor (β2AR) and the mitochondrial voltage-dependent anion channel 1 (VDAC-1). Our HMMM-CHL simulations successfully identified CHL binding sites and captured detailed CHL interactions in excellent consistency with experimental data as well as other simulation results, indicating the utility of the improved model in applications where an enhanced sampling of protein-CHL interactions is desired.
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Affiliation(s)
- Muyun Lihan
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
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2
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Makasewicz K, Linse S, Sparr E. Interplay of α-synuclein with Lipid Membranes: Cooperative Adsorption, Membrane Remodeling and Coaggregation. JACS AU 2024; 4:1250-1262. [PMID: 38665673 PMCID: PMC11040681 DOI: 10.1021/jacsau.3c00579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/18/2024] [Accepted: 01/18/2024] [Indexed: 04/28/2024]
Abstract
α-Synuclein is a small neuronal protein enriched at presynaptic termini. It is hypothesized to play a role in neurotransmitter release and synaptic vesicle cycling, while the formation of α-synuclein amyloid fibrils is associated with several neurodegenerative diseases, most notably Parkinson's Disease. The molecular mechanisms of both the physiological and pathological functions of α-synuclein remain to be fully understood, but in both cases, interactions with membranes play an important role. In this Perspective, we discuss several aspects of α-synuclein interactions with lipid membranes including cooperative adsorption, membrane remodeling and α-synuclein amyloid fibril formation in the presence of lipid membranes. We highlight the coupling between the different phenomena and their interplay in the context of physiological and pathological functions of α-synuclein.
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Affiliation(s)
- Katarzyna Makasewicz
- Division
of Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-22100 Lund, Sweden
| | - Sara Linse
- Biochemistry
and Structural Biology, Lund University, SE-22100 Lund, Sweden
| | - Emma Sparr
- Department
of Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden
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3
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Onishi N, Mazzaferro N, Kunstelj Š, Alvarado DA, Muller AM, Vázquez FX. Flanking Domains Modulate α-Synuclein Monomer Structure: A Molecular Dynamics Domain Deletion Study. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.23.586267. [PMID: 38586052 PMCID: PMC10996548 DOI: 10.1101/2024.03.23.586267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Aggregates of misfolded α-synuclein proteins (asyn) are key markers of Parkinson's disease. Asyn proteins have three domains: an N-terminal domain, a hydrophobic NAC core implicated in aggregation, and a proline-rich C-terminal domain. Proteins with truncated C-terminal domains are known to be prone to aggregation and suggest that studying domain-domain interactions in asyn monomers could help elucidate the role of the flanking domains in modulating protein structure. To this end, we used Gaussian accelerated molecular dynamics (GAMD) to simulate wild-type (WT), N-terminal truncated (DN), C-terminal truncated (ΔC), and isolated NAC domain variants (isoNAC). Using clustering and contact analysis, we found that N- and C-terminal domains interact via electrostatic interactions, while the NAC and N-terminal domains interact through hydrophobic contacts. Our work also suggests that the C-terminal domain does not interact directly with the NAC domain but instead interacts with the N-terminal domain. Removal of the N-terminal domain led to increased contacts between NAC and C-terminal domains and the formation of interdomain β-sheets. Removal of either flanking domain also resulted in increased compactness of every domain. We also found that the contacts between flanking domains results in an electrostatic potential (ESP) that could possibly lead to favorable interactions with anionic lipid membranes. Removal of the C-terminal domain disrupts the ESP in a way that is likely to over-stabilize protein-membrane interactions. All of this suggests that one of the roles of the flanking domains may be to modulate the protein structure in a way that helps maintain elongation, hide hydrophobic residue from the solvent, and maintain an ESP that aids favorable interactions with the membrane.
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Affiliation(s)
- Noriyo Onishi
- Department of Chemistry, St. John’s University, Queens, NY 11439, USA
| | | | - Špela Kunstelj
- Department of Chemistry, St. John’s University, Queens, NY 11439, USA
| | - Daisy A. Alvarado
- Department of Chemistry, St. John’s University, Queens, NY 11439, USA
| | - Anna M. Muller
- Department of Chemistry, St. John’s University, Queens, NY 11439, USA
| | - Frank X. Vázquez
- Department of Chemistry, St. John’s University, Queens, NY 11439, USA
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4
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Maurer M, Lazaridis T. Transmembrane β-Barrel Models of α-Synuclein Oligomers. J Chem Inf Model 2023; 63:7171-7179. [PMID: 37963823 DOI: 10.1021/acs.jcim.3c00997] [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: 11/16/2023]
Abstract
The aggregation of α-synuclein is implicated in a number of neurodegenerative diseases, such as Parkinson's and Multiple System Atrophy, but the role of these aggregates in disease development is not clear. One possible mechanism of cytotoxicity is the disturbance or permeabilization of cell membranes by certain types of oligomers. However, no high-resolution structure of such membrane-embedded complexes has ever been determined. Here we construct and evaluate putative transmembrane β-barrels formed by this protein. Examination of the α-synuclein sequence reveals two regions that could form membrane-embedded β-hairpins: 64-92 (the NAC), and 35-56, which harbors many familial Parkinson's mutations. The stability of β-barrels formed by these hairpins is examined first in implicit membrane pores and then by multimicrosecond all-atom simulations. We find that a NAC region barrel remains stably inserted and hydrated for at least 10 μs. A 35-56 barrel remains stably inserted in the membrane but dehydrates and collapses if all His50 are neutral or if His50 is replaced by Q. If half of the His50 are doubly protonated, the barrel takes an oval shape but remains hydrated for at least 10 μs. Possible implications of these findings for α-synuclein pathology are discussed.
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Affiliation(s)
- Manuela Maurer
- Department of Chemistry & Biochemistry, City College of New York/CUNY, 160 Convent Ave, New York, New York 10031, United States
| | - Themis Lazaridis
- Department of Chemistry & Biochemistry, City College of New York/CUNY, 160 Convent Ave, New York, New York 10031, United States
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5
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Zhang Y, Soubias O, Pant S, Heinrich F, Vogel A, Li J, Li Y, Clifton LA, Daum S, Bacia K, Huster D, Randazzo PA, Lösche M, Tajkhorshid E, Byrd RA. Myr-Arf1 conformational flexibility at the membrane surface sheds light on the interactions with ArfGAP ASAP1. Nat Commun 2023; 14:7570. [PMID: 37989735 PMCID: PMC10663523 DOI: 10.1038/s41467-023-43008-5] [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: 05/12/2023] [Accepted: 10/30/2023] [Indexed: 11/23/2023] Open
Abstract
ADP-ribosylation factor 1 (Arf1) interacts with multiple cellular partners and membranes to regulate intracellular traffic, organelle structure and actin dynamics. Defining the dynamic conformational landscape of Arf1 in its active form, when bound to the membrane, is of high functional relevance and key to understanding how Arf1 can alter diverse cellular processes. Through concerted application of nuclear magnetic resonance (NMR), neutron reflectometry (NR) and molecular dynamics (MD) simulations, we show that, while Arf1 is anchored to the membrane through its N-terminal myristoylated amphipathic helix, the G domain explores a large conformational space, existing in a dynamic equilibrium between membrane-associated and membrane-distal conformations. These configurational dynamics expose different interfaces for interaction with effectors. Interaction with the Pleckstrin homology domain of ASAP1, an Arf-GTPase activating protein (ArfGAP), restricts motions of the G domain to lock it in what seems to be a conformation exposing functionally relevant regions.
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Affiliation(s)
- Yue Zhang
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA
- Ring Therapeutics, Inc., Cambridge, MA, USA
| | - Olivier Soubias
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA
| | - Shashank Pant
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Loxo Oncology at Lilly, Louisville, CO, USA
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
- NIST Center for Neutron Research, Gaithersburg, MD, USA
| | - Alexander Vogel
- Institute of Medical Physics and Biophysics, University of Leipzig, 04107, Leipzig, Germany
| | - Jess Li
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA
| | - Yifei Li
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA
- Vonsun Pharmatech Co., Ltd., Suzhou, China
| | - Luke A Clifton
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot, Oxfordshire, OX11 0QX, UK
| | - Sebastian Daum
- Institute for Chemistry, Department of Biophysical Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3A, 06120, Halle, Germany
| | - Kirsten Bacia
- Institute for Chemistry, Department of Biophysical Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3A, 06120, Halle, Germany
| | - Daniel Huster
- Institute of Medical Physics and Biophysics, University of Leipzig, 04107, Leipzig, Germany
| | - Paul A Randazzo
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
- NIST Center for Neutron Research, Gaithersburg, MD, USA
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - R Andrew Byrd
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA.
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6
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Dou T, Matveyenka M, Kurouski D. Elucidation of Secondary Structure and Toxicity of α-Synuclein Oligomers and Fibrils Grown in the Presence of Phosphatidylcholine and Phosphatidylserine. ACS Chem Neurosci 2023; 14:3183-3191. [PMID: 37603792 PMCID: PMC10862479 DOI: 10.1021/acschemneuro.3c00314] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 08/09/2023] [Indexed: 08/23/2023] Open
Abstract
Abrupt aggregation of α-synuclein (α-Syn) in the midbrain hypothalamus and thalamus is a hallmark of Parkinson's disease (PD), the fastest growing neurodegenerative pathology, projected to strike 12 million people by 2040 worldwide. In this study, we examine the effect of two phospholipids that are present in neuronal membranes, phosphatidylcholine (PC) and phosphatidylserine (PS), on the rate of α-Syn aggregation. We found that PS accelerated α-Syn aggregation, whereas PC strongly inhibited α-Syn aggregation. We also utilized the nano-infrared imaging technique, also known as atomic force microscopy infrared (AFM-IR) spectroscopy, to investigate whether PC and PS only change the rates or also modify the secondary structure of α-Syn aggregates. We found that both phospholipids uniquely altered the secondary structure of α-Syn aggregates present at the lag and growth phase, as well as the late stage of protein aggregation. In addition, compared to the α-Syn aggregates formed in the lipid-free environment, α-Syn:PC and α-Syn:PS aggregates demonstrated higher cellular toxicity to N27 rat neurons. Interestingly, both α-Syn:PC and α-Syn:PS aggregates showed similar levels of oxidative stress, but α-Syn:PC aggregates exhibited a greater degree of mitochondrial dysfunction compared to α-Syn:PS aggregates.
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Affiliation(s)
- Tianyi Dou
- Department
of Biochemistry and Biophysics, Texas A&M
University, College
Station, Texas 77843, United States
| | - Mikhail Matveyenka
- Department
of Biochemistry and Biophysics, Texas A&M
University, College
Station, Texas 77843, United States
| | - Dmitry Kurouski
- Department
of Biochemistry and Biophysics, Texas A&M
University, College
Station, Texas 77843, United States
- Department
of Biomedical Engineering, Texas A&M
University, College Station, Texas 77843, United States
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7
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Saurabh A, Prabhu NP. Concerted enhanced-sampling simulations to elucidate the helix-fibril transition pathway of intrinsically disordered α-Synuclein. Int J Biol Macromol 2022; 223:1024-1041. [PMID: 36379279 DOI: 10.1016/j.ijbiomac.2022.11.079] [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: 08/18/2022] [Revised: 10/19/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022]
Abstract
Fibril formation of α-synuclein is linked with Parkinson's disease. The intrinsically disordered nature of α-syn provides extensive conformational plasticity and becomes difficult to characterize its transition pathway from native monomeric to disease-associated fibril form. We implemented different simulation methods such as steered dynamics-umbrella sampling, and replica-exchange and conventional MD simulations to access various conformational states of α-syn. Nineteen distinct intermediate structures were identified by free energy landscape and cluster analysis. They were then sorted based on secondary structure and solvent exposure of fibril-core residues to illustrate the fibril dissociation pathway. The analysis showed that following the initial dissociation of the polypeptide chain from the fibril, α-syn might form either compact-conformations by long-range interactions or extended-conformations stabilized by local interactions. This leads α-syn to adapt two different pathways. The secondary structure, solvation, contact distance, interaction energies and backbone dihedrals of thirty-two selected residues were analyzed for all the 19 intermediates. The results suggested that formation of β-turns, reorganization of salt bridges, and dihedral changes in the hydrophobic regions are the major driving forces for helix-fibril transition. Structural features of the intermediates also correlated with the earlier experimental and computational studies. The study provides critical information on the fibrillation pathway of α-syn.
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Affiliation(s)
- Archi Saurabh
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - N Prakash Prabhu
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
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8
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Muller MP, Morrissey JH, Tajkhorshid E. Molecular View into Preferential Binding of the Factor VII Gla Domain to Phosphatidic Acid. Biochemistry 2022; 61:1694-1703. [PMID: 35853076 PMCID: PMC9637449 DOI: 10.1021/acs.biochem.2c00266] [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] [Indexed: 11/28/2022]
Abstract
Factor VII (FVII) is a serine protease with a key role in initiating the coagulation cascade. It is part of a family of vitamin K-dependent clotting proteins, which require vitamin K for formation of their specialized membrane-binding domains (Gla domains). Membrane binding of the FVII Gla domain is critical to the activity of FVII, mediating the formation of its complex with other clotting factors. While Gla domains among coagulation factors are highly conserved in terms of amino acid sequence and structure, they demonstrate differential binding specificity toward anionic lipids. Although most Gla domain-containing clotting proteins display a strong preference for phosphatidylserine (PS), it has been demonstrated that FVII and protein C instead bind preferentially to phosphatidic acid (PA). We have developed the first model of the FVII Gla domain bound to PA lipids in membranes containing PA, the highly mobile membrane mimetic model, which accelerates slow diffusion of lipids in molecular dynamics simulations and therefore facilitates the membrane binding process and enhances sampling of lipid interactions. Simulations were performed using atomic level molecular dynamics, requiring a fixed charge to all atoms. The overall charge assigned to each PA lipid for this study was -1. We also developed an additional model of the FVII Gla domain bound to a 1:1 PS/PC membrane and compared the modes of binding of PS and PA lipids to FVII, allowing us to identify potential PA-specific binding sites.
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Affiliation(s)
- Melanie P Muller
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - James H Morrissey
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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9
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Vermaas JV, Mayne CG, Shinn E, Tajkhorshid E. Assembly and Analysis of Cell-Scale Membrane Envelopes. J Chem Inf Model 2022; 62:602-617. [PMID: 34910495 PMCID: PMC8903035 DOI: 10.1021/acs.jcim.1c01050] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The march toward exascale computing will enable routine molecular simulation of larger and more complex systems, for example, simulation of entire viral particles, on the scale of approximately billions of atoms─a simulation size commensurate with a small bacterial cell. Anticipating the future hardware capabilities that will enable this type of research and paralleling advances in experimental structural biology, efforts are currently underway to develop software tools, procedures, and workflows for constructing cell-scale structures. Herein, we describe our efforts in developing and implementing an efficient and robust workflow for construction of cell-scale membrane envelopes and embedding membrane proteins into them. A new approach for construction of massive membrane structures that are stable during the simulations is built on implementing a subtractive assembly technique coupled with the development of a structure concatenation tool (fastmerge), which eliminates overlapping elements based on volumetric criteria rather than adding successive molecules to the simulation system. Using this approach, we have constructed two "protocells" consisting of MARTINI coarse-grained beads to represent cellular membranes, one the size of a cellular organelle and another the size of a small bacterial cell. The membrane envelopes constructed here remain whole during the molecular dynamics simulations performed and exhibit water flux only through specific proteins, demonstrating the success of our methodology in creating tight cell-like membrane compartments. Extended simulations of these cell-scale structures highlight the propensity for nonspecific interactions between adjacent membrane proteins leading to the formation of protein microclusters on the cell surface, an insight uniquely enabled by the scale of the simulations. We anticipate that the experiences and best practices presented here will form the basis for the next generation of cell-scale models, which will begin to address the addition of soluble proteins, nucleic acids, and small molecules essential to the function of a cell.
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Affiliation(s)
- Josh V. Vermaas
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401
| | - Christopher G. Mayne
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Eric Shinn
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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10
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Puentes LN, Lengyel-Zhand Z, Lee JY, Hsieh CJ, Schneider ME, Edwards KJ, Luk KC, Lee VMY, Trojanowski JQ, Mach RH. Poly (ADP-ribose) Interacts With Phosphorylated α-Synuclein in Post Mortem PD Samples. Front Aging Neurosci 2021; 13:704041. [PMID: 34220490 PMCID: PMC8249773 DOI: 10.3389/fnagi.2021.704041] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 05/26/2021] [Indexed: 12/12/2022] Open
Abstract
Poly (ADP-ribose) (PAR) is a negatively charged polymer that is biosynthesized by Poly (ADP-ribose) Polymerase-1 (PARP-1) and regulates various cellular processes. Alpha-synuclein (αSyn) is an intrinsically disordered protein (IDP) that has been directly implicated with driving the onset and progression of Parkinson's disease (PD). The mechanisms by which α-synuclein (αSyn) elicits its neurotoxic effects remain unclear, though it is well established that the main components of Lewy bodies (LBs) and Lewy neurites (LNs) in PD patients are aggregated hyperphosphorylated (S129) forms of αSyn (pαSyn). In the present study, we used immunofluorescence-based assays to explore if PARP-1 enzymatic product (PAR) promotes the aberrant cytoplasmic accumulation of pαSyn. We also performed quantitative measurements using in situ proximity ligation assays (PLA) on a transgenic murine model of α-synucleinopathy (M83-SNCA∗A53T) and post mortem PD/PDD patient samples to characterize PAR-pαSyn interactions. Additionally, we used bioinformatic approaches and site-directed mutagenesis to identify PAR-binding regions on αSyn. In summary, our studies show that PAR-pαSyn interactions are predominantly observed in PD-relevant transgenic murine models of αSyn pathology and post mortem PD/PDD patient samples. Moreover, we confirm that the interactions between PAR and αSyn involve electrostatic forces between negatively charged PAR and lysine residues on the N-terminal region of αSyn.
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Affiliation(s)
- Laura N. Puentes
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Zsofia Lengyel-Zhand
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Ji Youn Lee
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Chia-Ju Hsieh
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Mark E. Schneider
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Kimberly J. Edwards
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Kelvin C. Luk
- Department of Pathology and Laboratory Medicine, Institute on Aging and Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Virginia M.-Y. Lee
- Department of Pathology and Laboratory Medicine, Institute on Aging and Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - John Q. Trojanowski
- Department of Pathology and Laboratory Medicine, Institute on Aging and Center for Neurodegenerative Disease Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Robert H. Mach
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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11
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Baratam K, Jha K, Srivastava A. Flexible pivoting of dynamin pleckstrin homology domain catalyzes fission: insights into molecular degrees of freedom. Mol Biol Cell 2021; 32:1306-1319. [PMID: 33979205 PMCID: PMC8351549 DOI: 10.1091/mbc.e20-12-0794] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The neuronal dynamin1 functions in the release of synaptic vesicles by orchestrating the process of GTPase-dependent membrane fission. Dynamin1 associates with the plasma membrane–localized phosphatidylinositol-4,5-bisphosphate (PIP2) through the centrally located pleckstrin homology domain (PHD). The PHD is dispensable as fission (in model membranes) can be managed, even when the PHD-PIP2 interaction is replaced by a generic polyhistidine- or polylysine-lipid interaction. However, the absence of the PHD renders a dramatic dampening of the rate of fission. These observations suggest that the PHD-PIP2–containing membrane interaction could have evolved to expedite fission to fulfill the requirement of rapid kinetics of synaptic vesicle recycling. Here, we use a suite of multiscale modeling approaches to explore PHD–membrane interactions. Our results reveal that 1) the binding of PHD to PIP2-containing membranes modulates the lipids toward fission-favoring conformations and softens the membrane, and 2) PHD associates with membrane in multiple orientations using variable loops as pivots. We identify a new loop (VL4), which acts as an auxiliary pivot and modulates the orientation flexibility of PHD on the membrane—a mechanism that we believe may be important for high-fidelity dynamin collar assembly. Together, these insights provide a molecular-level understanding of the catalytic role of PHD in dynamin-mediated membrane fission.
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Affiliation(s)
| | - Kirtika Jha
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore-560012, India
| | - Anand Srivastava
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore-560012, India
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12
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Amos SBA, Schwarz TC, Shi J, Cossins BP, Baker TS, Taylor RJ, Konrat R, Sansom MSP. Membrane Interactions of α-Synuclein Revealed by Multiscale Molecular Dynamics Simulations, Markov State Models, and NMR. J Phys Chem B 2021; 125:2929-2941. [PMID: 33719460 PMCID: PMC8006134 DOI: 10.1021/acs.jpcb.1c01281] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/01/2021] [Indexed: 01/30/2023]
Abstract
α-Synuclein (αS) is a presynaptic protein that binds to cell membranes and is linked to Parkinson's disease (PD). Binding of αS to membranes is a likely first step in the molecular pathophysiology of PD. The αS molecule can adopt multiple conformations, being largely disordered in water, adopting a β-sheet conformation when present in amyloid fibrils, and forming a dynamic multiplicity of α-helical conformations when bound to lipid bilayers and related membrane-mimetic surfaces. Multiscale molecular dynamics simulations in conjunction with nuclear magnetic resonance (NMR) and cross-linking mass spectrometry (XLMS) measurements are used to explore the interactions of αS with an anionic lipid bilayer. The simulations and NMR measurements together reveal a break in the helical structure of the central non-amyloid-β component (NAC) region of αS in the vicinity of residues 65-70, which may facilitate subsequent oligomer formation. Coarse-grained simulations of αS starting from the structure of αS when bound to a detergent micelle reveal the overall pattern of protein contacts to anionic lipid bilayers, while subsequent all-atom simulations provide details of conformational changes upon membrane binding. In particular, simulations and NMR data for liposome-bound αS indicate incipient β-strand formation in the NAC region, which is supported by intramolecular contacts seen via XLMS and simulations. Markov state models based on the all-atom simulations suggest a mechanism of conformational change of membrane-bound αS via a dynamic helix break in the region of residue 65 in the NAC region. The emergent dynamic model of membrane-interacting αS advances our understanding of the mechanism of PD, potentially aiding the design of novel therapeutic approaches.
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Affiliation(s)
- Sarah-Beth
T. A. Amos
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
| | - Thomas C. Schwarz
- Department
of Structural and Computational
Biology, Max Perutz Laboratories, University
of Vienna, Campus Vienna
Biocenter 5, Vienna A-1030, Austria
| | - Jiye Shi
- UCB
Pharma, 208 Bath Road, Slough SL1 3WE, U.K.
| | | | | | | | - Robert Konrat
- Department
of Structural and Computational
Biology, Max Perutz Laboratories, University
of Vienna, Campus Vienna
Biocenter 5, Vienna A-1030, Austria
| | - Mark S. P. Sansom
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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13
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Gorgun D, Lihan M, Kapoor K, Tajkhorshid E. Binding mode of SARS-CoV-2 fusion peptide to human cellular membrane. Biophys J 2021; 120:2914-2926. [PMID: 33675757 PMCID: PMC7929786 DOI: 10.1016/j.bpj.2021.02.041] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 01/29/2021] [Accepted: 02/15/2021] [Indexed: 01/08/2023] Open
Abstract
Infection of human cells by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) relies on its binding to a specific receptor and subsequent fusion of the viral and host cell membranes. The fusion peptide (FP), a short peptide segment in the spike protein, plays a central role in the initial penetration of the virus into the host cell membrane, followed by the fusion of the two membranes. Here, we use an array of molecular dynamics simulations that take advantage of the highly mobile membrane mimetic model to investigate the interaction of the SARS-CoV2 FP with a lipid bilayer representing mammalian cellular membranes at an atomic level and to characterize the membrane-bound form of the peptide. Six independent systems were generated by changing the initial positioning and orientation of the FP with respect to the membrane, and each system was simulated in five independent replicas, each for 300 ns. In 73% of the simulations, the FP reaches a stable, membrane-bound configuration, in which the peptide deeply penetrated into the membrane. Clustering of the results reveals three major membrane-binding modes (binding modes 1-3), in which binding mode 1 populates over half of the data points. Taking into account the sequence conservation among the viral FPs and the results of mutagenesis studies establishing the role of specific residues in the helical portion of the FP in membrane association, the significant depth of penetration of the whole peptide, and the dense population of the respective cluster, we propose that the most deeply inserted membrane-bound form (binding mode 1) represents more closely the biologically relevant form. Analysis of FP-lipid interactions shows the involvement of specific residues, previously described as the "fusion-active core residues," in membrane binding. Taken together, the results shed light on a key step involved in SARS-CoV2 infection, with potential implications in designing novel inhibitors.
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Affiliation(s)
- Defne Gorgun
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Muyun Lihan
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Karan Kapoor
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
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14
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Hicks A, Escobar CA, Cross TA, Zhou HX. Fuzzy Association of an Intrinsically Disordered Protein with Acidic Membranes. JACS AU 2021; 1:66-78. [PMID: 33554215 PMCID: PMC7851954 DOI: 10.1021/jacsau.0c00039] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Indexed: 05/03/2023]
Abstract
Many physiological and pathophysiological processes, including Mycobacterium tuberculosis (Mtb) cell division, may involve fuzzy membrane association by proteins via intrinsically disordered regions. The fuzziness is extreme when the conformation and pose of the bound protein and the composition of the proximal lipids are all highly dynamic. Here, we tackled the challenge in characterizing the extreme fuzzy membrane association of the disordered, cytoplasmic N-terminal region (NT) of ChiZ, an Mtb divisome protein, by combining solution and solid-state NMR spectroscopy and molecular dynamics simulations. While membrane-associated NT does not gain any secondary structure, its interactions with lipids are not random, but formed largely by Arg residues predominantly in the second, conserved half of the NT sequence. As NT frolics on the membrane, lipids quickly redistribute, with acidic lipids, relative to zwitterionic lipids, preferentially taking up Arg-proximal positions. The asymmetric engagement of NT arises partly from competition between acidic lipids and acidic residues, all in the first half of NT, for Arg interactions. This asymmetry is accentuated by membrane insertion of the downstream transmembrane helix. This type of semispecific molecular recognition may be a general mechanism by which disordered proteins target membranes.
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Affiliation(s)
- Alan Hicks
- Institute
of Molecular Biophysics, Department of Physics, and Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- Department
of Chemistry and Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Cristian A. Escobar
- Institute
of Molecular Biophysics, Department of Physics, and Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Timothy A. Cross
- Institute
of Molecular Biophysics, Department of Physics, and Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Huan-Xiang Zhou
- Department
of Chemistry and Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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15
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Kang C, Sun R. Molecular Dynamics Study of the Interaction between the N-terminal of α-Synuclein and a Lipid Bilayer Mimicking Synaptic Vesicles. J Phys Chem B 2020; 125:1036-1048. [DOI: 10.1021/acs.jpcb.0c08620] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Christopher Kang
- Department of Chemistry, University of Hawai’i at Manoa, 2545 McCarthy
Mall, Honolulu 96822-2275, Hawaii, United States
| | - Rui Sun
- Department of Chemistry, University of Hawai’i at Manoa, 2545 McCarthy
Mall, Honolulu 96822-2275, Hawaii, United States
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16
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Cai B, Liu J, Zhao Y, Xu X, Bu B, Li D, Zhang L, Dong W, Ji B, Diao J. Single-vesicle imaging quantifies calcium's regulation of nanoscale vesicle clustering mediated by α-synuclein. MICROSYSTEMS & NANOENGINEERING 2020; 6:38. [PMID: 34567651 PMCID: PMC8433175 DOI: 10.1038/s41378-020-0147-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/18/2020] [Accepted: 02/03/2020] [Indexed: 06/13/2023]
Abstract
Although numerous studies have shown that the protein α-synuclein (α-Syn) plays a central role in Parkinson's disease, dementia with Lewy bodies, and other neurodegenerative diseases, the protein's physiological function remains poorly understood. Furthermore, despite recent reports suggesting that, under the influence of Ca2+, α-Syn can interact with synaptic vesicles, the mechanisms underlying that interaction are far from clear. Thus, we used single-vesicle imaging to quantify the extent to which Ca2+ regulates nanoscale vesicle clustering mediated by α-Syn. Our results revealed not only that vesicle clustering required α-Syn to bind to anionic lipid vesicles, but also that different concentrations of Ca2+ exerted different effects on how α-Syn induced vesicle clustering. In particular, low concentrations of Ca2+ inhibited vesicle clustering by blocking the electrostatic interaction between the lipid membrane and the N terminus of α-Syn, whereas high concentrations promoted vesicle clustering, possibly due to the electrostatic interaction between Ca2+ and the negatively charged lipids that is independent of α-Syn. Taken together, our results provide critical insights into α-Syn's physiological function, and how Ca2+ regulates vesicle clustering mediated by α-Syn.
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Affiliation(s)
- Bin Cai
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267 USA
| | - Jie Liu
- Biomechanics and Biomaterials Laboratory, Department of Applied Mechanics, Beijing Institute of Technology, Beijing, 100081 China
| | - Yunfei Zhao
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000 China
| | - Xiangyu Xu
- Biomechanics and Biomaterials Laboratory, Department of Applied Mechanics, Beijing Institute of Technology, Beijing, 100081 China
| | - Bing Bu
- Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 China
| | - Dechang Li
- Institute of Applied Mechanics, Department of Engineering Mechanics, Zhejiang University, Hangzhou, 310027 China
| | - Lei Zhang
- Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter (Ministry of Education), School of Science, Xi’an Jiaotong University, Xi’an, 710049 China
| | - Wei Dong
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000 China
| | - Baohua Ji
- Institute of Applied Mechanics, Department of Engineering Mechanics, Zhejiang University, Hangzhou, 310027 China
- Beijing Advanced Innovation Center for Biomedical Engineering, Beijing, 100191 China
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267 USA
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17
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Pant S, Tajkhorshid E. Microscopic Characterization of GRP1 PH Domain Interaction with Anionic Membranes. J Comput Chem 2020; 41:489-499. [PMID: 31762060 PMCID: PMC7000246 DOI: 10.1002/jcc.26109] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/03/2019] [Accepted: 10/15/2019] [Indexed: 01/17/2023]
Abstract
The pleckstrin homology (PH) domain of general receptor for phosphoionositides 1 (GRP1-PHD) binds specifically to phosphatidylinositol (3,4,5)-triphosphate (PIP3 ), and acts as a second messenger. Using an extensive array of molecular dynamics (MD) simulations employing highly mobile membrane mimetic (HMMM) model as well as complementary full membrane simulations, we capture differentiable binding and dynamics of GRP1-PHD in the presence of membranes containing PC, PS, and PIP3 lipids in varying compositions. While GRP1-PHD forms only transient interactions with pure PC membranes, incorporation of anionic lipids resulted in stable membrane-bound configurations. We report the first observation of two distinct PIP3 binding modes on GRP1-PHD, involving PIP3 interactions at a "canonical" and at an "alternate" site, suggesting the possibility of simultaneous binding of multiple anionic lipids. The full membrane simulations confirmed the stability of the membrane bound pose of GRP1-PHD as captured from our HMMM membrane binding simulations. By performing additional steered membrane unbinding simulations and calculating nonequilibrium work associated with the process, as well as metadynamics simulations, on the protein bound to full membranes, allowing for more quantitative examination of the binding strength of the GRP1-PHD to the membrane, we demonstrate that along with the bound PIP3 , surrounding anionic PS lipids increase the energetic cost of unbinding of GRP1-PHD from the canonical mode, causing them to dissociate more slowly than the alternate mode. Our results demonstrate that concurrent binding of multiple anionic lipids by GRP1-PHD contributes to its membrane affinity, which in turn control its signaling activity. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Shashank Pant
- Center for Biophysics and Quantitative Biology, Department of Biochemistry, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, Department of Biochemistry, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801
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18
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Loschwitz J, Olubiyi OO, Hub JS, Strodel B, Poojari CS. Computer simulations of protein-membrane systems. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 170:273-403. [PMID: 32145948 PMCID: PMC7109768 DOI: 10.1016/bs.pmbts.2020.01.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The interactions between proteins and membranes play critical roles in signal transduction, cell motility, and transport, and they are involved in many types of diseases. Molecular dynamics (MD) simulations have greatly contributed to our understanding of protein-membrane interactions, promoted by a dramatic development of MD-related software, increasingly accurate force fields, and available computer power. In this chapter, we present available methods for studying protein-membrane systems with MD simulations, including an overview about the various all-atom and coarse-grained force fields for lipids, and useful software for membrane simulation setup and analysis. A large set of case studies is discussed.
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Affiliation(s)
- Jennifer Loschwitz
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
| | - Olujide O Olubiyi
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany; Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany
| | - Birgit Strodel
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
| | - Chetan S Poojari
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany.
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19
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Coskuner O, Uversky VN. Intrinsically disordered proteins in various hypotheses on the pathogenesis of Alzheimer's and Parkinson's diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 166:145-223. [PMID: 31521231 DOI: 10.1016/bs.pmbts.2019.05.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Amyloid-β (Aβ) and α-synuclein (αS) are two intrinsically disordered proteins (IDPs) at the centers of the pathogenesis of Alzheimer's and Parkinson's diseases, respectively. Different hypotheses have been proposed for explanation of the molecular mechanisms of the pathogenesis of these two diseases, with these two IDPs being involved in many of these hypotheses. Currently, we do not know, which of these hypothesis is more accurate. Experiments face challenges due to the rapid conformational changes, fast aggregation processes, solvent and paramagnetic effects in studying these two IDPs in detail. Furthermore, pathological modifications impact their structures and energetics. Theoretical studies using computational chemistry and computational biology have been utilized to understand the structures and energetics of Aβ and αS. In this chapter, we introduce Aβ and αS in light of various hypotheses, and discuss different experimental and theoretical techniques that are used to study these two proteins along with their weaknesses and strengths. We suggest that a promising solution for studying Aβ and αS at the center of varying hypotheses could be provided by developing new techniques that link quantum mechanics, statistical mechanics, thermodynamics, bioinformatics to machine learning. Such new developments could also lead to development in experimental techniques.
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Affiliation(s)
- Orkid Coskuner
- Turkish-German University, Molecular Biotechnology, Istanbul, Turkey.
| | - Vladimir N Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States; Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences, Moscow, Russia.
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20
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Muller MP, Jiang T, Sun C, Lihan M, Pant S, Mahinthichaichan P, Trifan A, Tajkhorshid E. Characterization of Lipid-Protein Interactions and Lipid-Mediated Modulation of Membrane Protein Function through Molecular Simulation. Chem Rev 2019; 119:6086-6161. [PMID: 30978005 PMCID: PMC6506392 DOI: 10.1021/acs.chemrev.8b00608] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The cellular membrane constitutes one of the most fundamental compartments of a living cell, where key processes such as selective transport of material and exchange of information between the cell and its environment are mediated by proteins that are closely associated with the membrane. The heterogeneity of lipid composition of biological membranes and the effect of lipid molecules on the structure, dynamics, and function of membrane proteins are now widely recognized. Characterization of these functionally important lipid-protein interactions with experimental techniques is however still prohibitively challenging. Molecular dynamics (MD) simulations offer a powerful complementary approach with sufficient temporal and spatial resolutions to gain atomic-level structural information and energetics on lipid-protein interactions. In this review, we aim to provide a broad survey of MD simulations focusing on exploring lipid-protein interactions and characterizing lipid-modulated protein structure and dynamics that have been successful in providing novel insight into the mechanism of membrane protein function.
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Affiliation(s)
- Melanie P. Muller
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tao Jiang
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chang Sun
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Muyun Lihan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shashank Pant
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Paween Mahinthichaichan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Anda Trifan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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21
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Sahoo A, Matysiak S. Computational insights into lipid assisted peptide misfolding and aggregation in neurodegeneration. Phys Chem Chem Phys 2019; 21:22679-22694. [DOI: 10.1039/c9cp02765c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
An overview of recent advances in computational investigation of peptide–lipid interactions in neurodegeneration – Alzheimer's, Parkinson's and Huntington's disease.
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Affiliation(s)
- Abhilash Sahoo
- Biophysics Program
- Institute of Physical Science and Technology
- University of Maryland
- College Park
- USA
| | - Silvina Matysiak
- Biophysics Program
- Institute of Physical Science and Technology
- University of Maryland
- College Park
- USA
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22
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Press-Sandler O, Miller Y. Molecular mechanisms of membrane-associated amyloid aggregation: Computational perspective and challenges. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1889-1905. [DOI: 10.1016/j.bbamem.2018.03.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/07/2018] [Accepted: 03/12/2018] [Indexed: 01/02/2023]
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23
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Vermaas JV, Rempe SB, Tajkhorshid E. Electrostatic lock in the transport cycle of the multidrug resistance transporter EmrE. Proc Natl Acad Sci U S A 2018; 115:E7502-E7511. [PMID: 30026196 PMCID: PMC6094130 DOI: 10.1073/pnas.1722399115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
EmrE is a small, homodimeric membrane transporter that exploits the established electrochemical proton gradient across the Escherichia coli inner membrane to export toxic polyaromatic cations, prototypical of the wider small-multidrug resistance transporter family. While prior studies have established many fundamental aspects of the specificity and rate of substrate transport in EmrE, low resolution of available structures has hampered identification of the transport coupling mechanism. Here we present a complete, refined atomic structure of EmrE optimized against available cryo-electron microscopy (cryo-EM) data to delineate the critical interactions by which EmrE regulates its conformation during the transport process. With the model, we conduct molecular dynamics simulations of the transporter in explicit membranes to probe EmrE dynamics under different substrate loading and conformational states, representing different intermediates in the transport cycle. The refined model is stable under extended simulation. The water dynamics in simulation indicate that the hydrogen-bonding networks around a pair of solvent-exposed glutamate residues (E14) depend on the loading state of EmrE. One specific hydrogen bond from a tyrosine (Y60) on one monomer to a glutamate (E14) on the opposite monomer is especially critical, as it locks the protein conformation when the glutamate is deprotonated. The hydrogen bond provided by Y60 lowers the [Formula: see text] of one glutamate relative to the other, suggesting both glutamates should be protonated for the hydrogen bond to break and a substrate-free transition to take place. These findings establish the molecular mechanism for the coupling between proton transfer reactions and protein conformation in this proton-coupled secondary transporter.
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Affiliation(s)
- Josh V Vermaas
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Biological and Engineering Sciences Center, Sandia National Laboratories, Albuquerque, NM 87185
| | - Susan B Rempe
- Biological and Engineering Sciences Center, Sandia National Laboratories, Albuquerque, NM 87185
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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24
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Scheurer M, Rodenkirch P, Siggel M, Bernardi RC, Schulten K, Tajkhorshid E, Rudack T. PyContact: Rapid, Customizable, and Visual Analysis of Noncovalent Interactions in MD Simulations. Biophys J 2018; 114:577-583. [PMID: 29414703 PMCID: PMC5985026 DOI: 10.1016/j.bpj.2017.12.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/27/2017] [Accepted: 12/04/2017] [Indexed: 12/18/2022] Open
Abstract
Molecular dynamics (MD) simulations have become ubiquitous in all areas of life sciences. The size and model complexity of MD simulations are rapidly growing along with increasing computing power and improved algorithms. This growth has led to the production of a large amount of simulation data that need to be filtered for relevant information to address specific biomedical and biochemical questions. One of the most relevant molecular properties that can be investigated by all-atom MD simulations is the time-dependent evolution of the complex noncovalent interaction networks governing such fundamental aspects as molecular recognition, binding strength, and mechanical and structural stability. Extracting, evaluating, and visualizing noncovalent interactions is a key task in the daily work of structural biologists. We have developed PyContact, an easy-to-use, highly flexible, and intuitive graphical user interface-based application, designed to provide a toolkit to investigate biomolecular interactions in MD trajectories. PyContact is designed to facilitate this task by enabling identification of relevant noncovalent interactions in a comprehensible manner. The implementation of PyContact as a standalone application enables rapid analysis and data visualization without any additional programming requirements, and also preserves full in-program customization and extension capabilities for advanced users. The statistical analysis representation is interactively combined with full mapping of the results on the molecular system through the synergistic connection between PyContact and VMD. We showcase the capabilities and scientific significance of PyContact by analyzing and visualizing in great detail the noncovalent interactions underlying the ion permeation pathway of the human P2X3 receptor. As a second application, we examine the protein-protein interaction network of the mechanically ultrastable cohesin-dockering complex.
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Affiliation(s)
- Maximilian Scheurer
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Biochemistry Center, Heidelberg University, Heidelberg, Germany; Interdisciplinary Center for Scientific Computing, Heidelberg, Germany
| | | | - Marc Siggel
- Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - Rafael C Bernardi
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Klaus Schulten
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Department of Biochemistry, Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
| | - Till Rudack
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Department of Biophysics, Ruhr University Bochum, Bochum, Germany.
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25
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Hung HM, Hang TD, Nguyen MT. Molecular details of spontaneous insertion and interaction of HCV non-structure 3 protease protein domain with PIP2-containing membrane. Proteins 2018; 86:423-433. [PMID: 29341226 DOI: 10.1002/prot.25458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/02/2018] [Accepted: 01/11/2018] [Indexed: 12/16/2022]
Abstract
Hepatitis C virus (HCV), known as the leading cause of liver cirrhosis, viral hepatitis, and hepatocellular carcinoma, has been affecting more than 150 million people globally. The HCV non-structure 3 (NS3) protease protein domain plays a key role in HCV replication and pathogenesis; and is currently a primary target for HCV antiviral therapy. Through unbiased molecular dynamics simulations which take advantage of the novel highly mobile membrane mimetic model, we constructed the membrane-bound state of the protein domain at the atomic level. Our results indicated that protease domain of HCV NS3 protein can spontaneously bind and penetrate to an endoplasmic reticulum complex membrane containing phosphatidylinositol 4,5-bisphosphate (PIP2). An amphipathic helix α0 and loop S1 show their anchoring role to keep the protein on the membrane surface. Proper orientation of the protein domain at membrane surface was identified through measuring tilt angles of two specific vectors, wherein residue R161 plays a crucial role in its final orientation. Remarkably, PIP2 molecules were observed to bind to three main sites of the protease domain via specific electrostatic contacts and hydrogen bonds. PIP2-interaction determines the protein orientation at the membrane while both hydrophobic interplay and PIP2-interaction can stabilize the NS3 - membrane complex. Simulated results provide us with a detailed characterization of insertion, orientation and PIP2-interaction of NS3 protease domain at membrane environment, thus enhancing our understanding of structural functions and mechanism for the association of HCV non-structure 3 protein with respect to ER membranes.
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Affiliation(s)
- Huynh Minh Hung
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven, B-3001, Belgium.,Department of Chemistry, Quy Nhon University, Quy Nhon, Vietnam
| | - Tran Dieu Hang
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven, B-3001, Belgium.,Department of Chemistry, Quy Nhon University, Quy Nhon, Vietnam
| | - Minh Tho Nguyen
- Computational Chemistry Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam.,Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam.,Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven, B-3001, Belgium
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26
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Overk C, Rockenstein E, Valera E, Stefanova N, Wenning G, Masliah E. Multiple system atrophy: experimental models and reality. Acta Neuropathol 2018; 135:33-47. [PMID: 29058121 PMCID: PMC6156777 DOI: 10.1007/s00401-017-1772-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 09/29/2017] [Accepted: 09/29/2017] [Indexed: 01/08/2023]
Abstract
Multiple system atrophy (MSA) is a rapidly progressing fatal synucleinopathy of the aging population characterized by parkinsonism, dysautonomia, and in some cases ataxia. Unlike other synucleinopathies, in this disorder the synaptic protein, α-synuclein (α-syn), predominantly accumulates in oligodendroglial cells (and to some extent in neurons), leading to maturation defects of oligodendrocytes, demyelination, and neurodegeneration. The mechanisms through which α-syn deposits occur in oligodendrocytes and neurons in MSA are not completely clear. While some studies suggest that α-syn might transfer from neurons to glial cells, others propose that α-syn might be aberrantly overexpressed by oligodendroglial cells. A number of in vivo models have been developed, including transgenic mice overexpressing α-syn under oligodendroglial promoters (e.g.: MBP, PLP, and CNP). Other models have been recently developed either by injecting synthetic α-syn fibrils or brain homogenates from patients with MSA into wild-type mice or by using viral vectors expressing α-syn under the MBP promoter in rats and non-human primates. Each of these models reproduces some of the neuropathological and functional aspects of MSA; however, none of them fully replicate the spectrum of MSA. Understanding better the mechanisms of how α-syn accumulates in oligodendrocytes and neurons will help in developing better models that recapitulate various pathogenic aspects of MSA in combination with translatable biomarkers of early stages of the disease that are necessary to devise disease-modifying therapeutics for MSA.
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Affiliation(s)
- Cassia Overk
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093-0624, USA
| | - Edward Rockenstein
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093-0624, USA
| | - Elvira Valera
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093-0624, USA
| | - Nadia Stefanova
- Division of Clinical Neurobiology, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Gregor Wenning
- Division of Clinical Neurobiology, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Eliezer Masliah
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093-0624, USA.
- Molecular Neuropathology Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, 20892, USA.
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27
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Jamal S, Kumari A, Singh A, Goyal S, Grover A. Conformational Ensembles of α-Synuclein Derived Peptide with Different Osmolytes from Temperature Replica Exchange Sampling. Front Neurosci 2017; 11:684. [PMID: 29270108 PMCID: PMC5725442 DOI: 10.3389/fnins.2017.00684] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/22/2017] [Indexed: 11/13/2022] Open
Abstract
Intrinsically disordered proteins (IDP) are a class of proteins that do not have a stable three-dimensional structure and can adopt a range of conformations playing various vital functional role. Alpha-synuclein is one such IDP which can aggregate into toxic protofibrils and has been associated largely with Parkinson's disease (PD) along with other neurodegenerative diseases. Osmolytes are small organic compounds that can alter the environment around the proteins by acting as denaturants or protectants for the proteins. In the present study, we have conducted a series of replica exchange molecular dynamics simulations to explore the role of osmolytes, urea which is a denaturant and TMAO (trimethylamine N-oxide), a protecting osmolyte, in aggregation and conformations of the synuclein peptide. We observed that both the osmolytes have significantly distinct impacts on the peptide and led to transitions of the conformations of the peptide from one state to other. Our findings highlighted that urea attenuated peptide aggregation and resulted in the formation of extended peptide structures whereas TMAO led to compact and folded forms of the peptide.
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Affiliation(s)
- Salma Jamal
- Department of Bioscience and Biotechnology, Banasthali University, Tonk, India
| | - Anchala Kumari
- Department of Biotechnology, TERI School of Advanced Studies, New Delhi, India
| | - Aditi Singh
- Department of Biotechnology, TERI School of Advanced Studies, New Delhi, India
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Sukriti Goyal
- Department of Bioscience and Biotechnology, Banasthali University, Tonk, India
| | - Abhinav Grover
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
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28
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Tietjen GT, Baylon JL, Kerr D, Gong Z, Henderson JM, Heffern CTR, Meron M, Lin B, Schlossman ML, Adams EJ, Tajkhorshid E, Lee KYC. Coupling X-Ray Reflectivity and In Silico Binding to Yield Dynamics of Membrane Recognition by Tim1. Biophys J 2017; 113:1505-1519. [PMID: 28978444 DOI: 10.1016/j.bpj.2017.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 07/28/2017] [Accepted: 08/02/2017] [Indexed: 12/16/2022] Open
Abstract
The dynamic nature of lipid membranes presents significant challenges with respect to understanding the molecular basis of protein/membrane interactions. Consequently, there is relatively little known about the structural mechanisms by which membrane-binding proteins might distinguish subtle variations in lipid membrane composition and/or structure. We have previously developed a multidisciplinary approach that combines molecular dynamics simulation with interfacial x-ray scattering experiments to produce an atomistic model for phosphatidylserine recognition by the immune receptor Tim4. However, this approach requires a previously determined protein crystal structure in a membrane-bound conformation. Tim1, a Tim4 homolog with distinct differences in both immunological function and sensitivity to membrane composition, was crystalized in a closed-loop conformation that is unlikely to support membrane binding. Here we have used a previously described highly mobile membrane mimetic membrane in combination with a conventional lipid bilayer model to generate a membrane-bound configuration of Tim1 in silico. This refined structure provided a significantly improved fit of experimental x-ray reflectivity data. Moreover, the coupling of the x-ray reflectivity analysis with both highly mobile membrane mimetic membranes and conventional lipid bilayer molecular dynamics simulations yielded a dynamic model of phosphatidylserine membrane recognition by Tim1 with atomic-level detail. In addition to providing, to our knowledge, new insights into the molecular mechanisms that distinguish the various Tim receptors, these results demonstrate that in silico membrane-binding simulations can remove the requirement that the existing crystal structure be in the membrane-bound conformation for effective x-ray reflectivity analysis. Consequently, this refined methodology has the potential for much broader applicability with respect to defining the atomistic details of membrane-binding proteins.
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Affiliation(s)
- Gregory T Tietjen
- Program in Biophysical Sciences, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois
| | - Javier L Baylon
- Center for Biophysics and Quantitative Biology and Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois
| | - Daniel Kerr
- Program in Biophysical Sciences, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois
| | - Zhiliang Gong
- Department of Chemistry, The University of Chicago, Chicago, Illinois
| | | | | | - Mati Meron
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois
| | - Binhua Lin
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois; James Franck Institute, The University of Chicago, Chicago, Illinois
| | - Mark L Schlossman
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
| | - Erin J Adams
- Program in Biophysical Sciences, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois; Department of Biochemistry and Molecular Biology and Committee on Immunology, The University of Chicago, Chicago, Illinois
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology and Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois; College of Medicine and Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois.
| | - Ka Yee C Lee
- Program in Biophysical Sciences, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois; Department of Chemistry, The University of Chicago, Chicago, Illinois; James Franck Institute, The University of Chicago, Chicago, Illinois.
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29
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Bu B, Tong X, Li D, Hu Y, He W, Zhao C, Hu R, Li X, Shao Y, Liu C, Zhao Q, Ji B, Diao J. N-Terminal Acetylation Preserves α-Synuclein from Oligomerization by Blocking Intermolecular Hydrogen Bonds. ACS Chem Neurosci 2017; 8:2145-2151. [PMID: 28741930 DOI: 10.1021/acschemneuro.7b00250] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The abnormal aggregation of α-synuclein (α-Syn) is closely associated with Parkinson's disease. Different post-translational modifications of α-Syn have been identified and contribute distinctly in α-Syn aggregation and cytotoxicity. Recently, α-Syn was reported to be N-terminally acetylated in cells, yet the functional implication of this modification, especially in α-Syn oligomerization, remains unclear. By using a solid-state nanopore system, we found that N-terminal acetylation can significantly decrease α-Syn oligomerization. Replica-exchange molecular dynamics simulations further revealed that addition of an acetyl group at the N-terminus disrupts intermolecular hydrogen bonds, which slows down the initial α-Syn oligomerization. Our finding highlights the essential role of N-terminal acetylation of α-Syn in preserving its native conformation against pathological aggregation.
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Affiliation(s)
- Bing Bu
- Biomechanics
and Biomaterials Laboratory, Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081, China
| | - Xin Tong
- State
Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory,
School of Physics, Peking University, Beijing 100871, China
| | - Dechang Li
- Biomechanics
and Biomaterials Laboratory, Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081, China
| | - Yachong Hu
- Department
of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
- Key
Laboratory of Biomedical Information Engineering of the Ministry of
Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China
| | - Wangxiao He
- Key
Laboratory of Biomedical Information Engineering of the Ministry of
Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China
| | - Chunyu Zhao
- Interdisciplinary
Research Center on Biology and Chemistry, Shanghai Institute of Organic
Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Rui Hu
- State
Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory,
School of Physics, Peking University, Beijing 100871, China
| | - Xiaoqing Li
- State
Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory,
School of Physics, Peking University, Beijing 100871, China
| | - Yongping Shao
- Key
Laboratory of Biomedical Information Engineering of the Ministry of
Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China
| | - Cong Liu
- Interdisciplinary
Research Center on Biology and Chemistry, Shanghai Institute of Organic
Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Qing Zhao
- State
Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory,
School of Physics, Peking University, Beijing 100871, China
| | - Baohua Ji
- Biomechanics
and Biomaterials Laboratory, Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081, China
| | - Jiajie Diao
- Department
of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, United States
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30
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Muller MP, Wang Y, Morrissey JH, Tajkhorshid E. Lipid specificity of the membrane binding domain of coagulation factor X. J Thromb Haemost 2017; 15:2005-2016. [PMID: 28782177 PMCID: PMC5630516 DOI: 10.1111/jth.13788] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Indexed: 01/19/2023]
Abstract
Essentials Membrane-binding GLA domains of coagulation factors are essential for proper clot formation. Factor X (FX) is specific to phosphatidylserine (PS) lipids through unknown atomic-level interactions. Molecular dynamics simulations were used to develop the first membrane-bound model of FX-GLA. PS binding modes of FX-GLA were described, and potential PS-specific binding sites identified. SUMMARY Background Factor X (FX) binds to cell membranes in a highly phospholipid-dependent manner and, in complex with tissue factor and factor VIIa (FVIIa), initiates the clotting cascade. Experimental information concerning the membrane-bound structure of FX with atomic resolution has remained elusive because of the fluid nature of cellular membranes. FX is known to bind preferentially to phosphatidylserine (PS). Objectives To develop the first membrane-bound model of the FX-GLA domain to PS at atomic level, and to identify PS-specific binding sites of the FX-GLA domain. Methods Molecular dynamics (MD) simulations were performed to develop an atomic-level model for the FX-GLA domain bound to PS bilayers. We utilized a membrane representation with enhanced lipid mobility, termed the highly mobile membrane mimetic (HMMM), permitting spontaneous membrane binding and insertion by FX-GLA in multiple 100-ns simulations. In 14 independent simulations, FX-GLA bound spontaneously to the membrane. The resulting membrane-bound models were converted from HMMM to conventional membrane and simulated for an additional 100 ns. Results The final membrane-bound FX-GLA model allowed for detailed characterization of the orientation, insertion depth and lipid interactions of the domain, providing insight into the molecular basis of its PS specificity. All binding simulations converged to the same configuration despite differing initial orientations. Conclusions Analysis of interactions between residues in FX-GLA and lipid-charged groups allowed for potential PS-specific binding sites to be identified. This new structural and dynamic information provides an additional step towards a full understanding of the role of atomic-level lipid-protein interactions in regulating the critical and complex clotting cascade.
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Affiliation(s)
- Melanie P. Muller
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
| | - Yan Wang
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
| | - James H. Morrissey
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
| | - Emad Tajkhorshid
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
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31
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Christensen M, Skeby KK, Schiøtt B. Identification of Key Interactions in the Initial Self-Assembly of Amylin in a Membrane Environment. Biochemistry 2017; 56:4884-4894. [PMID: 28786287 DOI: 10.1021/acs.biochem.7b00344] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Islet amyloid polypeptide, also known as amylin, forms aggregates that reduce the amount of insulin-producing cells in patients with type II diabetes mellitus. Much remains unknown about the process of aggregation and cytotoxicity, but it is known that certain cell membrane components can alter the rate of aggregation. Using atomistic molecular dynamics simulations combined with the highly mobile membrane mimetic model incorporating enhanced sampling of lipid diffusion, we investigate interaction of amylin peptides with the membrane components as well as the self-assembly of amylin. Consistent with experimental evidence, we find that an initial membrane-bound α-helical state folds into stable β-sheet structures upon self-assembly. Our results suggest the following mechanism for the initial phase of amylin self-assembly. The peptides move around on the membrane with the positively charged N-terminus interacting with the negatively charged lipid headgroups. When the peptides start to interact, they partly unfold and break some of the contacts with the membrane. The initial interactions between the peptides are dominated by aromatic and hydrophobic interactions. Oligomers are formed showing both intra- and interpeptide β-sheets, initially with interactions mainly in the C-terminal domain of the peptides. Decreasing the pH to 5.5 is known to inhibit amyloid formation. At low pH, His18 is protonated, adding a fourth positive charge at the peptide. With His18 protonated, no oligomerization is observed in the simulations. The additional charge gives a strong midpoint anchoring of the peptides to negatively charged membrane components, and the peptides experience additional interpeptide repulsion, thereby preventing interactions.
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Affiliation(s)
- Mikkel Christensen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark.,Sino-Danish Center for Education and Research , Beijing, China
| | - Katrine K Skeby
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark
| | - Birgit Schiøtt
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark
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32
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Vermaas JV, Pogorelov TV, Tajkhorshid E. Extension of the Highly Mobile Membrane Mimetic to Transmembrane Systems through Customized in Silico Solvents. J Phys Chem B 2017; 121:3764-3776. [PMID: 28241729 PMCID: PMC5558153 DOI: 10.1021/acs.jpcb.6b11378] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanics of the protein-lipid interactions of transmembrane proteins are difficult to capture with conventional atomic molecular dynamics, due to the slow lateral diffusion of lipids restricting sampling to states near the initial membrane configuration. The highly mobile membrane mimetic (HMMM) model accelerates lipid dynamics by modeling the acyl tails nearest to the membrane center as a fluid organic solvent while maintaining an atomic description of the lipid headgroups and short acyl tails. The HMMM has been applied to many peripheral protein systems; however, the organic solvent used to date caused deformations in transmembrane proteins by intercalating into the protein and disrupting interactions between individual side chains. We ameliorate the effect of the solvent on transmembrane protein structure through the development of two new in silico Lennard-Jones solvents. The parameters for the new solvents were determined through an extensive parameter search in order to match the bulk properties of alkanes in a highly simplified model. Using these new solvents, we substantially improve the insertion free energy profiles of 10 protein side chain analogues across the entire bilayer. In addition, we reduce the intercalation of solvent into transmembrane systems, resulting in native-like transmembrane protein structures from five different topological classes within a HMMM bilayer. The parametrization of the solvents, in addition to their computed physical properties, is discussed. By combining high lipid lateral diffusion with intact transmembrane proteins, we foresee the developed solvents being useful to efficiently identify membrane composition inhomogeneities and lipid binding caused by the presence of membrane proteins.
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Affiliation(s)
- Josh V Vermaas
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Taras V Pogorelov
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Department of Chemistry, School of Chemical Sciences, National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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33
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Vermaas JV, Tajkhorshid E. Differential Membrane Binding Mechanics of Synaptotagmin Isoforms Observed in Atomic Detail. Biochemistry 2016; 56:281-293. [PMID: 27997124 DOI: 10.1021/acs.biochem.6b00468] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Synaptotagmin (Syt) is a membrane-associated protein involved in vesicle fusion through the SNARE complex that is found throughout the human body in 17 different isoforms. These isoforms have two membrane-binding C2 domains, which sense Ca2+ and thereby promote anionic membrane binding and lead to vesicle fusion. Through molecular dynamics simulations using the highly mobile membrane mimetic acclerated bilayer model, we have investigated how small protein sequence changes in the Ca2+-binding loops of the C2 domains may give rise to the experimentally determined difference in binding kinetics between Syt-1 and Syt-7 isoforms. Syt-7 C2 domains are found to form more close contacts with anionic phospholipid headgroups, particularly in loop 1, where an additional positive charge in Syt-7 draws the loop closer to the membrane and causes the anchoring residue F167 to insert deeper into the bilayer than the corresponding methionine in Syt-1 (M173). By performing additional replica exchange umbrella sampling calculations, we demonstrate that these additional contacts increase the energetic cost of unbinding the Syt-7 C2 domains from the bilayer, causing them to unbind more slowly than their counterparts in Syt-1.
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Affiliation(s)
- Josh V Vermaas
- Center for Biophysics and Quantitative Biology, Department of Biochemistry, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, Department of Biochemistry, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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34
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Qi Y, Cheng X, Lee J, Vermaas JV, Pogorelov TV, Tajkhorshid E, Park S, Klauda JB, Im W. CHARMM-GUI HMMM Builder for Membrane Simulations with the Highly Mobile Membrane-Mimetic Model. Biophys J 2016; 109:2012-22. [PMID: 26588561 DOI: 10.1016/j.bpj.2015.10.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/06/2015] [Accepted: 10/09/2015] [Indexed: 12/12/2022] Open
Abstract
Slow diffusion of the lipids in conventional all-atom simulations of membrane systems makes it difficult to sample large rearrangements of lipids and protein-lipid interactions. Recently, Tajkhorshid and co-workers developed the highly mobile membrane-mimetic (HMMM) model with accelerated lipid motion by replacing the lipid tails with small organic molecules. The HMMM model provides accelerated lipid diffusion by one to two orders of magnitude, and is particularly useful in studying membrane-protein associations. However, building an HMMM simulation system is not easy, as it requires sophisticated treatment of the lipid tails. In this study, we have developed CHARMM-GUI HMMM Builder (http://www.charmm-gui.org/input/hmmm) to provide users with ready-to-go input files for simulating HMMM membrane systems with/without proteins. Various lipid-only and protein-lipid systems are simulated to validate the qualities of the systems generated by HMMM Builder with focus on the basic properties and advantages of the HMMM model. HMMM Builder supports all lipid types available in CHARMM-GUI and also provides a module to convert back and forth between an HMMM membrane and a full-length membrane. We expect HMMM Builder to be a useful tool in studying membrane systems with enhanced lipid diffusion.
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Affiliation(s)
- Yifei Qi
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas
| | - Xi Cheng
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas
| | - Jumin Lee
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas
| | - Josh V Vermaas
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois; Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Taras V Pogorelov
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois; School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois; National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, Illinois; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Emad Tajkhorshid
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois; Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Soohyung Park
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering and the Biophysics Program, The University of Maryland, College Park, Maryland
| | - Wonpil Im
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas.
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Madsen JJ, Fristrup P, Peters GH. Theoretical Assessment of Fluorinated Phospholipids in the Design of Liposomal Drug-Delivery Systems. J Phys Chem B 2016; 120:9661-71. [DOI: 10.1021/acs.jpcb.6b07206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Jesper J. Madsen
- Department of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Peter Fristrup
- Department of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Günther H. Peters
- Department of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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36
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Baylon JL, Vermaas JV, Muller MP, Arcario MJ, Pogorelov TV, Tajkhorshid E. Atomic-level description of protein-lipid interactions using an accelerated membrane model. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1858:1573-83. [PMID: 26940626 PMCID: PMC4877275 DOI: 10.1016/j.bbamem.2016.02.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 02/19/2016] [Accepted: 02/20/2016] [Indexed: 01/03/2023]
Abstract
Peripheral membrane proteins are structurally diverse proteins that are involved in fundamental cellular processes. Their activity of these proteins is frequently modulated through their interaction with cellular membranes, and as a result techniques to study the interfacial interaction between peripheral proteins and the membrane are in high demand. Due to the fluid nature of the membrane and the reversibility of protein-membrane interactions, the experimental study of these systems remains a challenging task. Molecular dynamics simulations offer a suitable approach to study protein-lipid interactions; however, the slow dynamics of the lipids often prevents sufficient sampling of specific membrane-protein interactions in atomistic simulations. To increase lipid dynamics while preserving the atomistic detail of protein-lipid interactions, in the highly mobile membrane-mimetic (HMMM) model the membrane core is replaced by an organic solvent, while short-tailed lipids provide a nearly complete representation of natural lipids at the organic solvent/water interface. Here, we present a brief introduction and a summary of recent applications of the HMMM to study different membrane proteins, complementing the experimental characterization of the presented systems, and we offer a perspective of future applications of the HMMM to study other classes of membrane proteins. This article is part of a Special Issue entitled: Membrane proteins edited by J.C. Gumbart and Sergei Noskov.
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Affiliation(s)
- Javier L Baylon
- Center for Biophysics and Quantitative Biology; Beckman Institute for Advanced Science and Technology.
| | - Josh V Vermaas
- Center for Biophysics and Quantitative Biology; Beckman Institute for Advanced Science and Technology.
| | - Melanie P Muller
- Center for Biophysics and Quantitative Biology; Beckman Institute for Advanced Science and Technology; College of Medicine.
| | - Mark J Arcario
- Center for Biophysics and Quantitative Biology; Beckman Institute for Advanced Science and Technology; College of Medicine.
| | - Taras V Pogorelov
- Beckman Institute for Advanced Science and Technology; School of Chemical Sciences; Department of Chemistry; National Center for Supercomputing Applications.
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology; Beckman Institute for Advanced Science and Technology; College of Medicine; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
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37
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Skeby KK, Andersen OJ, Pogorelov TV, Tajkhorshid E, Schiøtt B. Conformational Dynamics of the Human Islet Amyloid Polypeptide in a Membrane Environment: Toward the Aggregation Prone Form. Biochemistry 2016; 55:2031-42. [PMID: 26953503 PMCID: PMC5733697 DOI: 10.1021/acs.biochem.5b00507] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human islet amyloid polypeptide (hIAPP) is a 37-residue peptide hormone, which upon misfolding changes from the physiologically active monomer into pathological amyloid fibril aggregates in the pancreas of type 2 diabetes mellitus patients. During this process, the insulin-producing pancreatic β-cells are damaged; however, the underlying mechanism of this mode of cytotoxicity remains elusive. It is known that anionic lipids accelerate amyloid fibril formation, implicating the importance of the cellular membrane in the process, and that a pH close to the level in the β-cell secretory granules (pH 5.5) inhibits amyloid fibril formation. Using all-atom molecular dynamics simulations, we have investigated the membrane-associated monomer state of α-helical hIAPP, analyzed specific interactions of hIAPP with a mixed anionic-zwitterionic lipid membrane and examined the influence of pH on the structure and dynamics of hIAPP and its interaction with the membrane. We find that hIAPP primarily interacts with the membrane by forming favorable interactions between anionic lipids and the positively charged residues in the N-terminal part of the peptide. Rationalizing experimental findings, the simulations show that the N-terminal part of the peptide interacts with the membrane in the lipid headgroup region. At neutral pH, the C-terminal part of the peptide, which contains the residues that initiate fibril formation, displays a highly dynamic, unfolded state, which interacts with the membrane significantly less than the N-terminal part. Such an unfolded form can be proposed to contribute to the acceleration of fibril formation. At low pH, protonation of His18 mediates a stronger interaction of the C-terminal part with the membrane, resulting in the immobilization of the C-terminal part on the membrane surface that might constitute a mechanism by which low pH inhibits fibril formation.
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Affiliation(s)
- Katrine Kirkeby Skeby
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO) and the Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus, Denmark
| | - Ole Juul Andersen
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO) and the Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus, Denmark
| | - Taras V. Pogorelov
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Birgit Schiøtt
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO) and the Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus, Denmark
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38
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Braun AR, Sachs JN. α-Synuclein Reduces Tension and Increases Undulations in Simulations of Small Unilamellar Vesicles. Biophys J 2016; 108:1848-51. [PMID: 25902424 DOI: 10.1016/j.bpj.2015.03.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/23/2015] [Accepted: 03/10/2015] [Indexed: 01/21/2023] Open
Abstract
Using coarse-grained molecular dynamics simulations we have explored the effect of α-Synuclein (αSyn) on the structural and mechanical properties of small unilamellar vesicles in the fluid-phase. The study is motivated by observations that a high density of membrane-bound αSyn inhibits the fusion of synthetic small unilamellar vesicles. By combining three-dimensional pressure tensor calculations with our recently developed spherical harmonics fluctuation analysis approach, we show a reduction in membrane surface tension and increased membrane undulations when αSyn is bound to the vesicle's outer leaflet at a 200:1 L/P. The protein effects these changes by decreasing the negative pressure in the headgroup region of the outer leaflet and increasing the positive pressure throughout the hydrocarbon core.
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Affiliation(s)
- Anthony R Braun
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Jonathan N Sachs
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota.
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39
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Synchrotron FTIR micro-spectroscopy for structural analysis of Lewy bodies in the brain of Parkinson's disease patients. Sci Rep 2015; 5:17625. [PMID: 26621077 PMCID: PMC4664933 DOI: 10.1038/srep17625] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 11/03/2015] [Indexed: 12/15/2022] Open
Abstract
Lewy bodies (LBs), which mainly consist of α-synuclein (α-syn), are neuropathological hallmarks of patients with Parkinson’s disease (PD). The fine structure of LBs is unknown, and LBs cannot be made artificially. Nevertheless, many studies have described fibrillisation using recombinant α-syn purified from E. coli. An extremely fundamental problem is whether the structure of LBs is the same as that of recombinant amyloid fibrils. Thus, we used synchrotron Fourier transform infrared micro-spectroscopy (FTIRM) to analyse the fine structure of LBs in the brain of PD patients. Our results showed a shift in the infrared spectrum that indicates abundance of a β-sheet-rich structure in LBs. Also, 2D infrared mapping of LBs revealed that the content of the β-sheet structure is higher in the halo than in the core, and the core contains a large amount of proteins and lipids.
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40
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McDougle DR, Baylon JL, Meling DD, Kambalyal A, Grinkova YV, Hammernik J, Tajkhorshid E, Das A. Incorporation of charged residues in the CYP2J2 F-G loop disrupts CYP2J2-lipid bilayer interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2460-2470. [PMID: 26232558 DOI: 10.1016/j.bbamem.2015.07.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 12/19/2022]
Abstract
CYP2J2 epoxygenase is an extrahepatic, membrane bound cytochrome P450 (CYP) that is primarily found in the heart and mediates endogenous fatty acid metabolism. CYP2J2 interacts with membranes through an N-terminal anchor and various non-contiguous hydrophobic residues. The molecular details of the motifs that mediate membrane interactions are complex and not fully understood. To gain better insights of these complex protein-lipid interactions, we employed molecular dynamics (MD) simulations using a highly mobile membrane mimetic (HMMM) model that enabled multiple independent spontaneous membrane binding events to be captured. Simulations revealed that CYP2J2 engages with the membrane at the F-G loop through hydrophobic residues Trp-235, Ille-236, and Phe-239. To explore the role of these residues, three F-G loop mutants were modeled from the truncated CYP2J2 construct (Δ34) which included Δ34-I236D, Δ34-F239H and Δ34-I236D/F239H. Using the HMMM coordinates of CYP2J2, the simulations were extended to a full POPC membrane which showed a significant decrease in the depth of insertion for each of the F-G loop mutants. The CYP2J2 F-G loop mutants were expressed in E. coli and were shown to be localized to the cytosolic fraction at a greater percentage relative to construct Δ34. Notably, the functional data demonstrated that the double mutant, Δ34-I236D/F239H, maintained native-like enzymatic activity. The membrane insertion characteristics were examined by monitoring CYP2J2 Trp-quenching fluorescence spectroscopy upon binding nanodiscs containing pyrene phospholipids. Relative to the Δ34 construct, the F-G loop mutants exhibited lower Trp quenching and membrane insertion. Taken together, the results suggest that the mutants exhibit a different membrane topology in agreement with the MD simulations and provide important evidence towards the involvement of key residues in the F-G loop of CYP2J2.
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Affiliation(s)
- Daniel R McDougle
- Department of Comparative Biosciences, University of Illinois Urbana-Champaign, Urbana IL 61801.,Medical Scholars Program, University of Illinois Urbana-Champaign, Urbana IL 61801
| | - Javier L Baylon
- Center for Biophysics and Computational Biology, University of Illinois Urbana-Champaign, Urbana IL 61801.,Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana IL 61801
| | - Daryl D Meling
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana IL 61801
| | - Amogh Kambalyal
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana IL 61801
| | - Yelena V Grinkova
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana IL 61801
| | - Jared Hammernik
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana IL 61801
| | - Emad Tajkhorshid
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana IL 61801.,Center for Biophysics and Computational Biology, University of Illinois Urbana-Champaign, Urbana IL 61801.,Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana IL 61801
| | - Aditi Das
- Department of Comparative Biosciences, University of Illinois Urbana-Champaign, Urbana IL 61801.,Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana IL 61801.,Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana IL 61801
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41
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Baylon JL, Tajkhorshid E. Capturing Spontaneous Membrane Insertion of the Influenza Virus Hemagglutinin Fusion Peptide. J Phys Chem B 2015; 119:7882-93. [PMID: 25996559 DOI: 10.1021/acs.jpcb.5b02135] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Hemagglutinin (HA) is a protein located on the surface of the influenza virus that mediates viral fusion to the host cellular membrane. During the fusion process the HA fusion peptide (HAfp), formed by the first 23 N-terminal residues of HA and structurally characterized by two alpha helices (Helix A and Helix B) tightly packed in a hairpin-like arrangement, is the only part of the virus in direct contact with the host membrane. After encountering the host cell, HAfp is believed to insert into the membrane, thereby initiating the fusion of the viral and host membranes. Detailed characterization of the interactions between the HAfp and cellular membrane is therefore of high relevance to the mechanism of viral entry into the host cell. Employing HMMM membrane representation with enhanced lipid mobility, we have performed a large set of independent simulations of unbiased membrane binding of HAfp. We have been able to capture spontaneous binding and insertion of HAfp consistently in nearly all the simulations. A reproducible membrane-bound configuration emerges from these simulations, despite employing a diverse set of initial configurations. Extension of several of the simulations into full membrane systems confirms the stability of the membrane-bound form obtained from HMMM binding simulations. The resulting model allows for the characterization of important interactions between the peptide and the membrane and the details of the binding process of the peptide for the first time. Upon membrane binding, Helix A inserts much deeper into the membrane than Helix B, suggesting that the former is responsible for hydrophobic anchoring of the peptide into the membrane. Helix B, in contrast, is found to establish major amphipathic interactions at the interfacial region thereby contributing to binding strength of HAfp.
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Affiliation(s)
- Javier L Baylon
- Center for Biophysics and Computational Biology, Department of Biochemistry, College of Medicine, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Center for Biophysics and Computational Biology, Department of Biochemistry, College of Medicine, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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42
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Vermaas JV, Baylon JL, Arcario MJ, Muller MP, Wu Z, Pogorelov TV, Tajkhorshid E. Efficient Exploration of Membrane-Associated Phenomena at Atomic Resolution. J Membr Biol 2015; 248:563-82. [PMID: 25998378 PMCID: PMC4490090 DOI: 10.1007/s00232-015-9806-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 04/30/2015] [Indexed: 12/24/2022]
Abstract
Biological membranes constitute a critical component in all living cells. In addition to providing a conducive environment to a wide range of cellular processes, including transport and signaling, mounting evidence has established active participation of specific lipids in modulating membrane protein function through various mechanisms. Understanding lipid-protein interactions underlying these mechanisms at a sufficiently high resolution has proven extremely challenging, partly due to the semi-fluid nature of the membrane. In order to address this challenge computationally, multiple methods have been developed, including an alternative membrane representation termed highly mobile membrane mimetic (HMMM) in which lateral lipid diffusion has been significantly enhanced without compromising atomic details. The model allows for efficient sampling of lipid-protein interactions at atomic resolution, thereby significantly enhancing the effectiveness of molecular dynamics simulations in capturing membrane-associated phenomena. In this review, after providing an overview of HMMM model development, we will describe briefly successful application of the model to study a variety of membrane processes, including lipid-dependent binding and insertion of peripheral proteins, the mechanism of phospholipid insertion into lipid bilayers, and characterization of optimal tilt angle of transmembrane helices. We conclude with practical recommendations for proper usage of the model in simulation studies of membrane processes.
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Affiliation(s)
- Josh V. Vermaas
- Beckman Institute, Department of Biochemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave. Urbana, IL 61801
| | - Javier L. Baylon
- Beckman Institute, Department of Biochemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave. Urbana, IL 61801
| | - Mark J. Arcario
- Beckman Institute, Department of Biochemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave. Urbana, IL 61801
| | - Melanie P. Muller
- Beckman Institute, Department of Biochemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave. Urbana, IL 61801
| | - Zhe Wu
- Beckman Institute, Department of Biochemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave. Urbana, IL 61801
| | - Taras V. Pogorelov
- Beckman Institute, Department of Biochemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave. Urbana, IL 61801
| | - Emad Tajkhorshid
- Beckman Institute, Department of Biochemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave. Urbana, IL 61801
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43
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Smaldone G, Diana D, Pollegioni L, Di Gaetano S, Fattorusso R, Pedone E. Insight into conformational modification of alpha-synuclein in the presence of neuronal whole cells and of their isolated membranes. FEBS Lett 2015; 589:798-804. [DOI: 10.1016/j.febslet.2015.02.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 01/30/2015] [Accepted: 02/10/2015] [Indexed: 10/24/2022]
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