1
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Wang B, Tieleman DP. The structure, self-assembly and dynamics of lipid nanodiscs revealed by computational approaches. Biophys Chem 2024; 309:107231. [PMID: 38569455 DOI: 10.1016/j.bpc.2024.107231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024]
Abstract
Nanodisc technology is increasingly being used in structural, biochemical and biophysical studies of membrane proteins. The computational approaches have revealed many important features of nanodisc assembly, structures and dynamics. Therefore, we reviewed the application of computational approaches, especially molecular modeling and molecular dyncamics (MD) simulations, to characterize nanodiscs, including the structural models, assembly and disassembly, protocols for modeling, structural properties and dynamics, and protein-lipid interactions in nanodiscs. More amazing computational studies about nanodiscs are looked forward to in the future.
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Affiliation(s)
- Beibei Wang
- Centre for Advanced Materials Research, Beijing Normal University, Zhuhai 519087, China.
| | - D Peter Tieleman
- Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary T2N 1N4, Canada.
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2
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Jeong C, Franklin R, Edler KJ, Vanommeslaeghe K, Krueger S, Curtis JE. Styrene-Maleic Acid Copolymer Nanodiscs to Determine the Shape of Membrane Proteins. J Phys Chem B 2022; 126:1034-1044. [PMID: 35089036 DOI: 10.1021/acs.jpcb.1c05050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lipid nanodiscs can be used to solubilize functional membrane proteins (MPs) in nativelike environments. Thus, they are promising reagents that have been proven useful to characterize MPs. Both protein and non-protein molecular belts have shown promise to maintain the structural integrity of MPs in lipid nanodiscs. Small-angle neutron scattering (SANS) can be used to determine low-resolution structures of proteins in solution, which can be enhanced through the use of contrast variation methods. We present theoretical contrast variation SANS results for protein and styrene-maleic acid copolymer (SMA) belt 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) nanodiscs with and without additional bound or transmembrane proteins. The predicted scattering properties are derived from atomistic molecular dynamics simulations to account for conformational fluctuations, and we determine deuterium-labeling conditions such that SANS intensity profiles only include contributions from the scattering of the MP of interest. We propose strategies to tune the neutron scattering length densities (SLDs) of the SMA and DMPC using selective deuterium labeling such that the SLD of the nanodisc becomes homogeneous and its scattering can essentially be eliminated in solvents containing an appropriate amount of D2O. These finely tuned labeled polymer-based nanodiscs are expected to be useful to extract the size and molecular shape information of MPs using SANS-based contrast variation experiments, and they can be used with MPs of any molecular weight.
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Affiliation(s)
- Cheol Jeong
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, Maryland 20899, United States.,Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, United States
| | - Ryan Franklin
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, Maryland 20899, United States
| | - Karen J Edler
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K
| | - Kenno Vanommeslaeghe
- Department of Analytical Chemistry, Applied Chemometrics and Molecular Modelling─FABI, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Susan Krueger
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, Maryland 20899, United States
| | - Joseph E Curtis
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, Maryland 20899, United States
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3
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Sligar SG, Denisov IG. Nanodiscs: A toolkit for membrane protein science. Protein Sci 2020; 30:297-315. [PMID: 33165998 DOI: 10.1002/pro.3994] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 10/30/2020] [Accepted: 10/30/2020] [Indexed: 12/25/2022]
Abstract
Membrane proteins are involved in numerous vital biological processes, including transport, signal transduction and the enzymes in a variety of metabolic pathways. Integral membrane proteins account for up to 30% of the human proteome and they make up more than half of all currently marketed therapeutic targets. Unfortunately, membrane proteins are inherently recalcitrant to study using the normal toolkit available to scientists, and one is most often left with the challenge of finding inhibitors, activators and specific antibodies using a denatured or detergent solubilized aggregate. The Nanodisc platform circumvents these challenges by providing a self-assembled system that renders typically insoluble, yet biologically and pharmacologically significant, targets such as receptors, transporters, enzymes, and viral antigens soluble in aqueous media in a native-like bilayer environment that maintain a target's functional activity. By providing a bilayer surface of defined composition and structure, Nanodiscs have found great utility in the study of cellular signaling complexes that assemble on a membrane surface. Nanodiscs provide a nanometer scale vehicle for the in vivo delivery of amphipathic drugs, therapeutic lipids, tethered nucleic acids, imaging agents and active protein complexes. This means for generating nanoscale lipid bilayers has spawned the successful use of numerous other polymer and peptide amphipathic systems. This review, in celebration of the Anfinsen Award, summarizes some recent results and provides an inroad into the current and historical literature.
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Affiliation(s)
- Stephen G Sligar
- Departments of Biochemistry Chemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA
| | - Ilia G Denisov
- Departments of Biochemistry Chemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA
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4
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McLean MA, Denisov IG, Grinkova YV, Sligar SG. Dark, Ultra-Dark and Ultra-Bright Nanodiscs for membrane protein investigations. Anal Biochem 2020; 607:113860. [PMID: 32750355 DOI: 10.1016/j.ab.2020.113860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/02/2020] [Accepted: 07/03/2020] [Indexed: 11/16/2022]
Abstract
We describe the construction, expression and purification of three new membrane scaffold proteins (MSP) for use in assembling Nanodiscs. These new MSPs have a variety of luminescent properties for use in combination with several analytical methods. "Dark" MSP has no tryptophan residues, "Ultra-Dark" replaces both tryptophan and tyrosine with non-fluorescent side chains, and "Ultra-Bright" adds additional tryptophans to the parent membrane scaffold protein to provide a dramatic increase in native tryptophan fluorescence. All MSPs were used to successfully assemble Nanodiscs nominally 10 nm in diameter, and the resultant bilayer structure was characterized. An example of the usefulness of these new scaffold proteins is provided.
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Affiliation(s)
- Mark A McLean
- Department of Biochemistry, University of Illinois, Urbana, IL, 16801, USA
| | - Ilia G Denisov
- Department of Biochemistry, University of Illinois, Urbana, IL, 16801, USA
| | - Yelena V Grinkova
- Department of Biochemistry, University of Illinois, Urbana, IL, 16801, USA
| | - Stephen G Sligar
- Department of Biochemistry, University of Illinois, Urbana, IL, 16801, USA; Department of Chemistry, University of Illinois, Urbana, IL, 16801, USA.
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5
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Bengtsen T, Holm VL, Kjølbye LR, Midtgaard SR, Johansen NT, Tesei G, Bottaro S, Schiøtt B, Arleth L, Lindorff-Larsen K. Structure and dynamics of a nanodisc by integrating NMR, SAXS and SANS experiments with molecular dynamics simulations. eLife 2020; 9:e56518. [PMID: 32729831 PMCID: PMC7426092 DOI: 10.7554/elife.56518] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 07/28/2020] [Indexed: 12/16/2022] Open
Abstract
Nanodiscs are membrane mimetics that consist of a protein belt surrounding a lipid bilayer, and are broadly used for characterization of membrane proteins. Here, we investigate the structure, dynamics and biophysical properties of two small nanodiscs, MSP1D1ΔH5 and ΔH4H5. We combine our SAXS and SANS experiments with molecular dynamics simulations and previously obtained NMR and EPR data to derive and validate a conformational ensemble that represents the structure and dynamics of the nanodisc. We find that it displays conformational heterogeneity with various elliptical shapes, and with substantial differences in lipid ordering in the centre and rim of the discs. Together, our results reconcile previous apparently conflicting observations about the shape of nanodiscs, and pave the way for future integrative studies of larger complex systems such as membrane proteins embedded in nanodiscs.
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Affiliation(s)
- Tone Bengtsen
- Structural Biology and NMR Laboratory and Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of CopenhagenCopenhagenDenmark
| | - Viktor L Holm
- Structural Biophysics, X-ray and Neutron Science, Niels Bohr Institute, University of CopenhagenCopenhagenDenmark
| | | | - Søren R Midtgaard
- Structural Biophysics, X-ray and Neutron Science, Niels Bohr Institute, University of CopenhagenCopenhagenDenmark
| | - Nicolai Tidemand Johansen
- Structural Biophysics, X-ray and Neutron Science, Niels Bohr Institute, University of CopenhagenCopenhagenDenmark
| | - Giulio Tesei
- Structural Biology and NMR Laboratory and Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of CopenhagenCopenhagenDenmark
| | - Sandro Bottaro
- Structural Biology and NMR Laboratory and Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of CopenhagenCopenhagenDenmark
| | | | - Lise Arleth
- Structural Biophysics, X-ray and Neutron Science, Niels Bohr Institute, University of CopenhagenCopenhagenDenmark
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory and Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of CopenhagenCopenhagenDenmark
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6
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Khalid S, Rouse SL. Simulation of subcellular structures. Curr Opin Struct Biol 2020; 61:167-172. [DOI: 10.1016/j.sbi.2019.12.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/18/2019] [Accepted: 12/26/2019] [Indexed: 12/21/2022]
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7
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Functional Reconstitution of HlyB, a Type I Secretion ABC Transporter, in Saposin-A Nanoparticles. Sci Rep 2019; 9:8436. [PMID: 31182729 PMCID: PMC6558041 DOI: 10.1038/s41598-019-44812-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 05/23/2019] [Indexed: 11/08/2022] Open
Abstract
Type I secretion systems (T1SS) are ubiquitous transport machineries in Gram-negative bacteria. They comprise a relatively simple assembly of three membrane-localised proteins: an inner-membrane complex composed of an ABC transporter and a membrane fusion protein, and a TolC-like outer membrane component. T1SS transport a wide variety of substrates with broad functional diversity. The ABC transporter hemolysin B (HlyB), for example, is part of the hemolysin A-T1SS in Escherichia coli. In contrast to canonical ABC transporters, an accessory domain, a C39 peptidase-like domain (CLD), is located at the N-terminus of HlyB and is essential for secretion. In this study, we have established an optimised purification protocol for HlyB and the subsequent reconstitution employing the saposin-nanoparticle system. We point out the negative influence of free detergent on the basal ATPase activity of HlyB, studied the influence of a lysolipid or lipid matrix on activity and present functional studies with the full-length substrate proHlyA in its folded and unfolded states, which both have a stimulatory effect on the ATPase activity.
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8
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Ray S, Holden S, Martin LL, Panwar AS. Mechanistic insight into the early stages of amyloid formation using an anuran peptide. Pept Sci (Hoboken) 2019. [DOI: 10.1002/pep2.24120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Sourav Ray
- IITB‐Monash Research AcademyIndian Institute of Technology Bombay Powai Mumbai India
- School of ChemistryMonash University Clayton Victoria Australia
- Department of Metallurgical Engineering and Materials ScienceIndian Institute of Technology Bombay Powai Mumbai India
| | | | | | - Ajay Singh Panwar
- Department of Metallurgical Engineering and Materials ScienceIndian Institute of Technology Bombay Powai Mumbai India
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9
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Qi Y, Lee J, Klauda JB, Im W. CHARMM-GUI Nanodisc Builder for modeling and simulation of various nanodisc systems. J Comput Chem 2019; 40:893-899. [PMID: 30677169 DOI: 10.1002/jcc.25773] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/05/2018] [Accepted: 12/11/2018] [Indexed: 01/13/2023]
Abstract
Nanodiscs are discoidal protein-lipid complexes that have wide applications in membrane protein studies. Modeling and simulation of nanodiscs are challenging due to the absence of structures of many membrane scaffold proteins (MSPs) that wrap around the membrane bilayer. We have developed CHARMM-GUI Nanodisc Builder (http://www.charmm-gui.org/input/nanodisc) to facilitate the setup of nanodisc simulation systems by modeling the MSPs with defined size and known structural features. A total of 11 different nanodiscs with a diameter from 80 to 180 Å are made available in both the all-atom CHARMM and two coarse-grained (PACE and Martini) force fields. The usage of the Nanodisc Builder is demonstrated with various simulation systems. The structures and dynamics of proteins and lipids in these systems were analyzed, showing similar behaviors to those from previous all-atom and coarse-grained nanodisc simulations. We expect the Nanodisc Builder to be a convenient and reliable tool for modeling and simulation of nanodisc systems. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Yifei Qi
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, China
| | - Jumin Lee
- Departments of Biological Sciences and Bioengineering, Lehigh University, Bethlehem, Pennsylvania
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering and the Biophysics Program, University of Maryland, College Park, Maryland
| | - Wonpil Im
- Departments of Biological Sciences and Bioengineering, Lehigh University, Bethlehem, Pennsylvania
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10
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Biswal D, Kusalik PG. Molecular simulations of self-assembly processes in metal-organic frameworks: Model dependence. J Chem Phys 2017; 147:044702. [PMID: 28764378 DOI: 10.1063/1.4994700] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Molecular simulation is a powerful tool for investigating microscopic behavior in various chemical systems, where the use of suitable models is critical to successfully reproduce the structural and dynamic properties of the real systems of interest. In this context, molecular dynamics simulation studies of self-assembly processes in metal-organic frameworks (MOFs), a well-known class of porous materials with interesting chemical and physical properties, are relatively challenging, where a reasonably accurate representation of metal-ligand interactions is anticipated to play an important role. In the current study, we both investigate the performance of some existing models and introduce and test new models to help explore the self-assembly in an archetypal Zn-carboxylate MOF system. To this end, the behavior of six different Zn-ion models, three solvent models, and two ligand models was examined and validated against key experimental structural parameters. To explore longer time scale ordering events during MOF self-assembly via explicit solvent simulations, it is necessary to identify a suitable combination of simplified model components representing metal ions, organic ligands, and solvent molecules. It was observed that an extended cationic dummy atom (ECDA) Zn-ion model combined with an all-atom carboxylate ligand model and a simple dipolar solvent model can reproduce characteristic experimental structures for the archetypal MOF system. The successful use of these models in extensive sets of molecular simulations, which provide key insights into the self-assembly mechanism of this archetypal MOF system occurring during the early stages of this process, has been very recently reported.
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Affiliation(s)
- Debasmita Biswal
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada
| | - Peter G Kusalik
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada
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11
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Abstract
Membrane proteins play a most important part in metabolism, signaling, cell motility, transport, development, and many other biochemical and biophysical processes which constitute fundamentals of life on the molecular level. Detailed understanding of these processes is necessary for the progress of life sciences and biomedical applications. Nanodiscs provide a new and powerful tool for a broad spectrum of biochemical and biophysical studies of membrane proteins and are commonly acknowledged as an optimal membrane mimetic system that provides control over size, composition, and specific functional modifications on the nanometer scale. In this review we attempted to combine a comprehensive list of various applications of nanodisc technology with systematic analysis of the most attractive features of this system and advantages provided by nanodiscs for structural and mechanistic studies of membrane proteins.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Stephen G Sligar
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
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12
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The power, pitfalls and potential of the nanodisc system for NMR-based studies. Biol Chem 2016; 397:1335-1354. [DOI: 10.1515/hsz-2016-0224] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 07/19/2016] [Indexed: 12/21/2022]
Abstract
Abstract
The choice of a suitable membrane mimicking environment is of fundamental importance for the characterization of structure and function of membrane proteins. In this respect, usage of the lipid bilayer nanodisc technology provides a unique potential for nuclear magnetic resonance (NMR)-based studies. This review summarizes the recent advances in this field, focusing on (i) the strengths of the system, (ii) the bottlenecks that may be faced, and (iii) promising capabilities that may be explored in future studies.
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13
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Jeřábek P, Florián J, Martínek V. Membrane-Anchored Cytochrome P450 1A2–Cytochrome b5 Complex Features an X-Shaped Contact between Antiparallel Transmembrane Helices. Chem Res Toxicol 2016; 29:626-36. [DOI: 10.1021/acs.chemrestox.5b00349] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Petr Jeřábek
- Department
of Biochemistry, Faculty of Science, Charles University in Prague, Albertov 2030, 128 43 Prague 2, Czech Republic
| | - Jan Florián
- Department
of Chemistry and Biochemistry, Loyola University Chicago, 1032 West Sheridan
Road, Chicago, Illinois 60660, United States
| | - Václav Martínek
- Department
of Biochemistry, Faculty of Science, Charles University in Prague, Albertov 2030, 128 43 Prague 2, Czech Republic
- Department of Teaching and Didactics of Chemistry, Faculty of Science, Charles University in Prague, Albertov 3, 128 43 Prague 2, Czech Republic
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14
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Pan L, Segrest JP. Computational studies of plasma lipoprotein lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2401-2420. [PMID: 26969087 DOI: 10.1016/j.bbamem.2016.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/03/2016] [Accepted: 03/04/2016] [Indexed: 12/27/2022]
Abstract
Plasma lipoproteins are macromolecular assemblies of proteins and lipids found in the blood. The lipid components of lipoproteins are amphipathic lipids such as phospholipids (PLs), and unesterified cholesterols (UCs) and hydrophobic lipids such as cholesteryl esters (CEs) and triglycerides (TGs). Since lipoproteins are soft matter supramolecular assemblies easily deformable by thermal fluctuations and they also exist in varying densities and protein/lipid components, a detailed understanding of their structure/function is experimentally difficult. Molecular dynamics (MD) simulation has emerged as a particularly promising way to explore the structure and dynamics of lipoproteins. The purpose of this review is to survey the current status of computational studies of the lipid components of the lipoproteins. Computational studies aim to explore three levels of complexity for the 3-dimensional structural dynamics of lipoproteins at various metabolic stages: (i) lipoprotein particles consist of protein with minimal lipid; (ii) lipoprotein particles consist of PL-rich discoidal bilayer-like lipid particles; (iii) mature circulating lipoprotein particles consist of CE-rich or TG-rich spheroidal lipid-droplet-like particles. Due to energy barriers involved in conversion between these species, other biomolecules also participate in lipoprotein biological assembly. For example: (i) lipid-poor apolipoprotein A-I (apoA-I) interacts with ATP-binding cassette transporter A1 (ABCA1) to produce nascent discoidal high density lipoprotein (dHDL) particles; (ii) lecithin-cholesterol acyltransferase (LCAT) mediates the conversion of UC to CE in dHDL, driving spheroidal HDL (sHDL) formation; (iii) transfer proteins, cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP), transfer both CE and TG and PL, respectively, between lipoprotein particles. Computational studies have the potential to explore different lipoprotein particles at each metabolic stage in atomistic detail. This review discusses the current status of computational methods including all-atom MD (AAMD), coarse-grain MD (CGMD), and MD-simulated annealing (MDSA) and their applications in lipoprotein structural dynamics and biological assemblies. Results from MD simulations are discussed and compared across studies in order to identify key findings, controversies, issues and future directions. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Lurong Pan
- Division of Gerontology, Geriatrics, & Palliative Care, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Jere P Segrest
- Division of Gerontology, Geriatrics, & Palliative Care, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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15
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Lee SC, Khalid S, Pollock NL, Knowles TJ, Edler K, Rothnie AJ, R T Thomas O, Dafforn TR. Encapsulated membrane proteins: A simplified system for molecular simulation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2549-2557. [PMID: 26946242 DOI: 10.1016/j.bbamem.2016.02.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 02/23/2016] [Accepted: 02/25/2016] [Indexed: 12/19/2022]
Abstract
Over the past 50years there has been considerable progress in our understanding of biomolecular interactions at an atomic level. This in turn has allowed molecular simulation methods employing full atomistic modelling at ever larger scales to develop. However, some challenging areas still remain where there is either a lack of atomic resolution structures or where the simulation system is inherently complex. An area where both challenges are present is that of membranes containing membrane proteins. In this review we analyse a new practical approach to membrane protein study that offers a potential new route to high resolution structures and the possibility to simplify simulations. These new approaches collectively recognise that preservation of the interaction between the membrane protein and the lipid bilayer is often essential to maintain structure and function. The new methods preserve these interactions by producing nano-scale disc shaped particles that include bilayer and the chosen protein. Currently two approaches lead in this area: the MSP system that relies on peptides to stabilise the discs, and SMALPs where an amphipathic styrene maleic acid copolymer is used. Both methods greatly enable protein production and hence have the potential to accelerate atomic resolution structure determination as well as providing a simplified format for simulations of membrane protein dynamics. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Sarah C Lee
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK
| | - Naomi L Pollock
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Tim J Knowles
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Karen Edler
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Alice J Rothnie
- School of Life & Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Owen R T Thomas
- School of Chemical Engineering, College of Engineering and Physical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Timothy R Dafforn
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
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16
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Gogonea V. Structural Insights into High Density Lipoprotein: Old Models and New Facts. Front Pharmacol 2016; 6:318. [PMID: 26793109 PMCID: PMC4709926 DOI: 10.3389/fphar.2015.00318] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 12/22/2015] [Indexed: 11/13/2022] Open
Abstract
The physiological link between circulating high density lipoprotein (HDL) levels and cardiovascular disease is well-documented, albeit its intricacies are not well-understood. An improved appreciation of HDL function and overall role in vascular health and disease requires at its foundation a better understanding of the lipoprotein's molecular structure, its formation, and its process of maturation through interactions with various plasma enzymes and cell receptors that intervene along the pathway of reverse cholesterol transport. This review focuses on summarizing recent developments in the field of lipid free apoA-I and HDL structure, with emphasis on new insights revealed by newly published nascent and spherical HDL models constructed by combining low resolution structures obtained from small angle neutron scattering (SANS) with contrast variation and geometrical constraints derived from hydrogen-deuterium exchange (HDX), crosslinking mass spectrometry, electron microscopy, Förster resonance energy transfer, and electron spin resonance. Recently published low resolution structures of nascent and spherical HDL obtained from SANS with contrast variation and isotopic labeling of apolipoprotein A-I (apoA-I) will be critically reviewed and discussed in terms of how they accommodate existing biophysical structural data from alternative approaches. The new low resolution structures revealed and also provided some answers to long standing questions concerning lipid organization and particle maturation of lipoproteins. The review will discuss the merits of newly proposed SANS based all atom models for nascent and spherical HDL, and compare them with accepted models. Finally, naturally occurring and bioengineered mutations in apoA-I, and their impact on HDL phenotype, are reviewed and discuss together with new therapeutics employed for restoring HDL function.
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Affiliation(s)
- Valentin Gogonea
- Department of Chemistry, Cleveland State UniversityCleveland, OH, USA; Departments of Cellular and Molecular Medicine and the Center for Cardiovascular Diagnostics and Prevention, Cleveland ClinicCleveland, OH, USA
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17
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Lyubartsev AP, Rabinovich AL. Force Field Development for Lipid Membrane Simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2483-2497. [PMID: 26766518 DOI: 10.1016/j.bbamem.2015.12.033] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 12/21/2015] [Accepted: 12/23/2015] [Indexed: 02/04/2023]
Abstract
With the rapid development of computer power and wide availability of modelling software computer simulations of realistic models of lipid membranes, including their interactions with various molecular species, polypeptides and membrane proteins have become feasible for many research groups. The crucial issue of the reliability of such simulations is the quality of the force field, and many efforts, especially in the latest several years, have been devoted to parametrization and optimization of the force fields for biomembrane modelling. In this review, we give account of the recent development in this area, covering different classes of force fields, principles of the force field parametrization, comparison of the force fields, and their experimental validation. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Alexander P Lyubartsev
- Department of Materials and Environmental Chemistry, Stockholm University, SE 106 91, Stockholm, Sweden.
| | - Alexander L Rabinovich
- Institute of Biology, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya 11, Petrozavodsk, 185910, Russian Federation.
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Vestergaard M, Kraft JF, Vosegaard T, Thøgersen L, Schiøtt B. Bicelles and Other Membrane Mimics: Comparison of Structure, Properties, and Dynamics from MD Simulations. J Phys Chem B 2015; 119:15831-43. [PMID: 26610232 DOI: 10.1021/acs.jpcb.5b08463] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The increased interest in studying membrane proteins has led to the development of new membrane mimics such as bicelles and nanodiscs. However, only limited knowledge is available of how these membrane mimics are affected by embedded proteins and how well they mimic a lipid bilayer. Herein, we present molecular dynamics simulations to elucidate structural and dynamic properties of small bicelles and compare them to a large alignable bicelle, a small nanodisc, and a lipid bilayer. Properties such as lipid packing and properties related to embedding both an α-helical peptide and a transmembrane protein are investigated. The small bicelles are found to be very dynamic and mainly assume a prolate shape substantiating that small bicelles cannot be regarded as well-defined disclike structures. However, addition of a peptide results in an increased tendency to form disc-shaped bicelles. The small bicelles and the nanodiscs show increased peptide solvation and difference in peptide orientation compared to embedding in a bilayer. The large bicelle imitated a bilayer well with respect to both curvature and peptide solvation, although peripheral binding of short tailed lipids to the embedded proteins is observed, which could hinder ligand binding or multimer formation.
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Affiliation(s)
- Mikkel Vestergaard
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Johan F Kraft
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Thomas Vosegaard
- Danish Center for Ultrahigh-Field NMR Spectroscopy and Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark
| | - Lea Thøgersen
- Center for Membrane Pumps in Cells and Disease (PUMPKIN), Bioinformatics Research Centre, Aarhus University , C.F. Møllers Alle 8, DK-8000 Aarhus C, Denmark
| | - Birgit Schiøtt
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus C, Denmark
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Han W, Wan CK, Wu YD. Toward a Coarse-Grained Protein Model Coupled with a Coarse-Grained Solvent Model: Solvation Free Energies of Amino Acid Side Chains. J Chem Theory Comput 2015; 4:1891-901. [PMID: 26620333 DOI: 10.1021/ct800184c] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Recently, we reported that molecular dynamics (MD) simulations using a coarse-grained (CG) peptide model coupled with a CG water model are able to reproduce many of the structural and thermodynamic features of short peptides with nonpolar side chains at 10(3) times the normal speed (JCTC, 2007, 3, 2146-2161). To further develop a CG protein model for MD simulations, we systematically parametrized the side chains of all 20 naturally occurring amino acids. We developed the parameters by fitting the dihedral potentials of 13 small molecules, the densities and self-solvation free energies of liquids of eight organic molecules, and the hydration free energies of 35 small organic molecules. In a set of 11 classes of compounds (105 in total) including alkanes, alcohols, ethers, ketones/aldehydes, amines, amides, aromatics, carboxylic acids, sulfides/thiols, alkyl ammoniums, and carboxylate ions, the average error in the calculated hydration free energies compared with experimental results is about 1.4 kJ/mol. The average error in the calculated transfer free energies of the 19 side-chain analogues of amino acids from cyclohexane to water is about 2.2 kJ/mol. These results are comparable to the results of all-atom models.
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Affiliation(s)
- Wei Han
- Department of Chemistry, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China, and National Laboratory of Molecular Sciences, College of Chemistry, Peking University, Beijing, China
| | - Cheuk-Kin Wan
- Department of Chemistry, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China, and National Laboratory of Molecular Sciences, College of Chemistry, Peking University, Beijing, China
| | - Yun-Dong Wu
- Department of Chemistry, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China, and National Laboratory of Molecular Sciences, College of Chemistry, Peking University, Beijing, China
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20
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Affiliation(s)
- Iwona Siuda
- Department of Biological
Sciences and Centre for Molecular Simulation, University of Calgary, 2500 University Drive North West, Calgary, Alberta T2N 1N4, Canada
| | - D. Peter Tieleman
- Department of Biological
Sciences and Centre for Molecular Simulation, University of Calgary, 2500 University Drive North West, Calgary, Alberta T2N 1N4, Canada
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21
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Debnath A, Schäfer LV. Structure and Dynamics of Phospholipid Nanodiscs from All-Atom and Coarse-Grained Simulations. J Phys Chem B 2015; 119:6991-7002. [PMID: 25978497 DOI: 10.1021/acs.jpcb.5b02101] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We investigated structural and dynamical properties of nanodiscs comprising dimyristoylphosphatidylcholine (DMPC) lipids and major scaffold protein MSP1Δ(1-22) from human apolipoprotein A-1 using combined all-atom and coarse-grained (CG) molecular dynamics (MD) simulations. The computational efficiency of the Martini-CG force field enables the spontaneous self-assembly of lipids and scaffold proteins into stable nanodisc structures on time scales up to tens of microseconds. Subsequent all-atom and CG-MD simulations reveal that the lipids in the nanodisc have lower configurational entropy and higher acyl tail order than in a lamellar bilayer phase. These altered average properties arise from rather differential behavior of lipids, depending on their location in the nanodisc. Since the scaffold proteins exert constrictive forces from the outer rim of the disc toward its center, lipids at the center of the nanodisc are highly ordered, whereas annular lipids that are in contact with the MSP proteins are remarkably disordered due to perturbed packing. Although specific differences between all-atom and CG simulations are also evident, the results obtained at both levels of resolution are in overall good agreement with each other and provide atomic level interpretations of recent experiments. Thus, the present study highlights the applicability of multiscale simulation approaches for nanodisc systems and opens the way for future applications, including the study of nanodisc-embedded membrane proteins.
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Affiliation(s)
- Ananya Debnath
- †Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur 342 011, India
| | - Lars V Schäfer
- ‡Lehrstuhl für Theoretische Chemie, Ruhr-University Bochum, D-44780 Bochum, Germany
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22
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Abstract
Membrane proteins are the gatekeepers to the cell and are essential to the function of all cells, controlling the flow of molecules and information across the cell membrane. Much effort has been put into the development of systems for studying membrane proteins in simplified environments that nevertheless mimic their native lipid environment. After isolation and production of purified membrane proteins in detergent, it is often necessary to reconstitute them into a lipid structure such as liposome, nanodisc, or lipodisq. Each of these has the advantage of returning the protein to a defined lipid environment, and the choice of system depends on the application. Regardless of the system to be used, the fundamental process involves the removal of detergent and incorporation of the protein into a stable lipid system. This chapter details methodologies we have developed, mainly focussed on the model G protein-coupled receptor (GPCR) neurotensin receptor 1, and the GPCR-homologue and model, bacteriorhopdopsin.
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Lin CY, Chao L. Tunable nucleation time of functional sphingomyelinase--lipid features studied by membrane array statistic tool. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:13008-17. [PMID: 24059643 DOI: 10.1021/la401826b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Aggregation or assembly of lipids and proteins could significantly change the proteins' function. A peripheral membrane enzyme, sphingomyelinase (SMase), has been reported to be able to assemble to a functional feature with its lipid substrate, sphingomyelin (SM), and its lipid product, ceramide (Cer). SMase seems to processes its substrate more effectively in this feature. Here, we report that the functional feature has a tunable formation time. The peculiar behavior is that the feature formation has a time lag depending on the membrane composition. We hypothesized that the time lag is due to the significant nucleation energy barrier when the feature phase forms in its metastable parent phase in the 2-D lipid membrane. To study the stochastic nucleation of the feature, we built a corralled lipid membrane platform with numerous isolated membrane systems in parallel to capture the nucleation statistics. Using the high-throughput approach and the appropriate experimental design to circumvent the interplay of the complicated phase segregation in membranes induced by SMase, we found that the nucleation rate of the feature can be tuned by the supersaturation of the enzyme, the lipid substrate, and the lipid product, in the fluid phase of the membrane. The correlation between the supersaturation and the nucleation rate can be well described by the classical nucleation theory equation, suggesting that the feature formation follows the nucleation process with a certain component ratio specified in the equation. The certain relative component ratio suggests that the feature may have certain organization instead of being random aggregation. In addition, our finding suggests that nucleation could serve as a time lag control mechanism in this enzymatic system, and ways to reduce nucleation energy barrier could be used to shorten the aggregation time lag and vice versa.
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Affiliation(s)
- Charng-Yu Lin
- Department of Chemical Engineering, National Taiwan University , Taipei 106, Taiwan
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24
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Rabinovich AL, Lyubartsev AP. Computer simulation of lipid membranes: Methodology and achievements. POLYMER SCIENCE SERIES C 2013. [DOI: 10.1134/s1811238213070060] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Miyazaki M, Tajima Y, Ishihama Y, Handa T, Nakano M. Effect of phospholipid composition on discoidal HDL formation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1340-6. [DOI: 10.1016/j.bbamem.2013.01.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Revised: 01/12/2013] [Accepted: 01/17/2013] [Indexed: 10/27/2022]
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Abstract
The time and length scales accessible by biomolecular simulations continue to increase. This is in part due to improvements in algorithms and computing performance, but is also the result of the emergence of coarse-grained (CG) potentials, which complement and extend the information obtainable from fully detailed models. CG methods have already proven successful for a range of applications that benefit from the ability to rapidly simulate spontaneous self-assembly within a lipid membrane environment, including the insertion and/or oligomerization of a range of "toy models," transmembrane peptides, and single- and multi-domain proteins. While these simplified approaches sacrifice atomistic level detail, it is now straightforward to "reverse map" from CG to atomistic descriptions, providing a strategy to assemble membrane proteins within a lipid environment, prior to all-atom simulation. Moreover, recent developments have been made in "dual resolution" techniques, allowing different molecules in the system to be modeled with atomistic or CG resolution simultaneously.
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Affiliation(s)
- Syma Khalid
- School of Chemistry, University of Southampton, Southampton, UK
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28
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Borhani DW, Shaw DE. The future of molecular dynamics simulations in drug discovery. J Comput Aided Mol Des 2011; 26:15-26. [PMID: 22183577 PMCID: PMC3268975 DOI: 10.1007/s10822-011-9517-y] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 12/05/2011] [Indexed: 02/06/2023]
Abstract
Molecular dynamics simulations can now track rapid processes—those occurring in less than about a millisecond—at atomic resolution for many biologically relevant systems. These simulations appear poised to exert a significant impact on how new drugs are found, perhaps even transforming the very process of drug discovery. We predict here future results we can expect from, and enhancements we need to make in, molecular dynamics simulations over the coming 25 years, and in so doing set out several Grand Challenges for the field. In the context of the problems now facing the pharmaceutical industry, we ask how we can best address drug discovery needs of the next quarter century using molecular dynamics simulations, and we suggest some possible approaches.
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Affiliation(s)
| | - David E. Shaw
- D. E. Shaw Research, New York, NY 10036 USA
- Center for Computational Biology and Bioinformatics, Columbia University, New York, NY 10032 USA
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Morgan CR, Hebling CM, Rand KD, Stafford DW, Jorgenson JW, Engen JR. Conformational transitions in the membrane scaffold protein of phospholipid bilayer nanodiscs. Mol Cell Proteomics 2011; 10:M111.010876. [PMID: 21715319 DOI: 10.1074/mcp.m111.010876] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Phospholipid bilayer nanodiscs are model membrane systems that provide an environment where membrane proteins are highly stable and monodisperse without the use of detergents or liposomes. Nanodiscs consist of a discoidal phospholipid bilayer encircled by two copies of an amphipathic alpha helical membrane scaffold protein, which is modeled from apolipoprotein A-1. Hydrogen exchange mass spectrometry was used to probe the structure and dynamics of the scaffold protein in the presence and absence of lipid. On nanodisc self-assembly, the entire scaffold protein gained significant protection from exchange, consistent with a large, protein-wide, structural rearrangement. This protection was short-lived and the scaffold protein was highly deuterated within 2 h. Several regions of the scaffold protein, in both the lipid-free and lipid-associated states, displayed EX1 unfolding kinetics. The rapid deuteration of the scaffold protein and the presence of correlated unfolding events both indicate that nanodiscs are dynamic rather than rigid bodies in solution. This work provides a catalog of the expected scaffold protein peptic peptides in a nanodisc-hydrogen exchange mass spectrometry experiment and their deuterium uptake signatures, data that can be used as a benchmark to verify correct assembly and nanodisc structure. Such reference data will be useful control data for all hydrogen exchange mass spectrometry experiments involving nanodiscs in which transmembrane or lipid-associated proteins are the primary molecule(s) of interest.
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Affiliation(s)
- Christopher R Morgan
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
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30
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Kim H, Hsin J, Liu Y, Selvin PR, Schulten K. Formation of salt bridges mediates internal dimerization of myosin VI medial tail domain. Structure 2011; 18:1443-9. [PMID: 21070943 DOI: 10.1016/j.str.2010.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 08/18/2010] [Accepted: 09/01/2010] [Indexed: 01/02/2023]
Abstract
The unconventional motor protein, myosin VI, is known to dimerize upon cargo binding to its C-terminal end. It has been shown that one of its tail domains, called the medial tail domain, is a dimerization region. The domain contains an unusual pattern of alternating charged residues and a few hydrophobic residues. To reveal the unknown dimerization mechanism of the medial tail domain, we employed molecular dynamics and single-molecule experimental techniques. Both techniques suggest that the formation of electrostatic-based interhelical salt bridges between oppositely charged residues is a key dimerization factor. For the dimerization to occur, the two identical helices within the dimer do not bind in a symmetric fashion, but rather with an offset of about one helical repeat. Calculations of the dimer-dissociation energy find the contribution of hydrophobic residues to the dimerization process to be minor; they also find that the asymmetric homodimer state is energetically favorable over a state of separate helices.
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Affiliation(s)
- Hyeongjun Kim
- Department of Physics and Center of the Physics of Living Cells, University of Illinois, Urbana, IL 61801, USA
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31
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Vuorela T, Catte A, Niemelä PS, Hall A, Hyvönen MT, Marrink SJ, Karttunen M, Vattulainen I. Role of lipids in spheroidal high density lipoproteins. PLoS Comput Biol 2010; 6:e1000964. [PMID: 21060857 PMCID: PMC2965744 DOI: 10.1371/journal.pcbi.1000964] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Accepted: 09/17/2010] [Indexed: 01/25/2023] Open
Abstract
We study the structure and dynamics of spherical high density lipoprotein (HDL) particles through coarse-grained multi-microsecond molecular dynamics simulations. We simulate both a lipid droplet without the apolipoprotein A-I (apoA-I) and the full HDL particle including two apoA-I molecules surrounding the lipid compartment. The present models are the first ones among computational studies where the size and lipid composition of HDL are realistic, corresponding to human serum HDL. We focus on the role of lipids in HDL structure and dynamics. Particular attention is paid to the assembly of lipids and the influence of lipid-protein interactions on HDL properties. We find that the properties of lipids depend significantly on their location in the particle (core, intermediate region, surface). Unlike the hydrophobic core, the intermediate and surface regions are characterized by prominent conformational lipid order. Yet, not only the conformations but also the dynamics of lipids are found to be distinctly different in the different regions of HDL, highlighting the importance of dynamics in considering the functionalization of HDL. The structure of the lipid droplet close to the HDL-water interface is altered by the presence of apoA-Is, with most prominent changes being observed for cholesterol and polar lipids. For cholesterol, slow trafficking between the surface layer and the regimes underneath is observed. The lipid-protein interactions are strongest for cholesterol, in particular its interaction with hydrophobic residues of apoA-I. Our results reveal that not only hydrophobicity but also conformational entropy of the molecules are the driving forces in the formation of HDL structure. The results provide the first detailed structural model for HDL and its dynamics with and without apoA-I, and indicate how the interplay and competition between entropy and detailed interactions may be used in nanoparticle and drug design through self-assembly.
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Affiliation(s)
- Timo Vuorela
- Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Andrea Catte
- Department of Physics, Tampere University of Technology, Tampere, Finland
- Department of Medicine and Center for Computational and Structural Biology, University of Alabama, Birmingham, Alabama, United States of America
| | | | - Anette Hall
- Department of Physics, Tampere University of Technology, Tampere, Finland
| | | | - Siewert-Jan Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Mikko Karttunen
- Department of Applied Mathematics, The University of Western Ontario, London, Ontario, Canada
| | - Ilpo Vattulainen
- Department of Physics, Tampere University of Technology, Tampere, Finland
- Department of Applied Physics, Aalto University School of Science and Technology, Espoo, Finland
- MEMPHYS–Center of Biomembrane Physics, Physics Department, University of Southern Denmark, Odense M, Denmark
- * E-mail:
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32
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Hebling CM, Morgan CR, Stafford DW, Jorgenson JW, Rand KD, Engen JR. Conformational analysis of membrane proteins in phospholipid bilayer nanodiscs by hydrogen exchange mass spectrometry. Anal Chem 2010; 82:5415-9. [PMID: 20518534 DOI: 10.1021/ac100962c] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The study of membrane protein structure and enzymology has traditionally been hampered by the inherent insolubility of membrane proteins in aqueous environments and experimental challenges in emulating an in vivo lipid environment. Phospholipid bilayer nanodiscs have recently been shown to be of great use for the study of membrane proteins since they offer a controllable, stable, and monodisperse model membrane with a nativelike lipid bilayer. Here we report the integration of nanodiscs with hydrogen exchange (HX) mass spectrometry (MS) experiments, thereby allowing for analysis of the native conformation of membrane proteins. gamma-Glutamyl carboxylase (GGCX), an approximately 94 kDa transmembrane protein, was inserted into nanodiscs and labeled with deuterium oxide under native conditions. Analytical parameters including sample-handling and chromatographic separation were optimized to measure the incorporation of deuterium into GGCX. Coupling nanodisc technology with HX MS offers an effective approach for investigating the conformation and dynamics of membrane proteins in their native environment and is therefore capable of providing much needed insight into the function of membrane proteins.
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Affiliation(s)
- Christine M Hebling
- Department of Chemistry, Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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33
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Gogonea V, Wu Z, Lee X, Pipich V, Li XM, Ioffe AI, Didonato JA, Hazen SL. Congruency between biophysical data from multiple platforms and molecular dynamics simulation of the double-super helix model of nascent high-density lipoprotein. Biochemistry 2010; 49:7323-43. [PMID: 20687589 DOI: 10.1021/bi100588a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The predicted structure and molecular trajectories from >80 ns molecular dynamics simulation of the solvated Double-Super Helix (DSH) model of nascent high-density lipoprotein (HDL) were determined and compared with experimental data on reconstituted nascent HDL obtained from multiple biophysical platforms, including small angle neutron scattering (SANS) with contrast variation, hydrogen-deuterium exchange tandem mass spectrometry (H/D-MS/MS), nuclear magnetic resonance spectroscopy (NMR), cross-linking tandem mass spectrometry (MS/MS), fluorescence resonance energy transfer (FRET), electron spin resonance spectroscopy (ESR), and electron microscopy. In general, biophysical constraints experimentally derived from the multiple platforms agree with the same quantities evaluated using the simulation trajectory. Notably, key structural features postulated for the recent DSH model of nascent HDL are retained during the simulation, including (1) the superhelical conformation of the antiparallel apolipoprotein A1 (apoA1) chains, (2) the lipid micellar-pseudolamellar organization, and (3) the solvent-exposed Solar Flare loops, proposed sites of interaction with LCAT (lecithin cholesteryl acyltransferase). Analysis of salt bridge persistence during simulation provides insights into structural features of apoA1 that forms the backbone of the lipoprotein. The combination of molecular dynamics simulation and experimental data from a broad range of biophysical platforms serves as a powerful approach to studying large macromolecular assemblies such as lipoproteins. This application to nascent HDL validates the DSH model proposed earlier and suggests new structural details of nascent HDL.
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Affiliation(s)
- Valentin Gogonea
- Department of Chemistry, Cleveland State University, Cleveland, Ohio 44115, USA.
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34
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Grinkova YV, Denisov IG, Sligar SG. Engineering extended membrane scaffold proteins for self-assembly of soluble nanoscale lipid bilayers. Protein Eng Des Sel 2010; 23:843-8. [PMID: 20817758 DOI: 10.1093/protein/gzq060] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
High-density lipoproteins (HDLs) play an important role in human health through the metabolism and trafficking of cholesterol as well as providing the feedstocks for steroid hormone biosynthesis. These particles contain proteins, primarily Apo-AI and phospholipid and progress through various structural forms including 'lipid-poor', 'discoidal' and 'spherical' entities as cholesterol esters and lipid are incorporated. The discoidal form of HDL is stabilized in solution by two encircling belts of Apo-AI. Previous protein engineering of the Apo-AI sequence has led to a series of amphipathic helical proteins, termed membrane scaffold proteins (MSPs), which have shown great value in assembling nanoscale soluble membrane bilayers, termed Nanodiscs, of homogeneous size and composition and in the assembly of numerous integral membrane proteins for biophysical and biochemical investigations. In this communication we document a protein engineering approach to generate and optimize an extended polypeptide MSP, which will self-assemble phospholipids into larger Nanodiscs with diameters of 16-17 nm. We extensively characterize these structures by size exclusion chromatography and solution X-ray scattering.
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Affiliation(s)
- Yelena V Grinkova
- School of Molecular and Cellular Biology, University of Illinois, 505 S. Goodwin Avenue, Urbana, IL 61801, USA
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35
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Bhat S, Sorci-Thomas MG, Calabresi L, Samuel MP, Thomas MJ. Conformation of dimeric apolipoprotein A-I milano on recombinant lipoprotein particles. Biochemistry 2010; 49:5213-24. [PMID: 20524691 DOI: 10.1021/bi1003734] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Apolipoprotein A-I Milano (apoA-I(Milano)) is a naturally occurring human mutation of wild-type apolipoprotein A-I (apoA-I(WT)) having cystine substituted for arginine(173). Two molecules of apo-I(WT) form disks with phospholipid having a defined relationship between the apoA-I(WT) molecules. ApoA-I(Milano) forms cystine homodimers that would not allow the protein to adopt the conformation reported for apoA-I(WT). The conformational constraints for dimeric apoA-I(Milano) recombinant high-density lipoprotein (rHDL) disks made with phospholipid were deduced from a combination of chemical cross-linking and mass spectrometry. Lysine-selective homobifunctional cross-linkers were reacted with homogeneous rHDL having diameters of 78 and 125 A. After reduction, cross-linked apoA-I(Milano) was separated from monomeric apoprotein by gel electrophoresis and then subjected to in-gel trypsin digest. Cross-linked peptides were confirmed by MS/MS sequencing. The cross-links provided distance constraints that were used to refine models of lipid-bound dimeric apoA-I(Milano). These studies suggest that a single dimeric apoA-I(Milano) on 78 A diameter rHDL girdles the edge of a phospholipid disk assuming a "belt" conformation similar to the "belt" region of apoA-I(WT) on rHDL. However, the C-terminal end of dimeric apoA-I(Milano) wraps around the periphery of the particle to shield the fatty acid chains from water rather than folding back onto the "belt" as does apoA-I(WT). The two apoA-I(Milano) dimers on a 125 A diameter rHDL do not encircle the periphery of a phospholipid disk but appear to reside on the surface of a laminar micelle.
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Affiliation(s)
- Shaila Bhat
- Department of Pathology, Center for Lipid Science, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA
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36
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DeMille RC, Molinero V. Coarse-grained ions without charges: reproducing the solvation structure of NaCl in water using short-ranged potentials. J Chem Phys 2009; 131:034107. [PMID: 19624181 DOI: 10.1063/1.3170982] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A coarse-grained model of NaCl in water is presented where the ions are modeled without charge to avoid computationally challenging electrostatics. A monatomic model of water [V. Molinero and E. B. Moore, J. Phys. Chem. B 113, 4008 (2009)] is used as the basis for this coarse-grain approach. The ability of Na(+) to disrupt the native tetrahedral arrangement of water molecules, and of Cl(-) to integrate within this organization, is preserved in this mW-ion model through parametrization focused on water's solvation of these ions. This model successfully reproduces the structural effect of ions on water, referenced to observations from experiments and atomistic molecular dynamics simulations, while using extremely short-ranged potentials. Without Coulomb interactions the model replicates details of the ion-water structure such as distinguishing contact and solvent-separated ion pairs and the free energy barriers between them. The approach of mimicking ionic effects with short-ranged interactions results in performance gains of two orders of magnitude compared to Ewald methods. Explored over a broad range of salt concentration, the model reproduces the solvation structure and trends of diffusion relative to atomistic simulations and experimental results. The functional form of the mW-ion model can be parametrized to represent other electrolytes. With increased computational efficiency and reliable structural fidelity, this model promises to be an asset for accessing significantly longer simulation time scales with an explicit solvent in a coarse-grained system involving, for example, polyelectrolytes such as proteins, nucleic acids, and fuel-cell membranes.
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Affiliation(s)
- Robert C DeMille
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA
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Bayburt TH, Sligar SG. Membrane protein assembly into Nanodiscs. FEBS Lett 2009; 584:1721-7. [PMID: 19836392 DOI: 10.1016/j.febslet.2009.10.024] [Citation(s) in RCA: 557] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 10/09/2009] [Indexed: 01/25/2023]
Abstract
Nanodiscs are soluble nanoscale phospholipid bilayers which can self-assemble integral membrane proteins for biophysical, enzymatic or structural investigations. This means for rendering membrane proteins soluble at the single molecule level offers advantages over liposomes or detergent micelles in terms of size, stability, ability to add genetically modifiable features to the Nanodisc structure and ready access to both sides of the phospholipid bilayer domain. Thus the Nanodisc system provides a novel platform for understanding membrane protein function. We provide an overview of the Nanodisc approach and document through several examples many of the applications to the study of the structure and function of integral membrane proteins.
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Affiliation(s)
- Timothy H Bayburt
- Department of Biochemistry, School of Molecular and Cellular Biology, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA
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38
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Wu Z, Gogonea V, Lee X, Wagner MA, Li XM, Huang Y, Undurti A, May RP, Haertlein M, Moulin M, Gutsche I, Zaccai G, DiDonato JA, Hazen SL. Double superhelix model of high density lipoprotein. J Biol Chem 2009; 284:36605-36619. [PMID: 19812036 DOI: 10.1074/jbc.m109.039537] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
High density lipoprotein (HDL), the carrier of so-called "good" cholesterol, serves as the major athero-protective lipoprotein and has emerged as a key therapeutic target for cardiovascular disease. We applied small angle neutron scattering (SANS) with contrast variation and selective isotopic deuteration to the study of nascent HDL to obtain the low resolution structure in solution of the overall time-averaged conformation of apolipoprotein AI (apoA-I) versus the lipid (acyl chain) core of the particle. Remarkably, apoA-I is observed to possess an open helical shape that wraps around a central ellipsoidal lipid phase. Using the low resolution SANS shapes of the protein and lipid core as scaffolding, an all-atom computational model for the protein and lipid components of nascent HDL was developed by integrating complementary structural data from hydrogen/deuterium exchange mass spectrometry and previously published constraints from multiple biophysical techniques. Both SANS data and the new computational model, the double superhelix model, suggest an unexpected structural arrangement of protein and lipids of nascent HDL, an anti-parallel double superhelix wrapped around an ellipsoidal lipid phase. The protein and lipid organization in nascent HDL envisages a potential generalized mechanism for lipoprotein biogenesis and remodeling, biological processes critical to sterol and lipid transport, organismal energy metabolism, and innate immunity.
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Affiliation(s)
- Zhiping Wu
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Valentin Gogonea
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Department of Chemistry, Cleveland State University, Cleveland, Ohio 44115
| | - Xavier Lee
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Matthew A Wagner
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Xin-Min Li
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Ying Huang
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Arundhati Undurti
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Roland P May
- Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - Michael Haertlein
- Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - Martine Moulin
- Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - Irina Gutsche
- Unit of Virus-Host Interaction, Unité Mixte de Recherche 5233 Université Joseph Fourier-European Molecular Biology Laboratory-CNRS, 6 Rue Jules Horowitz, BP 181, 38042 Grenoble Cedex 9, France
| | - Giuseppe Zaccai
- Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France; Institut de Biologie Structurale, Commissariat à l'Energie Atomique-CNRS-Université Joseph Fourier, 38027 Grenoble, France
| | - Joseph A DiDonato
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195
| | - Stanley L Hazen
- Department of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195; Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, Ohio 44195; Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio 44195.
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39
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Simulations of membrane tubulation by lattices of amphiphysin N-BAR domains. Structure 2009; 17:882-92. [PMID: 19523905 DOI: 10.1016/j.str.2009.03.016] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 03/02/2009] [Accepted: 03/22/2009] [Indexed: 11/21/2022]
Abstract
Membrane compartments of manifold shapes are found in cells, often sculpted by cellular proteins. In particular, proteins of the BAR domain superfamily participate in membrane-sculpting processes in vivo and reshape also in vitro low-curvature membrane liposomes into high-curvature tubes and vesicles. Here we show by means of computer simulations totaling over 1 millisecond, how lattices involving parallel rows of amphiphysin N-BAR domains sculpt flat membranes into tubes. A highly detailed, dynamic picture of the 100-microsecond formation of membrane tubes by lattices of N-BAR domains is obtained. Lattice types inducing a wide range of membrane curvatures, with radii approximately 15-100 nm, are explored. The results suggest that multiple lattice types are viable for efficient membrane bending.
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40
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Miyazaki M, Nakano M, Fukuda M, Handa T. Smaller Discoidal High-Density Lipoprotein Particles Form Saddle Surfaces, but Not Planar Bilayers. Biochemistry 2009; 48:7756-63. [DOI: 10.1021/bi900785x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Masakazu Miyazaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Minoru Nakano
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masakazu Fukuda
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tetsurou Handa
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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Abstract
Human high-density lipoproteins (HDLs) are involved in the transport of cholesterol. The mechanism by which HDL assembles and functions is not well understood owing to a lack of structural information on circulating spherical HDL. Here, we report a series of molecular dynamics simulations that describe the maturation of discoidal HDL into spherical HDL upon incorporation of cholesterol ester as well as the resulting atomic level structure of a mature circulating spherical HDL particle. Sixty cholesterol ester molecules were added in a stepwise fashion to a discoidal HDL particle containing two apolipoproteins wrapped around a 160 dipalmitoylphosphatidylcholine lipid bilayer. The resulting matured particle, captured in a coarse-grained description, was then described in a consistent all-atom representation and analysed in chemical detail. The simulations show that maturation results from the formation of a highly dynamic hydrophobic core comprised of cholesterol ester surrounded by phospholipid and protein; the two apolipoprotein strands remain in a belt-like conformation as seen in the discoidal HDL particle, but with flexible N- and C-terminal helices and a central region stabilized by salt bridges. In the otherwise flexible lipoproteins, a less mobile central region provides an ideal location to bind lecithin cholesterol acyltransferase, the key enzyme that converts cholesterol to cholesterol ester during HDL maturation.
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Affiliation(s)
- Amy Y Shih
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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42
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Miao L, Schulten K. Transport-related structures and processes of the nuclear pore complex studied through molecular dynamics. Structure 2009; 17:449-59. [PMID: 19278659 DOI: 10.1016/j.str.2008.12.021] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 12/09/2008] [Accepted: 12/21/2008] [Indexed: 02/07/2023]
Abstract
Nuclear pore complexes (NPCs) are selectively gated pathways between nucleoplasm and cytoplasm. Whereas small molecules can diffuse freely through NPCs, large molecules (>40 kD) can pass only when bound to transport receptors. The NPC central channel is filled with disordered proteins, rich in phenylalanine-glycine (FG) repeats, referred to as FG-nups. Our simulations, carried out at coarse-grained and all-atom levels, show that arrays of FG-nups tethered to a planar surface, at an FG-repeat density found in the NPC, form dynamic brush-like structures of multiprotein bundles, whereas individual FG-nups form dynamic globular structures. More than half of the FG-repeats are found on the surface of the bundles, offering a favorable environment for transport receptors. Binding to FG-repeats and a sliding motion of NTF2 induced by binding and unbinding to phenylalanines were observed when adding this transport receptor into one of the brush-like structures.
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Affiliation(s)
- Lingling Miao
- Beckman Institute for Advanced Science and Technology and Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Affiliation(s)
- Stefan Balaz
- Department of Pharmaceutical Sciences, College of Pharmacy, North Dakota State University, Fargo, North Dakota 58105, USA.
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44
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Ordering effects of cholesterol and its analogues. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:97-121. [DOI: 10.1016/j.bbamem.2008.08.022] [Citation(s) in RCA: 450] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 08/27/2008] [Accepted: 08/31/2008] [Indexed: 12/12/2022]
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Vinchurkar MS, Bricarello DA, Lagerstedt JO, Buban JP, Stahlberg H, Oda MN, Voss JC, Parikh AN. Bridging Across Length Scales: Multi-Scale Ordering of Supported Lipid Bilayers via Lipoprotein Self-assembly and Surface Patterning. J Am Chem Soc 2008; 130:11164-9. [DOI: 10.1021/ja803110v] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Madhuri S. Vinchurkar
- Departments of Applied Science, Biochemistry & Molecular Medicine, Molecular and Cellular Biology, University of California, Davis, California 95616, and Lipid Biology in Health and Disease Research Group, Oakland Research Institute, Oakland, California 94609
| | - Daniel A. Bricarello
- Departments of Applied Science, Biochemistry & Molecular Medicine, Molecular and Cellular Biology, University of California, Davis, California 95616, and Lipid Biology in Health and Disease Research Group, Oakland Research Institute, Oakland, California 94609
| | - Jens O. Lagerstedt
- Departments of Applied Science, Biochemistry & Molecular Medicine, Molecular and Cellular Biology, University of California, Davis, California 95616, and Lipid Biology in Health and Disease Research Group, Oakland Research Institute, Oakland, California 94609
| | - James P. Buban
- Departments of Applied Science, Biochemistry & Molecular Medicine, Molecular and Cellular Biology, University of California, Davis, California 95616, and Lipid Biology in Health and Disease Research Group, Oakland Research Institute, Oakland, California 94609
| | - Henning Stahlberg
- Departments of Applied Science, Biochemistry & Molecular Medicine, Molecular and Cellular Biology, University of California, Davis, California 95616, and Lipid Biology in Health and Disease Research Group, Oakland Research Institute, Oakland, California 94609
| | - Michael N. Oda
- Departments of Applied Science, Biochemistry & Molecular Medicine, Molecular and Cellular Biology, University of California, Davis, California 95616, and Lipid Biology in Health and Disease Research Group, Oakland Research Institute, Oakland, California 94609
| | - John C. Voss
- Departments of Applied Science, Biochemistry & Molecular Medicine, Molecular and Cellular Biology, University of California, Davis, California 95616, and Lipid Biology in Health and Disease Research Group, Oakland Research Institute, Oakland, California 94609
| | - Atul N. Parikh
- Departments of Applied Science, Biochemistry & Molecular Medicine, Molecular and Cellular Biology, University of California, Davis, California 95616, and Lipid Biology in Health and Disease Research Group, Oakland Research Institute, Oakland, California 94609
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Abstract
BAR domains are proteins that sense and sculpt curved membranes in cells, furnishing a relatively well-studied example of mechanisms employed in cellular morphogenesis. We report a computational study of membrane bending by BAR domains at four levels of resolution, described by 1), all-atom molecular dynamics; 2), residue-based coarse-graining (resolving single amino acids and lipid molecules); 3), shape-based coarse-graining (resolving overall protein and membrane shapes); and 4), a continuum elastic membrane model. Membrane sculpting performed by BAR domains collectively is observed in agreement with experiments. Different arrangements of BAR domains on the membrane surface are found to lead to distinct membrane curvatures and bending dynamics.
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47
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Thomas MJ, Bhat S, Sorci-Thomas MG. Three-dimensional models of HDL apoA-I: implications for its assembly and function. J Lipid Res 2008; 49:1875-83. [PMID: 18515783 DOI: 10.1194/jlr.r800010-jlr200] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The purpose of this review is to highlight recent advances toward the refinement of a three-dimensional structure for lipid-bound apolipoprotein A-I (apoA-I) on recombinant HDL. Recently, X-ray crystallography has yielded a new structure for full-length, lipid-free apoA-I. Although this approach has not yet been successful in solving the three-dimensional structure of lipid-bound apoA-I, analysis of the X-ray structures has been of immense help in the interpretation of structural data obtained from other methods that yield structural information. Recent studies emphasize the use of mass spectrometry to unambiguously identify cross-linked peptides or to quantify solvent accessibility using hydrogen-deuterium exchange. The combination of mass spectrometry, molecular modeling, molecular dynamic analysis, and small-angle X-ray diffraction has provided additional structural information on apoA-I folding that complements previous approaches.
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Affiliation(s)
- Michael J Thomas
- Department of Biochemistry, Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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48
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Blanchette CD, Law R, Benner WH, Pesavento JB, Cappuccio JA, Walsworth V, Kuhn EA, Corzett M, Chromy BA, Segelke BW, Coleman MA, Bench G, Hoeprich PD, Sulchek TA. Quantifying size distributions of nanolipoprotein particles with single-particle analysis and molecular dynamic simulations. J Lipid Res 2008; 49:1420-30. [PMID: 18403317 DOI: 10.1194/jlr.m700586-jlr200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Self-assembly of purified apolipoproteins and phospholipids results in the formation of nanometer-sized lipoprotein complexes, referred to as nanolipoprotein particles (NLPs). These bilayer constructs are fully soluble in aqueous environments and hold great promise as a model system to aid in solubilizing membrane proteins. Size variability in the self-assembly process has been recognized for some time, yet limited studies have been conducted to examine this phenomenon. Understanding the source of this heterogeneity may lead to methods to mitigate heterogeneity or to control NLP size, which may be important for tailoring NLPs for specific membrane proteins. Here, we have used atomic force microscopy, ion mobility spectrometry, and transmission electron microscopy to quantify NLP size distributions on the single-particle scale, specifically focusing on assemblies with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and a recombinant apolipoprotein E variant containing the N-terminal 22 kDa fragment (E422k). Four discrete sizes of E422k/DMPC NLPs were identified by all three techniques, with diameters centered at approximately 14.5, 19, 23.5, and 28 nm. Computer simulations suggest that these sizes are related to the structure and number of E422k lipoproteins surrounding the NLPs and particles with an odd number of lipoproteins are consistent with the double-belt model, in which at least one lipoprotein adopts a hairpin structure.
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Affiliation(s)
- Craig D Blanchette
- Chemistry, Materials, and Life Sciences, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA
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49
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Abstract
In the absence of atomic structures of high-density lipoproteins in their lipid-bound states, many molecular models have been produced based on experimental data. Using molecular dynamics, we show that a recently proposed "solar-flares" model of discoidal high-density lipoprotein is implausible. Our simulations show a collapse of the protruding solar-flare loops and a notable protein rearrangement due to an energetically unfavorable orientation of the hydrophobic protein surface toward the aqueous solvent.
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50
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Chapter 11 Molecular Modeling of the Structural Properties and Formation of High-Density Lipoprotein Particles. CURRENT TOPICS IN MEMBRANES 2008. [DOI: 10.1016/s1063-5823(08)00011-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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