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Abstract
This Review illustrates the evaluation of permeability of lipid membranes from molecular dynamics (MD) simulation primarily using water and oxygen as examples. Membrane entrance, translocation, and exit of these simple permeants (one hydrophilic and one hydrophobic) can be simulated by conventional MD, and permeabilities can be evaluated directly by Fick's First Law, transition rates, and a global Bayesian analysis of the inhomogeneous solubility-diffusion model. The assorted results, many of which are applicable to simulations of nonbiological membranes, highlight the limitations of the homogeneous solubility diffusion model; support the utility of inhomogeneous solubility diffusion and compartmental models; underscore the need for comparison with experiment for both simple solvent systems (such as water/hexadecane) and well-characterized membranes; and demonstrate the need for microsecond simulations for even simple permeants like water and oxygen. Undulations, subdiffusion, fractional viscosity dependence, periodic boundary conditions, and recent developments in the field are also discussed. Last, while enhanced sampling methods and increasingly sophisticated treatments of diffusion add substantially to the repertoire of simulation-based approaches, they do not address directly the critical need for force fields with polarizability and multipoles, and constant pH methods.
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Affiliation(s)
- Richard M Venable
- Laboratory of Computational Biology, National Lung, Heart, and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Andreas Krämer
- Laboratory of Computational Biology, National Lung, Heart, and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Richard W Pastor
- Laboratory of Computational Biology, National Lung, Heart, and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
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102
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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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103
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Allender DW, Sodt AJ, Schick M. Cholesterol-Dependent Bending Energy Is Important in Cholesterol Distribution of the Plasma Membrane. Biophys J 2019; 116:2356-2366. [PMID: 31023537 DOI: 10.1016/j.bpj.2019.03.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/19/2019] [Accepted: 03/21/2019] [Indexed: 11/16/2022] Open
Abstract
We consider the plasma membrane that contains a cholesterol molar fraction of 0.4 and ask how that cholesterol is distributed between the two leaves. Because of the rapid flip-flop of cholesterol between leaves, we assume that its distribution is determined by the equality of its chemical potentials in the two leaves. When we consider only the contributions of entropy and interactions to the cholesterol chemical potential in our model system, we find, not surprisingly, that the cholesterol is mostly in the outer leaf because of the strong attraction between cholesterol and sphingomyelin (SM), which is predominantly in that leaf. We find 72% there. We then include the contribution from the bending energy in each leaf that must be overcome to join the leaves in a flat bilayer. The product of bending modulus and spontaneous curvature is obtained from simulation. We find that the addition of cholesterol to the outer leaf reduces the spontaneous curvature, which is initially positive, until it passes through zero when the molar fraction of cholesterol in the outer leaf is 0.28. Additional cholesterol is driven toward the inner leaf by the sphingomyelin phosphatidylcholine mixture. This is resisted by the bending energy contribution to the inner leaf. We find, again by simulation, that the addition of cholesterol monotonically increases the magnitude of the spontaneous curvature of the inner leaf, which is negative. This increases its bending energy. We conclude that, as a result of these competing effects, the percentage of cholesterol in the outer leaf is reduced to ∼63 ± 6%.
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Affiliation(s)
- D W Allender
- Department of Physics, University of Washington, Seattle, Washington; Department of Physics, Kent State University, Kent, Ohio
| | - A J Sodt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, Maryland
| | - M Schick
- Department of Physics, University of Washington, Seattle, Washington.
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104
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Wang E, Klauda JB. Structure and Permeability of Ceramide Bilayers and Multilayers. J Phys Chem B 2019; 123:2525-2535. [DOI: 10.1021/acs.jpcb.9b00037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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105
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Leonard AN, Wang E, Monje-Galvan V, Klauda JB. Developing and Testing of Lipid Force Fields with Applications to Modeling Cellular Membranes. Chem Rev 2019; 119:6227-6269. [DOI: 10.1021/acs.chemrev.8b00384] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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106
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Watanabe N, Goto Y, Suga K, Nyholm TKM, Slotte JP, Umakoshi H. Solvatochromic Modeling of Laurdan for Multiple Polarity Analysis of Dihydrosphingomyelin Bilayer. Biophys J 2019; 116:874-883. [PMID: 30819567 DOI: 10.1016/j.bpj.2019.01.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 01/17/2019] [Accepted: 01/28/2019] [Indexed: 01/28/2023] Open
Abstract
The hydration properties of the interface between lipid bilayers and bulk water are important for determining membrane characteristics. Here, the emission properties of a solvent-sensitive fluorescence probe, 6-lauroyl-2-dimethylamino naphthalene (Laurdan), were evaluated in lipid bilayer systems composed of the sphingolipids D-erythro-N-palmitoyl-sphingosylphosphorylcholine (PSM) and D-erythro-N-palmitoyl-dihydrosphingomyelin (DHPSM). The glycerophospholipids 1-palmitoyl-2-palmitoyl-sn-glycero-3-phosphocholine and 1-oleoyl-2-oleoyl-sn-glycero-3-phosphocholine were used as controls. The fluorescence properties of Laurdan in sphingolipid bilayers indicated multiple excited states according to the results obtained from the emission spectra, fluorescence anisotropy, and the center-of-mass spectra during the decay time. Deconvolution of the Laurdan emission spectra into four components based on the solvent model enabled us to identify the varieties of hydration and the configurational states derived from intermolecular hydrogen bonding in sphingolipids. Sphingolipids showed specific, interfacial hydration properties stemming from their intra- and intermolecular hydrogen bonds. Particularly, the Laurdan in DHPSM revealed more hydrated properties compared to PSM, even though DHPSM has a higher Tm than PSM. Because DHPSM forms hydrogen bonds with water molecules (in 2NH configurational functional groups), the interfacial region of the DHPSM bilayer was expected to be in a highly polar environment. The careful analysis of Laurdan emission spectra through the four-component deconvolution in this study provides important insights for understanding the multiple polarity in the lipid membrane.
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Affiliation(s)
- Nozomi Watanabe
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Yuka Goto
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Keishi Suga
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Thomas K M Nyholm
- Department of Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - J Peter Slotte
- Department of Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Hiroshi Umakoshi
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
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107
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Doktorova M, LeVine MV, Khelashvili G, Weinstein H. A New Computational Method for Membrane Compressibility: Bilayer Mechanical Thickness Revisited. Biophys J 2019; 116:487-502. [PMID: 30665693 DOI: 10.1016/j.bpj.2018.12.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 11/27/2018] [Accepted: 12/20/2018] [Indexed: 01/24/2023] Open
Abstract
Because lipid bilayers can bend and stretch in ways similar to thin elastic sheets, physical models of bilayer deformation have utilized mechanical constants such as the moduli for bending rigidity (κC) and area compressibility (KA). However, the use of these models to quantify the energetics of membrane deformation associated with protein-membrane interactions, and the membrane response to stress is often hampered by the shortage of experimental data suitable for the estimation of the mechanical constants of various lipid mixtures. Although computational tools such as molecular dynamics simulations can provide alternative means to estimate KA values, current approaches suffer significant technical limitations. Here, we present a novel, to our knowledge, computational framework that allows for a direct estimation of KA values for individual bilayer leaflets. The theory is based on the concept of elasticity and derives KA from real-space analysis of local thickness fluctuations sampled in molecular dynamics simulations. We explore and validate the model on a large set of single and multicomponent bilayers of different lipid compositions and sizes, simulated at different temperatures. The calculated bilayer compressibility moduli agree with values estimated previously from experiments and those obtained from a standard computational method based on a series of constrained tension simulations. We further validate our framework in a comparison with an existing polymer brush model and confirm the polymer brush model's predicted linear relationship with proportionality coefficient of 24, using elastic parameters calculated from the simulation trajectories. The robustness of the results that emerge from the method allows us to revisit the origins of the bilayer mechanical (compressible) thickness and in particular its dependence on acyl-chain unsaturation and the presence of cholesterol.
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Affiliation(s)
- Milka Doktorova
- Tri-Institutional PhD Program in Computational Biology and Medicine, Weill Cornell Medical College, New York, New York.
| | - Michael V LeVine
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York; The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Greenberg Center, New York, New York
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York; The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Greenberg Center, New York, New York
| | - Harel Weinstein
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York; The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Greenberg Center, New York, New York
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108
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Molugu TR, Brown MF. Cholesterol Effects on the Physical Properties of Lipid Membranes Viewed by Solid-state NMR Spectroscopy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1115:99-133. [PMID: 30649757 DOI: 10.1007/978-3-030-04278-3_5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In this chapter, we review the physical properties of lipid/cholesterol mixtures involving studies of model membranes using solid-state NMR spectroscopy. The approach allows one to quantify the average membrane structure, fluctuations, and elastic deformation upon cholesterol interaction. Emphasis is placed on understanding the membrane structural deformation and emergent fluctuations at an atomistic level. Lineshape measurements using solid-state NMR spectroscopy give equilibrium structural properties, while relaxation time measurements study the molecular dynamics over a wide timescale range. The equilibrium properties of glycerophospholipids, sphingolipids, and their binary and tertiary mixtures with cholesterol are accessible. Nonideal mixing of cholesterol with other lipids explains the occurrence of liquid-ordered domains. The entropic loss upon addition of cholesterol to sphingolipids is less than for glycerophospholipids, and may drive formation of lipid rafts. The functional dependence of 2H NMR spin-lattice relaxation (R 1Z) rates on segmental order parameters (S CD) for lipid membranes is indicative of emergent viscoelastic properties. Addition of cholesterol shows stiffening of the bilayer relative to the pure lipids and this effect is diminished for lanosterol. Opposite influences of cholesterol and detergents on collective dynamics and elasticity at an atomistic scale can potentially affect lipid raft formation in cellular membranes.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA. .,Department of Physics, University of Arizona, Tucson, AZ, USA.
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109
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Monje-Galvan V, Warburton L, Klauda JB. Setting Up All-Atom Molecular Dynamics Simulations to Study the Interactions of Peripheral Membrane Proteins with Model Lipid Bilayers. Methods Mol Biol 2019; 1949:325-339. [PMID: 30790265 DOI: 10.1007/978-1-4939-9136-5_22] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
All-atom molecular dynamics (MD) simulations enable the study of biological systems at atomic detail, complement the understanding gained from experiment, and can also motivate experimental techniques to further examine a given biological process. This method is based on statistical mechanics; it predicts the trajectory of atoms over time by solving Newton's Laws of motion taking into account all forces. Here, we describe the use of this methodology to study the interaction between peripheral membrane proteins and a lipid bilayer. Specifically, we provide step-by-step instructions to set up MD simulations to study the binding and interaction of the amphipathic helix of Osh4, a lipid transport protein, and Thanatin, an antimicrobial peptide (AMP), with model lipid bilayers using both fully detailed lipid tails and the highly mobile membrane-mimetic (HMMM) method to enhance conformational sampling.
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Affiliation(s)
- Viviana Monje-Galvan
- Department of Chemistry, The University of Chicago, Chicago, IL, USA. .,Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA.
| | - Linnea Warburton
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA.,Biophysics Program, University of Maryland, College Park, MD, USA
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110
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Lee J, Patel DS, Ståhle J, Park SJ, Kern NR, Kim S, Lee J, Cheng X, Valvano MA, Holst O, Knirel YA, Qi Y, Jo S, Klauda JB, Widmalm G, Im W. CHARMM-GUI Membrane Builder for Complex Biological Membrane Simulations with Glycolipids and Lipoglycans. J Chem Theory Comput 2018; 15:775-786. [PMID: 30525595 DOI: 10.1021/acs.jctc.8b01066] [Citation(s) in RCA: 322] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Glycolipids (such as glycoglycerolipids, glycosphingolipids, and glycosylphosphatidylinositol) and lipoglycans (such as lipopolysaccharides (LPS), lipooligosaccharides (LOS), mycobacterial lipoarabinomannan, and mycoplasma lipoglycans) are typically found on the surface of cell membranes and play crucial roles in various cellular functions. Characterizing their structure and dynamics at the molecular level is essential to understand their biological roles, but systematic generation of glycolipid and lipoglycan structures is challenging because of great variations in lipid structures and glycan sequences (i.e., carbohydrate types and their linkages). To facilitate the generation of all-atom glycolipid/LPS/LOS structures, we have developed Glycolipid Modeler and LPS Modeler in CHARMM-GUI ( http://www.charmm-gui.org ), a web-based interface that simplifies building of complex biological simulation systems. In addition, we have incorporated these modules into Membrane Builder so that users can readily build a complex symmetric or asymmetric biological membrane system with various glycolipids and LPS/LOS. These tools are expected to be useful in innovative and novel glycolipid/LPS/LOS modeling and simulation research by easing tedious and intricate steps in modeling complex biological systems and shall provide insight into structures, dynamics, and underlying mechanisms of complex glycolipid-/LPS-/LOS-containing biological membrane systems.
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Affiliation(s)
- Jumin Lee
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States
| | - Dhilon S Patel
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States
| | - Jonas Ståhle
- Department of Organic Chemistry, Arrhenius Laboratory , Stockholm University , SE-106 91 Stockholm , Sweden
| | - Sang-Jun Park
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States
| | - Nathan R Kern
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States
| | - Seonghoon Kim
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States
| | - Joonseong Lee
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States
| | - Xi Cheng
- State Key Laboratory of Drug Research , Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zuchongzhi Road , Shanghai 201203 , China
| | - Miguel A Valvano
- Wellcome-Wolfson Institute for Experimental Medicine , Queen's University Belfast BT9 7BL , United Kingdom
| | - Otto Holst
- Division of Structural Biochemistry, Research Center Borstel , Airway Research Center North, Member of the German Center for Lung Research (DZL) , D-23845 Borstel , Germany
| | - Yuriy A Knirel
- N. D. Zelinsky Institute of Organic Chemistry , Russian Academy of Sciences , 119991 Moscow , Russia
| | - 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
| | - Sunhwan Jo
- Leadership Computing Facility , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering and the Biophysics Graduate Program , University of Maryland , College Park , Maryland 20742 , United States
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory , Stockholm University , SE-106 91 Stockholm , Sweden
| | - Wonpil Im
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States
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111
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Hantal G, Fábián B, Sega M, Jójárt B, Jedlovszky P. Effect of general anesthetics on the properties of lipid membranes of various compositions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:594-609. [PMID: 30571949 DOI: 10.1016/j.bbamem.2018.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/05/2018] [Accepted: 12/13/2018] [Indexed: 10/27/2022]
Abstract
Computer simulations of four lipid membranes of different compositions, namely neat DPPC and PSM, and equimolar DPPC-cholesterol and PSM-cholesterol mixtures, are performed in the presence and absence of the general anesthetics diethylether and sevoflurane both at 1 and 600 bar. The results are analyzed in order to identify membrane properties that are potentially related to the molecular mechanism of anesthesia, namely that change in the same way in any membrane with any anesthetics, and change oppositely with increasing pressure. We find that the lateral lipid density satisfies both criteria: it is decreased by anesthetics and increased by pressure. This anesthetic-induced swelling is attributed to only those anesthetic molecules that are located close to the boundary of the apolar phase. This lateral expansion is found to lead to increased lateral mobility of the lipids, an effect often thought to be related to general anesthesia; to an increased fraction of the free volume around the outer preferred position of anesthetics; and to the decrease of the lateral pressure in the nearby range of the ester and amide groups, a region into which anesthetic molecules already cannot penetrate. All these changes are reverted by the increase of pressure. Another important finding of this study is that cholesterol has an opposite effect on the membrane properties than anesthetics, and, correspondingly, these changes are less marked in the presence of cholesterol. Therefore, changes in the membrane that can lead to general anesthesia are expected to occur in the membrane domains of low cholesterol content.
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Affiliation(s)
- György Hantal
- Faculty of Physics, University of Vienna, Sensengasse 8/9, A-1090 Vienna, Austria
| | - Balázs Fábián
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary; Institut UTINAM (CNRS UMR 6213), Université Bourgogne Franche-Comté, 16 route de Gray, F-25030 Besançon, France
| | - Marcello Sega
- Faculty of Physics, University of Vienna, Sensengasse 8/9, A-1090 Vienna, Austria
| | - Balázs Jójárt
- Institute of Food Engineering, University of Szeged, Moszkvai krt 5-7, H-6725 Szeged, Hungary
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka utca 6, H-3300 Eger, Hungary.
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112
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Seo S, Shinoda W. SPICA Force Field for Lipid Membranes: Domain Formation Induced by Cholesterol. J Chem Theory Comput 2018; 15:762-774. [PMID: 30514078 DOI: 10.1021/acs.jctc.8b00987] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heterogeneity is essential for multicomponent lipid membranes. Especially, sterol-induced domain formation in membranes has recently attracted attention because of its biological importance. To investigate such membrane domains at the molecular level, coarse-grained molecular dynamics (CG-MD) simulations are a promising approach since they allow one to consider the temporal and spatial scales involved in domain formation. In this work, we present a new CG force field, named SPICA, which can accurately predict domain formation within various lipids in membranes. The SPICA force field was developed as an extension of a previous CG model, known as SDK (Shinoda-DeVane-Klein), in which membrane properties such as tension, elasticity, and structure are well reproduced. By examining domain formation in a series of ternary lipid bilayers, we observed a separation into liquid-ordered and liquid-disordered phases fully consistent with experimental observations. Importantly, it is shown that the SPICA force field can detect the different phase behavior that results from subtle differences in the lipid composition of the bilayer.
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Affiliation(s)
- Sangjae Seo
- Department of Materials Chemistry , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8603 , Japan
| | - Wataru Shinoda
- Department of Materials Chemistry , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8603 , Japan
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113
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Wang E, Klauda JB. Models for the Stratum Corneum Lipid Matrix: Effects of Ceramide Concentration, Ceramide Hydroxylation, and Free Fatty Acid Protonation. J Phys Chem B 2018; 122:11996-12008. [DOI: 10.1021/acs.jpcb.8b06188] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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114
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Smith AK, Klimov DK. Molecular Dynamics Investigation of the Ternary Bilayer Formed by Saturated Phosphotidylcholine, Sphingomyelin, and Cholesterol. J Phys Chem B 2018; 122:11311-11325. [DOI: 10.1021/acs.jpcb.8b07256] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Amy K. Smith
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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115
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Ramakrishnan N, Bradley RP, Tourdot RW, Radhakrishnan R. Biophysics of membrane curvature remodeling at molecular and mesoscopic lengthscales. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:273001. [PMID: 29786613 PMCID: PMC6066392 DOI: 10.1088/1361-648x/aac702] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
At the micron scale, where cell organelles display an amazing complexity in their shape and organization, the physical properties of a biological membrane can be better-understood using continuum models subject to thermal (stochastic) undulations. Yet, the chief orchestrators of these complex and intriguing shapes are a specialized class of membrane associating often peripheral proteins called curvature remodeling proteins (CRPs) that operate at the molecular level through specific protein-lipid interactions. We review multiscale methodologies to model these systems at the molecular as well as at the mesoscopic and cellular scales, and also present a free energy perspective of membrane remodeling through the organization and assembly of CRPs. We discuss the morphological space of nearly planar to highly curved membranes, methods to include thermal fluctuations, and review studies that model such proteins as curvature fields to describe the emergent curved morphologies. We also discuss several mesoscale models applied to a variety of cellular processes, where the phenomenological parameters (such as curvature field strength) are often mapped to models of real systems based on molecular simulations. Much insight can be gained from the calculation of free energies of membranes states with protein fields, which enable accurate mapping of the state and parameter values at which the membrane undergoes morphological transformations such as vesiculation or tubulation. By tuning the strength, anisotropy, and spatial organization of the curvature-field, one can generate a rich array of membrane morphologies that are highly relevant to shapes of several cellular organelles. We review applications of these models to budding of vesicles commonly seen in cellular signaling and trafficking processes such as clathrin mediated endocytosis, sorting by the ESCRT protein complexes, and cellular exocytosis regulated by the exocyst complex. We discuss future prospects where such models can be combined with other models for cytoskeletal assembly, and discuss their role in understanding the effects of cell membrane tension and the mechanics of the extracellular microenvironment on cellular processes.
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Affiliation(s)
- N Ramakrishnan
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, United States of America
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116
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Lundborg M, Wennberg CL, Narangifard A, Lindahl E, Norlén L. Predicting drug permeability through skin using molecular dynamics simulation. J Control Release 2018; 283:269-279. [PMID: 29864475 DOI: 10.1016/j.jconrel.2018.05.026] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 04/27/2018] [Accepted: 05/21/2018] [Indexed: 01/23/2023]
Abstract
Understanding and predicting permeability of compounds through skin is of interest for transdermal delivery of drugs and for toxicity predictions of chemicals. We show, using a new atomistic molecular dynamics model of the skin's barrier structure, itself validated against near-native cryo-electron microscopy data from human skin, that skin permeability to the reference compounds benzene, DMSO (dimethyl sulfoxide), ethanol, codeine, naproxen, nicotine, testosterone and water can be predicted. The permeability results were validated against skin permeability data in the literature. We have investigated the relation between skin barrier molecular organization and permeability using atomistic molecular dynamics simulation. Furthermore, it is shown that the calculated mechanism of action differs between the five skin penetration enhancers Azone, DMSO, oleic acid, stearic acid and water. The permeability enhancing effect of a given penetration enhancer depends on the permeating compound and on the concentration of penetration enhancer inside the skin's barrier structure. The presented method may open the door for computer based screening of the permeation of drugs and toxic compounds through skin.
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Affiliation(s)
| | | | - Ali Narangifard
- ERCO Pharma AB, Science for Life Laboratory, Solna, Sweden; Department of Medicine, Solna (MedS), Karolinska Institute, Solna, Sweden
| | - Erik Lindahl
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden; Swedish eScience Research Center, Department of Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Lars Norlén
- Department of Cell and Molecular Biology (CMB), Karolinska Institute, Solna, Sweden; Dermatology Clinic, Karolinska University Hospital, Solna, Sweden.
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117
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Kumari P, Kaur S, Sharma S, Kashyap HK. Impact of amphiphilic molecules on the structure and stability of homogeneous sphingomyelin bilayer: Insights from atomistic simulations. J Chem Phys 2018; 148:165102. [DOI: 10.1063/1.5021310] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Pratibha Kumari
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Supreet Kaur
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Shobha Sharma
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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118
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Lundborg M, Narangifard A, Wennberg CL, Lindahl E, Daneholt B, Norlén L. Human skin barrier structure and function analyzed by cryo-EM and molecular dynamics simulation. J Struct Biol 2018; 203:149-161. [PMID: 29702212 DOI: 10.1016/j.jsb.2018.04.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/19/2018] [Accepted: 04/22/2018] [Indexed: 11/29/2022]
Abstract
In the present study we have analyzed the molecular structure and function of the human skin's permeability barrier using molecular dynamics simulation validated against cryo-electron microscopy data from near native skin. The skin's barrier capacity is located to an intercellular lipid structure embedding the cells of the superficial most layer of skin - the stratum corneum. According to the splayed bilayer model (Iwai et al., 2012) the lipid structure is organized as stacked bilayers of ceramides in a splayed chain conformation with cholesterol associated with the ceramide sphingoid moiety and free fatty acids associated with the ceramide fatty acid moiety. However, knowledge about the lipid structure's detailed molecular organization, and the roles of its different lipid constituents, remains circumstantial. Starting from a molecular dynamics model based on the splayed bilayer model, we have, by stepwise structural and compositional modifications, arrived at a thermodynamically stable molecular dynamics model expressing simulated electron microscopy patterns matching original cryo-electron microscopy patterns from skin extremely closely. Strikingly, the closer the individual molecular dynamics models' lipid composition was to that reported in human stratum corneum, the better was the match between the models' simulated electron microscopy patterns and the original cryo-electron microscopy patterns. Moreover, the closest-matching model's calculated water permeability and thermotropic behaviour were found compatible with that of human skin. The new model may facilitate more advanced physics-based skin permeability predictions of drugs and toxicants. The proposed procedure for molecular dynamics based analysis of cellular cryo-electron microscopy data might be applied to other biomolecular systems.
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Affiliation(s)
| | - Ali Narangifard
- ERCO Pharma AB, Science for Life Laboratory, Solna, Sweden; Department of Medicine, Solna (MedS), Karolinska Institute, Solna, Sweden
| | - Christian L Wennberg
- ERCO Pharma AB, Science for Life Laboratory, Solna, Sweden; Swedish eScience Research Center, Department of Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Erik Lindahl
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden; Swedish eScience Research Center, Department of Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Bertil Daneholt
- Department of Cell and Molecular Biology (CMB), Karolinska Institute, Stockholm, Sweden
| | - Lars Norlén
- Department of Cell and Molecular Biology (CMB), Karolinska Institute, Stockholm, Sweden; Dermatology Clinic, Karolinska University Hospital, Stockholm, Sweden.
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119
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Arsov Z, González-Ramírez EJ, Goñi FM, Tristram-Nagle S, Nagle JF. Phase behavior of palmitoyl and egg sphingomyelin. Chem Phys Lipids 2018; 213:102-110. [PMID: 29689259 DOI: 10.1016/j.chemphyslip.2018.03.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/02/2018] [Accepted: 03/06/2018] [Indexed: 01/28/2023]
Abstract
Despite the biological significance of sphingomyelins (SMs), there is far less structural information available for SMs compared to glycerophospholipids. Considerable confusion exists in the literature regarding even the phase behavior of SM bilayers. This work studies both palmitoyl (PSM) and egg sphingomyelin (ESM) in the temperature regime from 3 °C to 55 °C using X-ray diffraction and X-ray diffuse scattering on hydrated, oriented thick bilayer stacks. We observe clear evidence for a ripple phase for ESM in a large temperature range from 3 °C to the main phase transition temperature (TM) of ∼38 °C. This unusual stability of the ripple phase was not observed for PSM, which was in a gel phase at 3 °C, with a gel-to-ripple transition at ∼24 °C and a ripple-to-fluid transition at ∼41 °C. We also report structural results for all phases. In the gel phase at 3 °C, PSM has chains tilted by ∼30° with an area/lipid ∼45 Å2 as determined by wide angle X-ray scattering. The ripple phases for both PSM and ESM have temperature dependent ripple wavelengths that are ∼145 Å near 30 °C. In the fluid phase, our electron density profiles combined with volume measurements allow calculation of area/lipid to be ∼64 Å2 for both PSM and ESM, which is larger than that from most of the previous molecular dynamics simulations and experimental studies. Our study demonstrates that oriented lipid films are particularly well-suited to characterize ripple phases since the scattering pattern is much better resolved than in unoriented samples.
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Affiliation(s)
- Zoran Arsov
- Department of Condensed Matter Physics, Laboratory of Biophysics, Jozef Stefan Institute, 1000 Ljubljana, Slovenia
| | - Emilio J González-Ramírez
- Instituto Biofísika (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, 48080 Bilbao, Spain
| | - Felix M Goñi
- Instituto Biofísika (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, 48080 Bilbao, Spain
| | | | - John F Nagle
- Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
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120
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Effect of 5-trans Isomer of Arachidonic Acid on Model Liposomal Membranes Studied by a Combined Simulation and Experimental Approach. J Membr Biol 2018; 251:475-489. [PMID: 29610947 DOI: 10.1007/s00232-018-0029-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Accepted: 03/08/2018] [Indexed: 02/07/2023]
Abstract
Unsaturated fatty acids are found in humans predominantly in the cis configuration. Fatty acids in the trans configuration are primarily the result of human processing (trans fats), but can also be formed endogenously by radical stress. The cis-trans isomerization of fatty acids by free radicals could be connected to several pathologies. Trans fats have been linked to an increased risk of coronary artery disease; however, the reasons for the resulting pathogenesis remain unclear. Here, we investigate the effect of a mono-trans isomer of arachidonic acid (C20:4-5trans, 8cis, 11cis, 14cis) produced by free radicals in physiological concentration on a model erythrocyte membrane using a combined experimental and theoretical approach. Molecular Dynamics (MD) simulations of two model lipid bilayers containing arachidonic acid and its 5-trans isomer in 3 mol% were carried out for this purpose. The 5-trans isomer formation in the phospholipids was catalyzed by HOCH2CH2S· radicals, generated from the corresponding thiol by γ-irradiation, in multilamellar vesicles of SAPC. Large unilamellar vesicles were made by the extrusion method (LUVET) as a biomimetic model for cis-trans isomerization. Atomic Force Microscopy and Dynamic Light Scattering were used to measure the average size, morphology, and the z-potential of the liposomes. Both results from MD simulations and experiments are in agreement and indicate that the two model membranes display different physicochemical properties in that the bilayers containing the trans fatty acids were more ordered and more rigid than those containing solely the cis arachidonic acid. Correspondingly, the average size of the liposomes containing trans isomers was smaller than the ones without.
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121
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Wang E, Klauda JB. Simulations of Pure Ceramide and Ternary Lipid Mixtures as Simple Interior Stratum Corneum Models. J Phys Chem B 2018; 122:2757-2768. [DOI: 10.1021/acs.jpcb.8b00348] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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122
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Leonard AN, Simmonett AC, Pickard FC, Huang J, Venable RM, Klauda JB, Brooks BR, Pastor RW. Comparison of Additive and Polarizable Models with Explicit Treatment of Long-Range Lennard-Jones Interactions Using Alkane Simulations. J Chem Theory Comput 2018; 14:948-958. [PMID: 29268012 DOI: 10.1021/acs.jctc.7b00948] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Long-range Lennard-Jones (LJ) interactions have a significant impact on the structural and thermodynamic properties of nonpolar systems. While several methods have been introduced for the treatment of long-range LJ interactions in molecular dynamics (MD) simulations, increased accuracy and extended applicability is required for anisotropic systems such as lipid bilayers. The recently refined Lennard-Jones particle-mesh Ewald (LJ-PME) method extends the particle-mesh Ewald (PME) method to long-range LJ interactions and is suitable for use with anisotropic systems. Implementation of LJ-PME with the CHARMM36 (C36) additive and CHARMM Drude polarizable force fields improves agreement with experiment for density, isothermal compressibility, surface tension, viscosity, translational diffusion, and 13C T1 relaxation times of pure alkanes. Trends in the temperature dependence of the density and isothermal compressibility of hexadecane are also improved. While the C36 additive force field with LJ-PME remains a useful model for liquid alkanes, the Drude polarizable force field with LJ-PME is more accurate for nearly all quantities considered. LJ-PME is also preferable to the isotropic long-range correction for hexadecane because the molecular order extends to nearly 20 Å, well beyond the usual 10-12 Å cutoffs used in most simulations.
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Affiliation(s)
- Alison N Leonard
- Biophysics Program, University of Maryland , College Park, Maryland 20742, United States
| | - Andrew C Simmonett
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Frank C Pickard
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Jing Huang
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States.,Department of Pharmaceutical Science, School of Pharmacy, University of Maryland , 20 Penn Street, Baltimore, Maryland 21201, United States
| | - Richard M Venable
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Jeffery B Klauda
- Biophysics Program, University of Maryland , College Park, Maryland 20742, United States.,Department of Chemical and Biomolecular Engineering, University of Maryland , College Park, Maryland 20742, United States
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
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123
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Adams M, Wang E, Zhuang X, Klauda JB. Simulations of simple Bovine and Homo sapiens outer cortex ocular lens membrane models with a majority concentration of cholesterol. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:2134-2144. [PMID: 29169746 DOI: 10.1016/j.bbamem.2017.11.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 11/06/2017] [Accepted: 11/17/2017] [Indexed: 12/31/2022]
Abstract
The lipid composition of bovine and human ocular lens membranes has been probed, and a variety of lipids have been found including phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (SM), and cholesterol (CHOL) with cholesterol being present in particularly high concentrations. In this study, we use the all-atom CHARMM36 force field to simulate binary, ternary, and quaternary mixtures as models of the ocular lens. High concentration of cholesterol, in combination with different and varying diversity of phospholipids (PL) and sphingolipids (SL), affect the structure of the ocular lens lipid bilayer. The following analyses were done for each simulation: surface area per lipid, component surface area per lipid, deuterium order parameters (SCD), electron density profiles (EDP), membrane thickness, hydrogen bonding, radial distribution functions, clustering, and sterol tilt angle distribution. The SCD show significant bilayer alignment and packing in cholesterol-rich bilayers. The EDP show the transition from liquid crystalline to liquid ordered with the addition of cholesterol. Hydrogen bonds in our systems show the tendency for intramolecular interactions between cholesterol and fully saturated lipid tails for less complex bilayers. But with an increased number of components in the bilayer, the acyl chain of the lipids becomes a less important characteristic, and the headgroup of the lipid becomes more significant. Overall, cholesterol is the driving force of membrane structure of the ocular lens membrane where interactions between cholesterol, PL, and SL determine structure and function of the biomembrane. The goal of this work is to develop a baseline for further study of more physiologically realistic ocular lens lipid membranes. This article is part of a Special Issue entitled: Emergence of Complex Behavior in Biomembranes edited by Marjorie Longo.
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Affiliation(s)
- Mark Adams
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA
| | - Eric Wang
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA
| | - Xiaohong Zhuang
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA; Biophysics Program, University of Maryland, College Park, MD 20742, USA.
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124
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Edler E, Stein M. Recognition and stabilization of geranylgeranylated human Rab5 by the GDP Dissociation Inhibitor (GDI). Small GTPases 2017; 10:227-242. [PMID: 29065764 PMCID: PMC6548291 DOI: 10.1080/21541248.2017.1371268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The small GTPase Rab5 is the key regulator of early endosomal fusion. It is post-translationally modified by covalent attachment of two geranylgeranyl (GG) chains to adjacent cysteine residues of the C-terminal hypervariable region (HVR). The GDP dissociation inhibitor (GDI) recognizes membrane-associated Rab5(GDP) and serves to release it into the cytoplasm where it is kept in a soluble state. A detailed new structural and dynamic model for human Rab5(GDP) recognition and binding with human GDI at the early endosome membrane and in its dissociated state is presented. In the cytoplasm, the GDI protein accommodates the GG chains in a transient hydrophobic binding pocket. In solution, two different binding modes of the isoprenoid chains inserted into the hydrophobic pocket of the Rab5(GDP):GDI complex can be identified. This equilibrium between the two states helps to stabilize the protein-protein complex in solution. Interprotein contacts between the Rab5 switch regions and characteristic patches of GDI residues from the Rab binding platform (RBP) and the C-terminus coordinating region (CCR) reveal insight on the formation of such a stable complex. GDI binding to membrane-anchored Rab5(GDP) is initially mediated by the solvent accessible switch regions of the Rab-specific RBP. Formation of the membrane-associated Rab5(GDP):GDI complex induces a GDI reorientation to establish additional interactions with the Rab5 HVR. These results allow to devise a detailed structural model for the process of extraction of GG-Rab5(GDP) by GDI from the membrane and the dissociation from targeting factors and effector proteins prior to GDI binding.
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Affiliation(s)
- Eileen Edler
- a Molecular Simulations and Design Group, Max Planck Institute for Dynamics of Complex Technical Systems , Magdeburg , Germany
| | - Matthias Stein
- a Molecular Simulations and Design Group, Max Planck Institute for Dynamics of Complex Technical Systems , Magdeburg , Germany
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125
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Wang E, Klauda JB. Molecular Dynamics Simulations of Ceramide and Ceramide-Phosphatidylcholine Bilayers. J Phys Chem B 2017; 121:10091-10104. [PMID: 29017324 DOI: 10.1021/acs.jpcb.7b08967] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent studies in lipid raft formation and stratum corneum permeability have focused on the role of ceramides (CER). In this study, we use the all-atom CHARMM36 (C36) force field to simulate bilayers using N-palmitoylsphingosine (CER16) or α-hydroxy-N-stearoyl phytosphingosine (CER[AP]) in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), which serve as general membrane models. Conditions are replicated from experimental studies for comparison purposes, and concentration (XCER) is varied to probe the effect of CER on these systems. Comparisons with experiment based on deuterium order parameters and bilayer thickness demonstrate good agreement, thus supporting further use of the C36 force field. CER concentration is shown to have a profound effect on nearly all membrane properties including surface area per lipid, chain order and tilt, area compressibility moduli, bilayer thickness, hydrogen bonding, and lipid clustering. Hydrogen bonding in particular can significantly affect other membrane properties and can even encourage transition to a gel phase. Despite CER's tendency to condense the membrane, an expansion of CER lipids with increasing XCER is possible depending on how the balance between various hydrogen-bond pairs and lipid clustering is perturbed. Based on gel phase transitions, support is given for phytosphingosine's role as a hydrogen-bond bridge between sphingosine ordered domains in the stratum corneum.
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Affiliation(s)
- Eric Wang
- Department of Chemical and Biomolecular Engineering and ‡Biophysics Graduate Program, University of Maryland , College Park, Maryland 20742, United States
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering and ‡Biophysics Graduate Program, University of Maryland , College Park, Maryland 20742, United States
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126
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Sollich M, Yoshinaga MY, Häusler S, Price RE, Hinrichs KU, Bühring SI. Heat Stress Dictates Microbial Lipid Composition along a Thermal Gradient in Marine Sediments. Front Microbiol 2017; 8:1550. [PMID: 28878741 PMCID: PMC5572230 DOI: 10.3389/fmicb.2017.01550] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 07/31/2017] [Indexed: 12/17/2022] Open
Abstract
Temperature exerts a first-order control on microbial populations, which constantly adjust the fluidity and permeability of their cell membrane lipids to minimize loss of energy by ion diffusion across the membrane. Analytical advances in liquid chromatography coupled to mass spectrometry have allowed the detection of a stunning diversity of bacterial and archaeal lipids in extreme environments such as hot springs, hydrothermal vents and deep subsurface marine sediments. Here, we investigated a thermal gradient from 18 to 101°C across a marine sediment field and tested the hypothesis that cell membrane lipids provide a major biochemical basis for the bioenergetics of archaea and bacteria under heat stress. This paper features a detailed lipidomics approach with the focus on membrane lipid structure-function. Membrane lipids analyzed here include polar lipids of bacteria and polar and core lipids of archaea. Reflecting the low permeability of their ether-linked isoprenoids, we found that archaeal polar lipids generally dominate over bacterial lipids in deep layers of the sediments influenced by hydrothermal fluids. A close examination of archaeal and bacterial lipids revealed a membrane quandary: not only low permeability, but also increased fluidity of membranes are required as a unified property of microbial membranes for energy conservation under heat stress. For instance, bacterial fatty acids were composed of longer chain lengths in concert with higher degree of unsaturation while archaea modified their tetraethers by incorporation of additional methyl groups at elevated sediment temperatures. It is possible that these configurations toward a more fluidized membrane at elevated temperatures are counterbalanced by the high abundance of archaeal glycolipids and bacterial sphingolipids, which could reduce membrane permeability through strong intermolecular hydrogen bonding. Our results provide a new angle for interpreting membrane lipid structure-function enabling archaea and bacteria to survive and grow in hydrothermal systems.
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Affiliation(s)
- Miriam Sollich
- University of Bremen, MARUM Center for Marine Environmental SciencesBremen, Germany
| | - Marcos Y Yoshinaga
- University of Bremen, MARUM Center for Marine Environmental SciencesBremen, Germany.,Institute of Chemistry, University of São PauloSão Paulo, Brazil
| | - Stefan Häusler
- Department of Molecular Ecology, Max Planck Institute for Marine MicrobiologyBremen, Germany
| | - Roy E Price
- University of Bremen, MARUM Center for Marine Environmental SciencesBremen, Germany.,School of Marine and Atmospheric Sciences, Stony Brook University, Stony BrookNY, United States
| | - Kai-Uwe Hinrichs
- University of Bremen, MARUM Center for Marine Environmental SciencesBremen, Germany
| | - Solveig I Bühring
- University of Bremen, MARUM Center for Marine Environmental SciencesBremen, Germany
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127
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Feng RJ, Lin L, Li YY, Liu MH, Guo Y, Zhang Z. Effect of Ca 2+ to Sphingomyelin Investigated by Sum Frequency Generation Vibrational Spectroscopy. Biophys J 2017; 112:2173-2183. [PMID: 28538154 DOI: 10.1016/j.bpj.2017.04.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 04/06/2017] [Accepted: 04/17/2017] [Indexed: 10/19/2022] Open
Abstract
The interactions between Ca2+ ions and sphingomyelin play crucial roles in a wide range of cellular activities. However, little is known about the molecular details of the interactions at interfaces. In this work, we investigated the interactions between Ca2+ ions and egg sphingomyelin (ESM) Langmuir monolayers at the air/water interface by subwavenumber high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS). We show that Ca2+ ions can induce ordering of the acyl chains in the ESM monolayer. An analysis of the one alkyl-chain-deuterated ESM revealed that the Ca2+ ions do not affect the N-linked saturated fatty acid chain, although they make the sphingosine backbone become ordered. Further analysis of the SFG-VS spectra shows that the interactions between ESM and Ca2+ ions make the orientation of the methyl group at the end of sphingosine backbone change from pointing downward to pointing upward. Moreover, a large blue shift of the phosphate group at the CaCl2 solution interface indicates, to our knowledge, new cation binding modes. Such binding causes the phosphate moiety to dehydrate, resulting in the conformation change of the phosphate moiety. Based on these results, we propose the molecular mechanism that Ca2+ ions can bind to the phosphate group and subsequently destroy the intramolecular hydrogen bond between the 3-hydroxyl group and the phosphate oxygen, which results in an ordering change of the sphingosine backbone. These findings illustrate the potential application of HR-BB-SFG-VS to investigate lipid-cation interactions and the calcium channel modulated by lipid domain formation through slight structural changes in the membrane lipid. It will also shed light on the interactions of complex molecules at surfaces and interfaces.
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Affiliation(s)
- Rong-Juan Feng
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Lu Lin
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China; National Center for Nanoscience and Technology, Beijing, China
| | - Yi-Yi Li
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Ming-Hua Liu
- National Center for Nanoscience and Technology, Beijing, China; Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Yuan Guo
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Zhen Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
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128
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Simulations of Membrane-Disrupting Peptides I: Alamethicin Pore Stability and Spontaneous Insertion. Biophys J 2017; 111:1248-1257. [PMID: 27653483 DOI: 10.1016/j.bpj.2016.08.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 11/23/2022] Open
Abstract
An all-atom molecular dynamics simulation of the archetype barrel-stave alamethicin (alm) pore in a 1,2-dioleoyl-sn-glycero-3-phosphocholine bilayer at 313 K indicates that ∼7 μs is required for equilibration of a preformed 6-peptide pore; the pore remains stable for the duration of the remaining 7 μs of the trajectory, and the structure factors agree well with experiment. A 5 μs simulation of 10 surface-bound alm peptides shows significant peptide unfolding and some unbinding, but no insertion. Simulations at 363 and 413 K with a -0.2 V electric field yield peptide insertion in 1 μs. Insertion is initiated by the folding of residues 3-11 into an α-helix, and mediated by membrane water or by previously inserted peptides. The stability of five alm pore peptides at 413 K with a -0.2 V electric field demonstrates a significant preference for a transmembrane orientation. Hence, and in contrast to the cationic antimicrobial peptide described in the following article, alm shows a strong preference for the inserted over the surface-bound state.
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129
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Perrin BS, Fu R, Cotten ML, Pastor RW. Simulations of Membrane-Disrupting Peptides II: AMP Piscidin 1 Favors Surface Defects over Pores. Biophys J 2017; 111:1258-1266. [PMID: 27653484 DOI: 10.1016/j.bpj.2016.08.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 07/29/2016] [Accepted: 08/10/2016] [Indexed: 11/29/2022] Open
Abstract
Antimicrobial peptides (AMPs) that disrupt bacterial membranes are promising therapeutics against the growing number of antibiotic-resistant bacteria. The mechanism of membrane disruption by the AMP piscidin 1 was examined with multimicrosecond all-atom molecular dynamics simulations and solid-state NMR spectroscopy. The primary simulation was initialized with 20 peptides in four barrel-stave pores in a fully hydrated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol bilayer. The four pores relaxed to toroidal by 200 ns, only one porelike structure containing two transmembrane helices remained at 26 μs, and none of the 18 peptides released to the surface reinserted to form pores. The simulation was repeated at 413 K with an applied electric field and all peptides were surface-bound by 200 ns. Trajectories of surface-bound piscidin with and without applied fields at 313 and 413 K and totaling 6 μs show transient distortions of the bilayer/water interface (consistent with (31)P NMR), but no insertion to transmembrane or pore states. (15)N chemical shifts confirm a fully surface-bound conformation. Taken together, the simulation and experimental results imply that transient defects rather than stable pores are responsible for membrane disruption by piscidin 1, and likely other AMPs.
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Affiliation(s)
- B Scott Perrin
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Riqiang Fu
- National High Magnetic Field Laboratory, Tallahassee, Florida
| | - Myriam L Cotten
- Department of Applied Science, The College of William & Mary, Williamsburg, Virginia
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland.
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130
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Shirota K, Yagi K, Inaba T, Li PC, Murata M, Sugita Y, Kobayashi T. Detection of Sphingomyelin Clusters by Raman Spectroscopy. Biophys J 2017; 111:999-1007. [PMID: 27602727 DOI: 10.1016/j.bpj.2016.07.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 07/21/2016] [Accepted: 07/22/2016] [Indexed: 01/23/2023] Open
Abstract
Sphingomyelin (SM) is a major sphingolipid in mammalian cells that forms specific lipid domains in combination with cholesterol (Chol). Using molecular-dynamics simulation and density functional theory calculation, we identified a characteristic Raman band of SM at ∼1643 cm(-1) as amide I of the SM cluster. Experimental results indicate that this band is sensitive to the hydration of SM and the presence of Chol. We showed that this amide I Raman band can be utilized to examine the membrane distribution of SM. Similarly to SM, ceramide phosphoethanolamine (CerPE) exhibited an amide I Raman band in almost the same region, although CerPE lacks three methyl groups in the phosphocholine moiety of SM. In contrast to SM, the amide I band of CerPE was not affected by Chol, suggesting the importance of the methyl groups of SM in the SM-Chol interaction.
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Affiliation(s)
| | - Kiyoshi Yagi
- Theoretical Molecular Science Laboratory, RIKEN, Saitama, Japan
| | | | - Pai-Chi Li
- Theoretical Molecular Science Laboratory, RIKEN, Saitama, Japan
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, Osaka, Japan; Lipid Active Structure Project, Japan Science and Technology Agency, ERATO, Osaka, Japan
| | - Yuji Sugita
- Theoretical Molecular Science Laboratory, RIKEN, Saitama, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, Saitama, Japan; UMR 7213 CNRS, University of Strasbourg, Illkirch, France.
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131
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Patel DS, Park S, Wu EL, Yeom MS, Widmalm G, Klauda JB, Im W. Influence of Ganglioside GM1 Concentration on Lipid Clustering and Membrane Properties and Curvature. Biophys J 2017; 111:1987-1999. [PMID: 27806280 DOI: 10.1016/j.bpj.2016.09.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/18/2016] [Accepted: 09/19/2016] [Indexed: 10/20/2022] Open
Abstract
Gangliosides are a class of glycosphingolipids (GSLs) with amphiphilic character that are found at the outer leaflet of the cell membranes, where their ability to organize into special domains makes them vital cell membrane components. However, a molecular understanding of GSL-rich membranes in terms of their clustered organization, stability, and dynamics is still elusive. To gain molecular insight into the organization and dynamics of GSL-rich membranes, we performed all-atom molecular-dynamics simulations of bicomponent ganglioside GM1 in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) phospholipid bilayers with varying concentrations of GM1 (10%, 20%, and 30%). Overall, the simulations show very good agreement with available experimental data, including x-ray electron density profiles along the membrane normal, NMR carbohydrate proton-proton distances, and x-ray crystal structures. This validates the quality of our model systems for investigating GM1 clustering through an ordered-lipid-cluster analysis. The increase in GM1 concentration induces tighter lipid packing, driven mainly by inter-GM1 carbohydrate-carbohydrate interactions, leading to a greater preference for the positive curvature of GM1-containing membranes and larger cluster sizes of ordered-lipid clusters (with a composite of GM1 and POPC). These clusters tend to segregate and form a large percolated cluster at a 30% GM1 concentration at 293 K. At a higher temperature of 330 K, however, the segregation is not maintained.
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Affiliation(s)
- Dhilon S Patel
- Department of Biological Sciences and Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania
| | - Soohyung Park
- Department of Biological Sciences and Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania
| | - Emilia L Wu
- Department of Biological Sciences and Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania
| | - Min Sun Yeom
- Korean Institute of Science and Technology Information, Daejeon, Korea
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland; Biophysics Program, University of Maryland, College Park, Maryland.
| | - Wonpil Im
- Department of Biological Sciences and Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania.
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132
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Bandara A, Panahi A, Pantelopulos GA, Straub JE. Exploring the structure and stability of cholesterol dimer formation in multicomponent lipid bilayers. J Comput Chem 2017; 38:1479-1488. [PMID: 27761918 PMCID: PMC5398962 DOI: 10.1002/jcc.24516] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/27/2016] [Accepted: 09/30/2016] [Indexed: 01/13/2023]
Abstract
For 40 years, the existence and possible functional importance of cholesterol dimer formation has been discussed. Due to challenges associated with structural studies of membrane lipids, there has as yet been no direct experimental verification of the existence and relevance of the cholesterol dimer. Building on recent advances in lipid force fields for molecular simulation, in this work the structure and stability of the cholesterol dimer is characterized in POPC bilayers in absence and presence of sphingomyelin. The cholesterol dimer structural ensemble is found to consist of sub-states that reflect, but also differ from, previously proposed dimer structures. While face-to-face dimer structures predominate, no evidence is found for the existence of tail-to-tail dimers in POPC lipid bilayers. Near stoichiometric complex formation of cholesterol with sphingomyelin is found to effect cholesterol dimer structure without impacting population. Comparison with NMR-derived order parameters provide validation for the simulation model employed and conclusions drawn related to the structure and stability of cholesterol dimers in multicomponent lipid bilayers. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Asanga Bandara
- Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, Massachusetts, 02215, United States
| | - Afra Panahi
- Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, Massachusetts, 02215, United States
| | - George A. Pantelopulos
- Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, Massachusetts, 02215, United States
| | - John E. Straub
- Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, Massachusetts, 02215, United States
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133
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Thomsen B, Kawakami T, Shigemoto I, Sugita Y, Yagi K. Weight-Averaged Anharmonic Vibrational Analysis of Hydration Structures of Polyamide 6. J Phys Chem B 2017; 121:6050-6063. [DOI: 10.1021/acs.jpcb.7b00372] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bo Thomsen
- Theoretical
Molecular Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Tomonori Kawakami
- Advanced
Materials Research Laboratories, Toray Industries, Inc., 2-1 Sonoyama 3-chome, Otsu, Shiga 520-0842, Japan
| | - Isamu Shigemoto
- Advanced
Materials Research Laboratories, Toray Industries, Inc., 2-1 Sonoyama 3-chome, Otsu, Shiga 520-0842, Japan
| | - Yuji Sugita
- Theoretical
Molecular Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- RIKEN iTHES, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- RIKEN Advanced Institute for Computational Science, 7-1-26 Minatojima-Minamimachi,
Chuo-ku, Kobe, Hyogo 650-0047, Japan
- RIKEN Quantitative Biology Center, 6-7-1 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Kiyoshi Yagi
- Theoretical
Molecular Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- RIKEN iTHES, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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134
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Bera I, Klauda JB. Molecular Simulations of Mixed Lipid Bilayers with Sphingomyelin, Glycerophospholipids, and Cholesterol. J Phys Chem B 2017; 121:5197-5208. [DOI: 10.1021/acs.jpcb.7b00359] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Indrani Bera
- Department
of Chemical and Biomolecular Engineering and ‡Biophysics Program, University of Maryland, College Park, Maryland 20742, United States
| | - Jeffery B. Klauda
- Department
of Chemical and Biomolecular Engineering and ‡Biophysics Program, University of Maryland, College Park, Maryland 20742, United States
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135
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Wang E, Klauda JB. Examination of Mixtures Containing Sphingomyelin and Cholesterol by Molecular Dynamics Simulations. J Phys Chem B 2017; 121:4833-4844. [DOI: 10.1021/acs.jpcb.7b01832] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Eric Wang
- Department
of Chemical and Biomolecular Engineering and ‡Biophysics Graduate Program, University of Maryland, College Park, Maryland 20742, United States
| | - Jeffery B. Klauda
- Department
of Chemical and Biomolecular Engineering and ‡Biophysics Graduate Program, University of Maryland, College Park, Maryland 20742, United States
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136
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Edler E, Schulze E, Stein M. Membrane localization and dynamics of geranylgeranylated Rab5 hypervariable region. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1335-1349. [PMID: 28455099 DOI: 10.1016/j.bbamem.2017.04.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/18/2017] [Accepted: 04/23/2017] [Indexed: 12/11/2022]
Abstract
The small GTPase Rab5 is a key regulator of endosomal trafficking processes and a marker for the early endosome. The C-terminal hypervariable region (HVR) of Rab5 is post-translationally modified at residues Cys212 and Cys213 to accommodate two geranylgeranyl anchors (C20 carbon chain length) in order to associate Rab5 with the membrane. The structural role of the HVR regarding protein-early endosome membrane recruitment is not resolved due to its high degree of flexibility and lack of crystallographic information. Here, full-atomistic and coarse-grained molecular dynamics simulations of the truncated Rab5 HVR206-215 in three model membranes of increasing complexity (pure phospholipid bilayer, ternary membrane with cholesterol, six-component early endosome) were performed. Specific electrostatic interactions between the HVR206-215 Arg209 residue and the phosphate group of the inositol ring of PI(3)P were detected. This shows that PI(3)P acts as a first contact site of protein recruitment to the early endosome. The free energy change of HVR206-215 extraction from the bilayer was largest for the physiological negatively charged membrane. 5μs coarse-grained simulations revealed an active recruitment of PI(3)P to the HVR206-215 supporting the formation of Rab5- and PI(3)P enriched signaling platforms.
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Affiliation(s)
- Eileen Edler
- Molecular Simulations and Design Group, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Eric Schulze
- Molecular Simulations and Design Group, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany; International Max Planck Research School (IMPRS) for Advanced Methods in Process and Systems Engineering, Magdeburg, Germany
| | - Matthias Stein
- Molecular Simulations and Design Group, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany.
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137
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Galimzyanov TR, Lyushnyak AS, Aleksandrova VV, Shilova LA, Mikhalyov II, Molotkovskaya IM, Akimov SA, Batishchev OV. Line Activity of Ganglioside GM1 Regulates the Raft Size Distribution in a Cholesterol-Dependent Manner. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3517-3524. [PMID: 28324651 DOI: 10.1021/acs.langmuir.7b00404] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Liquid-ordered lipid domains, also called rafts, are assumed to be important players in different cellular processes, mainly signal transduction and membrane trafficking. They are thicker than the disordered part of the membrane and are thought to form to compensate for the hydrophobic mismatch between transmembrane proteins and the lipid environment. Despite the existence of such structures in vivo still being an open question, they are observed in model systems of multicomponent lipid bilayers. Moreover, the predictions obtained from model experiments allow the explanation of different physiological processes possibly involving rafts. Here we present the results of the study of the regulation of raft size distribution by ganglioside GM1. Combining atomic force microscopy with theoretical considerations based on the theory of membrane elasticity, we predict that this glycolipid should change the line tension of raft boundaries in two different ways, mainly depending on the cholesterol content. These results explain the shedding of gangliosides from the surface of tumor cells and the following ganglioside-induced apoptosis of T-lymphocytes in a raft-dependent manner. Moreover, the generality of the model allows the prediction of the line activity of different membrane components based on their molecular geometry.
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Affiliation(s)
- T R Galimzyanov
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences , 31/4 Leninskii Prospekt, Moscow, 119071 Russia
- National University of Science and Technology "MISiS" , 4 Leninskii Prospekt, Moscow, 119049 Russia
| | - A S Lyushnyak
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences , 31/4 Leninskii Prospekt, Moscow, 119071 Russia
- Moscow Institute of Physics and Technology , 9 Institutskii per., Dolgoprudnyi, Moscow Region, 141700 Russia
| | - V V Aleksandrova
- National University of Science and Technology "MISiS" , 4 Leninskii Prospekt, Moscow, 119049 Russia
| | - L A Shilova
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences , 31/4 Leninskii Prospekt, Moscow, 119071 Russia
- Moscow Institute of Physics and Technology , 9 Institutskii per., Dolgoprudnyi, Moscow Region, 141700 Russia
| | - I I Mikhalyov
- M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences , 16/10 Miklukho-Maklaya Str., Moscow, 117997 Russia
| | - I M Molotkovskaya
- M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences , 16/10 Miklukho-Maklaya Str., Moscow, 117997 Russia
| | - S A Akimov
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences , 31/4 Leninskii Prospekt, Moscow, 119071 Russia
- National University of Science and Technology "MISiS" , 4 Leninskii Prospekt, Moscow, 119049 Russia
| | - O V Batishchev
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences , 31/4 Leninskii Prospekt, Moscow, 119071 Russia
- Moscow Institute of Physics and Technology , 9 Institutskii per., Dolgoprudnyi, Moscow Region, 141700 Russia
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138
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Structural insights into adiponectin receptors suggest ceramidase activity. Nature 2017; 544:120-123. [PMID: 28329765 DOI: 10.1038/nature21714] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 02/21/2017] [Indexed: 02/07/2023]
Abstract
Adiponectin receptors (ADIPORs) are integral membrane proteins that control glucose and lipid metabolism by mediating, at least in part, a cellular ceramidase activity that catalyses the hydrolysis of ceramide to produce sphingosine and a free fatty acid (FFA). The crystal structures of the two receptor subtypes, ADIPOR1 and ADIPOR2, show a similar overall seven-transmembrane-domain architecture with large unoccupied cavities and a zinc binding site within the seven transmembrane domain. However, the molecular mechanisms by which ADIPORs function are not known. Here we describe the crystal structure of ADIPOR2 bound to a FFA molecule and show that ADIPOR2 possesses intrinsic basal ceramidase activity that is enhanced by adiponectin. We also identify a ceramide binding pose and propose a possible mechanism for the hydrolytic activity of ADIPOR2 using computational approaches. In molecular dynamics simulations, the side chains of residues coordinating the zinc rearrange quickly to promote the nucleophilic attack of a zinc-bound hydroxide ion onto the ceramide amide carbonyl. Furthermore, we present a revised ADIPOR1 crystal structure exhibiting a seven-transmembrane-domain architecture that is clearly distinct from that of ADIPOR2. In this structure, no FFA is observed and the ceramide binding pocket and putative zinc catalytic site are exposed to the inner membrane leaflet. ADIPOR1 also possesses intrinsic ceramidase activity, so we suspect that the two distinct structures may represent key steps in the enzymatic activity of ADIPORs. The ceramidase activity is low, however, and further studies will be required to characterize fully the enzymatic parameters and substrate specificity of ADIPORs. These insights into ADIPOR function will enable the structure-based design of potent modulators of these clinically relevant enzymes.
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139
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Edler E, Stein M. Probing the druggability of membrane-bound Rab5 by molecular dynamics simulations. J Enzyme Inhib Med Chem 2017; 32:434-443. [PMID: 28090783 PMCID: PMC6010109 DOI: 10.1080/14756366.2016.1260564] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Rab5 is a small GTPase and a key regulator in early endosomal trafficking. Rab5 and its effectors are involved in a large number of infectious diseases and certain types of cancer. We performed µs atomistic molecular dynamics simulations of inactive and active full-length Rab5 anchored to a complex model bilayer with composition of the early endosome membrane. Direct interactions between the Rab5 G domain and the bilayer were observed. We found two dominant nucleotide-dependent orientations characterised by a different accessibility of the switch regions. The “buried switch” orientation was mainly associated with inactive Rab5 accompanied with a rather extended structure of the hypervariable C-terminal region. Active Rab5 preferred an orientation in which the switch regions are accessible to effector proteins. These structural differences may provide an opportunity to selectively target one Rab5 state and lead to new approaches in the development of Rab5-specific therapies.
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Affiliation(s)
- Eileen Edler
- a Molecular Simulations and Design Group , Max Planck Institute for Dynamics of Complex Technical Systems , Magdeburg , Germany
| | - Matthias Stein
- a Molecular Simulations and Design Group , Max Planck Institute for Dynamics of Complex Technical Systems , Magdeburg , Germany
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140
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Herzog FA, Braun L, Schoen I, Vogel V. Structural Insights How PIP2 Imposes Preferred Binding Orientations of FAK at Lipid Membranes. J Phys Chem B 2017; 121:3523-3535. [DOI: 10.1021/acs.jpcb.6b09349] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Florian A. Herzog
- Laboratory of Applied
Mechanobiology,
Department of Health Sciences and Technology, ETH Zürich, 8093 Zürich, Switzerland
| | - Lukas Braun
- Laboratory of Applied
Mechanobiology,
Department of Health Sciences and Technology, ETH Zürich, 8093 Zürich, Switzerland
| | - Ingmar Schoen
- Laboratory of Applied
Mechanobiology,
Department of Health Sciences and Technology, ETH Zürich, 8093 Zürich, Switzerland
| | - Viola Vogel
- Laboratory of Applied
Mechanobiology,
Department of Health Sciences and Technology, ETH Zürich, 8093 Zürich, Switzerland
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141
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Dickson CJ, Hornak V, Pearlstein RA, Duca JS. Structure–Kinetic Relationships of Passive Membrane Permeation from Multiscale Modeling. J Am Chem Soc 2016; 139:442-452. [DOI: 10.1021/jacs.6b11215] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Callum J. Dickson
- Computer-Aided Drug Discovery,
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Viktor Hornak
- Computer-Aided Drug Discovery,
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Robert A. Pearlstein
- Computer-Aided Drug Discovery,
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Jose S. Duca
- Computer-Aided Drug Discovery,
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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142
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Andoh Y, Aoki N, Okazaki S. Molecular dynamics study of lipid bilayers modeling the plasma membranes of mouse hepatocytes and hepatomas. J Chem Phys 2016; 144:085104. [PMID: 26931728 DOI: 10.1063/1.4942159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular dynamics (MD) calculations of lipid bilayers modeling the plasma membranes of normal mouse hepatocytes and hepatomas in water have been performed under physiological isothermal-isobaric conditions (310.15 K and 1 atm). The changes in the membrane properties induced by hepatic canceration were investigated and were compared with previous MD calculations included in our previous study of the changes in membrane properties induced by murine thymic canceration. The calculated model membranes for normal hepatocytes and hepatomas comprised 23 and 24 kinds of lipids, respectively. These included phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, sphingomyelin, lysophospholipids, and cholesterol. We referred to previously published experimental values for the mole fraction of the lipids adopted in the present calculations. The calculated structural and dynamic properties of the membranes such as lateral structure, order parameters, lateral self-diffusion constants, and rotational correlation times all showed that hepatic canceration causes plasma membranes to become more ordered laterally and less fluid. Interestingly, this finding contrasts with the less ordered structure and increased fluidity of plasma membranes induced by thymic canceration observed in our previous MD study.
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Affiliation(s)
- Yoshimichi Andoh
- Center of Computational Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Noriyuki Aoki
- Department of Applied Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Susumu Okazaki
- Center of Computational Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
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143
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Usman Mirza M, Rafique S, Ali A, Munir M, Ikram N, Manan A, Salo-Ahen OMH, Idrees M. Towards peptide vaccines against Zika virus: Immunoinformatics combined with molecular dynamics simulations to predict antigenic epitopes of Zika viral proteins. Sci Rep 2016; 6:37313. [PMID: 27934901 PMCID: PMC5146661 DOI: 10.1038/srep37313] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 10/27/2016] [Indexed: 12/16/2022] Open
Abstract
The recent outbreak of Zika virus (ZIKV) infection in Brazil has developed to a global health concern due to its likely association with birth defects (primary microcephaly) and neurological complications. Consequently, there is an urgent need to develop a vaccine to prevent or a medicine to treat the infection. In this study, immunoinformatics approach was employed to predict antigenic epitopes of Zika viral proteins to aid in development of a peptide vaccine against ZIKV. Both linear and conformational B-cell epitopes as well as cytotoxic T-lymphocyte (CTL) epitopes were predicted for ZIKV Envelope (E), NS3 and NS5 proteins. We further investigated the binding interactions of altogether 15 antigenic CTL epitopes with three class I major histocompatibility complex (MHC I) proteins after docking the peptides to the binding groove of the MHC I proteins. The stability of the resulting peptide-MHC I complexes was further studied by molecular dynamics simulations. The simulation results highlight the limits of rigid-body docking methods. Some of the antigenic epitopes predicted and analyzed in this work might present a preliminary set of peptides for future vaccine development against ZIKV.
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Affiliation(s)
- Muhammad Usman Mirza
- Center for Research in Molecular Medicine (CRiMM), The University of Lahore, Pakistan
| | - Shazia Rafique
- Centre for Applied Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Amjad Ali
- Centre for Applied Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Mobeen Munir
- Division of Science and Technology, University of Education Lahore, Pakistan
| | - Nazia Ikram
- Institute of Molecular Biology and Biotechnology (IMBB), The University of Lahore, Pakistan
| | - Abdul Manan
- Institute of Molecular Biology and Biotechnology (IMBB), The University of Lahore, Pakistan
| | - Outi M. H. Salo-Ahen
- Structural Bioinformatics Laboratory, Faculty of Science and Engineering, Biochemistry, Åbo Akademi University, Turku, Finland
- Pharmaceutical Sciences Laboratory, Faculty of Science and Engineering, Pharmacy, Åbo Akademi University, Turku, Finland
| | - Muhammad Idrees
- Centre for Applied Molecular Biology, University of the Punjab, Lahore, Pakistan
- Vice Chancellor Hazara University, Mansehra, Pakistan
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144
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Yasuda T, Al Sazzad MA, Jäntti NZ, Pentikäinen OT, Slotte JP. The Influence of Hydrogen Bonding on Sphingomyelin/Colipid Interactions in Bilayer Membranes. Biophys J 2016; 110:431-440. [PMID: 26789766 DOI: 10.1016/j.bpj.2015.11.3515] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 11/17/2015] [Accepted: 11/30/2015] [Indexed: 12/23/2022] Open
Abstract
The phospholipid acyl chain composition and order, the hydrogen bonding, and properties of the phospholipid headgroup all influence cholesterol/phospholipid interactions in hydrated bilayers. In this study, we examined the influence of hydrogen bonding on sphingomyelin (SM) colipid interactions in fluid uni- and multilamellar vesicles. We have compared the properties of oleoyl or palmitoyl SM with comparable dihydro-SMs, because the hydrogen bonding properties of SM and dihydro-SM differ. The association of cholestatrienol, a fluorescent cholesterol analog, with oleoyl sphingomyelin (OSM) was significantly stronger than its association with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, in bilayers with equal acyl chain order. The association of cholestatrienol with dihydro-OSM, which lacks a trans double bond in the sphingoid base, was even stronger than the association with OSM, suggesting an important role for hydrogen bonding in stabilizing sterol/SM interactions. Furthermore, with saturated SM in the presence of 15 mol % cholesterol, cholesterol association with fluid dihydro-palmitoyl SM bilayers was stronger than seen with palmitoyl SM under similar conditions. The different hydrogen bonding properties in OSM and dihydro-OSM bilayers also influenced the segregation of palmitoyl ceramide and dipalmitoylglycerol into an ordered phase. The ordered, palmitoyl ceramide-rich phase started to form above 2 mol % in the dihydro-OSM bilayers but only above 6 mol % in the OSM bilayers. The lateral segregation of dipalmitoylglycerol was also much more pronounced in dihydro-OSM bilayers than in OSM bilayers. The results show that hydrogen bonding is important for sterol/SM and ceramide/SM interactions, as well as for the lateral segregation of a diglyceride. A possible molecular explanation for the different hydrogen bonding in SM and dihydro-SM bilayers is presented and discussed.
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Affiliation(s)
- Tomokazu Yasuda
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Md Abdullah Al Sazzad
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Niklas Z Jäntti
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Olli T Pentikäinen
- Computational Bioscience Laboratory, Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland.
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145
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Vogel A, Scheidt HA, Baek DJ, Bittman R, Huster D. Structure and dynamics of the aliphatic cholesterol side chain in membranes as studied by (2)H NMR spectroscopy and molecular dynamics simulation. Phys Chem Chem Phys 2016; 18:3730-8. [PMID: 26762541 DOI: 10.1039/c5cp05084g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cholesterol is an evolutionarily highly optimized molecule particularly known for its ability to condense the phospholipids in cellular membranes. Until recently, the accompanying increase in the chain order of the surrounding phospholipids was attributed to the planar and rigid tetracyclic ring structure of cholesterol. However, detailed investigations of cholesterol's aliphatic side chain demonstrated that this side chain is responsible for approximately half of the condensation effect. Therefore, we investigated the structure and dynamics of the aliphatic side chain of cholesterol using (2)H solid-state nuclear magnetic resonance (NMR) spectroscopy and microsecond timescale all-atom molecular dynamics (MD) simulations in four different model membranes: POPC, DPPC, PSM, and POPC/PSM (1 : 1 mol/mol) and at three different temperatures: 5 °C, 37 °C, and 50 °C. A cholesterol variant, in which 11 hydrogens of the aliphatic side chain were exchanged for deuterium, was used and the respective (2)H NMR spectra confirmed the axially asymmetric rotational diffusion of cholesterol in DPPC and PSM. Furthermore, NMR spectra indicated that some hydrogens showed an unexpected magnetic inequivalency. This finding was confirmed by all-atom molecular dynamics simulations and detailed analysis revealed that the hydrogens of the methylene groups at C22, C23, and C24 are magnetically inequivalent. This inequivalency is caused by steric clashes of the aliphatic side chain with the ring structure of cholesterol as well as the branched C21 methyl group. These excluded volume effects result in reduced conformational flexibility of the aliphatic side chain of cholesterol and explain its high order (order parameter of 0.78 for chain motions) and large contribution to the condensation effect. Additionally, the motional pattern of the side chain becomes highly anisotropic such that it shows larger fluctuations perpendicular to the ring plane of cholesterol with a biaxiality of the distribution of 0.046. Overall, our results shed light on the mechanism how the aliphatic side chain is able to contribute about half of the condensation effect of cholesterol.
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Affiliation(s)
- Alexander Vogel
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, 04275 Leipzig, Germany.
| | - Holger A Scheidt
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, 04275 Leipzig, Germany.
| | - Dong Jae Baek
- College of Pharmacy and Natural Medicine Research Institute, Mokpo National University, Jeonnam, Republic of Korea and Department of Chemistry and Biochemistry, Queens College of the City University of New York, Flushing, NY 11367-1597, USA
| | - Robert Bittman
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, Flushing, NY 11367-1597, USA
| | - Daniel Huster
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, 04275 Leipzig, Germany.
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146
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Sodt A, Venable R, Lyman E, Pastor R. Nonadditive Compositional Curvature Energetics of Lipid Bilayers. PHYSICAL REVIEW LETTERS 2016; 117:138104. [PMID: 27715135 PMCID: PMC5134905 DOI: 10.1103/physrevlett.117.138104] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Indexed: 05/26/2023]
Abstract
The unique properties of the individual lipids that compose biological membranes together determine the energetics of the surface. The energetics of the surface, in turn, govern the formation of membrane structures and membrane reshaping processes, and thus they will underlie cellular-scale models of viral fusion, vesicle-dependent transport, and lateral organization relevant to signaling. The spontaneous curvature, to the best of our knowledge, is always assumed to be additive. We describe observations from simulations of unexpected nonadditive compositional curvature energetics of two lipids essential to the plasma membrane: sphingomyelin and cholesterol. A model is developed that connects molecular interactions to curvature stress, and which explains the role of local composition. Cholesterol is shown to lower the number of effective Kuhn segments of saturated acyl chains, reducing lateral pressure below the neutral surface of bending and favoring positive curvature. The effect is not observed for unsaturated (flexible) acyl chains. Likewise, hydrogen bonding between sphingomyelin lipids leads to positive curvature, but only at sufficient concentration, below which the lipid prefers negative curvature.
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Affiliation(s)
- A.J. Sodt
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - R.M. Venable
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - E. Lyman
- Department of Physics and Astronomy; Department of Chemistry and Biochemistry, University of Delaware, Newark, DE
| | - R.W. Pastor
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
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147
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An extensive simulation study of lipid bilayer properties with different head groups, acyl chain lengths, and chain saturations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:3093-3104. [PMID: 27664502 DOI: 10.1016/j.bbamem.2016.09.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/14/2016] [Accepted: 09/19/2016] [Indexed: 12/21/2022]
Abstract
Previous MD simulations of six phosphocholine (PC) lipid bilayers demonstrated the accuracy of the CHARMM36 force field (C36FF) for PC bilayer simulation at varied temperatures (BBA-Biomembranes, 1838 (2014): 2520-2529). In this work, we further examine the accuracy of C36FF over a wide temperature range for a broader range of lipid types such as various head groups (phosphatidic acid (PA), PC, phosphoethanolamine (PE), phosphoglycerol (PG), and phosphoserine (PS)), and tails (saturated, mono-, mixed- and poly-unsaturated acyl chains with varied chain lengths). The structural properties (surface area per lipid (SA/lip), overall bilayer thickness, hydrophobic thickness, headgroup-to-headgroup thickness, deuterium order parameter (SCD), and spin-lattice relaxation time (T1)) obtained from simulations agree well with nearly all available experimental data. Our analyses indicate that PS lipids have the most inter-lipid hydrogen bonds, while PG lipids have the most intra-lipid hydrogen bonds, which play the main role in their low SA/lip in PS lipids and low thicknesses in PG lipids, respectively. PS, PE, and PA lipids have the largest contact clusters with on average 5-8 lipids per cluster, while PC and PG have clusters of 4 lipids based on a cutoff distance of 6.5Å. PS lipids have much slower lipid wobble (i.e., higher correlation time) than other head groups at a given temperature as the hydrogen bonded network significantly reduces a lipid's mobility, and the rate of lipid wobble increases dramatically as temperature increases. These in-depth analyses facilitate further understanding of lipid bilayers at the atomic level.
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148
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Wu EL, Qi Y, Park S, Mallajosyula SS, MacKerell AD, Klauda JB, Im W. Insight into Early-Stage Unfolding of GPI-Anchored Human Prion Protein. Biophys J 2016; 109:2090-100. [PMID: 26588568 DOI: 10.1016/j.bpj.2015.10.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/04/2015] [Accepted: 10/08/2015] [Indexed: 11/29/2022] Open
Abstract
Prion diseases are fatal neurodegenerative disorders, which are characterized by the accumulation of misfolded prion protein (PrPSc) converted from a normal host cellular prion protein (PrPC). Experimental studies suggest that PrPC is enriched with α-helical structure, whereas PrPSc contains a high proportion of β-sheet. In this study, we report the impact of N-glycosylation and the membrane on the secondary structure stability utilizing extensive microsecond molecular dynamics simulations. Our results reveal that the HB (residues 173 to 194) C-terminal fragment undergoes conformational changes and helix unfolding in the absence of membrane environments because of the competition between protein backbone intramolecular and protein-water intermolecular hydrogen bonds as well as its intrinsic instability originated from the amino acid sequence. This initiation of the unfolding process of PrPC leads to a subsequent increase in the length of the HB-HC loop (residues 195 to 199) that may trigger larger rigid body motions or further unfolding around this region. Continuous interactions between prion protein and the membrane not only constrain the protein conformation but also decrease the solvent accessibility of the backbone atoms, thereby stabilizing the secondary structure, which is enhanced by N-glycosylation via additional interactions between the N-glycans and the membrane surface.
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Affiliation(s)
- Emilia L Wu
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, Kansas
| | - Yifei Qi
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, Kansas
| | - Soohyung Park
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, Lawrence, Kansas
| | - Sairam S Mallajosyula
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland; Department of Chemistry, Indian Institute of Technology Gandhinagar, Chandkheda, Ahmedabad, Gujarat, India
| | - Alexander D MacKerell
- Department of Chemistry, Indian Institute of Technology Gandhinagar, Chandkheda, Ahmedabad, Gujarat, India
| | - 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 Bioinformatics, The University of Kansas, Lawrence, Kansas.
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149
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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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150
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Yagi K, Li PC, Shirota K, Kobayashi T, Sugita Y. A weight averaged approach for predicting amide vibrational bands of a sphingomyelin bilayer. Phys Chem Chem Phys 2016; 17:29113-23. [PMID: 26460816 DOI: 10.1039/c5cp04131g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Infrared (IR) and Raman spectra of a sphingomyelin (SM) bilayer have been calculated for the amide I, II and A modes and the double-bonded CC stretching mode by a weight averaged approach, based on an all-atom molecular dynamics (MD) simulation and a vibrational structure calculation. Representative structures and statistical weights of SM clusters connected by hydrogen bonds (HBs) are observed in MD trajectories. After constructing smaller fragments from the SM clusters, the vibrational spectra of the target modes were calculated by normal mode analysis with a correction for anharmonicity, using density functional theory. The final IR and Raman spectra of a SM bilayer were obtained as the weight averages over all SM clusters. The calculated Raman spectrum is in excellent agreement with a recent measurement, providing a clear assignment of the peak in question observed at 1643 cm(-1) to the amide I modes of a SM bilayer. The analysis of the IR spectrum has also revealed that the amide bands are sensitive to the water content inside the membrane, since their band positions are strongly modulated by the HB between SM and water molecules. The present study suggests that the amide I band serves as a marker to identify the formation of SM clusters, and opens a new way to detect lipid rafts in the biological membrane.
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Affiliation(s)
- Kiyoshi Yagi
- RIKEN Theoretical Molecular Science Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. and RIKEN iTHES, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Pai-Chi Li
- RIKEN Theoretical Molecular Science Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Koichiro Shirota
- RIKEN Lipid Biology Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Toshihide Kobayashi
- RIKEN Lipid Biology Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan and INSERM, Villeurbanne, France
| | - Yuji Sugita
- RIKEN Theoretical Molecular Science Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. and RIKEN iTHES, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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