251
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de Meyer FJM, Rodgers JM, Willems TF, Smit B. Molecular simulation of the effect of cholesterol on lipid-mediated protein-protein interactions. Biophys J 2011; 99:3629-38. [PMID: 21112287 DOI: 10.1016/j.bpj.2010.09.030] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 09/14/2010] [Accepted: 09/16/2010] [Indexed: 12/01/2022] Open
Abstract
Experiments and molecular simulations have shown that the hydrophobic mismatch between proteins and membranes contributes significantly to lipid-mediated protein-protein interactions. In this article, we discuss the effect of cholesterol on lipid-mediated protein-protein interactions as function of hydrophobic mismatch, protein diameter and protein cluster size, lipid tail length, and temperature. To do so, we study a mesoscopic model of a hydrated bilayer containing lipids and cholesterol in which proteins are embedded, with a hybrid dissipative particle dynamics-Monte Carlo method. We propose a mechanism by which cholesterol affects protein interactions: protein-induced, cholesterol-enriched, or cholesterol-depleted lipid shells surrounding the proteins affect the lipid-mediated protein-protein interactions. Our calculations of the potential of mean force between proteins and protein clusters show that the addition of cholesterol dramatically reduces repulsive lipid-mediated interactions between proteins (protein clusters) with positive mismatch, but does not affect attractive interactions between proteins with negative mismatch. Cholesterol has only a modest effect on the repulsive interactions between proteins with different mismatch.
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Affiliation(s)
- Frédérick J-M de Meyer
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California, USA.
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252
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Tumaneng PW, Pandit SA, Zhao G, Scott HL. Self-consistent mean-field model for palmitoyloleoylphosphatidylcholine-palmitoyl sphingomyelin-cholesterol lipid bilayers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:031925. [PMID: 21517541 PMCID: PMC3397247 DOI: 10.1103/physreve.83.031925] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 01/13/2011] [Indexed: 05/30/2023]
Abstract
The connection between membrane inhomogeneity and the structural basis of lipid rafts has sparked interest in the lateral organization of model lipid bilayers of two and three components. In an effort to investigate anisotropic lipid distribution in mixed bilayers, a self-consistent mean-field theoretical model is applied to palmitoyloleoylphosphatidylcholine (POPC)--palmitoyl sphingomyelin (PSM)--cholesterol mixtures. The compositional dependence of lateral organization in these mixtures is mapped onto a ternary plot. The model utilizes molecular dynamics simulations to estimate interaction parameters and to construct chain conformation libraries. We find that at some concentration ratios the bilayers separate spatially into regions of higher and lower chain order coinciding with areas enriched with PSM and POPC, respectively. To examine the effect of the asymmetric chain structure of POPC on bilayer lateral inhomogeneity, we consider POPC-lipid interactions with and without angular dependence. Results are compared with experimental data and with results from a similar model for mixtures of dioleoylphosphatidylcholine, steroyl sphingomyelin, and cholesterol.
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Affiliation(s)
- Paul W Tumaneng
- Department of Biological, Chemical and Physical Sciences and Center for the Molecular Study of Condensed Soft Matter, Illinois Institute of Technology, Chicago, Illinois 60616, USA
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253
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de Joannis J, Coppock PS, Yin F, Mori M, Zamorano A, Kindt JT. Atomistic Simulation of Cholesterol Effects on Miscibility of Saturated and Unsaturated Phospholipids: Implications for Liquid-Ordered/Liquid-Disordered Phase Coexistence. J Am Chem Soc 2011; 133:3625-34. [DOI: 10.1021/ja110425s] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jason de Joannis
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
- Institutional Program of Molecular Biomedicine, ENMH-IPN, Mexico City, Mexico
| | - Patrick S. Coppock
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
- Institutional Program of Molecular Biomedicine, ENMH-IPN, Mexico City, Mexico
| | - Fuchang Yin
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
- Institutional Program of Molecular Biomedicine, ENMH-IPN, Mexico City, Mexico
| | - Makoto Mori
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
- Institutional Program of Molecular Biomedicine, ENMH-IPN, Mexico City, Mexico
| | - Absalom Zamorano
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
- Institutional Program of Molecular Biomedicine, ENMH-IPN, Mexico City, Mexico
| | - James T. Kindt
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
- Institutional Program of Molecular Biomedicine, ENMH-IPN, Mexico City, Mexico
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254
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Chrast R, Saher G, Nave KA, Verheijen MHG. Lipid metabolism in myelinating glial cells: lessons from human inherited disorders and mouse models. J Lipid Res 2010; 52:419-34. [PMID: 21062955 DOI: 10.1194/jlr.r009761] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The integrity of central and peripheral nervous system myelin is affected in numerous lipid metabolism disorders. This vulnerability was so far mostly attributed to the extraordinarily high level of lipid synthesis that is required for the formation of myelin, and to the relative autonomy in lipid synthesis of myelinating glial cells because of blood barriers shielding the nervous system from circulating lipids. Recent insights from analysis of inherited lipid disorders, especially those with prevailing lipid depletion and from mouse models with glia-specific disruption of lipid metabolism, shed new light on this issue. The particular lipid composition of myelin, the transport of lipid-associated myelin proteins, and the necessity for timely assembly of the myelin sheath all contribute to the observed vulnerability of myelin to perturbed lipid metabolism. Furthermore, the uptake of external lipids may also play a role in the formation of myelin membranes. In addition to an improved understanding of basic myelin biology, these data provide a foundation for future therapeutic interventions aiming at preserving glial cell integrity in metabolic disorders.
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Affiliation(s)
- Roman Chrast
- Department of Medical Genetics, University of Lausanne, Switzerland.
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255
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Gallová J, Uhríková D, Kučerka N, Teixeira J, Balgavý P. Partial area of cholesterol in monounsaturated diacylphosphatidylcholine bilayers. Chem Phys Lipids 2010; 163:765-70. [DOI: 10.1016/j.chemphyslip.2010.08.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 08/03/2010] [Accepted: 08/12/2010] [Indexed: 11/16/2022]
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256
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Gallová J, Uhríková D, Kučerka N, Doktorovová S, Funari SS, Teixeira J, Balgavý P. The effects of cholesterol and β-sitosterol on the structure of saturated diacylphosphatidylcholine bilayers. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2010; 40:153-63. [DOI: 10.1007/s00249-010-0635-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 09/29/2010] [Accepted: 09/30/2010] [Indexed: 11/24/2022]
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257
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Kučerka N, Marquardt D, Harroun TA, Nieh MP, Wassall SR, de Jong DH, Schäfer LV, Marrink SJ, Katsaras J. Cholesterol in Bilayers with PUFA Chains: Doping with DMPC or POPC Results in Sterol Reorientation and Membrane-Domain Formation. Biochemistry 2010; 49:7485-93. [DOI: 10.1021/bi100891z] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Norbert Kučerka
- Canadian Neutron Beam Centre, National Research Council, Chalk River, Ontario K0J 1J0, Canada
- Department of Physical Chemistry of Drugs, Comenius University, 835 35 Bratislava, Slovakia
| | - Drew Marquardt
- Department of Physics, Brock University, St. Catherines, Ontario L2S 3A1, Canada
| | - Thad A. Harroun
- Department of Physics, Brock University, St. Catherines, Ontario L2S 3A1, Canada
| | - Mu-Ping Nieh
- Canadian Neutron Beam Centre, National Research Council, Chalk River, Ontario K0J 1J0, Canada
| | - Stephen R. Wassall
- Department of Physics, Indiana University−Purdue University Indianapolis, Indianapolis, Indiana 46202
| | - Djurre H. de Jong
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Lars V. Schäfer
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Siewert J. Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - John Katsaras
- Canadian Neutron Beam Centre, National Research Council, Chalk River, Ontario K0J 1J0, Canada
- Guelph-Waterloo Physics Institute and Biophysics Interdepartmental Group and Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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258
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Lipid chain branching at the iso- and anteiso-positions in complex Chlamydia membranes: a molecular dynamics study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:323-31. [PMID: 20692231 DOI: 10.1016/j.bbamem.2010.07.036] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 07/28/2010] [Accepted: 07/29/2010] [Indexed: 11/22/2022]
Abstract
Membranes in the intracellular eubacterial parasite Chlamydia trachomatis consist of the elementary body (EB) and reticular body (RB), and contain methyl branches at the iso- and anteiso-positions for some phospholipid chains. Acyl chain branching is the focus of this study. Molecular dynamics simulations were used to study bilayers of 1-13-methylpentadecanoyl-2-palmitoyl-phosphatidylcholine (13-MpPPC), 1-14-methylpentadecanoyl-2-palmitoyl-phosphatidylcholine (14-MpPPC), and diphytanoylphosphatidylcholine (DPhPC). These three membranes were simulated at 323K and simulations of DPhPC at 298K were also performed for better comparison to existing experimental data. Two simulations of representative EB and RB membranes of C. trachomatis composed of nine different lipid components were performed at 310.15K, to accurately reflect compositions determined by experiment and physiological conditions. Based on nearly 0.5μs of simulation data, we report that branching increases average lipid surface area, area elastic moduli, and lipid axial relaxation times, while decreasing lipid chain order. Branching also has a distinct effect on electron density profiles. Due to their high cholesterol concentrations, the EB and RB membranes were found to have relatively high area elastic moduli, which may have important biological implications.
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259
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Tristram-Nagle S, Chan R, Kooijman E, Uppamoochikkal P, Qiang W, Weliky DP, Nagle JF. HIV fusion peptide penetrates, disorders, and softens T-cell membrane mimics. J Mol Biol 2010; 402:139-53. [PMID: 20655315 DOI: 10.1016/j.jmb.2010.07.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 07/12/2010] [Accepted: 07/13/2010] [Indexed: 02/01/2023]
Abstract
This work investigates the interaction of N-terminal gp41 fusion peptide (FP) of human immunodeficiency virus type 1 (HIV-1) with model membranes in order to elucidate how FP leads to fusion of HIV and T-cell membranes. FP constructs were (i) wild-type FP23 (23 N-terminal amino acids of gp41), (ii) water-soluble monomeric FP that adds six lysines on the C-terminus of FP23 (FPwsm), and (iii) the C-terminus covalently linked trimeric version (FPtri) of FPwsm. Model membranes were (i) LM3 (a T-cell mimic), (ii) 1,2-dioleoyl-sn-glycero-3-phosphocholine, (iii) 1,2-dioleoyl-sn-glycero-3-phosphocholine/30 mol% cholesterol, (iv) 1,2-dierucoyl-sn-glycero-3-phosphocholine, and (v) 1,2-dierucoyl-sn-glycero-3-phosphocholine/30 mol% cholesterol. Diffuse synchrotron low-angle x-ray scattering from fully hydrated samples, supplemented by volumetric data, showed that FP23 and FPtri penetrate into the hydrocarbon region and cause membranes to thin. Depth of penetration appears to depend upon a complex combination of factors including bilayer thickness, presence of cholesterol, and electrostatics. X-ray data showed an increase in curvature in hexagonal phase 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine, which further indicates that FP23 penetrates into the hydrocarbon region rather than residing in the interfacial headgroup region. Low-angle x-ray scattering data also yielded the bending modulus K(C), a measure of membrane stiffness, and wide-angle x-ray scattering yielded the S(xray) orientational order parameter. Both FP23 and FPtri decreased K(C) and S(xray) considerably, while the weak effect of FPwsm suggests that it did not partition strongly into LM3 model membranes. Our results are consistent with the HIV FP disordering and softening the T-cell membrane, thereby lowering the activation energy for viral membrane fusion.
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Affiliation(s)
- Stephanie Tristram-Nagle
- Biological Physics Group, Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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260
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Martinez-Seara H, Róg T, Karttunen M, Vattulainen I, Reigada R. Cholesterol induces specific spatial and orientational order in cholesterol/phospholipid membranes. PLoS One 2010; 5:e11162. [PMID: 20567600 PMCID: PMC2887443 DOI: 10.1371/journal.pone.0011162] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2010] [Accepted: 05/25/2010] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND In lipid bilayers, cholesterol facilitates the formation of the liquid-ordered phase and enables the formation of laterally ordered structures such as lipid rafts. While these domains have an important role in a variety of cellular processes, the precise atomic-level mechanisms responsible for cholesterol's specific ordering and packing capability have remained unresolved. METHODOLOGY/PRINCIPAL FINDINGS Our atomic-scale molecular dynamics simulations reveal that this ordering and the associated packing effects in membranes largely result from cholesterol's molecular structure, which differentiates cholesterol from other sterols. We find that cholesterol molecules prefer to be located in the second coordination shell, avoiding direct cholesterol-cholesterol contacts, and form a three-fold symmetric arrangement with proximal cholesterol molecules. At larger distances, the lateral three-fold organization is broken by thermal fluctuations. For other sterols having less structural asymmetry, the three-fold arrangement is considerably lost. CONCLUSIONS/SIGNIFICANCE We conclude that cholesterol molecules act collectively in lipid membranes. This is the main reason why the liquid-ordered phase only emerges for Chol concentrations well above 10 mol% where the collective self-organization of Chol molecules emerges spontaneously. The collective ordering process requires specific molecular-scale features that explain why different sterols have very different membrane ordering properties: the three-fold symmetry in the Chol-Chol organization arises from the cholesterol off-plane methyl groups allowing the identification of raft-promoting sterols from those that do not promote rafts.
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Affiliation(s)
- Hector Martinez-Seara
- Department of Physical Chemistry and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Barcelona, Spain
| | - Tomasz Róg
- Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Mikko Karttunen
- Department of Applied Mathematics, The University of Western Ontario, London, Ontario, Canada
| | - Ilpo Vattulainen
- Department of Physics, Tampere University of Technology, Tampere, Finland
- MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark
- Department of Applied Physics, Aalto University School of Science and Technology, Espoo, Finland
| | - Ramon Reigada
- Department of Physical Chemistry and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Barcelona, Spain
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261
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Tumaneng PW, Pandit SA, Zhao G, Scott HL. Lateral organization of complex lipid mixtures from multiscale modeling. J Chem Phys 2010; 132:065104. [PMID: 20151760 PMCID: PMC2833188 DOI: 10.1063/1.3314729] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 01/20/2010] [Indexed: 11/14/2022] Open
Abstract
The organizational properties of complex lipid mixtures can give rise to functionally important structures in cell membranes. In model membranes, ternary lipid-cholesterol (CHOL) mixtures are often used as representative systems to investigate the formation and stabilization of localized structural domains ("rafts"). In this work, we describe a self-consistent mean-field model that builds on molecular dynamics simulations to incorporate multiple lipid components and to investigate the lateral organization of such mixtures. The model predictions reveal regions of bimodal order on ternary plots that are in good agreement with experiment. Specifically, we have applied the model to ternary mixtures composed of dioleoylphosphatidylcholine:18:0 sphingomyelin:CHOL. This work provides insight into the specific intermolecular interactions that drive the formation of localized domains in these mixtures. The model makes use of molecular dynamics simulations to extract interaction parameters and to provide chain configuration order parameter libraries.
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Affiliation(s)
- Paul W Tumaneng
- Department of Biological, Chemical and Physical Sciences and Center for the Molecular Study of Condensed Soft Matter, Illinois Institute of Technology, Chicago, Illinois 60616, USA.
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262
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Pan J, Tristram-Nagle S, Nagle JF. Alamethicin aggregation in lipid membranes. J Membr Biol 2009; 231:11-27. [PMID: 19789905 DOI: 10.1007/s00232-009-9199-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 09/02/2009] [Indexed: 10/20/2022]
Abstract
X-ray scattering features induced by aggregates of alamethicin (Alm) were obtained in oriented stacks of model membranes of DOPC(diC18:1PC) and diC22:1PC. The first feature obtained near full hydration was Bragg rod in-plane scattering near 0.11 A(-1) in DOPC and near 0.08 A(-1) in diC22:1PC at a 1:10 Alm:lipid ratio. This feature is interpreted as bundles consisting of n Alm monomers in a barrel-stave configuration surrounding a water pore. Fitting the scattering data to previously published molecular dynamics simulations indicates that the number of peptides per bundle is n = 6 in DOPC and n >or= 9 in diC22:1PC. The larger bundle size in diC22:1PC is explained by hydrophobic mismatch of Alm with the thicker bilayer. A second diffuse scattering peak located at q(r) approximately 0.7 A(-1) is obtained for both DOPC and diC22:1PC at several peptide concentrations. Theoretical calculations indicate that this peak cannot be caused by the Alm bundle structure. Instead, we interpret it as being due to two-dimensional hexagonally packed clusters in equilibrium with Alm bundles. As the relative humidity was reduced, interactions between Alm in neighboring bilayers produced more peaks with three-dimensional crystallographic character that do not index with the conventional hexagonal space groups.
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Affiliation(s)
- Jianjun Pan
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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