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Li Y, Liu Y, Yang B, Li G, Chu H. Polarizable atomic multipole-based force field for cholesterol. J Biomol Struct Dyn 2024; 42:7747-7757. [PMID: 37565356 DOI: 10.1080/07391102.2023.2245045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 07/21/2023] [Indexed: 08/12/2023]
Abstract
Cholesterol is one of the essential component of lipid in membrane. We present a polarizable atomic multipole force field (FF) for the molecular dynamic simulation of cholesterol. The FF building process follows the computational framework as the atomic multipole optimized energetics for biomolecular applications (AMOEBA) model. In this framework, the electronics parameters, including atomic monopole moments, dipole moments, and quadrupole moments calculated from ab initio calculations in the gas phase, are applied to represent the charge distribution. Furthermore, the many-body polarization is modeled by following the same pattern of distributed atomic polarizabilities. Then, the bilayers composed of two typical phospholipid molecules, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), in a range of different cholesterol concentrations are built and implemented by molecular dynamics (MD) simulations based on the proposed polarizable FF. The simulation results are statistically analyzed to validate the feasibility of the proposed FF. The structural properties of the bilayers are calculated to compare with the related experimental values. The MD values show the same trend of experimental values changes.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Yan Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning, China
| | - Ye Liu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning, China
| | - Boya Yang
- Dalian Municipal Central Hospital, Liaoning, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning, China
| | - Huiying Chu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, Liaoning, China
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2
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Dufourc EJ. Wine tannins and their aggregation/release with lipids and proteins: Review and perspectives for neurodegenerative diseases. Biophys Chem 2024; 307:107178. [PMID: 38277878 DOI: 10.1016/j.bpc.2024.107178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/10/2024] [Accepted: 01/10/2024] [Indexed: 01/28/2024]
Abstract
Tannins are amphiphilic molecules, often polymeric, which can be generally described as a core containing hydrophobic aromatic rings surrounded by hydroxyl groups. They have been known for millennia and are part of human culture. They are ubiquitous in nature and are best known in the context of wine and tea tasting and food cultures. However, they are also very useful for human health, as they are powerful antioxidants capable of combating the constant aggressions of everyday life. However, their mode of action is only just beginning to be understood. This review, using physicochemical concepts, attempts to summarize current knowledge and present an integrated view of the complex relationship between tannins, proteins and lipids, in the context of wine drinking while eating. There are many thermodynamic equilibria governing the interactions between tannins, saliva proteins, lipid droplets in food, membranes and the taste receptors embedded in them. Taste sensations can be explained using these multiple equilibria: for example, astringency (dry mouth) can be explained by the strong binding of tannin micelles to the proline-rich proteins of saliva, suppressing their lubricating action on the palate. In the presence of lipid droplets in food, the equilibrium is shifted towards tannin-lipid complexes, a situation that reduces the astringency perceived when consuming a tannic wine with fatty foods, the so-called "camembert effect". Tannins bind preferentially to taste receptors located in mouth membranes, but can also fluidify lipids in the non-keratinized mucous membranes of the mouth, which can impair the functioning of taste receptors there. Cholesterol, present in large quantities in keratinized mucous membranes, stiffens them and thus prevents tannins from disrupting the conduction of information through other taste receptors. As tannins assemble and disassemble depending on whether they are in contact with proteins, lipids or taste receptors, a perspective on their potential use in the context of neurodegenerative diseases where fibrillation is a key phenomenon will also be discussed.
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Affiliation(s)
- Erick J Dufourc
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac, France; Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, Pessac, France.
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3
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Xu J, Karra V, Large DE, Auguste DT, Hung FR. Understanding the Mechanical Properties of Ultradeformable Liposomes Using Molecular Dynamics Simulations. J Phys Chem B 2023; 127:9496-9512. [PMID: 37879075 PMCID: PMC10641833 DOI: 10.1021/acs.jpcb.3c04386] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/19/2023] [Accepted: 10/04/2023] [Indexed: 10/27/2023]
Abstract
Improving drug delivery efficiency to solid tumor sites is a central challenge in anticancer therapeutic research. Our previous experimental study (Guo et al., Nat. Commun. 2018, 9, 130) showed that soft, elastic liposomes had increased uptake and accumulation in cancer cells and tumors in vitro and in vivo respectively, relative to rigid particles. As a first step toward understanding how liposomes' molecular structure and composition modulates their elasticity, we performed all-atom and coarse-grained classical molecular dynamics (MD) simulations of lipid bilayers formed by mixing a long-tailed unsaturated phospholipid with a short-tailed saturated lipid with the same headgroup. The former types of phospholipids considered were 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoleoyl-sn-glycero-3-phosphocholine (termed here DPMPC). The shorter saturated lipids examined were 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC), 1,2-didecanoyl-sn-glycero-3-phosphocholine (DDPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Several lipid concentrations and surface tensions were considered. Our results show that DOPC or DPMPC systems having 25-35 mol % of the shortest lipids DHPC or DDPC are the least rigid, having area compressibility moduli KA that are ∼10% smaller than the values observed in pure DOPC or DPMPC bilayers. These results agree with experimental measurements of the stretching modulus and lysis tension in liposomes with the same compositions. These mixed systems also have lower areas per lipid and form more uneven x-y interfaces with water, the tails of both primary and secondary lipids are more disordered, and the terminal methyl groups in the tails of the long lipid DOPC or DPMPC wriggle more in the vertical direction, compared to pure DOPC or DPMPC bilayers or their mixtures with the longer saturated lipid DLPC or DMPC. These observations confirm our hypothesis that adding increasing concentrations of the short unsaturated lipid DHPC or DDPC to DOPC or DPMPC bilayers alters lipid packing and thus makes the resulting liposomes more elastic and less rigid. No formation of lipid nanodomains was noted in our simulations, and no clear trends were observed in the lateral diffusivities of the lipids as the concentration, type of secondary lipid, and surface tension were varied.
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Affiliation(s)
- Jiaming Xu
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Vyshnavi Karra
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Danielle E. Large
- Department
of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Debra T. Auguste
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
- Department
of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Francisco R. Hung
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
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4
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Chipot C. Predictions from First-Principles of Membrane Permeability to Small Molecules: How Useful Are They in Practice? J Chem Inf Model 2023; 63:4533-4544. [PMID: 37449868 DOI: 10.1021/acs.jcim.3c00686] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Predicting from first-principles the rate of passive permeation of small molecules across the biological membrane represents a promising strategy for screening lead compounds upstream in the drug-discovery and development pipeline. One popular avenue for the estimation of permeation rates rests on computer simulations in conjunction with the inhomogeneous solubility-diffusion model, which requires the determination of the free-energy change and position-dependent diffusivity of the substrate along the translocation pathway through the lipid bilayer. In this Perspective, we will clarify the physical meaning of the membrane permeability inferred from such computer simulations, and how theoretical predictions actually relate to what is commonly measured experimentally. We will also examine why these calculations remain both technically challenging and overly computationally expensive, which has hitherto precluded their routine use in nonacademic settings. We finally synopsize possible research directions to meet these challenges, increase the predictive power of physics-based rates of passive permeation, and, by ricochet, improve their practical usefulness.
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Affiliation(s)
- Christophe Chipot
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, Unité Mixte de Recherche n◦7019, Université de Lorraine, 54500 Vandœuvre-lès-Nancy cedex, France
- Beckman Institute for Advanced Science and Technology, and Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, United States
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, United States
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5
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Rózsa ZB, Hantal G, Szőri M, Fábián B, Jedlovszky P. Understanding the Molecular Mechanism of Anesthesia: Effect of General Anesthetics and Structurally Similar Non-Anesthetics on the Properties of Lipid Membranes. J Phys Chem B 2023; 127:6078-6090. [PMID: 37368412 PMCID: PMC11404830 DOI: 10.1021/acs.jpcb.3c02976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
General anesthesia can be caused by various, chemically very different molecules, while several other molecules, many of which are structurally rather similar to them, do not exhibit anesthetic effects at all. To understand the origin of this difference and shed some light on the molecular mechanism of general anesthesia, we report here molecular dynamics simulations of the neat dipalmitoylphosphatidylcholine (DPPC) membrane as well as DPPC membranes containing the anesthetics diethyl ether and chloroform and the structurally similar non-anesthetics n-pentane and carbon tetrachloride, respectively. To also account for the pressure reversal of anesthesia, these simulations are performed both at 1 bar and at 600 bar. Our results indicate that all solutes considered prefer to stay both in the middle of the membrane and close to the boundary of the hydrocarbon domain, at the vicinity of the crowded region of the polar headgroups. However, this latter preference is considerably stronger for the (weakly polar) anesthetics than for the (apolar) non-anesthetics. Anesthetics staying in this outer preferred position increase the lateral separation between the lipid molecules, giving rise to a decrease of the lateral density. The lower lateral density leads to an increased mobility of the DPPC molecules, a decreased order of their tails, an increase of the free volume around this outer preferred position, and a decrease of the lateral pressure at the hydrocarbon side of the apolar/polar interface, a change that might well be in a causal relation with the occurrence of the anesthetic effect. All these changes are clearly reverted by the increase of pressure. Furthermore, non-anesthetics occur in this outer preferred position in a considerably smaller concentration and hence either induce such changes in a much weaker form or do not induce them at all.
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Affiliation(s)
- Zsófia B Rózsa
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria
| | - Milán Szőri
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - Balázs Fábián
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, CZ-16610 Prague 6, Czech Republic
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 6, H-3300 Eger, Hungary
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6
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Ruiz J, LoRicco JG, Soulère L, Castell MS, Grélard A, Kauffmann B, Dufourc EJ, Demé B, Popowycz F, Peters J. Membrane plasticity induced by myo-inositol derived archaeal lipids: chemical synthesis and biophysical characterization. Phys Chem Chem Phys 2023. [PMID: 37305972 DOI: 10.1039/d3cp01646c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Archaeal membrane lipids have specific structures that allow Archaea to withstand extreme conditions of temperature and pressure. In order to understand the molecular parameters that govern such resistance, the synthesis of 1,2-di-O-phytanyl-sn-glycero-3-phosphoinositol (DoPhPI), an archaeal lipid derived from myo-inositol, is reported. Benzyl protected myo-inositol was first prepared and then transformed to phosphodiester derivatives using a phosphoramidite based-coupling reaction with archaeol. Aqueous dispersions of DoPhPI alone or mixed with DoPhPC can be extruded and form small unilamellar vesicles, as detected by DLS. Neutron, SAXS, and solid-state NMR demonstrated that the water dispersions could form a lamellar phase at room temperature that then evolves into cubic and hexagonal phases with increasing temperature. Phytanyl chains were also found to impart remarkable and nearly constant dynamics to the bilayer over wide temperature ranges. All these new properties of archaeal lipids are proposed as providers of plasticity and thus means for the archaeal membrane to resist extreme conditions.
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Affiliation(s)
- Johal Ruiz
- Univ Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, UMR 5246, CNRS, ICBMS, Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires, Bât. E. Lederer, 1 Rue Victor Grignard, F-69622 Villeurbanne, France
| | | | - Laurent Soulère
- Univ Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, UMR 5246, CNRS, ICBMS, Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires, Bât. E. Lederer, 1 Rue Victor Grignard, F-69622 Villeurbanne, France
| | | | - Axelle Grélard
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
- Institut Européen de Chimie et Biologie, CNRS, Université de Bordeaux, INSERM, UAR3033, France
| | - Brice Kauffmann
- Institut Européen de Chimie et Biologie, CNRS, Université de Bordeaux, INSERM, UAR3033, France
| | - Erick J Dufourc
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France
- Institut Européen de Chimie et Biologie, CNRS, Université de Bordeaux, INSERM, UAR3033, France
| | - Bruno Demé
- Institut Laue-Langevin, 38000 Grenoble, France.
| | - Florence Popowycz
- Univ Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, UMR 5246, CNRS, ICBMS, Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires, Bât. E. Lederer, 1 Rue Victor Grignard, F-69622 Villeurbanne, France
| | - Judith Peters
- Institut Laue-Langevin, 38000 Grenoble, France.
- Univ. Grenoble Alpes, LiPhy, CNRS, 38000 Grenoble, France
- Institut Universitaire de France, France
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7
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Alsop DC, Ercan E, Girard OM, Mackay AL, Michal CA, Varma G, Vinogradov E, Duhamel G. Inhomogeneous magnetization transfer imaging: Concepts and directions for further development. NMR IN BIOMEDICINE 2023; 36:e4808. [PMID: 35916067 DOI: 10.1002/nbm.4808] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 07/27/2022] [Accepted: 07/28/2022] [Indexed: 05/23/2023]
Abstract
Off-resonance radio frequency irradiation can induce the ordering of proton spins in the dipolar fields of their neighbors, in molecules with restricted mobility. This dipolar order decays with a characteristic relaxation time, T1D , that is very different from the T1 and T2 relaxation of the nuclear alignment with the main magnetic field. Inhomogeneous magnetization transfer (ihMT) imaging is a refinement of magnetization transfer (MT) imaging that isolates the MT signal dependence on dipolar order relaxation times within motion-constrained molecules. Because T1D relaxation is a unique contrast mechanism, ihMT may enable improved characterization of tissue. Initial work has stressed the high correlation between ihMT signal and myelin density. Dipolar order relaxation appears to be much longer in membrane lipids than other molecules. Recent work has shown, however, that ihMT acquisitions may also be adjusted to emphasize different ranges of T1D . These newer approaches may be sensitive to other microstructural components of tissue. Here, we review the concepts and history of ihMT and outline the requirements for further development to realize its full potential.
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Affiliation(s)
- David C Alsop
- Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Ece Ercan
- MR Clinical Science, Philips, Best, The Netherlands
| | | | - Alex L Mackay
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Carl A Michal
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gopal Varma
- Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Elena Vinogradov
- Department of Radiology and Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
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8
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Rathod AK, Chavda D, Manna M. Phase Transition and Phase Separation in Realistic Thylakoid Lipid Membrane of Marine Algae in All-Atom Simulations. J Chem Inf Model 2023. [PMID: 37075469 DOI: 10.1021/acs.jcim.2c01614] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
Thylakoid membranes are specialized membranes predominantly composed of uncommon galacto- and sulfolipids, having distinct roles in photosynthesis. Large acyl chain variety and richness in polyunsaturated fatty acid (PUFA) content of thylakoid lipids further add to the compositional complexity. The function of these membrane systems is intimately dependent on the fluidity of its lipid matrix, which is strongly modulated by the lipid composition and temperature. The present work, employing extensive atomistic simulations, provides the first atomistic view of the phase transition and domain coexistence in a model membrane composed of thylakoid lipids of a commercially important red alga Gracilaria corticata between 10 and 40 °C. The growth and photosynthetic activity of marine algae are greatly influenced by the seawater temperature. So far, little is known about the molecular organization of lipids in thylakoid membranes, in particular their adaptive arrangements under temperature stress. Our simulations show that the algal thylakoid membrane undergoes a transition from a gel-like phase at a low temperature, 10-15 °C, to a homogeneous liquid-crystalline phase at a high temperature, 40 °C. Clear evidence of spontaneous phase separation into coexisting nanoscale domains is detected at intermediate temperatures nearing the optimal growth temperature range. Particularly, at 25-30 °C, we identified the formation of a stable ripple phase, where the gel-like domains rich in saturated and nearly hexagonally packed lipids were separated from fluid-like domains enriched in lipids containing PUFA chains. The phase separation is driven by the spontaneous and preferential segregation of lipids into differentially ordered domains, mainly depending on the acyl chain types. Cholesterol impairs the phase transition and the emergence of domains and induces a fairly uniform liquid-ordered phase in the membrane over the temperatures studied. This work improves the understanding of the properties and reorganization of lipids in the thylakoid membrane in response to temperature variation.
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Affiliation(s)
- Arun K Rathod
- Applied Phycology and Biotechnology Division, CSIR Central Salt & Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Dhruvil Chavda
- Applied Phycology and Biotechnology Division, CSIR Central Salt & Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Moutusi Manna
- Applied Phycology and Biotechnology Division, CSIR Central Salt & Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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9
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Doktorova M, Khelashvili G, Ashkar R, Brown MF. Molecular simulations and NMR reveal how lipid fluctuations affect membrane mechanics. Biophys J 2023; 122:984-1002. [PMID: 36474442 PMCID: PMC10111610 DOI: 10.1016/j.bpj.2022.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 11/21/2022] [Accepted: 12/02/2022] [Indexed: 12/07/2022] Open
Abstract
Lipid bilayers form the main matrix of functional cell membranes, and their dynamics underlie a host of physical and biological processes. Here we show that elastic membrane properties and collective molecular dynamics (MD) are related by the mean-square amplitudes (order parameters) and relaxation rates (correlation times) of lipid acyl chain motions. We performed all-atom MD simulations of liquid-crystalline bilayers that allow direct comparison with carbon-hydrogen (CH) bond relaxations measured with NMR spectroscopy. Previous computational and theoretical approaches have assumed isotropic relaxation, which yields inaccurate description of lipid chain dynamics and incorrect data interpretation. Instead, the new framework includes a fixed bilayer normal (director axis) and restricted anisotropic motion of the CH bonds in accord with their segmental order parameters, enabling robust validation of lipid force fields. Simulated spectral densities of thermally excited CH bond fluctuations exhibited well-defined spin-lattice (Zeeman) relaxations analogous to those in NMR measurements. Their frequency signature could be fit to a simple power-law function, indicative of nematic-like collective dynamics. Moreover, calculated relaxation rates scaled as the squared order parameters yielding an apparent κC modulus for bilayer bending. Our results show a strong correlation with κC values obtained from solid-state NMR studies of bilayers without and with cholesterol as validated by neutron spin-echo measurements of membrane elasticity. The simulations uncover a critical role of interleaflet coupling in membrane mechanics and thus provide important insights into molecular sites of emerging elastic properties within lipid bilayers.
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Affiliation(s)
- Milka Doktorova
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia.
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York; Institute of Computational Biomedicine, Weill Cornell Medical College of Cornell University, New York, New York
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, Virginia; Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, Virginia
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona; Program in Applied Mathematics, University of Arizona, Tucson, Arizona.
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10
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Morvan E, Taib-Maamar N, Grélard A, Loquet A, Dufourc EJ. Dynamic Sorting of Mobile and Rigid Molecules in Biomembranes by Magic-Angle Spinning 13C NMR. Anal Chem 2023; 95:3596-3605. [PMID: 36749686 DOI: 10.1021/acs.analchem.2c04185] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Understanding the membrane dynamics of complex systems is essential to follow their function. As molecules in membranes can be in a rigid or mobile state depending on external (temperature, pressure) or internal (pH, domains, etc.) conditions, we propose an in-depth examination of NMR methods to filter highly mobile molecular parts from others that are in more restricted environments. We have thus developed a quantitative magic-angle spinning (MAS) 13C NMR approach coupled with cross-polarization (CP) and/or Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) on rigid and fluid unlabeled model membranes. We demonstrate that INEPT can detect only very mobile lipid headgroups in gel (solid-ordered) phases; the remaining rigid parts are only detected with CP. A direct correlation is established between the normalized line intensity as obtained by CP and the C-H (C-D) order parameters measured by wide-line 2H NMR or extracted from molecular dynamics: ICP/IDPeq ≈ 5|SCH|, indicating that when the order is greater than 0.2-0.3 (maximum value of 0.5 for chain CH2), only rigid parts can be filtered and detected using CP techniques. In very fluid (liquid-disordered) membranes, where there are many more active motions, both INEPT and CP detect resonances, with, however, a clear propensity of each technique to detect mobile and restricted molecular parts, respectively. Interestingly, the 13C NMR chemical shift of lipid hydrocarbon chains can be used to monitor order-disorder phase transitions and calculate the fraction of chain defects (rotamers) and the part of the transition enthalpy due to bond rotations (6-7 kJ·mol-1 for dimyristolphosphatidylcholine, DMPC). Cholesterol-containing membranes (liquid-ordered phases) can be dynamically contrasted as the rigid-body sterol is mainly detected by the CP technique, with a contact time of 1 ms, and the phospholipid by INEPT. Our work opens up a straightforward, robust, and cost-effective route for the determination of membrane dynamics by taking advantage of well-resolved conventional 13C NMR experiments without the need of isotopic labeling.
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Affiliation(s)
- Estelle Morvan
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac 33600, France
| | - Nada Taib-Maamar
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, Pessac 33600, France
| | - Axelle Grélard
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac 33600, France.,Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, Pessac 33600, France
| | - Antoine Loquet
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac 33600, France.,Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, Pessac 33600, France
| | - Erick J Dufourc
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac 33600, France.,Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, Pessac 33600, France
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11
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Morvan E, Taib-Maamar N, Grélard A, Loquet A, Dufourc EJ. Bio-membranes: Picosecond to second dynamics and plasticity as deciphered by solid state NMR. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184097. [PMID: 36442647 DOI: 10.1016/j.bbamem.2022.184097] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022]
Abstract
Since the first membrane models in the 1970s, the concept of biological membranes has evolved considerably. The membrane is now seen as a very complex mixture whose dynamic behavior is even more complex. Solid-state NMR is well suited for such studies as it can probe the movements of the membrane from picoseconds to seconds. Two NMR observables can be used: motionally averaged spectra and relaxation times. They bring information on order parameters, phase transitions, correlation times, activation energies and membrane elasticity. Spectra are used to determine the nature of the membrane phase. The order parameters can be measured directly from spectra that are dominated by quadrupolar, dipolar and chemical shielding magnetic interactions and allow describing the lipid membrane as being very rigid at the glycerol and chain level and very fluid at its center and surface. Correlation times and activation energies can be measured for intramolecular motions (pico to nanoseconds), molecular motions (nano to 100 ns) and collective modes of membrane deformation (microseconds). Sterols modulate membrane phases, order parameters, correlation times and membrane elasticity. In general terms, sterols tend to act to reduce the impact of environmental changes on molecular order and dynamics. They can be described as regulators of membrane dynamics by keeping them in a state of dynamics that changes very little when the temperature or other factors change. The presence of such large-scale membrane dynamics is proposed as a means of adapting to evolutionary constraints.
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Affiliation(s)
- Estelle Morvan
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac, France
| | - Nada Taib-Maamar
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, 33600 Pessac, France
| | - Axelle Grélard
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac, France; Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, 33600 Pessac, France
| | - Antoine Loquet
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac, France; Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, 33600 Pessac, France
| | - Erick J Dufourc
- Institut Européen de Chimie et Biologie UAR3033 CNRS, University of Bordeaux, INSERM US01, Pessac, France; Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, 33600 Pessac, France.
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12
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Baccouch R, Shi Y, Vernay E, Mathelié-Guinlet M, Taib-Maamar N, Villette S, Feuillie C, Rascol E, Nuss P, Lecomte S, Molinari M, Staneva G, Alves ID. The impact of lipid polyunsaturation on the physical and mechanical properties of lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184084. [PMID: 36368636 DOI: 10.1016/j.bbamem.2022.184084] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 10/21/2022] [Accepted: 10/25/2022] [Indexed: 11/09/2022]
Abstract
The lipid composition of cellular membranes and the balance between the different lipid components can be impacted by aging, certain pathologies, specific diets and other factors. This is the case in a subgroup of individuals with psychiatric disorders, such as schizophrenia, where cell membranes of patients have been shown to be deprived in polyunsaturated fatty acids (PUFAs), not only in brain areas where the target receptors are expressed but also in peripheral tissues. This PUFA deprivation thus represents a biomarker of such disorders that might impact not only the interaction of antipsychotic medications with these membranes but also the activation and signaling of the targeted receptors embedded in the lipid membrane. Therefore, it is crucial to understand how PUFAs levels alterations modulate the different physical properties of membranes. In this paper, several biophysical approaches were combined (Laurdan fluorescence spectroscopy, atomic force microscopy, differential scanning calorimetry, molecular modeling) to characterize membrane properties such as fluidity, elasticity and thickness in PUFA-enriched cell membranes and lipid model systems reflecting the PUFA imbalance observed in some diseases. The impact of both the number of unsaturations and their position along the chain on the above properties was investigated. Briefly, data revealed that PUFA presence in membranes increases membrane fluidity, elasticity and flexibility and decreases its thickness and order parameter. Both the level of unsaturation and their position affect these membrane properties.
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Affiliation(s)
- Rim Baccouch
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Yarong Shi
- Laboratoire de Recherche en Nanosciences, LRN EA4682, University of Reims Champagne Ardenne, France
| | - Emilie Vernay
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Marion Mathelié-Guinlet
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Nada Taib-Maamar
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Sandrine Villette
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Cécile Feuillie
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Estelle Rascol
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Philippe Nuss
- Centre de Recherche Saint-Antoine, INSERM UMRS 938, Sorbonne Université, Paris, France; Service de psychiatrie et de psychologie médicale, Sorbonne Université, Hôpital Saint-Antoine, AP-HP, Paris, France
| | - Sophie Lecomte
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Michael Molinari
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France
| | - Galya Staneva
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.21, 1113 Sofia, Bulgaria
| | - Isabel D Alves
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Bat B14, allée Geoffroy St. Hilaire, F-33600 Pessac, France.
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13
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Heller WT. Small-Angle Neutron Scattering for Studying Lipid Bilayer Membranes. Biomolecules 2022; 12:1591. [PMID: 36358941 PMCID: PMC9687511 DOI: 10.3390/biom12111591] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/18/2022] [Accepted: 10/26/2022] [Indexed: 09/23/2023] Open
Abstract
Small-angle neutron scattering (SANS) is a powerful tool for studying biological membranes and model lipid bilayer membranes. The length scales probed by SANS, being from 1 nm to over 100 nm, are well-matched to the relevant length scales of the bilayer, particularly when it is in the form of a vesicle. However, it is the ability of SANS to differentiate between isotopes of hydrogen as well as the availability of deuterium labeled lipids that truly enable SANS to reveal details of membranes that are not accessible with the use of other techniques, such as small-angle X-ray scattering. In this work, an overview of the use of SANS for studying unilamellar lipid bilayer vesicles is presented. The technique is briefly presented, and the power of selective deuteration and contrast variation methods is discussed. Approaches to modeling SANS data from unilamellar lipid bilayer vesicles are presented. Finally, recent examples are discussed. While the emphasis is on studies of unilamellar vesicles, examples of the use of SANS to study intact cells are also presented.
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Affiliation(s)
- William T Heller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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14
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Shamaprasad P, Frame CO, Moore TC, Yang A, Iacovella CR, Bouwstra JA, Bunge AL, McCabe C. Using molecular simulation to understand the skin barrier. Prog Lipid Res 2022; 88:101184. [PMID: 35988796 PMCID: PMC10116345 DOI: 10.1016/j.plipres.2022.101184] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 11/15/2022]
Abstract
Skin's effectiveness as a barrier to permeation of water and other chemicals rests almost entirely in the outermost layer of the epidermis, the stratum corneum (SC), which consists of layers of corneocytes surrounded by highly organized lipid lamellae. As the only continuous path through the SC, transdermal permeation necessarily involves diffusion through these lipid layers. The role of the SC as a protective barrier is supported by its exceptional lipid composition consisting of ceramides (CERs), cholesterol (CHOL), and free fatty acids (FFAs) and the complete absence of phospholipids, which are present in most biological membranes. Molecular simulation, which provides molecular level detail of lipid configurations that can be connected with barrier function, has become a popular tool for studying SC lipid systems. We review this ever-increasing body of literature with the goals of (1) enabling the experimental skin community to understand, interpret and use the information generated from the simulations, (2) providing simulation experts with a solid background in the chemistry of SC lipids including the composition, structure and organization, and barrier function, and (3) presenting a state of the art picture of the field of SC lipid simulations, highlighting the difficulties and best practices for studying these systems, to encourage the generation of robust reproducible studies in the future. This review describes molecular simulation methodology and then critically examines results derived from simulations using atomistic and then coarse-grained models.
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Affiliation(s)
- Parashara Shamaprasad
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Chloe O Frame
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Timothy C Moore
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Alexander Yang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Christopher R Iacovella
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Joke A Bouwstra
- Division of BioTherapeutics, LACDR, Leiden University, 2333 CC Leiden, the Netherlands
| | - Annette L Bunge
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, United States of America
| | - Clare McCabe
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America; School of Engineering and Physical Science, Heriot-Watt University, Edinburgh, United Kingdom.
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15
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Joodaki F, Martin LM, Greenfield ML. Generation and Computational Characterization of a Complex Staphylococcus aureus Lipid Bilayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9481-9499. [PMID: 35901279 DOI: 10.1021/acs.langmuir.2c00483] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Studies indicate a crucial cell membrane role in the antibiotic resistance of Staphylococcus aureus. To simulate its membrane structure and dynamics, a complex molecular-scale computational representation of the S. aureus lipid bilayer was developed. Phospholipid types and their amounts were optimized by reverse Monte Carlo to represent characterization data from the literature, leading to 19 different phospholipid types that combine three headgroups [phosphatidylglycerol, lysyl-phosphatidylglycerol (LPG), and cardiolipin] and 10 tails, including iso- and anteiso-branched saturated chains. The averaged lipid bilayer thickness was 36.7 Å, and area per headgroup was 67.8 Å2. Phosphorus and nitrogen density profiles showed that LPG headgroups tended to be bent and oriented more parallel to the bilayer plane. The water density profile showed that small amounts reached the membrane center. Carbon density profiles indicated hydrophobic interactions for all lipids in the middle of the bilayer. Bond vector order parameters along each tail demonstrated different C-H ordering even within distinct lipids of the same type; however, all tails followed similar trends in average order parameter. These complex simulations further revealed bilayer insights beyond those attainable with monodisperse, unbranched lipids. Longer tails often extended into the opposite leaflet. Carbon at and beyond a branch showed significantly decreased ordering compared to carbon in unbranched tails; this feature arose in every branched lipid. Diverse tail lengths distributed these disordered methyl groups throughout the middle third of the bilayer. Distributions in mobility and ordering reveal diverse properties that cannot be obtained with monodisperse lipids.
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Affiliation(s)
- Faramarz Joodaki
- Department of Chemical Engineering, University of Rhode Island, 360 Fascitelli Center for Advanced Engineering, Kingston, Rhode Island 02881, United States
| | - Lenore M Martin
- Department of Cell and Molecular Biology, University of Rhode Island, 120 Flagg Road, Kingston, Rhode Island 02881, United States
| | - Michael L Greenfield
- Department of Chemical Engineering, University of Rhode Island, 360 Fascitelli Center for Advanced Engineering, Kingston, Rhode Island 02881, United States
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16
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Yuan S, Zhang H, Yuan S. Theoretical insights into the uptake of sulfonamides onto phospholipid bilayers: Mechanisms, interaction and toxicity evaluation. JOURNAL OF HAZARDOUS MATERIALS 2022; 435:129033. [PMID: 35525012 DOI: 10.1016/j.jhazmat.2022.129033] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/13/2022] [Accepted: 04/26/2022] [Indexed: 06/14/2023]
Abstract
Sulfonamides (SAs) are now recognized as the main emerging environmental pollutants in aquatic environments. Although the bioaccumulation capacities of SAs have been confirmed, the pathway for the penetration of the SAs into lipid bilayer has been not fully understood. In this study, the bioaccumulation mechanism of four typical SAs onto the dipalmitoyl phosphatidylcholine (DPPC) lipid bilayer and their effects on the properties of DPPC bilayer were employed and evaluated respectively by using molecular dynamics simulations. Results show that from the viewpoint of thermodynamics, it is favorable for these SAs partitioning to DPPC bilayer. The accommodation of four SAs onto the lipid membrane needs to undergo several processes, which include the contact stage, transformation stage, and absorption stage. Besides, the sulfamethoxazole (SMX) and sulfamethazine (SMZ) show a strong preference for the DPPC phase rather than the interface region while the sulfadiazine (SDZ) and sulfametoxydiazine (SMD) have similar tendencies in the interface region and DPPC phase. Furthermore, the cytotoxicity of SAs is reflected in their ability to affect the electrostatic potential of the membrane and to reduce the thickness of phospholipid bilayers. This molecular-level study provided an insightful understanding of the toxicity and bioaccumulation of SAs.
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Affiliation(s)
- Shideng Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Heng Zhang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Shiling Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China.
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17
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Hu P, Shao J, Qian G, Adeleye AS, Hao T. Removal of tetracycline by aerobic granular sludge from marine aquaculture wastewater: A molecular dynamics investigation. BIORESOURCE TECHNOLOGY 2022; 355:127286. [PMID: 35545206 DOI: 10.1016/j.biortech.2022.127286] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/03/2022] [Accepted: 05/05/2022] [Indexed: 06/15/2023]
Abstract
Although biological treatment of marine aquaculture wastewater is promising, the fundamental principles driving the adsorption of tetracycline to microbial cell membrane are not well understood. Using a combination of experiments and molecular dynamics (MD) simulations, the mechanism underlying the biological removal of tetracycline from seawater was investigated. More than 90% tetracycline removal was achieved in an aerobic granular sludge system, with degradation accounting for 30% of total removal. A model of the tetracycline-dipalmitoylphosphatidylcholine lipid bilayers was established to elucidate the transport mechanism of tetracycline from bulk solution to microorganisms' cell membrane. 62% of the driving force for tetracycline adsorption on the cell membrane originated from electrostatic attraction. The electrophilic groups on tetracycline (amino and aromatic groups) were attracted to the phosphate groups in the cell membrane. Sodium ions, which are abundant in seawater, decreased the interaction energy between tetracycline and the cell membrane.
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Affiliation(s)
- Peng Hu
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | - Jingyi Shao
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | - Guangsheng Qian
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | - Adeyemi S Adeleye
- Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697-2175, USA
| | - Tianwei Hao
- Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China.
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18
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Saunders M, Wineman-Fisher V, Jakobsson E, Varma S, Pandit SA. High-Dimensional Parameter Search Method to Determine Force Field Mixing Terms in Molecular Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2840-2851. [PMID: 35192365 PMCID: PMC9801415 DOI: 10.1021/acs.langmuir.1c03105] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Molecular dynamics (MD) force fields for lipids and ions are typically developed independently of one another. In simulations consisting of both lipids and ions, lipid-ion interaction energies are estimated using a predefined set of mixing rules for Lennard-Jones (LJ) interactions. This, however, does not guarantee their reliability. In fact, compared to the quantum mechanical reference data, Lorentz-Berthelot mixing rules substantially underestimate the binding energies of Na+ ions with small-molecule analogues of lipid headgroups, yielding errors on the order of 80 and 130 kJ/mol, respectively, for methyl acetate and diethyl phosphate. Previously, errors associated with mixing force fields have been reduced using approaches such as "NB-fix" in which LJ interactions are computed using explicit cross terms rather than those from mixing rules. Building on this idea, we derive explicit lipid-ion cross terms that also may implicitly include many-body cooperativity effects. Additionally, to account for the interdependency between cross terms, we optimize all cross terms simultaneously by performing high-dimensional searches using our ParOpt software. The cross terms we obtain reduce the errors due to mixing rules to below 10 kJ/mol. MD simulation of the lipid bilayer conducted using these optimized cross terms resolves the structural discrepancies between our previous simulations and small-angle X-ray and neutron scattering experiments. These results demonstrate that simulations of lipid bilayers with ions that are accurate up to structural data from scattering experiments can be performed without explicit polarization terms. However, it is worth noting that such NB-fix cross terms are not based on any physical principle; a polarizable lipid model would be more realistic and is still desired. Our approach is generic and can be applied to improve the accuracies of simulations employing mixed force fields.
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Affiliation(s)
| | | | - Eric Jakobsson
- Department of Molecular and Integrative Physiology, Beckman Institute for Advanced Science and Technology, and Department of Biochemistry, Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, United States
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19
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Oliveira AA, Róg T, da Silva ABF, Amaro RE, Johnson MS, Postila PA. Examining the Effect of Charged Lipids on Mitochondrial Outer Membrane Dynamics Using Atomistic Simulations. Biomolecules 2022; 12:183. [PMID: 35204684 PMCID: PMC8961577 DOI: 10.3390/biom12020183] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/11/2022] Open
Abstract
The outer mitochondrial membrane (OMM) is involved in multiple cellular functions such as apoptosis, inflammation and signaling via its membrane-associated and -embedded proteins. Despite the central role of the OMM in these vital phenomena, the structure and dynamics of the membrane have regularly been investigated in silico using simple two-component models. Accordingly, the aim was to generate the realistic multi-component model of the OMM and inspect its properties using atomistic molecular dynamics (MD) simulations. All major lipid components, phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS), were included in the probed OMM models. Because increased levels of anionic PS lipids have potential effects on schizophrenia and, more specifically, on monoamine oxidase B enzyme activity, the effect of varying the PS concentration was explored. The MD simulations indicate that the complex membrane lipid composition (MLC) behavior is notably different from the two-component PC-PE model. The MLC changes caused relatively minor effects on the membrane structural properties such as membrane thickness or area per lipid; however, notable effects could be seen with the dynamical parameters at the water-membrane interface. Increase of PS levels appears to slow down lateral diffusion of all lipids and, in general, the presence of anionic lipids reduced hydration and slowed down the PE headgroup rotation. In addition, sodium ions could neutralize the membrane surface, when PI was the main anionic component; however, a similar effect was not seen for high PS levels. Based on these results, it is advisable for future studies on the OMM and its protein or ligand partners, especially when wanting to replicate the correct properties on the water-membrane interface, to use models that are sufficiently complex, containing anionic lipid types, PI in particular.
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Affiliation(s)
- Aline A. Oliveira
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, CA 92093-0340, USA; (A.A.O.); (R.E.A.)
- Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, São Carlos 13560-970, Brazil;
| | - Tomasz Róg
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland;
| | - Albérico B. F. da Silva
- Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, São Carlos 13560-970, Brazil;
| | - Rommie E. Amaro
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, CA 92093-0340, USA; (A.A.O.); (R.E.A.)
| | - Mark S. Johnson
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland;
- InFLAMES Research Flagship Center, Åbo Akademi University, 20520 Turku, Finland
| | - Pekka A. Postila
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, CA 92093-0340, USA; (A.A.O.); (R.E.A.)
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland;
- InFLAMES Research Flagship Center, Åbo Akademi University, 20520 Turku, Finland
- Institute of Biomedicine, Kiinamyllynkatu 10, Integrative Physiology and Pharmacy, University of Turku, FI-20520 Turku, Finland
- Aurlide Ltd., FI-21420 Lieto, Finland
- InFLAMES Research Flagship Center, University of Turku, FI-20520 Turku, Finland
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20
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Yuan S, Zhang H, Wang X, Zhang H, Zhang Z, Yuan S. Molecular insights into the uptake of SiO 2 nanoparticles on phospholipid membrane: Effect of surface properties and particle size. Colloids Surf B Biointerfaces 2021; 210:112250. [PMID: 34861541 DOI: 10.1016/j.colsurfb.2021.112250] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 11/24/2022]
Abstract
Silica (SiO2) nanoparticles (NPs) have attracted much attention due to the potential for a wide range of applications and they have been confirmed to be hazardous to humans. Partitioning to phospholipid bilayers is an important way for their bioaccumulation. However, the detailed mechanism of SiO2 NPs uptake by membrane phospholipids remains uncertain. In this work, molecular dynamics (MD) simulations were employed to study the uptake process of SiO2 NPs into DPPC bilayers. Results show that these SiO2 NPs uptake onto DPPC bilayer surface is favorable from the viewpoint of thermodynamics. During the uptake process, the SiO2 NP needed to adjust the angle of interaction with the DPPC surface until the most stable adsorption configuration was reached. After incorporating into DPPC bilayers, the interaction between PO4- group and SiO2 particle is stronger than -N+(CH3)3 group and SiO2. Small SiO2 NP was found to adsorb to the surface of DPPC bilayer without disturbing the morphology or membrane. In contract, bioaccumulation of large SiO2 NP to DPPC induced a strong local membrane deformation. In addition, the effect of SiO2 NP surface functionalization on its interaction with DPPC was also investigated. This molecular-level study reports a complete description of the interaction between SiO2 NPs and DPPC bilayer, aiming to provide some insights for the further work on the bioaccumulation and hemolytic activity of SiO2 NPs.
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Affiliation(s)
- Shideng Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Heng Zhang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Xueyu Wang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Hengming Zhang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Zhenyu Zhang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Shiling Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China.
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21
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Molecular-dynamics-simulation-guided membrane engineering allows the increase of membrane fatty acid chain length in Saccharomyces cerevisiae. Sci Rep 2021; 11:17333. [PMID: 34462478 PMCID: PMC8405694 DOI: 10.1038/s41598-021-96757-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 08/05/2021] [Indexed: 11/08/2022] Open
Abstract
The use of lignocellulosic-based fermentation media will be a necessary part of the transition to a circular bio-economy. These media contain many inhibitors to microbial growth, including acetic acid. Under industrially relevant conditions, acetic acid enters the cell predominantly through passive diffusion across the plasma membrane. The lipid composition of the membrane determines the rate of uptake of acetic acid, and thicker, more rigid membranes impede passive diffusion. We hypothesized that the elongation of glycerophospholipid fatty acids would lead to thicker and more rigid membranes, reducing the influx of acetic acid. Molecular dynamics simulations were used to predict the changes in membrane properties. Heterologous expression of Arabidopsis thaliana genes fatty acid elongase 1 (FAE1) and glycerol-3-phosphate acyltransferase 5 (GPAT5) increased the average fatty acid chain length. However, this did not lead to a reduction in the net uptake rate of acetic acid. Despite successful strain engineering, the net uptake rate of acetic acid did not decrease. We suggest that changes in the relative abundance of certain membrane lipid headgroups could mitigate the effect of longer fatty acid chains, resulting in a higher net uptake rate of acetic acid.
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22
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Dufourc EJ. Wine tannins, saliva proteins and membrane lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183670. [PMID: 34111413 DOI: 10.1016/j.bbamem.2021.183670] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 06/03/2021] [Indexed: 12/12/2022]
Abstract
Polyphenols have been part of human culture for about 6000 years. However, their mode of action in relation to wine tasting while eating is only beginning to be understood. This review, using analytical techniques and physicochemical concepts, attempts to summarize current knowledge and present an integrated view of the complex relationship between tannins, salivary proteins, lipids in food and in oral membranes. The action of tannins on taste sensations and astringency depends on their colloidal state. Although taste sensations are most likely due to interactions with taste receptors, astringency results from strong binding to proline-rich salivary proteins that otherwise lubricate the palate. Tannins disorder non-keratinized mucosa in mouth, possibly perturbing taste receptor function. The 10-15% ethanol present in wines potentiates this action. Cholesterol present in large quantities in keratinized mucosa prevents any disordering action on these oral membranes. Polyphenols bind strongly to the lipid droplets of fatty foods, a situation that reduces the astringency perceived when drinking a tannic wine, the so-called "camembert effect". Based on binding constants mainly measured by NMR, a comprehensive thermodynamic model of the interrelation between polyphenols, salivary proteins, lipids and taste receptors is presented.
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Affiliation(s)
- Erick J Dufourc
- Institute of Chemistry and Biology of Membranes and Nanoobjects, UMR5248, CNRS, University of Bordeaux, Bordeaux Polytechnic Institute, Allée Geoffroy Saint Hilaire, 33600 Pessac, France.
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23
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Mahmoudzadeh M, Magarkar A, Koivuniemi A, Róg T, Bunker A. Mechanistic Insight into How PEGylation Reduces the Efficacy of pH-Sensitive Liposomes from Molecular Dynamics Simulations. Mol Pharm 2021; 18:2612-2621. [PMID: 34096310 PMCID: PMC8289284 DOI: 10.1021/acs.molpharmaceut.1c00122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Liposome-based drug
delivery systems composed of DOPE stabilized
with cholesteryl hemisuccinate (CHMS) have been proposed as a drug
delivery mechanism with pH-triggered release as the anionic form (CHSa)
is protonated (CHS) at reduced pH; PEGylation is known to decrease
this pH sensitivity. In this manuscript, we set out to use molecular
dynamics (MD) simulations with a model with all-atom resolution to
provide insight into why incorporation of poly(ethyleneglycol) (PEG)
into DOPE–CHMS liposomes reduces their pH sensitivity; we also
address two additional questions: (1) How CHSa stabilizes DOPE bilayers
into a lamellar conformation at a physiological pH of 7.4? and (2)
how the change from CHSa to CHS at acidic pH triggers the destabilization
of DOPE bilayers? We found that (A) CHSa stabilizes the DOPE lipid
membrane by increasing the hydrophilicity of the bilayer surface,
(B) when CHSa changes to CHS by pH reduction, DOPE bilayers are destabilized
due to a reduction in bilayer hydrophilicity and a reduction in the
area per lipid, and (C) PEG stabilizes DOPE bilayers into the lamellar
phase, thus reducing the pH sensitivity of the liposomes by increasing
the area per lipid through penetration into the bilayer, which is
our main focus.
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Affiliation(s)
- Mohammad Mahmoudzadeh
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00100 Helsinki, Finland
| | - Aniket Magarkar
- Medicinal Chemistry, Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, D-88397 Biberach a.d. Riss, Germany
| | - Artturi Koivuniemi
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00100 Helsinki, Finland
| | - Tomasz Róg
- Faculty of Pharmacy, University of Helsinki, P.O. Box 56, Viikinkaarie 5 E, FI-00014 Helsinki, Finland
| | - Alex Bunker
- Faculty of Pharmacy, University of Helsinki, P.O. Box 56, Viikinkaarie 5 E, FI-00014 Helsinki, Finland
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24
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Kiriakidi S, Chatzigiannis C, Papaemmanouil C, Tzakos AG, Cournia Z, Mavromoustakos T. Interplay of cholesterol, membrane bilayers and the AT1R: A cholesterol consensus motif on AT1R is revealed. Comput Struct Biotechnol J 2020; 19:110-120. [PMID: 33384858 PMCID: PMC7758360 DOI: 10.1016/j.csbj.2020.11.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/21/2020] [Accepted: 11/23/2020] [Indexed: 11/18/2022] Open
Abstract
Hypertension, mediated by the Angiotensin II receptor type 1 (AT1R), is still the major cause of premature death despite the discovery of novel therapeutics, highlighting the importance of an in depth understanding of the drug-AT1R recognition mechanisms coupled with the impact of the membrane environment on the interaction of drugs with AT1R. Herein, we examine the interplay of cholesterol-lipid-candesartan and the AT1R using Molecular Dynamics simulations of a model membrane consisting of 60:40 mol%. DPPC:cholesterol, candesartan and the AT1R, mimicking the physiological cholesterol concentration in sarcolemma membranes. The simulations of the model membrane of 60:40 mol%. DPPC:cholesterol were further validated using DOSY NMR experiments. Interestingly, our results suggest a significant role of cholesterol in the AT1R function imposed through a Cholesterol Consensus Motif (CCM) in the receptor, which could be crucial in the drug binding process. Candesartan diffusion towards AT1R through incorporation into lipid bilayers, appears to be retarded by the presence of cholesterol. However, its direct approach towards AT1R may be facilitated through the mobility induced on the N-terminus by the cholesterol binding on the CCM these novel insights could pave the way towards the development of more potent pharmaceutical agents to combat hypertension more effectively.
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Affiliation(s)
- Sofia Kiriakidi
- National and Kapodistrian University of Athens, Department of Chemistry, Athens, Greece
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
| | - Christos Chatzigiannis
- University of Ioannina, Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece
| | - Christina Papaemmanouil
- University of Ioannina, Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece
| | - Andreas G. Tzakos
- University of Ioannina, Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
- Corresponding authors.
| | - Thomas Mavromoustakos
- National and Kapodistrian University of Athens, Department of Chemistry, Athens, Greece
- Corresponding authors.
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25
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Pestryaev EM. Chain Heterogeneity in Simulated Polymer Melts: Segment Orientational Autocorrelation Function. POLYMER SCIENCE SERIES A 2020. [DOI: 10.1134/s0965545x20060085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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26
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Tian L, Wu G. Microsecond molecular dynamics simulation of the adsorption and penetration of oil droplets on cellular membrane. JOURNAL OF HAZARDOUS MATERIALS 2020; 397:122683. [PMID: 32447203 DOI: 10.1016/j.jhazmat.2020.122683] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/15/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
The hazardous effects of petroleum contaminants in the soil and water environment are highly associated with their interactions with cellular membranes, but our understanding on the molecular-level mechanisms for the adsorption and penetration of heavy oil mixture on cellular membrane is very limited. In this study, microsecond molecular dynamics simulations were performed to gain insights into the morphological evolution and penetration dynamics of the multi-component and single-component oil droplets on the dipalmitoylphosphatidylcholine lipid membrane. Results highlighted the inhibition effect of the resins on the penetration of alkanes and aromatics, because they would form net structure making it difficult to release the latter two components from the oil droplet to the membrane. It also demonstrated the obviously different patterns of penetration between alkanes and aromatics. The overall steps for the toluene penetration included detachment from oil droplet, dispersion in water, adsorption on membrane surface, structure adjustment and penetration into membrane. By contrast, the step of dispersion in water was not necessary for the alkanes' penetration. Instead, it relied on the adsorption of the whole oil droplet on the membrane surface which resulted in the formation of pores on the membrane surface by local structure deformation in the lipid head group regions.
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Affiliation(s)
- Linqing Tian
- Division of Ocean Science and Technology, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China; School of Environment, Tsinghua University, Beijing, 100084, China
| | - Guozhong Wu
- Division of Ocean Science and Technology, Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China; School of Environment, Tsinghua University, Beijing, 100084, China.
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27
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Callahan KM, Mondou B, Sasseville L, Schwartz JL, D'Avanzo N. The influence of membrane bilayer thickness on KcsA channel activity. Channels (Austin) 2020; 13:424-439. [PMID: 31608774 PMCID: PMC6802934 DOI: 10.1080/19336950.2019.1676367] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Atomic resolution structures have provided significant insight into the gating and permeation mechanisms of various ion channels, including potassium channels. However, ion channels may also be regulated by numerous factors, including the physiochemical properties of the membrane in which they are embedded. For example, the matching of the bilayer's hydrophobic region to the hydrophobic external surface of the ion channel is thought to minimize the energetic penalty needed to solvate hydrophobic residues or exposed lipid tails. To understand the molecular basis of such regulation by hydrophobic matching requires examining channels in the presence of the lipid membrane. Here we examine the role of hydrophobic matching in regulating the activity of the model potassium channel, KcsA. 86Rb+ influx assays and single-channel recordings indicate that the non-inactivating E71A KcsA channel is most active in thin bilayers (<diC18:1PC). Bilayer thickness affects the open probability of KcsA and not its unitary conductance. Molecular dynamics simulations indicate that the bilayer can sufficiently modify its dimensions to accommodate KcsA channels without major perturbations in the protein helical packing within the nanosecond timescale. Based on experimental results and MD simulations, we present a model in which bilayer thickness influences the stability of the open and closed conformations of the intracellular gate of KcsA, with minimal impact on the stability of the selectivity filter of the non-inactivating mutant, E71A.
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Affiliation(s)
- Karen M Callahan
- From the Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal , Montréal , Canada
| | - Benoit Mondou
- Département de biochimie et médecine moléculaire, Université de Montréal , Montréal , Canada
| | - Louis Sasseville
- From the Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal , Montréal , Canada
| | - Jean-Louis Schwartz
- From the Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal , Montréal , Canada.,Département de biochimie et médecine moléculaire, Université de Montréal , Montréal , Canada.,Centre SÈVE, Université de Sherbrooke , Sherbrooke , Canada
| | - Nazzareno D'Avanzo
- From the Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal , Montréal , Canada.,Département de biochimie et médecine moléculaire, Université de Montréal , Montréal , Canada
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28
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Faulkner C, Santos-Carballal D, Plant DF, de Leeuw NH. Atomistic Molecular Dynamics Simulations of Propofol and Fentanyl in Phosphatidylcholine Lipid Bilayers. ACS OMEGA 2020; 5:14340-14353. [PMID: 32596571 PMCID: PMC7315410 DOI: 10.1021/acsomega.0c00813] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 05/29/2020] [Indexed: 06/11/2023]
Abstract
Atomistic molecular dynamics (MD) and steered MD simulations in combination with umbrella sampling methodology were utilized to study the general anesthetic propofol and the opioid analgesic fentanyl and their interaction with lipid bilayers, which is not yet fully understood. These molecules were inserted into two different fully hydrated phospholipid bilayers, namely, dioleoylphosphatidylcholine (DOPC) and dipalmitoylphosphatidylcholine (DPPC), to investigate the effects that these drugs have on the bilayer. We determined the role of the lipid chain length and saturation on the behavior of the two drugs. Pure, fully hydrated DOPC and DPPC bilayers were also simulated, and the results were in excellent agreement with the experimental values. Various structural and mechanical properties of each system, such as the area per lipid, area compressibility modulus, order parameter, lateral lipid diffusion, hydrogen bonds, and radial distribution functions, have been calculated to assess how the drug molecules affect the different bilayers. From the calculated results, we show that fentanyl and propofol generally follow similar trends in each bilayer but adopt different favorable positions close to the headgroup/chain interface at the carbonyl groups. Propofol was shown to selectively form hydrogen bonds at the carbonyl carbon in each bilayer, whereas fentanyl interacts with water molecules at the headgroup interface. From the calculated free-energy profiles, we determined that both molecules show a preference for the low-density, low-order acyl chain region of the bilayers and both significantly preferred the DOPC bilayer with propofol and fentanyl having energy minima at -6.66 and -43.07 kcal mol-1, respectively. This study suggests that different chain lengths and levels of saturation directly affect the properties of these two important molecules, which are seen to work together to control anesthesia in surgical applications.
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Affiliation(s)
- Christopher Faulkner
- School
of Chemistry, Cardiff University, Main Building, Park Place, CF10 3AT Cardiff, U.K.
| | - David Santos-Carballal
- School
of Chemistry, Cardiff University, Main Building, Park Place, CF10 3AT Cardiff, U.K.
- School
of Chemistry, University of Leeds, Leeds LS2 9JT, U.K.
| | | | - Nora H. de Leeuw
- School
of Chemistry, Cardiff University, Main Building, Park Place, CF10 3AT Cardiff, U.K.
- School
of Chemistry, University of Leeds, Leeds LS2 9JT, U.K.
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29
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Dazzoni R, Grélard A, Morvan E, Bouter A, Applebee CJ, Loquet A, Larijani B, Dufourc EJ. The unprecedented membrane deformation of the human nuclear envelope, in a magnetic field, indicates formation of nuclear membrane invaginations. Sci Rep 2020; 10:5147. [PMID: 32198481 PMCID: PMC7083927 DOI: 10.1038/s41598-020-61746-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/14/2020] [Indexed: 12/04/2022] Open
Abstract
Human nuclear membrane (hNM) invaginations are thought to be crucial in fusion, fission and remodeling of cells and present in many human diseases. There is however little knowledge, if any, about their lipid composition and dynamics. We therefore isolated nuclear envelope lipids from human kidney cells, analyzed their composition and determined the membrane dynamics after resuspension in buffer. The hNM lipid extract was composed of a complex mixture of phospholipids, with high amounts of phosphatidylcholines, phosphatidylinositols (PI) and cholesterol. hNM dynamics was determined by solid-state NMR and revealed that the lamellar gel-to-fluid phase transition occurs below 0 °C, reflecting the presence of elevated amounts of unsaturated fatty acid chains. Fluidity was higher than the plasma membrane, illustrating the dual action of Cholesterol (ordering) and PI lipids (disordering). The most striking result was the large magnetic field-induced membrane deformation allowing to determine the membrane bending elasticity, a property related to hydrodynamics of cells and organelles. Human Nuclear Lipid Membranes were at least two orders of magnitude more elastic than the classical plasma membrane suggesting a physical explanation for the formation of nuclear membrane invaginations.
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Affiliation(s)
- Régine Dazzoni
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France.,Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Axelle Grélard
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Estelle Morvan
- Institut Européen de Chimie et Biologie, UMS3033, CNRS, Université Bordeaux, INSERM (US001), 2 rue Escarpit, Pessac, 33600, France
| | - Anthony Bouter
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Christopher J Applebee
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain.,Cell Biophysics Laboratory, Centre for Therapeutic Innovation & Department of Pharmacy and Pharmacology, & Department of Physics, University of Bath, Bath, United Kingdom
| | - Antoine Loquet
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain. .,Cell Biophysics Laboratory, Centre for Therapeutic Innovation & Department of Pharmacy and Pharmacology, & Department of Physics, University of Bath, Bath, United Kingdom.
| | - Erick J Dufourc
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France.
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30
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Park S, Yeom MS, Andersen OS, Pastor RW, Im W. Quantitative Characterization of Protein-Lipid Interactions by Free Energy Simulation between Binary Bilayers. J Chem Theory Comput 2019; 15:6491-6503. [PMID: 31560853 PMCID: PMC7076909 DOI: 10.1021/acs.jctc.9b00815] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using a recently developed binary bilayer system (BBS) consisting of two patches of laterally contacting bilayers, umbrella sampling molecular dynamics (MD) simulations were performed for quantitative characterization of protein-lipid interactions. The BBS is composed of 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) with an embedded model membrane protein, a gramicidin A (gA) channel. The calculated free energy difference for the transfer of a gA channel from DLPC (hydrophobic thickness ≈ 21.5 Å) to DMPC (hydrophobic thickness ≈ 25.5 Å) bilayers, ΔG(DLPC → DMPC), is -2.2 ± 0.7 kcal/mol. This value appears at odds with the traditional view that the hydrophobic length of the gA channel is ∼22 Å. To understand this discrepancy, we first note that recent MD simulations by different groups have shown that lipid bilayer thickness profiles in the vicinity of a gA channel differ qualitatively from the deformation profile predicted from continuum elastic bilayer models. Our MD simulations at low and high gA:lipid molar ratios and different membrane compositions indicate that the gA channel's effective hydrophobic length is ∼26 Å. Using this effective hydrophobic length, ΔG(DLPC → DMPC) determined here is in excellent agreement with predictions based on continuum elastic models (-3.0 to -2.2 kcal/mol) where the bilayer deformation energy is approximated as a harmonic function of the mismatch between the channel's effective hydrophobic length and the hydrophobic thickness of the bilayer. The free energy profile for gA in the BBS includes a barrier at the interface between the two bilayers which can be attributed to the line tension at the interface between two bilayers with different hydrophobic thicknesses. This observation implies that translation of a peptide between two different regions of a cell membrane (such as between the liquid ordered and disordered phases) may include effects of a barrier at the interface in addition to the relative free energies of the species far from the interface. The BBS allows for direct transfer free energy calculations between bilayers without a need of a reference medium, such as bulk water, and thus provides an efficient simulation protocol for the quantitative characterization of protein-lipid interactions at all-atom resolution.
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Affiliation(s)
- Soohyung Park
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States
| | - Min Sun Yeom
- Korean Institute of Science and Technology Information , Daejeon , Korea
| | - Olaf S Andersen
- Department of Physiology and Biophysics , Weill Cornell Medicine , New York , New York 10065 , United States
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Wonpil Im
- Departments of Biological Sciences and Bioengineering , Lehigh University , Bethlehem , Pennsylvania 18015 , United States.,School of Computational Sciences , Korea Institute for Advanced Study , Seoul 02455 , Republic of Korea
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31
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Münzberg E, Stein M. Structure and Dynamics of Mono- vs. Doubly Lipidated Rab5 in Membranes. Int J Mol Sci 2019; 20:ijms20194773. [PMID: 31561436 PMCID: PMC6801778 DOI: 10.3390/ijms20194773] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/25/2019] [Accepted: 09/25/2019] [Indexed: 01/13/2023] Open
Abstract
The Rab5 small GTPase is a regulator of endosomal trafficking and vesicle fusion. It possesses two adjacent cysteine residues for post-translational geranylgeranylation at its C-terminus for the protein to associate with the early endosome membrane. We compare the effect of mono-lipidification of only one cysteine residue with the doubly modified, fully functional Rab protein in both guanosine diphosphate (GDP)- and guanosine triphosphate (GTP)-bound states and in different membranes (one, three, and six-component membranes). Molecular simulations show that the mono-geranylgeranylated protein is less strongly associated with the membranes and diffuses faster than the doubly lipidated protein. The geranylgeranyl anchor membrane insertion depth is smaller and the protein–membrane distance distribution is broad and uncharacteristic for the membrane composition. The mono-geranylgeranylated protein reveals an unspecific association with the membrane and an orientation at the membrane that does not allow a nucleotide-specific recruitment of further effector proteins. This work shows that double-lipidification is critical for Rab5 to perform its physiological function and mono-geranylgeranylation renders it membrane-associated but non-functional.
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Affiliation(s)
- Eileen Münzberg
- Max Planck Institute for Dynamics of Complex Technical Systems, Molecular Simulations and Design Group, Sandtorstrasse 1, 39106 Magdeburg, Germany.
| | - Matthias Stein
- Max Planck Institute for Dynamics of Complex Technical Systems, Molecular Simulations and Design Group, Sandtorstrasse 1, 39106 Magdeburg, Germany.
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32
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Marzuoli I, Margreitter C, Fraternali F. Lipid Head Group Parameterization for GROMOS 54A8: A Consistent Approach with Protein Force Field Description. J Chem Theory Comput 2019; 15:5175-5193. [PMID: 31433640 PMCID: PMC7377650 DOI: 10.1021/acs.jctc.9b00509] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
Membranes
are a crucial component of both bacterial and mammalian
cells, being involved in signaling, transport, and compartmentalization.
This versatility requires a variety of lipid species to tailor the
membrane’s behavior as needed, increasing the complexity of
the system. Molecular dynamics simulations have been successfully
applied to study model membranes and their interactions with proteins,
elucidating some crucial mechanisms at the atomistic detail and thus
complementing experimental techniques. An accurate description of
the functional interplay of the diverse membrane components crucially
depends on the selected parameters that define the adopted force field.
A coherent parameterization for lipids and proteins is therefore needed.
In this work, we propose and validate new lipid head group parameters
for the GROMOS 54A8 force field, making use of recently published
parametrizations for key chemical moieties present in lipids. We make
use additionally of a new canonical set of partial charges for lipids,
chosen to be consistent with the parameterization of soluble molecules
such as proteins. We test the derived parameters on five phosphocholine
model bilayers, composed of lipid patches four times larger than the
ones used in previous studies, and run 500 ns long simulations of
each system. Reproduction of experimental data like area per lipid
and deuterium order parameters is good and comparable with previous
parameterizations, as well as the description of liquid crystal to
gel-phase transition. On the other hand, the orientational behavior
of the head groups is more realistic for this new parameter set, and
this can be crucial in the description of interactions with other
polar molecules. For that reason, we tested the interaction of the
antimicrobial peptide lactoferricin with two model membranes showing
that the new parameters lead to a weaker peptide–membrane binding
and give a more realistic outcome in comparing binding to antimicrobial
versus mammal membranes.
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Affiliation(s)
- Irene Marzuoli
- Randall Centre for Cell and Molecular Biology , King's College London , London SE1 1UL , U.K
| | - Christian Margreitter
- Randall Centre for Cell and Molecular Biology , King's College London , London SE1 1UL , U.K
| | - Franca Fraternali
- Randall Centre for Cell and Molecular Biology , King's College London , London SE1 1UL , U.K
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33
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Rózsa ZB, Németh LJ, Jójárt B, Nehéz K, Viskolcz B, Szőri M. Molecular Dynamics and Metadynamics Insights of 1,4-Dioxane-Induced Structural Changes of Biomembrane Models. J Phys Chem B 2019; 123:7869-7884. [DOI: 10.1021/acs.jpcb.9b04313] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Zsófia Borbála Rózsa
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - Lukács József Németh
- Department of Food Engineering, Faculty of Engineering, University of Szeged, Mars tér 7, 6724 Szeged, Hungary
| | - Balázs Jójárt
- Department of Food Engineering, Faculty of Engineering, University of Szeged, Mars tér 7, 6724 Szeged, Hungary
| | - Károly Nehéz
- Department of Information Engineering, University of Miskolc, Miskolc-Egyetemváros Informatics Building, H-3515 Miskolc, Hungary
| | - Béla Viskolcz
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - Milán Szőri
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
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Kruczek J, Chiu SW, Varma S, Jakobsson E, Pandit SA. Interactions of Monovalent and Divalent Cations at Palmitoyl-Oleoyl-Phosphatidylcholine Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10522-10532. [PMID: 31337218 DOI: 10.1021/acs.langmuir.9b01275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Li+ is a biologically active and medically important cation. Experiments show that Li+ modulates some phospholipid bilayer properties in a manner similar to divalent cations, rather than other monovalent cations. We previously performed a comparative simulation study of the interaction of several monovalent cations with palmitoyl-oleoyl-phosphatidylcholine bilayers and reported that Li+ exhibited the highest association with lipids and formed a unique tetrahedral coordinated structure with lipid head groups. Here we extend these studies to two biologically important divalent cations, Mg2+ and Ca2+, and observe that, just like monovalent cations, Mg2+ and Ca2+ reduce bilayer areas and increase chain order. Bilayer area changes induced by cations are strongly correlated with the amount of charge inside the headgroup region; however, Mg2+ and Li+ are clear outliers. At the same time though, Mg2+ adsorption in the bilayer is the smallest among all cations, which is in contrast to Li+ that binds strongly to lipids. In fact, in contrast to all other cations, Mg2+ remains fully hydrated in the lipid headgroup region. However, Li+ and Mg2+ share high overlap between their inner-shell coordination topologies. This suggests that Li+ can structurally replace Mg2+, which is bound to other biomolecules with up to fourfold coordination, provided such replacement is energetically feasible. We compute structural topologies and compare them quantitatively using a new weighted-graphs-based method. Finally, we find that the specificity of cation interaction with lipid head groups exhibit consistent trend with the solvation shell energetics of ions in lipid headgroup and bulk water regions.
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Hassan PA, Gawali SL. Directing Amphiphilic Self-Assembly: From Microstructure Control to Interfacial Engineering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:9635-9646. [PMID: 30392370 DOI: 10.1021/acs.langmuir.8b02921] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The self-assembly of small molecules into complex nanoscale structures is driven by the interplay of various noncovalent interactions. It has now become evident that by maneuvering this intermolecular interaction the geometry and interfacial properties of several nanoscale objects can be tamed. In particular, diverse structures such as spheres, rods, worms, ribbons, and vesicles can be produced by tuning the packing of molecules in the aggregate. Stimuli-sensitive assemblies that can reversibly associate or dissociate in response to environmental changes have been fabricated as model systems for the self-regulated drug delivery vehicle. Surface passivation of inorganic materials can be achieved by the selective organization of molecules at the interface. Such surface functionalization of inorganic materials by organic counterparts provides kinetic stability in biological media and permits the selective binding of active ingredients. Advances made in the area of molecular self-assembly and factors governing such association processes have made it possible to control the interfacial properties and microstructure of nanoscale materials.
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Affiliation(s)
- Puthusserickal Abdulrahiman Hassan
- Chemistry Division , Bhabha Atomic Research Centre , Trombay, Mumbai 400 085 , India
- Homi Bhabha National Institute, Training School Complex , Anushaktinagar, Mumbai 400 094 , India
| | - Santosh L Gawali
- Chemistry Division , Bhabha Atomic Research Centre , Trombay, Mumbai 400 085 , India
- Homi Bhabha National Institute, Training School Complex , Anushaktinagar, Mumbai 400 094 , India
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36
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Effects of Cholesterol on Water Permittivity of Biomimetic Ion Pair Amphiphile Bilayers: Interplay between Membrane Bending and Molecular Packing. Int J Mol Sci 2019; 20:ijms20133252. [PMID: 31269714 PMCID: PMC6651711 DOI: 10.3390/ijms20133252] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 06/28/2019] [Accepted: 06/28/2019] [Indexed: 02/04/2023] Open
Abstract
Ion pair amphiphile (IPA), a molecular complex composed of a pair of cationic and anionic amphiphiles, is an inexpensive phospholipid substitute to fabricate vesicles with various pharmaceutical applications. Modulating the physicochemical and permeation properties of IPA vesicles are important for carrier designs. Here, we applied molecular dynamics simulations to examine the cholesterol effects on the structures, mechanics, and water permittivity of hexadecyltrimethylammonium-dodecylsulfate (HTMA-DS) and dodecyltrimethylammonium- hexadecylsulfate (DTMA-HS) IPA bilayers. Structural and mechanical analyses indicate that both IPA systems are in gel phase at 298 K. Adding cholesterol induces alkyl chain ordering around the rigid sterol ring and increases the cavity density within the hydrophilic region of both IPA bilayers. Furthermore, the enhanced alkyl chain ordering and the membrane deformation energy induced by cholesterol increase the permeation free energy penalty. In contrast, cholesterol has minor effects on the water local diffusivities within IPA membranes. Overall, the cholesterol reduces the water permittivity of rigid IPA membranes due to the synergistic effects of increased alkyl chain ordering and enhanced membrane mechanical modulus. The results provide molecular insights into the effects of molecular packing and mechanical deformations on the water permittivity of biomimetic IPA membranes, which is critical for designing IPA vesicular carriers.
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Saunders M, Steele M, Lavigne W, Varma S, Pandit SA. Interaction of salt with ether- and ester-linked phospholipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:907-915. [PMID: 30742804 DOI: 10.1016/j.bbamem.2019.01.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/14/2019] [Accepted: 01/28/2019] [Indexed: 10/27/2022]
Abstract
A distinguishing feature of Archaeal plasma membranes is that their phospholipids contain ether-links, as opposed to bacterial and eukaryotic plasma membranes where phospholipids primarily contain ester-links. Experiments show that this chemical difference in headgroup-tail linkage does produce distinct differences in model bilayer properties. Here we examine the effects of salt on bilayer structure in the case of an ether-linked lipid bilayer. We use molecular dynamics simulations and compare equilibrium properties of two model lipid bilayers in NaCl salt solution - POPC and its ether-linked analog that we refer to as HOPC. We make the following key observations. The headgroup region of HOPC "adsorbs" fewer ions compared to the headgroup region of POPC. Consistent with this, we note that the Debye screening length in the HOPC system is ∼ 10% shorter than that in the POPC system. Herein, we introduce a protocol to identify the lipid-water interfacial boundary that reproduces the bulk salt distribution consistent with Gouy-Chapman theory. We also note that the HOPC bilayer has excess solvent in the headgroup region when compared to POPC, coinciding with a trough in the electrostatic potential. Waters in this region have longer autocorrelation times and smaller lateral diffusion rates compared to the corresponding region in the POPC bilayer, suggesting that the waters in HOPC are more strongly coordinated to the lipid headgroups. Furthermore, we note that it is this region of tightly coordinated waters in the HOPC system that has a lower density of Na+ ions. Based on these observations we conclude that an ether-linked lipid bilayer has a lower binding affinity for Na+ compared to an ester-linked lipid bilayer.
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Affiliation(s)
- Matthew Saunders
- Department of Cell biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, United States of America.
| | - Mark Steele
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | - Wyatt Lavigne
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | - Sameer Varma
- Department of Cell biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, United States of America; Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
| | - Sagar A Pandit
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America.
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38
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Oroskar PA, Jameson CJ, Murad S. Molecular-Level "Observations" of the Behavior of Gold Nanoparticles in Aqueous Solution and Interacting with a Lipid Bilayer Membrane. Methods Mol Biol 2019; 2000:303-359. [PMID: 31148024 DOI: 10.1007/978-1-4939-9516-5_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We use coarse-grained molecular dynamics simulations to "observe" details of interactions between ligand-covered gold nanoparticles and a lipid bilayer model membrane. In molecular dynamics simulations, one puts the individual atoms and groups of atoms of the physical system to be "observed" into a simulation box, specifies the forms of the potential energies of interactions between them (ultimately quantum based), and lets them individually move classically according to Newton's equations of motion, based on the forces arising from the assumed potential energy forms. The atoms that are chemically bonded to each other stay chemically bonded, following known potentials (force fields) that permit internal degrees of freedom (internal rotation, torsion, vibrations), and the interactions between nonbonded atoms are simplified to Lennard-Jones forms (in our case) and coulombic (where electrical charges are present) in which the parameters are previously optimized to reproduce thermodynamic properties or are based on quantum electronic calculations. The system is started out at a reasonable set of coordinates for all atoms or groups of atoms, and then permitted to develop according to the equations of motion, one small step (usually 10 fs time step) at a time, for millions of steps until the system is at a quasi-equilibrium (usually reached after hundreds of nanoseconds). We then let the system play out its motions further for many nanoseconds to observe the behavior, periodically taking snapshots (saving all positions and energies), and post-processing the snapshots to obtain various average descriptions of the system. Alkanethiols of various lengths serve as examples of hydrophobic ligands and methyl-terminated PEG with various numbers of monomer units serve as examples of hydrophilic ligands. Spherical gold particles of various diameters as well as gold nanorods form the core to which ligands are attached. The nanoparticles are characterized at the molecular level, especially the distributions of ligand configurations and their dependence on ligand length, and surface coverage. Self-assembly of the bilayer from an isotropic solution and observation of membrane properties that correspond well to experimental values validate the simulations. The mechanism of permeation of a gold NP coated with either a hydrophobic or a hydrophilic ligand, and its dependence on surface coverage, ligand length, core diameter, and core shape, is investigated. Lipid response such as lipid flip-flops, lipid extraction, and changes in order parameter of the lipid tails are examined in detail. The mechanism of permeation of a PEGylated nanorod is shown to occur by tilting, lying down, rotating, and straightening up. The nature of the information provided by molecular dynamics simulations permits understanding of the detailed behavior of gold nanoparticles interacting with lipid membranes which in turn helps to understand why some known systems work better than others and aids the design of new particles and improvement of methods for preparing existing ones.
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Affiliation(s)
- Priyanka A Oroskar
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Cynthia J Jameson
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA
| | - Sohail Murad
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL, USA.
- Department of Chemical Engineering, Illinois Institute of Technology, Chicago, IL, USA.
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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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40
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Leeb F, Maibaum L. Spatially Resolving the Condensing Effect of Cholesterol in Lipid Bilayers. Biophys J 2018; 115:2179-2188. [PMID: 30447996 DOI: 10.1016/j.bpj.2018.10.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 10/15/2018] [Accepted: 10/24/2018] [Indexed: 11/15/2022] Open
Abstract
We study the effect of cholesterol on the structure of dipalmitoylphosphatidylcholine phospholipid bilayers. Using extensive molecular dynamics computer simulations at atomistic resolution, we observe and quantify several structural changes upon increasing cholesterol content that are collectively known as the condensing effect: a thickening of the bilayer, an increase in lipid tail order, and a decrease in lateral area. We also observe a change in leaflet interdigitation and a lack thereof in the distributions of dipalmitoylphosphatidylcholine headgroup orientations. These results, obtained over a wide range of cholesterol mole fractions, are then used to calibrate the analysis of phospholipid properties in bilayers containing a single cholesterol molecule per leaflet, which we perform in a spatially resolved way. We find that a single cholesterol molecule affects phospholipids in its first and second solvation shells, which puts the range of this effective interaction to be on the order of 1-2 nm. We also observe a tendency of phospholipids to orient their polar headgroups toward the cholesterol, which provides additional support for the umbrella model of bilayer organization.
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Affiliation(s)
- Felix Leeb
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Lutz Maibaum
- Department of Chemistry, University of Washington, Seattle, Washington.
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41
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Lipid-Mediated Interactions between the Antimicrobial Peptides Magainin 2 and PGLa in Bilayers. Biophys J 2018; 115:1033-1044. [PMID: 30195937 DOI: 10.1016/j.bpj.2018.08.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 07/13/2018] [Accepted: 08/06/2018] [Indexed: 01/02/2023] Open
Abstract
A synergistic enhancement of activities has been described for the amphipathic cationic antimicrobial peptides magainin 2 and PGLa when tested in antimicrobial assays or in biophysical experiments using model membranes. In the presence of magainin 2, PGLa changes from an in-planar alignment parallel to the membrane surface to a more transmembrane orientation when investigated in membranes made from fully saturated PC or PC/PG, but not when one of the fatty acyl chains is unsaturated. Such lipid-mediated changes in the membrane topology of polypeptide domains could provide an interesting mechanism for the regulation of membrane proteins. Here we investigated the PGLa topology in a wide variety of membranes made of saturated or unsaturated PE, PC, and/or PG using 15N solid-state NMR spectroscopy. In contrast to predictions made by previous models the data show that membrane curvature has only a minor effect on PGLa realignment. Furthermore, using 2H solid-state NMR spectroscopy of deuterated phospholipid fatty acyl chains the order parameters of the lipids were investigated in the presence of PGLa, magainin, or equimolar peptide mixtures. Both peptides cause a pronounced decrease in the order parameters when oriented parallel to the membrane surface, an effect that reverts when PGLa flips into transmembrane alignments. Taken together, these data are suggestive that the magainin-induced disordering of fatty acyl chains provides an important driving force for PGLa realignment.
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42
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Sajadi F, Rowley CN. Simulations of lipid bilayers using the CHARMM36 force field with the TIP3P-FB and TIP4P-FB water models. PeerJ 2018; 6:e5472. [PMID: 30128211 PMCID: PMC6097494 DOI: 10.7717/peerj.5472] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/28/2018] [Indexed: 12/13/2022] Open
Abstract
The CHARMM36 force field for lipids is widely used in simulations of lipid bilayers. The CHARMM family of force fields were developed for use with the mTIP3P water model. This water model has an anomalously high dielectric constant and low viscosity, which limits its accuracy in the calculation of quantities like permeability coefficients. The TIP3P-FB and TIP4P-FB water models are more accurate in terms of the dielectric constant and transport properties, which could allow more accurate simulations of systems containing water and lipids. To test whether the CHARMM36 lipid force field is compatible with the TIP3P-FB and TIP4P-FB water models, we have performed simulations of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers. The calculated headgroup area, compressibility, order parameters, and X-ray form factors are in good agreement with the experimental values, indicating that these improved water models can be used with the CHARMM36 lipid force field without modification when calculating membrane physical properties. The water permeability predicted by these models is significantly different; the mTIP3P-model diffusion in solution and at the lipid-water interface is anomalously fast due to the spuriously low viscosity of mTIP3P-model water, but the potential of mean force of permeation is higher for the TIP3P-FB and TIP4P-FB models due to their high excess chemical potentials. As a result, the rates of water permeation calculated the FB water models are slower than the experimental value by a factor of 15-17, while simulations with the mTIP3P model only underestimate the water permeability by a factor of 3.
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Affiliation(s)
- Fatima Sajadi
- Department of Chemistry, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Christopher N Rowley
- Department of Chemistry, Memorial University of Newfoundland, St. John's, NL, Canada
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43
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Pestryaev EM. Oscillating Free Induction Decay in Polymer Systems: Theoretical Analysis. POLYMER SCIENCE SERIES A 2018. [DOI: 10.1134/s0965545x18040090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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44
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Azar E, Constantin D, Warschawski DE. The effect of gramicidin inclusions on the local order of membrane components. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:44. [PMID: 29582214 PMCID: PMC7088371 DOI: 10.1140/epje/i2018-11644-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 03/07/2018] [Indexed: 06/08/2023]
Abstract
We study the local effect of the antimicrobial peptide Gramicidin A on bilayers composed of lipids or surfactants using nuclear magnetic resonance spectroscopy and wide-angle X-ray scattering, techniques that probe the orientational and positional order of the alkyl chains, respectively. The two types of order vary with temperature and peptide concentration in complex ways which depend on the membrane composition, highlighting the subtlety of the interaction between inclusions and the host bilayer. The amplitude of the variation is relatively low, indicating that the macroscopic constants used to describe the elasticity of the bilayer are unlikely to change with the addition of peptide.
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Affiliation(s)
- Elise Azar
- Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405, Orsay Cedex, France
| | - Doru Constantin
- Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405, Orsay Cedex, France.
| | - Dror E Warschawski
- UMR 7099, CNRS-Université Paris Diderot, Institut de Biologie Physico-Chimique, Paris, France
- Département de Chimie, Université du Québec à Montréal, Downtown Station, P.O. Box 8888, H3C 3P8, Montreal, Canada
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45
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Lyu Y, Xiang N, Mondal J, Zhu X, Narsimhan G. Characterization of Interactions between Curcumin and Different Types of Lipid Bilayers by Molecular Dynamics Simulation. J Phys Chem B 2018; 122:2341-2354. [PMID: 29394060 DOI: 10.1021/acs.jpcb.7b10566] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Yuan Lyu
- Department of Agricultural
and Biological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ning Xiang
- Department of Agricultural
and Biological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jagannath Mondal
- Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 36/P, Gopanapally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500107, India
| | - Xiao Zhu
- Research
Computing, Rosen Center for Advanced Computing, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ganesan Narsimhan
- Department of Agricultural
and Biological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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46
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Fei Q, Kent D, Botello-Smith WM, Nur F, Nur S, Alsamarah A, Chatterjee P, Lambros M, Luo Y. Molecular Mechanism of Resveratrol's Lipid Membrane Protection. Sci Rep 2018; 8:1587. [PMID: 29371621 PMCID: PMC5785473 DOI: 10.1038/s41598-017-18943-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 12/19/2017] [Indexed: 11/09/2022] Open
Abstract
Resveratrol, a natural compound found in red wine and various vegetables, has drawn increasing interest due to its reported benefit in cardiovascular protection, neurodegenerative disorders, and cancer therapy. The mechanism by which resveratrol exerts such pleiotropic effects remains unclear. It remains as one of the most discussed polyphenol compounds in the debating "French Paradox". In this study, using molecular dynamics simulations of dipalmitoyl phosphatidylcholine (DPPC) bilayer with resveratrol, we generated a free energy map of resveratrol's location and orientation of inside the lipid bilayer. We found that resveratrol increases the surface area per lipid and decreases membrane thickness, which is the opposite effect of the well-studied cholesterol on liquid phase DPPC. Most importantly, based on the simulation observation that resveratrol has a high probability of forming hydrogen bonds with sn-1 and sn-2 ester groups, we discovered a new mechanism using experimental approach, in which resveratrol protects both sn-1 and sn-2 ester bonds of DPPC and distearoyl phosphatidylcholine (DSPC) from phospholipase A1 (PLA1) and phospholipase A2 (PLA2) cleavage. Our study elucidates the new molecular mechanism of potential health benefits of resveratrol and possibly other similar polyphenols and provides a new paradigm for drug design based on resveratrol and its analogs.
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Affiliation(s)
- Qinqin Fei
- Western University of Health Sciences, College of pharmacy, Pomona, CA, 91766, USA
| | - David Kent
- Western University of Health Sciences, College of pharmacy, Pomona, CA, 91766, USA
| | | | - Fariah Nur
- Western University of Health Sciences, College of pharmacy, Pomona, CA, 91766, USA
| | - Saadia Nur
- Western University of Health Sciences, College of pharmacy, Pomona, CA, 91766, USA
| | - Abdelaziz Alsamarah
- Western University of Health Sciences, College of pharmacy, Pomona, CA, 91766, USA
| | - Payal Chatterjee
- Western University of Health Sciences, College of pharmacy, Pomona, CA, 91766, USA
| | - Maria Lambros
- Western University of Health Sciences, College of pharmacy, Pomona, CA, 91766, USA.
| | - Yun Luo
- Western University of Health Sciences, College of pharmacy, Pomona, CA, 91766, USA.
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47
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Coimbra JTS, Brás NF, Fernandes PA, Rangel M, Ramos MJ. Membrane partition of bis-(3-hydroxy-4-pyridinonato) zinc(ii) complexes revealed by molecular dynamics simulations. RSC Adv 2018; 8:27081-27090. [PMID: 35539964 PMCID: PMC9083369 DOI: 10.1039/c8ra03602k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 07/23/2018] [Indexed: 12/24/2022] Open
Abstract
The class of 3-hydroxy-4-pyridinone ligands is widely known and valuable for biomedical and pharmaceutical purposes. Their chelating properties towards biologically-relevant transition metal ions highlight their potential biomedical utility. A set of 3-hydroxy-4-pyridinone Zn(ii) complexes at different concentrations was studied for their ability to interact with lipid phases. We employed umbrella sampling simulations to attain the potential-of-mean force for a set of ligands and one Zn(ii) complex, as these permeated a 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) hydrated bilayer system. In addition, we used conventional molecular dynamics simulations to study the behavior of various Zn(ii) complexes in hydrated bilayer systems. This work discusses: (i) the partition of 3-hydroxy-4-pyridinone ligands to bilayer phases; (ii) self-aggregation in crowded environments of Zn(ii) complexes; and (iii) possible mechanisms for the membrane translocation of Zn(ii) complexes. We observed distinct interactions for the studied complexes, and distinct membrane partition coefficients (Kmem) depending on the considered ligand. The more hydrophobic ligand, 1-hexyl-3-hydroxy-2-methyl-4(1H)-pyridinone, partitioned more favorably to lipid phases (at least two orders of magnitude higher Kmem when compared to the other ligands), and the corresponding Zn(ii) complex was also prone to self-aggregation when an increased concentration of the complex was employed. We also observed that the inclusion of a coordinated water molecule in the parameterization of the Zn(ii) coordination sphere, as proposed in the available crystallographic structure of the complex, decreased the partition coefficient and membrane permeability for the tested complex. The membrane partition of hydroxypyridinones and of zinc complexes explored by molecular dynamics.![]()
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Affiliation(s)
- João T. S. Coimbra
- UCIBIO
- REQUIMTE
- Departamento de Química e Bioquímica
- Faculdade de Ciências
- Universidade do Porto
| | - Natércia F. Brás
- UCIBIO
- REQUIMTE
- Departamento de Química e Bioquímica
- Faculdade de Ciências
- Universidade do Porto
| | - Pedro A. Fernandes
- UCIBIO
- REQUIMTE
- Departamento de Química e Bioquímica
- Faculdade de Ciências
- Universidade do Porto
| | - Maria Rangel
- LAQV
- REQUIMTE
- Instituto de Ciências Biomédicas de Abel Salazar
- Universidade do Porto
- 4050-313 Porto
| | - Maria J. Ramos
- UCIBIO
- REQUIMTE
- Departamento de Química e Bioquímica
- Faculdade de Ciências
- Universidade do Porto
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48
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Hien Nguyen T, C. Moore C, B. Moore P, Liu Z. Molecular dynamics study of homo-oligomeric ion channels: Structures of the surrounding lipids and dynamics of water movement. AIMS BIOPHYSICS 2018. [DOI: 10.3934/biophy.2018.1.50] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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49
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Shaghaghi M, Keyvanloo A, Huang Z, Szoka FC, Thewalt JL. Constrained Versus Free Cholesterol in DPPC Membranes: A Comparison of Chain Ordering Ability Using Deuterium NMR. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:14405-14413. [PMID: 29120186 DOI: 10.1021/acs.langmuir.7b03299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report here the first exploration of the nature of the hydrophobic region of bilayer membranes formed from sterol-modified phospholipids [Huang, Z.; Szoka, F. C., Sterol-Modified Phospholipids: Cholesterol and Phospholipid Chimeras with Improved Biomembrane Properties. J. Am. Chem. Soc. 2008, 130 (46), 15702-15712] & [Ding, J.; Starling, A. P.; East, J. M.; Lee, A. G., Binding Sites for Cholesterol on Ca(2+)-ATPase Studied by Using a Cholesterol-Containing Phospholipid. Biochemistry 1994, 33 (16), 4974-4979]. Using 2H NMR spectroscopy, we present our results for the phase behavior and acyl chain ordering of multilamellar vesicles (MLVs) of a sterol-modified phospholipid, 1-cholesterylhemisuccinoyl-2-palmitoyl(d31)-sn-glycero-3-phosphocholine (hereafter referred to as CholPPC-d31). We compared our results with the conformational order induced by cholesterol at various concentrations in 1-palmitoyl,2-palmitoyl(d31)-sn-glycero-3-phosphocholine (DPPC-d31)/cholesterol membranes. On the basis of the existing literature [Foglia, F.; Barlow, D. J.; Szoka, F. C.; Huang, Z.; Rogers, S. E.; Lawrence, M. J., Structural Studies of the Monolayers and Bilayers Formed by a Novel Cholesterol-Phospholipid Chimera. Langmuir 2011, 27 (13), 8275-8281], we expected to find that the deuterated palmitoyl chain in CholPPC-d31 membranes had an order parameter profile similar to the deuterated palmitoyl chain of sn-2 labeled DPPC-d31 in MLVs of a mixture of DPPC-d31 with 40 mol % unconstrained cholesterol. Our data indicate that the ordering ability of cholesterol in CholPPC is significantly reduced compared to free cholesterol in DPPC. This result emphasizes that cholesterol molecules must be free to move in the bilayers to reach their maximum ordering ability. In other words, when compared to unconstrained cholesterol, the constrained cholesterol moiety in CholPPC causes nonoptimal chain packing.
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Affiliation(s)
| | | | - Zhaohua Huang
- Merrimack Pharmaceuticals , One Kendall Square, Suite B7201, Cambridge, Massachusetts 02139, United States
| | - Francis C Szoka
- Department of Bioengineering and Therapeutic Sciences, School of Pharmacy, University of California , San Francisco, California 94143, United States
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50
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Loffredo MR, Ghosh A, Harmouche N, Casciaro B, Luca V, Bortolotti A, Cappiello F, Stella L, Bhunia A, Bechinger B, Mangoni ML. Membrane perturbing activities and structural properties of the frog-skin derived peptide Esculentin-1a(1-21)NH2 and its Diastereomer Esc(1-21)-1c: Correlation with their antipseudomonal and cytotoxic activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2327-2339. [DOI: 10.1016/j.bbamem.2017.09.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 08/21/2017] [Accepted: 09/08/2017] [Indexed: 01/21/2023]
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