1
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Shimokawa N, Hamada T. Physical Concept to Explain the Regulation of Lipid Membrane Phase Separation under Isothermal Conditions. Life (Basel) 2023; 13:life13051105. [PMID: 37240749 DOI: 10.3390/life13051105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/21/2023] [Accepted: 04/22/2023] [Indexed: 05/28/2023] Open
Abstract
Lateral phase separation within lipid bilayer membranes has attracted considerable attention in the fields of biophysics and cell biology. Living cells organize laterally segregated compartments, such as raft domains in an ordered phase, and regulate their dynamic structures under isothermal conditions to promote cellular functions. Model membrane systems with minimum components are powerful tools for investigating the basic phenomena of membrane phase separation. With the use of such model systems, several physicochemical characteristics of phase separation have been revealed. This review focuses on the isothermal triggering of membrane phase separation from a physical point of view. We consider the free energy of the membrane that describes lateral phase separation and explain the experimental results of model membranes to regulate domain formation under isothermal conditions. Three possible regulation factors are discussed: electrostatic interactions, chemical reactions and membrane tension. These findings may contribute to a better understanding of membrane lateral organization within living cells that function under isothermal conditions and could be useful for the development of artificial cell engineering.
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Affiliation(s)
- Naofumi Shimokawa
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi 923-1292, Ishikawa, Japan
| | - Tsutomu Hamada
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi 923-1292, Ishikawa, Japan
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2
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Ramírez-Garza OA, Méndez-Alcaraz JM, González-Mozuelos P. Effects of the curvature gradient on the distribution and diffusion of colloids confined to surfaces. Phys Chem Chem Phys 2021; 23:8661-8672. [PMID: 33876027 DOI: 10.1039/d0cp06474b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The properties and behavior of colloids confined to move on curved surfaces offer a fertile ground for analysis since the geometric constraints induce specific features that are not available in flat spaces. Given their pertinence for biological and physicochemical processes, both with potential useful applications, the development of the concepts and methodology necessary for a deeper understanding of these unconventional systems is indeed an essential pursuit. The present study discusses a general and rigorous algorithm for the implementation of Brownian dynamics simulations that solves underlying difficulties and shortcomings inherent to conventional first-order schemes. Still based on the Ermak-McCammon recipe, our approach complements it with the higher-order geodesical projections of the elementary jumps generated on the associated tangent plane. This strategy, which warrants the locally isotropic propagation of non-interacting particles, is tested with a model system of colloidal particles interacting through a screened Coulomb potential while confined to move on ellipsoidal surfaces. This allows us to measure the effects prompted by the curvature gradient on the static and dynamic properties of this system. The varying curvature thus induces energetically favorable configurations in which the particles maximize their Euclidean distancing by crowding the regions with the largest Gaussian curvature, while withdrawing from those with the lowest. In turn, these inhomogeneous distributions provoke the anisotropic self-diffusion of the confined colloids, which is examined by exploiting the pertinent geodesic radial coordinates. The proficient methods under consideration thus allows dealing with the rich and remarkable new phenomena generated by any distinctive surface geometry.
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Affiliation(s)
- O A Ramírez-Garza
- Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, Ciudad de México, C. P. 07360, Mexico.
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3
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Xin W, Wu H, Grason GM, Santore MM. Switchable positioning of plate-like inclusions in lipid membranes: Elastically mediated interactions of planar colloids in 2D fluids. SCIENCE ADVANCES 2021; 7:eabf1943. [PMID: 33811075 PMCID: PMC11057706 DOI: 10.1126/sciadv.abf1943] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
We demonstrate how manipulating curvature in an elastic fluid lamella enables the reversible relative positioning of flat, rigid, plate-like micrometer-scale inclusions, with spacings from about a micrometer to tens of micrometers. In an experimental model comprising giant unilamellar vesicles containing solid domain pairs coexisting in a fluid membrane, we adjusted vesicle inflation to manipulate membrane curvature and mapped the interdomain separation. A two-dimensional model of the pair potential predicts the salient experimental observations and reveals both attractions and repulsions, producing a potential minimum entirely a result of the solid domain rigidity and bending energy in the fluid membrane. The impact of vesicle inflation on domain separation in vesicles containing two solid domains was qualitatively consistent with observations in vesicles containing many domains. The behavior differs qualitatively from the pure repulsions between fluid membrane domains or interactions between nanoscopic inclusions whose repulsive or attractive character is not switchable.
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Affiliation(s)
- Weiyue Xin
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Hao Wu
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Gregory M Grason
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA
| | - Maria M Santore
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA.
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4
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Raman spectroscopy and DSC assay of the phase coexistence in binary DMPC/cholesterol multilamellar vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183514. [PMID: 33232709 DOI: 10.1016/j.bbamem.2020.183514] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 01/06/2023]
Abstract
The phospholipid/cholesterol binary model systems are an example of simple models whose structure has caused controversy and genuine interest over many decades. The cornerstone underlying the description of such models is the answer to the question of whether these membranes are separated into coexisting phases or domains. Here, we apply label-free Raman spectroscopy and differential scanning calorimetry (DSC) to verify the phase coexistence in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/cholesterol binary model. Raman spectra demonstrate the peculiarity at 30% molar fraction of cholesterol. Above this concentration, Raman data demonstrate similar characteristics at T = 291, 298, 303 K. At lower molar fractions, at 303 K, we found the agreement of Raman spectra with the predictions of the lever rule of cholesterol. Taken together, low cooperativity of the transition at 30 mol% and the fulfillment of the lever rule suggest the existence of nanoclusters composed of approximately 4 DMPC and 2 cholesterol molecules. At 298 K, the compliance of the lever rule was found in the range from 0 to 20 mol% of cholesterol. At 291 K, the addition of 5% cholesterol leads to the abrupt change of Raman spectra parameters and their continuous evolution with the further increase of cholesterol molar fraction. It seems that cholesterol plays a twofold role in binary mixtures; it reduces the intermolecular cooperativity and forms clusters whose size and DMPC-to-cholesterol ratio depend on cholesterol concentration and temperature.
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5
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Omar YAD, Sahu A, Sauer RA, Mandadapu KK. Nonaxisymmetric Shapes of Biological Membranes from Locally Induced Curvature. Biophys J 2020; 119:1065-1077. [PMID: 32860742 DOI: 10.1016/j.bpj.2020.07.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 07/07/2020] [Accepted: 07/15/2020] [Indexed: 01/24/2023] Open
Abstract
In various biological processes such as endocytosis and caveolae formation, the cell membrane is locally deformed into curved morphologies. Previous models to study membrane morphologies resulting from locally induced curvature often only consider the possibility of axisymmetric shapes-an indeed unphysical constraint. Past studies predict that the cell membrane buds at low resting tensions and stalls at a flat pit at high resting tensions. In this work, we lift the restriction to axisymmetry to study all possible membrane morphologies. Only if the resting tension of the membrane is low, we reproduce axisymmetric membrane morphologies. When the resting tension is moderate to high, we show that 1) axisymmetric membrane pits are unstable and 2) nonaxisymmetric ridge-shaped structures are energetically favorable. Furthermore, we find the interplay between intramembrane viscous flow and the rate of induced curvature affects the membrane's ability to transition into nonaxisymmetric ridges and axisymmetric buds. In particular, we show that axisymmetric buds are favored when the induced curvature is rapidly increased, whereas nonaxisymmetric ridges are favored when the curvature is slowly increased. Our results hold relevant implications for biological processes such as endocytosis and physical phenomena like phase separation in lipid bilayers.
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Affiliation(s)
- Yannick A D Omar
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California.
| | - Amaresh Sahu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California.
| | - Roger A Sauer
- Aachen Institute for Advanced Study in Computational Engineering Science, RWTH Aachen University, Aachen, Germany.
| | - Kranthi K Mandadapu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California.
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6
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Wongsirojkul N, Shimokawa N, Opaprakasit P, Takagi M, Hamada T. Osmotic-Tension-Induced Membrane Lateral Organization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:2937-2945. [PMID: 32175748 DOI: 10.1021/acs.langmuir.9b03893] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Alteration of lipid raft organization manifesting as phase separation is important for cellular processes, such as signaling and trafficking. Such behaviors and dynamics of lipid membranes can be affected by external stimuli including both physical and chemical stimuli. In this study, we focused on osmotic-tension-induced phase separation. The effects of osmotic tension on the phase behaviors of vesicles consisting of dioleoylphosphocholine (DOPC)/dipalmitoylphosphocholine (DPPC)/cholesterol (Chol) were quantitatively studied at different temperatures by fluorescence microscopy. We determined the ternary phase diagrams and found that tension leads to a shift in the miscibility temperature. Cholesterol plays a key role in determining the extent of this shift. In addition, we found that osmotic tension can enhance the line tension. The physicochemical mechanism of osmotic-pressure-induced phase separation is discussed.
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Affiliation(s)
- Nichaporn Wongsirojkul
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292, Japan
- School of Biochemical Engineering and Technology, Sirindhorn International Institute of Technology (SIIT), Thammasat University, Khlong Luang, Pathum Thani 12121, Thailand
| | - Naofumi Shimokawa
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292, Japan
| | - Pakorn Opaprakasit
- School of Biochemical Engineering and Technology, Sirindhorn International Institute of Technology (SIIT), Thammasat University, Khlong Luang, Pathum Thani 12121, Thailand
| | - Masahiro Takagi
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292, Japan
| | - Tsutomu Hamada
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292, Japan
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7
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Gu RX, Baoukina S, Tieleman DP. Phase Separation in Atomistic Simulations of Model Membranes. J Am Chem Soc 2020; 142:2844-2856. [DOI: 10.1021/jacs.9b11057] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Ruo-Xu Gu
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - Svetlana Baoukina
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - D. Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
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8
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Jiang Y, Pryse KM, Singamaneni S, Genin GM, Elson EL. Atomic force microscopy of phase separation on ruptured, giant unilamellar vesicles, and a mechanical pathway for the co-existence of lipid gel phases. J Biomech Eng 2019; 141:2735310. [PMID: 31141589 PMCID: PMC6611346 DOI: 10.1115/1.4043871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 05/26/2019] [Indexed: 11/08/2022]
Abstract
Giant unilamellar vesicles (GUVs) and supported lipid bilayers (SLBs) are synthetic model systems widely used in biophysical studies of lipid membranes. Although SLBs are advantageous for biophysical analysis, phase separation behaviors of lipid species in these two model systems can differ due to the lipid-substrate interactions that are present only for SLBs. In the present study, we report that in binary systems, certain phase domains on GUVs retain their original shapes and patterns after the GUVs rupture on glass surfaces. This enabled atomic force microscopy (AFM) experiments on phase domains, a procedure difficult to perform and interpret when applied to GUVs. Unusual phase behavior was evident in binary GUVs containing DLPC and either DPPC or DSPC. These DLPC/DSPC and DLPC/DPPC GUVs both presented the thermodynamic anomaly of having two co-existing gel phases. One phase (a bright phase) included a relatively high concentration of DiI-C20 but excluded Bodipy-HPC, and the other (dark phase) excluded both probes. The bright phases are of interest because they seem to stabilize dark phases against coalescence. Results suggested that the gel phases labeled by DiIC20 in the DLPC/DSPC membrane, which surround the dark gel phase, is an extra layer of membrane, indicating a highly curved structure that might stabilize the interior dark domains, thereby enabling the co-existence of two different gel phases. Results show the utility of AFM on collapsed GUVs, and suggest a possible mechanism for stabilization of lipid domains.
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Affiliation(s)
- Yanfei Jiang
- Department of Biochemistry and
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
| | - Kenneth M. Pryse
- Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63110
| | - Srikanth Singamaneni
- Department of Mechanical Engineering
and Materials Science,
Washington University,
St. Louis, MO 63110
| | - Guy M. Genin
- Department of Mechanical Engineeringand Materials Science,
Washington University,
St. Louis, MO 63110
- NSF Science and Technology,Center for Engineering Mechanobiology,
Washington University,
St. Louis, MO 63110
e-mail:
| | - Elliot L. Elson
- Department of Biochemistry and
Molecular Biophysics,
School of Medicine,
Washington University,
St. Louis, MO 63110
e-mail:
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9
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Balleza D, Mescola A, Marín-Medina N, Ragazzini G, Pieruccini M, Facci P, Alessandrini A. Complex Phase Behavior of GUVs Containing Different Sphingomyelins. Biophys J 2019; 116:503-517. [PMID: 30665697 DOI: 10.1016/j.bpj.2018.12.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 11/28/2018] [Accepted: 12/20/2018] [Indexed: 01/06/2023] Open
Abstract
Understanding the lateral organization of biological membranes plays a key role on the road to fully appreciate the physiological functions of this fundamental barrier between the inside and outside regions of a cell. Ternary lipid bilayers composed of a high and a low melting temperature lipid and cholesterol represent a model system that mimics some of the important thermodynamical features of much more complex lipid mixtures such as those found in mammal membranes. The phase diagram of these ternary mixtures can be studied exploiting fluorescence microscopy in giant unilamellar vesicles, and it is typically expected to give rise, for specific combinations of composition and temperature, to regions of two-phase coexistence and a region with three-phase coexistence, namely, the liquid-ordered, liquid-disordered, and solid phases. Whereas the observation of two-phase coexistence is routinely possible using fluorescence microscopy, the three-phase region is more elusive to study. In this article, we show that particular lipid mixtures containing diphytanoyl-phosphatidylcholine and cholesterol plus different types of sphingomyelin (SM) are prone to produce bilayer regions with more than two levels of fluorescence intensity. We found that these intensity levels occur at low temperature and are linked to the copresence of long and asymmetric chains in SMs and diphytanoyl-phosphatidylcholine in the lipid mixtures. We discuss the possible interpretations for this observation in terms of bilayer phase organization in the presence of sphingolipids. Additionally, we also show that in some cases, liposomes in the three-phase coexistence state exhibit extreme sensitivity to lateral tension. We hypothesize that the appearance of the different phases is related to the asymmetric structure of SMs and to interdigitation effects.
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Affiliation(s)
| | | | | | - Gregorio Ragazzini
- Istituto Nanoscienze CNR, S3, Modena, Italy; Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Università di Modena e Reggio Emilia, Modena, Italy
| | | | | | - Andrea Alessandrini
- Istituto Nanoscienze CNR, S3, Modena, Italy; Dipartimento di Scienze Fisiche, Matematiche e Informatiche, Università di Modena e Reggio Emilia, Modena, Italy.
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10
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Knorr RL, Steinkühler J, Dimova R. Micron-sized domains in quasi single-component giant vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1957-1964. [DOI: 10.1016/j.bbamem.2018.06.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 06/25/2018] [Accepted: 06/26/2018] [Indexed: 12/29/2022]
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11
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Pick H, Alves AC, Vogel H. Single-Vesicle Assays Using Liposomes and Cell-Derived Vesicles: From Modeling Complex Membrane Processes to Synthetic Biology and Biomedical Applications. Chem Rev 2018; 118:8598-8654. [PMID: 30153012 DOI: 10.1021/acs.chemrev.7b00777] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The plasma membrane is of central importance for defining the closed volume of cells in contradistinction to the extracellular environment. The plasma membrane not only serves as a boundary, but it also mediates the exchange of physical and chemical information between the cell and its environment in order to maintain intra- and intercellular functions. Artificial lipid- and cell-derived membrane vesicles have been used as closed-volume containers, representing the simplest cell model systems to study transmembrane processes and intracellular biochemistry. Classical examples are studies of membrane translocation processes in plasma membrane vesicles and proteoliposomes mediated by transport proteins and ion channels. Liposomes and native membrane vesicles are widely used as model membranes for investigating the binding and bilayer insertion of proteins, the structure and function of membrane proteins, the intramembrane composition and distribution of lipids and proteins, and the intermembrane interactions during exo- and endocytosis. In addition, natural cell-released microvesicles have gained importance for early detection of diseases and for their use as nanoreactors and minimal protocells. Yet, in most studies, ensembles of vesicles have been employed. More recently, new micro- and nanotechnological tools as well as novel developments in both optical and electron microscopy have allowed the isolation and investigation of individual (sub)micrometer-sized vesicles. Such single-vesicle experiments have revealed large heterogeneities in the structure and function of membrane components of single vesicles, which were hidden in ensemble studies. These results have opened enormous possibilities for bioanalysis and biotechnological applications involving unprecedented miniaturization at the nanometer and attoliter range. This review will cover important developments toward single-vesicle analysis and the central discoveries made in this exciting field of research.
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Affiliation(s)
- Horst Pick
- Institute of Chemical Sciences and Engineering , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Ana Catarina Alves
- Institute of Chemical Sciences and Engineering , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
| | - Horst Vogel
- Institute of Chemical Sciences and Engineering , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland
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12
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Knippenberg S, Fabre G, Osella S, Di Meo F, Paloncýová M, Ameloot M, Trouillas P. Atomistic Picture of Fluorescent Probes with Hydrocarbon Tails in Lipid Bilayer Membranes: An Investigation of Selective Affinities and Fluorescent Anisotropies in Different Environmental Phases. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9072-9084. [PMID: 29983063 DOI: 10.1021/acs.langmuir.8b01164] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
By reverting to spectroscopy, changes in the biological environment of a fluorescent probe can be monitored and the presence of various phases of the surrounding lipid bilayer membranes can be detected. However, it is currently not always clear in which phase the probe resides. The well-known orange 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbo-cyanine perchlorate (DiI-C18(5)) fluorophore, for instance, and the new, blue BODIPY (4,4-difluoro-4-bora-3 a,4 a-diaza- s-indacene) derivative were experimentally seen to target and highlight identical parts of giant unilamellar vesicles of various compositions, comprising mixtures of dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylcholine (DOPC), sphingomyelin (SM), and cholesterol (Chol). However, it was not clear which of the coexisting membrane phases were visualized (Bacalum et al., Langmuir. 2016, 32, 3495). The present study addresses this issue by utilizing large-scale molecular dynamics simulations and the z-constraint method, which allows evaluating Gibbs free-energy profiles. The current calculations give an indication why, at room temperature, both BODIPY and DiI-C18(5) probes prefer the gel (So) phase in DOPC/DPPC (2:3 molar ratio) and the liquid-ordered (Lo) phase in DOPC/SM/Chol (1:2:1 molar ratio) mixtures. This study highlights the important differences in orientation and location and therefore in efficiency between the probes when they are used in fluorescence microscopy to screen various lipid bilayer membrane phases. Dependent on the lipid composition, the angle between the transition-state dipole moments of both probes and the normal to the membrane is found to deviate clearly from 90°. It is seen that the DiI-C18(5) probe is located in the headgroup region of the SM/Chol mixture, in close contact with water molecules. A fluorescence anisotropy study also indicates that DiI-C18(5) gives rise to a distinctive behavior in the SM/Chol membrane compared to the other considered membranes. The latter behavior has not been seen for the studied BODIPY probe, which is located deeper in the membrane.
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Affiliation(s)
- S Knippenberg
- Department of Theoretical Chemistry and Biology , KTH Royal Institute of Technology , Roslagstullsbacken 15 , S-106 91 Stockholm , Sweden
- Biomedical Research Institute , Hasselt University , Agoralaan Building C , 3590 Diepenbeek , Belgium
| | - G Fabre
- LCSN-EA1069, Faculty of Pharmacy , Limoges University , 2 rue du Dr. Marcland , 87025 Limoges Cedex , France
| | - S Osella
- Centre of New Technologies , University of Warsaw , Banacha 2C , 02-097 Warsaw , Poland
| | - F Di Meo
- Faculty of Pharmacy , INSERM UMR 1248, Limoges University , 2 rue du Docteur Marcland , 87025 Limoges Cedex , France
| | - M Paloncýová
- Department of Theoretical Chemistry and Biology , KTH Royal Institute of Technology , Roslagstullsbacken 15 , S-106 91 Stockholm , Sweden
| | - M Ameloot
- Biomedical Research Institute , Hasselt University , Agoralaan Building C , 3590 Diepenbeek , Belgium
| | - P Trouillas
- Faculty of Pharmacy , INSERM UMR 1248, Limoges University , 2 rue du Docteur Marcland , 87025 Limoges Cedex , France
- Centre of Advanced Technologies and Materials, Faculty of Science , Palacký University , tř. 17 listopadu 12 , 771 46 Olomouc , Czech Republic
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13
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Werner S, Ebenhan J, Poppe M, Poppe S, Ebert H, Tschierske C, Bacia K. Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behavior. Part 2: Domain Formation by Self-Assembly in Lipid Bilayer Membranes. Polymers (Basel) 2017; 9:E476. [PMID: 30965779 PMCID: PMC6418688 DOI: 10.3390/polym9100476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 09/20/2017] [Accepted: 09/22/2017] [Indexed: 01/01/2023] Open
Abstract
Supramolecular self-assembly of membrane constituents within a phospholipid bilayer creates complex functional platforms in biological cells that operate in intracellular signaling, trafficking and membrane remodeling. Synthetic polyphilic compounds of macromolecular or small size can be incorporated into artificial phospholipid bilayers. Featuring three or four moieties of different philicities, they reach beyond ordinary amphiphilicity and open up avenues to new functions and interaction concepts. Here, we have incorporated a series of X-shaped bolapolyphiles into DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) bilayers of giant unilamellar vesicles. The bolapolyphiles consist of a rod-like oligo(phenylene ethynylene) (OPE) core, hydrophilic glycerol-based headgroups with or without oligo(ethylene oxide) expansions at both ends and two lateral alkyl chains attached near the center of the OPE core. In the absence of DPPC and water, the compounds showed thermotropic liquid-crystalline behavior with a transition between polyphilic and amphiphilic assembly (see part 1 in this issue). In DPPC membranes, various trends in the domain morphologies were observed upon structure variations, which entailed branched alkyl chains of various sizes, alkyl chain semiperfluorination and size expansion of the headgroups. Observed effects on domain morphology are interpreted in the context of the bulk behavior (part 1) and of a model that was previously developed based on spectroscopic and physicochemical data.
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Affiliation(s)
- Stefan Werner
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle, Germany.
| | - Jan Ebenhan
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle, Germany.
| | - Marco Poppe
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120 Halle, Germany.
| | - Silvio Poppe
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120 Halle, Germany.
| | - Helgard Ebert
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120 Halle, Germany.
| | - Carsten Tschierske
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120 Halle, Germany.
| | - Kirsten Bacia
- Department of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle, Germany.
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14
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Fernandez-Trillo F, Grover LM, Stephenson-Brown A, Harrison P, Mendes PM. Vesicles in Nature and the Laboratory: Elucidation of Their Biological Properties and Synthesis of Increasingly Complex Synthetic Vesicles. Angew Chem Int Ed Engl 2017; 56:3142-3160. [DOI: 10.1002/anie.201607825] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 10/12/2016] [Indexed: 12/19/2022]
Affiliation(s)
| | - Liam M. Grover
- School of Chemical Engineering; University of Birmingham; Edgbaston Birmingham B15 2TT UK
| | - Alex Stephenson-Brown
- School of Chemical Engineering; University of Birmingham; Edgbaston Birmingham B15 2TT UK
| | - Paul Harrison
- Institute of Inflammation and Ageing (IIA); University of Birmingham; Edgbaston Birmingham B15 2TT UK
| | - Paula M. Mendes
- School of Chemical Engineering; University of Birmingham; Edgbaston Birmingham B15 2TT UK
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15
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Fernandez-Trillo F, Grover LM, Stephenson-Brown A, Harrison P, Mendes PM. Vesikel in der Natur und im Labor: die Aufklärung der biologischen Eigenschaften und die Synthese zunehmend komplexer synthetischer Vesikel. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201607825] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
| | - Liam M. Grover
- School of Chemical Engineering; University of Birmingham; Edgbaston Birmingham B15 2TT Großbritannien
| | - Alex Stephenson-Brown
- School of Chemical Engineering; University of Birmingham; Edgbaston Birmingham B15 2TT Großbritannien
| | - Paul Harrison
- Institute of Inflammation and Ageing (IIA); University of Birmingham; Edgbaston Birmingham B15 2TT Großbritannien
| | - Paula M. Mendes
- School of Chemical Engineering; University of Birmingham; Edgbaston Birmingham B15 2TT Großbritannien
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16
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Bacalum M, Wang L, Boodts S, Yuan P, Leen V, Smisdom N, Fron E, Knippenberg S, Fabre G, Trouillas P, Beljonne D, Dehaen W, Boens N, Ameloot M. A Blue-Light-Emitting BODIPY Probe for Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:3495-3505. [PMID: 27003513 DOI: 10.1021/acs.langmuir.6b00478] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Here we describe a new BODIPY-based membrane probe (1) that provides an alternative to dialkylcarbocyanine dyes, such as DiI-C18, that can be excited in the blue spectral region. Compound 1 has unbranched octadecyl chains at the 3,5-positions and a meso-amino function. In organic solvents, the absorption and emission maxima of 1 are determined mainly by solvent acidity and dipolarity. The fluorescence quantum yield is high and reaches 0.93 in 2-propanol. The fluorescence decays are well fitted with a single-exponential in pure solvents and in small and giant unilamellar vesicles (GUV) with a lifetime of ca. 4 ns. Probe 1 partitions in the same lipid phase as DiI-C18(5) for lipid mixtures containing sphingomyelin and for binary mixtures of dipalmitoylphosphatidylcholine (DPPC) and dioleoylphosphatidylcholine (DOPC). The lipid phase has no effect on the fluorescence lifetime but influences the fluorescence anisotropy. The translational diffusion coefficients of 1 in GUVs and OLN-93 cells are of the same order as those reported for DiI-C18. The directions of the absorption and emission transition dipole moments of 1 are calculated to be parallel. This is reflected in the high steady-state fluorescence anisotropy of 1 in high ordered lipid phases. Molecular dynamic simulations of 1 in a model of the DOPC bilayer indicate that the average angle of the transition moments with respect to membrane normal is ca. 70°, which is comparable with the value reported for DiI-C18.
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Affiliation(s)
- Mihaela Bacalum
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
- Department of Life and Environmental Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering , Reactorului 30, Măgurele, 077125, Romania
| | - Lina Wang
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Stijn Boodts
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Peijia Yuan
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Volker Leen
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Nick Smisdom
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
| | - Eduard Fron
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Stefan Knippenberg
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
- Division of Theoretical Chemistry and Biology, KTH Royal Institute of Technology, School of Biotechnology , Roslagstullsbacken 15, S-106 91 Stockholm, Sweden
| | - Gabin Fabre
- LCSN-EA1069, Faculté de Pharmacie, Université de Limoges , 2, rue du Dr. Marcland, 87025 Limoges Cedex, France
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University , tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Patrick Trouillas
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University , tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
- INSERM UMR-S850, Faculté de Pharmacie, Université de Limoges , 2 rue du Docteur Marcland, 87025 Limoges Cedex, France
- Service de Chimie des Matériaux Nouveaux, Université de Mons , Place du Parc 20, B-7000 Mons, Belgium
| | - David Beljonne
- Service de Chimie des Matériaux Nouveaux, Université de Mons , Place du Parc 20, B-7000 Mons, Belgium
| | - Wim Dehaen
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Noël Boens
- Department of Chemistry, Katholieke Universiteit Leuven (KU Leuven) , Celestijnenlaan 200f - bus 02404, 3001 Leuven, Belgium
| | - Marcel Ameloot
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590, Diepenbeek, Belgium
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17
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Malacrida L, Gratton E, Jameson DM. Model-free methods to study membrane environmental probes: a comparison of the spectral phasor and generalized polarization approaches. Methods Appl Fluoresc 2015; 3:047001. [PMID: 27182438 PMCID: PMC4862737 DOI: 10.1088/2050-6120/3/4/047001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this note, we present a discussion of the advantages and scope of model-free analysis methods applied to the popular solvatochromic probe LAURDAN, which is widely used as an environmental probe to study dynamics and structure in membranes. In particular, we compare and contrast the generalized polarization approach with the spectral phasor approach. To illustrate our points we utilize several model membrane systems containing pure lipid phases and, in some cases, cholesterol or surfactants. We demonstrate that the spectral phasor method offers definitive advantages in the case of complex systems.
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Affiliation(s)
- Leonel Malacrida
- Área de Investigación Respiratoria, Departamento de Fisiopatología, Hospital de Medicina-Facultad de Medicina, Universidad de la República, Montevideo, Uruguay; Biochemistry and Proteomic Analytical Unit, Institut Pasteur of Montevideo, Montevideo, Uruguay
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Biomedical Engineering Department, University of California at Irvine, Irvine, CA 92697, USA
| | - David M Jameson
- Department of Cell and Molecular Biology, University of Hawaii at Manoa, 651 Halo St., BSB222, Honolulu, HI 96813, USA
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18
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Jeppesen JC, Solovyeva V, Brewer JR, Johannes L, Hansen PL, Simonsen AC. Slow Relaxation of Shape and Orientational Texture in Membrane Gel Domains. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12699-12707. [PMID: 26501924 DOI: 10.1021/acs.langmuir.5b03168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Gel domains in lipid bilayers are structurally more complex than fluid domains. Growth dynamics can lead to noncircular domains with a heterogeneous orientational texture. Most model membrane studies involving gel domain morphology and lateral organization assume the domains to be static. Here we show that rosette shaped gel domains, with heterogeneous orientational texture and a central topological defect, after early stage growth, undergo slow relaxation. On a time scale of days to weeks domains converge to circular shapes and approach uniform texture. 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) enriched gel domains are grown by cooling 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC):DPPC bilayers into the solid-liquid phase coexistence region and are visualized with fluorescence microscopy. The relaxation of individual domains is quantified through image analysis of time-lapse image series. We find a shape relaxation mechanism which is inconsistent with Ostwald ripening and coalescence as observed in membrane systems with coexisting liquid phases. Moreover, domain texture changes in parallel with the changes in domain shape, and selective melting and growth of particular subdomains cause the texture to become more uniform. We propose a relaxation mechanism based on relocation of lipids from high-energy lattice positions, through evaporation-condensation and edge diffusion, to low-energy positions. The relaxation process is modified significantly by binding Shiga toxin, a bacterial toxin from Shigella dysenteriae, to the membrane surface. Binding alters the equilibrium shape of the gel domains from circular to eroded rosettes with disjointed subdomains. This observation may be explained by edge diffusion while evaporation-condensation is restricted, and it provides further support for the proposed overall relaxation mechanism.
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Affiliation(s)
| | | | | | - Ludger Johannes
- Institut Curie, UMR3666 CNRS, U1143 INSERM, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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Schulz M, Binder WH. Mixed Hybrid Lipid/Polymer Vesicles as a Novel Membrane Platform. Macromol Rapid Commun 2015; 36:2031-41. [DOI: 10.1002/marc.201500344] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 09/01/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Matthias Schulz
- Martin-Luther University Halle-Wittenberg; Chair of Macromolecular Chemistry; Faculty of Natural Sciences II (Chemistry, Physics and Mathematics); Institute of Chemistry; D-06120 Halle (Saale) Germany
| | - Wolfgang H. Binder
- Martin-Luther University Halle-Wittenberg; Chair of Macromolecular Chemistry; Faculty of Natural Sciences II (Chemistry, Physics and Mathematics); Institute of Chemistry; D-06120 Halle (Saale) Germany
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20
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Winterhalder MJ, Zumbusch A. Beyond the borders--Biomedical applications of non-linear Raman microscopy. Adv Drug Deliv Rev 2015; 89:135-44. [PMID: 25959426 DOI: 10.1016/j.addr.2015.04.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/17/2015] [Accepted: 04/29/2015] [Indexed: 11/26/2022]
Abstract
Raman spectroscopy offers great promise for label free imaging in biomedical applications. Its use, however, is hampered by the long integration times required and the presence of autofluorescence in many samples which outshines the Raman signals. In order to overcome these limitations, a variety of different non-linear Raman imaging techniques have been developed over the last decade. This review describes biomedical applications of these novel but already mature imaging techniques.
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21
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Jung J, Mori T, Kobayashi C, Matsunaga Y, Yoda T, Feig M, Sugita Y. GENESIS: a hybrid-parallel and multi-scale molecular dynamics simulator with enhanced sampling algorithms for biomolecular and cellular simulations. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2015; 5:310-323. [PMID: 26753008 PMCID: PMC4696414 DOI: 10.1002/wcms.1220] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 03/12/2015] [Accepted: 03/23/2015] [Indexed: 12/18/2022]
Abstract
GENESIS (Generalized-Ensemble Simulation System) is a new software package for molecular dynamics (MD) simulations of macromolecules. It has two MD simulators, called ATDYN and SPDYN. ATDYN is parallelized based on an atomic decomposition algorithm for the simulations of all-atom force-field models as well as coarse-grained Go-like models. SPDYN is highly parallelized based on a domain decomposition scheme, allowing large-scale MD simulations on supercomputers. Hybrid schemes combining OpenMP and MPI are used in both simulators to target modern multicore computer architectures. Key advantages of GENESIS are (1) the highly parallel performance of SPDYN for very large biological systems consisting of more than one million atoms and (2) the availability of various REMD algorithms (T-REMD, REUS, multi-dimensional REMD for both all-atom and Go-like models under the NVT, NPT, NPAT, and NPγT ensembles). The former is achieved by a combination of the midpoint cell method and the efficient three-dimensional Fast Fourier Transform algorithm, where the domain decomposition space is shared in real-space and reciprocal-space calculations. Other features in SPDYN, such as avoiding concurrent memory access, reducing communication times, and usage of parallel input/output files, also contribute to the performance. We show the REMD simulation results of a mixed (POPC/DMPC) lipid bilayer as a real application using GENESIS. GENESIS is released as free software under the GPLv2 licence and can be easily modified for the development of new algorithms and molecular models. WIREs Comput Mol Sci 2015, 5:310–323. doi: 10.1002/wcms.1220
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Affiliation(s)
- Jaewoon Jung
- Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science Kobe, Japan
| | - Takaharu Mori
- Theoretical Molecular Science Laboratory, RIKEN Wako-shi, Japan
| | - Chigusa Kobayashi
- Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science Kobe, Japan
| | - Yasuhiro Matsunaga
- Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science Kobe, Japan
| | - Takao Yoda
- Nagahama Institute of Bio-Science and Technology Nagahama, Japan
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, and Department of Chemistry, Michigan State University East Lansing, MI, USA
| | - Yuji Sugita
- Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science Kobe, Japan; Theoretical Molecular Science Laboratory, RIKEN Wako-shi, Japan; Interdisciplinary Theoretical Science Research Group, RIKEN Wako-shi, Japan; Laboratory for Biomolecular Function Simulation, RIKEN Quantitative Biology Center Kobe, Japan
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22
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Chen D, Santore MM. Hybrid copolymer-phospholipid vesicles: phase separation resembling mixed phospholipid lamellae, but with mechanical stability and control. SOFT MATTER 2015; 11:2617-26. [PMID: 25687473 DOI: 10.1039/c4sm02502d] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Vesicles whose bilayer membranes contain phospholipids mixed with co-polymers or surfactants comprise new hybrid materials having potential applications in drug delivery, sensors, and biomaterials. Here we describe a model polymer-phospholipid hybrid membrane system exhibiting strong similarities to binary phospholipid mixtures, but with more robust membrane mechanics. A lamella-forming graft copolymer, PDMS-co-PEO (polydimethylsiloxane-co-polyethylene oxide) was blended with a high melting temperature phospholipid, DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine), over a broad compositional range. The resulting giant hybrid unilamellar vesicles were compared qualitatively and quantitatively to analogous mixed phospholipid membranes in which a low melting temperature phospholipid, DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine), was blended with DPPC. The mechanical properties of the hybrid vesicles, even when phase separated, were robust with high lysis stresses and strains approaching those of the pure copolymer vesicles. The temperature-composition phase diagram of the hybrid vesicles closely resembled that of the mixed phospholipids; with only slightly greater nonidealities in the hybrid compared with DOPC/DPPC mixed membranes. In both systems, it was demonstrated that tension could be used to manipulate DPPC solidification into domains of patchy or striped morphologies that exhibited different tracer incorporation. The patch and stripe-shaped domains are thought to be different solid DPPC polymorphys: ripple and tilt (or gel). This work demonstrates that in mixed-phospholipid bilayers where a high-melting phospholipid solidifies on cooling, the lower-melting phospholipid may be substituted by an appropriate copolymer to improve mechanical properties while retaining the underlying membrane physics.
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Affiliation(s)
- Dong Chen
- Department of Physics, University of Massachusetts at Amherst, 120 Governors Drive, Amherst, MA 01003, USA
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23
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Balleza D, Garcia-Arribas AB, Sot J, Ruiz-Mirazo K, Goñi FM. Ether- versus ester-linked phospholipid bilayers containing either linear or branched apolar chains. Biophys J 2015; 107:1364-74. [PMID: 25229144 DOI: 10.1016/j.bpj.2014.07.036] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 07/03/2014] [Accepted: 07/15/2014] [Indexed: 10/24/2022] Open
Abstract
We studied the properties of bilayers formed by ether-and ester-containing phospholipids, whose hydrocarbon chains can be either linear or branched, using sn-1,2 dipalmitoyl, dihexadecyl, diphytanoyl, and diphytanyl phosphatidylcholines (DPPC, DHPC, DPhoPC, and DPhPC, respectively) either pure or in binary mixtures. Differential scanning calorimetry and confocal fluorescence microscopy of giant unilamellar vesicles concurred in showing that equimolar mixtures of linear and branched lipids gave rise to gel/fluid phase coexistence at room temperature. Mixtures containing DHPC evolved in time (0.5 h) from initial reticulated domains to extended solid ones when an equilibrium was achieved. The nanomechanical properties of supported planar bilayers formed by each of the four lipids studied by atomic force microscopy revealed average breakdown forces Fb decreasing in the order DHPC ≥ DPPC > DPhoPC >> DPhPC. Moreover, except for DPPC, two different Fb values were found for each lipid. Atomic force microscopy imaging of DHPC was peculiar in showing two coexisting phases of different heights, probably corresponding to an interdigitated gel phase that gradually transformed, over a period of 0.5 h, into a regular tilted gel phase. Permeability to nonelectrolytes showed that linear-chain phospholipids allowed a higher rate of solute + water diffusion than branched-chain phospholipids, yet the former supported a smaller extent of swelling of the corresponding vesicles. Ether or ester bonds appeared to have only a minor effect on permeability.
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Affiliation(s)
- Daniel Balleza
- Unidad de Biofísica CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Aritz B Garcia-Arribas
- Unidad de Biofísica CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Jesús Sot
- Unidad de Biofísica CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain
| | - Kepa Ruiz-Mirazo
- Unidad de Biofísica CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain; Departamento de Lógica y Filosofía de la Ciencia, UPV/EHU, Donostia-San Sebastián, Spain
| | - Félix M Goñi
- Unidad de Biofísica CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, Spain.
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24
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Three dimensional (temperature–tension–composition) phase map of mixed DOPC–DPPC vesicles: Two solid phases and a fluid phase coexist on three intersecting planes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2788-97. [DOI: 10.1016/j.bbamem.2014.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/23/2014] [Accepted: 07/16/2014] [Indexed: 02/02/2023]
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25
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Chen D, Santore MM. 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-rich domain formation in binary phospholipid vesicle membranes: two-dimensional nucleation and growth. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9484-9493. [PMID: 25084141 DOI: 10.1021/la502089t] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Decades of study have probed phase transitions in model phospholipid bilayers and vesicles, especially in the context of the equilibrium phase diagram. Critical to the response of vesicles to environmental triggers, to the ultimate domain morphology, and to the approach to equilibrium (or not), we present here a study of domain formation in vesicles, focusing on a mechanism by which the cooling rate, tension, and composition affect the first appearance (nucleation) and subsequent growth of solid membrane domains. Employing a popular mixed membrane model based on DOPC and DPPC (1,2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, respectively), we examined phase separation in giant two-component vesicles that were cooled from the one-phase fluid (Lα) region of the phase diagram into a region of fluid (Lα)-solid coexistence. At moderate and low membrane tensions, cooling produced solid DPPC-rich domains appearing as compact patches or irregular hexagons and likely with a Pβ' (ripple) arrangement. (The compact solid domains in this study differed distinctly from striped domains in vesicles of the same composition, in terms of molecular organization and conditions of first appearance during cooling.) The amounts of these solid domains were shown to adhere to the lever arm rule for a tie line on the phase diagram, with a solid composition near 95 mol % DPPC. The nucleation of the compact solid domains occurred in a short period, followed by rapid addition of ordered molecules to the nucleated domains, excluding tracer dye. The two-dimensional nucleation density of these compact solid domains (in the range of 10(-2)-10(-1) μm(-2)) was found to increase with the cooling rate (equivalent to the quench depth) with a greater than linear dependence. The 2-D nucleation density was also seen to decrease with membrane tension, presumably because membrane tension increases the line tension around a domain that opposes nucleation. A sigmoidal dependence of the nucleation density on the DPPC concentration was also found. With cooling rates in excess of ∼1 °C/min, solid domains persisted down to room temperature, likely passing from a preferred equilibrium to a local equilibrium with continued cooling. As a result of the persistence of the originally nucleated domains and the conservation of DPPC in the membrane, we observed an increasingly greater number of smaller domains with increased cooling rates. The domains in these vesicles were compact or hexagonal-shaped in contrast to flower-shaped dendritic domains in the same membrane system in a supported membrane configuration.
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Affiliation(s)
- Dong Chen
- Department of Physics and ‡Department of Polymer Science and Engineering, University of Massachusetts , Amherst, Massachusetts 01003, United States
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26
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Pinto SN, Fernandes F, Fedorov A, Futerman AH, Silva LC, Prieto M. A combined fluorescence spectroscopy, confocal and 2-photon microscopy approach to re-evaluate the properties of sphingolipid domains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2099-110. [DOI: 10.1016/j.bbamem.2013.05.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 05/10/2013] [Accepted: 05/13/2013] [Indexed: 12/29/2022]
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27
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Pan J, Heberle FA, Petruzielo RS, Katsaras J. Using small-angle neutron scattering to detect nanoscopic lipid domains. Chem Phys Lipids 2013; 170-171:19-32. [PMID: 23518250 DOI: 10.1016/j.chemphyslip.2013.02.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 02/27/2013] [Accepted: 02/28/2013] [Indexed: 11/25/2022]
Abstract
The cell plasma membrane is a complex system, which is thought to be capable of exhibiting non-random lateral organization. Studies of live cells and model membranes have yielded mechanisms responsible for the formation, growth, and maintenance of nanoscopic heterogeneities, although the existence and mechanisms that give rise to these heterogeneities remain controversial. Small-angle neutron scattering (SANS) is a tool ideally suited to interrogate lateral heterogeneity in model membranes, primarily due to its unique spatial resolution (i.e., ~5-100nm) and its ability to resolve structure with minimal perturbation to the membrane. In this review we examine several methods used to analyze the SANS signal arising from freely suspended unilamellar vesicles containing lateral heterogeneity. Specifically, we discuss an analytical model for a single, round domain on a spherical vesicle. We then discuss a numerical method that uses Monte Carlo simulation to describe systems with multiple domains and/or more complicated morphologies. Also discussed are several model-independent approaches that are sensitive to membrane heterogeneity. The review concludes with several recent applications of SANS to the study of membrane raft mixtures.
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Affiliation(s)
- Jianjun Pan
- Biology and Soft Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States.
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28
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Kurniawan Y, Venkataramanan KP, Scholz C, Bothun GD. n-Butanol Partitioning and Phase Behavior in DPPC/DOPC Membranes. J Phys Chem B 2012; 116:5919-24. [DOI: 10.1021/jp301340k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yogi Kurniawan
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston,
Rhode Island 02881, United States
| | - Keerthi P. Venkataramanan
- Biotechnology Science and Engineering
program, University of Alabama in Huntsville, 301 Sparkman Dr., Huntsville, Alabama 35899, United States
| | - Carmen Scholz
- Department of Chemistry, University of Alabama in Huntsville, 301 Sparkman Dr.,
Huntsville, Alabama 35899, United States
| | - Geoffrey D. Bothun
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston,
Rhode Island 02881, United States
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29
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Cacas JL, Furt F, Le Guédard M, Schmitter JM, Buré C, Gerbeau-Pissot P, Moreau P, Bessoule JJ, Simon-Plas F, Mongrand S. Lipids of plant membrane rafts. Prog Lipid Res 2012; 51:272-99. [PMID: 22554527 DOI: 10.1016/j.plipres.2012.04.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lipids tend to organize in mono or bilayer phases in a hydrophilic environment. While they have long been thought to be incapable of coherent lateral segregation, it is now clear that spontaneous assembly of these compounds can confer microdomain organization beyond spontaneous fluidity. Membrane raft microdomains have the ability to influence spatiotemporal organization of protein complexes, thereby allowing regulation of cellular processes. In this review, we aim at summarizing briefly: (i) the history of raft discovery in animals and plants, (ii) the main findings about structural and signalling plant lipids involved in raft segregation, (iii) imaging of plant membrane domains, and their biochemical purification through detergent-insoluble membranes, as well as the existing debate on the topic. We also discuss the potential involvement of rafts in the regulation of plant physiological processes, and further discuss the prospects of future research into plant membrane rafts.
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Affiliation(s)
- Jean-Luc Cacas
- Laboratoire de Biogenèse Membranaire, UMR 5200 CNRS, Université de Bordeaux, 146 Rue Léo Saignat, 33076 Bordeaux, France
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Bandekar A, Sofou S. Floret-shaped solid domains on giant fluid lipid vesicles induced by pH. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:4113-4122. [PMID: 22276950 DOI: 10.1021/la204765r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lateral lipid phase separation of titratable PS or PA lipids and their assembly in domains induced by changes in pH are significant in liposome-based drug delivery: environmentally responsive lipid heterogeneities can be tuned to alter collective membrane properties such as permeability (altering drug release) and surface topography (altering drug carrier reactivity) impacting, therefore, the therapeutic outcomes. At the micrometer scale fluorescence microscopy on giant unilamellar fluid vesicles (GUVs) shows that lowering pH (from 7.0 to 5.0) promotes condensation of titratable PS or PA lipids into beautiful floret-shaped domains in which lipids are tightly packed via hydrogen-bonding and van der Waals interactions. The order of lipid packing within domains increases radially toward the domain center. Lowering pH enhances the lipid packing order, and at pH 5.0 domains appear to be entirely in the solid (gel) phase. Domains phenomenologically comprise a circular "core" cap beyond which interfacial instabilities emerge resembling leaf-like stripes. At pH 5.0 stripes are of almost vanishing Gaussian curvature independent of GUVs' preparation path and in agreement with a general condensation mechanism. Increasing incompressibility of domains is strongly correlated with a larger number of thinner stripes per domain and increasing relative rigidity of domains with smaller core cap areas. Line tension drives domain ripening; however, the final domain shape is a result of enhanced incompressibility and rigidity maximized by domain coupling across the bilayer. Introduction of a transmembrane osmotic gradient (hyperosmotic on the outer lipid leaflet) allows the domain condensation process to reach its maximum extent which, however, is limited by the minimal expansivity of the continuous fluid membrane.
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Affiliation(s)
- Amey Bandekar
- Biomedical Engineering and Chemical and Biochemical Engineering, Rutgers University, Piscataway, New Jersey 08854, United States
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Dodes Traian MM, Flecha FLG, Levi V. Imaging lipid lateral organization in membranes with C-laurdan in a confocal microscope. J Lipid Res 2012; 53:609-616. [PMID: 22184757 PMCID: PMC3276485 DOI: 10.1194/jlr.d021311] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 12/01/2011] [Indexed: 11/20/2022] Open
Abstract
Lateral organization of biological membranes is frequently studied using fluorescence microscopy. One of the most widely used probes for these studies is 2-dimethylamino-6-lauroylnaphthalene (laurdan). The fluorescence of this probe is sensitive to the environment polarity, and thus laurdan reports the local penetration of water when inserted in membranes. Unfortunately, this probe can only be used under two-photon excitation due to its low photostability. This is a very important limitation, because there are not too many laboratories with capability for two-photon microscopy. In this work, we explored the performance of 6-dodecanoyl-2-[N-methyl-N-(carboxymethyl)amino]naphthalene (C-laurdan), a carboxyl-modified version of laurdan, for imaging biological membranes using a conventional confocal microscopy setup. We acquired generalized polarization (GP) images of C-laurdan inserted in giant unillamelar vesicles composed of binary mixtures of lipids and verified that the probe allows observing the coexistence of different phases. We also tested the performance of the probe for measurement with living cells and registered GP images of melanophore cells labeled with C-laurdan in which we could observe highly ordered regions such as filopodia. These findings show that C-laurdan can be successfully employed for studies of membrane lateral organization using a conventional confocal microscope and can open the possibility of studying a wide variety of membrane-related processes.
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Affiliation(s)
- Martín M Dodes Traian
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, CP 1428 Ciudad de Buenos Aires, Argentina; Laboratorio de Biofísica Molecular, Instituto de Química y Fisicoquímica Biológicas, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - F Luis González Flecha
- Laboratorio de Biofísica Molecular, Instituto de Química y Fisicoquímica Biológicas, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - Valeria Levi
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, CP 1428 Ciudad de Buenos Aires, Argentina.
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Correlation between the ripple phase and stripe domains in membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2849-58. [DOI: 10.1016/j.bbamem.2011.08.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 08/12/2011] [Accepted: 08/16/2011] [Indexed: 12/19/2022]
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Juhasz J, Davis JH, Sharom FJ. Fluorescent probe partitioning in GUVs of binary phospholipid mixtures: implications for interpreting phase behavior. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:19-26. [PMID: 21945563 DOI: 10.1016/j.bbamem.2011.09.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/25/2011] [Accepted: 09/08/2011] [Indexed: 11/16/2022]
Abstract
The phase behavior of membrane lipids is known to influence the organization and function of many integral proteins. Giant unilamellar vesicles (GUVs) provide a very useful model system in which to examine the details of lipid phase separation using fluorescence imaging. The visualization of domains in GUVs of binary and ternary lipid mixtures requires fluorescent probes with partitioning preference for one of the phases present. To avoid possible pitfalls when interpreting the phase behavior of these lipid mixtures, sufficiently thorough characterization of the fluorescent probes used in these studies is needed. It is now evident that fluorescent probes display different partitioning preferences between lipid phases, depending on the specific lipid host system. Here, we demonstrate the benefit of using a panel of fluorescent probes and confocal fluorescence microscopy to examine phase separation in GUVs of binary mixtures of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Patch and fibril gel phase domains were found to co-exist with liquid disordered (l(d)) domains on the surface of GUVs composed of 40:60 mol% DOPC/DPPC, over a wide range of temperatures (14-25°C). The fluorescent lipid, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl (NBD-DPPE), proved to be the most effective probe for visualization of fibril domains. In the presence of Lissamine(TM) rhodamine B 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (Rh-DPPE) we were unable to detect fibril domains. This fluorophore also affected the partitioning behavior of other fluorescent probes. Overall, we show that the selection of different fluorescent probes as lipid phase reporters can result in very different interpretation of the phase behavior of DOPC/DPPC mixtures.
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Affiliation(s)
- Janos Juhasz
- Department of Physics, University of Guelph, Guelph, ON, Canada
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AFM characterization of spin-coated multilayered dry lipid films prepared from aqueous vesicle suspensions. Colloids Surf B Biointerfaces 2011; 82:25-32. [DOI: 10.1016/j.colsurfb.2010.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 07/26/2010] [Accepted: 08/04/2010] [Indexed: 11/20/2022]
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Vesicles with charged domains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1338-47. [DOI: 10.1016/j.bbamem.2009.12.023] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 12/15/2009] [Accepted: 12/22/2009] [Indexed: 01/29/2023]
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36
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Imaging cerebroside-rich domains for phase and shape characterization in binary and ternary mixtures. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1357-67. [DOI: 10.1016/j.bbamem.2009.11.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2009] [Revised: 11/19/2009] [Accepted: 11/20/2009] [Indexed: 12/18/2022]
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Yu Y, Vroman JA, Bae SC, Granick S. Vesicle budding induced by a pore-forming peptide. J Am Chem Soc 2010; 132:195-201. [PMID: 20000420 DOI: 10.1021/ja9059014] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe, in a system whose uniqueness is that the presence of pores allows the volume to vary as budding proceeds, how phase separation on the surface of spheres extrudes material in the process called "budding". The system is giant phospholipid vesicles (GUVs) containing phase-separated regions of DOPC (soft, liquid) and DPPC (stiff, gel), with cholesterol and without it. Budding is triggered by adding the cationic pore-forming peptide, melittin. Without cholesterol, fluorescence experiments show that melittin selectively binds to the liquid domains, inducing them to form mainly exocytotic monodisperse smaller vesicle buds of this same material, causing the parent GUV to shrink. The effect of cholesterol is to produce just a few large buds following domain coalescence, rather than numerous smaller monodisperse ones. Line tension is experimentally shown to be essential for budding in this multicomponent membrane.
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Affiliation(s)
- Yan Yu
- Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois 61801, USA
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Volkmer A. Coherent Raman Scattering Microscopy. EMERGING RAMAN APPLICATIONS AND TECHNIQUES IN BIOMEDICAL AND PHARMACEUTICAL FIELDS 2010. [DOI: 10.1007/978-3-642-02649-2_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Bernchou U, Ipsen JH, Simonsen AC. Growth of solid domains in model membranes: quantitative image analysis reveals a strong correlation between domain shape and spatial position. J Phys Chem B 2009; 113:7170-7. [PMID: 19296622 DOI: 10.1021/jp809989t] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The nucleation and growth of solid domains in supported bilayers composed of a binary mixture of equimolar 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) have been studied using combined fluorescence microscopy and AFM. We have found that the formation of the DPPC-enriched solid domains occurs by a combination of homogeneous and heterogeneous nucleation and that the nucleation density is directly proportional to the cooling rate. Furthermore, during cooling the shape of the domains evolve from compact to a branched morphology. This suggests that the growth is controlled by the diffusion of DPPC from the liquid phase toward the solid domain interface. In the late stages of the growth, we observe that the size and overall shape of the domains depend on the position of the nucleation points relative to the surrounding nucleation point positions. To analyze this effect, the nucleation points were used as generators in a Voronoi construction. Associated with each generator is a Voronoi polygon that contains all points closer to this generator than to any other. Through a detailed quantitative analysis of the Voronoi cells and the domains, we have found that their area, orientation, and asymmetry correlate and that the correlation becomes stronger for larger domains. This means that the spatial distribution of the nucleation points regulate the domain shape.
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Affiliation(s)
- Uffe Bernchou
- MEMPHYS Center for Biomembrane Physics, Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
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Mills TT, Huang J, Feigenson GW, Nagle JF. Effects of cholesterol and unsaturated DOPC lipid on chain packing of saturated gel-phase DPPC bilayers. Gen Physiol Biophys 2009; 28:126-139. [PMID: 19592709 PMCID: PMC2731993 DOI: 10.4149/gpb_2009_02_126] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Wide angle x-ray scattering (WAXS) from oriented lipid multilayers was used to study the effect of adding cholesterol (Chol) or 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) to gel-phase 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers. Small quantities (X < 0.10 mole fraction) of both molecules disrupt the tight packing of tilted chains of pure gel-phase DPPC, forming a more disordered, untilted phase. The addition of larger quantities of DOPC causes the sample to phase-separate into a gel-phase, characterized by a narrow WAXS peak, and liquid disordered phase, characterized by wide, diffuse WAXS scattering. In contrast, two WAXS peaks indicative of two coexisting phases were not observed in Chol/DPPC mixtures (X(Chol) = 0.07 to 0.40). Instead, Chol caused a gradual increase in the width of the WAXS peak, consistent with a gradual change from a more gel-like to a more liquid-like state rather than passing through a region of two phase coexistence. Our WAXS data include a huge amount of information. A new method of analysis suggests that WAXS data may provide definitive results relating to the disagreements between previously published phase diagrams for Chol/DPPC.
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Affiliation(s)
- Thalia T. Mills
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Juyang Huang
- Department of Physics, Texas Tech University, Lubbock, TX 79409
| | | | - John F. Nagle
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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41
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Wang HW, Fu Y, Huff TB, Le TT, Wang H, Cheng JX. Chasing lipids in health and diseases by coherent anti-Stokes Raman scattering microscopy. VIBRATIONAL SPECTROSCOPY 2009; 50:160-167. [PMID: 19763281 PMCID: PMC2744966 DOI: 10.1016/j.vibspec.2008.11.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The integration of near IR picosecond pulse excitation, collinear beam geometry, epi-detection, and laser-scanning has produced a coherent anti-Stokes Raman scattering (CARS) microscope with a detection sensitivity of 10(5) vibrational oscillators, sub-micron 3D resolution, and video-rate acquisition speed. The incorporation of spectral detection and other imaging modalities has added versatility to the CARS microscope. These advances allowed sensitive interrogation of biological samples, particularly lipids that have a high density of CH(2) groups. With initial applications to membrane domains, lipid bodies, demyelinating diseases, obesity, and cardiovascular diseases, CARS microscopy is poised to become a powerful bio-imaging tool with the availability of a multifunctional, affordable, easy-to-operate CARS microscope, and the development of CARS endoscopy for in vivo diagnosis.
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Affiliation(s)
- Han-Wei Wang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Yan Fu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Terry B. Huff
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Thuc T. Le
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Haifeng Wang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Ji-Xin Cheng
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
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42
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Oreopoulos J, Yip CM. Probing membrane order and topography in supported lipid bilayers by combined polarized total internal reflection fluorescence-atomic force microscopy. Biophys J 2009; 96:1970-84. [PMID: 19254557 DOI: 10.1016/j.bpj.2008.11.041] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 11/17/2008] [Indexed: 11/19/2022] Open
Abstract
Determining the local structure, dynamics, and conformational requirements for protein-protein and protein-lipid interactions in membranes is critical to understanding biological processes ranging from signaling to the translocating and membranolytic action of antimicrobial peptides. We report here the application of a combined polarized total internal reflection fluorescence microscopy-in situ atomic force microscopy platform. This platform's ability to image membrane orientational order was demonstrated on DOPC/DSPC/cholesterol model membranes containing the fluorescent membrane probe, DiI-C(20) or BODIPY-PC. Spatially resolved order parameters and fluorophore tilt angles extracted from the polarized total internal reflection fluorescence microscopy images were in good agreement with the topographical details resolved by in situ atomic force microscopy, portending use of this technique for high-resolution characterization of membrane domain structures and peptide-membrane interactions.
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Affiliation(s)
- John Oreopoulos
- Institute of Biomaterials and Biomedical Engineering, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
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43
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Viveros-Méndez PX, Méndez-Alcaraz JM, González-Mozuelos P. Two-body correlations among particles confined to a spherical surface: Packing effects. J Chem Phys 2008; 128:014701. [DOI: 10.1063/1.2816558] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Vestergaard M, Hamada T, Takagi M. Using model membranes for the study of amyloid beta:lipid interactions and neurotoxicity. Biotechnol Bioeng 2008; 99:753-63. [DOI: 10.1002/bit.21731] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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45
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Affiliation(s)
- Ji-Xin Cheng
- Weldon School of Biomedical Engineering and Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
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