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Epand RM, Bach D, Wachtel E. In vitro determination of the solubility limit of cholesterol in phospholipid bilayers. Chem Phys Lipids 2016; 199:3-10. [DOI: 10.1016/j.chemphyslip.2016.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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2
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In vitro determination of the solubility limit of cholesterol in phospholipid bilayers. Chem Phys Lipids 2016. [DOI: 10.1016/j.chemphyslip.2016.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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3
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Ibarguren M, Bomans PHH, Ruiz-Mirazo K, Frederik PM, Alonso A, Goñi FM. Thermally-induced aggregation and fusion of protein-free lipid vesicles. Colloids Surf B Biointerfaces 2015; 136:545-52. [PMID: 26454544 DOI: 10.1016/j.colsurfb.2015.09.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 08/21/2015] [Accepted: 09/24/2015] [Indexed: 12/11/2022]
Abstract
Membrane fusion is an important phenomenon in cell biology and pathology. This phenomenon can be modeled using vesicles of defined size and lipid composition. Up to now fusion models typically required the use of chemical (polyethyleneglycol, cations) or enzymatic catalysts (phospholipases). We present here a model of lipid vesicle fusion induced by heat. Large unilamellar vesicles consisting of a phospholipid (dioleoylphosphatidylcholine), cholesterol and diacylglycerol in a 43:57:3 mol ratio were employed. In this simple system, fusion was the result of thermal fluctuations, above 60 °C. A similar system containing phospholipid and cholesterol but no diacylglycerol was observed to aggregate at and above 60 °C, in the absence of fusion. Vesicle fusion occurred under our experimental conditions only when (31)P NMR and cryo-transmission electron microscopy of the lipid mixtures used in vesicle preparation showed non-lamellar lipid phase formation (hexagonal and cubic). Non-lamellar structures are probably the result of lipid reassembly of the products of individual fusion events, or of fusion intermediates. A temperature-triggered mechanism of lipid reassembly might have occurred at various stages of protocellular evolution.
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Affiliation(s)
- Maitane Ibarguren
- Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Apto. 644, 48080 Bilbao, Spain.
| | - Paul H H Bomans
- Soft Matter CryoTEM Research Unit, Laboratory for Materials and Interface Chemistry, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
| | - Kepa Ruiz-Mirazo
- Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Apto. 644, 48080 Bilbao, Spain; Logic and Philosophy of Science Department, University of the Basque Country, Spain.
| | - Peter M Frederik
- Soft Matter CryoTEM Research Unit, Laboratory for Materials and Interface Chemistry, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
| | - Alicia Alonso
- Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Apto. 644, 48080 Bilbao, Spain.
| | - Félix M Goñi
- Unidad de Biofísica (Centro Mixto CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Apto. 644, 48080 Bilbao, Spain.
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4
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Losensky L, Chiantia S, Holland G, Laue M, Petran A, Liebscher J, Arbuzova A. Self-assembly of a cholesteryl-modified nucleoside into tubular structures from giant unilamellar vesicles. RSC Adv 2015. [DOI: 10.1039/c4ra11289j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Phosphatidylcholine-assisted self-assembly of cholesterylaminouridine into hollow needle-like structures was observed at room temperature.
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Affiliation(s)
- Luisa Losensky
- Humboldt-Universität zu Berlin
- Institut für Biologie
- 10115 Berlin
- Germany
| | | | | | | | - Anca Petran
- National Institute of Research and Development for Isotopic and Molecular Technologies
- RO-400293 Cluj-Napoca
- Romania
| | - Jürgen Liebscher
- National Institute of Research and Development for Isotopic and Molecular Technologies
- RO-400293 Cluj-Napoca
- Romania
| | - Anna Arbuzova
- Humboldt-Universität zu Berlin
- Institut für Biologie
- 10115 Berlin
- Germany
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5
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Mainali L, Raguz M, Subczynski WK. Formation of cholesterol bilayer domains precedes formation of cholesterol crystals in cholesterol/dimyristoylphosphatidylcholine membranes: EPR and DSC studies. J Phys Chem B 2013; 117:8994-9003. [PMID: 23834375 DOI: 10.1021/jp402394m] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Saturation-recovery EPR along with DSC were used to determine the cholesterol content at which pure cholesterol bilayer domains (CBDs) and cholesterol crystals begin to form in dimyristoylphosphatidylcholine (DMPC) membranes. To preserve compositional homogeneity throughout the membrane suspension, lipid multilamellar dispersions were prepared using a rapid solvent exchange method. The cholesterol content increased from 0 to 75 mol %. With spin-labeled cholesterol analogues, it was shown that the CBDs begin to form at ~50 mol % cholesterol. It was confirmed by DSC that the cholesterol solubility threshold for DMPC membranes is detected at ~66 mol % cholesterol. At levels above this cholesterol content, monohydrate cholesterol crystals start to form. The major finding is that the formation of CBDs precedes formation of cholesterol crystals. The region of the phase diagram for cholesterol contents between 50 and 66 mol % is described as a structured one-phase region in which CBDs have to be supported by the surrounding DMPC bilayer saturated with cholesterol. Thus, the phase boundary located at 66 mol % cholesterol separates the structured one-phase region (liquid-ordered phase of DMPC with CBDs) from the two-phase region where the structured liquid-ordered phase of DMPC coexists with cholesterol crystals. It is likely that CBDs are precursors of monohydrate cholesterol crystals.
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Affiliation(s)
- Laxman Mainali
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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6
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Bach D, Epand R, Epand R, Miller I, Wachtel E. The oxysterol 3β-hydroxy-5-oxo-5,6-secocholestan-6-al changes the phase behavior and structure of phosphatidylethanolamine–phosphatidylcholine mixtures. Chem Phys Lipids 2011; 164:672-9. [DOI: 10.1016/j.chemphyslip.2011.06.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 06/26/2011] [Accepted: 06/28/2011] [Indexed: 11/25/2022]
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7
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Chiu MH, Prenner EJ. Differential scanning calorimetry: An invaluable tool for a detailed thermodynamic characterization of macromolecules and their interactions. J Pharm Bioallied Sci 2011; 3:39-59. [PMID: 21430954 PMCID: PMC3053520 DOI: 10.4103/0975-7406.76463] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 10/05/2010] [Accepted: 10/19/2010] [Indexed: 11/04/2022] Open
Abstract
Differential Scanning Calorimetry (DSC) is a highly sensitive technique to study the thermotropic properties of many different biological macromolecules and extracts. Since its early development, DSC has been applied to the pharmaceutical field with excipient studies and DNA drugs. In recent times, more attention has been applied to lipid-based drug delivery systems and drug interactions with biomimetic membranes. Highly reproducible phase transitions have been used to determine values, such as, the type of binding interaction, purity, stability, and release from a drug delivery mechanism. This review focuses on the use of DSC for biochemical and pharmaceutical applications.
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Affiliation(s)
- Michael H Chiu
- Department of Biological Sciences, University of Calgary, T2N 1N4 Calgary, AB, Canada
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8
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Dittrich M, Heinze M, Wölk C, Funari SS, Dobner B, Möhwald H, Brezesinski G. Structure-Function Relationships of New Lipids Designed for DNA Transfection. Chemphyschem 2011; 12:2328-37. [DOI: 10.1002/cphc.201100065] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/29/2011] [Indexed: 11/12/2022]
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9
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X-ray and Neutron Scattering Studies of Lipid–Sterol Model Membranes. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1554-4516(10)11008-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023]
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11
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Raguz M, Widomska J, Dillon J, Gaillard ER, Subczynski WK. Physical properties of the lipid bilayer membrane made of cortical and nuclear bovine lens lipids: EPR spin-labeling studies. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1788:2380-8. [PMID: 19761756 PMCID: PMC2767447 DOI: 10.1016/j.bbamem.2009.09.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Revised: 08/24/2009] [Accepted: 09/06/2009] [Indexed: 11/15/2022]
Abstract
The physical properties of membranes derived from the total lipids extracted from the lens cortex and nucleus of a 2-year-old cow were investigated using EPR spin-labeling methods. Conventional EPR spectra and saturation-recovery curves show that spin labels detect a single homogenous environment in membranes made from cortical lipids. Properties of these membranes are very similar to those reported by us for membranes made of the total lipid extract of 6-month-old calf lenses (J. Widomska, M. Raguz, J. Dillon, E. R. Gaillard, W. K. Subczynski, Biochim. Biophys. Acta 1768 (2007) 1454-1465). However, in membranes made from nuclear lipids, two domains were detected by the EPR discrimination by oxygen transport method using the cholesterol analogue spin label and were assigned to the bulk phospholipid-cholesterol domain (PCD) and the immiscible cholesterol crystalline domain (CCD), respectively. Profiles of the order parameter, hydrophobicity, and the oxygen transport parameter are practically identical in the bulk PCD when measured for either the cortical or nuclear lipid membranes. In both membranes, lipids in the bulk PCD are strongly immobilized at all depths. Hydrophobicity and oxygen transport parameter profiles have a rectangular shape with an abrupt change between the C9 and C10 positions, which is approximately where the steroid ring structure of cholesterol reaches into the membrane. The permeability coefficient for oxygen, estimated at 35 degrees C, across the bulk PCD in both membranes is slightly lower than across the water layer of the same thickness. However, the evaluated upper limit of the permeability coefficient for oxygen across the CCD (34.4 cm/s) is significantly lower than across the water layer of the same thickness (85.9 cm/s), indicating that the CCD can significantly reduce oxygen transport in the lens nucleus.
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Affiliation(s)
- Marija Raguz
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Justyna Widomska
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - James Dillon
- Department of Ophthalmology, Columbia University, New York, New York 10032, USA
| | - Elizabeth R. Gaillard
- Department of Ophthalmology, Columbia University, New York, New York 10032, USA
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois, 60115, USA
| | - Witold K. Subczynski
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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12
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The oxidized form of cholesterol 3β-hydroxy-5-oxo-5,6-secocholestan-6-al induces structural and thermotropic changes in phospholipid membranes. Chem Phys Lipids 2009; 161:95-102. [DOI: 10.1016/j.chemphyslip.2009.07.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2009] [Accepted: 07/26/2009] [Indexed: 11/17/2022]
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13
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Ruozi B, Tosi G, Tonelli M, Bondioli L, Mucci A, Forni F, Vandelli MA. AFM phase imaging of soft-hydrated samples: A versatile tool to complete the chemical-physical study of liposomes. J Liposome Res 2009; 19:59-67. [DOI: 10.1080/08982100802584071] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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14
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Raguz M, Widomska J, Dillon J, Gaillard ER, Subczynski WK. Characterization of lipid domains in reconstituted porcine lens membranes using EPR spin-labeling approaches. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1778:1079-90. [PMID: 18298944 PMCID: PMC2711027 DOI: 10.1016/j.bbamem.2008.01.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 01/18/2008] [Accepted: 01/30/2008] [Indexed: 12/01/2022]
Abstract
The physical properties of membranes derived from the total lipid extract of porcine lenses before and after the addition of cholesterol were investigated using EPR spin-labeling methods. Conventional EPR spectra and saturation-recovery curves indicate that the spin labels detect a single homogenous environment in membranes before the addition of cholesterol. After the addition of cholesterol (when cholesterol-to-phospholipid mole to mole ratio of 1.55-1.80 was achieved), two domains were detected by the discrimination by oxygen transport method using a cholesterol analogue spin label. The domains were assigned to a bulk phospholipid-cholesterol bilayer made of the total lipid mixture and to a cholesterol crystalline domain. Because the phospholipid analogue spin labels cannot partition into the pure cholesterol crystalline domain, they monitor properties of the phospholipid-cholesterol domain outside the pure cholesterol crystalline domain. Profiles of the order parameter, hydrophobicity, and oxygen transport parameter are identical within experimental error in this domain when measured in the absence and presence of a cholesterol crystalline domain. This indicates that both domains, the phospholipid-cholesterol bilayer and the pure cholesterol crystalline domain, can be treated as independent, weakly interacting membrane regions. The upper limit of the oxygen permeability coefficient across the cholesterol crystalline domain at 35 degrees C had a calculated value of 42.5 cm/s, indicating that the cholesterol crystalline domain can significantly reduce oxygen transport to the lens center. This work was undertaken to better elucidate the major factors that determine membrane resistance to oxygen transport across the lens lipid membrane, with special attention paid to the cholesterol crystalline domain.
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Affiliation(s)
- Marija Raguz
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Justyna Widomska
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - James Dillon
- Department of Ophthalmology, Columbia University, New York, New York 10032, USA
| | - Elizabeth R. Gaillard
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois, 60115,USA
| | - Witold K. Subczynski
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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15
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Zhang Y, Bradshaw-Pierce EL, Delille A, Gustafson DL, Anchordoquy TJ. In vivo comparative study of lipid/DNA complexes with different in vitro serum stability: effects on biodistribution and tumor accumulation. J Pharm Sci 2008; 97:237-50. [PMID: 17721944 DOI: 10.1002/jps.21076] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To evaluate the in vivo biodistribution and expression of DOTAP-Chol/DNA complexes (lipoplexes) with different in vitro serum stability, quantitative real-time PCR, in vitro luciferase expression and whole body luminescence imaging were used. In general, less tissue biodistribution, lower luciferase expression and whole body luminescence were observed for DOTAP:Chol (mol/mol 1:4)/DNA lipoplexes which had higher in vitro serum stability as compared to DOTAP:Chol (mol/mol 1:1)/DNA lipoplexes. Plasmid DNA biodistribution and expression were mainly confined to the lungs, and the results suggest that in vitro serum stability may serve as a predictor of transfection in the lung. No correlation between plasmid DNA tissue biodistribution and gene expression was observed by simultaneous determination of the level of plasmid DNA tissue biodistribution and gene expression. While high doses of the formulation possessing increased in vitro serum stability did exhibit reduced entrapment in the lung, no corresponding increase in the plasmid levels of other tissues was observed. However, this formulation did show increased accumulation in tumors that was not further enhanced by PEGylation.
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Affiliation(s)
- Ye Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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16
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Differential modulation of membrane structure and fluctuations by plant sterols and cholesterol. Biophys J 2008; 94:3935-44. [PMID: 18234811 DOI: 10.1529/biophysj.107.123224] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have studied the concentration and temperature dependent influence of cholesterol, stigmasterol, and sitosterol on the global structure and the bending fluctuations of fluid dimyristoyl phosphatidylcholine and palmitoyl oleoyl phosphatidylcholine bilayers applying small-angle x-ray scattering, as well as dilatometry and ultrasound velocimetry. Independent of the lipid matrix, cholesterol was found to be most efficient in modulating bilayer thickness and elasticity, followed by sitosterol and stigmasterol. This can be attributed to the additional ethyl groups and double bond at the C(17) alkyl side-chain of the two plant sterols. Hence, it seems that some flexibility of the sterol hydrocarbon chain is needed to accommodate within the lipid bilayer. In addition, we did not observe two populations of membranes within the putative liquid-ordered/liquid-disordered phase coexistence regime of binary sterol/lipid mixtures. Instead, the diffraction patterns could be interpreted in terms of a uniform phase. This lends further support to the idea of compositional fluctuations of unstable sterol rich domains recently brought up by fluorescence microscopy experiments, which contrasts the formation of stable domains within the miscibility gap of binary lipid/sterol mixtures.
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17
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Pineau L, Bonifait L, Berjeaud JM, Alimardani-Theuil P, Bergès T, Ferreira T. A lipid-mediated quality control process in the Golgi apparatus in yeast. Mol Biol Cell 2007; 19:807-21. [PMID: 18094052 DOI: 10.1091/mbc.e07-06-0600] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
When heme biosynthesis is disrupted, the yeast Saccharomyces cerevisiae becomes unable to synthesize its major sterol, ergosterol, and desaturate fatty acids. We took advantage of this physiological peculiarity to evaluate the consequences of ergosterol and/or unsaturated fatty acid (UFA) depletions on the biogenesis of a model polytopic plasma membrane protein, the uracil permease Fur4p. We show that under UFA shortage, which results in low amounts of diunsaturated phospholipid species, and under ergosterol depletion, Fur4p is prematurely routed from the Golgi apparatus to the vacuolar lumen in a process that requires the ubiquitin ligase Rsp5p. Interestingly, this diversion is not correlated to Fur4p exclusion from detergent-resistant membranes. In an independent set of experiments, we show that Fur4p targeting to the plasma membrane depends on phosphatidylethanolamine amounts and more specifically on the propensity of this phospholipid to form a hexagonal phase. In light of recent literature, we propose a model in which ergosterol and diunsaturated phospholipid species maintain optimal membrane curvature for Fur4p to evade the Golgi quality control process and to be properly delivered to its normal destination.
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Affiliation(s)
- Ludovic Pineau
- Université de Poitiers, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6161 Transport des assimilats 86022 Poitiers Cedex, France
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18
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Tenchov BG, MacDonald RC, Siegel DP. Cubic phases in phosphatidylcholine-cholesterol mixtures: cholesterol as membrane "fusogen". Biophys J 2006; 91:2508-16. [PMID: 16829556 PMCID: PMC1562400 DOI: 10.1529/biophysj.106.083766] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
X-ray diffraction reveals that mixtures of some unsaturated phosphatidylcholines (PCs) with cholesterol (Chol) readily form inverted bicontinuous cubic phases that are stable under physiological conditions. This effect was studied in most detail for dioleoyl PC/Chol mixtures with molar ratios of 1:1 and 3:7. Facile formation of Im3m and Pn3m phases with lattice constants of 30-50 nm and 25-30 nm, respectively, took place in phosphate-buffered saline, in sucrose solution, and in water near the temperature of the Lalpha-HII transition of the mixtures, as well as during cooling of the HII phase. Once formed, the cubic phases displayed an ability to supercool and replace the initial Lalpha phase over a broad range of physiological temperatures. Conversion into stable cubic phases was also observed for mixtures of Chol with dilinoleoyl PC but not for mixtures with palmitoyl-linoleoyl PC or palmitoyl-oleoyl PC, for which only transient cubic traces were recorded at elevated temperatures. A saturated, branched-chain PC, diphytanoyl PC, also displayed a cubic phase in mixture with Chol. Unlike the PEs, the membrane PCs are intrinsically nonfusogenic lipids: in excess water they only form lamellar phases and not any of the inverted phases on their own. Thus, the finding that Chol induces cubic phases in mixtures with unsaturated PCs may have important implications for its role in fusion. In ternary mixtures, saturated PCs and sphingomyelin are known to separate into liquid-ordered domains along with Chol. Our results thus suggest that unsaturated PCs, which are excluded from these domains, could form fusogenic domains with Chol. Such a dual role of Chol may explain the seemingly paradoxical ability of cell membranes to simultaneously form rigid, low-curvature raft-like patches while still being able to undergo facile membrane fusion.
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Affiliation(s)
- Boris G Tenchov
- Northwestern University, Department of Biochemistry, Molecular Biology and Cell Biology, Evanston, Illinois 60208, USA.
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19
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Epand RM. Detecting the presence of membrane domains using DSC. Biophys Chem 2006; 126:197-200. [PMID: 16730877 DOI: 10.1016/j.bpc.2006.05.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Accepted: 05/10/2006] [Indexed: 11/24/2022]
Abstract
Both biological and model liposomal membranes have unequal distribution of molecular components in the plane of the membrane. There is increasing interest to determine the composition and properties of membrane domains enriched with specific molecular components. Several methodologies have been applied to study this. Each has its own advantages and provides a particular kind of information. In the present article, we will focus on the application of differential scanning calorimetry to the determination of the distribution of molecules into membrane domains with particular emphasis on protein and peptide-induced domain formation.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University Health Sciences Centre, Hamilton, ON, Canada L8N 3Z5.
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Delobel A, Touboul D, Laprévote O. Structural characterization of phosphatidylcholines by atmospheric pressure photoionization mass spectrometry. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2005; 11:409-17. [PMID: 16204808 DOI: 10.1255/ejms.760] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The potential of atmospheric pressure photoionization was investigated for the structural analysis of phosphatidylcholine lipids (PCs). [M+H]+ ions of high abundance were obtained, along with several fragment ions. Three of these dissociation products corresponded to quite unusual fragmentation pathways but allowed the determination of both the nature and the position on the glycerol backbone (sn-1 or sn-2) of the fatty acyl chains. The loss of a methyl group from the choline head was also observed. These results suggest a complex ionization mechanism in APPI. However, this method proved to be very powerful for the rapid structural analysis of PC species without using MS/MS experiments.
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Affiliation(s)
- Arnaud Delobel
- Laboratoire de Spectrométrie de Masse, Institut de Chimie des Substances Naturelles, (ICSN-CNRS), Av. de la Terrasse, F-91198 Gif-Sur-Yvette Cedex, France
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