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Roberts JA, Rosales CA, Wasslen KV, Radnoff AS, Godbout E, Diallo JS, Manthorpe JM, Smith JC. An In Silico Database for Automated Feature Identification of High-Resolution Tandem Mass Spectrometry 13C-Trimethylation Enhancement Using Diazomethane ( 13C-TrEnDi)-Modified Lipid Data. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:2722-2730. [PMID: 37929927 DOI: 10.1021/jasms.3c00273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
13C-Trimethylation enhancement using diazomethane (13C-TrEnDi) is a chemical derivatization technique that uses 13C-labeled diazomethane to increase mass spectrometry (MS) signal intensities for phosphatidylcholine (PC) and phosphatidylethanolamine (PE) lipid classes, both of which are of major interest in biochemistry. In silico mass spectrometry databases have become mainstays in lipidomics experiments; however, 13C-TrEnDi-modified PC and PE species have altered m/z and fragmentation patterns from their native counterparts. To build a database of 13C-TrEnDi-modified PC and PE species, a lipid extract from nutritional yeast was derivatized and fragmentation spectra of modified PC and PE species were mined using diagnostic fragmentation filtering by searching 13C-TrEnDi-modified headgroups with m/z 199 (PC) and 202 (PE). Identities of 25 PC and 10 PE species were assigned after comparing to predicted masses from the Lipid Maps Structure Database with no false positive identifications observed; neutral lipids could still be annotated after derivatization. Collision energies from 16 to 52 eV were examined, resulting in three additional class-specific fragment ions emerging, as well as a combined sn-1/sn-2 fragment ion, allowing sum-composition level annotations to be assigned. Using the Lipid Blast templates, a NIST-compatible 13C-TrEnDi database was produced based on fragmentation spectra observed at 36 eV and tested on HEK 293T cell lipid extracts, identifying 47 PC and 24 PE species, representing a 1.8-fold and 2.2-fold increase in annotations, respectively. The 13C-TrEnDi database is freely available, MS vendor-independent, and widely compatible with MS data processing pipelines, increasing the throughput and accessibility of TrEnDi for lipidomics applications.
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Affiliation(s)
- Joshua A Roberts
- Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6, Canada
| | - Christian A Rosales
- Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6, Canada
| | - Karl V Wasslen
- Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6, Canada
- Carleton Mass Spectrometry Centre, Carleton University, Ottawa, Ontario K1S 5B6, Canada
| | - Angela S Radnoff
- Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6, Canada
| | - Elena Godbout
- Centre for Cancer Therapeutics, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario K1H 8L6, Canada
| | - Jean-Simon Diallo
- Centre for Cancer Therapeutics, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario K1H 8L6, Canada
| | - Jeffrey M Manthorpe
- Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6, Canada
- Carleton Mass Spectrometry Centre, Carleton University, Ottawa, Ontario K1S 5B6, Canada
| | - Jeffrey C Smith
- Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6, Canada
- Carleton Mass Spectrometry Centre, Carleton University, Ottawa, Ontario K1S 5B6, Canada
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2
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Boratto FA, Lages EB, Loures CMC, Sabino AP, Malachias A, Townsend DM, Branco De Barros AL, Miranda Ferreira LA, Amaral Leite E. Alpha-tocopheryl succinate and doxorubicin-loaded liposomes improve drug uptake and tumor accumulation in a murine breast tumor model. Biomed Pharmacother 2023; 165:115034. [PMID: 37356372 PMCID: PMC10720879 DOI: 10.1016/j.biopha.2023.115034] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 06/10/2023] [Accepted: 06/13/2023] [Indexed: 06/27/2023] Open
Abstract
Liposomes composed of a rigid bilayer have high plasma stability; however, they can be challenged in efficacy due to complications in releasing the encapsulated drug as well as being internalized by the tumor cell. On the other hand, fusogenic liposomes may fuse with the plasmatic membrane and release encapsulated material directly into the cytoplasm. In a previous study, fusogenic liposomes composed of alpha-tocopheryl succinate (TS) and doxorubicin (DOX) were developed (pHSL-TS-DOX). These stabilized tumor growth and reduced toxicity compared to a commercial formulation. In the present study, we investigated whether cellular uptake or DOX accumulation in the tumor could justify the better performance of the pHSL-TS-DOX formulation. Release, deformability, and DOX plasmatic concentration studies were also carried out. pHSL-TS-DOX showed an adequate release profile and demonstrated characteristics of a deformable formulation. Data from apoptosis, cell cycle, and nuclear morphology studies have shown that the induction of cell death caused by pHSL-TS-DOX occurred more quickly. Higher DOX cellular uptake and tumor accumulation were observed when pHSL-TS-DOX was administered, demonstrating better drug delivery capacity. Therefore, better DOX uptake as well as tumor accumulation explain the great antitumor activity previously demonstrated for this formulation.
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Affiliation(s)
- Fernanda A Boratto
- Department of Pharmaceutical Products, Faculty of Pharmacy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Eduardo B Lages
- Department of Pharmaceutical Products, Faculty of Pharmacy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Cristina M C Loures
- Department of Clinical and Toxicological Analyses, Faculty of Pharmacy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Adriano P Sabino
- Department of Clinical and Toxicological Analyses, Faculty of Pharmacy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Angelo Malachias
- Department of Physics, Institute of Exact Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Danyelle M Townsend
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Andre Luis Branco De Barros
- Department of Clinical and Toxicological Analyses, Faculty of Pharmacy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
| | - Lucas Antonio Miranda Ferreira
- Department of Pharmaceutical Products, Faculty of Pharmacy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Elaine Amaral Leite
- Department of Pharmaceutical Products, Faculty of Pharmacy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
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Prada D, Rexrode K, Kalia V, Kooperberg C, Reiner A, Balasubramanian R, Wu HC, Miller G, Lonita-Laza I, Crandall C, Cantu-de-Leon D, Liao D, Yanosky J, Stewart J, Whitsel E, Baccarelli A. Metabolomic Evaluation of Air Pollution-related Bone Damage and Potential Mediation. RESEARCH SQUARE 2023:rs.3.rs-2652887. [PMID: 37034583 PMCID: PMC10081369 DOI: 10.21203/rs.3.rs-2652887/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Ambient air pollution has been associated with bone damage. However, no studies have evaluated the metabolomic response to air pollutants and its potential influence on bone health in postmenopausal women. We analyzed data from WHI participants with plasma samples. Whole-body, total hip, femoral neck, and spine BMD at enrollment and follow-up (Y1, Y3, Y6). Daily particulate matter NO, NO2, PM10 and SO2 were averaged over 1-, 3-, and 5-year periods before metabolomic assessments. Statistical analyses included multivariable-adjusted linear mixed models, pathways analyses, and mediation modeling. NO, NO2, and SO2, but not PM10, were associated with taurine, inosine, and C38:4 phosphatidylethanolamine (PE), at all averaging periods. We found a partial mediation of C38:4 PE in the association between 1-year average NO and lumbar spine BMD (p-value: 0.032). This is the first study suggesting that a PE may partially mediate air pollution-related bone damage in postmenopausal women.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Jeff Yanosky
- Pennsylvania State University College of Medicine
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4
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Billah MM, Or Rashid MM, Ahmed M, Yamazaki M. Antimicrobial peptide magainin 2-induced rupture of single giant unilamellar vesicles comprising E. coli polar lipids. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184112. [PMID: 36567034 DOI: 10.1016/j.bbamem.2022.184112] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/05/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022]
Abstract
Most antimicrobial peptides (AMPs) damage the cell membrane of bacterial cells and induce rapid leakage of the internal cell contents, which is a main cause of their bactericidal activity. One of the AMPs, magainin 2 (Mag), forms nanopores in giant unilamellar vesicles (GUVs) comprising phosphatidylcholine (PC) and phosphatidylglycerol (PG), inducing leakage of fluorescent probes. In this study, to elucidate the Mag-induced pore formation in lipid bilayer region in E. coli cell membrane, we examined the interaction of Mag with single GUVs comprising E. coli polar lipids (E. coli-lipid-GUVs). First, we investigated the Mag-induced leakage of a fluorescent probe AF488 from single E. coli-lipid-GUVs, and found that Mag caused rupture of GUVs, inducing rapid AF488 leakage. The rate constant of Mag-induced GUV rupture increased with the Mag concentration. Using fluorescence microscopy with a time resolution of 5 ms, we revealed the GUV rupture process: first, a small micropore was observed in the GUV membrane, then the pore radius increased within 50 ms without changing the GUV diameter, the thickness of the membrane at the pore rim concomitantly increased, and eventually membrane aggregates were formed. Mag bound to only the outer monolayer of the GUV before GUV rupture, which increased the area of the GUV bilayer. We also examined the physical properties of E. coli-lipid-GUVs themselves. We found that the rate constant of the constant tension-induced rupture of E. coli-lipid-GUVs was higher than that of PG/PC-GUVs. Based on these results, we discussed the Mag-induced rupture of E. coli-lipid-GUVs and its mechanism.
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Affiliation(s)
- Md Masum Billah
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Md Mamun Or Rashid
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Marzuk Ahmed
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Masahito Yamazaki
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan; Nanomaterials Research Division, Research Institute of Electronics, Shizuoka University, Shizuoka 422-8529, Japan; Department of Physics, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan.
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5
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Heinonen S, Lautala S, Koivuniemi A, Bunker A. Insights into the behavior of unsaturated diacylglycerols in mixed lipid bilayers in relation to protein kinase C activation-A molecular dynamics simulation study. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183961. [PMID: 35568204 DOI: 10.1016/j.bbamem.2022.183961] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
The lipid second messenger diacylglycerol (DAG) is known for its involvement in many types of cellular signaling, especially as an endogenous agonist for protein kinase C (PKC). Evidence has emerged that the degree of saturation of the DAG molecules can affect PKC activation. DAG molecules with different acyl chain saturation have not only been observed to induce varying extents of PKC activation, but also to express selectivity towards different PKC isozymes. Both qualities are important for precise therapeutic activation of PKC; understanding DAG behavior at the molecular level in different environments has much potential in the development of drugs to target PKC. We used molecular dynamics simulations to study the behavior of two different unsaturated DAG species in lipid environments with varying degrees of unsaturation. We focus on phosphatidylethanolamine (PE) instead of phosphatidylcholine (PC) to more accurately model the relevant biomembranes. The effect of cholesterol (CHOL) on these systems was also explored. We found that both high level of unsaturation in the acyl chains of the DAG species and presence of CHOL in the surrounding membrane increase DAG molecule availability at the lipid-water interface. This can partially explain the previously observed differences in PKC activation strength and specificity, the complete mechanism is, however, likely to be more complex. Our simulations coupled with the current understanding of lipids highlight the need for more simulations of biologically accurate lipid environments in order to determine the correct correlations between molecular mechanisms and biological behavior when studying PKC activation.
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Affiliation(s)
- Suvi Heinonen
- Drug Research Program, Division of Pharmaceutical Biosciences, University of Helsinki, FI-00014, Helsinki, Finland
| | - Saara Lautala
- Drug Research Program, Division of Pharmaceutical Biosciences, University of Helsinki, FI-00014, Helsinki, Finland.
| | - Artturi Koivuniemi
- Drug Research Program, Division of Pharmaceutical Biosciences, University of Helsinki, FI-00014, Helsinki, Finland
| | - Alex Bunker
- Drug Research Program, Division of Pharmaceutical Biosciences, University of Helsinki, FI-00014, Helsinki, Finland
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6
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Dymond MK. Lipid monolayer spontaneous curvatures: A collection of published values. Chem Phys Lipids 2021; 239:105117. [PMID: 34265278 DOI: 10.1016/j.chemphyslip.2021.105117] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 07/03/2021] [Accepted: 07/09/2021] [Indexed: 11/24/2022]
Abstract
Lipid monolayer spontaneous curvatures (or lipid intrinsic curvatures) are one of several material properties of lipids that enable the stored curvature elastic energy in a lipid aggregate to be determined. Stored curvature elastic energy is important since it can modulate the function of membrane proteins and plays a role in the regulatory pathways of phospholipid homeostasis. Due to the large number of different lipid molecules that might theoretically exist in nature, very few lipid spontaneous curvatures have been determined. Herein the values of lipid spontaneous curvatures that exist in the literature are collected, alongside key experimental details. Where possible, trends in the data are discussed and finally, obvious gaps in the knowledge are signposted.
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Affiliation(s)
- Marcus K Dymond
- Chemistry Research and Enterprise Group, School of Pharmacy and Biomolecular Sciences, Huxley Building, University of Brighton, BN2 4GL, United Kingdom.
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7
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Tarasenko D, Meinecke M. Protein-dependent membrane remodeling in mitochondrial morphology and clathrin-mediated endocytosis. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:295-306. [PMID: 33527201 PMCID: PMC8071792 DOI: 10.1007/s00249-021-01501-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 01/04/2021] [Accepted: 01/13/2021] [Indexed: 11/30/2022]
Abstract
Cellular membranes can adopt a plethora of complex and beautiful shapes, most of which are believed to have evolved for a particular physiological reason. The closely entangled relationship between membrane morphology and cellular physiology is strikingly seen in membrane trafficking pathways. During clathrin-mediated endocytosis, for example, over the course of a minute, a patch of the more or less flat plasma membrane is remodeled into a highly curved clathrin-coated vesicle. Such vesicles are internalized by the cell to degrade or recycle plasma membrane receptors or to take up extracellular ligands. Other, steadier, membrane morphologies can be observed in organellar membranes like the endoplasmic reticulum or mitochondria. In the case of mitochondria, which are double membrane-bound, ubiquitous organelles of eukaryotic cells, especially the mitochondrial inner membrane displays an intricated ultrastructure. It is highly folded and consequently has a much larger surface than the mitochondrial outer membrane. It can adopt different shapes in response to cellular demands and changes of the inner membrane morphology often accompany severe diseases, including neurodegenerative- and metabolic diseases and cancer. In recent years, progress was made in the identification of molecules that are important for the aforementioned membrane remodeling events. In this review, we will sum up recent results and discuss the main players of membrane remodeling processes that lead to the mitochondrial inner membrane ultrastructure and in clathrin-mediated endocytosis. We will compare differences and similarities between the molecular mechanisms that peripheral and integral membrane proteins use to deform membranes.
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Affiliation(s)
- Daryna Tarasenko
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
- Göttinger Zentrum für Molekulare Biowissenschaften - GZMB, 37077, Göttingen, Germany.
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8
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Effects of Phosphoethanolamine Supplementation on Mitochondrial Activity and Lipogenesis in a Caffeine Ingestion Caenorhabditis elegans Model. Nutrients 2020; 12:nu12113348. [PMID: 33143181 PMCID: PMC7694071 DOI: 10.3390/nu12113348] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/24/2020] [Accepted: 10/29/2020] [Indexed: 12/12/2022] Open
Abstract
Caffeine intake is strongly linked to lipid metabolism. We previously reported the age-dependent physiological effects of caffeine intake in a Caenorhabditis elegans model. Since nutritional status can actively influence metabolism and overall health, in this study, we evaluated the effect of caffeine intake on lipid metabolism in adult-stage C. elegans. We found that, in C. elegans, fat storage and the level of phosphoethanolamine (PE) were significantly reduced with caffeine intake. In addition, mitochondrial activity decreased and mitochondrial morphology was disrupted, and the expression of oxidative stress response genes, hsp-6, gst-4, and daf-16, was induced by caffeine intake. Furthermore, the level of an energy metabolism sensor, phospho-AMP-activated protein kinase, was increased, whereas the expression of the sterol regulatory element binding protein gene and its target stearoyl-CoA desaturase genes, fat-5, -6, and -7, was decreased with caffeine intake. These findings suggest that caffeine intake causes mitochondrial dysfunction and reduces lipogenesis. Interestingly, these changes induced by caffeine intake were partially alleviated by PE supplementation, suggesting that the reduction in mitochondrial activity and lipogenesis is in part because of the low PE level, and proper dietary supplementation can improve organelle integrity.
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9
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Koseki K, Suzuki H. Deformation Dynamics of Giant Unilamellar Vesicles in the Large Surface-to-Volume Ratio Regime: The Emergence of Neuron-like Morphology. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6238-6244. [PMID: 32364747 DOI: 10.1021/acs.langmuir.0c00872] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Deformation of liposomes, or lipid vesicles, has been investigated extensively in terms of the thermodynamic equilibrium of the bending energy of the lipid bilayer membrane. However, the range of such deformation in previous literature has been limited within the moderate surface-to-volume ratio of the vesicles, in which axisymmetric shapes are dominant. Here, we show that neuron-like morphology, in which many lipid tubes extend radially from the mother vesicle, becomes dominant upon the slow osmotic shrinkage of giant unilamellar vesicles (GUVs) initially larger than several tens of micrometers. We show that, in the time-lapse confocal imaging, the emergence of lipid tubes is initiated from the instability that appeared along the annular rim of the flat stomatocyte shape. Since these deformation dynamics into the neuron-like morphology resemble that of the milk-crown formation in liquid splashing, we discuss that the Rayleigh-Plateau capillary instability drives this transformation into a nonaxisymmetric shape.
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Affiliation(s)
- Kaoru Koseki
- Department of Precision Mechanics, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Hiroaki Suzuki
- Department of Precision Mechanics, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
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10
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Wang R, Li B, Lam SM, Shui G. Integration of lipidomics and metabolomics for in-depth understanding of cellular mechanism and disease progression. J Genet Genomics 2019; 47:69-83. [PMID: 32178981 DOI: 10.1016/j.jgg.2019.11.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/19/2019] [Accepted: 11/25/2019] [Indexed: 12/17/2022]
Abstract
Mass spectrometry (MS)-based omics technologies are now widely used to profile small molecules in multiple matrices to confer comprehensive snapshots of cellular metabolic phenotypes. The metabolomes of cells, tissues, and organisms comprise a variety of molecules including lipids, amino acids, sugars, organic acids, and so on. Metabolomics mainly focus on the hydrophilic classes, while lipidomics has emerged as an independent omics owing to the complexities of the organismal lipidomes. The potential roles of lipids and small metabolites in disease pathogenesis have been widely investigated in various human diseases, but system-level understanding is largely lacking, which could be partly attributed to the insufficiency in terms of metabolite coverage and quantitation accuracy in current analytical technologies. While scientists are continuously striving to develop high-coverage omics approaches, integration of metabolomics and lipidomics is becoming an emerging approach to mechanistic investigation. Integration of metabolome and lipidome offers a complete atlas of the metabolic landscape, enabling comprehensive network analysis to identify critical metabolic drivers in disease pathology, facilitating the study of interconnection between lipids and other metabolites in disease progression. In this review, we summarize omics-based findings on the roles of lipids and metabolites in the pathogenesis of selected major diseases threatening public health. We also discuss the advantages of integrating lipidomics and metabolomics for in-depth understanding of molecular mechanism in disease pathogenesis.
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Affiliation(s)
- Raoxu Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100101, China
| | - Bowen Li
- Lipidall Technologies Company Limited, Changzhou, 213000, China
| | - Sin Man Lam
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China; Lipidall Technologies Company Limited, Changzhou, 213000, China.
| | - Guanghou Shui
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100101, China.
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11
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Pohl EE, Jovanovic O. The Role of Phosphatidylethanolamine Adducts in Modification of the Activity of Membrane Proteins under Oxidative Stress. Molecules 2019; 24:molecules24244545. [PMID: 31842328 PMCID: PMC6943717 DOI: 10.3390/molecules24244545] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 12/09/2019] [Accepted: 12/10/2019] [Indexed: 12/11/2022] Open
Abstract
Reactive oxygen species (ROS) and their derivatives, reactive aldehydes (RAs), have been implicated in the pathogenesis of many diseases, including metabolic, cardiovascular, and inflammatory disease. Understanding how RAs can modify the function of membrane proteins is critical for the design of therapeutic approaches in the above-mentioned pathologies. Over the last few decades, direct interactions of RA with proteins have been extensively studied. Yet, few studies have been performed on the modifications of membrane lipids arising from the interaction of RAs with the lipid amino group that leads to the formation of adducts. It is even less well understood how various multiple adducts affect the properties of the lipid membrane and those of embedded membrane proteins. In this short review, we discuss a crucial role of phosphatidylethanolamine (PE) and PE-derived adducts as mediators of RA effects on membrane proteins. We propose potential PE-mediated mechanisms that explain the modulation of membrane properties and the functions of membrane transporters, channels, receptors, and enzymes. We aim to highlight this new area of research and to encourage a more nuanced investigation of the complex nature of the new lipid-mediated mechanism in the modification of membrane protein function under oxidative stress.
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12
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Picca A, Calvani R, Landi G, Marini F, Biancolillo A, Gervasoni J, Persichilli S, Primiano A, Urbani A, Bossola M, Bentivoglio AR, Cesari M, Landi F, Bernabei R, Marzetti E, Lo Monaco MR. Circulating amino acid signature in older people with Parkinson's disease: A metabolic complement to the EXosomes in PArkiNson Disease (EXPAND) study. Exp Gerontol 2019; 128:110766. [PMID: 31666195 DOI: 10.1016/j.exger.2019.110766] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/18/2019] [Accepted: 10/25/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND AIM Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder in old age. Neurotoxicity of dopaminergic neurons triggered by aggregation of misfolded α-synuclein is a major pathogenic trait of PD. However, growing evidence indicates that peripheral processes, including metabolic changes, may precede and contribute to neurodegeneration. The present study was undertaken to identify a metabolic signature of PD through the quantification of serum amino acids and derivatives. PARTICIPANTS AND METHODS Twenty older adults with PD (11 men and 9 women; mean age 73.1 ± 10.2 years) and 30 age-matched controls (14 men and 16 women; mean age 74.6 ± 4.3 years) were enrolled. A panel of 37 serum amino acids and derivatives was assessed by ultra-performance liquid chromatography/mass spectrometry. Partial least squares - discriminant analysis (PLS-DA) followed by double cross-validation was used to characterize the relationship between amino acid profiles and PD. RESULTS The optimal complexity of the PLS-DA model was found to be three latent variables. The proportion of correct classifications was 99.3 ± 2.5% for participants with PD and 94.7 ± 3.0% for non-PD controls. Higher levels of β-amino butyric acid, cystine, ornithine, phosphoethanolamine, and proline defined the circulating amino acid profile of older people with PD. Controls were characterized by higher concentrations of 3-methyl-histidine, citrulline, and serine. CONCLUSION Our findings indicate the existence of a distinct metabotype in older persons with PD. Future studies will have to establish whether changes in amino acid metabolism are involved in the pathogenesis of PD. This knowledge may be harnessed to identify novel disease biomarkers as well as new targets for interventions.
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Affiliation(s)
- Anna Picca
- Università Cattolica del Sacro Cuore, Institute of Internal Medicine and Geriatrics, Rome, Italy; Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Riccardo Calvani
- Università Cattolica del Sacro Cuore, Institute of Internal Medicine and Geriatrics, Rome, Italy; Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Giovanni Landi
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Federico Marini
- Department of Chemistry, Sapienza Università di Roma, Rome, Italy
| | - Alessandra Biancolillo
- Department of Chemistry, Sapienza Università di Roma, Rome, Italy; Department of Physical and Chemical Sciences, University of L'Aquila, Italy
| | - Jacopo Gervasoni
- Università Cattolica del Sacro Cuore, Institute of Internal Medicine and Geriatrics, Rome, Italy; Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Silvia Persichilli
- Università Cattolica del Sacro Cuore, Institute of Internal Medicine and Geriatrics, Rome, Italy; Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Aniello Primiano
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Andrea Urbani
- Università Cattolica del Sacro Cuore, Institute of Internal Medicine and Geriatrics, Rome, Italy; Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Maurizio Bossola
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy; Università Cattolica del Sacro Cuore, Institute of Clinical Surgery, Rome, Italy
| | - Anna Rita Bentivoglio
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy; Università Cattolica del Sacro Cuore, Institute of Neurology, Rome, Italy
| | - Matteo Cesari
- Department of Clinical Sciences and Community Health, Università di Milano, Milan, Italy; Geriatric Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesco Landi
- Università Cattolica del Sacro Cuore, Institute of Internal Medicine and Geriatrics, Rome, Italy; Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Roberto Bernabei
- Università Cattolica del Sacro Cuore, Institute of Internal Medicine and Geriatrics, Rome, Italy; Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy.
| | - Emanuele Marzetti
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy.
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13
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Vance JE. Historical perspective: phosphatidylserine and phosphatidylethanolamine from the 1800s to the present. J Lipid Res 2018; 59:923-944. [PMID: 29661786 DOI: 10.1194/jlr.r084004] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/12/2018] [Indexed: 12/17/2022] Open
Abstract
This article provides a historical account of the discovery, chemistry, and biochemistry of two ubiquitous phosphoglycerolipids, phosphatidylserine (PS) and phosphatidylethanolamine (PE), including the ether lipids. In addition, the article describes the biosynthetic pathways for these phospholipids and how these pathways were elucidated. Several unique functions of PS and PE in mammalian cells in addition to their ability to define physical properties of membranes are discussed. For example, the translocation of PS from the inner to the outer leaflet of the plasma membrane of cells occurs during apoptosis and during some other specific physiological processes, and this translocation is responsible for profound life-or-death events. Moreover, mitochondrial function is severely impaired when the PE content of mitochondria is reduced below a threshold level. The discovery and implications of the existence of membrane contact sites between the endoplasmic reticulum and mitochondria and their relevance for PS and PE metabolism, as well as for mitochondrial function, are also discussed. Many of the recent advances in these fields are due to the use of isotope labeling for tracing biochemical pathways. In addition, techniques for disruption of specific genes in mice are now widely used and have provided major breakthroughs in understanding the roles and metabolism of PS and PE in vivo.
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Affiliation(s)
- Jean E Vance
- Department of Medicine and Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
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14
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Horibata Y, Elpeleg O, Eran A, Hirabayashi Y, Savitzki D, Tal G, Mandel H, Sugimoto H. EPT1 (selenoprotein I) is critical for the neural development and maintenance of plasmalogen in humans. J Lipid Res 2018; 59:1015-1026. [PMID: 29500230 DOI: 10.1194/jlr.p081620] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 03/01/2018] [Indexed: 11/20/2022] Open
Abstract
Ethanolamine phosphotransferase (EPT)1, also known as selenoprotein 1 (SELENOI), is an enzyme that transfers phosphoethanolamine from cytidine diphosphate-ethanolamine to lipid acceptors to produce ethanolamine glycerophospholipids, such as diacyl-linked phosphatidylethanolamine (PE) and ether-linked plasmalogen [1-alkenyl-2-acyl-glycerophosphoethanolamine (plasmenyl-PE)]. However, to date there has been no analysis of the metabolomic consequences of the mutation of EPT1 on the concentration of ethanolamine glycerophospholipids in mammalian cells. We studied a patient with severe complicated hereditary spastic paraplegia, sensorineural-deafness, blindness, and seizures. Neuroimaging revealed hypomyelination, followed by brain atrophy mainly in the cerebellum and brainstem. Using whole exome sequencing, we identified a novel EPT1 mutation (exon skipping). In vitro EPT activity, as well as the rate of biosynthesis of ethanolamine glycerophospholipids, was markedly reduced in cultures of the patient's skin fibroblasts. Quantification of phospholipids by LC-MS/MS demonstrated reduced levels of several PE species with polyunsaturated fatty acids, such as 38:6, 38:4, 40:6, 40:5, and 40:4. Notably, most plasmenyl-PE species were significantly decreased in the patient's cells, whereas most plasmanylcholine [1-alkyl-2-acyl-glycerophosphocholine (plasmanyl-PC)] species were increased. Similar findings regarding decreased plasmenyl-PE and increased plasmanyl-PC were obtained using EPT1-KO HeLa cells. Our data demonstrate for the first time the indispensable role of EPT1 in the myelination process and neurodevelopment, and in the maintenance of normal homeostasis of ether-linked phospholipids in humans.
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Affiliation(s)
- Yasuhiro Horibata
- Department of Biochemistry, Dokkyo Medical University School of Medicine, Mibu, Tochigi, Japan
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ayelet Eran
- Department of Diagnostic Imaging, Rambam Health Care Campus, Haifa, Israel
| | - Yoshio Hirabayashi
- Molecular Membrane Neuroscience, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - David Savitzki
- Pediatric Neurology Unit, Galilee Medical Center, Nahariya, Israel
| | - Galit Tal
- Metabolic Unit, Rambam Health Care Campus, Rappaport School of Medicine, Haifa, Israel
| | - Hanna Mandel
- Metabolic Unit, Rambam Health Care Campus, Rappaport School of Medicine, Haifa, Israel.
| | - Hiroyuki Sugimoto
- Department of Biochemistry, Dokkyo Medical University School of Medicine, Mibu, Tochigi, Japan.
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15
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Ethanolamine and Phosphatidylethanolamine: Partners in Health and Disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:4829180. [PMID: 28785375 PMCID: PMC5529665 DOI: 10.1155/2017/4829180] [Citation(s) in RCA: 193] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 06/01/2017] [Indexed: 12/18/2022]
Abstract
Phosphatidylethanolamine (PE) is the second most abundant phospholipid in mammalian cells. PE comprises about 15–25% of the total lipid in mammalian cells; it is enriched in the inner leaflet of membranes, and it is especially abundant in the inner mitochondrial membrane. PE has quite remarkable activities: it is a lipid chaperone that assists in the folding of certain membrane proteins, it is required for the activity of several of the respiratory complexes, and it plays a key role in the initiation of autophagy. In this review, we focus on PE's roles in lipid-induced stress in the endoplasmic reticulum (ER), Parkinson's disease (PD), ferroptosis, and cancer.
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16
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Dymond MK, Gillams RJ, Parker DJ, Burrell J, Labrador A, Nylander T, Attard GS. Lipid Spontaneous Curvatures Estimated from Temperature-Dependent Changes in Inverse Hexagonal Phase Lattice Parameters: Effects of Metal Cations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10083-10092. [PMID: 27603198 DOI: 10.1021/acs.langmuir.6b03098] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recently we reported a method for estimating the spontaneous curvatures of lipids from temperature-dependent changes in the lattice parameter of inverse hexagonal liquid crystal phases of binary lipid mixtures. This method makes use of 1,2-dioleoyl-sn-glycerol-3-phosphoethanolamine (DOPE) as a host lipid, which preferentially forms an inverse hexagonal phase to which a guest lipid of unknown spontaneous curvature is added. The lattice parameters of these binary lipid mixtures are determined by small-angle X-ray diffraction at a range of temperatures and the spontaneous curvature of the guest lipid is determined from these data. Here we report the use of this method on a wide range of lipids under different ionic conditions. We demonstrate that our method provides spontaneous curvature values for DOPE, cholesterol, and monoolein that are within the range of values reported in the literature. Anionic lipids 1,2-dioleoyl-sn-glycerol-3-phosphatidic acid (DOPA) and 1,2-dioleoyl-sn-glycerol-3-phosphoserine (DOPS) were found to exhibit spontaneous curvatures that depend on the concentration of divalent cations present in the mixtures. We show that the range of curvatures estimated experimentally for DOPA and DOPS can be explained by a series of equilibria arising from lipid-cation exchange reactions. Our data indicate a universal relationship between the spontaneous curvature of a lipid and the extent to which it affects the lattice parameter of the hexagonal phase of DOPE when it is part of a binary mixture. This universal relationship affords a rapid way of estimating the spontaneous curvatures of lipids that are expensive, only available in small amounts, or are of limited chemical stability.
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Affiliation(s)
- Marcus K Dymond
- Division of Chemistry, School of Pharmacy and Biomolecular Sciences, University of Brighton , Brighton BN2 4GJ, U.K
| | - Richard J Gillams
- Chemistry, Faculty of Natural & Environmental Sciences, University of Southampton , Southampton SO17 1BJ, U.K
| | - Duncan J Parker
- Chemistry, Faculty of Natural & Environmental Sciences, University of Southampton , Southampton SO17 1BJ, U.K
| | - Jamie Burrell
- Chemistry, Faculty of Natural & Environmental Sciences, University of Southampton , Southampton SO17 1BJ, U.K
| | - Ana Labrador
- MAX IV Laboratory, Lund University , PO Box 118, SE-221 00 Lund, Sweden
| | - Tommy Nylander
- Physical Chemistry, Lund University , PO Box 124, SE-221 00 Lund, Sweden
| | - George S Attard
- Chemistry, Faculty of Natural & Environmental Sciences, University of Southampton , Southampton SO17 1BJ, U.K
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17
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Phosphatidic acid binding proteins display differential binding as a function of membrane curvature stress and chemical properties. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2709-2716. [PMID: 27480805 DOI: 10.1016/j.bbamem.2016.07.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/12/2016] [Accepted: 07/27/2016] [Indexed: 01/16/2023]
Abstract
Phosphatidic acid (PA) is a crucial membrane phospholipid involved in de novo lipid synthesis and numerous intracellular signaling cascades. The signaling function of PA is mediated by peripheral membrane proteins that specifically recognize PA. While numerous PA-binding proteins are known, much less is known about what drives specificity of PA-protein binding. Previously, we have described the ionization properties of PA, summarized in the electrostatic-hydrogen bond switch, as one aspect that drives the specific binding of PA by PA-binding proteins. Here we focus on membrane curvature stress induced by phosphatidylethanolamine and show that many PA-binding proteins display enhanced binding as a function of negative curvature stress. This result is corroborated by the observation that positive curvature stress, induced by lyso phosphatidylcholine, abolishes PA binding of target proteins. We show, for the first time, that a novel plant PA-binding protein, Arabidopsis Epsin-like Clathrin Adaptor 1 (ECA1) displays curvature-dependence in its binding to PA. Other established PA targets examined in this study include, the plant proteins TGD2, and PDK1, the yeast proteins Opi1 and Spo20, and, the mammalian protein Raf-1 kinase and the C2 domain of the mammalian phosphatidylserine binding protein Lact as control. Based on our observations, we propose that liposome binding assays are the preferred method to investigate lipid binding compared to the popular lipid overlay assays where membrane environment is lost. The use of complex lipid mixtures is important to elucidate further aspects of PA binding proteins.
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18
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Goñi FM. The basic structure and dynamics of cell membranes: an update of the Singer-Nicolson model. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1467-76. [PMID: 24440423 DOI: 10.1016/j.bbamem.2014.01.006] [Citation(s) in RCA: 210] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 12/30/2013] [Accepted: 01/08/2014] [Indexed: 01/03/2023]
Abstract
The fluid mosaic model of Singer and Nicolson (1972) is a commonly used representation of the cell membrane structure and dynamics. However a number of features, the result of four decades of research, must be incorporated to obtain a valid, contemporary version of the model. Among the novel aspects to be considered are: (i) the high density of proteins in the bilayer, that makes the bilayer a molecularly "crowded" space, with important physiological consequences; (ii) the proteins that bind the membranes on a temporary basis, thus establishing a continuum between the purely soluble proteins, never in contact with membranes, and those who cannot exist unless bilayer-bound; (iii) the progress in our knowledge of lipid phases, the putative presence of non-lamellar intermediates in membranes, and the role of membrane curvature and its relation to lipid geometry, (iv) the existence of lateral heterogeneity (domain formation) in cell membranes, including the transient microdomains known as rafts, and (v) the possibility of transient and localized transbilayer (flip-flop) lipid motion. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.
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Affiliation(s)
- Félix M Goñi
- Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain; Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain.
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19
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Schmidt NW, Mishra A, Wang J, DeGrado WF, Wong GCL. Influenza virus A M2 protein generates negative Gaussian membrane curvature necessary for budding and scission. J Am Chem Soc 2013; 135:13710-9. [PMID: 23962302 DOI: 10.1021/ja400146z] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The M2 protein is a multifunctional protein, which plays several roles in the replication cycle of the influenza A virus. Here we focus on its ability to promote budding of the mature virus from the cell surface. Using high-resolution small-angle X-ray scattering we show that M2 can restructure lipid membranes into bicontinuous cubic phases which are rich in negative Gaussian curvature (NGC). The active generation of negative Gaussian membrane curvature by M2 is essential to influenza virus budding. M2 has been observed to colocalize with the region of high NGC at the neck of a bud. The structural requirements for scission are even more stringent than those for budding, as the neck must be considerably smaller than the virus during 'pinch off'. Consistent with this, the amount of NGC in the induced cubic phases suggests that M2 proteins can generate high curvatures comparable to those on a neck with size 10× smaller than a spherical influenza virus. Similar experiments on variant proteins containing different M2 domains show that the cytoplasmic amphipathic helix is necessary and sufficient for NGC generation. Mutations to the helix which reduce its amphiphilicity and are known to diminish budding attenuated NGC generation. An M2 construct comprising the membrane interactive domains, the transmembrane helix and the cytoplasmic helix, displayed enhanced ability to generate NGC, suggesting that other domains cooperatively promote membrane curvature. These studies establish the importance of M2-induced NGC during budding and suggest that antagonizing this curvature is a viable anti-influenza strategy.
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Affiliation(s)
- Nathan W Schmidt
- Department of Bioengineering, University of California, Los Angeles , Los Angeles, California 90095, United States
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20
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Dymond MK, Hague CV, Postle AD, Attard GS. An in vivo ratio control mechanism for phospholipid homeostasis: evidence from lipidomic studies. J R Soc Interface 2012; 10:20120854. [PMID: 23256189 DOI: 10.1098/rsif.2012.0854] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
While it is widely accepted that the lipid composition of eukaryotic membranes is under homeostatic control, the mechanisms through which cells sense lipid composition are still the subject of debate. It has been postulated that membrane curvature elastic energy is the membrane property that is regulated by cells, and that lipid composition is maintained by a ratio control function derived from the concentrations of type II and type 0 lipids, weighted appropriately. We assess this proposal by seeking a signature of ratio control in quantified lipid composition data obtained by electrospray ionization mass spectrometry from over 40 independent asynchronous cell populations. Our approach revealed the existence of a universal 'pivot' lipid, which marks the boundary between type 0 lipids and type II lipids, and which is invariant between different cell types or cells grown under different conditions. The presence of such a pivot species is a distinctive signature of the operation in vivo, in human cell lines, of a control function that is consistent with the hypothesis that membrane elastic energy is homeostatically controlled.
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Affiliation(s)
- Marcus K Dymond
- Division of Chemistry, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton SO17 1BJ, UK.
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21
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Chan EYL, McQuibban GA. Phosphatidylserine decarboxylase 1 (Psd1) promotes mitochondrial fusion by regulating the biophysical properties of the mitochondrial membrane and alternative topogenesis of mitochondrial genome maintenance protein 1 (Mgm1). J Biol Chem 2012; 287:40131-9. [PMID: 23045528 DOI: 10.1074/jbc.m112.399428] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Phosphatidylethanolamine is proposed to regulate mitochondrial fusion, but its mechanism of action is unknown. RESULTS Decreasing phosphatidylethanolamine reduces the rate of lipid mixing and the biogenesis of Mgm1, a mitochondrial fusion protein. CONCLUSION Psd1 regulates the lipid and protein machineries of mitochondrial fusion. SIGNIFICANCE Understanding how lipid metabolism regulates mitochondrial dynamics will reveal its role in cellular functions such as apoptosis and autophagy. Non-bilayer-forming lipids such as cardiolipin, phosphatidic acid, and phosphatidylethanolamine (PE) are proposed to generate negative membrane curvature, promoting membrane fusion. However, the mechanism by which lipids regulate mitochondrial fusion remains poorly understood. Here, we show that mitochondrial-localized Psd1, the key yeast enzyme that synthesizes PE, is required for proper mitochondrial morphology and fusion. Yeast cells lacking Psd1 exhibit fragmented and aggregated mitochondria with impaired mitochondrial fusion during mating. More importantly, we demonstrate that a reduction in PE reduces the rate of lipid mixing during fusion of liposomes with lipid compositions reflecting the mitochondrial membrane. This suggests that the mitochondrial fusion defect in the Δpsd1 strain could be due to the altered biophysical properties of the mitochondrial membrane, resulting in reduced fusion kinetics. The Δpsd1 strain also has impaired mitochondrial activity such as oxidative phosphorylation and reduced mitochondrial ATP levels which are due to a reduction in mitochondrial PE. The loss of Psd1 also impairs the biogenesis of s-Mgm1, a protein essential for mitochondrial fusion, further exacerbating the mitochondrial fusion defect of the Δpsd1 strain. Increasing s-Mgm1 levels in Δpsd1 cells markedly reduced mitochondrial aggregation. Our results demonstrate that mitochondrial PE regulates mitochondrial fusion by regulating the biophysical properties of the mitochondrial membrane and by enhancing the biogenesis of s-Mgm1. While several proteins are required to orchestrate the intricate process of membrane fusion, we propose that specific phospholipids of the mitochondrial membrane promote fusion by enhancing lipid mixing kinetics and by regulating the action of profusion proteins.
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Affiliation(s)
- Eliana Y L Chan
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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22
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Leidy C, Ocampo J, Duelund L, Mouritsen OG, Jørgensen K, Peters GH. Membrane restructuring by phospholipase A2 is regulated by the presence of lipid domains. Biophys J 2011; 101:90-9. [PMID: 21723818 DOI: 10.1016/j.bpj.2011.02.062] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 02/22/2011] [Accepted: 02/24/2011] [Indexed: 12/13/2022] Open
Abstract
Secretory phospholipase A(2) (sPLA(2)) catalyzes the hydrolysis of glycerophospholipids. This enzyme is sensitive to membrane structure, and its activity has been shown to increase in the presence of liquid-crystalline/gel (L(α)/L(β)) lipid domains. In this work, we explore whether lipid domains can also direct the activity of the enzyme by inducing hydrolysis of certain lipid components due to preferential activity of the enzyme toward lipid domains susceptible to sPLA(2). Specifically, we show that the presence of L(α)/L(β) and L(α)/P(β') phase coexistence in a 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/1,2 distearoyl-sn-glycero-3-phosphocholine (DSPC) system results in the preferential hydrolysis of the shorter-chained lipid component in the mixture, leading to an enrichment in the longer-chained component. The restructuring process is monitored by atomic force microscopy on supported single and double bilayers formed by vesicle fusion. We observe that during preferential hydrolysis of the DMPC-rich L(α) regions, the L(β) and P(β') regions grow and reseal, maintaining membrane integrity. This result indicates that a sharp reorganization of the membrane structure can occur during sPLA(2) hydrolysis without necessarily destroying the membrane. We confirm by high-performance liquid chromatography the preferential hydrolysis of DMPC within the phase coexistence region of the DMPC/DSPC phase diagram, showing that this preferential hydrolysis is accentuated close to the solidus phase boundary. Differential scanning calorimetry results show that this preferential hydrolysis in the presence of lipid domains leads to a membrane system with a higher-temperature melting profile due to enrichment in DSPC. Together, these results show that the presence of lipid domains can induce specificity in the hydrolytic activity of the enzyme, resulting in marked differences in the physical properties of the membrane end-product.
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Affiliation(s)
- Chad Leidy
- Department of Physics, Universidad de los Andes, Bogotá, Colombia.
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23
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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: 189] [Impact Index Per Article: 14.5] [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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24
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Kudsiova L, Ho J, Fridrich B, Harvey R, Keppler M, Ng T, Hart SL, Tabor AB, Hailes HC, Lawrence* MJ. Lipid chain geometry of C14 glycerol-based lipids: effect on lipoplex structure and transfection. ACTA ACUST UNITED AC 2011; 7:422-36. [DOI: 10.1039/c0mb00149j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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25
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Perutková Š, Daniel M, Rappolt M, Pabst G, Dolinar G, Kralj-Iglič V, Iglič A. Elastic deformations in hexagonal phases studied by small-angle X-ray diffraction and simulations. Phys Chem Chem Phys 2010; 13:3100-7. [PMID: 21063616 DOI: 10.1039/c0cp01187h] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study we present experimental and theoretical results which concern the deviations from circularity of the pivotal plane in the inverse hexagonal phases (H(II)) of phospholipid self-assemblies. Due to packing constraints, the cross-section of the polar/apolar interface deviates from a circle, which we studied in minute detail by analysing small-angle X-ray diffraction data of dioleoyl-phosphatidylethanolamine (DOPE) and stearoyl-oleoyl-phosphatidylethanolamine (SOPE), respectively. On this structural basis, Monte Carlo (MC) simulated annealing variations of the free energy were carried out, both on the formation of the H(II)-phase and on the particular shape of the cross-section in the H(II)-phase. The equilibrium of the H(II)-phase pivotal plane contour and the corresponding values of the mean intrinsic curvature, H(m), and the hydrocarbon chain stiffness, τ, were determined from MC calculations. The results of these calculations were tested by solving the corresponding system of non-linear differential equations derived using variational calculus. Here our main aim is to predict the range of possible values of H(m) and τ. Comparing the measured structural data with predictions from MC calculations including lipid anisotropy, and accounting for the elastic deformations of the pivotal plane allowed us to determine a relationship between the bending deformation and stretching of hydrocarbon chains.
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Affiliation(s)
- Šárka Perutková
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia
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26
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Nicolosi D, Scalia M, Nicolosi VM, Pignatello R. Encapsulation in fusogenic liposomes broadens the spectrum of action of vancomycin against Gram-negative bacteria. Int J Antimicrob Agents 2010; 35:553-8. [DOI: 10.1016/j.ijantimicag.2010.01.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 11/26/2009] [Accepted: 01/09/2010] [Indexed: 10/19/2022]
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27
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Siegel DP. Fourth-order curvature energy model for the stability of bicontinuous inverted cubic phases in amphiphile-water systems. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8673-8683. [PMID: 20349969 DOI: 10.1021/la904838z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The bicontinuous inverted cubic (Q(II)) phases of amphiphiles in water have many practical applications. It is necessary to understand the stability of these phases as a function of composition and ambient conditions in order to make the best use of them. Moreover, many biomembrane lipids and some biomembrane lipid extracts form Q(II) phases. The stability of Q(II) phases in a given lipid composition is closely related to the susceptibility of that composition to membrane fusion: changes in composition that stabilize Q(II) phases usually increase the rate of membrane fusion. However, the factors determining Q(II) phase stability are not fully understood. Previously, an expression was derived for the curvature free energy of Q(II) phases with respect to that of the lamellar (L(alpha)) phase using a model for the curvature energy with terms up to fourth order in curvature as formulated by Mitov. Here this model is extended to account for the effects of water content on Q(II) phase stability. It is shown that the observed L(alpha)/Q(II) phase-transition temperature, transition enthalpy, and transition kinetics are all sensitive to water content. The same observables also become sensitive to small noncurvature energy contributions to the total free-energy difference between the Q(II) and L(alpha) phases, especially the unbinding energy in the L(alpha) phase. These predictions rationalize earlier observations of Q(II) phase formation in N-monomethylated dioleoylphosphatidylethanolamine that otherwise appear to be inconsistent. The model also provides a fundamental explanation of the hysteresis typically observed in transitions between the L(alpha) and Q(II) phases. It is an accurate model of Q(II) phase stability when the ratio of the volume fraction of the lipid in the Q(II) phase unit cell is < or = 0.5.
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Affiliation(s)
- David P Siegel
- Givaudan Inc., 1199 Edison Drive, Cincinnati, Ohio 45216, USA.
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28
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Mosior M, Epand RM. Role of the Membrane in the Modulation of the Activity of Protein Kinase C. J Liposome Res 2008. [DOI: 10.3109/08982109909044490] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
The Gaussian curvature elastic energy contribution to the energy of membrane fusion intermediates has usually been neglected because the Gaussian curvature elastic modulus, kappa, was unknown. It is now possible to measure kappa for phospholipids that form bicontinuous inverted cubic (Q(II)) phases. Here, it is shown that one can estimate kappa for lipids that do not form Q(II) phases by studying the phase behavior of lipid mixtures. The method is used to estimate kappa for several lipid compositions in excess water. The values of kappa are used to compute the curvature elastic energies of stalks and catenoidal fusion pores according to recent models. The Gaussian curvature elastic contribution is positive and similar in magnitude to the bending energy contribution: it increases the total curvature energy of all the fusion intermediates by 100 units of k(B)T or more. It is important to note that this contribution makes the predicted intermediate energies compatible with observed lipid phase behavior in excess water. An order-of-magnitude fusion rate equation is used to estimate whether the predicted stalk energies are consistent with the observed rates of stalk-mediated processes in pure lipid systems. The current theory predicts a stalk energy that is slightly too large, by approximately 30 k(B)T, to rationalize the observed rates of stalk-mediated processes in phosphatidylethanolamine or N-monomethylated dioleoylphosphatidylethanolamine systems. Despite this discrepancy, the results show that models of fusion intermediate energy are accurate enough to make semiquantitative predictions about how proteins mediate biomembrane fusion. The same rate model shows that for proteins to drive biomembrane fusion at observed rates, they have to perform mediating functions corresponding to a reduction in the energy of a purely lipidic stalk by several tens of k(B)T. By binding particular peptide sequences to the monolayer surface, proteins could lower fusion intermediate energies by altering the elastic constants of the patches of lipid monolayer that form the stalk. Here, it is shown that if peptide binding changes kappa or some other combinations of local elastic constants by only tens of percents, the stalk energy and the energy of catenoidal fusion pores would decrease by tens of k(B)T relative to the pure lipid value. This is comparable to the required mediating effect. The curvature energies of stalks and catenoidal fusion pores have almost the same dependence on monolayer elastic constants as the curvature energies of the rhombohedral and Q(II) phases; respectively. The effects of isolated fusion-relevant peptides on the energies of these intermediates can be determined by studying the effects of the peptides on the stability of rhombohedral and Q(II) phases.
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MacLachlan I. Lipid-Mediated in vivo Delivery of Small Interfering RNAs. THERAPEUTIC OLIGONUCLEOTIDES 2008. [DOI: 10.1039/9781847558275-00241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Ian MacLachlan
- Protiva Biotherapeutics Inc. 100-3480 Gilmore Way Burnaby BC Canada V5G 4Y1
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31
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Influence of the lamellar phase unbinding energy on the relative stability of lamellar and inverted cubic phases. Biophys J 2008; 94:3987-95. [PMID: 18234828 DOI: 10.1529/biophysj.107.118034] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Based on curvature energy considerations, nonbilayer phase-forming phospholipids in excess water should form stable bicontinuous inverted cubic (Q(II)) phases at temperatures between the lamellar (L(alpha)) and inverted hexagonal (H(II)) phase regions. However, the phosphatidylethanolamines (PEs), which are a common class of biomembrane phospholipids, typically display direct L(alpha)/H(II) phase transitions and may form intermediate Q(II) phases only after the temperature is cycled repeatedly across the L(alpha)/H(II) phase transition temperature, T(H), or when the H(II) phases are cooled from T > T(H). This raises the question of whether models of inverted phase stability, which are based on curvature energy alone, accurately predict the relative free energy of these phases. Here we demonstrate the important role of a noncurvature energy contribution, the unbinding energy of the L(alpha) phase bilayers, g(u), that serves to stabilize the L(alpha) phase relative to the nonlamellar phases. The planar L(alpha) phase bilayers must separate for a Q(II) phase to form and it turns out that the work of their unbinding can be larger than the curvature energy reduction on formation of Q(II) phase from L(alpha) at temperatures near the L(alpha)/Q(II) transition temperature (T(Q)). Using g(u) and elastic constant values typical of unsaturated PEs, we show that g(u) is sufficient to make T(Q) > T(H) for the latter lipids. Such systems would display direct L(alpha) --> H(II) transitions, and a Q(II) phase might only form as a metastable phase upon cooling of the H(II) phase. The g(u) values for methylated PEs and PE/phosphatidylcholine mixtures are significantly smaller than those for PEs and increase T(Q) by only a few degrees, consistent with observations of these systems. This influence of g(u) also rationalizes the effect of some aqueous solutes to increase the rate of Q(II) formation during temperature cycling of lipid dispersions. Finally, the results are relevant to protocols for determining the Gaussian curvature modulus, which substantially affects the energy of intermediates in membrane fusion and fission. Recently, two such methods were proposed based on measuring T(Q) and on measuring Q(II) phase unit cell dimensions, respectively. In view of the effect of g(u) on T(Q) that we describe here, the latter method, which does not depend on the value of g(u), is preferable.
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32
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Specific lipids supply critical negative spontaneous curvature--an essential component of native Ca2+-triggered membrane fusion. Biophys J 2008; 94:3976-86. [PMID: 18227127 DOI: 10.1529/biophysj.107.123984] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Ca(2+)-triggered merger of two apposed membranes is the defining step of regulated exocytosis. CHOL is required at critical levels in secretory vesicle membranes to enable efficient, native membrane fusion: CHOL-sphingomyelin enriched microdomains organize the site and regulate fusion efficiency, and CHOL directly supports the capacity for membrane merger by virtue of its negative spontaneous curvature. Specific, structurally dissimilar lipids substitute for CHOL in supporting the ability of vesicles to fuse: diacylglycerol, alphaT, and phosphatidylethanolamine support triggered fusion in CHOL-depleted vesicles, and this correlates quantitatively with the amount of curvature each imparts to the membrane. Lipids of lesser negative curvature than cholesterol do not support fusion. The fundamental mechanism of regulated bilayer merger requires not only a defined amount of membrane-negative curvature, but this curvature must be provided by molecules having a specific, critical spontaneous curvature. Such a local lipid composition is energetically favorable, ensuring the necessary "spontaneous" lipid rearrangements that must occur during native membrane fusion-Ca(2+)-triggered fusion pore formation and expansion. Thus, different fusion sites or vesicle types can use specific alternate lipidic components, or combinations thereof, to facilitate and modulate the fusion pore.
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33
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Lam AD, Tryoen-Toth P, Tsai B, Vitale N, Stuenkel EL. SNARE-catalyzed fusion events are regulated by Syntaxin1A-lipid interactions. Mol Biol Cell 2007; 19:485-97. [PMID: 18003982 DOI: 10.1091/mbc.e07-02-0148] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Membrane fusion is a process that intimately involves both proteins and lipids. Although the SNARE proteins, which ultimately overcome the energy barrier for fusion, have been extensively studied, regulation of the energy barrier itself, determined by specific membrane lipids, has been largely overlooked. Our findings reveal a novel function for SNARE proteins in reducing the energy barrier for fusion, by directly binding and sequestering fusogenic lipids to sites of fusion. We demonstrate a specific interaction between Syntaxin1A and the fusogenic lipid phosphatidic acid, in addition to multiple polyphosphoinositide lipids, and define a polybasic juxtamembrane region within Syntaxin1A as its lipid-binding domain. In PC-12 cells, Syntaxin1A mutations that progressively reduced lipid binding resulted in a progressive reduction in evoked secretion. Moreover, amperometric analysis of fusion events driven by a lipid-binding-deficient Syntaxin1A mutant (5RK/A) demonstrated alterations in fusion pore dynamics, suggestive of an energetic defect in secretion. Overexpression of the phosphatidic acid-generating enzyme, phospholipase D1, completely rescued the secretory defect seen with the 5RK/A mutant. Moreover, knockdown of phospholipase D1 activity drastically reduced control secretion, while leaving 5RK/A-mediated secretion relatively unaffected. Altogether, these data suggest that Syntaxin1A-lipid interactions are a critical determinant of the energetics of SNARE-catalyzed fusion events.
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Affiliation(s)
- Alice D Lam
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.
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34
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Epand RM. Membrane lipid polymorphism: relationship to bilayer properties and protein function. Methods Mol Biol 2007; 400:15-26. [PMID: 17951724 DOI: 10.1007/978-1-59745-519-0_2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Bilayers are the most familiar arrangement of phospholipids. However, even as bilayers, phospholipids can arrange themselves in a variety of morphologies from essentially flat structures found in large liposomes or when adhered to a flat solid support, to the curved structures found in small liposomes or as bicontinuous cubic phases. Phospholipids can also arrange themselves as curved monolayers, such as in the hexagonal phase, and they can even form spherical or ellipsoid-shaped micelles. A number of factors will determine the final morphology of a lipid aggregate including the structure of the lipid, the nature of the lipid headgroup and its degree of hydration, and the temperature. In addition to being interesting in its own right, the property of lipid polymorphism can be applied to understand how fundamental intrinsic curvature properties of a membrane alter the physical properties of a membrane bilayer. This, in turn, will affect the functional characteristics of membrane proteins, with several possible mechanisms explaining the coupling of membrane properties with protein function.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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35
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Kozlov MM. Determination of lipid spontaneous curvature from X-ray examinations of inverted hexagonal phases. Methods Mol Biol 2007; 400:355-366. [PMID: 17951746 DOI: 10.1007/978-1-59745-519-0_24] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Structure of a lipid monolayer can be characterized by its spontaneous shape corresponding to a stress-free state. In the chapter, the rigorous description of monolayer shape in terms of curvature of a Gibbs dividing surface is reviewed, and the notions of the neutral and pivotal surfaces are discussed. Further, the effective and exact method of finding the position of the pivotal surface and the corresponding monolayer spontaneous curvature of cylindrically curved monolayers based on the results of the X-ray scattering experiments are presented. Briefly, some limitations of this method are discussed.
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Affiliation(s)
- Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Israel
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36
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Hohner A, Bayer J, Rädler JO. Wormlike lipid/DNA micelles in a non-polar solvent. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 21:41-8. [PMID: 17041743 DOI: 10.1140/epje/i2006-10043-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Accepted: 09/20/2006] [Indexed: 05/12/2023]
Abstract
The phase behavior of DOPE/DOTAP-DNA complexes in phase-separated oil(dodecane)/water mixtures was explored using Small Angle X-Ray Scattering (SAXS) and Fluorescence Correlation Spectroscopy (FCS). Inverse micelles of DNA with cationic-lipid coating were found in the oil phase. Varying the ratio between cationic and neutral lipids a transition from wormlike to spherical structures is observed for both long ( approximately 75000bp) and short (30-1246bp) DNA. In contrast to lipid/DNA complexes in the water phase, there is no indication of condensed liquid-crystalline structures in the non-polar phase. In fact, FCS measurements on short DNA oligomers complexed with cationic lipid in alkane give clear evidence for monomeric inverse micelles of DNA. Dilution series revealed a critical lower concentration of lipids and DNA for observing lipid/DNA micelles.
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Affiliation(s)
- A Hohner
- Geschwister-Scholl-Platz 1, Ludwig-Maximilians-Universität, D-80539, München, Germany
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37
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Sternin E, Zaraiskaya T, Razavi R, Epand RM. Changes in molecular order across the lamellar-to-inverted hexagonal phase transition depend on the position of the double-bond in mono-unsaturated phospholipid dispersions. Chem Phys Lipids 2006; 140:98-108. [PMID: 16574088 DOI: 10.1016/j.chemphyslip.2006.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2005] [Revised: 02/10/2006] [Accepted: 02/17/2006] [Indexed: 10/24/2022]
Abstract
A series of mono-unsaturated phosphatidylethanolamine (PE) model membranes is studied using deuterium nuclear magnetic resonance (NMR) and differential scanning calorimetry. As the position of the double bond is systematically changed, the internal conformational motions are monitored through the bilayer-to-inverted-hexagonal phase transition. The order parameter profiles extracted from the NMR spectra report on the conformational order of the lipid and on the way this order is changed by structural reorganizations of the membrane. The calculation of a ratio of renormalized order parameter profiles is presented here as an attempt to distill the essential features of these changes into dimensionless descriptions of "shape" functions. This variation of the extent of molecular disorder along the long molecular axis of the phospholipids appears to be a recurring motif, modulated by temperature, structural rearrangement, and chemical composition of the membrane. The reported experimentally measured changes in the shape of the order parameter profile can be compared to those obtained during molecular dynamics simulation studies.
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Affiliation(s)
- Edward Sternin
- Department of Physics, Brock University, 500 Glenridge Avenue, St. Catharines, Ont., Canada.
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38
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Ahyayauch H, Larijani B, Alonso A, Goñi FM. Detergent solubilization of phosphatidylcholine bilayers in the fluid state: influence of the acyl chain structure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:190-6. [PMID: 16579963 DOI: 10.1016/j.bbamem.2006.01.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Revised: 12/22/2005] [Accepted: 01/20/2006] [Indexed: 10/25/2022]
Abstract
Seventeen different, chemically defined phosphatidylcholines, dispersed in aqueous medium in the form of large unilamellar vesicles, have been tested for solubilization by the non-ionic detergent Triton X-100. The temperatures (either 20 degrees C or 45 degrees C) were such that the bilayers were always in the liquid-disordered state. For each case, the solubilization parameters, Don (total detergent: lipid mole ratio producing the onset of solubilization) and D50 (total detergent: lipid mole ratio producing 50% solubilization), were determined under equilibrium conditions. Both parameters varied generally in parallel. When double bonds were introduced to the acyl chains, other factors remaining constant, solubilization became more difficult, i.e., more detergent was required. Cis-unsaturated phospholipids required more detergent than the corresponding trans-isomers. Increasing chain length in saturated phospholipids between C12 and C16 decreased moderately the detergent/lipid ratios causing solubilization. Acyl and alkyl phospholipids were equally susceptible to Triton X-100 solubilization. Lipid chain order, as measured by DPH fluorescence polarization, seemed to facilitate solubilization, perhaps because more ordered bilayers have a smaller capacity to accommodate detergent monomers without breaking down into lipid-detergent mixed micelles.
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Affiliation(s)
- Hasna Ahyayauch
- Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain, and Cell Biophysics Lab Cancer Research UK, London Research Institute, UK
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39
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Heyes J, Palmer L, Bremner K, MacLachlan I. Cationic lipid saturation influences intracellular delivery of encapsulated nucleic acids. J Control Release 2005; 107:276-87. [PMID: 16054724 DOI: 10.1016/j.jconrel.2005.06.014] [Citation(s) in RCA: 371] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Revised: 06/14/2005] [Accepted: 06/15/2005] [Indexed: 11/17/2022]
Abstract
An analogous series of cationic lipids (1,2-distearyloxy-N,N-dimethyl-3-aminopropane (DSDMA), 1,2-dioleyloxy-N,N-dimethyl-3-aminopropane (DODMA), 1,2-dilinoleyloxy-N,N-dimethyl-3-aminopropane (DLinDMA) and 1,2-dilinolenyloxy-N,N-dimethyl-3-aminopropane (DLenDMA)) possessing 0, 1, 2 or 3 double bonds per alkyl chain respectively, was synthesized to determine the correlation between lipid saturation, fusogenicity and efficiency of intracellular nucleic acid delivery. 31P-NMR analysis suggests that as saturation increases, from 2 to 0 double bonds, lamellar (L(alpha)) to reversed hexagonal (H(II)) phase transition temperature increases, indicating decreasing fusogenicity. This trend is largely reflected by the efficiency of gene silencing observed in vitro when the lipids are formulated as Stable Nucleic Acid Lipid Particles (SNALPs) encapsulating small inhibitory RNA (siRNA). Uptake experiments suggest that despite their lower gene silencing efficiency, the less fusogenic particles are more readily internalized by cells. Microscopic visualization of fluorescently labelled siRNA uptake was supported by quantitative data acquired using radiolabelled preparations. Since electrostatic binding is a precursor to uptake, the pKa of each cationic lipid was determined. The results support a transfection model in which endosomal release, mediated by fusion with the endosomal membrane, results in cytoplasmic translocation of the nucleic acid payload.
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Affiliation(s)
- James Heyes
- Protiva Biotherapeutics Inc., 100-3480 Gilmore Way, Burnaby, B.C., Canada V5G-4Y1
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40
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Churchward MA, Rogasevskaia T, Höfgen J, Bau J, Coorssen JR. Cholesterol facilitates the native mechanism of Ca2+-triggered membrane fusion. J Cell Sci 2005; 118:4833-48. [PMID: 16219690 DOI: 10.1242/jcs.02601] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The process of regulated exocytosis is defined by the Ca2+-triggered fusion of two apposed membranes, enabling the release of vesicular contents. This fusion step involves a number of energetically complex steps and requires both protein and lipid membrane components. The role of cholesterol has been investigated using isolated release-ready native cortical secretory vesicles to analyze the Ca2+-triggered fusion step of exocytosis. Cholesterol is a major component of vesicle membranes and we show here that selective removal from membranes, selective sequestering within membranes, or enzymatic modification causes a significant inhibition of the extent, Ca2+ sensitivity and kinetics of fusion. Depending upon the amount incorporated, addition of exogenous cholesterol to cholesterol-depleted membranes consistently recovers the extent, but not the Ca2+ sensitivity or kinetics of fusion. Membrane components of comparable negative curvature selectively recover the ability to fuse, but are unable to recover the kinetics and Ca2+ sensitivity of vesicle fusion. This indicates at least two specific positive roles for cholesterol in the process of membrane fusion: as a local membrane organizer contributing to the efficiency of fusion, and, by virtue of its intrinsic negative curvature, as a specific molecule working in concert with protein factors to facilitate the minimal molecular machinery for fast Ca2+-triggered fusion.
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Affiliation(s)
- Matthew A Churchward
- Department of Physiology and Biophysics, Hotchkiss Brain Institute, University of Calgary, Health Sciences Centre, Faculty of Medicine, Calgary, Alberta, T2N 4N1, Canada
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41
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Epand RM, Epand RF, Hughes DW, Sayer BG, Borochov N, Bach D, Wachtel E. Phosphatidylcholine structure determines cholesterol solubility and lipid polymorphism. Chem Phys Lipids 2005; 135:39-53. [PMID: 15854624 DOI: 10.1016/j.chemphyslip.2005.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Revised: 12/14/2004] [Accepted: 01/31/2005] [Indexed: 11/18/2022]
Abstract
In the present work, we demonstrate that phosphatidylcholine with (16:1)9 acyl chains undergoes polymorphic rearrangements in mixtures with 0.6-0.8 mol fraction cholesterol. Studies were performed using differential scanning calorimetry, X-ray diffraction, cryo-electron microscopy, 31P NMR static powder patterns and 13C MAS/NMR. Mixtures of phosphatidylcholine with (16:1)9 acyl chains and 0.6 mol fraction cholesterol, after being heated to 100 degrees C, can form an ordered array with periodicity 14 nm which may be indicative of a cubic phase. Our results indicate that the formation of highly curved bilayer structures, such as those required for membrane fusion, can occur in mixtures of cholesterol with certain phosphatidylcholines that do not form non-lamellar structures in the absence of cholesterol. We also determine the polymorphic behavior of mixtures of symmetric phosphatidylcholines with cholesterol. Species of phosphatidylcholine with (20:1)11, (22:1)13 or (24:1)15 acyl chains in mixtures with 0.6-0.8 mol fraction cholesterol undergo a transition to the hexagonal phase at temperatures 70-80 degrees C. This is not the case for phosphatidylcholine with (18:1)6 acyl chains which remains in the lamellar phase up to 100 degrees C when mixed with as much as 0.8 mol fraction cholesterol. Thus, the polymorphic behavior of mixtures of phosphatidylcholine and cholesterol is not uncommon and is dependent on the intrinsic curvature of the phospholipid. Crystals of cholesterol can be detected in mixtures of all of these phosphatidylcholines at sufficiently high cholesterol mole fraction. What is unusual about the formation of these crystals in several cases is that cholesterol crystals are present in the monohydrate form in preference to the anhydrous form. Furthermore, after heating to 100 degrees C and recooling, the cholesterol crystals are again observed to be in the monohydrate form, although pure cholesterol crystals require many hours to rehydrate after being heated to 100 degrees C. Both the nature of the acyl chain as well as the mole fraction cholesterol determine whether cholesterol crystals in mixtures with the phospholipids will be in the monohydrate or in the anhydrous form.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main Street West, Hamilton, Ont., Canada L8N 3Z5.
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42
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Fanani ML, Topham MK, Walsh JP, Epand RM. Lipid modulation of the activity of diacylglycerol kinase alpha- and zeta-isoforms: activation by phosphatidylethanolamine and cholesterol. Biochemistry 2005; 43:14767-77. [PMID: 15544347 DOI: 10.1021/bi049145z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Diacylglycerol kinase (DGK) isoforms alpha and zeta were extracted from transfected cells that overexpressed these enzymes. We determined the lipid dependence of the binding of these isoforms to liposomes. The modulation by lipid of the rate of phosphorylation of diacylglycerol by these enzymes was also measured. Incorporation of phosphatidylethanolamine into the liposomes resulted in an increased partitioning of both isoforms of DGK to the membrane as well as an increased catalytic rate. We demonstrate that the increased catalytic rate is a consequence of both increased portioning of the enzyme to the membrane and increased catalytic activity of the membrane-bound form. DGKalpha, a calcium-dependent isoform, can be activated in a calcium-independent fashion in the presence of phosphatidylethanolamine. Similar effects are observed with cholesterol. In contrast, sphingomyelin inhibits the activity of both isoforms of DGK. Our results demonstrate that the translocation to membranes and activity of DGKalpha and DGKzeta are modulated by the composition and properties of the membrane. The enzymes are activated by the presence of lipids that promote the formation of inverted phases. However, the promotion of negative curvature is not the sole factor contributing to the lipid effects on enzyme binding and activity. A truncated form of DGKalphalacking both the E-F hand and the recoverin homology domain is constitutively active and is not further activated by any of the lipids tested or by calcium. However, a truncated form lacking only the recoverin homology domain is partially activated by either calcium or certain lipids.
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Affiliation(s)
- Maria Laura Fanani
- Department of Biochemistry and Biomedical Sciences, McMaster University Health Science Center, Hamilton, Ontario L8N 3Z5, Canada
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43
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Abstract
Gramicidin is an antibiotic peptide that can be incorporated into the monolayers of cell membranes. Dimerization through hydrogen bonding between gramicidin monomers in opposing leaflets of the membrane results in the formation of an iontophoretic channel. Surrounding phospholipids influence the gating properties of this channel. Conversely, gramicidin incorporation has been shown to affect the structure of spontaneously formed lipid assemblies. Using small-angle x-ray diffraction and model systems composed of phospholipids and gramicidin, the effects produced by gramicidin on lipid layers were measured. These measurements explore how peptides are able to modulate the spontaneous curvature properties of phospholipid assemblies. The reverse hexagonal, H(II), phase formed by dioleoylphosphatidylethanolamine (DOPE) monolayers decreased in lattice dimension with increasing incorporation of gramicidin. This indicated that gramicidin itself was adding negative curvature to the lipid layers. In this system, gramicidin was measured to have an apparent intrinsic radius of curvature, R0pgram, of -7.1 A. The addition of up to 4 mol% gramicidin in DOPE did not result in the monolayers becoming stiffer, as measured by the monolayer bending moduli. Dioleoylphosphatidylcholine (DOPC) alone forms the lamellar (L(alpha)) phase when hydrated, but undergoes a transition into the reverse hexagonal (H(II)) phase when mixed with gramicidin. The lattice dimension decreases systematically with increased gramicidin content. Again, this indicated that gramicidin was adding negative curvature to the lipid monolayers but the mixture behaved structurally much less consistently than DOPE/gramicidin. Only at 12 mol% gramicidin in dioleoylphosphatidylcholine could an apparent radius of intrinsic curvature of gramicidin (R0pgram) be estimated as -7.4 A. This mixture formed monolayers that were very resistant to bending, with a measured bending modulus of 115 kT.
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Affiliation(s)
- J A Szule
- Biological Sciences, Brock University, St. Catharines, Ontario, Canada, L2S 3A1
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44
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Drobnies AE, Davies SMA, Kraayenhof R, Epand RF, Epand RM, Cornell RB. CTP:phosphocholine cytidylyltransferase and protein kinase C recognize different physical features of membranes: differential responses to an oxidized phosphatidylcholine. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1564:82-90. [PMID: 12100999 DOI: 10.1016/s0005-2736(02)00404-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Protein kinase C (PKC) and CTP:phosphocholine cytidylyltransferase (CT) are two examples of enzymes that are regulated by reversible binding to membranes, and this binding is influenced by membrane physical properties. CT activation by oxidized phosphatidylcholines was recently demonstrated and was linked to the acyl chain disordering effect of the oxidized species (Biochemistry 38, 15606). In this paper, we compare the responses of PKC and CT to an oxidized PC, and investigate the physical properties of lipid bilayers that modulate the activity of these enzymes. We show that 1-palmitoyl, 2-(11,15 dihydroxy) eicosatrienoyl PC (diOH-PAPC) caused less of an increase in the temperature of the lamellar to hexagonal II transition (T(H)) of an unsaturated PE, compared to its parent, PAPC. Using a polarity-sensitive interfacial probe, we also found evidence to suggest that this oxidized PC increases interfacial packing pressure. We found that whereas diOH-PAPC activates CT, it inhibits PKC relative to the parent PAPC. The activities of both CT and PKC are known to increase in the presence of non-lamellar forming lipids. The greater activating effect of diOH-PAPC compared with PAPC, is consistent with a stimulation of the activity of CT by negative curvature strain. However, this is not the case with PKC, for which we suggest that surface packing pressure is of prime importance.
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Affiliation(s)
- Adrienne E Drobnies
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
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45
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Davies SM, Epand RM, Kraayenhof R, Cornell RB. Regulation of CTP: phosphocholine cytidylyltransferase activity by the physical properties of lipid membranes: an important role for stored curvature strain energy. Biochemistry 2001; 40:10522-31. [PMID: 11523994 DOI: 10.1021/bi010904c] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CTP:Phosphocholine cytidylyltransferase (CT) catalyzes the key step in phosphatidylcholine (PC) synthesis. CT is activated by binding to certain lipid membranes. The membrane binding affinity of CT can vary from micromolar to millimolar K(d), depending on the lipid composition of the target membrane. Class II CT activators like diacylglycerols and unsaturated phosphatidylethanolamines (PE) favor inverted lipid phase formation. The mechanism(s) governing CT's association with class II lipid membranes and subsequent activation are relatively unknown. We measured CT activation by vesicles composed of PC and one of three unsaturated PEs, dioleoylglycerol (DOG), or cholesterol. For each lipid system, we estimated the stored curvature strain energy of the monolayer when confined to a relatively flat bilayer. CT binding and activation correlate very well with the curvature strain energy of several chemically distinct class II lipid systems, with the exception of those containing cholesterol, in which CT activation was less than the increase in curvature strain. CT activation by membranes containing DOG was reversed by inclusion of specific lysolipids, which reduce curvature strain energy. LysoPC, which has a larger positive curvature than lysoPE, produced greater inhibition of CT activation. Stored curvature strain energy is thus an important determinant of CT activation. Membrane interfacial polarity was investigated using a membrane-anchored fluorescent probe. Decreases in quenching of this interfacial probe by doxyl-PCs in class II membranes suggest the probe adopts a more superficial membrane location. This may reflect an increased surface hydrophobicity of class II lipid membranes, implying a role for surface dehydration in CT's interactions with membranes containing class II lipids. Cholesterol, a poor activator of CT, did not affect the positioning of the polarity-sensitive probe, suggesting that one reason for its ineffectiveness is an inability to enhance surface hydrophobicity.
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Affiliation(s)
- S M Davies
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
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Epand RM, Epand RF, Decicco A, Schwarz D. Curvature properties of novel forms of phosphatidylcholine with branched acyl chains. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:2909-15. [PMID: 10806388 DOI: 10.1046/j.1432-1327.2000.01304.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We studied the properties of a series of phosphatidylcholine molecules with branched acyl chains. These lipids have previously been shown to have marked stimulatory effects on the side-chain cleavage activity of cytochrome P450SCC (CYP11A1), an enzyme of the inner mitochondrial membrane. The synthetic lipids used were diacyl phosphatidylcholines with the decanoyl, dodecanoyl or tetradecanoyl chain having a hexyl, octyl or decyl straight chain aliphatic branch at the 2-position. All three lipids lowered the bilayer to hexagonal phase transition temperature of dielaidoyl phosphatidylethanolamine, the lipids with longer acyl chains being more effective in this regard. As pure lipids all of the forms were found by X-ray diffraction to be predominantly in the hexagonal phase (HII) over the entire temperature range of 7-75 degrees C. The properties of the HII phase were unusual with regard to the small size of the lattice spacings and the small temperature dependence of the spacings. We used tetradecane to relieve hydrocarbon packing constraints to determine the intrinsic radius of curvature of the lipid monolayer. The elastic bending modulus was measured in the presence of tetradecane by introducing an osmotic gradient across the hexagonal phase cylinders with aqueous solutions of poly(ethylene glycol). The elastic bending modulus was found to be higher than that observed with other lipids and to increase with temperature. Both the small intrinsic radius of curvature and the high elastic bending modulus indicate that the presence of these lipids in bilayer membranes will impose a high degree of negative curvature strain.
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Affiliation(s)
- R M Epand
- Department of Biochemistry, McMaster University Health Sciences Center, Hamilton, Canada.
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van der Wel PC, Pott T, Morein S, Greathouse DV, Koeppe RE, Killian JA. Tryptophan-anchored transmembrane peptides promote formation of nonlamellar phases in phosphatidylethanolamine model membranes in a mismatch-dependent manner. Biochemistry 2000; 39:3124-33. [PMID: 10715134 DOI: 10.1021/bi9922594] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To better understand the mutual interactions between lipids and membrane-spanning peptides, we investigated the effects of tryptophan-anchored hydrophobic peptides of various lengths on the phase behavior of 1,2-dielaidoylphosphatidylethanolamine (DEPE) dispersions, using (31)P nuclear magnetic resonance and small-angle X-ray diffraction. Designed alpha-helical transmembrane peptides (WALPn peptides, with n being the total number of amino acids) with a hydrophobic sequence of leucine and alanine of varying length, bordered at both ends by two tryptophan membrane anchors, were used as model peptides and were effective at low concentrations in DEPE. Incorporation of 2 mol % of relatively short peptides (WALP14-17) lowered the inverted hexagonal phase transition temperature (T(H)) of DEPE, with an efficiency that seemed to be independent of the extent of hydrophobic mismatch. However, the tube diameter of the H(II) phase induced by the peptides was clearly dependent on mismatch and decreased with shorter peptide length. Longer peptides (WALP19-27) induced a cubic phase, both below and above T(H). Incorporation of WALP27, which is significantly longer than the DEPE bilayer thickness, did not stabilize the bilayer. The longest peptide used, WALP31, hardly affected the lipid's phase behavior, and appeared not to incorporate into the bilayer. The consequences of hydrophobic mismatch between peptides and lipids are therefore more dramatic with shorter peptides. The data allow us to suggest a detailed molecular model of the mechanism by which these transmembrane peptides can affect lipid phase behavior.
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Affiliation(s)
- P C van der Wel
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
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Abstract
Non-lamellar-forming lipids play an important role in determining the physical properties of membranes. They affect the activity of membrane proteins and peptides. In addition, peptides which lyse membranes as well as those which promote membrane fusion facilitate the formation of non-lamellar phases, either micelles, cubic or hexagonal phases. The relationship of these diverse effects on membrane curvature is discussed in relation to the function of certain peptides and proteins. Specific examples of ionophoric peptides, cytotoxic peptides and viral fusion peptides are given. In addition, we compare the modulation of the rate of photoisomerisation of an integral membrane protein, rhodopsin, by non-lamellar-forming lipids with the effects of these lipids on an amphitropic protein, protein kinase C. Among these diverse systems it is frequently observed that the modulation of biological activity can be described in terms of the effect of the peptide or protein on the relative stability of lamellar and non-lamellar structures.
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Affiliation(s)
- R M Epand
- Department of Biochemistry, McMaster University Health Sciences Centre, Hamilton, Ont. L8N 3Z5, Canada.
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Giorgione JR, Kraayenhof R, Epand RM. Interfacial membrane properties modulate protein kinase C activation: role of the position of acyl chain unsaturation. Biochemistry 1998; 37:10956-60. [PMID: 9692988 DOI: 10.1021/bi980185a] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We studied the effects of the addition of a series of 1, 2-dioctadecenoyl-sn-glycerol-3-phosphoethanolamines to vesicles composed of 1-palmitoyl-2-oleoylphosphatidylserine and 1-palmitoyl-2-oleoylphosphatidylcholine on the activity and membrane binding of protein kinase C (PKC). The three phosphatidylethanolamines (PEs) were dipetroselinoyl-PE, dioleoyl-PE, and divaccenoyl-PE, which have double bonds in positions 6, 9, and 11, respectively. These lipids represent a group of structurally homologous compounds whose physical properties have been compared. We also used a fluorescent probe, 4-[(n-dodecylthio)methyl]-7-(N, N-dimethylamino)coumarin to measure the relative interfacial polarities of LUVs containing each of the three PEs. We find dipetroselinoyl-PE allows the least access of the fluorescent probe to the membrane. This is also the lipid that shows the lowest activation of PKC. The activity of PKC was found to correlate best with the interfacial properties of the three PEs rather than with the curvature energy of the membrane. The results show the sensitivity of the activity of PKC to small changes in lipid structure.
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Affiliation(s)
- J R Giorgione
- Department of Biochemistry, McMaster University Health Sciences Centre, Hamilton, Ontario, Canada
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Goldberg EM, Zidovetzki R. Synergistic effects of diacylglycerols and fatty acids on membrane structure and protein kinase C activity. Biochemistry 1998; 37:5623-32. [PMID: 9548948 DOI: 10.1021/bi9719354] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The synergistic effects of diacylglycerol (DAG) and fatty acid (FA) in activating protein kinase C have been investigated by correlating their individual and combined effects on enzymatic activity and on membrane structure in phosphatidylcholine/phosphatidylserine (4:1) lipid mixtures using a combination of specific enzymatic assays and 31P and 2H NMR. Addition of DAGs and unsaturated FAs to the bilayers synergistically increased the tendency of the lipids to form nonbilayer phases with a concomitant increase in PKC activity until a maximum was achieved. Further increases in the DAG/FA concentration led to the formation of the nonbilayer lipid phases under the conditions of the PKC activity assays and correlated with decreased activity. The nonbilayer lipid phases still supported PKC activity, although with less than 50% efficiency as compared with the bilayer lipids. Long-chain saturated FA increased DAG-induced PKC activity by causing a lateral phase separation of gel (Lbeta) and liquid-crystalline (Lalpha) domains. Due to the preferential partitioning of DAGs into liquid-crystalline domains, the local DAG concentration increased in these domains, leading to an increase in PKC activity. Because a wide range of lipophilic compounds is capable of altering curvature stress, and therefore the tendency for nonbilayer phase formation in cellular membranes, these compounds would be expected to modulate PKC activity and the activities of a number of other membrane-associated enzymes that are sensitive to biophysical properties of lipid membranes.
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Affiliation(s)
- E M Goldberg
- Department of Biology, University of California, Riverside 92521, USA
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