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Zimmerberg J, Soubias O, Pastor RW. Special issue for Klaus Gawrisch. Biophys J 2023; 122:E1-E8. [PMID: 36921597 PMCID: PMC10111273 DOI: 10.1016/j.bpj.2023.02.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 02/15/2023] [Accepted: 02/15/2023] [Indexed: 03/17/2023] Open
Affiliation(s)
- Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Olivier Soubias
- Macromolecular NMR Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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2
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Pyne S, Pyne P, Mitra RK. Addition of cholesterol alters the hydration at the surface of model lipids: a spectroscopic investigation. Phys Chem Chem Phys 2022; 24:20381-20389. [PMID: 35983752 DOI: 10.1039/d2cp01905a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cholesterol is known to modify the phase behavior of model lipid membranes as it makes phospholipid bilayers more structured. Simulation results have shown that the addition of cholesterol allows more bulk-like water to protrude into phospholipid interfaces. However, such claims have not yet been verified experimentally. We have investigated the alteration in the hydrogen bond network structure of water at the surface of two model phospholipids DOPC and DOPG as cholesterol is added into these using ATR-FTIR spectroscopy in the FIR-THz region. Our measurements and analysis led us to probe the collective H-bond network explicitly at the lipid surface. A detailed principal component analysis of the measured data concludes that the water-water H-bond vibration dynamics gets slower at the lipid surface as compared to bulk water, the effect being more prominent in the case of the charged phospholipid, DOPG. However, as cholesterol is added and more bulk-like water protrudes into the liposome interface, the H-bond vibration gets weaker and correspondingly the dynamics gets accelerated.
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Affiliation(s)
- Sumana Pyne
- Department of Chemical Biological and Macromolecular Sciences, S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India.
| | - Partha Pyne
- Department of Chemical Biological and Macromolecular Sciences, S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India.
| | - Rajib Kumar Mitra
- Department of Chemical Biological and Macromolecular Sciences, S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India.
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3
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de Santis A, Scoppola E, Ottaviani MF, Koutsioubas A, Barnsley LC, Paduano L, D’Errico G, Russo Krauss I. Order vs. Disorder: Cholesterol and Omega-3 Phospholipids Determine Biomembrane Organization. Int J Mol Sci 2022; 23:ijms23105322. [PMID: 35628128 PMCID: PMC9140907 DOI: 10.3390/ijms23105322] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/06/2022] [Accepted: 05/07/2022] [Indexed: 02/06/2023] Open
Abstract
Lipid structural diversity strongly affects biomembrane chemico-physical and structural properties in addition to membrane-associated events. At high concentrations, cholesterol increases membrane order and rigidity, while polyunsaturated lipids are reported to increase disorder and flexibility. How these different tendencies balance in composite bilayers is still controversial. In this study, electron paramagnetic resonance spectroscopy, small angle neutron scattering, and neutron reflectivity were used to investigate the structural properties of cholesterol-containing lipid bilayers in the fluid state with increasing amounts of polyunsaturated omega-3 lipids. Either the hybrid 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine or the symmetric 1,2-docosahexaenoyl-sn-glycero-3-phosphocholine were added to the mixture of the naturally abundant 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and cholesterol. Our results indicate that the hybrid and the symmetric omega-3 phospholipids affect the microscopic organization of lipid bilayers differently. Cholesterol does not segregate from polyunsaturated phospholipids and, through interactions with them, is able to suppress the formation of non-lamellar structures induced by the symmetric polyunsaturated lipid. However, this order/disorder balance leads to a bilayer whose structural organization cannot be ascribed to either a liquid ordered or to a canonical liquid disordered phase, in that it displays a very loose packing of the intermediate segments of lipid chains.
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Affiliation(s)
- Augusta de Santis
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy; (A.d.S.); (L.P.)
- CSGI (Consorzio per lo Sviluppo dei Sistemi a Grande Interfase), I-50019 Florence, Italy
| | - Ernesto Scoppola
- Max Planck Institut für Kolloid und Grenzflächenforschung, 14476 Potsdam, Germany;
| | | | - Alexandros Koutsioubas
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), 85748 Garching, Germany; (A.K.); (L.C.B.)
| | - Lester C. Barnsley
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), 85748 Garching, Germany; (A.K.); (L.C.B.)
- Australian Synchrotron, ANSTO, Clayton 3168, Australia
| | - Luigi Paduano
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy; (A.d.S.); (L.P.)
- CSGI (Consorzio per lo Sviluppo dei Sistemi a Grande Interfase), I-50019 Florence, Italy
| | - Gerardino D’Errico
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy; (A.d.S.); (L.P.)
- CSGI (Consorzio per lo Sviluppo dei Sistemi a Grande Interfase), I-50019 Florence, Italy
- Correspondence: (G.D.); (I.R.K.)
| | - Irene Russo Krauss
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy; (A.d.S.); (L.P.)
- CSGI (Consorzio per lo Sviluppo dei Sistemi a Grande Interfase), I-50019 Florence, Italy
- Correspondence: (G.D.); (I.R.K.)
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4
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Capability of Polyunsaturated Phosphatidylcholine for Non-raft Domain Formation in Cholesterol-containing Lipid Bilayers. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2022. [DOI: 10.1380/ejssnt.2022-015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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5
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Non-raft submicron domain formation in cholesterol-containing lipid bilayers induced by polyunsaturated phosphatidylethanolamine. Colloids Surf B Biointerfaces 2021; 210:112235. [PMID: 34891064 DOI: 10.1016/j.colsurfb.2021.112235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/08/2021] [Accepted: 11/16/2021] [Indexed: 12/13/2022]
Abstract
Domain formation in "HLC" ternary lipid bilayers, comprising a high transition temperature (High-Tm) lipid, a Low-Tm lipid, and cholesterol (Chol), has been extensively studied as raft-resembling systems. Recently, we reported the formation of submicron domains in an "LLC" lipid bilayer, encompassing Low-Tm phosphatidylethanolamine (PE), Low-Tm phosphatidylcholine (PC), and Chol. We hypothesized that the formation of this unique domain is driven by polyunsaturated PE. In this study, we explored the effects of the degree of PE unsaturation and the double bond distribution at the sn-position on the mechanism of formation and the composition of submicron domains. Supported lipid bilayers (SLBs), comprising PE with various degrees of unsaturation, monounsaturated PC (POPC), and Chol, were investigated using fluorescence microscopy, atomic force microscopy, and the force-distance curve measurement. The area fraction of submicron domains in PE+POPC+Chol-SLB increased with the PE concentration and degree of unsaturation of the PE acyl chain. The results indicated that the submicron domains were enriched with polyunsaturated PE and were in the liquid-disordered-like state, whereas their surrounding regions were in the liquid-ordered-like state. Segregation of polyunsaturated PE from the Chol-containing region generated submicron domains in the LLC lipid bilayer. We propose a mechanism for the formation of these submicron domains based on molecular interactions involving the hydrophobic and hydrophilic parts of the bilayer membrane.
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6
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Javanainen M, Martinez-Seara H. Rapid diffusion of cholesterol along polyunsaturated membranes via deep dives. Phys Chem Chem Phys 2019; 21:11660-11669. [PMID: 31119241 DOI: 10.1039/c9cp02022e] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cholesterol regulates the function of membrane proteins either via direct or membrane-mediated effects. Therefore, its ready availability is crucial for many protein-governed cellular processes. Recent studies suggest that cholesterol can partition to the core of polyunsaturated membranes, where cholesterol binding sites of many membrane proteins are also located. This core region is characterized by a lower viscosity. Therefore, we hypothesized that cholesterol partitioning into the membrane interior increases the rate of its diffusion in polyunsaturated membrane environments. We studied the behavior of cholesterol in membranes with increasing level of lipid chain unsaturation using a combination of atomistic and coarse-grained molecular dynamics simulations. Our simulations suggest a strong correlation between entropy-driven enhanced cholesterol partitioning to the membrane core and its faster lateral diffusion, which indicates that the less viscous membrane core indeed provides an efficient means for cholesterol movement in polyunsaturated membrane environments.
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Affiliation(s)
- Matti Javanainen
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 542/2, CZ-166 10 Prague 6, Czech Republic.
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7
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Leng X, Kinnun JJ, Cavazos AT, Canner SW, Shaikh SR, Feller SE, Wassall SR. All n-3 PUFA are not the same: MD simulations reveal differences in membrane organization for EPA, DHA and DPA. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2018; 1860:1125-1134. [PMID: 29305832 PMCID: PMC5963985 DOI: 10.1016/j.bbamem.2018.01.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 12/19/2017] [Accepted: 01/01/2018] [Indexed: 01/01/2023]
Abstract
Eicosapentaenoic (EPA, 20:5), docosahexaenoic (DHA, 22:6) and docosapentaenoic (DPA, 22:5) acids are omega-3 polyunsaturated fatty acids (n-3 PUFA) obtained from dietary consumption of fish oils that potentially alleviate the symptoms of a range of chronic diseases. We focus here on the plasma membrane as a site of action and investigate how they affect molecular organization when taken up into a phospholipid. All atom MD simulations were performed to compare 1-stearoyl-2-eicosapentaenoylphosphatylcholine (EPA-PC, 18:0-20:5PC), 1-stearoyl-2-docosahexaenoylphosphatylcholine (DHA-PC, 18:0-22:6PC), 1-stearoyl-2-docosapentaenoylphosphatylcholine (DPA-PC, 18:0-22:5PC) and, as a monounsaturated control, 1-stearoyl-2-oleoylphosphatidylcholine (OA-PC, 18:0-18:1PC) bilayers. They were run in the absence and presence of 20mol% cholesterol. Multiple double bonds confer high disorder on all three n-3 PUFA. The different number of double bonds and chain length for each n-3 PUFA moderates the reduction in membrane order exerted (compared to OA-PC, S¯CD=0.152). EPA-PC (S¯CD=0.131) is most disordered, while DPA-PC (S¯CD=0.140) is least disordered. DHA-PC (S¯CD=0.139) is, within uncertainty, the same as DPA-PC. Following the addition of cholesterol, order in EPA-PC (S¯CD=0.169), DHA-PC (S¯CD=0.178) and DPA-PC (S¯CD=0.182) is increased less than in OA-PC (S¯CD=0.214). The high disorder of n-3 PUFA is responsible, preventing the n-3 PUFA-containing phospholipids from packing as close to the rigid sterol as the monounsaturated control. Our findings establish that EPA, DHA and DPA are not equivalent in their interactions within membranes, which possibly contributes to differences in clinical efficacy.
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Affiliation(s)
- Xiaoling Leng
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States
| | - Jacob J Kinnun
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States
| | - Andres T Cavazos
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States
| | - Samuel W Canner
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States; Department of Computer Science and Information Science, IUPUI, Indianapolis, IN 46202-5132, United States
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Scott E Feller
- Department of Chemistry, Wabash College, Crawfordsville, IN 47933, United States
| | - Stephen R Wassall
- Department of Physics, IUPUI, Indianapolis, IN 46202-3273, United States.
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8
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Membrane-Active Properties of an Amphitropic Peptide from the CyaA Toxin Translocation Region. Toxins (Basel) 2017; 9:toxins9110369. [PMID: 29135925 PMCID: PMC5705984 DOI: 10.3390/toxins9110369] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 12/28/2022] Open
Abstract
The adenylate cyclase toxin CyaA is involved in the early stages of infection by Bordetella pertussis, the causative agent of whooping cough. CyaA intoxicates target cells by a direct translocation of its catalytic domain (AC) across the plasma membrane and produces supraphysiological levels of cAMP, leading to cell death. The molecular process of AC translocation remains largely unknown, however. We have previously shown that deletion of residues 375–485 of CyaA selectively abrogates AC translocation into eukaryotic cells. We further identified within this “translocation region” (TR), P454 (residues 454–484), a peptide that exhibits membrane-active properties, i.e., is able to bind and permeabilize lipid vesicles. Here, we analyze various sequences from CyaA predicted to be amphipatic and show that although several of these peptides can bind membranes and adopt a helical conformation, only the P454 peptide is able to permeabilize membranes. We further characterize the contributions of the two arginine residues of P454 to membrane partitioning and permeabilization by analyzing the peptide variants in which these residues are substituted by different amino acids (e.g., A, K, Q, and E). Our data shows that both arginine residues significantly contribute, although diversely, to the membrane-active properties of P454, i.e., interactions with both neutral and anionic lipids, helix formation in membranes, and disruption of lipid bilayer integrity. These results are discussed in the context of the translocation process of the full-length CyaA toxin.
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9
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Characterization of lipid rafts in human platelets using nuclear magnetic resonance: A pilot study. Biochem Biophys Rep 2017; 10:132-136. [PMID: 28955740 PMCID: PMC5614646 DOI: 10.1016/j.bbrep.2017.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/28/2017] [Accepted: 03/15/2017] [Indexed: 11/23/2022] Open
Abstract
Lipid microdomains (‘lipid rafts’) are plasma membrane subregions, enriched in cholesterol and glycosphingolipids, which participate dynamically in cell signaling and molecular trafficking operations. One strategy for the study of the physicochemical properties of lipid rafts in model membrane systems has been the use of nuclear magnetic resonance (NMR), but until now this spectroscopic method has not been considered a clinically relevant tool. We performed a proof-of-concept study to test the feasibility of using NMR to study lipid rafts in human tissues. Platelets were selected as a cost-effective and minimally invasive model system in which lipid rafts have previously been studied using other approaches. Platelets were isolated from plasma of medication-free adult research participants (n=13) and lysed with homogenization and sonication. Lipid-enriched fractions were obtained using a discontinuous sucrose gradient. Association of lipid fractions with GM1 ganglioside was tested using HRP-conjugated cholera toxin B subunit dot blot assays. 1H high resolution magic-angle spinning nuclear magnetic resonance (HRMAS NMR) spectra obtained with single-pulse Bloch decay experiments yielded spectral linewidths and intensities as a function of temperature. Rates of lipid lateral diffusion that reported on raft size were measured with a two-dimensional stimulated echo longitudinal encode-decode NMR experiment. We found that lipid fractions at 10–35% sucrose density associated with GM1 ganglioside, a marker for lipid rafts. NMR spectra of the membrane phospholipids featured a prominent ‘centerband’ peak associated with the hydrocarbon chain methylene resonance at 1.3 ppm; the linewidth (full width at half-maximum intensity) of this ‘centerband’ peak, together with the ratio of intensities between the centerband and ‘spinning sideband’ peaks, agreed well with values reported previously for lipid rafts in model membranes. Decreasing temperature produced decreases in the 1.3 ppm peak intensity and a discontinuity at ~18 °C, for which the simplest explanation is a phase transition from Ld to Lo phases indicative of raft formation. Rates of lateral diffusion of the acyl chain lipid signal at 1.3 ppm, a quantitative measure of microdomain size, were consistent with lipid molecules organized in rafts. These results show that HRMAS NMR can characterize lipid microdomains in human platelets, a methodological advance that could be extended to other tissues in which membrane biochemistry may have physiological and pathophysiological relevance. Lipid raft properties have been studied mainly in model membranes or cell cultures. We report a novel 1H NMR approach to lipid raft characterization in human platelets. We find spectroscopy, diffusion, and phase transitions consistent with lipid rafts. NMR plus bioassays may be used to study raft-mediated cell function in human tissues.
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10
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Ermilova I, Lyubartsev AP. Extension of the Slipids Force Field to Polyunsaturated Lipids. J Phys Chem B 2016; 120:12826-12842. [DOI: 10.1021/acs.jpcb.6b05422] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Inna Ermilova
- Department of Materials and
Environmental Chemistry, Stockholm University, SE 106 91 Stockholm, Sweden
| | - Alexander P. Lyubartsev
- Department of Materials and
Environmental Chemistry, Stockholm University, SE 106 91 Stockholm, Sweden
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11
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Marquardt D, Heberle FA, Greathouse DV, Koeppe RE, Standaert RF, Van Oosten BJ, Harroun TA, Kinnun JJ, Williams JA, Wassall SR, Katsaras J. Lipid bilayer thickness determines cholesterol's location in model membranes. SOFT MATTER 2016; 12:9417-9428. [PMID: 27801465 DOI: 10.1039/c6sm01777k] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Cholesterol is an essential biomolecule of animal cell membranes, and an important precursor for the biosynthesis of certain hormones and vitamins. It is also thought to play a key role in cell signaling processes associated with functional plasma membrane microdomains (domains enriched in cholesterol), commonly referred to as rafts. In all of these diverse biological phenomena, the transverse location of cholesterol in the membrane is almost certainly an important structural feature. Using a combination of neutron scattering and solid-state 2H NMR, we have determined the location and orientation of cholesterol in phosphatidylcholine (PC) model membranes having fatty acids of different lengths and degrees of unsaturation. The data establish that cholesterol reorients rapidly about the bilayer normal in all the membranes studied, but is tilted and forced to span the bilayer midplane in the very thin bilayers. The possibility that cholesterol lies flat in the middle of bilayers, including those made from PC lipids containing polyunsaturated fatty acids (PUFAs), is ruled out. These results support the notion that hydrophobic thickness is the primary determinant of cholesterol's location in membranes.
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Affiliation(s)
- Drew Marquardt
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada and Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Frederick A Heberle
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee 37996, USA and Joint Institute for Biological Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | - Denise V Greathouse
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Roger E Koeppe
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Robert F Standaert
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Department of Biochemistry and Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Brad J Van Oosten
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada
| | - Thad A Harroun
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada
| | - Jacob J Kinnun
- Department of Physics, Indiana University - Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
| | - Justin A Williams
- Department of Physics, Indiana University - Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
| | - Stephen R Wassall
- Department of Physics, Indiana University - Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
| | - John Katsaras
- Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada and The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee 37996, USA and Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA. and Shull Wollan Center-a Joint Institute for Neutron Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
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12
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Marquardt D, Kučerka N, Wassall SR, Harroun TA, Katsaras J. Cholesterol's location in lipid bilayers. Chem Phys Lipids 2016; 199:17-25. [DOI: 10.1016/j.chemphyslip.2016.04.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 04/01/2016] [Accepted: 04/02/2016] [Indexed: 02/07/2023]
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13
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Achilles A, Bärenwald R, Lechner BD, Werner S, Ebert H, Tschierske C, Blume A, Bacia K, Saalwächter K. Self-Assembly of X-Shaped Bolapolyphiles in Lipid Membranes: Solid-State NMR Investigations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:673-682. [PMID: 26735449 DOI: 10.1021/acs.langmuir.5b03712] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A novel class of rigid-rod bolapolyphilic molecules with three philicities (rigid aromatic core, mobile aliphatic side chains, polar end groups) has recently been demonstrated to incorporate into and span lipid membranes, and to exhibit a rich variety of self-organization modes, including macroscopically ordered snowflake structures with 6-fold symmetry. In order to support a structural model and to better understand the self-organization on a molecular scale, we here report on proton and carbon-13 high-resolution magic-angle spinning solid-state NMR investigations of two different bolapolyphiles (BPs) in model membranes of two different phospholipids (DPPC, DOPC). We elucidate the changes in molecular dynamics associated with three new phase transitions detected by calorimetry in composite membranes of different composition, namely, a change in π-π-packing, the melting of lipid tails associated with the superstructure, and the dissolution and onset of free rotation of the BPs. We derive dynamic order parameters associated with different H-H and C-H bond directions of the BPs, demonstrating that the aromatic cores are well packed below the final phase transition, showing only 180° flips of the phenyl ring, and that they perform free rotations with additional oscillations of the long axis when dissolved in the fluid membrane. Our data suggests that BPs not only form ordered superstructures, but also rather homogeneously dispersed π-packed filaments within the lipid gel phase, thus reducing the corrugation of large vesicles.
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Affiliation(s)
- Anja Achilles
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
| | - Ruth Bärenwald
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
| | - Bob-Dan Lechner
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
| | - Stefan Werner
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
| | - Helgard Ebert
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
| | - Carsten Tschierske
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
| | - Alfred Blume
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
| | - Kirsten Bacia
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
| | - Kay Saalwächter
- Institut für Physik - NMR, ‡Institut für Chemie - Physikalische Chemie, §ZIK HALOmem, and ∥Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , D-06120 Halle, Germany
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14
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n-3 polyunsaturated fatty acids suppress CD4(+) T cell proliferation by altering phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2] organization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:85-96. [PMID: 26476105 DOI: 10.1016/j.bbamem.2015.10.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/12/2015] [Accepted: 10/13/2015] [Indexed: 02/07/2023]
Abstract
The mechanisms by which n-3 polyunsaturated fatty acids (n-3 PUFA), abundant in fish oil, exert their anti-inflammatory effects have not been rigorously defined. We have previously demonstrated that n-3 PUFA decrease the amount of phosphatidylinositol-(4,5)-bisphosphate, [PI(4,5)P2], in CD4(+) T cells, leading to suppressed actin remodeling upon activation. Since discrete pools of PI(4,5)P2 exist in the plasma membrane, we determined whether n-3 PUFA modulate spatial organization of PI(4,5)P2 relative to raft and non-raft domains. We used Förster resonance energy transfer (FRET) to demonstrate that lipid raft mesodomains in the plasma membrane of CD4(+) T cells enriched in n-3 PUFA display increased co-clustering of Lck(N10) and LAT(ΔCP), markers of lipid rafts. CD4(+) T cells enriched in n-3 PUFA also exhibited a depleted plasma membrane non-raft PI(4,5)P2 pool as detected by decreased co-clustering of Src(N15), a non-raft marker, and PH(PLC-δ), a PI(4,5)P2 reporter. Incubation with exogenous PI(4,5)P2 rescued the effects on the non-raft PI(4,5)P2 pool, and reversed the suppression of T cell proliferation in CD4(+) T cells enriched with n-3 PUFA. Furthermore, CD4(+) T cells isolated from mice fed a 4% docosahexaenoic acid (DHA)-enriched diet exhibited a decrease in the non-raft pool of PI(4,5)P2, and exogenous PI(4,5)P2 reversed the suppression of T cell proliferation. Finally, these effects were not due to changes to post-translational lipidation, since n-3 PUFA did not alter the palmitoylation status of signaling proteins. These data demonstrate that n-3 PUFA suppress T cell proliferation by altering plasma membrane topography and the spatial organization of PI(4,5)P2.
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Leng X, Kinnun JJ, Marquardt D, Ghefli M, Kučerka N, Katsaras J, Atkinson J, Harroun TA, Feller SE, Wassall SR. α-Tocopherol Is Well Designed to Protect Polyunsaturated Phospholipids: MD Simulations. Biophys J 2015; 109:1608-18. [PMID: 26488652 PMCID: PMC4624157 DOI: 10.1016/j.bpj.2015.08.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 08/20/2015] [Accepted: 08/24/2015] [Indexed: 01/08/2023] Open
Abstract
The presumptive function for alpha-tocopherol (αtoc) in membranes is to protect polyunsaturated lipids against oxidation. Although the chemistry of the process is well established, the role played by molecular structure that we address here with atomistic molecular-dynamics simulations remains controversial. The simulations were run in the constant particle NPT ensemble on hydrated lipid bilayers composed of SDPC (1-stearoyl-2-docosahexaenoylphosphatidylcholine, 18:0-22:6PC) and SOPC (1-stearoyl-2-oleoylphosphatidylcholine, 18:0-18:1PC) in the presence of 20 mol % αtoc at 37°C. SDPC with SA (stearic acid) for the sn-1 chain and DHA (docosahexaenoic acid) for the sn-2 chain is representative of polyunsaturated phospholipids, while SOPC with OA (oleic acid) substituted for the sn-2 chain serves as a monounsaturated control. Solid-state (2)H nuclear magnetic resonance and neutron diffraction experiments provide validation. The simulations demonstrate that high disorder enhances the probability that DHA chains at the sn-2 position in SDPC rise up to the bilayer surface, whereby they encounter the chromanol group on αtoc molecules. This behavior is reflected in the van der Waals energy of interaction between αtoc and acyl chains, and illustrated by density maps of distribution for acyl chains around αtoc molecules that were constructed. An ability to more easily penetrate deep into the bilayer is another attribute conferred upon the chromanol group in αtoc by the high disorder possessed by DHA. By examining the trajectory of single molecules, we found that αtoc flip-flops across the SDPC bilayer on a submicrosecond timescale that is an order-of-magnitude greater than in SOPC. Our results reveal mechanisms by which the sacrificial hydroxyl group on the chromanol group can trap lipid peroxyl radicals within the interior and near the surface of a polyunsaturated membrane. At the same time, water-soluble reducing agents that regenerate αtoc can access the chromanol group when it locates at the surface.
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Affiliation(s)
- Xiaoling Leng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
| | - Drew Marquardt
- Department of Physics, Brock University, St. Catharines, Ontario, Canada; Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Mikel Ghefli
- Department of Chemistry, Brock University, St. Catharines, Ontario, Canada
| | - Norbert Kučerka
- Canadian Neutron Beam Centre, National Research Council, Chalk River, Ontario, Canada; Faculty of Pharmacy, Comenius University, Bratislava, Slovakia
| | - John Katsaras
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Joint Institute for Neutron Sciences, Oak Ridge, Tennessee; Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee
| | - Jeffrey Atkinson
- Department of Chemistry, Brock University, St. Catharines, Ontario, Canada
| | - Thad A Harroun
- Department of Physics, Brock University, St. Catharines, Ontario, Canada
| | - Scott E Feller
- Department of Chemistry, Wabash College, Crawfordsville, Indiana
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana.
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16
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Fiorini R, Pagliarani A, Nesci S, Trombetti F, Pirini M, Fabbri M, Ventrella V. Lipid unsaturation per se does not explain the physical state of mitochondrial membranes in Mytilus galloprovincialis. Comp Biochem Physiol B Biochem Mol Biol 2015; 191:66-75. [PMID: 26456349 DOI: 10.1016/j.cbpb.2015.09.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 09/24/2015] [Accepted: 09/25/2015] [Indexed: 01/28/2023]
Abstract
Through a multiple approach, the present study on the mitochondrial membranes from mussel gills and swine heart combines some biochemical information on fatty acid composition, sterol pattern, and temperature dependence of the F1FO-ATPase activity (EC 3.6.3.14.) with fluorescence data on mitochondrial membranes and on liposomes obtained from lipid extracts of mitochondria. The physical state of mussel gills and swine heart was investigated by Laurdan steady state fluorescence. Quite surprisingly, the similar temperature dependence of the F1FO complex, illustrated as Arrhenius plot which in both mitochondria exhibits the same discontinuity at approximately 21°C and overlapping activation energies above and below the discontinuity, is apparently compatible with a different composition and physical state of mitochondrial membranes. Accordingly, mussel membranes contain highly unsaturated fatty acids, abundant sterols, including phytosterols, while mammalian membranes only contain cholesterol and in prevalence shorter and less unsaturated fatty acids, leading to a lower membrane unsaturation with respect to mussel mitochondria. As suggested by fluorescence data, the likely formation of peculiar microdomains interacting with the membrane-bound enzyme complex in mussel mitochondria could produce an environment which somehow approaches the physical state of mammalian mitochondrial membranes. Thus, as an adaptive strategy, the interaction between sterols, highly unsaturated phospholipids and proteins in mussel gill mitochondria could allow the F1FO-ATPase activity to maintain the same activation energy as the mammalian enzyme.
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Affiliation(s)
- Rosamaria Fiorini
- Department of Life and Environmental Sciences, Marche Polytechnic University, Montedago, 60131 Ancona, Italy.
| | - Alessandra Pagliarani
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano Emilia, Bologna, Italy
| | - Salvatore Nesci
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano Emilia, Bologna, Italy
| | - Fabiana Trombetti
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano Emilia, Bologna, Italy
| | - Maurizio Pirini
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano Emilia, Bologna, Italy
| | - Micaela Fabbri
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano Emilia, Bologna, Italy
| | - Vittoria Ventrella
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano Emilia, Bologna, Italy
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17
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Cheng CY, Olijve LLC, Kausik R, Han S. Cholesterol enhances surface water diffusion of phospholipid bilayers. J Chem Phys 2015; 141:22D513. [PMID: 25494784 DOI: 10.1063/1.4897539] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Elucidating the physical effect of cholesterol (Chol) on biological membranes is necessary towards rationalizing their structural and functional role in cell membranes. One of the debated questions is the role of hydration water in Chol-embedding lipid membranes, for which only little direct experimental data are available. Here, we study the hydration dynamics in a series of Chol-rich and depleted bilayer systems using an approach termed (1)H Overhauser dynamic nuclear polarization (ODNP) NMR relaxometry that enables the sensitive and selective determination of water diffusion within 5-10 Å of a nitroxide-based spin label, positioned off the surface of the polar headgroups or within the nonpolar core of lipid membranes. The Chol-rich membrane systems were prepared from mixtures of Chol, dipalmitoyl phosphatidylcholine and/or dioctadecyl phosphatidylcholine lipid that are known to form liquid-ordered, raft-like, domains. Our data reveal that the translational diffusion of local water on the surface and within the hydrocarbon volume of the bilayer is significantly altered, but in opposite directions: accelerated on the membrane surface and dramatically slowed in the bilayer interior with increasing Chol content. Electron paramagnetic resonance (EPR) lineshape analysis shows looser packing of lipid headgroups and concurrently tighter packing in the bilayer core with increasing Chol content, with the effects peaking at lipid compositions reported to form lipid rafts. The complementary capability of ODNP and EPR to site-specifically probe the hydration dynamics and lipid ordering in lipid membrane systems extends the current understanding of how Chol may regulate biological processes. One possible role of Chol is the facilitation of interactions between biological constituents and the lipid membrane through the weakening or disruption of strong hydrogen-bond networks of the surface hydration layers that otherwise exert stronger repulsive forces, as reflected in faster surface water diffusivity. Another is the concurrent tightening of lipid packing that reduces passive, possibly unwanted, diffusion of ions and water across the bilayer.
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Affiliation(s)
- Chi-Yuan Cheng
- Department of Chemistry and Biochemistry and Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA
| | - Luuk L C Olijve
- Laboratory of Macromolecular and Organic Chemistry and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Ravinath Kausik
- Department of Chemistry and Biochemistry and Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA
| | - Songi Han
- Department of Chemistry and Biochemistry and Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA
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18
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Foglia F, Lawrence M, Barlow D. Studies of model biological and bio-mimetic membrane structure: Reflectivity vs diffraction, a critical comparison. Curr Opin Colloid Interface Sci 2015. [DOI: 10.1016/j.cocis.2015.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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19
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Synthesis of cholesterol analogs having varying length alkyl side chains including cholesterol-23, 23, 24, 24, 25, 26, 26, 26, 27, 27, 27-d11 as probes of cholesterol's functions and properties. Chem Phys Lipids 2013; 175-176:99-104. [DOI: 10.1016/j.chemphyslip.2013.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 08/08/2013] [Accepted: 08/12/2013] [Indexed: 01/23/2023]
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20
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Darwish TA, Luks E, Moraes G, Yepuri NR, Holden PJ, James M. Synthesis of deuterated [D32 ]oleic acid and its phospholipid derivative [D64 ]dioleoyl-sn-glycero-3-phosphocholine. J Labelled Comp Radiopharm 2013; 56:520-9. [PMID: 24285531 DOI: 10.1002/jlcr.3088] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 06/12/2013] [Accepted: 06/12/2013] [Indexed: 11/07/2022]
Abstract
Oleic acid and its phospholipid derivatives are fundamental to the structure and function of cellular membranes. As a result, there has been increasing interest in the availability of their deuterated forms for many nuclear magnetic resonance, infrared, mass spectroscopy and neutron scattering studies. Here, we present for the first time a straightforward, large-scale (gram quantities) synthesis of highly deuterated [D32 ]oleic acid by using multiple, yet simple and high yielding reactions. The precursors for the synthesis of [D32 ]oleic acid are [D14 ]azelaic acid and [D17 ]nonanoic acid, which were obtained by complete deuteration (>98% D) of their (1) H forms by using metal catalysed hydrothermal H/D exchange reactions. The oleic acid was produced with ca. 94% D isotopic purity and with no contamination by the trans-isomer (elaidic acid). The subsequent synthesis of [D64 ]dioleoyl-sn-glycero-3-phosphocholine from [D32 ]oleic acid is also described.
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Affiliation(s)
- Tamim A Darwish
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001 Kirrawee, DC NSW, 2232, Australia
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21
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Raza Shaikh S, Brown DA. Models of plasma membrane organization can be applied to mitochondrial membranes to target human health and disease with polyunsaturated fatty acids. Prostaglandins Leukot Essent Fatty Acids 2013; 88:21-5. [PMID: 22464052 PMCID: PMC3391319 DOI: 10.1016/j.plefa.2012.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 03/08/2012] [Accepted: 03/12/2012] [Indexed: 12/14/2022]
Abstract
Bioactive n-3 polyunsaturated fatty acids (PUFA), abundant in fish oil, have potential for treating symptoms associated with inflammatory and metabolic disorders; therefore, it is essential to determine their fundamental molecular mechanisms. Recently, several labs have demonstrated the n-3 PUFA docosahexaenoic acid (DHA) exerts anti-inflammatory effects by targeting the molecular organization of plasma membrane microdomains. Here we briefly review the evidence that DHA reorganizes the spatial distribution of microdomains in several model systems. We then emphasize how models on DHA and plasma membrane microdomains can be applied to mitochondrial membranes. We discuss the role of DHA acyl chains in regulating mitochondrial lipid-protein clustering, and how these changes alter several aspects of mitochondrial function. In particular, we summarize effects of DHA on mitochondrial respiration, electron leak, permeability transition, and mitochondrial calcium handling. Finally, we conclude by postulating future experiments that will augment our understanding of DHA-dependent membrane organization in health and disease.
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Affiliation(s)
- Saame Raza Shaikh
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, 600 Moye Blvd, Greenville, NC 28590, USA.
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22
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Membrane-sensitive conformational states of helix 8 in the metabotropic Glu2 receptor, a class C GPCR. PLoS One 2012; 7:e42023. [PMID: 22870276 PMCID: PMC3411606 DOI: 10.1371/journal.pone.0042023] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 06/29/2012] [Indexed: 11/19/2022] Open
Abstract
The recent elucidation of the X-ray structure of several class A GPCRs clearly indicates that the amphipathic helix 8 (H8) is a conserved structural domain in most crystallized GPCRs. Very little is known about the presence and the possible role of an analogous H8 domain in the distantly related class C GPCRs. In this study, we investigated the structural properties for the H8 domain of the mGluR2 receptor, a class C GPCR, by applying extended molecular dynamics simulations. Our study indicates that the amphipathic H8 adopts membrane-sensitive conformational states, which depend on the membrane composition. Cholesterol-rich membranes stabilize the helical structure of H8 whereas cholesterol-depleted membranes induce a disruption of H8. The observed link between membrane cholesterol levels and H8 conformational states suggests that H8 behaves as a sensor of cholesterol concentration.
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23
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Teague H, Ross R, Harris M, Mitchell DC, Shaikh SR. DHA-fluorescent probe is sensitive to membrane order and reveals molecular adaptation of DHA in ordered lipid microdomains. J Nutr Biochem 2012; 24:188-95. [PMID: 22841541 DOI: 10.1016/j.jnutbio.2012.04.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 04/11/2012] [Accepted: 04/18/2012] [Indexed: 12/11/2022]
Abstract
Docosahexaenoic acid (DHA) disrupts the size and order of plasma membrane lipid microdomains in vitro and in vivo. However, it is unknown how the highly disordered structure of DHA mechanistically adapts to increase the order of tightly packed lipid microdomains. Therefore, we studied a novel DHA-Bodipy fluorescent probe to address this issue. We first determined if the DHA-Bodipy probe localized to the plasma membrane of primary B and immortal EL4 cells. Image analysis revealed that DHA-Bodipy localized into the plasma membrane of primary B cells more efficiently than EL4 cells. We then determined if the probe detected changes in plasma membrane order. Quantitative analysis of time-lapse movies established that DHA-Bodipy was sensitive to membrane molecular order. This allowed us to investigate how DHA-Bodipy physically adapted to ordered lipid microdomains. To accomplish this, we employed steady-state and time-resolved fluorescence anisotropy measurements in lipid vesicles of varying composition. Similar to cell culture studies, the probe was highly sensitive to membrane order in lipid vesicles. Moreover, these experiments revealed, relative to controls, that upon incorporation into highly ordered microdomains, DHA-Bodipy underwent an increase in its fluorescence lifetime and molecular order. In addition, the probe displayed a significant reduction in its rotational diffusion compared to controls. Altogether, DHA-Bodipy was highly sensitive to membrane order and revealed for the first time that DHA, despite its flexibility, could become ordered with less rotational motion inside ordered lipid microdomains. Mechanistically, this explains how DHA acyl chains can increase order upon formation of lipid microdomains in vivo.
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Affiliation(s)
- Heather Teague
- Department of Biochemistry and Molecular Biology, East Carolina Diabetes and Obesity Institute, East Carolina University, NC 27834, USA
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24
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Williams JA, Batten SE, Harris M, Rockett BD, Shaikh SR, Stillwell W, Wassall SR. Docosahexaenoic and eicosapentaenoic acids segregate differently between raft and nonraft domains. Biophys J 2012; 103:228-37. [PMID: 22853900 DOI: 10.1016/j.bpj.2012.06.016] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 06/06/2012] [Accepted: 06/12/2012] [Indexed: 01/01/2023] Open
Abstract
Omega-3 polyunsaturated fatty acids (n-3 PUFA), enriched in fish oils, are increasingly recognized to have potential benefits for treating many human afflictions. Despite the importance of PUFA, their molecular mechanism of action remains unclear. One emerging hypothesis is that phospholipids containing n-3 PUFA acyl chains modify the structure and composition of membrane rafts, thus affecting cell signaling. In this study the two major n-3 PUFA found in fish oils, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, are compared. Using solid-state (2)H NMR spectroscopy we explored the molecular organization of 1-[(2)H(31)]palmitoyl-2-eicosapentaenoylphosphatidylcholine (PEPC-d(31)) and 1-[(2)H(31)]palmitoyl-2-docosahexaenoylphosphatidylcholine (PDPC-d(31)) in mixtures with sphingomyelin (SM) and cholesterol (chol). Our results indicate that whereas both PEPC-d(31) and PDPC-d(31) can accumulate into SM-rich/chol-rich raftlike domains, the tendency for DHA to incorporate into rafts is more than twice as great as for EPA. We propose that DHA may be the more bioactive component of fish oil that serves to disrupt lipid raft domain organization. This mechanism represents an evolution in the view of how PUFA remodel membrane architecture.
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Affiliation(s)
- Justin A Williams
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, USA
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25
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Effect of cholesterol on the lateral nanoscale dynamics of fluid membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 41:901-13. [DOI: 10.1007/s00249-012-0826-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 05/03/2012] [Accepted: 05/07/2012] [Indexed: 12/17/2022]
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26
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Coskun U, Simons K. Cell membranes: the lipid perspective. Structure 2012; 19:1543-8. [PMID: 22078554 DOI: 10.1016/j.str.2011.10.010] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/21/2011] [Accepted: 10/24/2011] [Indexed: 12/01/2022]
Abstract
Although cell membranes are packed with proteins mingling with lipids, remarkably little is known about how proteins interact with lipids to carry out their function. Novel analytical tools are revealing the astounding diversity of lipids in membranes. The issue is now to understand the cellular functions of this complexity. In this Perspective, we focus on the interface of integral transmembrane proteins and membrane lipids in eukaryotic cells. Clarifying how proteins and lipids interact with each other will be important for unraveling membrane protein structure and function. Progress toward this goal will be promoted by increasing overlap between different fields that have so far operated without much crosstalk.
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Affiliation(s)
- Unal Coskun
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstraße 108 Dresden, Germany.
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27
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Rockett BD, Teague H, Harris M, Melton M, Williams J, Wassall SR, Shaikh SR. Fish oil increases raft size and membrane order of B cells accompanied by differential effects on function. J Lipid Res 2012; 53:674-85. [PMID: 22315394 DOI: 10.1194/jlr.m021782] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Fish oil (FO) targets lipid microdomain organization to suppress T-cell and macrophage function; however, little is known about this relationship with B cells, especially at the animal level. We previously established that a high FO dose diminished mouse B-cell lipid raft microdomain clustering induced by cross-linking GM1. To establish relevance, here we tested a FO dose modeling human intake on B-cell raft organization relative to a control. Biochemical analysis revealed more docosahexaenoic acid (DHA) incorporated into phosphatidylcholines than phosphatidylethanolamines of detergent-resistant membranes, consistent with supporting studies with model membranes. Subsequent imaging experiments demonstrated that FO increased raft size, GM1 expression, and membrane order upon cross-linking GM1 relative to no cross-linking. Comparative in vitro studies showed some biochemical differences from in vivo measurements but overall revealed that DHA, but not eicosapentaenoic acid (EPA), increased membrane order. Finally, we tested the hypothesis that disrupting rafts with FO would suppress B-cell responses ex vivo. FO enhanced LPS-induced B-cell activation but suppressed B-cell stimulation of transgenic naive CD4(+) T cells. Altogether, our studies with B cells support an emerging model that FO increases raft size and membrane order accompanied by functional changes; furthermore, the results highlight differences in EPA and DHA bioactivity.
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Affiliation(s)
- Benjamin Drew Rockett
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
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28
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Shaikh SR. Biophysical and biochemical mechanisms by which dietary N-3 polyunsaturated fatty acids from fish oil disrupt membrane lipid rafts. J Nutr Biochem 2011; 23:101-5. [PMID: 22137258 DOI: 10.1016/j.jnutbio.2011.07.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/08/2011] [Accepted: 07/11/2011] [Indexed: 12/11/2022]
Abstract
N-3 polyunsaturated fatty acids (PUFAs) from fish oil exert their functional effects by targeting multiple mechanisms. One mechanism to emerge in the past decade is the ability of n-3 PUFA acyl chains to perturb the molecular organization of plasma membrane sphingolipid/cholesterol-enriched lipid raft domains. These domains are nanometer-scale assemblies that coalesce to compartmentalize select proteins for optimal function. Here we review recent evidence on how n-3 PUFAs modify lipid rafts from biophysical and biochemical experiments from several different model systems. A central theme emerges from these studies. N-3 PUFA acyl chains display tremendous conformational flexibility and a low affinity for cholesterol and saturated acyl chains. This unique flexibility of n-3 PUFA acyl chains impacts the organization of inner and outer leaflet lipid rafts by disrupting acyl chain packing and molecular order within rafts. Ultimately, the disruption in raft organization has consequences for protein clustering and thereby signaling. Overall, elucidating the complex mechanisms by which n-3 PUFA acyl chains reorganize membrane architecture will enhance the translation of these fatty acids into the clinic for treating several diseases.
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Affiliation(s)
- Saame Raza Shaikh
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA.
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29
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Shaikh SR, Jolly CA, Chapkin RS. n-3 Polyunsaturated fatty acids exert immunomodulatory effects on lymphocytes by targeting plasma membrane molecular organization. Mol Aspects Med 2011; 33:46-54. [PMID: 22020145 DOI: 10.1016/j.mam.2011.10.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 10/04/2011] [Accepted: 10/09/2011] [Indexed: 01/26/2023]
Abstract
Fish oil, enriched in bioactive n-3 polyunsaturated fatty acids (PUFA), has therapeutic value for the treatment of inflammation-associated disorders. The effects of n-3 PUFAs are pleiotropic and complex; hence, an understanding of their cellular targets and molecular mechanisms of action remains incomplete. Here we focus on recent data indicating n-3 PUFAs exert immunosuppressive effects on the function of effector and regulatory CD4(+) T cells. In addition, we also present emerging evidence that n-3 PUFAs have immunomodulatory effects on B cells. We then focus on one multifaceted mechanism of n-3 PUFAs, which is the alteration of the biophysical and biochemical organization of the plasma membrane. This mechanism is central for downstream signaling, eicosanoid production, transcriptional regulation and cytokine secretion. We highlight recent work demonstrating n-3 PUFA acyl chains in the plasma membrane target the lateral organization of membrane signaling assemblies (i.e. lipid rafts or signaling networks) and de novo phospholipid biosynthesis. We conclude by proposing new functional and mechanistic questions in this area of research that will aid in the development of fish oil as adjuvant therapy for treating unresolved chronic inflammation.
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Affiliation(s)
- Saame Raza Shaikh
- Department of Biochemistry & Molecular Biology and East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA.
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