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Taylor JM, Conboy JC. Issues with lipid probes in flip-flop measurements: A comparative study using sum-frequency vibrational spectroscopy and second-harmonic generation. J Chem Phys 2024; 161:085104. [PMID: 39185850 DOI: 10.1063/5.0226075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 08/11/2024] [Indexed: 08/27/2024] Open
Abstract
Fluorescent lipid probes such as 1-palmitoyl-2-(6-[7-nitro-2-1,3-benzoxadiazol-4-yl]amino-hexanoyl)-sn-glycero-3-phosphocholine (C6 NBD-PC) have been used extensively to study the kinetics of lipid flip-flop. However, the efficacy of these probes as reliable reporters of native lipid translocation has never been tested. In this study, sum-frequency vibrational spectroscopy (SFVS) was used to measure the kinetics of C6 NBD-PC lipid flip-flop and the flip-flop of native lipids in planar supported lipid bilayers. C6 NBD-PC was investigated at concentrations of 1 and 3 mol. % in both chain-matched 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and chain-mismatched 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) to assess the ability of C6 NBD-PC to mimic the behavior of the surrounding matrix lipids. It was observed that C6 NBD-PC exhibited faster flip-flop kinetics compared to the native lipids in both DPPC and DSPC matrices, with notably accelerated rates in the chain-mismatched DSPC system. SFVS was also used to measure the acyl chain orientation and gauche content of C6 NBD-PC in both DPPC and DSPC membranes. In the DSPC matrix (chain mismatched), C6 NBD-PC was more disordered in terms of both gauche content and acyl tilt, whereas it maintained an orientation similar to that of the native lipids in the DPPC matrix (chain matched). In addition, the flip-flop kinetics of C6 NBD-PC were also measured using second-harmonic generation (SHG) spectroscopy, by probing the motion of the NBD chromophore directly. The flip-flop kinetics measured by SHG were consistent with those obtained from SFVS. This study also marks the first instance of phospholipid flip-flop kinetics being measured via SHG. The results of this study clearly demonstrate that C6 NBD-PC does not adequately mimic the behavior of native lipids within a membrane. These findings also highlight the significant impact of the lipid matrix on the flip-flop behavior of the fluorescently labeled lipid, C6 NBD-PC.
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Affiliation(s)
- Joshua M Taylor
- Department of Chemistry, University of Utah, 315 South 1400 East RM. 2020, Salt Lake City, Utah 84112, USA
| | - John C Conboy
- Department of Chemistry, University of Utah, 315 South 1400 East RM. 2020, Salt Lake City, Utah 84112, USA
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2
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Taylor JM, Conboy JC. Sum-frequency vibrational spectroscopy, a tutorial: Applications for the study of lipid membrane structure and dynamics. Biointerphases 2024; 19:031201. [PMID: 38738942 DOI: 10.1116/6.0003594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 04/23/2024] [Indexed: 05/14/2024] Open
Abstract
Planar supported lipid bilayers (PSLBs) are an ideal model for the study of lipid membrane structures and dynamics when using sum-frequency vibrational spectroscopy (SFVS). In this paper, we describe the construction of asymmetric PSLBs and the basic SFVS theory needed to understand and make measurements on these membranes. Several examples are presented, including the determination of phospholipid orientation and measuring phospholipid transmembrane translocation (flip-flop).
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Affiliation(s)
- Joshua M Taylor
- Department of Chemistry, University of Utah, 315 South 1400 East RM. 2020, Salt Lake City, Utah 84112
| | - John C Conboy
- Department of Chemistry, University of Utah, 315 South 1400 East RM. 2020, Salt Lake City, Utah 84112
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3
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Dziura D, Dziura M, Marquardt D. Studying lipid flip-flop in asymmetric liposomes using 1H NMR and TR-SANS. Methods Enzymol 2024; 700:295-328. [PMID: 38971604 DOI: 10.1016/bs.mie.2024.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2024]
Abstract
The specific spatial and temporal distribution of lipids in membranes play a crucial role in determining the biochemical and biophysical properties of the system. In nature, the asymmetric distribution of lipids is a dynamic process with ATP-dependent lipid transporters maintaining asymmetry, and passive transbilayer diffusion, that is, flip-flop, counteracting it. In this chapter, two probe-free techniques, 1H NMR and time-resolved small angle neutron scattering, are described in detail as methods of investigating lipid flip-flop rates in synthetic liposomes that have been generated with an asymmetric bilayer composition.
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Affiliation(s)
- Dominik Dziura
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada
| | - Maksymilian Dziura
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada; Department of Physics, University of Windsor, Windsor, ON, Canada.
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4
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Yao S, Kim SC, Li J, Tang S, Wang X. Phosphatidic acid signaling and function in nuclei. Prog Lipid Res 2024; 93:101267. [PMID: 38154743 PMCID: PMC10843600 DOI: 10.1016/j.plipres.2023.101267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 12/30/2023]
Abstract
Membrane lipidomes are dynamic and their changes generate lipid mediators affecting various biological processes. Phosphatidic acid (PA) has emerged as an important class of lipid mediators involved in a wide range of cellular and physiological responses in plants, animals, and microbes. The regulatory functions of PA have been studied primarily outside the nuclei, but an increasing number of recent studies indicates that some of the PA effects result from its action in nuclei. PA levels in nuclei are dynamic in response to stimuli. Changes in nuclear PA levels can result from activities of enzymes associated with nuclei and/or from movements of PA generated extranuclearly. PA has also been found to interact with proteins involved in nuclear functions, such as transcription factors and proteins undergoing nuclear translocation in response to stimuli. The nuclear action of PA affects various aspects of plant growth, development, and response to stress and environmental changes.
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Affiliation(s)
- Shuaibing Yao
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Sang-Chul Kim
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Jianwu Li
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Shan Tang
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Xuemin Wang
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA.
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5
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Wang Z, Yelamanchili D, Liu J, Gotto AM, Rosales C, Gillard BK, Pownall HJ. Serum opacity factor normalizes erythrocyte morphology in Scarb1 -/- mice in an HDL-free cholesterol-dependent way. J Lipid Res 2023; 64:100456. [PMID: 37821077 PMCID: PMC10641538 DOI: 10.1016/j.jlr.2023.100456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/16/2023] [Accepted: 10/05/2023] [Indexed: 10/13/2023] Open
Abstract
Compared with WT mice, HDL receptor-deficient (Scarb1-/-) mice have higher plasma levels of free cholesterol (FC)-rich HDL and exhibit multiple pathologies associated with a high mol% FC in ovaries, platelets, and erythrocytes, which are reversed by lowering HDL. Bacterial serum opacity factor (SOF) catalyzes the opacification of plasma by targeting and quantitatively converting HDL to neo HDL (HDL remnant), a cholesterol ester-rich microemulsion, and lipid-free APOA1. SOF delivery with an adeno-associated virus (AAVSOF) constitutively lowers plasma HDL-FC and reverses female infertility in Scarb1-/- mice in an HDL-dependent way. We tested whether AAVSOF delivery to Scarb1-/- mice will normalize erythrocyte morphology in an HDL-FC-dependent way. We determined erythrocyte morphology and FC content (mol%) in three groups-WT, untreated Scarb1-/- (control), and Scarb1-/- mice receiving AAVSOF-and correlated these with their respective HDL-mol% FC. Plasma-, HDL-, and tissue-lipid compositions were also determined. Plasma- and HDL-mol% FC positively correlated across all groups. Among Scarb1-/- mice, AAVSOF treatment normalized reticulocyte number, erythrocyte morphology, and erythrocyte-mol% FC. Erythrocyte-mol% FC positively correlated with HDL-mol% FC and with both the number of reticulocytes and abnormal erythrocytes. AAVSOF treatment also reduced FC of extravascular tissues to a lesser extent. HDL-FC spontaneously transfers from plasma HDL to cell membranes. AAVSOF treatment lowers erythrocyte-FC and normalizes erythrocyte morphology and lipid composition by reducing HDL-mol% FC.
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Affiliation(s)
- Ziyi Wang
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Departments of Endocrinology and Xiangya Hospital, Central South University, Changsha, China
| | | | - Jing Liu
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Departments of Endocrinology and Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha, China
| | - Antonio M Gotto
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Baiba K Gillard
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Henry J Pownall
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA.
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6
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Leonhardt SA, Purdy MD, Grover JR, Yang Z, Poulos S, McIntire WE, Tatham EA, Erramilli SK, Nosol K, Lai KK, Ding S, Lu M, Uchil PD, Finzi A, Rein A, Kossiakoff AA, Mothes W, Yeager M. Antiviral HIV-1 SERINC restriction factors disrupt virus membrane asymmetry. Nat Commun 2023; 14:4368. [PMID: 37474505 PMCID: PMC10359404 DOI: 10.1038/s41467-023-39262-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 06/06/2023] [Indexed: 07/22/2023] Open
Abstract
The host proteins SERINC3 and SERINC5 are HIV-1 restriction factors that reduce infectivity when incorporated into the viral envelope. The HIV-1 accessory protein Nef abrogates incorporation of SERINCs via binding to intracellular loop 4 (ICL4). Here, we determine cryoEM maps of full-length human SERINC3 and an ICL4 deletion construct, which reveal that hSERINC3 is comprised of two α-helical bundles connected by a ~ 40-residue, highly tilted, "crossmember" helix. The design resembles non-ATP-dependent lipid transporters. Consistently, purified hSERINCs reconstituted into proteoliposomes induce flipping of phosphatidylserine (PS), phosphatidylethanolamine and phosphatidylcholine. Furthermore, SERINC3, SERINC5 and the scramblase TMEM16F expose PS on the surface of HIV-1 and reduce infectivity, with similar results in MLV. SERINC effects in HIV-1 and MLV are counteracted by Nef and GlycoGag, respectively. Our results demonstrate that SERINCs are membrane transporters that flip lipids, resulting in a loss of membrane asymmetry that is strongly correlated with changes in Env conformation and loss of infectivity.
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Grants
- P01 AI150471 NIAID NIH HHS
- P41 GM103311 NIGMS NIH HHS
- G20 RR031199 NCRR NIH HHS
- R01 GM117372 NIGMS NIH HHS
- U54 AI170856 NIAID NIH HHS
- S10 OD018149 NIH HHS
- U24 GM129539 NIGMS NIH HHS
- S10 RR025067 NCRR NIH HHS
- This work was supported by the National Institutes of Health (NIH) grants P50 AI15046 and U54 AI170856-01 (M.Y., W.M. and A.K.K.), R01 AI154092 (M.Y.), R01 GM117372 (A.A.K.) and P01 AI150471 (W.M.)., by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research, and in part by the NIH Intramural AIDS Targeted Antiviral Program. S.D. and A.F. were supported by the CIHR grant 352417 and a Canada Research Chair. Some molecular graphics and analyses were performed with the University of California, San Francisco Chimera package. Chimera is developed by the Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco (supported by the National Institute of General Medical Sciences Grant P41 GM103311).
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Affiliation(s)
- Susan A Leonhardt
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, University of Miami, Coral Gables, FL, 33146, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Michael D Purdy
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Molecular Electron Microscopy Core, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Jonathan R Grover
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Ziwei Yang
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Sandra Poulos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - William E McIntire
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, University of Miami, Coral Gables, FL, 33146, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Elizabeth A Tatham
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Kamil Nosol
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Kin Kui Lai
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, P.O. Box B, Building 535, Frederick, MD, 21702, USA
| | - Shilei Ding
- Centre de Recherche du CHUM (CRCHUM), Montreal, QC, Canada
| | - Maolin Lu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA
- Department of Cellular and Molecular Biology, University of Texas Health Science Center, Tyler, TX, USA
| | - Pradeep D Uchil
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Andrés Finzi
- Centre de Recherche du CHUM (CRCHUM), Montreal, QC, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, QC, Canada
| | - Alan Rein
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, P.O. Box B, Building 535, Frederick, MD, 21702, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Walther Mothes
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA.
| | - Mark Yeager
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, University of Miami, Coral Gables, FL, 33146, USA.
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
- Department of Chemistry, University of Miami, Coral Gables, FL, 33146, USA.
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL, 33136, USA.
- Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
- Department of Medicine, Division of Cardiovascular Medicine, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
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7
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Nguyen MHL, Dziura D, DiPasquale M, Castillo SR, Kelley EG, Marquardt D. Investigating the cut-off effect of n-alcohols on lipid movement: a biophysical study. SOFT MATTER 2023. [PMID: 37357554 DOI: 10.1039/d2sm01583h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Cellular membranes are responsible for absorbing the effects of external perturbants for the cell's survival. Such perturbants include small ubiquitous molecules like n-alcohols which were observed to exhibit anesthetic capabilities, with this effect tapering off at a cut-off alcohol chain length. To explain this cut-off effect and complement prior biochemical studies, we investigated a series of n-alcohols (with carbon lengths 2-18) and their impact on several bilayer properties, including lipid flip-flop, intervesicular exchange, diffusion, membrane bending rigidity and more. To this end, we employed an array of biophysical techniques such as time-resolved small angle neutron scattering (TR-SANS), small angle X-ray scattering (SAXS), all atomistic and coarse-grained molecular dynamics (MD) simulations, and calcein leakage assays. At an alcohol concentration of 30 mol% of the overall lipid content, TR-SANS showed 1-hexanol (C6OH) increased transverse lipid diffusion, i.e. flip-flop. As alcohol chain length increased from C6 to C10 and longer, lipid flip-flop slowed by factors of 5.6 to 32.2. Intervesicular lipid exchange contrasted these results with only a slight cut-off at alcohol concentrations of 30 mol% but not 10 mol%. SAXS, MD simulations, and leakage assays revealed changes to key bilayer properties, such as bilayer thickness and fluidity, that correlate well with the effects on lipid flip-flop rates. Finally, we tie our results to a defect-mediated pathway for alcohol-induced lipid flip-flop.
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Affiliation(s)
- Michael H L Nguyen
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Dominik Dziura
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Mitchell DiPasquale
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Stuart R Castillo
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
- Department of Physics, University of Windsor, Windsor, Ontario, Canada.
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8
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Filipe HAL, Loura LMS, Moreno MJ. Permeation of a Homologous Series of NBD-Labeled Fatty Amines through Lipid Bilayers: A Molecular Dynamics Study. MEMBRANES 2023; 13:551. [PMID: 37367755 DOI: 10.3390/membranes13060551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/18/2023] [Accepted: 05/20/2023] [Indexed: 06/28/2023]
Abstract
Permeation through biomembranes is ubiquitous for drugs to reach their active sites. Asymmetry of the cell plasma membrane (PM) has been described as having an important role in this process. Here we describe the interaction of a homologous series of 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD)-labeled amphiphiles (NBD-Cn, n = 4 to 16) with lipid bilayers of different compositions (1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphocholine (POPC):cholesterol (1:1) and palmitoylated sphingomyelin (SpM):cholesterol (6:4)), including an asymmetric bilayer. Both unrestrained and umbrella sampling (US) simulations (at varying distances to the bilayer center) were carried out. The free energy profile of NBD-Cn at different depths in the membrane was obtained from the US simulations. The behavior of the amphiphiles during the permeation process was described regarding their orientation, chain elongation, and H-bonding to lipid and water molecules. Permeability coefficients were also calculated for the different amphiphiles of the series, using the inhomogeneous solubility-diffusion model (ISDM). Quantitative agreement with values obtained from kinetic modeling of the permeation process could not be obtained. However, for the longer, and more hydrophobic amphiphiles, the variation trend along the homologous series was qualitatively better matched by the ISDM when the equilibrium location of each amphiphile was taken as reference (ΔG = 0), compared to the usual choice of bulk water.
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Affiliation(s)
- Hugo A L Filipe
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal
- CPIRN-IPG-Center of Potential and Innovation of Natural Resources, Polytechnic Institute of Guarda, 6300-559 Guarda, Portugal
| | - Luís M S Loura
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-535 Coimbra, Portugal
- Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Maria João Moreno
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-535 Coimbra, Portugal
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal
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9
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Blake MJ, Castillo HB, Curtis AE, Calhoun TR. Facilitating flip-flop: Structural tuning of molecule-membrane interactions in living bacteria. Biophys J 2023; 122:1735-1747. [PMID: 37041744 PMCID: PMC10209030 DOI: 10.1016/j.bpj.2023.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/17/2023] [Accepted: 04/04/2023] [Indexed: 04/13/2023] Open
Abstract
The first barrier that a small molecule must overcome before trespassing into a living cell is the lipid bilayer surrounding the intracellular content. It is imperative, therefore, to understand how the structure of a small molecule influences its fate in this region. Through the use of second harmonic generation, we show how the differing degrees of ionic headgroups, conjugated system, and branched hydrocarbon tail disparities of a series of four styryl dye molecules influence the propensity to "flip-flop" or to be further organized in the outer leaflet by the membrane. We show here that initial adsorption experiments match previous studies on model systems; however, more complex dynamics are observed over time. Aside from probe molecule structure, these dynamics also vary between cell species and can deviate from trends reported based on model membranes. Specifically, we show here that the membrane composition is an important factor to consider for headgroup-mediated small-molecule dynamics. Overall, the findings presented here on how structural variability of small molecules impacts their initial adsorption and eventual destinations within membranes in the context of living cells could have practical applications in antibiotic and drug adjuvant design.
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Affiliation(s)
- Marea J Blake
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee
| | - Hannah B Castillo
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee
| | - Anna E Curtis
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee
| | - Tessa R Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee.
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10
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Miyajima A, Nakao H, Ikeda K, Nakano M. The Nanometer-Scale Proximity of Bilayers Facilitates Intermembrane Lipid Transfer. J Phys Chem Lett 2023; 14:4172-4178. [PMID: 37114850 DOI: 10.1021/acs.jpclett.3c00154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Biological membranes approach one another in various biological phenomena, such as lipid transport at membrane contact sites and membrane fusion. The proximity of two bilayers may cause environmental changes in the interbilayer space and alter the dynamics of lipid molecules. Here, we investigate the structure and dynamics of vesicles aggregated due to the depletion attraction caused by polyethylene glycol (PEG) through static and dynamic small-angle neutron scattering. Manipulation of the interbilayer distance using PEG-conjugated lipids reveals that lipid molecules rapidly transfer between vesicles when the opposing bilayers are within ∼2 nm of each other. This distance corresponds to a region in which water molecules are more structured than in bulk water. Kinetic analysis suggests that the decrease in water entropy is responsible for the progression of lipid transfer. These results provide a basis for understanding the dynamic function of biomembranes in confined regions.
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Affiliation(s)
- Ayari Miyajima
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Keisuke Ikeda
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
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11
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Bogdanov M. Renovating a double fence with or without notifying the next door and across the street neighbors: why the biogenic cytoplasmic membrane of Gram-negative bacteria display asymmetry? Emerg Top Life Sci 2023; 7:137-150. [PMID: 36960750 PMCID: PMC10725183 DOI: 10.1042/etls20230042] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 03/03/2023] [Accepted: 03/13/2023] [Indexed: 03/25/2023]
Abstract
The complex two-membrane organization of the envelope of Gram-negative bacteria imposes an unique biosynthetic and topological constraints that can affect translocation of lipids and proteins synthesized on the cytoplasm facing leaflet of the cytoplasmic (inner) membrane (IM), across the IM and between the IM and outer membrane (OM). Balanced growth of two membranes and continuous loss of phospholipids in the periplasmic leaflet of the IM as metabolic precursors for envelope components and for translocation to the OM requires a constant supply of phospholipids in the IM cytosolic leaflet. At present we have no explanation as to why the biogenic E. coli IM displays asymmetry. Lipid asymmetry is largely related to highly entropically disfavored, unequal headgroup and acyl group asymmetries which are usually actively maintained by active mechanisms. However, these mechanisms are largely unknown for bacteria. Alternatively, lipid asymmetry in biogenic IM could be metabolically controlled in order to maintain uniform bilayer growth and asymmetric transmembrane arrangement by balancing temporally the net rates of synthesis and flip-flop, inter IM and OM bidirectional flows and bilayer chemical and physical properties as spontaneous response. Does such flippase-less or 'lipid only", 'passive' mechanism of generation and maintenance of lipid asymmetry exists in the IM? The driving force for IM asymmetry can arise from the packing requirements imposed upon the bilayer system during cell division through disproportional distribution of two negatively curved phospholipids, phosphatidylethanolamine and cardiolipin, with consistent reciprocal tendency to increase and decrease lipid order in each membrane leaflet respectively.
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Affiliation(s)
- Mikhail Bogdanov
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, TX 77030, U.S.A
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12
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Serrano-Buitrago S, Muñoz-Úbeda M, Almendro-Vedia VG, Sánchez-Camacho J, Maroto BL, Moreno F, Bañuelos J, García-Moreno I, López-Montero I, de la Moya S. Polar ammoniostyryls easily converting a clickable lipophilic BODIPY in an advanced plasma membrane probe. J Mater Chem B 2023; 11:2108-2114. [PMID: 36808432 DOI: 10.1039/d2tb02516g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
A very simple, small and symmetric, but highly bright, photostable and functionalizable molecular probe for plasma membrane (PM) has been developed from an accessible, lipophilic and clickable organic dye based on BODIPY. To this aim, two lateral polar ammoniostyryl groups were easily linked to increase the amphiphilicity of the probe and thus its lipid membrane partitioning. Compared to the BODIPY precursor, the transversal diffusion across lipid bilayers of the ammoniostyryled BODIPY probe was highly reduced, as evidenced by fluorescence confocal microscopy on model membranes built up as giant unilamellar vesicles (GUVs). Moreover, the ammoniostyryl groups endow the new BODIPY probe with the ability to optically work (excitation and emission) in the bioimaging-useful red region, as shown by staining of the plasma membrane of living mouse embryonic fibroblasts (MEFs). Upon incubation, this fluorescent probe rapidly entered the cell through the endosomal pathway. By blocking the endocytic trafficking at 4 °C, the probe was confined within the PM of MEFs. Our experiments show the developed ammoniostyrylated BODIPY as a suitable PM fluorescent probe, and confirm the synthetic approach for advancing PM probes, imaging and science.
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Affiliation(s)
- Sergio Serrano-Buitrago
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | - Mónica Muñoz-Úbeda
- Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12), Avda. de Córdoba s/n, 28041, Madrid, Spain.,Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | - Víctor G Almendro-Vedia
- Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12), Avda. de Córdoba s/n, 28041, Madrid, Spain.,Departamento de Farmacia Galénica y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Juan Sánchez-Camacho
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | - Beatriz L Maroto
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | - Florencio Moreno
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
| | - Jorge Bañuelos
- Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV-EHU), Barrio Sarriena s/n, 48080, Bilbao, Spain
| | - Inmaculada García-Moreno
- Departamento de Química-Física de Materiales, Instituto de Química Física Rocasolano, C.S.I.C., 28006, Madrid, Spain
| | - Iván López-Montero
- Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12), Avda. de Córdoba s/n, 28041, Madrid, Spain.,Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain. .,Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo de Juan XXIII 1, 28040, Madrid, Spain
| | - Santiago de la Moya
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
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13
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Yasuda T, Watanabe H, Hirosawa KM, Suzuki KGN, Suga K, Hanashima S. Fluorescence Spectroscopic Analysis of Lateral and Transbilayer Fluidity of Exosome Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14695-14703. [PMID: 36421004 PMCID: PMC9731264 DOI: 10.1021/acs.langmuir.2c02258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 11/10/2022] [Indexed: 06/16/2023]
Abstract
Exosomes are small extracellular vesicles (sEVs) involved in distal cell-cell communication and cancer migration by transferring functional cargo molecules. Membrane domains similar to lipid rafts are assumed to occur in exosome membranes and are involved in interactions with target cells. However, the bilayer membrane properties of these small vesicles have not been fully investigated. Therefore, we examined the fluidity, lateral domain separation, and transbilayer asymmetry of exosome membranes using fluorescence spectroscopy. Although there were some differences between the exosomes, TMA-DPH anisotropy showing moderate lipid chain order indicated that ordered phases comprised a significant proportion of exosome membranes. Selective TEMPO quenching of the TMA-DPH fluorescence in the liquid-disordered phase indicated that 40-50% of the exosome membrane area belonged to the ordered phase based on a phase-separated model. Furthermore, NBD-PC in the outer leaflet showed longer fluorescence lifetimes than those in the inner leaflets. Therefore, the exosome membranes maintained transbilayer asymmetry with a topology similar to that of the plasma membranes. In addition, the lateral and transbilayer orders of exosome membranes obtained from different cell lines varied, probably depending on the different membrane lipid components and compositions partially derived from donor cells. As these higher membrane orders and asymmetric topologies are similar to those of cell membranes with lipid rafts, raft-like functional domains are possibly enriched on exosome membranes. These domains likely play key roles in the biological functions and cellular uptake of exosomes by facilitating selective membrane interactions with target organs.
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Affiliation(s)
- Tomokazu Yasuda
- Graduate
School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka560-0043, Japan
| | - Hirofumi Watanabe
- Graduate
School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka560-0043, Japan
| | - Koichiro M. Hirosawa
- Institute
for Glyco-core Research (iGCORE), Gifu University, 1-1 Yanagido, Gifu501-1193, Japan
| | - Kenichi G. N. Suzuki
- Institute
for Glyco-core Research (iGCORE), Gifu University, 1-1 Yanagido, Gifu501-1193, Japan
| | - Keishi Suga
- Department
of Chemical Engineering, Tohoku University, 6-6-07, Aoba, Aramaki-aza, Aoba-ku, Sendai, Miyagi980-8579, Japan
| | - Shinya Hanashima
- Graduate
School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka560-0043, Japan
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14
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Kim SC, Yao S, Zhang Q, Wang X. Phospholipase Dδ and phosphatidic acid mediate heat-induced nuclear localization of glyceraldehyde-3-phosphate dehydrogenase in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 112:786-799. [PMID: 36111506 PMCID: PMC9831026 DOI: 10.1111/tpj.15981] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 09/14/2022] [Indexed: 06/15/2023]
Abstract
Cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) is a glycolytic enzyme, but undergoes stress-induced nuclear translocation for moonlighting. We previously reported that in response to heat stress, GAPC accumulated in the nucleus to modulate transcription and thermotolerance. Here we show a cellular and molecular mechanism that mediates heat-induced nuclear translocation of cytosolic GAPC in Arabidopsis thaliana. Heat-induced GAPC nuclear accumulation and plant heat tolerance were reduced in Arabidopsis phospholipase D (PLD) knockout mutants of pldδ and pldα1pldδ, but not of pldα1. These changes were restored to wild type by genetic complementation with active PLDδ, but not with catalytically inactive PLDδ. GAPC overexpression enhanced the seedling thermotolerance and the expression of heat-inducible genes, but this effect was abolished in the pldδ background. Heat stress elevated the levels of the PLD product phosphatidic acid (PA) in the nucleus in wild type, but not in pldδ plants. Lipid labeling demonstrated the heat-induced nuclear co-localization of PA and GAPC, which was impaired by zinc, which inhibited the PA-GAPC interaction, and by the membrane trafficking inhibitor brefeldin A (BFA). The GAPC nuclear accumulation and seedling thermotolerance were also decreased by treatment with zinc or BFA. Our data suggest that PLDδ and PA are critical for the heat-induced nuclear translocation of GAPC. We propose that PLDδ-produced PA mediates the process via lipid-protein interaction and that the lipid mediation acts as a cellular conduit linking stress perturbations at cell membranes to nuclear functions in plants coping with heat stress.
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Affiliation(s)
- Sang-Chul Kim
- Department of Biology, University of Missouri-St. Louis, St. Louis, Missouri 63121, USA
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA, and
| | - Shuaibing Yao
- Department of Biology, University of Missouri-St. Louis, St. Louis, Missouri 63121, USA
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA, and
| | - Qun Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Xuemin Wang
- Department of Biology, University of Missouri-St. Louis, St. Louis, Missouri 63121, USA
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA, and
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15
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Nakao H, Nakano M. Flip-Flop Promotion Mechanisms by Model Transmembrane Peptides. Chem Pharm Bull (Tokyo) 2022; 70:519-523. [DOI: 10.1248/cpb.c22-00133] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama
| | - Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama
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16
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Nakano M, Nakao H, Yoshida S, Fukuda M, Imai M, Ikeda K. Energetic and Structural Insights into Phospholipid Transfer from Membranes with Different Curvatures by Time-Resolved Neutron Scattering. J Phys Chem Lett 2022; 13:6024-6030. [PMID: 35748601 DOI: 10.1021/acs.jpclett.2c01080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Understanding how lipid dynamics change with membrane curvature is important given that biological membranes constantly change their curvature and morphology through membrane fusion and endo-/exocytosis. Here, we used time-resolved small-angle neutron scattering and time-resolved fluorescence to characterize the properties and dynamics of phospholipids in vesicles with different curvatures. Dissociation of phospholipids from vesicles required traversing an energy barrier comprising positive enthalpy and negative entropy. However, lipids in membranes with high positive curvature have dense acyl chain packing and loose headgroup packing, leading to hydrophobic hydration due to water penetration into the membrane. These properties were found to lower the hydrophobic hydration enhancement associated with phospholipid dissociation and mitigate the acyl chain packing of lipids adjacent to the space created by the lipid dissociation, resulting in an increase in activation entropy. The results of this study provide important insights into the functions of biomembranes in relation to their dynamic structural changes.
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Affiliation(s)
- Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Shigeharu Yoshida
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masakazu Fukuda
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Manjiro Imai
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Keisuke Ikeda
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
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17
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Nielsen J, Lund R. Molecular Transport and Growth of Lipid Vesicles Exposed to Antimicrobial Peptides. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:374-384. [PMID: 34902242 PMCID: PMC8757467 DOI: 10.1021/acs.langmuir.1c02736] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/01/2021] [Indexed: 05/20/2023]
Abstract
It is well-known that lipids constituting the cytoplasmic membrane undergo continuous reorganization to maintain the appropriate composition important for the integrity of the cell. The transport of lipids is controlled by mainly membrane proteins, but also spontaneous lipid transport between leaflets, lipid "flip-flop", occurs. These processes do not only occur spontaneously under equilibrium, but also promote structural rearrangements, morphological transitions, and growth processes. It has previously been shown that intravesicular lipid "flip-flop" and intervesicular lipid exchange under equilibrium can be deduced indirectly from contrast variation time-resolved small-angle neutron scattering (TR-SANS) where the molecules are "tagged" using hydrogen/deuterium (H/D) substitution. In this work, we show that this technique can be extended to simultaneously detect changes in the growth and the lipid "flip-flop" and exchange rates induced by a peptide additive on lipid vesicles consisting of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine), d-DMPC (1,2-dimyristoyl-d54-sn-glycero-3-phosphocholine), DMPG (1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol)), and small amounts of DMPE-PEG (1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000]). Changes in the overall size were independently monitored using dynamic light scattering (DLS). We find that the antimicrobial peptide, indolicidin, accelerates lipid transport and additionally induces limited vesicular growth. Moreover, in TR-SANS experiments using partially labeled lipid mixtures to separately study the kinetics of the lipid components, we show that, whereas peptide addition affects both lipids similarly, DMPG exhibits faster kinetics. We find that vesicular growth is mainly associated with peptide-mediated lipid reorganization that only slightly affects the overall exchange kinetics. This is confirmed by a TR-SANS experiment of vesicles preincubated with peptide showing that after pre-equilibration the kinetics are only slightly slower.
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Affiliation(s)
| | - Reidar Lund
- Department of Chemistry, University of Oslo, Postboks 1033 Blindern, Oslo 0315, Norway
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18
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Nguyen MHL, DiPasquale M, Castillo SR, Marquardt D. Time-Resolved SANS to Measure Monomer Inter-Bilayer Exchange and Intra-Bilayer Translocation. Methods Mol Biol 2022; 2402:151-161. [PMID: 34854043 DOI: 10.1007/978-1-0716-1843-1_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The monomeric exchange kinetics of sub-micron particles provide insight into their stability and dynamism. Traditional techniques used to measure the intra- and inter-particle exchange often require monitoring the transfer of bulky and perturbing fluorescent labels. Time-resolved small angle neutron scattering (TR-SANS) overcomes these flaws by isotope labeling, allowing for the monomeric exchange rate determination of unperturbed, stress-free particles. Here, we describe TR-SANS in detail and novel applications of the technique.
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Affiliation(s)
- Michael H L Nguyen
- Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, Canada
| | - Mitchell DiPasquale
- Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, Canada
| | - Stuart R Castillo
- Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, Canada
| | - Drew Marquardt
- Department of Chemistry & Biochemistry, University of Windsor, Windsor, ON, Canada.
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19
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Perez-Salas U, Garg S, Gerelli Y, Porcar L. Deciphering lipid transfer between and within membranes with time-resolved small-angle neutron scattering. CURRENT TOPICS IN MEMBRANES 2021; 88:359-412. [PMID: 34862031 DOI: 10.1016/bs.ctm.2021.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This review focuses on time-resolved neutron scattering, particularly time-resolved small angle neutron scattering (TR-SANS), as a powerful in situ noninvasive technique to investigate intra- and intermembrane transport and distribution of lipids and sterols in lipid membranes. In contrast to using molecular analogues with potentially large chemical tags that can significantly alter transport properties, small angle neutron scattering relies on the relative amounts of the two most abundant isotope forms of hydrogen: protium and deuterium to detect complex membrane architectures and transport processes unambiguously. This review discusses advances in our understanding of the mechanisms that sustain lipid asymmetry in membranes-a key feature of the plasma membrane of cells-as well as the transport of lipids between membranes, which is an essential metabolic process.
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Affiliation(s)
- Ursula Perez-Salas
- Physics Department, University of Illinois at Chicago, Chicago, IL, United States.
| | - Sumit Garg
- Physics Department, University of Illinois at Chicago, Chicago, IL, United States
| | - Yuri Gerelli
- Department of Life and Environmental Sciences, Universita` Politecnica delle Marche, Ancona, Italy
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20
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Rogers JR, Espinoza Garcia G, Geissler PL. Membrane hydrophobicity determines the activation free energy of passive lipid transport. Biophys J 2021; 120:3718-3731. [PMID: 34302793 PMCID: PMC8456290 DOI: 10.1016/j.bpj.2021.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/07/2021] [Accepted: 07/19/2021] [Indexed: 12/16/2022] Open
Abstract
The collective behavior of lipids with diverse chemical and physical features determines a membrane's thermodynamic properties. Yet, the influence of lipid physicochemical properties on lipid dynamics, in particular interbilayer transport, remains underexplored. Here, we systematically investigate how the activation free energy of passive lipid transport depends on lipid chemistry and membrane phase. Through all-atom molecular dynamics simulations of 11 chemically distinct glycerophospholipids, we determine how lipid acyl chain length, unsaturation, and headgroup influence the free energy barriers for two elementary steps of lipid transport: lipid desorption, which is rate limiting, and lipid insertion into a membrane. Consistent with previous experimental measurements, we find that lipids with longer, saturated acyl chains have increased activation free energies compared to lipids with shorter, unsaturated chains. Lipids with different headgroups exhibit a range of activation free energies; however, no clear trend based solely on chemical structure can be identified, mirroring difficulties in the interpretation of previous experimental results. Compared to liquid-crystalline phase membranes, gel phase membranes exhibit substantially increased free energy barriers. Overall, we find that the activation free energy depends on a lipid's local hydrophobic environment in a membrane and that the free energy barrier for lipid insertion depends on a membrane's interfacial hydrophobicity. Both of these properties can be altered through changes in lipid acyl chain length, lipid headgroup, and membrane phase. Thus, the rate of lipid transport can be tuned through subtle changes in local membrane composition and order, suggesting an unappreciated role for nanoscale membrane domains in regulating cellular lipid dynamics.
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Affiliation(s)
- Julia R Rogers
- Department of Chemistry, University of California Berkeley, Berkeley, California.
| | | | - Phillip L Geissler
- Department of Chemistry, University of California Berkeley, Berkeley, California; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California.
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21
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Johansen NT, Luchini A, Tidemand FG, Orioli S, Martel A, Porcar L, Arleth L, Pedersen MC. Structural and Biophysical Properties of Supercharged and Circularized Nanodiscs. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6681-6690. [PMID: 34038130 DOI: 10.1021/acs.langmuir.1c00560] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nanodiscs based on membrane scaffold proteins (MSPs) and phospholipids are used as membrane mimics to stabilize membrane proteins in solution for structural and functional studies. Combining small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and time-resolved small-angle neutron scattering (TR-SANS), we characterized the structure and lipid bilayer properties of five different nanodiscs made with dimyristoylphosphatidylcholine and different MSPs varying in size, charge, and circularization. Our SAXS modeling showed that the structural parameters of the embedded lipids are all similar, irrespective of the MSP properties. DSC showed that the lipid packing is not homogeneous in the nanodiscs and that a 20 Å wide boundary layer of lipids with perturbed packing is located close to the MSP, while the packing of central lipids is tighter than in large unilamellar vesicles. Finally, TR-SANS showed that lipid exchange rates in nanodiscs decrease with increasing nanodisc size and are lower for the nanodiscs made with supercharged MSPs compared to conventional nanodiscs. Altogether, the results provide a thorough biophysical understanding of the nanodisc as a model membrane system, which is important in order to carry out and interpret experiments on membrane proteins embedded in such systems.
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Affiliation(s)
- Nicolai Tidemand Johansen
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
| | - Alessandra Luchini
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
| | - Frederik Grønbæk Tidemand
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
| | - Simone Orioli
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
- Structural Biology and NMR Laboratory and Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Anne Martel
- Institut Laue Langevin, 38000 Grenoble, France
| | | | - Lise Arleth
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
| | - Martin Cramer Pedersen
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
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22
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Shukla S, Baumgart T. Enzymatic trans-bilayer lipid transport: Mechanisms, efficiencies, slippage, and membrane curvature. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2021; 1863:183534. [PMID: 33340491 PMCID: PMC8351443 DOI: 10.1016/j.bbamem.2020.183534] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/03/2020] [Accepted: 12/07/2020] [Indexed: 12/12/2022]
Abstract
The eukaryotic plasma membrane's lipid composition is found to be ubiquitously asymmetric comparing inner and outer leaflets. This membrane lipid asymmetry plays a crucial role in diverse cellular processes critical for cell survival. A specialized set of transmembrane proteins called translocases, or flippases, have evolved to maintain this membrane lipid asymmetry in an energy-dependent manner. One potential consequence of local variations in membrane lipid asymmetry is membrane remodeling, which is essential for cellular processes such as intracellular trafficking. Recently, there has been a surge in the identification and characterization of flippases, which has significantly advanced the understanding of their functional mechanisms. Furthermore, there are intriguing possibilities for a coupling between membrane curvature and flippase activity. In this review we highlight studies that link membrane shape and remodeling to differential stresses generated by the activity of lipid flippases with an emphasis on data obtained through model membrane systems. We review the common mechanistic models of flippase-mediated lipid flipping and discuss common techniques used to test lipid flippase activity. We then compare the existing data on lipid translocation rates by flippases and conclude with potential future directions for this field.
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Affiliation(s)
- Sankalp Shukla
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Tobias Baumgart
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, United States.
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23
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Nguyen MHL, DiPasquale M, Rickeard BW, Yip CG, Greco KN, Kelley EG, Marquardt D. Time-resolved SANS reveals pore-forming peptides cause rapid lipid reorganization. NEW J CHEM 2021. [DOI: 10.1039/d0nj04717a] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Time-resolved SANS showed alamethicin and melittin promote DMPC lipid vesicle mixing and perturb DMPC kinetics in similar ways.
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Affiliation(s)
| | | | - Brett W. Rickeard
- Department of Chemistry and Biochemistry
- University of Windsor
- Windsor
- Canada
| | - Caesar G. Yip
- Department of Chemistry and Biochemistry
- University of Windsor
- Windsor
- Canada
| | - Kaity N. Greco
- Department of Chemistry and Biochemistry
- University of Windsor
- Windsor
- Canada
| | - Elizabeth G. Kelley
- NIST Center for Neutron Research
- National Institute of Standards and Technology
- Gaithersburg
- USA
| | - Drew Marquardt
- Department of Chemistry and Biochemistry
- University of Windsor
- Windsor
- Canada
- Department of Physics
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24
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Nielsen JE, Bjørnestad VA, Pipich V, Jenssen H, Lund R. Beyond structural models for the mode of action: How natural antimicrobial peptides affect lipid transport. J Colloid Interface Sci 2021; 582:793-802. [DOI: 10.1016/j.jcis.2020.08.094] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/21/2020] [Accepted: 08/25/2020] [Indexed: 12/18/2022]
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25
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Nielsen JE, Prévost SF, Jenssen H, Lund R. Impact of antimicrobial peptides on E. coli-mimicking lipid model membranes: correlating structural and dynamic effects using scattering methods. Faraday Discuss 2021; 232:203-217. [DOI: 10.1039/d0fd00046a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using X-rays and neutrons we address the effect of AMPs on structure and dynamics of lipids in bacterial model membranes.
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Affiliation(s)
| | | | - Håvard Jenssen
- Department of Science and Environment, Roskilde University, 4000 Roskilde, Denmark
| | - Reidar Lund
- Department of Chemistry, University of Oslo, 0315 Oslo, Norway
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26
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Lipid flip-flop and desorption from supported lipid bilayers is independent of curvature. PLoS One 2020; 15:e0244460. [PMID: 33378379 PMCID: PMC7773258 DOI: 10.1371/journal.pone.0244460] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 12/09/2020] [Indexed: 01/10/2023] Open
Abstract
Flip-flop of lipids of the lipid bilayer (LBL) constituting the plasma membrane (PM) plays a crucial role in a myriad of events ranging from cellular signaling and regulation of cell shapes to cell homeostasis, membrane asymmetry, phagocytosis, and cell apoptosis. While extensive research has been conducted to probe the lipid flip flop of planar lipid bilayers (LBLs), less is known regarding lipid flip-flop for highly curved, nanoscopic LBL systems despite the vast importance of membrane curvature in defining the morphology of cells and organelles and in maintaining a variety of cellular functions, enabling trafficking, and recruiting and localizing shape-responsive proteins. In this paper, we conduct molecular dynamics (MD) simulations to study the energetics, structure, and configuration of a lipid molecule undergoing flip-flop and desorption in a highly curved LBL, represented as a nanoparticle-supported lipid bilayer (NPSLBL) system. We compare our findings against those of a planar substrate supported lipid bilayer (PSSLBL). Our MD simulation results reveal that despite the vast differences in the curvature and other curvature-dictated properties (e.g., lipid packing fraction, difference in the number of lipids between inner and outer leaflets, etc.) between the NPSLBL and the PSSLBL, the energetics of lipid flip-flop and lipid desorption as well as the configuration of the lipid molecule undergoing lipid flip-flop are very similar for the NPSLBL and the PSSLBL. In other words, our results establish that the curvature of the LBL plays an insignificant role in lipid flip-flop and desorption.
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27
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Jeong J, Kim C. Flip‐Flop
Movement of Phospholipids in 1,2‐Dimyristoyl‐sn‐glycero‐3‐phosphocholine/1,2‐Dihexanoyl‐sn‐glycero‐3‐phosphocholine Vesicles. B KOREAN CHEM SOC 2020. [DOI: 10.1002/bkcs.12190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jinju Jeong
- Department of Chemistry Hannam University Daejeon 34054 Korea
| | - Chul Kim
- Department of Chemistry Hannam University Daejeon 34054 Korea
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28
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Rogers JR, Geissler PL. Breakage of Hydrophobic Contacts Limits the Rate of Passive Lipid Exchange between Membranes. J Phys Chem B 2020; 124:5884-5898. [DOI: 10.1021/acs.jpcb.0c04139] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julia R. Rogers
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Phillip L. Geissler
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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29
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Miller LN, Brewer WT, Williams JD, Fozo EM, Calhoun TR. Second Harmonic Generation Spectroscopy of Membrane Probe Dynamics in Gram-Positive Bacteria. Biophys J 2019; 117:1419-1428. [PMID: 31586521 DOI: 10.1016/j.bpj.2019.09.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 09/11/2019] [Accepted: 09/13/2019] [Indexed: 11/17/2022] Open
Abstract
Bacterial membranes are complex mixtures with dispersity that is dynamic over scales of both space and time. To capture adsorption onto and transport within these mixtures, we conduct simultaneous second harmonic generation (SHG) and two-photon fluorescence measurements on two different gram-positive bacterial species as the cells uptake membrane-specific probe molecules. Our results show that SHG not only can monitor the movement of small molecules across membrane leaflets but also is sensitive to higher-level ordering of the molecules within the membrane. Further, we show that the membranes of Staphylococcus aureus remain more dynamic after longer times at room temperature in comparison to Enterococcus faecalis. Our findings provide insight into the variability of activities seen between structurally similar molecules in gram-positive bacteria while also demonstrating the power of SHG to examine these dynamics.
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Affiliation(s)
- Lindsey N Miller
- Department of Chemistry, University of Tennesseee, Knoxville, Tennessee
| | - William T Brewer
- Department of Microbiology, University of Tennesseee, Knoxville, Tennessee
| | - Julia D Williams
- Department of Microbiology, University of Tennesseee, Knoxville, Tennessee
| | - Elizabeth M Fozo
- Department of Microbiology, University of Tennesseee, Knoxville, Tennessee
| | - Tessa R Calhoun
- Department of Chemistry, University of Tennesseee, Knoxville, Tennessee.
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30
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Garg S, Liu Y, Perez-Salas U, Porcar L, Butler PD. Anomalous inter-membrane cholesterol transport in fluid phase phosphoserine vesicles driven by headgroup ordered to disordered entropic transition. Chem Phys Lipids 2019; 223:104779. [PMID: 31153912 PMCID: PMC11132670 DOI: 10.1016/j.chemphyslip.2019.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 05/20/2019] [Indexed: 10/26/2022]
Abstract
POPS is highly enriched in the inner leaflet of the plasma membrane. Here we present measurements of inter-membrane cholesterol transport rates in POPS vesicles. We find that the cholesterol transport kinetics are not only an order of magnitude slower than in POPC lipids at near physiological temperatures, they exhibit a surprising discontinuous Arrhenius behavior around 48 °C. Moreover, thermodynamic analysis suggests that for biologically relevant temperatures, below the discontinuity, the exchange of cholesterol is entropically dominated while it is enthalpically driven, as is the case in POPC vesicles, above that discontinuity. Using the polar fluorescent probe Laurdan we found that POPS fluid membranes retain a large degree of order in the headgroup region for temperatures below the discontinuity but undergo an order-to-disorder transition in the region coinciding with the discontinuity in the transport of cholesterol in POPS membranes providing an explanation not only for the discontinuity but for the entropic dominance at physiological temperatures.
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Affiliation(s)
- Sumit Garg
- Physics Department, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Yangmingyue Liu
- Physics Department, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Ursula Perez-Salas
- Physics Department, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Lionel Porcar
- Institut Laue Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Paul D Butler
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA
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31
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Hofmann C, Roth G, Hirsch T, Duerkop A, Baeumner AJ. Tethering functionality to lipid interfaces by a fast, simple and controllable post synthesis method. Colloids Surf B Biointerfaces 2019; 181:325-332. [PMID: 31154143 DOI: 10.1016/j.colsurfb.2019.05.049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/13/2019] [Accepted: 05/21/2019] [Indexed: 01/10/2023]
Abstract
HYPOTHESIS Liposomes require careful control of the surface design to ensure colloidal stability in complex matrices and target-specific binding to desired receptor units. Ideally, surface functionalization should be smart and controllable in terms of composition which is seldomly achieved by conventional methods. Therefore, a new strategy (insertion method) was developed and compared to the standard method (modification post-synthesis) using the model receptor biotin. EXPERIMENTS Dipalmitoylphosphatidylethanolamine-biotin (DPPE-biotin) was used in both procedures, lipopeptide-biotin and cholesterol-biotin were tested additionally for insertion into the intact lipid bilayer. The insertion method was optimized regarding incubation time, temperature and vesicle stability. The biotinylated vesicles of both functionalization methods were characterized with respect to their size, ζ-potential and binding functionality. FINDINGS Standard incorporation resulted in large variations in insertion-efficiency, high batch-to-batch differences, and an incorporation limit of 4 mol%. Best results were obtained through effortless insertion of the lipopeptide-biotin at room temperature. The concentration-controlled functionalization of liposomes (up to 10 mol%) could easily be monitored by the ζ-potential, resulted in reliable, quantitative binding to streptavidin and did not affect the analytical properties of the nanomaterial. This offers the possibility for a general modification strategy for lipid-based nanomaterials ideal for assay optimizations or multi-analyte detection.
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Affiliation(s)
- Carola Hofmann
- University of Regensburg, Institute of Analytical Chemistry, Chemo- and Biosensors, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Guenter Roth
- ZBSA - (Center for Biological Systems Analysis), University of Freiburg, Habsburgerstraße 46, 79104 Freiburg, Germany; BIOSS - Center for Biological Signaling Studies, University Freiburg, Schänzlestrasse 21, 79104 Freiburg, Germany
| | - Thomas Hirsch
- University of Regensburg, Institute of Analytical Chemistry, Chemo- and Biosensors, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Axel Duerkop
- University of Regensburg, Institute of Analytical Chemistry, Chemo- and Biosensors, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Antje J Baeumner
- University of Regensburg, Institute of Analytical Chemistry, Chemo- and Biosensors, Universitätsstraße 31, 93053 Regensburg, Germany.
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32
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Abstract
The lipid bilayer, together with embedded proteins, is the central structure in biomembranes. While artificial lipid bilayers are useful to model natural membranes, they are generally symmetric, with the same membrane lipid composition in each lipid monolayer (leaflet). In contrast, natural membranes are often asymmetric, with different lipids in each leaflet. To prepare asymmetric lipid vesicles, we developed cyclodextrin-catalyzed phospholipid exchange procedures. The basic method is that an excess of vesicles with one set of lipids (the donor vesicles) is mixed with a second set of vesicles (acceptor vesicles) with a different set of lipids. Cyclodextrin is introduced into the external aqueous solution, so that lipids in the outer leaflet of the vesicles bind to it and are shuttled between the vesicles. At equilibrium, the lipids in the outer leaflet of the acceptor vesicles are replaced by those from the donor vesicles. The exchanged acceptor vesicles are then isolated. Asymmetric vesicles are versatile in terms of vesicle sizes and lipid compositions that can be prepared. Measuring asymmetry is often difficult. A variety of assays can be used to measure the extent of asymmetry, but most are specific for one particular membrane lipid type or class, and there are none that can be used in all situations. Studies using asymmetric vesicles have begun to explore how asymmetry influences lipid movement across the bilayer, the formation of ordered lipid domains, coupling between the physical properties in each leaflet, and membrane protein conformation. Lipid domain formation stands out as one of the most important properties in which asymmetry is likely to be crucial. Lipid bilayers can exist in both liquidlike and solid/ordered-like states depending on lipid structure, and in lipid vesicles with a mixture of lipids highly ordered and disordered domains can coexist. However, until very recently, such studies only had been carried out in symmetric artificial membranes. Whether ordered domains (often called lipid rafts) and disordered lipid domains coexist in asymmetric cell membranes remains controversial partly because lipids favoring the formation of an ordered state are largely restricted to the leaflet facing the external environment. Studies using asymmetric vesicles have recently shown that each leaflet can influence the physical behavior of the other, i.e., that the domain forming properties in each leaflet tend to be coupled, with consequences highly dependent upon the details of lipid structure. Future studies investigating the dependence of coupling and properties upon the details of lipid composition should clarify the potential of natural membranes to form lipid domains. In addition, we recently extended the exchange method to living mammalian cells, using exchange to efficiently replace virtually the entire phospholipid and sphingolipid population of the plasma membrane outer leaflet with exogenous lipids without harming cells. This should allow detailed studies of the functional impact of lipid structure, asymmetry, domain organization, and interactions with membrane proteins in living cells.
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Affiliation(s)
- Erwin London
- Department of Biochemistry and Cell Biology and Department of Chemistry Stony Brook University, Stony Brook, New York 11794, United States
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33
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Hasan M, Moghal MMR, Saha SK, Yamazaki M. The role of membrane tension in the action of antimicrobial peptides and cell-penetrating peptides in biomembranes. Biophys Rev 2019; 11:431-448. [PMID: 31093936 DOI: 10.1007/s12551-019-00542-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 04/29/2019] [Indexed: 12/28/2022] Open
Abstract
For antimicrobial peptides (AMPs) with antimicrobial and bactericidal activities and cell-penetrating peptides (CPPs) with activity to permeate through plasma membrane, their interactions with lipid bilayer region in plasma membrane play important roles in these functions. However, the elementary processes and mechanisms of their functions have not been clear. The single giant unilamellar vesicle (GUV) method has revealed the details of elementary processes of interaction of some AMPs and CPPs with lipid vesicles. In this review, we summarize the mode of action of AMPs such as magainin 2 (Mag) and CPPs such as transportan 10 (TP10), revealed by the single GUV methods, and especially we focus on the role of membrane tension in actions of Mag and TP10 and the mechanisms of their actions. First, we explain the characteristics of the single GUV method briefly. Next, we summarize the recent view on the effect of tension on physical properties of lipid bilayers and describe the role of tension in actions of Mag and TP10. Some experimental results indicate that Mag-induced pore is a stretch-activated pore. The effect of packing of transbilayer asymmetric lipid on Mag-induced pore formation is described. On the other hand, entry of fluorescent dye, carboxyfluorescein (CF)-labeled TP10 (i.e., CF-TP10), into single GUVs without pore formation is affected by tension and high concentration of cholesterol. Pre-pore model for translocation of CF-TP10 across lipid bilayer is described. The experimental methods and their analysis described here are useful for investigation of functions of the other types of AMPs, CPPs, and proteins.
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Affiliation(s)
- Moynul Hasan
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka, 422-8529, Japan.,Department of Pharmacy, Jagannath University, Dhaka, 1100, Bangladesh
| | - Md Mizanur Rahman Moghal
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Samiron Kumar Saha
- 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, 836 Oya, Suruga-ku, Shizuoka, 422-8529, Japan. .,Department of Physics, Faculty of Science, Shizuoka University, Shizuoka, 422-8529, Japan.
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34
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Abstract
Freely suspended liposomes are widely used as model membranes for studying lipid-lipid and protein-lipid interactions. Liposomes prepared by conventional methods have chemically identical bilayer leaflets. By contrast, living cells actively maintain different lipid compositions in the two leaflets of the plasma membrane, resulting in asymmetric membrane properties that are critical for normal cell function. Here, we present a protocol for the preparation of unilamellar asymmetric phospholipid vesicles that better mimic biological membranes. Asymmetry is generated by methyl-β-cyclodextrin-catalyzed exchange of the outer leaflet lipids between vesicle pools of differing lipid composition. Lipid destined for the outer leaflet of the asymmetric vesicles is provided by heavy-donor multilamellar vesicles containing a dense sucrose core. Donor lipid is exchanged into extruded unilamellar acceptor vesicles that lack the sucrose core, facilitating the post-exchange separation of the donor and acceptor pools by centrifugation because of differences in vesicle size and density. We present two complementary assays allowing quantification of each leaflet's lipid composition: the overall lipid composition is determined by gas chromatography-mass spectrometry, whereas the lipid distribution between the two leaflets is determined by NMR, using the lanthanide shift reagent Pr3+. The preparation protocol and the chromatographic assay can be applied to any type of phospholipid bilayer, whereas the NMR assay is specific to lipids with choline-containing headgroups, such as phosphatidylcholine and sphingomyelin. In ~12 h, the protocol can produce a large yield of asymmetric vesicles (up to 20 mg) suitable for a wide range of biophysical studies.
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35
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Doktorova M, Heberle FA, Marquardt D, Rusinova R, Sanford RL, Peyear TA, Katsaras J, Feigenson GW, Weinstein H, Andersen OS. Gramicidin Increases Lipid Flip-Flop in Symmetric and Asymmetric Lipid Vesicles. Biophys J 2019; 116:860-873. [PMID: 30755300 PMCID: PMC6400823 DOI: 10.1016/j.bpj.2019.01.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 01/03/2019] [Accepted: 01/09/2019] [Indexed: 01/06/2023] Open
Abstract
Unlike most transmembrane proteins, phospholipids can migrate from one leaflet of the membrane to the other. Because this spontaneous lipid translocation (flip-flop) tends to be very slow, cells facilitate the process with enzymes that catalyze the transmembrane movement and thereby regulate the transbilayer lipid distribution. Nonenzymatic membrane-spanning proteins with unrelated primary functions have also been found to accelerate lipid flip-flop in a nonspecific manner and by various hypothesized mechanisms. Using deuterated phospholipids, we examined the acceleration of flip-flop by gramicidin channels, which have well-defined structures and known functions, features that make them ideal candidates for probing the protein-membrane interactions underlying lipid flip-flop. To study compositionally and isotopically asymmetric proteoliposomes containing gramicidin, we expanded a recently developed protocol for the preparation and characterization of lipid-only asymmetric vesicles. Channel incorporation, conformation, and function were examined with small angle x-ray scattering, circular dichroism, and a stopped-flow spectrofluorometric assay, respectively. As a measure of lipid scrambling, we used differential scanning calorimetry to monitor the effect of gramicidin on the melting transition temperatures of the two bilayer leaflets. The two calorimetric peaks of the individual leaflets merged into a single peak over time, suggestive of scrambling, and the effect of the channel on the transbilayer lipid distribution in both symmetric 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and asymmetric 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-phosphocholine vesicles was quantified from proton NMR measurements. Our results show that gramicidin increases lipid flip-flop in a complex, concentration-dependent manner. To determine the molecular mechanism of the process, we used molecular dynamics simulations and further computational analysis of the trajectories to estimate the extent of membrane deformation. Together, the experimental and computational approaches were found to constitute an effective means for studying the effects of transmembrane proteins on lipid distribution in both symmetric and asymmetric model membranes.
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Affiliation(s)
- Milka Doktorova
- Tri-Institutional PhD Program in Computational Biology and Medicine, Weill Cornell Medical College, New York, New York.
| | - Frederick A Heberle
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas; The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee
| | | | - Radda Rusinova
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York
| | - R Lea Sanford
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York
| | - Thasin A Peyear
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York
| | - John Katsaras
- Large Scale Structures Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Gerald W Feigenson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
| | - Harel Weinstein
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York; The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Greenberg Center, New York, New York
| | - Olaf S Andersen
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York
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36
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Leng X, Zhu F, Wassall SR. Vitamin E Has Reduced Affinity for a Polyunsaturated Phospholipid: An Umbrella Sampling Molecular Dynamics Simulations Study. J Phys Chem B 2018; 122:8351-8358. [PMID: 30111105 DOI: 10.1021/acs.jpcb.8b05016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vitamin E is an essential micronutrient. The primary function of this lipid-soluble antioxidant is to protect membrane phospholipids from oxidation. Whether vitamin E preferentially interacts with polyunsaturated phospholipids to optimize protection of the lipid species most vulnerable to oxidative attack has been an unanswered question for a long time. In this work, we compared the binding of α-tocopherol (αtoc), the form of vitamin E retained by the human body, in bilayers composed of polyunsaturated 1-stearoyl-2-docosahexaenoylphosphatidylcholine (SDPC, 18:0-22:6PC) and, as a control, monounsaturated 1-stearoyl-2-oleoylphosphatidylcholine (SOPC, 18:0-18:1PC) by umbrella sampling molecular dynamics simulations. From the potential of mean force as a function depth within the bilayer, we find that the binding energy of αtoc is less in SDPC (Δ Gbind = 16.7 ± 0.3 kcal/mol) than that in SOPC (Δ Gbind = 18.3 ± 0.4 kcal/mol). The lower value in SDPC is ascribed to the high disorder of polyunsaturated fatty acids that produces a less tightly packed arrangement. Deformation of the bilayer is observed during desorption, indicating that phosphatidylcholine (PC)-PC and αtoc-PC interactions contribute to the binding energy. Our results do not support the proposal that vitamin E interacts more favorably with polyunsaturated phospholipids.
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Affiliation(s)
- Xiaoling Leng
- Department of Physics , IUPUI , Indianapolis , Indiana 46202-3273 , United States
| | - Fangqiang Zhu
- Department of Physics , IUPUI , Indianapolis , Indiana 46202-3273 , United States
| | - Stephen R Wassall
- Department of Physics , IUPUI , Indianapolis , Indiana 46202-3273 , United States
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37
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Rokitskaya TI, Korshunova GA, Antonenko YN. Effect of Alkyl Chain Length on Translocation of Rhodamine B n-Alkyl Esters across Lipid Membranes. Biophys J 2018; 115:514-521. [PMID: 30031539 DOI: 10.1016/j.bpj.2018.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/27/2018] [Accepted: 07/02/2018] [Indexed: 01/03/2023] Open
Abstract
Voltage-dependent translocation of a series of cationic rhodamine B derivatives differing in n-alkyl chain length (ethyl, butyl, octyl, dodecyl, octadecyl) from one lipid monolayer to another was studied by measuring electrical current relaxation after a voltage jump on a planar bilayer phosphatidylcholine (PC) membrane. The rate of the translocation decreased in the following series of lipids: diphytanyl-PC > dioleyl-PC > diphytanoyl-PC > dierucoyl-PC. For all the lipids studied, the rate increased with lengthening of the hydrocarbon chain of the rhodamine derivatives, with the increase being most pronounced for the compounds having a short alkyl chain. The results could be well explained by involvement of molecule reorientations in the process of transmembrane flip-flop of the hydrophobic membrane-bound compounds. However, an impact of membrane dipole potential on the translocation rate could not be excluded, because the dipole potential could contribute to the energy barrier for translocation of the compounds located at different depths in the water-membrane interface. Based on the data obtained, a difference in the dipole potential of ester diphytanoyl-PC membranes with respect to ether diphytanyl-PC was estimated to be 108 mV, highlighting the contribution of a layer of oriented carbonyl groups of the lipids to the membrane dipole potential.
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Affiliation(s)
- Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
| | - Galina A Korshunova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
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38
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Hasan M, Saha SK, Yamazaki M. Effect of membrane tension on transbilayer movement of lipids. J Chem Phys 2018; 148:245101. [DOI: 10.1063/1.5035148] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Affiliation(s)
- Moynul Hasan
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Samiron Kumar Saha
- 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, 836 Oya, Suruga-ku, Shizuoka 422-8529, Japan
- Department of Physics, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan
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39
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Poursoroush A, Sperotto MM, Laradji M. Phase behavior of supported lipid bilayers: A systematic study by coarse-grained molecular dynamics simulations. J Chem Phys 2018; 146:154902. [PMID: 28433014 DOI: 10.1063/1.4981008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Solid-supported lipid bilayers are utilized by experimental scientists as models for biological membranes because of their stability. However, compared to free standing bilayers, their close proximity to the substrate may affect their phase behavior. As this is still poorly understood, and few computational studies have been performed on such systems thus far, here we present the results from a systematic study based on molecular dynamics simulations of an implicit-solvent model for solid-supported lipid bilayers with varying lipid-substrate interactions. The attractive interaction between the substrate and the lipid head groups that are closest to the substrate leads to an increased translocation of the lipids from the distal to the proximal bilayer-leaflet. This thereby leads to a transbilayer imbalance of the lipid density, with the lipid density of the proximal leaflet higher than that of the distal leaflet. Consequently, the order parameter of the proximal leaflet is found to be higher than that of the distal leaflet, the higher the strength of lipid interaction is, the stronger the effect. The proximal leaflet exhibits gel and fluid phases with an abrupt melting transition between the two phases. In contrast, below the melting temperature of the proximal leaflet, the distal leaflet is inhomogeneous with coexisting gel and fluid domains. The size of the fluid domains increases with increasing the strength of the lipid interaction. At low temperatures, the inhomogeneity of the distal leaflet is due to its reduced lipid density.
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Affiliation(s)
- Asma Poursoroush
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, USA
| | - Maria Maddalena Sperotto
- DTU Bioinformatics, Department of Bio and Health Informatics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Mohamed Laradji
- Department of Physics and Materials Science, The University of Memphis, Memphis, Tennessee 38152, USA
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40
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Hasan M, Karal MAS, Levadnyy V, Yamazaki M. Mechanism of Initial Stage of Pore Formation Induced by Antimicrobial Peptide Magainin 2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3349-3362. [PMID: 29446954 DOI: 10.1021/acs.langmuir.7b04219] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Antimicrobial peptide magainin 2 forms pores in lipid bilayers, a property that is considered the main cause of its bactericidal activity. Recent data suggest that tension or stretching of the inner monolayer plays an important role in magainin 2-induced pore formation in lipid bilayers. Here, to elucidate the mechanism of magainin 2-induced pore formation, we investigated the effect on pore formation of asymmetric lipid distribution in two monolayers. First, we developed a method to prepare giant unilamellar vesicles (GUVs) composed of dioleoylphosphatidylglycerol (DOPG), dioleoylphosphatidylcholine (DOPC), and lyso-PC (LPC) in the inner monolayer and of DOPG/DOPC in the outer monolayer. We consider that in these GUVs, the lipid packing in the inner monolayer was larger than that in the outer monolayer. Next, we investigated the interaction of magainin 2 with these GUVs with an asymmetric distribution of LPC using the single GUV method, and found that the rate constant of magainin 2-induced pore formation, kp, decreased with increasing LPC concentration in the inner monolayer. We constructed a quantitative model of magainin 2-induced pore formation, whereby the binding of magainin 2 to the outer monolayer of a GUV induces stretching of the inner monolayer, causing pore formation. A theoretical equation defining kp as a function of magainin 2 surface concentration, X, reasonably explains the experimental relationship between kp and X. This model quantitatively explains the effect on kp of the LPC concentration in the inner monolayer. On the basis of these results, we discuss the mechanism of the initial stage of magainin 2-induced pore formation.
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Affiliation(s)
- Moynul Hasan
- Integrated Bioscience Section, Graduate School of Science and Technology , Shizuoka University , Shizuoka 422-8529 , Japan
| | - Mohammad Abu Sayem Karal
- Integrated Bioscience Section, Graduate School of Science and Technology , Shizuoka University , Shizuoka 422-8529 , Japan
| | - Victor Levadnyy
- Integrated Bioscience Section, Graduate School of Science and Technology , Shizuoka University , Shizuoka 422-8529 , Japan
- Theoretical Problem Center of Physico-Chemical Pharmacology , Russian Academy of Sciences , Kosugina, 4 , 117977 Moscow , Russia
| | - 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 , 836 Oya , Suruga-ku, Shizuoka 422-8529 , Japan
- Department of Physics, Faculty of Science , Shizuoka University , Shizuoka 422-8529 , Japan
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41
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Coreta-Gomes FM, Vaz WLC, Moreno MJ. Effect of Acyl Chain Length on the Rate of Phospholipid Flip-Flop and Intermembrane Transfer. J Membr Biol 2017; 251:431-442. [PMID: 29264685 DOI: 10.1007/s00232-017-0009-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 12/13/2017] [Indexed: 11/25/2022]
Abstract
The rate at which phospholipids equilibrate between different membranes and between the non-polar environments in biological fluids is of high importance in the understanding of biomembrane diversity, as well as in the development of liposomes for drug delivery. In this work, we characterize the rate of insertion into and desorption from POPC bilayers for a homologous series of amphiphiles with the fluorescent NBD group attached to phosphoethanolamines of different acyl chain lengths, NBD-diC n -PE with n = 6, 8, 10, and 12. The rate of translocation between bilayer leaflets was also characterized, providing all the relevant parameters for their interaction with lipid bilayers. The results are complemented with data for NBD-diC14-PE obtained from literature (Abreu et al. Biophys J 87:353-365, 2004; Moreno et al. Biophys J 91:873-881, 2006). The rate of translocation between the POPC leaflets is not dependent on the length of the acyl chains, while this affects strongly the rate of desorption from the bilayer. Insertion in the POPC bilayer is not diffusion controlled showing a significant dependence on the acyl chain length and on temperature. The results obtained are compared with those previously reported for NBD-LysoC14-PE (Sampaio et al. Biophys J 88:4064-4071, 2005), and with the homologous series of single chain amphiphiles NBD-C n (Cardoso et al. J Phys Chem B 114:16337-16346, 2010; J Phys Chem B 115:10098-10108, 2011). This allows the establishment of important relations between the rate constants for interaction with the lipid bilayers and the structural properties of the amphiphiles, namely the total surface and the cross-section of their non-polar region.
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Affiliation(s)
- Filipe M Coreta-Gomes
- CQC-Biological Chemistry Group, Chemistry Department FCTUC, Largo D. Dinis, Rua Larga, 3004-535, Coimbra, Portugal
- QOPNA, Chemistry Department, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Winchil L C Vaz
- CEDOC, NOVA Medical School, Faculdadede Ciências Médicas, Universidade NOVA de Lisboa, 1169-056, Lisbon, Portugal
| | - Maria J Moreno
- CQC-Biological Chemistry Group, Chemistry Department FCTUC, Largo D. Dinis, Rua Larga, 3004-535, Coimbra, Portugal.
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42
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Breidigan JM, Krzyzanowski N, Liu Y, Porcar L, Perez-Salas U. Influence of the membrane environment on cholesterol transfer. J Lipid Res 2017; 58:2255-2263. [PMID: 29046341 PMCID: PMC5711489 DOI: 10.1194/jlr.m077909] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/09/2017] [Indexed: 01/28/2023] Open
Abstract
Cholesterol, an essential component in biological membranes, is highly unevenly distributed within the cell, with most localized in the plasma membrane while only a small fraction is found in the endoplasmic reticulum, where it is synthesized. Cellular membranes differ in lipid composition and protein content, and these differences can exist across their leaflets too. This thermodynamic landscape that cellular membranes impose on cholesterol is expected to modulate its transport. To uncover the role the membrane environment has on cholesterol inter- and intra-membrane movement, we used time-resolved small angle neutron scattering to study the passive movement of cholesterol between and within membranes with varying degrees of saturation content. We found that cholesterol moves systematically slower as the degree of saturation in the membranes increases, from a palmitoyl oleyl phosphotidylcholine membrane, which is unsaturated, to a dipalmitoylphosphatidylcholine (DPPC) membrane, which is fully saturated. Additionally, we found that the energetic barrier to move cholesterol in these phosphatidylcholine membranes is independent of their relative lipid composition and remains constant for both flip-flop and exchange at ∼100 kJ/mol. Further, by replacing DPPC with the saturated lipid palmitoylsphingomyelin, an abundant saturated lipid of the outer leaflet of the plasma membrane, we found the rates decreased by a factor of two. This finding is in stark contrast with recent molecular dynamic simulations that predict a dramatic slow-down of seven orders of magnitude for cholesterol flipping in membranes with a similar phosphocholine and SM lipid composition.
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Affiliation(s)
| | | | - Yangmingyue Liu
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607
| | - Lionel Porcar
- Large Scale Structures Group, Institut Laue-Langevin, F-38042 Grenoble CEDEX 9, France
| | - Ursula Perez-Salas
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607
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43
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Nakao H, Ikeda K, Ishihama Y, Nakano M. Membrane-Spanning Sequences in Endoplasmic Reticulum Proteins Promote Phospholipid Flip-Flop. Biophys J 2017; 110:2689-2697. [PMID: 27332127 DOI: 10.1016/j.bpj.2016.05.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/30/2016] [Accepted: 05/09/2016] [Indexed: 10/21/2022] Open
Abstract
The mechanism whereby phospholipids rapidly flip-flop in the endoplasmic reticulum (ER) membrane remains unknown. We previously demonstrated that the presence of a hydrophilic residue in the center of the model transmembrane peptide sequence effectively promoted phospholipid flip-flop and that hydrophilic residues composed 4.5% of the central regions of the membrane-spanning sequences of human ER membrane proteins predicted by SOSUI software. We hypothesized that ER proteins with hydrophilic residues might play a critical role in promoting flip-flop. Here, we evaluated the flip rate of fluorescently labeled lipids in vesicles containing each of the 11 synthetic peptides of membrane-spanning sequences, using a dithionite-quenching assay. Although the flippase activities of nine peptides were unexpectedly low, the peptides based on the EDEM1 and SPAST proteins showed enhanced flippase activity with three different fluorescently labeled lipids. The substitution of hydrophobic Ala with His or Arg in the central region of the EDEM1 or SPAST peptides, respectively, attenuated their ability to flip phospholipids. Interestingly, substituting Ala with Arg or His at a location outside of the central region of EDEM1 or SPAST, respectively, also affected the enhancement of flip-flop. These results indicated that both Arg and His are important for the ability of these two peptides to increase the flip rates. The EDEM1 peptide exhibited high activity at significantly low peptide concentrations, suggesting that the same side positioning of Arg and His in α-helix structure is critical for the flip-flop promotion and that the EDEM1 protein is a candidate flippase in the ER.
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Affiliation(s)
- Hiroyuki Nakao
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Keisuke Ikeda
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Yasushi Ishihama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Minoru Nakano
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
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44
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Marquardt D, Heberle FA, Miti T, Eicher B, London E, Katsaras J, Pabst G. 1H NMR Shows Slow Phospholipid Flip-Flop in Gel and Fluid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3731-3741. [PMID: 28106399 PMCID: PMC5397887 DOI: 10.1021/acs.langmuir.6b04485] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We measured the transbilayer diffusion of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in large unilamellar vesicles, in both the gel (Lβ') and fluid (Lα) phases. The choline resonance of headgroup-protiated DPPC exchanged into the outer leaflet of headgroup-deuterated DPPC-d13 vesicles was monitored using 1H NMR spectroscopy, coupled with the addition of a paramagnetic shift reagent. This allowed us to distinguish between the inner and outer bilayer leaflet of DPPC, to determine the flip-flop rate as a function of temperature. Flip-flop of fluid-phase DPPC exhibited Arrhenius kinetics, from which we determined an activation energy of 122 kJ mol-1. In gel-phase DPPC vesicles, flip-flop was not observed over the course of 250 h. Our findings are in contrast to previous studies of solid-supported bilayers, where the reported DPPC translocation rates are at least several orders of magnitude faster than those in vesicles at corresponding temperatures. We reconcile these differences by proposing a defect-mediated acceleration of lipid translocation in supported bilayers, where long-lived, submicron-sized holes resulting from incomplete surface coverage are the sites of rapid transbilayer movement.
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Affiliation(s)
- Drew Marquardt
- Institute
of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Graz 8010, Austria
- BioTechMed-Graz, Graz 8010, Austria
- E-mail: (D.M.)
| | - Frederick A. Heberle
- The Bredesen
Center and Department of Physics and Astronomy, University
of Tennessee, Knoxville, Tennessee 37996, United States
- Joint Institute for Biological Sciences, Biology and Soft
Matter Division, and Shull Wollan
Center—A Joint Institute for Neutron Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- E-mail: (F.A.H.)
| | - Tatiana Miti
- Department
of Physics, University of South Florida, Tampa, Florida 33620,United States
| | - Barbara Eicher
- Institute
of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Graz 8010, Austria
- BioTechMed-Graz, Graz 8010, Austria
| | - Erwin London
- Department
of Biochemistry and Cell Biology, Stony Brook, New York 11794, United States
| | - John Katsaras
- The Bredesen
Center and Department of Physics and Astronomy, University
of Tennessee, Knoxville, Tennessee 37996, United States
- Joint Institute for Biological Sciences, Biology and Soft
Matter Division, and Shull Wollan
Center—A Joint Institute for Neutron Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Georg Pabst
- Institute
of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Graz 8010, Austria
- BioTechMed-Graz, Graz 8010, Austria
- E-mail: (G.P.)
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45
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Escoffre JM, Derieppe M, Lammertink B, Bos C, Moonen C. Microbubble-Assisted Ultrasound-Induced Transient Phosphatidylserine Translocation. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:838-851. [PMID: 28109698 DOI: 10.1016/j.ultrasmedbio.2016.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 11/26/2016] [Accepted: 12/07/2016] [Indexed: 06/06/2023]
Abstract
Microbubble-assisted ultrasound (sonopermeabilization) results in reversible permeabilization of the plasma membrane of cells. This method is increasingly used in vivo because of its potential to deliver therapeutic molecules with limited cell damage. Nevertheless, the effects of sonopermeabilization on the plasma membrane remain not fully understood. We investigated the influence of sonopermeabilization on the transverse mobility of phospholipids, especially on phosphatidylserine (PS) externalization. We performed studies using optical imaging with Annexin V and FM1-43 probes to monitor PS externalization of rat glioma C6 cells. Sonopermeabilization induced transient membrane permeabilization, which is positively correlated with reversible PS externalization. This membrane disorganization was temporary and not associated with loss of cell viability. Sonopermeabilization did not induce PS externalization via activation of the scramblase. We hypothesize that acoustically induced membrane pores may provide a new pathway for PS migration between both membrane leaflets. During the membrane-resealing phase, PS asymmetry may be re-established by amino-phospholipid flippase activity and/or endocytosis, along with exocytosis processes.
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Affiliation(s)
| | - Marc Derieppe
- Imaging Division, UMC Utrecht, Utrecht, The Netherlands
| | | | - Clemens Bos
- Imaging Division, UMC Utrecht, Utrecht, The Netherlands
| | - Chrit Moonen
- Imaging Division, UMC Utrecht, Utrecht, The Netherlands
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46
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Schantz AB, Saboe PO, Sines IT, Lee HY, Bishop KJM, Maranas JK, Butler PD, Kumar M. PEE–PEO Block Copolymer Exchange Rate between Mixed Micelles Is Detergent and Temperature Activated. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b01973] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Allen B. Schantz
- Department
of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Patrick O. Saboe
- Department
of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ian T. Sines
- Department
of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Hee-Young Lee
- Department
of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Kyle J. M. Bishop
- Department
of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Janna K. Maranas
- Department
of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Paul D. Butler
- NIST
Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, United States
- Department
of Chemistry, University of Tennessee, Knoxville, Knoxville, Tennessee 37996-1600, United States
| | - Manish Kumar
- Department
of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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47
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Abstract
Our current view of cellular membranes centers on the fluid-mosaic model, which envisions the cellular membrane as a "liquidlike" bilayer of lipids, cholesterol, and proteins that freely diffuse in two dimensions. In stark contrast, the exchange of materials between the leaflets of a bilayer was presumed to be prohibited by the large enthalpic barrier associated with translocating hydrophilic materials, such as a charged lipid headgroup, through the hydrophobic membrane core. This static picture with regard to lipid translocation (or "flip-flop" as it is affectionately known) has been a long-held belief in the study of membrane dynamics. The current accepted membrane model invokes specific protein flippase (inward moving), floppase (outward moving), and scramblase (bidirectional) enzymes that assist in the movement of lipids between the leaflets of cellular membranes. The low rate of protein-free lipid flip-flop has also been a cornerstone of our understanding of the bilateral organization of cellular membrane components, specifically the asymmetric distribution of lipid species found in the luminal and extracellular leaflets of the plasma membrane of eukaryotic cells. Much of the previous work contributing to our current understanding of lipid flip-flop has utilized fluorescent- or spin-labeled lipids. However, there is growing evidence that these lipid probes do not accurately convey the dynamics and thermodynamics of native (unlabeled) lipid motion. This Account summarizes our research efforts directed toward developing a deep physical and chemical understanding of protein-free lipid flip-flop in phospholipid membrane models using sum-frequency vibrational spectroscopy (SFVS). Our use of SFVS enables the direct measurement of native lipid flip-flop in model membranes. In particular, we have explored the kinetic rates and activation thermodynamics of lipid translocation as a means of deciphering the underlying chemical and physical directors governing this process. By means of transition state theory, the contributions from enthalpy and entropy on the activation energy barrier to lipid flip-flop have been explored in detail for a variety of lipid species and membrane compositions. Specifically, the effect of lipid structure and packing and the inclusion of cholesterol and transmembrane peptides on the rates and thermodynamics of lipid translocation have been investigated in detail. It is our hope that these studies will provide a new perspective on lipid translocation in biological membranes and the role of lipid flip-flop in generating and maintaining cell membrane lipid asymmetry.
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Affiliation(s)
- John S. Allhusen
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - John C. Conboy
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
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48
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Xia Y, Charubin K, Marquardt D, Heberle FA, Katsaras J, Tian J, Cheng X, Liu Y, Nieh MP. Morphology-Induced Defects Enhance Lipid Transfer Rates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:9757-9764. [PMID: 27560711 DOI: 10.1021/acs.langmuir.6b02099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Molecular transfer between nanoparticles has been considered to have important implications regarding nanoparticle stability. Recently, the interparticle spontaneous lipid transfer rate constant for discoidal bicelles was found to be very different from spherical, unilamellar vesicles (ULVs). Here, we investigate the mechanism responsible for this discrepancy. Analysis of the data indicates that lipid transfer is entropically favorable, but enthalpically unfavorable with an activation energy that is independent of bicelle size and long- to short-chain lipid molar ratio. Moreover, molecular dynamics simulations reveal a lower lipid dissociation energy cost in the vicinity of interfaces ("defects") induced by the segregation of the long- and short-chain lipids in bicelles; these defects are not present in ULVs. Taken together, these results suggest that the enhanced lipid transfer observed in bicelles arises from interfacial defects as a result of the hydrophobic mismatch between the long- and short-chain lipid species. Finally, the observed lipid transfer rate is found to be independent of nanoparticle stability.
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Affiliation(s)
| | | | - Drew Marquardt
- Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz , Graz 8010, Austria
- Department of Physics, Brock University , St. Catharines, Ontario L2S 3A1, Canada
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49
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Intramitochondrial phospholipid trafficking. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:81-89. [PMID: 27542541 DOI: 10.1016/j.bbalip.2016.08.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/03/2016] [Accepted: 08/11/2016] [Indexed: 12/29/2022]
Abstract
Mitochondrial functions and architecture rely on a defined lipid composition of their outer and inner membranes, which are characterized by a high content of non-bilayer phospholipids such as cardiolipin (CL) and phosphatidylethanolamine (PE). Mitochondrial membrane lipids are synthesized in the endoplasmic reticulum (ER) or within mitochondria from ER-derived precursor lipids, are asymmetrically distributed within mitochondria and can relocate in response to cellular stress. Maintenance of lipid homeostasis thus requires multiple lipid transport processes to be orchestrated within mitochondria. Recent findings identified members of the Ups/PRELI family as specific lipid transfer proteins in mitochondria that shuttle phospholipids between mitochondrial membranes. They cooperate with membrane organizing proteins that preserve the spatial organization of mitochondrial membranes and the formation of membrane contact sites, unravelling an intimate crosstalk of membrane lipid transport and homeostasis with the structural organization of mitochondria. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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50
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Pownall HJ, Gotto AM. New Insights into the High-Density Lipoprotein Dilemma. Trends Endocrinol Metab 2016; 27:44-53. [PMID: 26673122 PMCID: PMC4707953 DOI: 10.1016/j.tem.2015.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 11/07/2015] [Accepted: 11/09/2015] [Indexed: 12/21/2022]
Abstract
Although high-density lipoprotein-cholesterol (HDL-C) concentration is a negative risk factor for atherosclerotic cardiovascular disease (CVD), efforts to reduce CVD risk by raising HDL-C have not been uniformly successful. Many studies have shown that alcohol consumption, that increases plasma HDL-C concentration, reduces CVD incidence. However, recent genetic studies in large populations have not only removed HDL-C from the causal link between plasma HDL-C concentration and reduced CVD risk, but also suggest that the association is weak. We propose here that the cardioprotective effects of alcohol are mediated by the interaction of its terminal metabolite, acetate, with the adipocyte free fatty acid receptor 2 (FFAR2), which elicits a profound antilipolytic effect that may increase insulin sensitivity without necessarily raising plasma HDL-C concentration.
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Affiliation(s)
- Henry J. Pownall
- Houston Methodist Research Institute and Weill Cornell Medical College, 6670 Bertner Avenue, Houston TX 77030
| | - Antonio M. Gotto
- Houston Methodist Research Institute and Weill Cornell Medical College, 1305 York Avenue, New York, NY, USA
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