51
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Nagle JF, Jennings N, Qin W, Yan D, Tristram-Nagle S, Heinrich F. Structure of the gel phase of diC22:1PC lipid bilayers determined by x-ray diffraction. Biophys J 2023; 122:1033-1042. [PMID: 36566351 PMCID: PMC10111270 DOI: 10.1016/j.bpj.2022.12.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/21/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022] Open
Abstract
High-resolution x-ray data are reported for the ordered phases of long-chain di-monounsaturated C22:1 phosphocholine lipid bilayers. Similar to PC lipids that have saturated chains, diC22:1PC has a subgel phase and a gel phase, but dissimilarly, we find no ripple phase. Our quantitative focus is on the structure of the gel phase. We have recorded 17 lamellar orders, indicating a very well-ordered structure. Fitting to a model provides the phases of the orders. The Fourier construction of the electron density profile has two well-defined headgroup peaks and a very sharp and deep methyl trough. The wide-angle scattering exhibits two Bragg rods that provide the area per molecule. They have an intensity pattern quite different than that of lipids with saturated chains. Models of chain packing indicate that ground state chain configurations are tilted primarily toward next nearest neighbors with an angle that is also consistent with the modeling of the electron density profile. Wide-angle modeling also indicates broken mirror symmetry between the monolayers. Our wide-angle results and our electron density profile together leads to the hypothesis that the sn-1 and sn-2 chains have equivalent penetration depths in contrast to the gel phase structure of lipids with saturated hydrocarbon chains.
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Affiliation(s)
- John F Nagle
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania.
| | - Nathaniel Jennings
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Weiheng Qin
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Daniel Yan
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | | | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania; Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland
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52
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Tamaian R, Porozov Y, Shityakov S. Exhaustive in silico design and screening of novel antipsychotic compounds with improved pharmacodynamics and blood-brain barrier permeation properties. J Biomol Struct Dyn 2023; 41:14849-14870. [PMID: 36927517 DOI: 10.1080/07391102.2023.2184179] [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] [Received: 09/15/2022] [Accepted: 02/18/2023] [Indexed: 03/18/2023]
Abstract
Antipsychotic drugs or neuroleptics are widely used in the treatment of psychosis as a manifestation of schizophrenia and bipolar disorder. However, their effectiveness largely depends on the blood-brain barrier (BBB) permeation (pharmacokinetics) and drug-receptor pharmacodynamics. Therefore, in this study, we developed and implemented the in silico pipeline to design novel compounds (n = 260) as leads using the standard drug scaffolds with improved PK/PD properties from the standard scaffolds. As a result, the best candidates (n = 3) were evaluated in molecular docking to interact with serotonin and dopamine receptors. Finally, haloperidol (HAL) derivative (1-(4-fluorophenyl)-4-(4-hydroxy-4-{4-[(2-phenyl-1,3-thiazol-4-yl)methyl]phenyl}piperidin-1-yl)butan-1-one) was identified as a "magic shotgun" lead compound with better affinity to the 5-HT2A, 5-HT1D, D2, D3, and 5-HT1B receptors than the control molecule. Additionally, this hit substance was predicted to possess similar BBB permeation properties and much lower toxicological profiles in comparison to HAL. Overall, the proposed rational drug design platform for novel antipsychotic drugs based on the BBB permeation and receptor binding might be an invaluable asset for a medicinal chemist or translational pharmacologist.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Radu Tamaian
- ICSI Analytics, National Research and Development Institute for Cryogenics and Isotopic Technologies - ICSI Rm. Vâlcea, Râmnicu Vâlcea, Romania
| | - Yuri Porozov
- Center of Bio- and Chemoinformatics, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Sergey Shityakov
- Laboratory of Chemoinformatics, Infochemistry Scientific Center, ITMO University, Saint-Petersburg, Russia
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53
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Lenz J, Larsen AH, Keller S, Luchini A. Effect of Cholesterol on the Structure and Composition of Glyco-DIBMA Lipid Particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:3569-3579. [PMID: 36854196 PMCID: PMC10018766 DOI: 10.1021/acs.langmuir.2c03019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 02/16/2023] [Indexed: 06/18/2023]
Abstract
Different amphiphilic co-polymers have been introduced to produce polymer-lipid particles with nanodisc structure composed of an inner lipid bilayer and polymer chains self-assembled as an outer belt. These particles can be used to stabilize membrane proteins in solution and enable their characterization by means of biophysical methods, including small-angle X-ray scattering (SAXS). Some of these co-polymers have also been used to directly extract membrane proteins together with their associated lipids from native membranes. Styrene/maleic acid and diisobutylene/maleic acid are among the most commonly used co-polymers for producing polymer-lipid particles, named SMALPs and DIBMALPs, respectively. Recently, a new co-polymer, named Glyco-DIBMA, was produced by partial amidation of DIBMA with the amino sugar N-methyl-d-glucosamine. Polymer-lipid particles produced with Glyco-DIBMA, named Glyco-DIBMALPs, exhibit improved structural properties and stability compared to those of SMALPs and DIBMALPs while retaining the capability of directly extracting membrane proteins from native membranes. Here, we characterize the structure and lipid composition of Glyco-DIBMALPs produced with either 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Glyco-DIBMALPs were also prepared with mixtures of either POPC or DMPC and cholesterol at different mole fractions. We estimated the lipid content in the Glyco-DIBMALPs and determined the particle structure and morphology by SAXS. We show that the Glyco-DIBMALPs are nanodisc-like particles whose size and shape depend on the polymer/lipid ratio. This is relevant for designing nanodisc particles with a tunable diameter according to the size of the membrane protein to be incorporated. We also report that the addition of >20 mol % cholesterol strongly perturbed the formation of Glyco-DIBMALPs. Altogether, we describe a detailed characterization of the Glyco-DIBMALPs, which provides relevant inputs for future application of these particles in the biophysical investigation of membrane proteins.
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Affiliation(s)
- Julia Lenz
- Molecular
Biophysics, Technische Universität
Kaiserslautern, Erwin-Schrödinger-Strasse
13, 67663 Kaiserslautern, Germany
| | | | - Sandro Keller
- Biophysics,
Institute of Molecular Biosciences (IMB), NAWI Graz, University of Graz, Humboldtstrasse 50/III, 8010 Graz, Austria
- Field
of Excellence BioHealth, University of Graz, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
| | - Alessandra Luchini
- European
Spallation Source - ERIC, Partikel Gatan, Lund 224
84, Sweden
- Department
of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
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54
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Woods B, Thompson KC, Szita N, Chen S, Milanesi L, Tomas S. Confinement effect on hydrolysis in small lipid vesicles. Chem Sci 2023; 14:2616-2623. [PMID: 36908967 PMCID: PMC9993861 DOI: 10.1039/d2sc05747f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/05/2023] [Indexed: 02/17/2023] Open
Abstract
In living organisms most chemical reactions take place within the confines of lipid-membrane bound compartments, while confinement within the bounds of a lipid membrane is thought to be a key step in abiogenesis. In previous work we demonstrated that confinement in the aqueous cavity of a lipid vesicle affords protection against hydrolysis, a phenomenon that we term here confinement effect (C e) and that we attributed to the interaction with the lipid membrane. Here, we show that both the size and the shape of the cavity of the vesicle modulate the C e. We link this observation to the packing of the lipid following changes in membrane curvature, and formulate a mathematical model that relates the C e to the radius of a spherical vesicle and the packing parameter of the lipids. These results suggest that the shape of the compartment where a molecule is located plays a major role in controlling the chemical reactivity of non-enzymatic reactions. Moreover, the mathematical treatment we propose offers a useful tool for the design of vesicles with predictable reaction rates of the confined molecules, e.g., drug delivery vesicles with confined prodrugs. The results also show that a crude form of signal transduction, devoid of complex biological machinery, can be achieved by any external stimuli that drastically changes the structure of the membrane, like the osmotic shocks used in the present work.
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Affiliation(s)
- Ben Woods
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London Malet Street London WC1E 7HX UK
| | - Katherine C Thompson
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London Malet Street London WC1E 7HX UK
| | - Nicolas Szita
- Department of Biochemical Engineering, University College London, Bernard Katz Building Gordon Street London WC1H 0AH UK
| | - Shu Chen
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London Malet Street London WC1E 7HX UK
| | - Lilia Milanesi
- Department of Chemistry, University of the Balearic Islands Ctra. de Valldemossa, Km 7.5 07122 Palma de Mallorca Spain
| | - Salvador Tomas
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London Malet Street London WC1E 7HX UK.,Department of Chemistry, University of the Balearic Islands Ctra. de Valldemossa, Km 7.5 07122 Palma de Mallorca Spain
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55
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Ruan J, Liu C, Song H, Zhong T, Quan P, Fang L. A skin pharmacokinetics study of permeation enhancers: The root cause of dynamic enhancement effect on in vivo drug permeation. Eur J Pharm Biopharm 2023; 184:170-180. [PMID: 36731755 DOI: 10.1016/j.ejpb.2023.01.022] [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] [Received: 11/14/2022] [Revised: 01/16/2023] [Accepted: 01/26/2023] [Indexed: 01/31/2023]
Abstract
Skin pharmacokinetics (SPK) of permeation enhancers can answer the question of why enhancement effects different at the kinetic level. Herein, SPK of permeation enhancers were classified into two categories, namely, lateral elimination (elimination to surrounding stratum corneum (SC)) and longitudinal elimination (elimination to deep epidermal (EP)). They were evaluated with a specific parameter for permeation enhancers, diffusion ratio (DRSC-EP), according to results of tissue-distribution test, molecular dynamic (MD) simulation, and confocal laser scanning microscopy (CLSM). The linear relationship between ke-enahcer and Δ Cmax-drug (R2 = 0.92), MRTenhancer and Δ Tmax-drug (R2 = 0.97), AUCt-enhancer and Δ AUCt-drug (R2 = 0.90) suggesting that SPK of permeation enhancers precisely controlled dynamic process of drug permeation in vivo. The molecular mechanisms of the dynamic effect of SPK process on drug transdermal behaviors were characterized by modulated-temperature differential scanning calorimetry (MTDSC), dielectric spectroscopy, small-angle X-ray scattering (SAXS), solid-state NMR. Permeation enhancers with high molecular weight (M.W.) and high polar surface area (P.S.A.) had good compatibility and strong interaction strength with SC, leading their lateral-elimination behavior, causing their low DRSC-EP and resulting in low ke-enhancer, long MRTenhancer, and large AUCt-enhancer. Consequently, skin barrier can be rapidly opened fast and to a great extent. In summary, compared with SPK of permeation enhancers with longitudinal elimination, SPK of permeation enhancers with lateral elimination can enable more sustainable and greater drug permeation. The information about SPK of permeation enhancers offered a criterion to estimate its permeation-enhancement effect on the drug and its subsequent application in transdermal formulations.
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Affiliation(s)
- Jiuheng Ruan
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Chao Liu
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Haoyuan Song
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Ting Zhong
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Peng Quan
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Liang Fang
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China.
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56
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Incorporation and localisation of alkanes in a protomembrane model by neutron diffraction. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184119. [PMID: 36638951 DOI: 10.1016/j.bbamem.2023.184119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/15/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023]
Abstract
Protomembranes at the origin of life were likely composed of short-chain lipids, readily available on the early Earth. Membranes formed by such lipids are less stable and more permeable under extreme conditions, so a novel membrane architecture was suggested to validate the accuracy of this assumption. The model membrane includes the presence of a layer of alkanes in the mid-plane of the protomembrane in between the two monolayer leaflets and lying perpendicular to the lipid acyl chains. Here, we investigated such a possibility experimentally for membranes formed by the short-chain phospholipid 1,2-didecanoyl-sn-glycero-3-phophocholine, including or not the alkanes eicosane, squalane or triacontane by means of neutron membrane diffraction and contrast variation. We found strong indications for incorporation of two of the three alkanes in the membrane mid-plane through the determination of neutron scattering length density profiles with hydrogenated vs deuterated alkanes and membrane swelling at various relative humidities indicating a slightly increased bilayer thickness when the alkanes are incorporated into the bilayers. The selectivity of the incorporation points out the role of the length of the n-alkanes with respect to the capacity of the membrane to incorporate them.
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57
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Lado-Touriño I, Cerpa-Naranjo A. Coarse-Grained Molecular Dynamics of pH-Sensitive Lipids. Int J Mol Sci 2023; 24:ijms24054632. [PMID: 36902063 PMCID: PMC10003205 DOI: 10.3390/ijms24054632] [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] [Received: 01/20/2023] [Revised: 02/20/2023] [Accepted: 02/25/2023] [Indexed: 03/06/2023] Open
Abstract
pH-sensitive lipids represent a class of lipids that can be protonated and destabilized in acidic environments, as they become positively charged in response to low-pH conditions. They can be incorporated into lipidic nanoparticles such as liposomes, which are able to change their properties and allow specific drug delivery at the acidic conditions encountered in some pathological microenvironments. In this work, we used coarse-grained molecular-dynamic simulations to study the stability of neutral and charged lipid bilayers containing POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and various kinds of ISUCA ((F)2-(imidazol-1-yl)succinic acid)-derived lipids, which can act as pH-sensitive molecules. In order to explore such systems, we used a MARTINI-derived forcefield, previously parameterized using all-atom simulation results. We calculated the average area per lipid, the second-rank order parameter and the lipid diffusion coefficient of both lipid bilayers made of pure components and mixtures of lipids in different proportions, under neutral or acidic conditions. The results show that the use of ISUCA-derived lipids disturbs the lipid bilayer structure, with the effect being particularly marked under acidic conditions. Although more-in depth studies on these systems must be carried out, these initial results are encouraging and the lipids designed in this research could be a good basis for developing new pH-sensitive liposomes.
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58
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Ivanova N, Chamati H. The Effect of Cholesterol in SOPC Lipid Bilayers at Low Temperatures. MEMBRANES 2023; 13:275. [PMID: 36984662 PMCID: PMC10058253 DOI: 10.3390/membranes13030275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 02/21/2023] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
We study the behavior of lipid bilayers composed of SOPC (1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine) with different concentrations of cholesterol, ranging from 10 mol% to 50 mol% at 273 K. To this end, we carry out extensive atomistic molecular dynamic simulations with the aid of the Slipid force field aiming at computing basic bilayer parameters, as well as thermodynamic properties and structural characteristics. The obtained results are compared to available relevant experimental data and the outcome of atomistic simulations performed on bilayers composed of analogous phospholipids. Our results show a good quantitative, as well as qualitative, agreement with the main trends associated with the concentration increase in cholesterol. Moreover, it comes out that a change in the behavior of the bilayer is brought about at a concentration of about 30 mol% cholesterol. At this very concentration, some of the bilayer properties are found to exhibit a saturation and a significant long-range ordering of the lipid molecules in the membrane shows up.
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Affiliation(s)
- Nikoleta Ivanova
- Department of Physical Chemistry, University of Chemical Technology and Metallurgy, 8 Kliment Ohridski Blvd., 1756 Sofia, Bulgaria
- Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
| | - Hassan Chamati
- Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
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59
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Sengottiyan S, Mikolajczyk A, Puzyn T. How Does the Study MD of pH-Dependent Exposure of Nanoparticles Affect Cellular Uptake of Anticancer Drugs? Int J Mol Sci 2023; 24:ijms24043479. [PMID: 36834890 PMCID: PMC9958846 DOI: 10.3390/ijms24043479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 02/12/2023] Open
Abstract
The lack of knowledge about the uptake of NPs by biological cells poses a significant problem for drug delivery. For this reason, designing an appropriate model is the main challenge for modelers. To address this problem, molecular modeling studies that can describe the mechanism of cellular uptake of drug-loaded nanoparticles have been conducted in recent decades. In this context, we developed three different models for the amphipathic nature of drug-loaded nanoparticles (MTX-SS-γ-PGA), whose cellular uptake mechanism was predicted by molecular dynamics studies. Many factors affect nanoparticle uptake, including nanoparticle physicochemical properties, protein-particle interactions, and subsequent agglomeration, diffusion, and sedimentation. Therefore, the scientific community needs to understand how these factors can be controlled and the NP uptake of nanoparticles. Based on these considerations, in this study, we investigated for the first time the effects of the selected physicochemical properties of the anticancer drug methotrexate (MTX) grafted with hydrophilic-γ-polyglutamic acid (MTX-SS-γ-PGA) on its cellular uptake at different pH values. To answer this question, we developed three theoretical models describing drug-loaded nanoparticles (MTX-SS-γ-PGA) at three different pH values, such as (1) pH 7.0 (the so-called neutral pH model), (2) pH 6.4 (the so-called tumor pH model), and (3) pH 2.0 (the so-called stomach pH model). Exceptionally, the electron density profile shows that the tumor model interacts more strongly with the head groups of the lipid bilayer than the other models due to charge fluctuations. Hydrogen bonding and RDF analyses provide information about the solution of the NPs with water and their interaction with the lipid bilayer. Finally, dipole moment and HOMO-LUMO analysis showed the free energy of the solution in the water phase and chemical reactivity, which are particularly useful for determining the cellular uptake of the NPs. The proposed study provides fundamental insights into molecular dynamics (MD) that will allow researchers to determine the influence of pH, structure, charge, and energetics of NPs on the cellular uptake of anticancer drugs. We believe that our current study will be useful in developing a new model for drug delivery to cancer cells with a much more efficient and less time-consuming model.
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60
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Huang Y, Karsai A, Sambre PD, Su WC, Faller R, Parikh AN, Liu GY. Production of Lipid Constructs by Design via Three-Dimensional Nanoprinting. MICROMACHINES 2023; 14:372. [PMID: 36838072 PMCID: PMC9963025 DOI: 10.3390/mi14020372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Revised: 01/25/2023] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
Atomic force microscopy (AFM) in conjunction with microfluidic delivery was utilized to produce three-dimensional (3D) lipid structures following a custom design. While AFM is well-known for its spatial precision in imaging and 2D nanolithography, the development of AFM-based nanotechnology into 3D nanoprinting requires overcoming the technical challenges of controlling material delivery and interlayer registry. This work demonstrates the concept of 3D nanoprinting of amphiphilic molecules such as 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Various formulations of POPC solutions were tested to achieve point, line, and layer-by-layer material delivery. The produced structures include nanometer-thick disks, long linear spherical caps, stacking grids, and organizational chiral architectures. The POPC molecules formed stacking bilayers in these constructions, as revealed by high-resolution structural characterizations. The 3D printing reached nanometer spatial precision over a range of 0.5 mm. The outcomes reveal the promising potential of our designed technology and methodology in the production of 3D structures from nanometer to continuum, opening opportunities in biomaterial sciences and engineering, such as in the production of 3D nanodevices, chiral nanosensors, and scaffolds for tissue engineering and regeneration.
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Affiliation(s)
- Yuqi Huang
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Arpad Karsai
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Pallavi D. Sambre
- Department of Materials Science and Engineering, University of California, Davis, CA 95616, USA
| | - Wan-Chih Su
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
| | - Roland Faller
- Department of Chemical Engineering, University of California, Davis, CA 95616, USA
| | - Atul N. Parikh
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
| | - Gang-yu Liu
- Department of Chemistry, University of California, Davis, CA 95616, USA
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61
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Zabala-Ferrera O, Liu P, Beltramo PJ. Determining the Bending Rigidity of Free-Standing Planar Phospholipid Bilayers. MEMBRANES 2023; 13:129. [PMID: 36837632 PMCID: PMC9959114 DOI: 10.3390/membranes13020129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/14/2023] [Accepted: 01/17/2023] [Indexed: 06/18/2023]
Abstract
We describe a method to determine membrane bending rigidity from capacitance measurements on large area, free-standing, planar, biomembranes. The bending rigidity of lipid membranes is an important biological mechanical property that is commonly optically measured in vesicles, but difficult to quantify in a planar, unsupported system. To accomplish this, we simultaneously image and apply an electric potential to free-standing, millimeter area, planar lipid bilayers composed of DOPC and DOPG phospholipids to measure the membrane Young's (elasticity) modulus. The bilayer is then modeled as two adjacent thin elastic films to calculate bending rigidity from the electromechanical response of the membrane to the applied field. Using DOPC, we show that bending rigidities determined by this approach are in good agreement with the existing work using neutron spin echo on vesicles, atomic force spectroscopy on supported lipid bilayers, and micropipette aspiration of giant unilamellar vesicles. We study the effect of asymmetric calcium concentration on symmetric DOPC and DOPG membranes and quantify the resulting changes in bending rigidity. This platform offers the ability to create planar bilayers of controlled lipid composition and aqueous ionic environment, with the ability to asymmetrically alter both. We aim to leverage this high degree of compositional and environmental control, along with the capacity to measure physical properties, in the study of various biological processes in the future.
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62
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Kurki M, Poso A, Bartos P, Miettinen MS. Structure of POPC Lipid Bilayers in OPLS3e Force Field. J Chem Inf Model 2022; 62:6462-6474. [PMID: 36044537 PMCID: PMC9795559 DOI: 10.1021/acs.jcim.2c00395] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
It is crucial for molecular dynamics simulations of biomembranes that the force field parameters give a realistic model of the membrane behavior. In this study, we examined the OPLS3e force field for the carbon-hydrogen order parameters SCH of POPC (1-palmitoyl-2-oleoylphosphatidylcholine) lipid bilayers at varying hydration conditions and ion concentrations. The results show that OPLS3e behaves similarly to the CHARMM36 force field and relatively accurately follows the experimentally measured SCH for the lipid headgroup, the glycerol backbone, and the acyl tails. Thus, OPLS3e is a good choice for POPC bilayer simulations under many biologically relevant conditions. The exception are systems with an abundancy of ions, as similarly to most other force fields OPLS3e strongly overestimates the membrane-binding of cations, especially Ca2+. This leads to undesirable positive charge of the membrane surface and drastically lowers the concentration of Ca2+ in the surrounding solvent, which might cause issues in systems sensitive to correct charge distribution profiles across the membrane.
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Affiliation(s)
- Milla Kurki
- School
of Pharmacy, University of Eastern Finland, Kuopio Campus, Yliopistonranta 1
C, P.O. Box 1627, 70211 Kuopio, Finland
| | - Antti Poso
- School
of Pharmacy, University of Eastern Finland, Kuopio Campus, Yliopistonranta 1
C, P.O. Box 1627, 70211 Kuopio, Finland
| | - Piia Bartos
- School
of Pharmacy, University of Eastern Finland, Kuopio Campus, Yliopistonranta 1
C, P.O. Box 1627, 70211 Kuopio, Finland,
| | - Markus S. Miettinen
- Department
of Chemistry, University of Bergen, 5007 Bergen, Norway,Computational
Biology Unit, Department of Informatics, University of Bergen, 5007 Bergen, Norway
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63
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Avalos-Padilla Y, Georgiev VN, Ewins E, Robinson T, Orozco E, Lipowsky R, Dimova R. Stepwise remodeling and subcompartment formation in individual vesicles by three ESCRT-III proteins. iScience 2022; 26:105765. [PMID: 36590172 PMCID: PMC9800321 DOI: 10.1016/j.isci.2022.105765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/21/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
The endosomal sorting complex required for transport (ESCRT) is a multi-protein machinery involved in several membrane remodeling processes. Different approaches have been used to resolve how ESCRT proteins scission membranes. However, the underlying mechanisms generating membrane deformations are still a matter of debate. Here, giant unilamellar vesicles, microfluidic technology, and micropipette aspiration are combined to continuously follow the ESCRT-III-mediated membrane remodeling on the single-vesicle level for the first time. With this approach, we identify different mechanisms by which a minimal set of three ESCRT-III proteins from Entamoeba histolytica reshape the membrane. These proteins modulate the membrane stiffness and spontaneous curvature to regulate bud size and generate intraluminal vesicles even in the absence of ATP. We demonstrate that the bud stability depends on the protein concentration and membrane tension. The approaches introduced here should open the road to diverse applications in synthetic biology for establishing artificial cells with several membrane compartments.
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Affiliation(s)
- Yunuen Avalos-Padilla
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476 Potsdam, Germany,Nanomalaria Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, ES-08028 Barcelona, Spain,Barcelona Institute for Global Health (ISGlobal, Hospital Clínic-Universitat de Barcelona), Rosselló 149-153, ES-08036 Barcelona, Spain
| | - Vasil N. Georgiev
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476 Potsdam, Germany
| | - Eleanor Ewins
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476 Potsdam, Germany
| | - Tom Robinson
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476 Potsdam, Germany
| | - Esther Orozco
- Departamento de Infectómica y Patogénesis Molecular, CINVESTAV IPN, 07360 Ciudad de México, México
| | - Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476 Potsdam, Germany
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476 Potsdam, Germany,Corresponding author
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64
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Di Micco S, Lauro G, Bifulco G. Extensive Molecular Dynamics Simulations Disclosed the Stability of mPGES-1 Enzyme and the Structural Role of Glutathione (GSH) Cofactor. Mol Inform 2022; 41:e2200140. [PMID: 36075865 PMCID: PMC10078397 DOI: 10.1002/minf.202200140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 09/08/2022] [Indexed: 01/05/2023]
Abstract
A deep in silico investigation of various microsomal prostaglandin E2 synthase-1 (mPGES-1) protein systems is here reported using molecular dynamics (MD) simulations. Firstly, eight different proteins models (Models A-H) were built, starting from the active enzyme trimer system (Model A), namely that bound to three glutathione (GSH) cofactor molecules, and then gradually removing the GSHs (Models B-H), simulating each of them for 100 ns in explicit solvent. The analysis of the obtained data disclosed the structural role of GSH in the chemical architecture of mPGES-1 enzyme, thus suggesting the unlikely displacement of this cofactor, in accordance with experimentally determined protein structures co-complexed with small molecule inhibitors. Afterwards, Model A was submitted to microsecond-scale molecular dynamics simulation (total simulation time=10 μs), in order to shed light about the dynamical behaviour of this enzyme at atomic level and to obtain further structural features and protein function information. We confirmed the structural stability of the enzyme machinery, observing a conformational rigidity of the protein, with a backbone RMSD of ∼3 Å along the simulation time, and highlighting the strong active contribution of GSH molecules due to their active role in packing the protein chains through a tight binding at monomer interfaces. Furthermore, the focused analysis on R73 residue disclosed its role in solvent exchange events, probably excluding its function as route for GSH to enter towards the endoplasmic reticulum membrane, in line with the recently reported function of cap domain residues F44-D66 as gatekeeper for GSH entrance into catalytic site.
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Affiliation(s)
- Simone Di Micco
- European Biomedical Research Institute of Salerno (EBRIS), via Salvatore De Renzi 50, 84125, Salerno, Italy
| | - Gianluigi Lauro
- Dipartimento di Farmacia, University degli Studi di Salerno, via Giovanni Paolo II 132, 84084, Fisciano (SA), Italy
| | - Giuseppe Bifulco
- Dipartimento di Farmacia, University degli Studi di Salerno, via Giovanni Paolo II 132, 84084, Fisciano (SA), Italy
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65
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Joseph A, Wagner AM, Garay-Sarmiento M, Aleksanyan M, Haraszti T, Söder D, Georgiev VN, Dimova R, Percec V, Rodriguez-Emmenegger C. Zwitterionic Dendrimersomes: A Closer Xenobiotic Mimic of Cell Membranes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2206288. [PMID: 36134536 DOI: 10.1002/adma.202206288] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/07/2022] [Indexed: 06/16/2023]
Abstract
Building functional mimics of cell membranes is an important task toward the development of synthetic cells. So far, lipid and amphiphilic block copolymers are the most widely used amphiphiles with the bilayers by the former lacking stability while membranes by the latter are typically characterized by very slow dynamics. Herein, a new type of Janus dendrimer containing a zwitterionic phosphocholine hydrophilic headgroup (JDPC ) and a 3,5-substituted dihydrobenzoate-based hydrophobic dendron is introduced. JDPC self-assembles in water into zwitterionic dendrimersomes (z-DSs) that faithfully recapitulate the cell membrane in thickness, flexibility, and fluidity, while being resilient to harsh conditions and displaying faster pore closing dynamics in the event of membrane rupture. This enables the fabrication of hybrid DSs with components of natural membranes, including pore-forming peptides, structure-directing lipids, and glycans to create raft-like domains or onion vesicles. Moreover, z-DSs can be used to create active synthetic cells with life-like features that mimic vesicle fusion and motility as well as environmental sensing. Despite their fully synthetic nature, z-DSs are minimal cell mimics that can integrate and interact with living matter with the programmability to imitate life-like features and beyond.
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Affiliation(s)
- Anton Joseph
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Anna M Wagner
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Manuela Garay-Sarmiento
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074, Aachen, Germany
- Chair of Biotechnology, RWTH Aachen University, Worringerweg 3, 52074, Aachen, Germany
| | - Mina Aleksanyan
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476, Potsdam, Germany
| | - Tamás Haraszti
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Dominik Söder
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Vasil N Georgiev
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476, Potsdam, Germany
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14476, Potsdam, Germany
| | - Virgil Percec
- Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104323, USA
| | - Cesar Rodriguez-Emmenegger
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074, Aachen, Germany
- Bioinspired Interactive Materials and Protocellular Systems, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer de Baldiri Reixac 10-12, 08028, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08028, Barcelona, Spain
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66
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Torralba J, de la Arada I, Partida-Hanon A, Rujas E, Arribas M, Insausti S, Valotteau C, Valle J, Andreu D, Caaveiro JMM, Jiménez MA, Apellániz B, Redondo-Morata L, Nieva JL. Molecular recognition of a membrane-anchored HIV-1 pan-neutralizing epitope. Commun Biol 2022; 5:1265. [DOI: 10.1038/s42003-022-04219-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/03/2022] [Indexed: 11/19/2022] Open
Abstract
AbstractAntibodies against the carboxy-terminal section of the membrane-proximal external region (C-MPER) of the HIV-1 envelope glycoprotein (Env) are considered as nearly pan-neutralizing. Development of vaccines capable of producing analogous broadly neutralizing antibodies requires deep understanding of the mechanism that underlies C-MPER recognition in membranes. Here, we use the archetypic 10E8 antibody and a variety of biophysical techniques including single-molecule approaches to study the molecular recognition of C-MPER in membrane mimetics. In contrast to the assumption that an interfacial MPER helix embodies the entire C-MPER epitope recognized by 10E8, our data indicate that transmembrane domain (TMD) residues contribute to binding affinity and specificity. Moreover, anchoring to membrane the helical C-MPER epitope through the TMD augments antibody binding affinity and relieves the effects exerted by the interfacial MPER helix on the mechanical stability of the lipid bilayer. These observations support that addition of TMD residues may result in more efficient and stable anti-MPER vaccines.
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67
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Gul G, Faller R, Ileri-Ercan N. Polystyrene-modified carbon nanotubes: Promising carriers in targeted drug delivery. Biophys J 2022; 121:4271-4279. [PMID: 36230001 PMCID: PMC9703093 DOI: 10.1016/j.bpj.2022.10.014] [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] [Received: 05/21/2022] [Revised: 08/28/2022] [Accepted: 10/11/2022] [Indexed: 12/14/2022] Open
Abstract
To design drug-delivery agents for therapeutic and diagnostic applications, understanding the mechanisms by which covalently functionalized carbon nanotubes penetrate and interact with cell membranes is of great importance. Here, we report all-atom molecular dynamics results from polystyrene and carboxyl-terminated polystyrene-modified carbon nanotubes and show their translocation behavior across a model lipid bilayer together with their potential to deliver a molecule of the drug ibuprofen into the cell. Our results indicate that functionalized carbon nanotubes are internalized by the membrane in hundreds of nanoseconds and that drug loading increases the internalization speed further. Both loaded and unloaded tubes cross the closest leaflet of the bilayer by nonendocytic pathways, and for the times studied, the drug molecule remains trapped inside the pristine tube while remaining attached at the end of polystyrene-modified tube. On the other hand, carboxyl-terminated polystyrene functionalization allows the drug to be completely released into the lower leaflet of the bilayer without imposing damage to the membrane. This study shows that polystyrene functionalization is a promising alternative and facilitates drug delivery as a benchmark case.
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Affiliation(s)
- Gulsah Gul
- Department of Chemical Engineering, Bogazici University, Bebek, Istanbul, Turkey; Department of Chemical Engineering, University of California, Davis, Davis, California
| | - Roland Faller
- Department of Chemical Engineering, University of California, Davis, Davis, California
| | - Nazar Ileri-Ercan
- Department of Chemical Engineering, Bogazici University, Bebek, Istanbul, Turkey.
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68
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Hasanzade Z, Raissi H, Hashemzadeh H. Molecular Mechanism of Drug Transport and Release through Zeolitic imidazole framework nanospheres for Versatile Drug Delivery Applications. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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69
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Molugu TR, Thurmond RL, Alam TM, Trouard TP, Brown MF. Phospholipid headgroups govern area per lipid and emergent elastic properties of bilayers. Biophys J 2022; 121:4205-4220. [PMID: 36088534 PMCID: PMC9674990 DOI: 10.1016/j.bpj.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 08/10/2022] [Accepted: 09/06/2022] [Indexed: 11/24/2022] Open
Abstract
Phospholipid bilayers are liquid-crystalline materials whose intermolecular interactions at mesoscopic length scales have key roles in the emergence of membrane physical properties. Here we investigated the combined effects of phospholipid polar headgroups and acyl chains on biophysical functions of membranes with solid-state 2H NMR spectroscopy. We compared the structural and dynamic properties of phosphatidylethanolamine and phosphatidylcholine with perdeuterated acyl chains in the solid-ordered (so) and liquid-disordered (ld) phases. Our analysis of spectral lineshapes of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE-d62) and 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine (DPPC-d62) in the so (gel) phase indicated an all-trans rotating chain structure for both lipids. Greater segmental order parameters (SCD) were observed in the ld (liquid-crystalline) phase for DPPE-d62 than for DPPC-d62 membranes, while their mixtures had intermediate values irrespective of the deuterated lipid type. Our results suggest the SCD profiles of the acyl chains are governed by methylation of the headgroups and are averaged over the entire system. Variations in the acyl chain molecular dynamics were further investigated by spin-lattice (R1Z) and quadrupolar-order relaxation (R1Q) measurements. The two acyl-perdeuterated lipids showed distinct differences in relaxation behavior as a function of the order parameter. The R1Z rates had a square-law dependence on SCD, implying collective mesoscopic dynamics, with a higher bending rigidity for DPPE-d62 than for DPPC-d62 lipids. Remodeling of lipid average and dynamic properties by methylation of the headgroups thus provides a mechanism to control the actions of peptides and proteins in biomembranes.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | | | - Todd M Alam
- Department of Organic Materials Science, Sandia National Laboratories, Albuquerque, New Mexico
| | - Theodore P Trouard
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
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70
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Heller WT. Small-Angle Neutron Scattering for Studying Lipid Bilayer Membranes. Biomolecules 2022; 12:1591. [PMID: 36358941 PMCID: PMC9687511 DOI: 10.3390/biom12111591] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/18/2022] [Accepted: 10/26/2022] [Indexed: 09/23/2023] Open
Abstract
Small-angle neutron scattering (SANS) is a powerful tool for studying biological membranes and model lipid bilayer membranes. The length scales probed by SANS, being from 1 nm to over 100 nm, are well-matched to the relevant length scales of the bilayer, particularly when it is in the form of a vesicle. However, it is the ability of SANS to differentiate between isotopes of hydrogen as well as the availability of deuterium labeled lipids that truly enable SANS to reveal details of membranes that are not accessible with the use of other techniques, such as small-angle X-ray scattering. In this work, an overview of the use of SANS for studying unilamellar lipid bilayer vesicles is presented. The technique is briefly presented, and the power of selective deuteration and contrast variation methods is discussed. Approaches to modeling SANS data from unilamellar lipid bilayer vesicles are presented. Finally, recent examples are discussed. While the emphasis is on studies of unilamellar vesicles, examples of the use of SANS to study intact cells are also presented.
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Affiliation(s)
- William T Heller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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71
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Abstract
Multiple membrane-shaping and remodeling processes are associated with tetraspanin proteins by yet unknown mechanisms. Tetraspanins constitute a family of proteins with four transmembrane domains present in every cell type. Prominent examples are tetraspanin4 and CD9, which are required for the fundamental cellular processes of migrasome formation and fertilization, respectively. These proteins are enriched in curved membrane structures, such as cellular retraction fibers and oocyte microvilli. The factors driving this enrichment are, however, unknown. Here, we revealed that tetraspanin4 and CD9 are curvature sensors with a preference for positive membrane curvature. To this end, we used a biomimetic system emulating membranes of cell retraction fibers and oocyte microvilli by membrane tubes pulled out of giant plasma membrane vesicles with controllable membrane tension and curvature. We developed a simple thermodynamic model for the partitioning of curvature sensors between flat and tubular membranes, which allowed us to estimate the individual intrinsic curvatures of the two proteins. Overall, our findings illuminate the process of migrasome formation and oocyte microvilli shaping and provide insight into the role of tetraspanin proteins in membrane remodeling processes.
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72
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Himbert S, Rheinstädter MC. Structural and mechanical properties of the red blood cell's cytoplasmic membrane seen through the lens of biophysics. Front Physiol 2022; 13:953257. [PMID: 36171967 PMCID: PMC9510598 DOI: 10.3389/fphys.2022.953257] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 08/15/2022] [Indexed: 11/27/2022] Open
Abstract
Red blood cells (RBCs) are the most abundant cell type in the human body and critical suppliers of oxygen. The cells are characterized by a simple structure with no internal organelles. Their two-layered outer shell is composed of a cytoplasmic membrane (RBC cm ) tethered to a spectrin cytoskeleton allowing the cell to be both flexible yet resistant against shear stress. These mechanical properties are intrinsically linked to the molecular composition and organization of their shell. The cytoplasmic membrane is expected to dominate the elastic behavior on small, nanometer length scales, which are most relevant for cellular processes that take place between the fibrils of the cytoskeleton. Several pathologies have been linked to structural and compositional changes within the RBC cm and the cell's mechanical properties. We review current findings in terms of RBC lipidomics, lipid organization and elastic properties with a focus on biophysical techniques, such as X-ray and neutron scattering, and Molecular Dynamics simulations, and their biological relevance. In our current understanding, the RBC cm 's structure is patchy, with nanometer sized liquid ordered and disordered lipid, and peptide domains. At the same time, it is surprisingly soft, with bending rigidities κ of 2-4 kBT. This is in strong contrast to the current belief that a high concentration of cholesterol results in stiff membranes. This extreme softness is likely the result of an interaction between polyunsaturated lipids and cholesterol, which may also occur in other biological membranes. There is strong evidence in the literature that there is no length scale dependence of κ of whole RBCs.
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Affiliation(s)
- Sebastian Himbert
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
- Origins Institute, McMaster University, Hamilton, ON, Canada
| | - Maikel C. Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
- Origins Institute, McMaster University, Hamilton, ON, Canada
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73
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Membranolytic Mechanism of Amphiphilic Antimicrobial β-Stranded [KL]n Peptides. Biomedicines 2022; 10:biomedicines10092071. [PMID: 36140173 PMCID: PMC9495826 DOI: 10.3390/biomedicines10092071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/19/2022] [Accepted: 08/21/2022] [Indexed: 11/17/2022] Open
Abstract
Amphipathic peptides can act as antibiotics due to membrane permeabilization. KL peptides with the repetitive sequence [Lys-Leu]n-NH2 form amphipathic β-strands in the presence of lipid bilayers. As they are known to kill bacteria in a peculiar length-dependent manner, we suggest here several different functional models, all of which seem plausible, including a carpet mechanism, a β-barrel pore, a toroidal wormhole, and a β-helix. To resolve their genuine mechanism, the activity of KL peptides with lengths from 6–26 amino acids (plus some inverted LK analogues) was systematically tested against bacteria and erythrocytes. Vesicle leakage assays served to correlate bilayer thickness and peptide length and to examine the role of membrane curvature and putative pore diameter. KL peptides with 10–12 amino acids showed the best therapeutic potential, i.e., high antimicrobial activity and low hemolytic side effects. Mechanistically, this particular window of an optimum β-strand length around 4 nm (11 amino acids × 3.7 Å) would match the typical thickness of a lipid bilayer, implying the formation of a transmembrane pore. Solid-state 15N- and 19F-NMR structure analysis, however, showed that the KL backbone lies flat on the membrane surface under all conditions. We can thus refute any of the pore models and conclude that the KL peptides rather disrupt membranes by a carpet mechanism. The intriguing length-dependent optimum in activity can be fully explained by two counteracting effects, i.e., membrane binding versus amyloid formation. Very short KL peptides are inactive, because they are unable to bind to the lipid bilayer as flexible β-strands, whereas very long peptides are inactive due to vigorous pre-aggregation into β-sheets in solution.
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74
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Hryc J, Szczelina R, Markiewicz M, Pasenkiewicz-Gierula M. Lipid/water interface of galactolipid bilayers in different lyotropic liquid-crystalline phases. Front Mol Biosci 2022; 9:958537. [PMID: 36046609 PMCID: PMC9423040 DOI: 10.3389/fmolb.2022.958537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 07/11/2022] [Indexed: 11/13/2022] Open
Abstract
In this study, carried out using computational methods, the organisation of the lipid/water interface of bilayers composed of galactolipids with both α-linolenoyl acyl chains is analysed and compared in three different lyotropic liquid-crystalline phases. These systems include the monogalactosyldiglyceride (MGDG) and digalactosyldiglyceride (DGDG) bilayers in the lamellar phase, the MGDG double bilayer during stalk phase formation and the inverse hexagonal MGDG phase. For each system, lipid-water and direct and water-mediated lipid-lipid interactions between the lipids of one bilayer leaflet and those of two apposing leaflets at the onset of new phase (stalk) formation, are identified. A network of interactions between DGDG molecules and its topological properties are derived and compared to those for the MGDG bilayer.
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Affiliation(s)
- Jakub Hryc
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Robert Szczelina
- Faculty of Mathematics and Computer Science, Jagiellonian University, Krakow, Poland
| | - Michal Markiewicz
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
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75
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Himbert S, D’Alessandro A, Qadri SM, Majcher MJ, Hoare T, Sheffield WP, Nagao M, Nagle JF, Rheinstädter MC. The bending rigidity of the red blood cell cytoplasmic membrane. PLoS One 2022; 17:e0269619. [PMID: 35913930 PMCID: PMC9342732 DOI: 10.1371/journal.pone.0269619] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/24/2022] [Indexed: 11/19/2022] Open
Abstract
An important mechanical property of cells is the membrane bending modulus, κ. In the case of red blood cells (RBCs) there is a composite membrane consisting of a cytoplasmic membrane and an underlying spectrin network. Literature values of κ are puzzling, as they are reported over a wide range, from 5 kBT to 230 kBT. To disentangle the contribution of the cytoplasmic membrane from the spectrin network, we investigated the bending of red blood cell cytoplasmic membranes (RBCcm) in the absence of spectrin and adenosine triphosphate (ATP). We used a combination of X-ray diffuse scattering (XDS), neutron spin-echo (NSE) spectrometry and Molecular Dynamics (MD) simulations. Our results indicate values of κ of order 4 kBT to 6 kBT, relatively small compared to literature values for most single component lipid bilayers. We suggest two ways this relative softness might confer biological advantage.
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Affiliation(s)
- Sebastian Himbert
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
- Origins Institute, McMaster University, Hamilton, ON, Canada
| | - Angelo D’Alessandro
- Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons and New York-Presbyterian Hospital, New York, New York, United States of America
- University of Colorado Denver-Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Syed M. Qadri
- Faculty of Health Sciences, Ontario Tech University, Oshawa, ON, Canada
| | - Michael J. Majcher
- Department of Chemical Engineering, McMaster University, Hamilton, ON, Canada
| | - Todd Hoare
- Department of Chemical Engineering, McMaster University, Hamilton, ON, Canada
| | - William P. Sheffield
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
- Centre for Innovation, Canadian Blood Services, Hamilton, ON, Canada
| | - Michihiro Nagao
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, United States of America
- Department of Materials Science and Engineering, University of Maryland, College Park, MD, United States of America
- Department of Physics and Astronomy, University of Delaware, Newark, DE, United States of America
| | - John F. Nagle
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, United States of America
| | - Maikel C. Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
- Origins Institute, McMaster University, Hamilton, ON, Canada
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76
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Zhang P, Jiao F, Wu L, Kong Z, Hu W, Liang L, Zhang Y. Molecular Dynamics Simulation of Transport Mechanism of Graphene Quantum Dots Through Different Cell Membranes. MEMBRANES 2022; 12:membranes12080753. [PMID: 36005668 PMCID: PMC9414618 DOI: 10.3390/membranes12080753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/25/2022] [Accepted: 07/27/2022] [Indexed: 11/16/2022]
Abstract
Exploring the mechanisms underlying the permeation of graphene quantum dots (GQDs) through different cell membranes is key for the practical application of GQDs in medicine. Here, the permeation process of GQDs through different lipid membranes was evaluated using molecular dynamics (MD) simulations. Our results showed that GQDs can easily permeate into 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) lipid membranes with low phospholipid molecule densities but cannot permeate into 1-palmitoyl-2-oleoyl phosphatidylethanolamine (POPE) lipid membranes with high phospholipid densities. Free energy calculation showed that a high-energy barrier exists on the surface of the POPE lipid membrane, which prevents GQDs from entering the cell membrane interior. Further analysis of the POPE membrane structure showed that sparsely arranged phospholipid molecules of the low-density lipid membrane facilitated the entry of GQDs into the interior of the membrane, compared to compactly arranged molecules in the high-density lipid membrane. Our simulation study provides new insights into the transmembrane transport of GQDs.
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Affiliation(s)
- Pengzhen Zhang
- Center of Advanced Optoelectronic Materials and Devices, Key Laboratory of Novel Materials for Sensor of Zhejiang Province, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China; (P.Z.); (L.W.); (Y.Z.)
| | - Fangfang Jiao
- Shandong Provincial Key Laboratory of Molecular Engineering, School of Chemistry and Pharmaceutical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China;
| | - Lingxiao Wu
- Center of Advanced Optoelectronic Materials and Devices, Key Laboratory of Novel Materials for Sensor of Zhejiang Province, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China; (P.Z.); (L.W.); (Y.Z.)
| | - Zhe Kong
- Center of Advanced Optoelectronic Materials and Devices, Key Laboratory of Novel Materials for Sensor of Zhejiang Province, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China; (P.Z.); (L.W.); (Y.Z.)
- Correspondence: (Z.K.); (W.H.)
| | - Wei Hu
- Shandong Provincial Key Laboratory of Molecular Engineering, School of Chemistry and Pharmaceutical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China;
- Correspondence: (Z.K.); (W.H.)
| | - Lijun Liang
- College of Automation, Hangzhou Dianzi University, Hangzhou 310018, China;
| | - Yongjun Zhang
- Center of Advanced Optoelectronic Materials and Devices, Key Laboratory of Novel Materials for Sensor of Zhejiang Province, College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China; (P.Z.); (L.W.); (Y.Z.)
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77
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Hanashima S, Mito K, Umegawa Y, Murata M, Hojo H. Lipid chain-driven interaction of a lipidated Src-family kinase Lyn with the bilayer membrane. Org Biomol Chem 2022; 20:6436-6444. [PMID: 35880995 DOI: 10.1039/d2ob01079h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
N-Myristoylation is a process of ubiquitous protein modification, which promotes the interaction of lipidated proteins on cell surfaces, in conjunction with reversible S-palmitoylation. We report the cooperative lipid-lipid interaction of two acyl chains of proteins, which increases the protein-membrane interaction and facilitates selective targeting of membranes containing anionic lipids. Lyn is a member of the Src family kinases distributed on the membrane surface by N-myristoyl and neighbouring S-palmitoyl chain anchors at the unique N-terminus domain. We prepared N-terminal short segments of lipidated Lyn to investigate the behaviour of each acyl chain in the lipid composition-dependent membrane interaction by solid-state nuclear magnetic resonance (NMR) analysis. Solid-state 31P-NMR studies revealed that S-palmitoylation of N-myristoylated Lyn peptides increased the interaction between peptides and phospholipid head groups, particularly with the anionic phosphatidylserine-containing bilayers. The solid-state 2H-NMR of Lyn peptides with a perdeutero N-myristoyl chain indicated an increase (0.6-0.8 Å) in the extent of the N-myristoyl chain in the presence of nearby S-palmitoyl chains, probably through the interaction via the acyl chains. The cooperative hydrocarbon chain interaction of the two acyl chains of Lyn increased membrane binding by extending the hydrocarbon chains deeper into the membrane interior, thereby promoting the peptide-membrane surface interaction between the cationic peptide side chains and the anionic lipid head groups. This lipid-driven mechanism by S-palmitoylation promotes the partition of the lipidated proteins to the cytoplasmic surface of the cell membranes and may be involved in recruiting Lyn at the signalling domains rich in anionic lipids.
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Affiliation(s)
- Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
| | - Kanako Mito
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
| | - Yuichi Umegawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan. .,Forefront Research Center, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Hironobu Hojo
- Forefront Research Center, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.,Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita 565-0871, Japan
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78
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Naz Z, Shrestha R, Moin ST, Monticelli L. Interaction of Phthalates with Lipid Bilayer Membranes. J Phys Chem B 2022; 126:4679-4688. [PMID: 35708295 DOI: 10.1021/acs.jpcb.2c02007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phthalates are esters of phthalic acid, widely used as additives in the manufacture of plastics. They are not covalently linked to polymer chains and can easily leach out, disperse in the environment, and get into contact with living organisms. Several short chain phthalates are classified as endocrine disruptors or hormonal active agents, and have also been reported to promote various kinds of cancer. However, the biological effects of longer chain analogues are less well known. Moreover, little is known on the permeation of phthalates and their metabolites through biological membranes and on their effects on the physical properties of membranes. Here we explore the interaction of a group of phthalates and their main metabolites with model biological membranes. We focus on three industrially relevant phthalates, with acyl chains of different sizes, and their monoester metabolites. We use molecular dynamics simulations to predict the distribution in model membranes, as well as permeabilities and effects on the structural, dynamic, and elastic properties of the membranes. We find that alterations of membrane properties are significant and only weakly affected by the size of acyl chains, suggesting that modifications of molecular size may not be sufficient to reduce the impact of this class of molecules on the environment and health.
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Affiliation(s)
- Zobia Naz
- Third World Center for Science and Technology, H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
| | - Roshan Shrestha
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS & University of Lyon, Lyon 69007, France
| | - Syed Tarique Moin
- Third World Center for Science and Technology, H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
| | - Luca Monticelli
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS & University of Lyon, Lyon 69007, France
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79
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Araya MK, Gorfe AA. Phosphatidylserine and Phosphatidylethanolamine Asymmetry Have a Negligible Effect on the Global Structure, Dynamics, and Interactions of the KRAS Lipid Anchor. J Phys Chem B 2022; 126:4491-4500. [PMID: 35687481 DOI: 10.1021/acs.jpcb.2c01253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The intrinsically disordered C-terminus of the prominent oncogenic protein KRAS-4B (KRAS) selectively interacts and clusters with phosphatidylserine (PS) lipids in the plasma membrane (PM). This 11-residue segment, called tK, contains a polybasic domain (PBD) of six contiguous lysine residues and a farnesylated cysteine. Previous molecular dynamics (MD) simulation studies of tK in phosphatidylcholine (PC)/PS bilayers have suggested that backbone conformational dynamics modulate tK-PS interactions. These simulations have been conducted in symmetric membranes whereas the PM is compositionally asymmetric, with the inner leaflet, where KRAS is localized, being enriched with PS and phosphatidylethanolamine (PE) lipids. To examine if bilayer asymmetry affects tK conformational dynamics and interaction with lipids, we conducted two 10 μs long MD simulations of tK bound to a PC/PS and a PC/PS/PE bilayer in which the PS and PE lipids are distributed in one leaflet. We found that, first, these compositional asymmetries caused differences in acyl chain dynamics between leaflets, but the equilibrium structural and dynamic properties of the two asymmetric bilayers are similar; second, in both systems tK is highly dynamic and samples at least two distinct conformational states; third, PS-tK hydrogen-bonding interactions vary with peptide backbone conformations, and lysine side chains in the PBD predominantly interact with the serine oxygens of PS. These results are in good agreement with previous observations of tK in symmetric membranes. The effects of POPS asymmetry or the presence of POPE on tK are limited to modulating the relative contribution of individual side chains to interactions with lipids and redistributing conformational substates. Additional observations include the larger flexibility of tK in the current simulations, which we attribute to the longer duration of the simulations and the use of the CHARMM36m force field, which more accurately models intrinsically disordered peptides such as tK.
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Affiliation(s)
- Mussie K Araya
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, 6431 Fannin St., Houston, Texas 77030, United States
| | - Alemayehu A Gorfe
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, 6431 Fannin St., Houston, Texas 77030, United States
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80
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Harris B, Huang Y, Karsai A, Su WC, Sambre PD, Parikh AN, Liu GY, Faller R. Impact of Surface Polarity on Lipid Assembly under Spatial Confinement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:7545-7557. [PMID: 35671406 PMCID: PMC9219405 DOI: 10.1021/acs.langmuir.2c00636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Molecular dynamics (MD) simulations in the MARTINI model are used to study the assembly of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) molecules under spatial confinement, such as during solvent evaporation from ultrasmall (femtoliter quantity) droplets. The impact of surface polarity on molecular assembly is discussed in detail. To the best of our knowledge, this work represents the first of its kind. Our results reveal that solvent evaporation gives rise to the formation of well-defined stacks of lipid bilayers in a smectic alignment. These smectic mesophases form on both polar and nonpolar surfaces but with a notable distinction. On polar surfaces, the director of the stack is oriented perpendicular to the support surface. By contrast, the stacks orient at an angle on the nonpolar surfaces. The packing of head groups on surfaces and lipid molecular mobility exhibits significant differences as surface polarity changes. The role of glycerol in the assembly and stability is also revealed. The insights revealed from the simulation have a significant impact on additive manufacturing, biomaterials, model membranes, and engineering protocells. For example, POPC assemblies via evaporation of ultrasmall droplets were produced and characterized. The trends compare well with the bilayer stack models. The surface polarity influences the local morphology and structures at the interfaces, which could be rationalized via the molecule-surface interactions observed from simulations.
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Affiliation(s)
- Bradley
S. Harris
- Department
of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Yuqi Huang
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Arpad Karsai
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Wan-Chih Su
- Department
of Biomedical Engineering, University of
California, Davis, California 95616, United States
| | - Pallavi D. Sambre
- Department
of Materials Science & Engineering, University of California, Davis, California 95616, United States
| | - Atul N. Parikh
- Department
of Biomedical Engineering, University of
California, Davis, California 95616, United States
| | - Gang-yu Liu
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Roland Faller
- Department
of Chemical Engineering, University of California, Davis, California 95616, United States
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81
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Robertson MJ, Skiniotis G. Development of OPLS-AA/M Parameters for Simulations of G Protein-Coupled Receptors and Other Membrane Proteins. J Chem Theory Comput 2022; 18:4482-4489. [PMID: 35687850 DOI: 10.1021/acs.jctc.2c00015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
G protein-coupled receptors (GPCRs) and other membrane proteins are valuable drug targets, and their dynamic nature makes them attractive systems for study with molecular dynamics (MD) simulations and free energy approaches. Here, we report the development, implementation, and validation of OPLS-AA/M force field parameters to enable simulations of these systems. These efforts include the introduction of post-translational modifications including lipidations and phosphorylation. We also modify previously reported parameters for lipids to be more consistent with the OPLS-AA force field standard and extend their coverage. These new parameters are validated on a variety of test systems, with the results compared to high-level quantum mechanics calculations, experimental data, and simulations with other force fields. The results demonstrate that the new parameters reliably reproduce the behavior of membrane protein systems.
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Affiliation(s)
- Michael J Robertson
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, United States.,Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, United States
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82
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Gilbert J, Ermilova I, Nagao M, Swenson J, Nylander T. Effect of encapsulated protein on the dynamics of lipid sponge phase: a neutron spin echo and molecular dynamics simulation study. NANOSCALE 2022; 14:6990-7002. [PMID: 35470842 DOI: 10.1039/d2nr00882c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Lipid membranes are highly mobile systems with hierarchical, time and length scale dependent, collective motions including thickness fluctuations, undulations, and topological membrane changes, which play an important role in membrane interactions. In this work we have characterised the effect of encapsulating two industrially important enzymes, β-galactosidase and aspartic protease, in lipid sponge phase nanoparticles on the dynamics of the lipid membrane using neutron spin echo (NSE) spectroscopy and molecular dynamics (MD) simulations. From NSE, reduced membrane dynamics were observed upon enzyme encapsulation, which were dependent on the enzyme concentration and type. By fitting the intermediate scattering functions (ISFs) with a modified Zilman and Granek model including nanoparticle diffusion, an increase in membrane bending rigidity was observed, with a larger effect for β-galactosidase than aspartic protease at the same concentration. MD simulations for the system with and without aspartic protease showed that the lipids relax more slowly in the system with protein due to the replacement of the lipid carbonyl-water hydrogen bonds with lipid-protein hydrogen bonds. This indicates that the most likely cause of the increase in membrane rigidity observed in the NSE measurements was dehydration of the lipid head groups. The dynamics of the protein itself were also studied, which showed a stable secondary structure of protein over the simulation, indicating no unfolding events occurred.
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Affiliation(s)
- Jennifer Gilbert
- Division of Physical Chemistry, Department of Chemistry, Naturvetarvägen 14, Lund University, 22362 Lund, Sweden.
- NanoLund, Lund University, Professorsgatan 1, 223 63 Lund, Sweden
| | - Inna Ermilova
- Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Michihiro Nagao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - Jan Swenson
- Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Tommy Nylander
- Division of Physical Chemistry, Department of Chemistry, Naturvetarvägen 14, Lund University, 22362 Lund, Sweden.
- NanoLund, Lund University, Professorsgatan 1, 223 63 Lund, Sweden
- Lund Institute of Advanced Neutron and X-Ray Science, Scheelevägen 19, 223 70 Lund, Sweden
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83
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Castillo SR, Rickeard BW, DiPasquale M, Nguyen MHL, Lewis-Laurent A, Doktorova M, Kav B, Miettinen MS, Nagao M, Kelley EG, Marquardt D. Probing the Link between Pancratistatin and Mitochondrial Apoptosis through Changes in the Membrane Dynamics on the Nanoscale. Mol Pharm 2022; 19:1839-1852. [PMID: 35559658 DOI: 10.1021/acs.molpharmaceut.1c00926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pancratistatin (PST) is a natural antiviral alkaloid that has demonstrated specificity toward cancerous cells and explicitly targets the mitochondria. PST initiates apoptosis while leaving healthy, noncancerous cells unscathed. However, the manner by which PST induces apoptosis remains elusive and impedes the advancement of PST as a natural anticancer therapeutic agent. Herein, we use neutron spin-echo (NSE) spectroscopy, molecular dynamics (MD) simulations, and supporting small angle scattering techniques to study PST's effect on membrane dynamics using biologically representative model membranes. Our data suggests that PST stiffens the inner mitochondrial membrane (IMM) by being preferentially associated with cardiolipin, which would lead to the relocation and release of cytochrome c. Second, PST has an ordering effect on the lipids and disrupts their distribution within the IMM, which would interfere with the maintenance and functionality of the active forms of proteins in the electron transport chain. These previously unreported findings implicate PST's effect on mitochondrial apoptosis.
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Affiliation(s)
- Stuart R Castillo
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Brett W Rickeard
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Mitchell DiPasquale
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Michael H L Nguyen
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Aislyn Lewis-Laurent
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Milka Doktorova
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22903, United States
| | - Batuhan Kav
- Max-Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany.,Institute of Biological Information Processing: Structural Biochemistry (IBI-7), Forschungszentrum Julich, Julich 52428, Germany
| | | | - Michihiro Nagao
- National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland 20899, United States.,Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States.,Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, United States
| | - Elizabeth G Kelley
- National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland 20899, United States
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada.,Department of Physics, University of Windsor, Windsor, Ontario N9B 3P4, Canada
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84
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Beasley M, Frazee N, Groover S, Valentine SJ, Mertz B, Legleiter J. Physicochemical Properties Altered by the Tail Group of Lipid Membranes Influence Huntingtin Aggregation and Lipid Binding. J Phys Chem B 2022; 126:3067-3081. [PMID: 35439000 DOI: 10.1021/acs.jpcb.1c10254] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Huntington's disease is a neurodegenerative disorder caused by an expanded polyglutamine (polyQ) domain within the huntingtin protein (htt) that initiates toxic protein aggregation. Htt directly interacts with membranes, influencing aggregation and spurring membrane abnormalities. These interactions are facilitated by the 17 N-terminal residues (Nt17) that form an amphipathic α-helix implicated in both lipid binding and aggregation. Here, the impact of unsaturation in phospholipid tails on htt-lipid interaction and htt aggregation was determined. There was no correlation between the degree of htt-lipid complexation and the degree of htt aggregation in the presence of each lipid system, indicating that lipid systems with different properties uniquely alter the membrane-mediated aggregation mechanisms. Also, the association between Nt17 and membrane surfaces is determined by complementarity between hydrophobic residues and membrane defects and how easily the peptide can partition into the bilayer. Our results provide critical insights into how membrane physical properties influence downstream htt aggregation.
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Affiliation(s)
- Maryssa Beasley
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States
| | - Nicolas Frazee
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States
| | - Sharon Groover
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States
| | - Stephen J Valentine
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States
| | - Blake Mertz
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States.,WVU Cancer Institute, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Justin Legleiter
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, West Virginia 26506, United States.,Blanchette Rockefeller Neurosciences Institutes, West Virginia University, 1 Medical Center Drive, P.O. Box 9303, Morgantown, West Virginia 26505, United States.,Department of Neuroscience, West Virginia University, 1 Medical Center Drive, P.O. Box 9303, Morgantown, West Virginia 26505, United States
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85
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Cao Y, Klein J. Lipids and lipid mixtures in boundary layers: From hydration lubrication to osteoarthritis. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2021.101559] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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86
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Yao QQ, Wen J, Perrett S, Wu S. Distinct lipid membrane-mediated pathways of Tau assembly revealed by single-molecule analysis. NANOSCALE 2022; 14:4604-4613. [PMID: 35260870 DOI: 10.1039/d1nr05960b] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The conversion of intrinsically disordered Tau to highly ordered amyloid aggregates is associated with a wide range of neurodegenerative diseases termed tauopathies. The presence of lipid bilayer membranes is a critical factor that accelerates the abnormal aggregation of Tau protein. However, the lipid membrane-induced conformational changes of Tau and the mechanism for the accelerated fibrillation remain elusive. In this study, single-molecule Förster resonance energy transfer (smFRET) and fluorescence correlation spectroscopy (FCS) were applied to detect the conformational changes and intermolecular interactions of full-length Tau in the presence of different concentrations of 1,2-dimyristoyl-sn-glycero-3-phosphatidylserine (DMPS) vesicles. The results show that the conformation of Tau becomes expanded with opening of the N-terminal and C-terminal domains of Tau upon binding to DMPS. At low DMPS concentrations, Tau forms oligomers with a partially extended conformation which facilitates the amyloid fibrillization process. At high DMPS concentrations, Tau monomer binds to lipid membranes in a fully expanded conformation at low density thus inhibiting intermolecular aggregation. Our study reveals the underlying mechanisms by which lipid membranes influence amyloid formation of Tau, providing a foundation for further understanding of the pathogenesis and physiology of the interplay between Tau protein and lipid membranes.
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Affiliation(s)
- Qiong-Qiong Yao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Jitao Wen
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Sarah Perrett
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Si Wu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
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87
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Faizi HA, Dimova R, Vlahovska PM. A vesicle microrheometer for high-throughput viscosity measurements of lipid and polymer membranes. Biophys J 2022; 121:910-918. [PMID: 35176271 PMCID: PMC8943812 DOI: 10.1016/j.bpj.2022.02.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/08/2022] [Accepted: 02/09/2022] [Indexed: 11/02/2022] Open
Abstract
Viscosity is a key property of cell membranes that controls mobility of embedded proteins and membrane remodeling. Measuring it is challenging because existing approaches involve complex experimental designs and/or models, and the applicability of some methods is limited to specific systems and membrane compositions. As a result there is scarcity of systematic data, and the reported values for membrane viscosity vary by orders of magnitude for the same system. Here, we show how viscosity of membranes can be easily obtained from the transient deformation of giant unilamellar vesicles. The approach enables a noninvasive, probe-independent, and high-throughput measurement of the viscosity of membranes made of lipids or polymers with a wide range of compositions and phase state. Using this novel method, we have collected a significant amount of data that provides insights into the relation between membrane viscosity, composition, and structure.
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Affiliation(s)
- Hammad A Faizi
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois
| | - Rumiana Dimova
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - Petia M Vlahovska
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois.
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88
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Adams WR, Gautam R, Locke A, Masson LE, Borrachero-Conejo AI, Dollinger B, Throckmorton GA, Duvall C, Jansen ED, Mahadevan-Jansen A. Visualizing Lipid Dynamics Role in Infrared Neural Stimulation using Stimulated Raman Scattering. Biophys J 2022; 121:1525-1540. [PMID: 35276133 PMCID: PMC9072573 DOI: 10.1016/j.bpj.2022.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/14/2021] [Accepted: 03/04/2022] [Indexed: 11/02/2022] Open
Abstract
Infrared neural stimulation, or INS, uses pulsed infrared light to yield label-free neural stimulation with broad experimental and translational utility. Despite its robust demonstration, INS's mechanistic and biophysical underpinnings have been the subject of debate for more than a decade. The role of lipid membrane thermodynamics appears to play an important role in how fast IR-mediated heating nonspecifically drives action potential generation. Direct observation of lipid membrane dynamics during INS remains to be shown in a live neural model system. We used hyperspectral stimulated Raman scattering (hsSRS) microscopy to study biochemical signatures of high-speed vibrational dynamics underlying INS in a live neural cell culture model. Findings suggest that lipid bilayer structural changes are occurring during INS in vitro in NG108-15 neuroglioma cells. Lipid-specific signatures of cell SRS spectra varied with stimulation energy and radiant exposure. Spectroscopic observations agree with high-speed ratiometric fluorescence imaging of a conventional lipophilic membrane structure reporter, di-4-ANNEPS. Overall, the presented findings support the hypothesis that INS causes changes in the lipid membrane of neural cells by changing lipid membrane packing order. Furthermore, this work highlights the potential of hsSRS as a method to study biophysical and biochemical dynamics safely in live cells.
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Affiliation(s)
- Wilson R Adams
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Rekha Gautam
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Andrea Locke
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Laura E Masson
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | | | - Bryan Dollinger
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | | | - Craig Duvall
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - E Duco Jansen
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Dept. of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Anita Mahadevan-Jansen
- Dept. of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Dept. of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, USA.
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89
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Gomez YK, Natale AM, Lincoff J, Wolgemuth CW, Rosenberg JM, Grabe M. Taking the Monte-Carlo gamble: How not to buckle under the pressure! J Comput Chem 2022; 43:431-434. [PMID: 34921560 PMCID: PMC8776593 DOI: 10.1002/jcc.26798] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 11/19/2021] [Accepted: 11/25/2021] [Indexed: 11/08/2022]
Abstract
Consistent buckling distortions of a large membrane patch (200 × 200 Å) are observed during molecular dynamics (MD) simulations using the Monte-Carlo (MC) barostat in combination with a hard Lennard-Jones (LJ) cutoff. The buckling behavior is independent of both the simulation engine and the force field but requires the MC barostat-hard LJ cutoff combination. Similar simulations of a smaller patch (90 × 90 Å) do not show buckling, but do show a small, systematic reduction in the surface area accompanied by ~1 Å thickening suggestive of compression. We show that a mismatch in the way potentials and forces are handled in the dynamical equations versus the MC barostat results in a compressive load on the membrane. Moreover, a straightforward application of elasticity theory reveals that a minimal compression of the linear dimensions of the membrane, inversely proportional to the edge length, is required for buckling, explaining this differential behavior. We recommend always using LJ force or potential-switching when the MC barostat is employed to avoid undesirable membrane deformations.
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Affiliation(s)
- Yessica K. Gomez
- Cardiovascular Research Institute, Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - Andrew M. Natale
- Cardiovascular Research Institute, Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - James Lincoff
- Cardiovascular Research Institute, Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - Charles W. Wolgemuth
- Departments of Molecular and Cellular Biology and Physics, University of Arizona, Tucson, Arizona, USA
| | - John M. Rosenberg
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Michael Grabe
- Cardiovascular Research Institute, Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
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90
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Kashyap HK. Deciphering Ethanol-Driven Swelling, Rupturing, Aggregation, and Fusion of Lipid Vesicles Using Coarse-Grained Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2445-2459. [PMID: 35167280 DOI: 10.1021/acs.langmuir.1c02763] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Traditionally, liquid ethanol is known to enhance the permeability of lipid membranes and causes vesicle aggregation and fusion. However, how the amphiphilic ethanol molecules perturb the lipid vesicles to facilitate their aggregation or fusion has not been addressed at any level of molecular simulations. Herein, not only have we developed a coarse-grained (CG) model for liquid ethanol, its aqueous mixture, and hydrated lipid membranes for molecular dynamics (MD) simulations, but also utilized it to delineate the aggregation and fusion of lipid vesicles using CG-MD simulations with multimillion particles. We have systematically parametrized the force-field for pure ethanol and its interactions with hydrated POPC and POPE model lipid membranes. In this process, we have successfully reproduced the bulk ethanol structure and concentration-dependent density of aqueous ethanol. To quantify the interaction of ethanol with lipid membranes, we have reproduced the transfer free energy of the ethanol molecule across the hydrated bilayers, and the concentration-dependent distribution of ethanol molecules across the lipid bilayers. After having acceptable force-field parameters for ethanol-membrane interactions, we have checked the effect of ethanol toward the vesicles comprising POPC lipids. We observe a rapid increase in the size of the POPC lipid vesicles with increasing amounts of ethanol up to 30 mol %. We unambiguously observe swelling and decrease in the thickness of the POPC vesicles with increasing amounts of ethanol up to 30 mol %, beyond which the vesicles begin to lose their integrity and rupture at higher mol % of ethanol. The fusion study of two vesicles demonstrates that fused vesicles can be obtained from 20 to 30 mol % of ethanol provided that they are brought closer than a critical distance at a particular mol %. The multivesicle simulations show that along with the increase in the sizes of vesicles the propensity of vesicle aggregation increases as the mol % of ethanol increases.
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Affiliation(s)
- Hemant K Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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91
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Pogozheva ID, Armstrong GA, Kong L, Hartnagel TJ, Carpino CA, Gee SE, Picarello DM, Rubin AS, Lee J, Park S, Lomize AL, Im W. Comparative Molecular Dynamics Simulation Studies of Realistic Eukaryotic, Prokaryotic, and Archaeal Membranes. J Chem Inf Model 2022; 62:1036-1051. [PMID: 35167752 DOI: 10.1021/acs.jcim.1c01514] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We present a comparative all-atom molecular dynamics simulation study of 18 biomembrane systems with lipid compositions corresponding to eukaryotic, bacterial, and archaebacterial membranes together with three single-component lipid bilayers. A total of 105 lipid types used in this study include diverse sterols and glycerol-based lipids with acyl chains of various lengths, unsaturation degrees, and branched or cyclic moieties. Our comparative analysis provides deeper insight into the influences of sterols and lipid unsaturation on the structural and mechanical properties of these biomembranes, including water permeation into the membrane hydrocarbon core. For sterol-containing membranes, sterol fraction is correlated with the membrane thickness, the area compressibility modulus, and lipid order but anticorrelated with the area per lipid and sterol tilt angles. Similarly, for all 18 biomembranes, lipid order is correlated with the membrane thickness and area compressibility modulus. Sterols and lipid unsaturation produce opposite effects on membrane thickness, but only sterols influence water permeation into the membrane. All membrane systems are accessible for public use in CHARMM-GUI Archive. They can be used as templates to expedite future modeling of realistic cell membranes with transmembrane and peripheral membrane proteins to study their structure, dynamics, molecular interactions, and function in a nativelike membrane environment.
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Affiliation(s)
- Irina D Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Grant A Armstrong
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Lingyang Kong
- Department of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Timothy J Hartnagel
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Carly A Carpino
- Department of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Stephen E Gee
- Department of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Danielle M Picarello
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Amanda S Rubin
- Department of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Jumin Lee
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Soohyung Park
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Andrei L Lomize
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Wonpil Im
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, United States.,Department of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States.,Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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92
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Maiti A, Daschakraborty S. Can Urea and Trimethylamine- N-oxide Prevent the Pressure-Induced Phase Transition of Lipid Membrane? J Phys Chem B 2022; 126:1426-1440. [PMID: 35139638 DOI: 10.1021/acs.jpcb.1c08891] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Organisms dwelling in ocean trenches are exposed to the high hydrostatic pressure of ocean water. Increasing pressure can alter the membrane packing density and fluidity and trigger the fluid-to-gel phase transition. To combat environmental stress, the organisms synthesize small polar solutes, which are known as osmolytes. Urea and trimethylamine-N-oxide (TMAO) are two such solutes found in deep-sea creatures. While TMAO stabilizes protein, urea induces protein denaturation. These solutes strongly influence the packing density and membrane fluidity of the lipid bilayer at different conditions. But can these solutes affect the pressure-induced phase transition of the lipid membrane? In the present work, we have studied the effect of these two solutes on pressure-induced fluid-to-gel phase transition based on the all-atom molecular dynamics (MD) simulation approach. A high-pressure-stimulated fluid-to-gel phase transition of the membrane is seen at 800 bar, which is consistent with previous experiments. We have also observed that in the low-pressure region (1-400 bar), urea slightly increases the membrane fluidity where TMAO decreases the same. However, the phase transition pressure remains almost unchanged on the addition of urea while TMAO shifts the phase transition toward a lower pressure. We have found that the hydrogen (H)-bond interaction between lipid and urea plays an important role in preserving the fluidity of the membrane in the low-pressure zone. However, at a higher pressure, both water and urea are excluded from the membrane surface. TMAO is also excluded from the interfacial region of the membrane at all pressures. Exclusion from the membrane surface further triggers the phase transition of the lipid membrane from the fluid to gel phase at a high pressure.
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Affiliation(s)
- Archita Maiti
- Department of Chemistry, Indian Institute of Technology Patna, Bihar 801106, India
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93
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Van Zee NJ, Peroutka AS, Crabtree A, Hillmyer MA, Lodge TP. Lipid Membrane Binding and Cell Protection Efficacy of Poly(1,2-butylene oxide)- b-poly(ethylene oxide) Copolymers. Biomacromolecules 2022; 23:1433-1442. [PMID: 35132851 DOI: 10.1021/acs.biomac.1c01661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Poloxamers consisting of poly(ethylene oxide) (PEO) and poly(propylene oxide) segments can protect cell membranes against various forms of stress. We investigated the role of the hydrophobic block chemistry on polymer/membrane binding and cell membrane protection by comparing a series of poly(butylene oxide)-b-PEO (PBO-b-PEO) copolymers to poloxamer analogues, using a combination of pulsed-field-gradient (PFG) NMR experiments and a lactate dehydrogenase (LDH) cell assay. We found that the more hydrophobic PBO-b-PEO copolymers bound more significantly to model liposomes composed of 1-palmitol-2-oleoyl-glycero-3-phosphocholine (POPC) compared to poly(propylene oxide) (PPO)/PEO copolymers. However, both classes of polymers performed similarly when compared by an LDH assay. These results present an important comparison between polymers with similar structures but with different binding affinities. They also provide mechanistic insight as enhanced polymer/lipid membrane binding did not directly translate to increased cell protection in the LDH assay, and therefore, additional factors need to be considered when trying to achieve greater membrane protection efficacy.
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94
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Abstract
![]()
We extend the modular AMBER lipid
force field to include anionic
lipids, polyunsaturated fatty acid (PUFA) lipids, and sphingomyelin,
allowing the simulation of realistic cell membrane lipid compositions,
including raft-like domains. Head group torsion parameters are revised,
resulting in improved agreement with NMR order parameters, and hydrocarbon
chain parameters are updated, providing a better match with phase
transition temperature. Extensive validation runs (0.9 μs per
lipid type) show good agreement with experimental measurements. Furthermore,
the simulation of raft-like bilayers demonstrates the perturbing effect
of increasing PUFA concentrations on cholesterol molecules. The force
field derivation is consistent with the AMBER philosophy, meaning
it can be easily mixed with protein, small molecule, nucleic acid,
and carbohydrate force fields.
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Affiliation(s)
- Callum J Dickson
- Computer-Aided Drug Discovery, Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Ross C Walker
- GlaxoSmithKline PLC, 1250 S. Collegeville Road, Collegeville, Pennsylvania 19426, United States.,Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Ian R Gould
- Department of Chemistry, Imperial College London, London, SW7 2AZ, U.K
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95
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Kawaguchi K, Ito S, Saito H, Nagao H. Molecular dynamics study of lipid bilayer asymmetry induced by ion concentration gradient and electronic polarizability. MOLECULAR SIMULATION 2022. [DOI: 10.1080/08927022.2022.2025798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Kazutomo Kawaguchi
- Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan
| | - Seiichiro Ito
- Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan
| | - Hiroaki Saito
- Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan
| | - Hidemi Nagao
- Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan
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96
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Moutoussamy EE, Waheed Q, Binford GJ, Khan HM, Moran SM, Eitel AR, Cordes MHJ, Reuter N. Specificity of Loxosceles α clade phospholipase D enzymes for choline-containing lipids: Role of a conserved aromatic cage. PLoS Comput Biol 2022; 18:e1009871. [PMID: 35180220 PMCID: PMC8893692 DOI: 10.1371/journal.pcbi.1009871] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 03/03/2022] [Accepted: 01/27/2022] [Indexed: 11/18/2022] Open
Abstract
Spider venom GDPD-like phospholipases D (SicTox) have been identified to be one of the major toxins in recluse spider venom. They are divided into two major clades: the α clade and the β clade. Most α clade toxins present high activity against lipids with choline head groups such as sphingomyelin, while activities in β clade toxins vary and include preference for substrates containing ethanolamine headgroups (Sicarius terrosus, St_βIB1). A structural comparison of available structures of phospholipases D (PLDs) reveals a conserved aromatic cage in the α clade. To test the potential influence of the aromatic cage on membrane-lipid specificity we performed molecular dynamics (MD) simulations of the binding of several PLDs onto lipid bilayers containing choline headgroups; two SicTox from the α clade, Loxosceles intermedia αIA1 (Li_αIA) and Loxosceles laeta αIII1 (Ll_αIII1), and one from the β clade, St_βIB1. The simulation results reveal that the aromatic cage captures a choline-headgroup and suggest that the cage plays a major role in lipid specificity. We also simulated an engineered St_βIB1, where we introduced the aromatic cage, and this led to binding with choline-containing lipids. Moreover, a multiple sequence alignment revealed the conservation of the aromatic cage among the α clade PLDs. Here, we confirmed that the i-face of α and β clade PLDs is involved in their binding to choline and ethanolamine-containing bilayers, respectively. Furthermore, our results suggest a major role in choline lipid recognition of the aromatic cage of the α clade PLDs. The MD simulation results are supported by in vitro liposome binding assay experiments. Envenomation following bites from recluse spiders (Loxosceles) causes loxoscelism, a necrotic tissue breakdown in mammals, and leads to skin degeneration and systemic reactions in the worst case. Recluse spiders belong to the Sicariidae family which also includes six-eyed sand spiders in the genera Sicarius and Hexopthalma. While sicariid spiders are found natively on all continents except Australia, treatments of loxoscelism are typically antibody based and available in some regions of the Americas. Sphingomyelinase D/phospholipase D enzymes are one of the major toxins in venom of sicariid spiders, and have been divided in two clades called α and β. The activity of α and β clades toxins differs; most α clade toxins present high activity against lipids with choline headgroups (-N (CH3)3+) such as sphingomyelin, while activities in β clade toxins vary and include preference for substrates containing ethanolamine headgroups (-NH3+). When comparing the structures of two α clade toxins and one β clade toxin, we noticed the presence in the α clade toxins only of a cage consisting of three aromatic amino acids. In this work we used numerical molecular simulations to probe the role of this cage in the preference of α clade toxins for choline head groups over ethanolamine head groups.
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Affiliation(s)
- Emmanuel E. Moutoussamy
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Qaiser Waheed
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Greta J. Binford
- Department of Biology, Lewis and Clark College, Portland, Oregon, United States
| | - Hanif M. Khan
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Shane M. Moran
- Department of Chemistry and Biochemistry, University of Arizona, Arizona, United States
| | - Anna R. Eitel
- Department of Chemistry and Biochemistry, University of Arizona, Arizona, United States
| | - Matthew H. J. Cordes
- Department of Chemistry and Biochemistry, University of Arizona, Arizona, United States
| | - Nathalie Reuter
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Department of Chemistry, University of Bergen, Bergen, Norway
- * E-mail:
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97
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Karal MAS, Mokta NA, Levadny V, Belaya M, Ahmed M, Ahamed MK, Ahammed S. Effects of cholesterol on the size distribution and bending modulus of lipid vesicles. PLoS One 2022; 17:e0263119. [PMID: 35089965 PMCID: PMC8797199 DOI: 10.1371/journal.pone.0263119] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 01/12/2022] [Indexed: 11/19/2022] Open
Abstract
The influence of cholesterol fraction in the membranes of giant unilamellar vesicles (GUVs) on their size distributions and bending moduli has been investigated. The membranes of GUVs were synthesized by a mixture of two elements: electrically neutral lipid 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol and also a mixture of three elements: electrically charged lipid 1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DOPG), DOPC and cholesterol. The size distributions of GUVs have been presented by a set of histograms. The classical lognormal distribution is well fitted to the histograms, from where the average size of vesicle is obtained. The increase of cholesterol content in the membranes of GUVs increases the average size of vesicles in the population. Using the framework of Helmholtz free energy of the system, the theory developed by us is extended to explain the experimental results. The theory determines the influence of cholesterol on the bending modulus of membranes from the fitting of the proper histograms. The increase of cholesterol in GUVs increases both the average size of vesicles in population and the bending modulus of membranes.
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Affiliation(s)
- Mohammad Abu Sayem Karal
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
- * E-mail:
| | - Nadia Akter Mokta
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - Victor Levadny
- Theoretical Problem Center of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
| | - Marina Belaya
- Department of Mathematics of Russian State University for the Humanities, Moscow, Russia
| | - Marzuk Ahmed
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - Md. Kabir Ahamed
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - Shareef Ahammed
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
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98
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Irwin MJ, Wang X, Cote RH. Reconstitution of Membrane-associated Components of a G-protein Signaling Pathway on Membrane-coated Nanoparticles (Lipobeads). Bio Protoc 2022; 12:e4303. [PMID: 35127993 PMCID: PMC8799665 DOI: 10.21769/bioprotoc.4303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 11/28/2021] [Accepted: 11/30/2021] [Indexed: 11/01/2023] Open
Abstract
G-protein coupled signaling pathways are organized into multi-protein complexes called signalosomes that are located within and on cellular membranes. We describe the use of silica nanoparticles coated with a unilamellar phospholipid bilayer (lipobeads) to reconstitute the activated photoreceptor G-protein α-subunit (Gtα*) with its cognate effector (phosphodiesterase-6; PDE6) for biochemical and structural studies of the activation mechanism regulating this GPCR signaling pathway. Lipobeads are prepared by resuspending dried-down phospholipid mixtures with monodisperse 70 nm silica particles, followed by extrusion through a 100 nm membrane filter. This uniform and supported liposomal preparation is easily sedimented, permitting the separation of soluble from membrane-associated proteins. Upon loading lipobeads with Gtα* and PDE6, we find that activation of PDE6 catalysis by Gtα* occurs much more efficiently than in the absence of membranes. Chemical cross-linking of membrane-confined proteins allows detection of changes in protein-protein interactions, resulting from G-protein activation of PDE6. The advantages of using lipobeads over partially purified membrane preparations or traditional liposomal preparations are generally applicable to the study of other membrane-confined signal transduction pathways.
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Affiliation(s)
- Michael J. Irwin
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Xin Wang
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Rick H. Cote
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA
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99
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Tsai CY, Salawu EO, Li H, Lin GY, Kuo TY, Voon L, Sharma A, Hu KD, Cheng YY, Sahoo S, Stuart L, Chen CW, Chang YY, Lu YL, Ke S, Ortiz CLD, Fang BS, Wu CC, Lan CY, Fu HW, Yang LW. Helical structure motifs made searchable for functional peptide design. Nat Commun 2022; 13:102. [PMID: 35013238 PMCID: PMC8748493 DOI: 10.1038/s41467-021-27655-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 12/03/2021] [Indexed: 11/09/2022] Open
Abstract
The systematic design of functional peptides has technological and therapeutic applications. However, there is a need for pattern-based search engines that help locate desired functional motifs in primary sequences regardless of their evolutionary conservation. Existing databases such as The Protein Secondary Structure database (PSS) no longer serves the community, while the Dictionary of Protein Secondary Structure (DSSP) annotates the secondary structures when tertiary structures of proteins are provided. Here, we extract 1.7 million helices from the PDB and compile them into a database (Therapeutic Peptide Design database; TP-DB) that allows queries of compounded patterns to facilitate the identification of sequence motifs of helical structures. We show how TP-DB helps us identify a known purification-tag-specific antibody that can be repurposed into a diagnostic kit for Helicobacter pylori. We also show how the database can be used to design a new antimicrobial peptide that shows better Candida albicans clearance and lower hemolysis than its template homologs. Finally, we demonstrate how TP-DB can suggest point mutations in helical peptide blockers to prevent a targeted tumorigenic protein-protein interaction. TP-DB is made available at http://dyn.life.nthu.edu.tw/design/ .
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Affiliation(s)
- Cheng-Yu Tsai
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan.,Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, 100025, Taiwan.,Department of Otolaryngology, National Taiwan University Hospital, Taipei, 100225, Taiwan
| | - Emmanuel Oluwatobi Salawu
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan.,Bioinformatics Program, Institute of Information Sciences, Academia Sinica, Taipei, 115201, Taiwan.,Machine Learning Solutions Lab, Amazon Web Services (AWS), Herndon, VA, USA
| | - Hongchun Li
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan.,Research Center for Computer-Aided Drug Discovery, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China.,College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China.,Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Guan-Yu Lin
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Ting-Yu Kuo
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Liyin Voon
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Adarsh Sharma
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Kai-Di Hu
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Yi-Yun Cheng
- Praexisio Taiwan Inc., New Taipei, 221425, Taiwan
| | - Sobha Sahoo
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Lutimba Stuart
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Chih-Wei Chen
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Yuan-Yu Chang
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan.,Praexisio Taiwan Inc., New Taipei, 221425, Taiwan
| | - Yu-Lin Lu
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Simai Ke
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Christopher Llynard D Ortiz
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan.,Chemical Biology and Molecular Biophysics Program, Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan.,Department of Chemistry, National Tsing Hua University, Hsinchu, 300044, Taiwan
| | - Bai-Shan Fang
- College of Chemistry and Chemical Engineering, Xiamen University, 361005, Xiamen, China.,The Key Laboratory for Chemical Biology of Fujian Province, Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, 361005, Xiamen, China
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, 100225, Taiwan.,Department of Medical Research, National Taiwan University Hospital Hsin-Chu Branch, Hsinchu, 302058, Taiwan
| | - Chung-Yu Lan
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan. .,Department of Life Science, National Tsing Hua University, Hsinchu, 300044, Taiwan.
| | - Hua-Wen Fu
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan. .,Department of Life Science, National Tsing Hua University, Hsinchu, 300044, Taiwan.
| | - Lee-Wei Yang
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300044, Taiwan. .,Bioinformatics Program, Institute of Information Sciences, Academia Sinica, Taipei, 115201, Taiwan. .,Physics Division, National Center for Theoretical Sciences, Taipei, 106319, Taiwan. .,PhD Program in Biomedical Artificial Intelligence, National Tsing Hua University, Hsinchu, 300044, Taiwan.
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100
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Kneiszl R, Hossain S, Larsson P. In Silico-Based Experiments on Mechanistic Interactions between Several Intestinal Permeation Enhancers with a Lipid Bilayer Model. Mol Pharm 2022; 19:124-137. [PMID: 34913341 PMCID: PMC8728740 DOI: 10.1021/acs.molpharmaceut.1c00689] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/12/2021] [Accepted: 11/16/2021] [Indexed: 01/07/2023]
Abstract
Oral administration of drugs is generally considered convenient and patient-friendly. However, oral administration of biological drugs exhibits low oral bioavailability (BA) due to enzymatic degradation and low intestinal absorption. A possible approach to circumvent the low BA of oral peptide drugs is to coformulate the drugs with permeation enhancers (PEs). PEs have been studied since the 1960s and are molecules that enhance the absorption of hydrophilic molecules with low permeability over the gastrointestinal epithelium. In this study, we investigated the impact of six PEs on the structural properties of a model membrane using molecular dynamics (MD) simulations. The PEs included were the sodium salts of the medium chain fatty acids laurate, caprate, and caprylate and the caprylate derivative SNAC─all with a negative charge─and neutral caprate and neutral sucrose monolaurate. Our results indicated that the PEs, once incorporated into the membrane, could induce membrane leakiness in a concentration-dependent manner. Our simulations suggest that a PE concentration of at least 70-100 mM is needed to strongly affect transcellular permeability. The increased aggregation propensity seen for neutral PEs might provide a molecular-level mechanism for the membrane disruptions seen at higher concentrations in vivo. The ability for neutral PEs to flip-flop across the lipid bilayer is also suggestive of possible intracellular modes of action other than increasing membrane fluidity. Taken together, our results indicate that MD simulations are useful for gaining insights relevant to the design of oral dosage forms based around permeability enhancer molecules.
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Affiliation(s)
- Rosita Kneiszl
- Department
of Pharmacy, Uppsala University, Husargatan 3, Uppsala 751 23, Sweden
- The
Swedish Drug Delivery Center (SweDeliver), Uppsala University, Husargatan 3, Uppsala 751 23, Sweden
| | - Shakhawath Hossain
- Department
of Pharmacy, Uppsala University, Husargatan 3, Uppsala 751 23, Sweden
- The
Swedish Drug Delivery Center (SweDeliver), Uppsala University, Husargatan 3, Uppsala 751 23, Sweden
| | - Per Larsson
- Department
of Pharmacy, Uppsala University, Husargatan 3, Uppsala 751 23, Sweden
- The
Swedish Drug Delivery Center (SweDeliver), Uppsala University, Husargatan 3, Uppsala 751 23, Sweden
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