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Skeens A, Markle JM, Petipas G, Frey SL, Legleiter J. Divalent cations promote huntingtin fibril formation on endoplasmic reticulum derived and model membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184339. [PMID: 38763270 DOI: 10.1016/j.bbamem.2024.184339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 04/24/2024] [Accepted: 05/12/2024] [Indexed: 05/21/2024]
Abstract
Huntington's Disease (HD) is caused by an abnormal expansion of the polyglutamine (polyQ) domain within the first exon of the huntingtin protein (htt). This expansion promotes disease-related htt aggregation into amyloid fibrils and the formation of proteinaceous inclusion bodies within neurons. Fibril formation is a complex heterogenous process involving an array of aggregate species such as oligomers, protofibrils, and fibrils. In HD, structural abnormalities of membranes of several organelles develop. In particular, the accumulation of htt fibrils near the endoplasmic reticulum (ER) impinges upon the membrane, resulting in ER damage, altered dynamics, and leakage of Ca2+. Here, the aggregation of htt at a bilayer interface assembled from ER-derived liposomes was investigated, and fibril formation directly on these membranes was enhanced. Based on these observations, simplified model systems were used to investigate mechanisms associated with htt aggregation on ER membranes. As the ER-derived liposome fractions contained residual Ca2+, the role of divalent cations was also investigated. In the absence of lipids, divalent cations had minimal impact on htt structure and aggregation. However, the presence of Ca2+ or Mg2+ played a key role in promoting fibril formation on lipid membranes despite reduced htt insertion into and association with lipid interfaces, suggesting that the ability of divalent cations to promote fibril formation on membranes is mediated by induced changes to the lipid membrane physicochemical properties. With enhanced concentrations of intracellular calcium being a hallmark of HD, the ability of divalent cations to influence htt aggregation at lipid membranes may play a role in aggregation events that lead to organelle abnormalities associated with disease.
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Affiliation(s)
- Adam Skeens
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, WV 26506, USA
| | - Jordyn M Markle
- The Department of Chemistry, Gettysburg College, 300 N. Washington Street, Gettysburg, PA 17325, USA
| | - Gabriella Petipas
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, WV 26506, USA
| | - Shelli L Frey
- The Department of Chemistry, Gettysburg College, 300 N. Washington Street, Gettysburg, PA 17325, USA.
| | - Justin Legleiter
- The C. Eugene Bennett Department of Chemistry, West Virginia University, 217 Clark Hall, Morgantown, WV 26506, USA; Rockefeller Neurosciences Institutes, West Virginia University, 1 Medical Center Dr., P.O. Box 9303, Morgantown, WV 26505, USA; Department of Neuroscience, West Virginia University, 1 Medical Center Dr., P.O. Box 9303, Morgantown, WV 26505, USA.
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2
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Královič-Kanjaková N, Asi Shirazi A, Hubčík L, Klacsová M, Keshavarzi A, Martínez JC, Combet S, Teixeira J, Uhríková D. Polymyxin B-Enriched Exogenous Lung Surfactant: Thermodynamics and Structure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:6847-6861. [PMID: 38501650 DOI: 10.1021/acs.langmuir.3c03746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
The use of an exogenous pulmonary surfactant (EPS) to deliver other relevant drugs to the lungs is a promising strategy for combined therapy. We evaluated the interaction of polymyxin B (PxB) with a clinically used EPS, the poractant alfa Curosurf (PSUR). The effect of PxB on the protein-free model system (MS) composed of four phospholipids (diC16:0PC/16:0-18:1PC/16:0-18:2PC/16:0-18:1PG) was examined in parallel to distinguish the specificity of the composition of PSUR. We used several experimental techniques (differential scanning calorimetry, small- and wide-angle X-ray scattering, small-angle neutron scattering, fluorescence spectroscopy, and electrophoretic light scattering) to characterize the binding of PxB to both EPS. Electrostatic interactions PxB-EPS are dominant. The results obtained support the concept of cationic PxB molecules lying on the surface of the PSUR bilayer, strengthening the multilamellar structure of PSUR as derived from SAXS and SANS. A protein-free MS mimics a natural EPS well but was found to be less resistant to penetration of PxB into the lipid bilayer. PxB does not affect the gel-to-fluid phase transition temperature, Tm, of PSUR, while Tm increased by ∼+ 2 °C in MS. The decrease of the thickness of the lipid bilayer (dL) of PSUR upon PxB binding is negligible. The hydrophobic tail of the PxB molecule does not penetrate the bilayer as derived from SANS data analysis and changes in lateral pressure monitored by excimer fluorescence at two depths of the hydrophobic region of the bilayer. Changes in dL of protein-free MS show a biphasic dependence on the adsorbed amount of PxB with a minimum close to the point of electroneutrality of the mixture. Our results do not discourage the concept of a combined treatment with PxB-enriched Curosurf. However, the amount of PxB must be carefully assessed (less than 5 wt % relative to the mass of the surfactant) to avoid inversion of the surface charge of the membrane.
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Affiliation(s)
- Nina Královič-Kanjaková
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, 832 32 Bratislava, Slovakia
| | - Ali Asi Shirazi
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, 832 32 Bratislava, Slovakia
| | - Lukáš Hubčík
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, 832 32 Bratislava, Slovakia
| | - Mária Klacsová
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, 832 32 Bratislava, Slovakia
| | - Atoosa Keshavarzi
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, 832 32 Bratislava, Slovakia
| | | | - Sophie Combet
- Laboratoire Léon-Brillouin (LLB), UMR12 CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette CEDEX, France
| | - José Teixeira
- Laboratoire Léon-Brillouin (LLB), UMR12 CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette CEDEX, France
| | - Daniela Uhríková
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, 832 32 Bratislava, Slovakia
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3
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Keshavarzi A, Asi Shirazi A, Korfanta R, Královič N, Klacsová M, Martínez JC, Teixeira J, Combet S, Uhríková D. Thermodynamic and Structural Study of Budesonide-Exogenous Lung Surfactant System. Int J Mol Sci 2024; 25:2990. [PMID: 38474237 DOI: 10.3390/ijms25052990] [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: 01/19/2024] [Revised: 02/22/2024] [Accepted: 03/01/2024] [Indexed: 03/14/2024] Open
Abstract
The clinical benefits of using exogenous pulmonary surfactant (EPS) as a carrier of budesonide (BUD), a non-halogenated corticosteroid with a broad anti-inflammatory effect, have been established. Using various experimental techniques (differential scanning calorimetry DSC, small- and wide- angle X-ray scattering SAXS/WAXS, small- angle neutron scattering SANS, fluorescence spectroscopy, dynamic light scattering DLS, and zeta potential), we investigated the effect of BUD on the thermodynamics and structure of the clinically used EPS, Curosurf®. We show that BUD facilitates the Curosurf® phase transition from the gel to the fluid state, resulting in a decrease in the temperature of the main phase transition (Tm) and enthalpy (ΔH). The morphology of the Curosurf® dispersion is maintained for BUD < 10 wt% of the Curosurf® mass; BUD slightly increases the repeat distance d of the fluid lamellar phase in multilamellar vesicles (MLVs) resulting from the thickening of the lipid bilayer. The bilayer thickening (~0.23 nm) was derived from SANS data. The presence of ~2 mmol/L of Ca2+ maintains the effect and structure of the MLVs. The changes in the lateral pressure of the Curosurf® bilayer revealed that the intercalated BUD between the acyl chains of the surfactant's lipid molecules resides deeper in the hydrophobic region when its content exceeds ~6 wt%. Our studies support the concept of a combined therapy utilising budesonide-enriched Curosurf®.
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Affiliation(s)
- Atoosa Keshavarzi
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, 832 32 Bratislava, Slovakia
| | - Ali Asi Shirazi
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, 832 32 Bratislava, Slovakia
| | - Rastislav Korfanta
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, 832 32 Bratislava, Slovakia
| | - Nina Královič
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, 832 32 Bratislava, Slovakia
| | - Mária Klacsová
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, 832 32 Bratislava, Slovakia
| | | | - José Teixeira
- Laboratoire Léon-Brillouin (LLB), UMR12 CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette CEDEX, France
| | - Sophie Combet
- Laboratoire Léon-Brillouin (LLB), UMR12 CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette CEDEX, France
| | - Daniela Uhríková
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, 832 32 Bratislava, Slovakia
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Cooper A, Girish V, Subramaniam AB. Osmotic Pressure Enables High-Yield Assembly of Giant Vesicles in Solutions of Physiological Ionic Strengths. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:5579-5590. [PMID: 37021722 PMCID: PMC10116648 DOI: 10.1021/acs.langmuir.3c00457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Giant unilamellar vesicles (GUVs) are micrometer-scale minimal cellular mimics that are useful for bottom-up synthetic biology and drug delivery. Unlike assembly in low-salt solutions, assembly of GUVs in solutions with ionic concentrations of 100-150 mM Na/KCl (salty solutions) is challenging. Chemical compounds deposited on the substrate or incorporated into the lipid mixture could assist in the assembly of GUVs. Here, we investigate quantitatively the effects of temperature and chemical identity of six polymeric compounds and one small molecule compound on the molar yields of GUVs composed of three different lipid mixtures using high-resolution confocal microscopy and large data set image analysis. All the polymers moderately increased the yields of GUVs either at 22 or 37 °C, whereas the small molecule compound was ineffective. Low-gelling temperature agarose is the singular compound that consistently produces yields of GUVs of greater than 10%. We propose a free energy model of budding to explain the effects of polymers in assisting the assembly of GUVs. The osmotic pressure exerted on the membranes by the dissolved polymer balances the increased adhesion between the membranes, thus reducing the free energy for bud formation. Data obtained by modulating the ionic strength and ion valency of the solution shows that the evolution of the yield of GUVs supports our model's prediction. In addition, polymer-specific interactions with the substrate and the lipid mixture affects yields. The uncovered mechanistic insights provide a quantitative experimental and theoretical framework to guide future studies. Additionally, this work shows a facile means for obtaining GUVs in solutions of physiological ionic strengths.
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Affiliation(s)
- Alexis Cooper
- Department
of Chemistry and Biochemistry, University
of California, Merced, Merced, California 95343, United States
| | - Vaishnavi Girish
- Department
of Bioengineering, University of California,
Merced, Merced, California 95343, United States
| | - Anand Bala Subramaniam
- Department
of Bioengineering, University of California,
Merced, Merced, California 95343, United States
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5
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Gahan CG, Van Lehn RC, Blackwell HE, Lynn DM. Interactions of Bacterial Quorum Sensing Signals with Model Lipid Membranes: Influence of Membrane Composition on Membrane Remodeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:295-307. [PMID: 36534123 PMCID: PMC10038191 DOI: 10.1021/acs.langmuir.2c02506] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We report the influence of membrane composition on the multiscale remodeling of multicomponent lipid bilayers initiated by contact with the amphiphilic bacterial quorum sensing signal N-(3-oxo)-dodecanoyl-l-homoserine lactone (3-oxo-C12-AHL) and its anionic headgroup hydrolysis product, 3-oxo-C12-HS. We used fluorescence microscopy and quartz crystal microbalance with dissipation (QCM-D) to characterize membrane reformation that occurs when these amphiphiles are placed in contact with supported lipid bilayers (SLBs) composed of (i) 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) containing varying amounts of cholesterol or (ii) mixtures of DOPC and either 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE, a conical zwitterionic lipid) or 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS, a model anionic lipid). In general, we observe these mixed-lipid membranes to undergo remodeling events, including the formation and subsequent collapse of long tubules and the formation of hemispherical caps, upon introduction to biologically relevant concentrations of 3-oxo-C12-AHL and 3-oxo-C12-HS in ways that differ substantially from those observed in single-component DOPC membranes. These differences in bilayer reformation and their associated dynamics can be understood in terms of the influence of membrane composition on the time scales of molecular flip-flop, lipid packing defects, and lipid phase segregation in these materials. The lipid components investigated here are representative of classes of lipids that comprise both naturally occurring cell membranes and many useful synthetic soft materials. These studies thus represent a first step toward understanding the ways in which membrane composition can impact interactions with this important class of bacterial signaling molecules.
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Affiliation(s)
- Curran G. Gahan
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
| | - Reid C. Van Lehn
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
| | - Helen E. Blackwell
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
| | - David M. Lynn
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
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6
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Sule K, Anikovskiy M, Prenner EJ. Lipid Structure Determines the Differential Impact of Single Metal Additions and Binary Mixtures of Manganese, Calcium and Magnesium on Membrane Fluidity and Liposome Size. Int J Mol Sci 2023; 24:ijms24021066. [PMID: 36674581 PMCID: PMC9860990 DOI: 10.3390/ijms24021066] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 12/23/2022] [Accepted: 01/02/2023] [Indexed: 01/08/2023] Open
Abstract
Unilamellar vesicles of the biologically relevant lipids phosphatidic acid (PA) and phosphatidylserine (PS) with fully saturated (DM-) or partly unsaturated (PO-) acyl side chains were exposed to Ca, Mn and Mg in single metal additions; in equimolar mixtures or by sequential additions of one metal at a time. Laurdan generalized polarization measured the membrane fluidity, while dynamic light scattering reported liposome size changes complemented by zeta potential. All metals induced membrane rigidity and increased liposome sizes across all systems. Mn had the strongest effect overall, but Mg was comparable for DMPS. Lipid side chain architecture was important as GP values for binary mixtures were higher than expected from the sum of values for single additions added to POPS but smaller for DMPS. Sequential additions were predominantly different for Ca:Mg mixtures. Mn induced the strongest increase of liposome size in saturated lipids whereas Ca effects dominated unsaturated matrices. Binary additions induced larger sizes than the sum of single additions for POPS, but much lower changes in DMPA. The order of addition was relevant for PS systems. Thus, lipid structure determines metal effects, but their impact is modulated by other ions. Thus, metal effects may differ with the local lipid architecture and metal concentrations within cells.
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Affiliation(s)
- Kevin Sule
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Max Anikovskiy
- Department of Chemistry, Nanoscience Program, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Elmar J. Prenner
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
- Correspondence:
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7
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Dong Y, Fu L, Song J, Zhang S, Li X, Fang W, Cui Q, Gao L. Thermodynamic Driving Forces for Divalent Cations Binding to Zwitterionic Phospholipid Membranes. J Phys Chem Lett 2022; 13:11237-11244. [PMID: 36448843 DOI: 10.1021/acs.jpclett.2c03019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We calculated the free energies for calcium, magnesium, and zinc ions binding to a zwitterionic phospholipid bilayer by using molecular dynamics simulations and the enhanced umbrella sampling technique. By decomposing the free energy into entropic and enthalpic contributions, we found that Ca2+ has the highest binding affinity and that the overall process is endothermic combined with a secondary exothermic process at higher ion concentrations. The relatively low dehydration free energy of Ca2+ allows it to release coordinated water upon binding to the membrane. The dehydrated Ca2+ further coordinates with lipids, resulting in a weaker influence on the water orientation and increased entropy. However, when sufficient Ca2+ ions are adsorbed, the concentrated cation layer induces a positive electrostatic field, which enhances the energy barrier for further ion binding and orients the adjacent water, resulting in decreased entropy. In contrast, binding of Mg2+ and Zn2+ is exothermic and less favored because they remain fully hydrated when interacting with lipids.
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Affiliation(s)
- Yi Dong
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Lei Fu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts02215, United States
| | - Junjie Song
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Shan Zhang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Xiangyuan Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Weihai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
| | - Qiang Cui
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts02215, United States
| | - Lianghui Gao
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing100875, China
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8
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Kurakin S, Ivankov O, Skoi V, Kuklin A, Uhríková D, Kučerka N. Cations Do Not Alter the Membrane Structure of POPC—A Lipid With an Intermediate Area. Front Mol Biosci 2022; 9:926591. [PMID: 35898308 PMCID: PMC9312375 DOI: 10.3389/fmolb.2022.926591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/07/2022] [Indexed: 12/02/2022] Open
Abstract
Combining small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and densitometric measurements, we have studied the interactions of the divalent cations Ca2+ and Mg2+ with the lipid vesicles prepared of a mixed-chain palmitoyl-oleoyl-phosphatidylcholine (POPC) at 25°C. The structural parameters of the POPC bilayer, such as the bilayer thickness, lateral area, and volume per lipid, displayed no changes upon the ion addition at concentrations up to 30 mM and minor changes at > 30 mM Ca2+ and Mg2+, while some decrease in the vesicle radius was observed over the entire concentration range studied. This examination allows us to validate the concept of lipid–ion interactions governed by the area per lipid suggested previously and to propose the mixed mode of those interactions that emerge in the POPC vesicles. We speculate that the average area per POPC lipid that corresponds to the cutoff length of lipid–ion interactions generates an equal but opposite impact on ion bridges and separate lipid–ion pairs. As a result of the dynamic equilibrium, the overall structural properties of bilayers are not affected. As the molecular mechanism proposed is affected by the structural properties of a particular lipid, it might help us to understand the fundamentals of processes occurring in complex multicomponent membrane systems.
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Affiliation(s)
- Sergei Kurakin
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
- Institute of Physics, Kazan Federal University, Kazan, Russia
| | - Oleksandr Ivankov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
| | - Vadim Skoi
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
- Moscow Institute of Physics and Technology, Dolgoprudnyi, Russia
| | - Alexander Kuklin
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
- Moscow Institute of Physics and Technology, Dolgoprudnyi, Russia
| | - Daniela Uhríková
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Bratislava, Slovakia
| | - Norbert Kučerka
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Bratislava, Slovakia
- *Correspondence: Norbert Kučerka,
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9
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Sule K, Prenner EJ. Lipid headgroup and side chain architecture determine manganese-induced dose dependent membrane rigidification and liposome size increase. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2022; 51:205-223. [PMID: 35166865 DOI: 10.1007/s00249-022-01589-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/25/2021] [Accepted: 01/22/2022] [Indexed: 06/14/2023]
Abstract
Metal ion-membrane interactions have gained appreciable attention over the years resulting in increasing investigations into the mode of action of toxic and essential metals. More work has focused on essential ions like Ca or Mg and toxic metals like Cd and Pb, whereas this study investigates the effects of the abundant essential trace metal manganese with model lipid systems by screening zwitterionic and anionic glycerophospholipids. Despite its essentiality, deleterious impact towards cell survival is known under Mn stress. The fluorescent dyes Laurdan and diphenylhexatriene were used to assess changes in membrane fluidity both in the head group and hydrophobic core region of the membrane, respectively. Mn-rigidified membranes composed of the anionic phospholipids, phosphatidic acid, phosphatidylglycerol, cardiolipin, and phosphatidylserine. Strong binding resulted in large shifts of the phase transition temperature. The increase was in the order phosphatidylserine > phosphatidylglycerol > cardiolipin, and in all cases, saturated analogues > mono-unsaturated forms. Dynamic light scattering measurements revealed that Mn caused extensive aggregation of liposomes composed of saturated analogues of phosphatidic acid and phosphatidylserine, whilst the mono-unsaturated analogue had significant membrane swelling. Increased membrane rigidity may interfere with permeability of ions and small molecules, possibly disrupting cellular homeostasis. Moreover, liposome size changes could indicate fusion, which could also be detrimental to cellular transport. Overall, this study provided further understanding into the effects of Mn with biomembranes, whereby the altered membrane properties are consequential to the proper structural and signalling functions of membrane lipids.
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Affiliation(s)
- Kevin Sule
- Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Elmar J Prenner
- Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4, Canada.
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10
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Lipowsky R. Multispherical shapes of vesicles highlight the curvature elasticity of biomembranes. Adv Colloid Interface Sci 2022; 301:102613. [PMID: 35228127 DOI: 10.1016/j.cis.2022.102613] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 01/29/2022] [Accepted: 01/30/2022] [Indexed: 11/01/2022]
Abstract
Giant lipid vesicles form unusual multispherical or "multi-balloon" shapes consisting of several spheres that are connected by membrane necks. Such multispherical shapes have been recently observed when the two sides of the membranes were exposed to different sugar solutions. This sugar asymmetry induced a spontaneous curvature, the sign of which could be reversed by swapping the interior with the exterior solution. Here, previous studies of multispherical shapes are reviewed and extended to develop a comprehensive theory for these shapes. Each multisphere consists of large and small spheres, characterized by two radii, the large-sphere radius, Rl, and the small-sphere radius, Rs. For positive spontaneous curvature, the multisphere can be built up from variable numbers Nl and Ns of large and small spheres. In addition, multispheres consisting of N*=Nl+Ns equally sized spheres are also possible and provide examples for constant-mean-curvature surfaces. For negative spontaneous curvature, all multispheres consist of one large sphere that encloses a variable number Ns of small spheres. These general features of multispheres arise from two basic properties of curvature elasticity: the local shape equation for spherical membrane segments and the stability conditions for closed membrane necks. In addition, the (Nl+Ns)-multispheres can form several (Nl+Ns)-patterns that differ in the way, in which the spheres are mutually connected. These patterns may involve multispherical junctions consisting of individual spheres that are connected to more than two neighboring spheres. The geometry of the multispheres is governed by two polynomial equations which imply that (Nl+Ns)-multispheres can only be formed within a certain restricted range of vesicle volumes. Each (Nl+Ns)-pattern can be characterized by a certain stability regime that depends both on the stability of the closed necks and on the multispherical geometry. Interesting and challenging topics for future studies include the response of multispheres to locally applied external forces, membrane fusion between spheres to create multispherical shapes of higher-genus topology, and the enlarged morphological complexity of multispheres arising from lipid phase separation and intramembrane domains.
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11
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Calcium mediated DNA binding in non-lamellar structures formed by DOPG/glycerol monooleate. Chem Phys Lipids 2021; 239:105118. [PMID: 34280362 DOI: 10.1016/j.chemphyslip.2021.105118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/28/2021] [Accepted: 07/14/2021] [Indexed: 11/21/2022]
Abstract
In order to test an encapsulation method of short fragmented DNA (∼ 20-300 bp), we study the solubilisation in 150 mM solution of NaCl of a cubic phase formed by glycerol monooleate (GMO) with negatively charged dioleoylphosphatidylglycerol (DOPG) up to the level of unilamellar vesicles and, subsequently, the restoration of the cubic phase using Ca2+ cations. We performed small angle X-ray and neutron scattering (SAXS and SANS) to follow structural changes in DOPG/GMO mixtures induced by increasing DOPG content. The cubic phase (Pn3m space group) is preserved up to ∼ 11 mol% of DOPG in DOPG/GMO. Above 20 mol%, the SANS curves are typical of unilamellar vesicles. The thickness of the DOPG/GMO lipid bilayer (dL) decreases slightly with increasing fraction of DOPG. The addition of 15 mM of CaCl2 solution shields the electrostatic repulsions of DOPG molecules, increases slightly dL and restores the cubic structures in the mixtures up to ∼ 37 mol% of DOPG. Zeta potential shows negative surface charge. The analysis of the data provides the radius of the water nano-channels of the formed non-lamellar structures. We discuss their dimensions with respect to DNA binding. In addition, Ca2+ mediates DNA - DOPG/GMO binding. The formed hexagonal phase, HII, binds less of DNA in comparison with cubic phases (∼ 6 wt% and ∼ 20 wt% of the total amount, respectively). The studied system can be utilized as anionic QII delivery vector for genetic material.
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