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Alobaid AA, Skoda MWA, Harris LK, Campbell RA. Translational use of homing peptides: Tumor and placental targeting. J Colloid Interface Sci 2024; 662:1033-1043. [PMID: 38387365 DOI: 10.1016/j.jcis.2024.02.103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 01/30/2024] [Accepted: 02/12/2024] [Indexed: 02/24/2024]
Abstract
HYPOTHESIS Tissue-specific homing peptides have been shown to improve chemotherapeutic efficacy due to their trophism for tumor cells. Other sequences that selectively home to the placenta are providing new and safer therapeutics to treat complications in pregnancy. Our hypothesis is that the placental homing peptide RSGVAKS (RSG) may have binding affinity to cancer cells, and that insight can be gained into the binding mechanisms of RSG and the tumor homing peptide CGKRK to model membranes that mimic the primary lipid compositions of the respective cells. EXPERIMENTS Following cell culture studies on the binding efficacy of the peptides on a breast cancer cell line, a systematic translational characterization is delivered using ellipsometry, Brewster angle microscopy and neutron reflectometry of the extents, structures, and dynamics of the interactions of the peptides with the model membranes on a Langmuir trough. FINDINGS We start by revealing that RSG does indeed have binding affinity to breast cancer cells. The peptide is then shown to exhibit stronger interactions and greater penetration than CGKRK into both model membranes, combined with greater disruption to the lipid component. RSG also forms aggregates bound to the model membranes, yet both peptides bind to a greater extent to the placental than cancer model membranes. The results demonstrate the potential for varying local reservoirs of peptide within cell membranes that may influence receptor binding. The innovative nature of our findings motivates the urgent need for more studies involving multifaceted experimental platforms to explore the use of specific peptide sequences to home to different cellular targets.
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Affiliation(s)
- Abdulaziz A Alobaid
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom; Department of Pharmaceutics, Faculty of Pharmacy, Kuwait University, P.O. Box 24923, Safat 13110, Kuwait
| | - Maximilian W A Skoda
- ISIS Neutron & Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - Lynda K Harris
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom; Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9WL, United Kingdom; St Mary's Hospital, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester M13 9WL, United Kingdom; Olson Center for Women's Health, University of Nebraska Medical Center, Omaha, NE 68198, United States.
| | - Richard A Campbell
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom.
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Li S, Pilkington GA, Mehler F, Hammond OS, Boudier A, Vorobiev A, Glavatskih S, Rutland MW. Tuneable interphase transitions in ionic liquid/carrier systems via voltage control. J Colloid Interface Sci 2023; 652:1240-1249. [PMID: 37657223 DOI: 10.1016/j.jcis.2023.08.111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/09/2023] [Accepted: 08/18/2023] [Indexed: 09/03/2023]
Abstract
The structure and interaction of ionic liquids (ILs) influence their interfacial composition, and their arrangement (i.e., electric double-layer (EDL) structure), can be controlled by an electric field. Here, we employed a quartz crystal microbalance (QCM) to study the electrical response of two non-halogenated phosphonium orthoborate ILs, dissolved in a polar solvent at the interface. The response is influenced by the applied voltage, the structure of the ions, and the solvent polarizability. One IL showed anomalous electro-responsivity, suggesting a self-assembly bilayer structure of the IL cation at the gold interface, which transitions to a typical EDL structure at higher positive potential. Neutron reflectivity (NR) confirmed this interfacial structuring and compositional changes at the electrified gold surface. A cation-dominated self-assembly structure is observed for negative and neutral voltages, which abruptly transitions to an anion-rich interfacial layer at positive voltages. An interphase transition explains the electro-responsive behaviour of self-assembling IL/carrier systems, pertinent for ILs in advanced tribological and electrochemical contexts.
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Affiliation(s)
- Sichao Li
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Filip Mehler
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Oliver S Hammond
- Department of Materials and Environmental Chemistry, Stockholm University, SE-114 18 Stockholm, Sweden; Department of Biological and Chemical Engineering, Aarhus University, Aarhus C 8000 Denmark
| | - Anthony Boudier
- Department of Materials and Environmental Chemistry, Stockholm University, SE-114 18 Stockholm, Sweden
| | - Alexei Vorobiev
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, SE-751 20 Uppsala, Sweden
| | - Sergei Glavatskih
- System and Component Design, Department of Engineering Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia; Department of Electromechanical, Systems and Metal Engineering, Ghent University, B-9052 Ghent, Belgium
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia; Bioeconomy and Health Department Materials and Surface Design, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden; Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, 69134 Ecully Cedex, France.
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Tucker IM, Burley A, Petkova RE, Hosking SL, Penfold J, Thomas RK, Li PX, Webster JRP, Welbourn R, Doutch J. Adsorption and self-assembly properties of the plant based biosurfactant, Glycyrrhizic acid. J Colloid Interface Sci 2021; 598:444-54. [PMID: 33930748 DOI: 10.1016/j.jcis.2021.03.101] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 11/23/2022]
Abstract
There is an increased interest in the use of natural surfactant as replacements for synthetic surfactants due to their biosustainable and biocompatible properties. A category of natural surfactants which are attracting much current interest is the triterpenoid saponins; surface active components found extensively in a wide range of plant species. A wide range of different saponin structures exist, depending upon the plant species they are extracted from; but regardless of the variation in structural details they are all highly surface active glycosides. Greater exploitation and application requires a characterisation and understanding of their basic adsorption and self-assembly properties. HYPOTHESIS Glycyrrhizic acid, extracted from Licorice root, is a monodesmosidic triterpenoid saponin. It is widely used in cosmetic and pharmaceutical applications due to its anti-inflammatory properties, and is an ingredient in foods as a sweetener additive. It has an additional attraction due to its gel forming properties at relatively low concentrations. Although it has attracted much recent attention, many of its basic surface active characteristics, adsorption and self-assembly, remain relatively unexplored. How the structure of the Glycyrrhizic acid saponin affects its surface active properties and the impact of gelation on these properties are important considerations, and to investigate these are the focus of the study. EXPERIMENTS In this paper the adsorption properties at the air-water interface and the self-assembly in solution have been investigated using by neutron reflectivity and small angle neutron scattering; in non-gelling and gelling conditions. FINDINGS The adsorption isotherm is determined in water and in the presence of gelling additives, and compared with the adsorption behaviour of other saponins. Gelation has minimal impact on the adsorption; apart from producing a rougher surface with a surface texture on a macroscopic length scale. Globular micelles are formed in aqueous solution with modest anisotropy, and are compared with the structure of other saponin micelles. The addition of gelling agents results in only minimal micelle growth, and the solutions remain isotropic under applied shear flow.
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Slastanova A, Campbell RA, Snow T, Mould E, Li P, Welbourn RJL, Chen M, Robles E, Briscoe WH. Synergy, competition, and the "hanging" polymer layer: Interactions between a neutral amphiphilic 'tardigrade' comb co-polymer with an anionic surfactant at the air-water interface. J Colloid Interface Sci 2020; 561:181-94. [PMID: 31830734 DOI: 10.1016/j.jcis.2019.11.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/03/2019] [Accepted: 11/05/2019] [Indexed: 12/21/2022]
Abstract
Understanding the structure of polymer/surfactant mixtures at the air-water interface is of fundamental importance and also of relevance to a variety of practical applications. Here, the complexation between a neutral 'tardigrade' comb co-polymer (consisting of a hydrophilic polyethylene glycol backbone with hydrophobic polyvinyl acetate grafts, PEG-g-PVAc) with an anionic surfactant (sodium dodecyl sulfate, SDS) at the air-water interface has been studied. Contrast-matched neutron reflectivity (NR) complemented by surface tension measurements allowed elucidation of the interfacial composition and structure of these mixed systems, as well as providing physical insights into the polymer/surfactant interactions at the air-water interface. For both polymer concentrations studied, below and above its critical aggregation concentration, cac, (0.2 cac and 2 cac, corresponding to 0.0002 wt% or 0.013 mM and 0.002 wt% or 0.13 mM respectively), we observed a synergistic cooperative behaviour at low surfactant concentrations with a 1-2 nm mixed interfacial layer; a competitive adsorption behaviour at higher surfactant concentrations was observed where the polymer was depleted from the air-water interface, with an overall interfacial layer thickness ~1.6 nm independent of the polymer concentration. The weakly associated polymer layer "hanging" proximally to the interface, however, played a role in enhancing foam stability, thus was relevant to the detergency efficacy in such polymer/surfactant mixtures in industrial formulations.
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Sun H, Zielinska K, Resmini M, Zarbakhsh A. Interactions of NIPAM nanogels with model lipid multi-bilayers: A neutron reflectivity study. J Colloid Interface Sci 2019; 536:598-608. [PMID: 30390585 DOI: 10.1016/j.jcis.2018.10.086] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/22/2018] [Accepted: 10/27/2018] [Indexed: 10/28/2022]
Abstract
In dermal drug delivery, the influence of the chemical structure of the carriers on their penetration mechanisms is not yet fully understood. This is a key requirement in order to design highly efficient delivery systems. In this study, neutron reflectivity is used to provide insights into the interactions between thermoresponsive N-isopropylacrylamide based nanogels, cross-linked with 10%, 20% and 30% N,N'-methylenebisacrylamide, and skin lipid multi-bilayers models. Ceramide lipid multi-bilayers and ceramide/cholesterol/behenic acid mixed lipid multi-bilayers were used for this work. The results indicated that in both multi-bilayers the lipids were depleted by the nanogels mainly through hydrophobic interactions. The ability of nanogels to associate with skin lipids to form water-dispersible complexes was found to be a function of the percentage cross-linker. An enhanced depletion of lipids was further observed in the presence of benzyl alcohol, a well-known skin penetration enhancer.
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Affiliation(s)
- Huihui Sun
- Department of Chemistry, Queen Mary, University of London, Joseph Priestley Building, Mile End Road, London E1 4NS, United Kingdom
| | - Katarzyna Zielinska
- Department of Chemistry, Queen Mary, University of London, Joseph Priestley Building, Mile End Road, London E1 4NS, United Kingdom
| | - Marina Resmini
- Department of Chemistry, Queen Mary, University of London, Joseph Priestley Building, Mile End Road, London E1 4NS, United Kingdom.
| | - Ali Zarbakhsh
- Department of Chemistry, Queen Mary, University of London, Joseph Priestley Building, Mile End Road, London E1 4NS, United Kingdom.
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Vanegas JM, Heinrich F, Rogers DM, Carson BD, La Bauve S, Vernon BC, Akgun B, Satija S, Zheng A, Kielian M, Rempe SB, Kent MS. Insertion of Dengue E into lipid bilayers studied by neutron reflectivity and molecular dynamics simulations. Biochim Biophys Acta Biomembr 2018; 1860:1216-1230. [PMID: 29447917 DOI: 10.1016/j.bbamem.2018.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/08/2018] [Accepted: 02/09/2018] [Indexed: 02/01/2023]
Abstract
The envelope (E) protein of Dengue virus rearranges to a trimeric hairpin to mediate fusion of the viral and target membranes, which is essential for infectivity. Insertion of E into the target membrane serves to anchor E and possibly also to disrupt local order within the membrane. Both aspects are likely to be affected by the depth of insertion, orientation of the trimer with respect to the membrane normal, and the interactions that form between trimer and membrane. In the present work, we resolved the depth of insertion, the tilt angle, and the fundamental interactions for the soluble portion of Dengue E trimers (sE) associated with planar lipid bilayer membranes of various combinations of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-glycerol (POPG), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), and cholesterol (CHOL) by neutron reflectivity (NR) and by molecular dynamics (MD) simulations. The results show that the tip of E containing the fusion loop (FL) is located at the interface of the headgroups and acyl chains of the outer leaflet of the lipid bilayers, in good agreement with prior predictions. The results also indicate that E tilts with respect to the membrane normal upon insertion, promoted by either the anionic lipid POPG or CHOL. The simulations show that tilting of the protein correlates with hydrogen bond formation between lysines and arginines located on the sides of the trimer close to the tip (K246, K247, and R73) and nearby lipid headgroups. These hydrogen bonds provide a major contribution to the membrane anchoring and may help to destabilize the target membrane.
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Affiliation(s)
- Juan M Vanegas
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Frank Heinrich
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD, United States; Department of Physics, Carnegie Mellon University, Pittsburgh, PA, United States
| | - David M Rogers
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Bryan D Carson
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Sadie La Bauve
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Briana C Vernon
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Bulent Akgun
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD, United States
| | - Sushil Satija
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD, United States
| | - Aihua Zheng
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Margaret Kielian
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Susan B Rempe
- Sandia National Laboratories, Albuquerque, NM, United States
| | - Michael S Kent
- Sandia National Laboratories, Albuquerque, NM, United States.
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7
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Mazzer AR, Clifton LA, Perevozchikova T, Butler PD, Roberts CJ, Bracewell DG. Neutron reflectivity measurement of protein A-antibody complex at the solid-liquid interface. J Chromatogr A 2017; 1499:118-131. [PMID: 28410804 PMCID: PMC5408906 DOI: 10.1016/j.chroma.2017.03.084] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/15/2017] [Accepted: 03/30/2017] [Indexed: 01/05/2023]
Abstract
The orientation of IgG4 adsorbed at the solid-liquid interface was probed. A chromatography resin was mimicked by attaching protein A to a silica surface. Neutron reflectivity was used to measure protein A and adsorbed IgG structures. Protein A-modified silica was blocked with either BSA or PEG before IgG adsorption. Adsorbed IgG extended up to 230 Å from the surface, depending on blocking strategy.
Chromatography is a ubiquitous unit operation in the purification of biopharmaceuticals yet few studies have addressed the biophysical characterisation of proteins at the solution-resin interface. Chromatography and other adsorption and desorption processes have been shown to induce protein aggregation which is undesirable in biopharmaceutical products. In order to advance understanding of how adsorption processes might impact protein stability, neutron reflectivity was used to characterise the structure of adsorbed immunoglobulin G (IgG) on model surfaces. In the first model system, IgG was adsorbed directly to silica and demonstrated a side-on orientation with high surface contact. A maximum dimension of 60 Å in the surface normal direction and high density surface coverage were observed under pH 4.1 conditions. In chromatography buffers, pH was found to influence IgG packing density and orientation at the solid-liquid interface. In the second model system, which was designed to mimic an affinity chromatography surface, protein A was attached to a silica surface to produce a configuration representative of a porous glass chromatography resin. Interfacial structure was probed during sequential stages from ligand attachment, through to IgG binding and elution. Adsorbed IgG structures extended up to 250 Å away from the surface and showed dependence on surface blocking strategies. The data was suggestive of two IgG molecules bound to protein A with a somewhat skewed orientation and close proximity to the silica surface. The findings provide insight into the orientation of adsorbed antibody structures under conditions encountered during chromatographic separations.
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Affiliation(s)
- Alice R Mazzer
- Dept. Biochemical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Luke A Clifton
- ISIS, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0QX, UK
| | - Tatiana Perevozchikova
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA
| | - Paul D Butler
- National Institute of Standards and Technology, 100 Bureau Drive, Bldg. 235, Gaithersburg, MD 20899-8562, USA
| | - Christopher J Roberts
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA
| | - Daniel G Bracewell
- Dept. Biochemical Engineering, University College London, Gower Street, London, WC1E 6BT, UK.
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Isaksson S, Watkins EB, Browning KL, Kjellerup Lind T, Cárdenas M, Hedfalk K, Höök F, Andersson M. Protein-Containing Lipid Bilayers Intercalated with Size-Matched Mesoporous Silica Thin Films. Nano Lett 2017; 17:476-485. [PMID: 28073257 DOI: 10.1021/acs.nanolett.6b04493] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Proteins are key components in a multitude of biological processes, of which the functions carried out by transmembrane (membrane-spanning) proteins are especially demanding for investigations. This is because this class of protein needs to be incorporated into a lipid bilayer representing its native environment, and in addition, many experimental conditions also require a solid support for stabilization and analytical purposes. The solid support substrate may, however, limit the protein functionality due to protein-material interactions and a lack of physical space. We have in this work tailored the pore size and pore ordering of a mesoporous silica thin film to match the native cell-membrane arrangement of the transmembrane protein human aquaporin 4 (hAQP4). Using neutron reflectivity (NR), we provide evidence of how substrate pores host the bulky water-soluble domain of hAQP4, which is shown to extend 7.2 nm into the pores of the substrate. Complementary surface analytical tools, including quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescence microscopy, revealed successful protein-containing supported lipid bilayer (pSLB) formation on mesoporous silica substrates, whereas pSLB formation was hampered on nonporous silica. Additionally, electron microscopy (TEM and SEM), light scattering (DLS and stopped-flow), and small-angle X-ray scattering (SAXS) were employed to provide a comprehensive characterization of this novel hybrid organic-inorganic interface, the tailoring of which is likely to be generally applicable to improve the function and stability of a broad range of membrane proteins containing water-soluble domains.
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Affiliation(s)
- Simon Isaksson
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-41296 Gothenburg, Sweden
| | - Erik B Watkins
- Materials Physics and Application Division, MPA-11, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | | | - Tania Kjellerup Lind
- Department of Biomedical Sciences and Biofilm-The Research Center for Biointerfaces, Health & Society, Malmo University , SE-20500 Malmo, Sweden
| | - Marité Cárdenas
- Department of Biomedical Sciences and Biofilm-The Research Center for Biointerfaces, Health & Society, Malmo University , SE-20500 Malmo, Sweden
| | - Kristina Hedfalk
- Department of Chemistry and Molecular Biology, University of Gothenburg , SE-40530 Gothenburg, Sweden
| | - Fredrik Höök
- Department of Applied Physics, Chalmers University of Technology , SE-41296 Gothenburg, Sweden
| | - Martin Andersson
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-41296 Gothenburg, Sweden
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O'Neil L, Andenoro K, Pagano I, Carroll L, Langer L, Dell Z, Perera D, Treece BW, Heinrich F, Lösche M, Nagle JF, Tristram-Nagle S. HIV-1 matrix-31 membrane binding peptide interacts differently with membranes containing PS vs. PI(4,5)P 2. Biochim Biophys Acta 2016; 1858:3071-3081. [PMID: 27641491 DOI: 10.1016/j.bbamem.2016.09.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 12/27/2022]
Abstract
Efficient assembly of HIV-1 at the plasma membrane (PM) of the T-cell specifically requires PI(4,5)P2. It was previously shown that a highly basic region (HBR) of the matrix protein (MA) on the Gag precursor polyprotein Pr55Gag is required for membrane association. MA is N-terminally myristoylated, which enhances its affinity to membranes. In this work we used X-ray scattering and neutron reflectivity to determine how the physical properties and structure of lipid bilayers respond to the addition of binding domain peptides, either in the myristoylated form (MA31myr) or without the myristoyl group (MA31). Neutron reflectivity measurements showed the peptides predominantly located in the hydrocarbon interior. Diffuse X-ray scattering showed differences in membrane properties upon addition of peptides and the direction of the changes depended on lipid composition. The PI(4,5)P2-containing bilayers softened, thinned and became less ordered as peptide concentration increased. In contrast, POPS-containing bilayers with equivalent net charge first stiffened, thickened and became more ordered with increasing peptide concentration. As softening the host cell's PM upon contact with the protein lowers the free energy for membrane restructuring, thereby potentially facilitating budding of viral particles, our results suggest that the role of PI(4,5)P2 in viral assembly goes beyond specific stereochemical membrane binding. These studies reinforce the importance of lipids in virology.
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Affiliation(s)
- Lauren O'Neil
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Kathryn Andenoro
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Isabella Pagano
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Laura Carroll
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Leah Langer
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Zachary Dell
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Davina Perera
- Biomedical Engineering, Douglass College, Rutgers University, New Brunswick, NJ 08901, United States
| | - Bradley W Treece
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Frank Heinrich
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States; National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD 20899, United States
| | - Mathias Lösche
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States; National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD 20899, United States; Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - John F Nagle
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Stephanie Tristram-Nagle
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
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Abstract
The principles of neutron reflectivity and its application as a tool to provide structural information at the (sub-) molecular unit length scale from models for bacterial membranes are described. The model membranes can take the form of a monolayer for a single leaflet spread at the air/water interface, or bilayers of increasing complexity at the solid/liquid interface. Solid-supported bilayers constrain the bilayer to 2D but can be used to characterize interactions with antimicrobial peptides and benchmark high throughput lab-based techniques. Floating bilayers allow for membrane fluctuations, making the phase behaviour more representative of native membranes. Bilayers of varying levels of compositional accuracy can now be constructed, facilitating studies with aims that range from characterizing the fundamental physical interactions, through to the characterization of accurate mimetics for the inner and outer membranes of Gram-negative bacteria. Studies of the interactions of antimicrobial peptides with monolayer and bilayer models for the inner and outer membranes have revealed information about the molecular control of the outer membrane permeability, and the mode of interaction of antimicrobials with both inner and outer membranes.
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Affiliation(s)
- Robert D Barker
- Institut Laue-Langevin, 71 Avenue Des Martyrs, CS 20156, 38042, Grenoble Cedex 9, France.,School of Science and Engineering, University of Dundee, James Clerk Maxwell Building, The King's Buildings, Peter Guthrie Tait Road, Dundee, DD1 4HN, UK
| | - Laura E McKinley
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, The King's Buildings, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, Scotland
| | - Simon Titmuss
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, The King's Buildings, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, Scotland.
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11
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Koehler R, Steitz R, von Klitzing R. About different types of water in swollen polyelectrolyte multilayers. Adv Colloid Interface Sci 2014; 207:325-31. [PMID: 24548598 DOI: 10.1016/j.cis.2013.12.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 11/29/2013] [Accepted: 12/19/2013] [Indexed: 11/29/2022]
Abstract
The review addresses swelling of polyelectrolyte multilayers in water. Different models for the determination of the water content are compared. It is clearly shown that voids under dry conditions present cavities for water which contribute to the water content of the multilayer in the swollen state. This so-called "void water" does not lead to any changes in thickness but in scattering length density during swelling. The "swelling water" leads to both changes in scattering length density and in thickness. Depending on the preparation conditions like the type polymers, polymer charge density, ionic strength and type of salt the ratio of "void water" differs between 1 and 15 vol.% while the amount of "swelling water" is of several ten's of vol.%.
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Affiliation(s)
- Ralf Koehler
- Helmholtz-Zentrum, Lise-Meitner Campus, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Roland Steitz
- Helmholtz-Zentrum, Lise-Meitner Campus, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Regine von Klitzing
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Tech-nische Universität Berlin, Strasse des 17. Juni 124, D-10623 Berlin, Germany.
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