1
|
Parsons ES, Liu F, Kaushik A, Lee A, Schuetz J, Dunham D, Seastedt H, Ogulur I, Heider A, Tan G, Shah A, Cao S, Smith E, Kost L, Acharya S, Prunicki M, Rothenberg M, Sindher S, Leib R, Akdis CA, Nadeau K, Lejeune S. Detection of gut and mucosal peptides through TOMAHAQ in healthy individuals. Allergy 2023. [PMID: 36872560 DOI: 10.1111/all.15698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 02/13/2023] [Accepted: 02/28/2023] [Indexed: 03/07/2023]
Affiliation(s)
- E S Parsons
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - F Liu
- Mass Spectrometry Center, Stanford University, Palo Alto, California, USA
| | - A Kaushik
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - A Lee
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - J Schuetz
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - D Dunham
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - H Seastedt
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - I Ogulur
- Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich, Davos, Switzerland
| | - A Heider
- Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich, Davos, Switzerland
| | - G Tan
- Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich, Davos, Switzerland
| | - A Shah
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - S Cao
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - E Smith
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - L Kost
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - S Acharya
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - M Prunicki
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA
| | - M Rothenberg
- Department of Pediatrics, Department of Allergy and Immunology, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - S Sindher
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, Stanford University, Stanford, California, USA
| | - R Leib
- Mass Spectrometry Center, Stanford University, Palo Alto, California, USA
| | - C A Akdis
- Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich, Davos, Switzerland
| | - K Nadeau
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA.,Department of Environmental Health Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - S Lejeune
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Palo Alto, California, USA.,INSERM U1019, CNRS UMR 9017, Center for infection and immunity of Lille (CIIL), Univ. Lille, CHU Lille, Institut Pasteur de Lille, Lille, France
| |
Collapse
|
2
|
Hammond K, Benn G, Bennett I, Parsons ES, Ryadnov MG, Hoogenboom BW, Pyne ALB. Imaging the Effects of Peptide Materials on Phospholipid Membranes by Atomic Force Microscopy. Methods Mol Biol 2021; 2208:225-235. [PMID: 32856266 DOI: 10.1007/978-1-0716-0928-6_15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recent advances in biomolecular design require accurate measurements performed in native or near-native environments in real time. Atomic force microscopy (AFM) is a powerful tool to observe the dynamics of biologically relevant processes at aqueous interfaces with high spatial resolution. Here, we describe imaging protocols to characterize the effects of peptide materials on phospholipid membranes in solution by AFM. These protocols can be used to determine the mechanism and kinetics of membrane-associated activities at the nanoscale.
Collapse
Affiliation(s)
- Katharine Hammond
- London Centre for Nanotechnology, University College London, London, UK
- National Physical Laboratory, Teddington, UK
- Department of Physics and Astronomy, University College London, London, UK
| | - Georgina Benn
- London Centre for Nanotechnology, University College London, London, UK
- National Physical Laboratory, Teddington, UK
- Institute of Structural and Molecular Biology, University College London, London, UK
| | - Isabel Bennett
- London Centre for Nanotechnology, University College London, London, UK
| | - Edward S Parsons
- London Centre for Nanotechnology, University College London, London, UK
| | | | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London, UK
- Institute of Structural and Molecular Biology, University College London, London, UK
- Department of Physics and Astronomy, University College London, London, UK
| | - Alice L B Pyne
- London Centre for Nanotechnology, University College London, London, UK.
- Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK.
| |
Collapse
|
3
|
Shah NR, Voisin TB, Parsons ES, Boyd CM, Hoogenboom BW, Bubeck D. Structural basis for tuning activity and membrane specificity of bacterial cytolysins. Nat Commun 2020; 11:5818. [PMID: 33199689 PMCID: PMC7669874 DOI: 10.1038/s41467-020-19482-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/14/2020] [Indexed: 11/25/2022] Open
Abstract
Cholesterol-dependent cytolysins (CDCs) are pore-forming proteins that serve as major virulence factors for pathogenic bacteria. They target eukaryotic cells using different mechanisms, but all require the presence of cholesterol to pierce lipid bilayers. How CDCs use cholesterol to selectively lyse cells is essential for understanding virulence strategies of several pathogenic bacteria, and for repurposing CDCs to kill new cellular targets. Here we address that question by trapping an early state of pore formation for the CDC intermedilysin, bound to the human immune receptor CD59 in a nanodisc model membrane. Our cryo electron microscopy map reveals structural transitions required for oligomerization, which include the lateral movement of a key amphipathic helix. We demonstrate that the charge of this helix is crucial for tuning lytic activity of CDCs. Furthermore, we discover modifications that overcome the requirement of cholesterol for membrane rupture, which may facilitate engineering the target-cell specificity of pore-forming proteins.
Collapse
Affiliation(s)
- Nita R Shah
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Tomas B Voisin
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Edward S Parsons
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Courtney M Boyd
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK.
| |
Collapse
|
4
|
Suthar J, Parsons ES, Hoogenboom BW, Williams GR, Guldin S. Acoustic Immunosensing of Exosomes Using a Quartz Crystal Microbalance with Dissipation Monitoring. Anal Chem 2020; 92:4082-4093. [PMID: 31995983 PMCID: PMC7145312 DOI: 10.1021/acs.analchem.9b05736] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 01/30/2020] [Indexed: 12/12/2022]
Abstract
Exosomes are endocytic lipid-membrane bound bodies with the potential to be used as biomarkers in cancer and neurodegenerative disease. The limitations and scarcity of current exosome characterization approaches have led to a growing demand for translational techniques, capable of determining their molecular composition and physical properties in physiological fluids. Here, we investigate label-free immunosensing, using a quartz crystal microbalance with dissipation monitoring (QCM-D), to detect exosomes by exploiting their surface protein profile. Exosomes expressing the transmembrane protein CD63 were isolated by size-exclusion chromatography from cell culture media. QCM-D sensors functionalized with anti-CD63 antibodies formed a direct immunoassay toward CD63-positive exosomes in 75% v/v serum, exhibiting a limit-of-detection of 2.9 × 108 and 1.4 × 108 exosome sized particles (ESPs)/mL for frequency and dissipation response, respectively, i.e., clinically relevant concentrations. Our proof-of-concept findings support the adoption of dual-mode acoustic analysis of exosomes, leveraging both frequency and dissipation monitoring for use in bioanalytical characterization.
Collapse
Affiliation(s)
- Jugal Suthar
- UCL
School of Pharmacy, University College London, 29-39 Brunswick Square, Bloomsbury, London, WC1N 1AX, United Kingdom
- Department
of Chemical Engineering, University College
London, Torrington Place, London, WC1E 7JE, United Kingdom
| | - Edward S. Parsons
- London
Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH, United Kingdom
| | - Bart W. Hoogenboom
- London
Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH, United Kingdom
- Department
of Physics and Astronomy, University College
London, Gower Street, London, WC1E 6BT, United Kingdom
| | - Gareth R. Williams
- UCL
School of Pharmacy, University College London, 29-39 Brunswick Square, Bloomsbury, London, WC1N 1AX, United Kingdom
| | - Stefan Guldin
- Department
of Chemical Engineering, University College
London, Torrington Place, London, WC1E 7JE, United Kingdom
| |
Collapse
|
5
|
Parsons ES, Stanley GJ, Pyne ALB, Hodel AW, Nievergelt AP, Menny A, Yon AR, Rowley A, Richter RP, Fantner GE, Bubeck D, Hoogenboom BW. Single-molecule kinetics of pore assembly by the membrane attack complex. Nat Commun 2019; 10:2066. [PMID: 31061395 PMCID: PMC6502846 DOI: 10.1038/s41467-019-10058-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/12/2019] [Indexed: 12/24/2022] Open
Abstract
The membrane attack complex (MAC) is a hetero-oligomeric protein assembly that kills pathogens by perforating their cell envelopes. The MAC is formed by sequential assembly of soluble complement proteins C5b, C6, C7, C8 and C9, but little is known about the rate-limiting steps in this process. Here, we use rapid atomic force microscopy (AFM) imaging to show that MAC proteins oligomerize within the membrane, unlike structurally homologous bacterial pore-forming toxins. C5b-7 interacts with the lipid bilayer prior to recruiting C8. We discover that incorporation of the first C9 is the kinetic bottleneck of MAC formation, after which rapid C9 oligomerization completes the pore. This defines the kinetic basis for MAC assembly and provides insight into how human cells are protected from bystander damage by the cell surface receptor CD59, which is offered a maximum temporal window to halt the assembly at the point of C9 insertion.
Collapse
Affiliation(s)
- Edward S Parsons
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.
| | - George J Stanley
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Alice L B Pyne
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - Adrian W Hodel
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Adrian P Nievergelt
- Laboratory for Bio- and Nano-Instrumentation, Swiss Federal Institute of Technology Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Anaïs Menny
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Alexander R Yon
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Ashlea Rowley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Ralf P Richter
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- School of Physics and Astronomy, Faculty of Mathematics and Physical Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Georg E Fantner
- Laboratory for Bio- and Nano-Instrumentation, Swiss Federal Institute of Technology Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Doryen Bubeck
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK.
- Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK.
| |
Collapse
|
6
|
Heesterbeek DA, Bardoel BW, Parsons ES, Bennett I, Ruyken M, Doorduijn DJ, Gorham RD, Berends ET, Pyne AL, Hoogenboom BW, Rooijakkers SH. Bacterial killing by complement requires membrane attack complex formation via surface-bound C5 convertases. EMBO J 2019; 38:embj.201899852. [PMID: 30643019 PMCID: PMC6376327 DOI: 10.15252/embj.201899852] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 12/05/2018] [Accepted: 12/14/2018] [Indexed: 12/16/2022] Open
Abstract
The immune system kills bacteria by the formation of lytic membrane attack complexes (MACs), triggered when complement enzymes cleave C5. At present, it is not understood how the MAC perturbs the composite cell envelope of Gram-negative bacteria. Here, we show that the role of C5 convertase enzymes in MAC assembly extends beyond the cleavage of C5 into the MAC precursor C5b. Although purified MAC complexes generated from preassembled C5b6 perforate artificial lipid membranes and mammalian cells, these components lack bactericidal activity. In order to permeabilize both the bacterial outer and inner membrane and thus kill a bacterium, MACs need to be assembled locally by the C5 convertase enzymes. Our data indicate that C5b6 rapidly loses the capacity to form bactericidal pores; therefore, bacterial killing requires both in situ conversion of C5 and immediate insertion of C5b67 into the membrane. Using flow cytometry and atomic force microscopy, we show that local assembly of C5b6 at the bacterial surface is required for the efficient insertion of MAC pores into bacterial membranes. These studies provide basic molecular insights into MAC assembly and bacterial killing by the immune system.
Collapse
Affiliation(s)
- Dani Ac Heesterbeek
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Bart W Bardoel
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Edward S Parsons
- London Centre for Nanotechnology, University College London, London, UK
| | - Isabel Bennett
- London Centre for Nanotechnology, University College London, London, UK
| | - Maartje Ruyken
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Dennis J Doorduijn
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Ronald D Gorham
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Evelien Tm Berends
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Alice Lb Pyne
- London Centre for Nanotechnology, University College London, London, UK
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London, UK.,Department of Physics and Astronomy, University College London, London, UK
| | - Suzan Hm Rooijakkers
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| |
Collapse
|
7
|
Boyd CM, Parsons ES, Smith RAG, Seddon JM, Ces O, Bubeck D. Disentangling the roles of cholesterol and CD59 in intermedilysin pore formation. Sci Rep 2016; 6:38446. [PMID: 27910935 PMCID: PMC5133593 DOI: 10.1038/srep38446] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 11/08/2016] [Indexed: 01/08/2023] Open
Abstract
The plasma membrane provides an essential barrier, shielding a cell from the pressures of its external environment. Pore-forming proteins, deployed by both hosts and pathogens alike, breach this barrier to lyse target cells. Intermedilysin is a cholesterol-dependent cytolysin that requires the human immune receptor CD59, in addition to cholesterol, to form giant β-barrel pores in host membranes. Here we integrate biochemical assays with electron microscopy and atomic force microscopy to distinguish the roles of these two receptors in mediating structural transitions of pore formation. CD59 is required for the specific coordination of intermedilysin (ILY) monomers and for triggering collapse of an oligomeric prepore. Movement of Domain 2 with respect to Domain 3 of ILY is essential for forming a late prepore intermediate that releases CD59, while the role of cholesterol may be limited to insertion of the transmembrane segments. Together these data define a structural timeline for ILY pore formation and suggest a mechanism that is relevant to understanding other pore-forming toxins that also require CD59.
Collapse
Affiliation(s)
- Courtney M. Boyd
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| | - Edward S. Parsons
- Department of Chemistry and Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
| | - Richard A. G. Smith
- MRC Centre for Transplantation, King’s College London, 5th Floor Tower Wing, Guys’ Hospital, London SE1 9RT, UK
| | - John M. Seddon
- Department of Chemistry and Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Oscar Ces
- Department of Chemistry and Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
8
|
Tyler AII, Barriga HMG, Parsons ES, McCarthy NLC, Ces O, Law RV, Seddon JM, Brooks NJ. Electrostatic swelling of bicontinuous cubic lipid phases. Soft Matter 2015; 11:3279-86. [PMID: 25790335 DOI: 10.1039/c5sm00311c] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Lipid bicontinuous cubic phases have attracted enormous interest as bio-compatible scaffolds for use in a wide range of applications including membrane protein crystallisation, drug delivery and biosensing. One of the major bottlenecks that has hindered exploitation of these structures is an inability to create targeted highly swollen bicontinuous cubic structures with large and tunable pore sizes. In contrast, cubic structures found in vivo have periodicities approaching the micron scale. We have been able to engineer and control highly swollen bicontinuous cubic phases of spacegroup Im3m containing only lipids by (a) increasing the bilayer stiffness by adding cholesterol and (b) inducing electrostatic repulsion across the water channels by addition of anionic lipids to monoolein. By controlling the composition of the ternary mixtures we have been able to achieve lattice parameters up to 470 Å, which is 5 times that observed in pure monoolein and nearly twice the size of any lipidic cubic phase reported previously. These lattice parameters significantly exceed the predicted maximum swelling for bicontinuous cubic lipid structures, which suggest that thermal fluctuations should destroy such phases for lattice parameters larger than 300 Å.
Collapse
Affiliation(s)
- Arwen I I Tyler
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Barriga HMG, Parsons ES, McCarthy NLC, Ces O, Seddon JM, Law RV, Brooks NJ. Pressure-temperature phase behavior of mixtures of natural sphingomyelin and ceramide extracts. Langmuir 2015; 31:3678-3686. [PMID: 25742392 DOI: 10.1021/la504935c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ceramides are a group of sphingolipids that act as highly important signaling molecules in a variety of cellular processes including differentiation and apoptosis. The predominant in vivo synthetic pathway for ceramide formation is via sphingomyelinase catalyzed hydrolysis of sphingomyelin. The biochemistry of this essential pathway has been studied in detail; however, there is currently a lack of information on the structural behavior of sphingomyelin- and ceramide-rich model membrane systems, which is essential for developing a bottom-up understanding of ceramide signaling and platform formation. We have studied the lyotropic phase behavior of sphingomyelin-ceramide mixtures in excess water as a function of temperature (30-70 °C) and pressure (1-200 MPa) by small- and wide-angle X-ray scattering. At low ceramide concentrations the mixtures form the ripple gel phase (P(β)') below the gel transition temperature for sphingomyelin, and this observation has been confirmed by atomic force microscopy. Formation of the ripple gel phase can also be induced at higher temperatures via the application of hydrostatic pressure. At high ceramide concentration an inverse hexagonal phase (HII) is formed coexisting with a cubic phase.
Collapse
Affiliation(s)
- Hanna M G Barriga
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Edward S Parsons
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Nicola L C McCarthy
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Oscar Ces
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - John M Seddon
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Robert V Law
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, United Kingdom
| |
Collapse
|
10
|
Barriga HMG, Tyler AII, McCarthy NLC, Parsons ES, Ces O, Law RV, Seddon JM, Brooks NJ. Temperature and pressure tuneable swollen bicontinuous cubic phases approaching nature's length scales. Soft Matter 2015; 11:600-607. [PMID: 25430049 DOI: 10.1039/c4sm02343a] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Bicontinuous cubic structures offer enormous potential in applications ranging from protein crystallisation to drug delivery systems and have been observed in cellular membrane structures. One of the current bottlenecks in understanding and exploiting these structures is that cubic scaffolds produced in vitro are considerably smaller in size than those observed in biological systems, differing by almost an order of magnitude in some cases. We have addressed this technological bottleneck and developed a methodology capable of manufacturing highly swollen bicontinuous cubic membranes with length scales approaching those seen in vivo. Crucially, these cubic systems do not require the presence of proteins. We have generated highly swollen Im3m symmetry bicontinuous cubic phases with lattice parameters of up to 480 Å, composed of ternary mixtures of monoolein, cholesterol and negatively charged lipid (DOPS or DOPG) and we have been able to tune their lattice parameters. The swollen cubic phases are highly sensitive to both temperature and pressure; these structural changes are likely to be controlled by a fine balance between lipid headgroup repulsions and lateral pressure in the hydrocarbon chain region.
Collapse
Affiliation(s)
- H M G Barriga
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
| | | | | | | | | | | | | | | |
Collapse
|