1
|
Gong H, Hu X, Zhang L, Fa K, Liao M, Liu H, Fragneto G, Campana M, Lu JR. How do antimicrobial peptides disrupt the lipopolysaccharide membrane leaflet of Gram-negative bacteria? J Colloid Interface Sci 2023; 637:182-192. [PMID: 36701864 DOI: 10.1016/j.jcis.2023.01.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [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: 11/03/2022] [Revised: 12/24/2022] [Accepted: 01/10/2023] [Indexed: 01/15/2023]
Abstract
HYPOTHESIS It is widely regarded that antimicrobial peptides (AMPs) kill bacteria by physically disrupting microbial membranes and causing cytoplasmic leakage, but it remains unclear how AMPs disrupt the outer membrane (OM) of Gram-negative bacteria (GNB) and then compromise the inner membrane. We hypothesise that different AMPs impose different structural disruptions, with direct implications to their antimicrobial efficacies. EXPERIMENTS The antimicrobial activities of three typical AMPs, including the designed short AMP, G3, and two natural AMPs, melittin and LL37, against E. coli and their haemolytic activities were studied. Lipopolysaccharide (LPS) and anionic di-palmitoyl phosphatidyl glycerol (DPPG) monolayer models were constructed to mimic the outer membrane and inner membrane leaflets of Gram-negative bacteria. The binding and penetration of AMPs to the model lipid monolayers were systematically studied by neutron reflection via multiple H/D contrast variations. FINDING G3 has relatively high antimicrobial activity, low cytotoxicity, and high proteolytic stability, whilst melittin has significant haemolysis and LL37 has weaker antimicrobial activity. G3 could rapidly lyse LPS and DPPG monolayers within 10-20 min. In contrast, melittin was highly active against the LPS membrane, but the dynamic process lasted up to 80 min, with excessive stacking in the OM. LL37 caused rather weak destruction to LPS and DPPG monolayers, leading to massive adsorption on the membrane surface without penetrating the lipid tail region. These findings demonstrate that the rationally designed AMP G3 was well optimised to impose most effective destruction to bacterial membranes, consistent with its highest bactericidal activity. These different interfacial structural features associated with AMP binding shed light on the future development of active and biocompatible AMPs for infection and wound treatments.
Collapse
Affiliation(s)
- Haoning Gong
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Manchester M13 9PL, UK; State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China
| | - Xuzhi Hu
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Manchester M13 9PL, UK
| | - Lin Zhang
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Manchester M13 9PL, UK
| | - Ke Fa
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Manchester M13 9PL, UK
| | - Mingrui Liao
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Manchester M13 9PL, UK
| | - Huayang Liu
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Manchester M13 9PL, UK
| | | | - Mario Campana
- ISIS Pulsed Neutron & Muon Source, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Jian Ren Lu
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, Manchester M13 9PL, UK.
| |
Collapse
|
2
|
Correa Y, Del Giudice R, Waldie S, Thépaut M, Micciula S, Gerelli Y, Moulin M, Delaunay C, Fieschi F, Pichler H, Haertlein M, Forsyth VT, Le Brun A, Moir M, Russell RA, Darwish T, Brinck J, Wodaje T, Jansen M, Martín C, Roosen-Runge F, Cárdenas M. High-Density Lipoprotein function is modulated by the SARS-CoV-2 spike protein in a lipid-type dependent manner. J Colloid Interface Sci 2023; 645:627-638. [PMID: 37167912 PMCID: PMC10147446 DOI: 10.1016/j.jcis.2023.04.137] [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: 02/05/2023] [Revised: 03/22/2023] [Accepted: 04/25/2023] [Indexed: 05/13/2023]
Abstract
There is a close relationship between the SARS-CoV-2 virus and lipoproteins, in particular high-density lipoprotein (HDL). The severity of the coronavirus disease 2019 (COVID-19) is inversely correlated with HDL plasma levels. It is known that the SARS-CoV-2 spike (S) protein binds the HDL particle, probably depleting it of lipids and altering HDL function. Based on neutron reflectometry (NR) and the ability of HDL to efflux cholesterol from macrophages, we confirm these observations and further identify the preference of the S protein for specific lipids and the consequent effects on HDL function on lipid exchange ability. Moreover, the effect of the S protein on HDL function differs depending on the individuals lipid serum profile. Contrasting trends were observed for individuals presenting low triglycerides/high cholesterol serum levels (LTHC) compared to high triglycerides/high cholesterol (HTHC) or low triglycerides/low cholesterol serum levels (LTLC). Collectively, these results suggest that the S protein interacts with the HDL particle and, depending on the lipid profile of the infected individual, it impairs its function during COVID-19 infection, causing an imbalance in lipid metabolism.
Collapse
Affiliation(s)
- Yubexi Correa
- Biofilm - Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, 20506 Malmö, Sweden
| | - Rita Del Giudice
- Biofilm - Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, 20506 Malmö, Sweden
| | - Sarah Waldie
- Biofilm - Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, 20506 Malmö, Sweden; Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Partnership for Structural Biology, Grenoble F-38042, France
| | - Michel Thépaut
- Univ. Grenoble Alpes, CNRS, CEA, IBS, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Samantha Micciula
- Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Large Scale Structures, Institut Laue Langevin (ILL), Grenoble F-38042, France
| | - Yuri Gerelli
- Marche Polytechnic University, Department of Life and Environmental Sciences, Via Brecce Bianche 12, 60131 Ancona, Italy; CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, Rome, Italy
| | - Martine Moulin
- Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Partnership for Structural Biology, Grenoble F-38042, France
| | - Clara Delaunay
- Univ. Grenoble Alpes, CNRS, CEA, IBS, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Franck Fieschi
- Partnership for Structural Biology, Grenoble F-38042, France; Univ. Grenoble Alpes, CNRS, CEA, IBS, 71 avenue des Martyrs, F-38000 Grenoble, France; Institut universitaire de France (IUF), Paris, France
| | - Harald Pichler
- Austrian Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria; Graz University of Technology, Institute of Molecular Biotechnology, NAWI Graz, BioTechMed Graz, Petersgasse 14, 8010 Graz, Austria
| | - Michael Haertlein
- Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Partnership for Structural Biology, Grenoble F-38042, France
| | - V Trevor Forsyth
- Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Partnership for Structural Biology, Grenoble F-38042, France; Faculty of Medicine, Lund University, 22184 Lund, Sweden; LINXS Institute for Advanced Neutron and X-ray Science, Scheelevagen 19, 22370 Lund, Sweden
| | - Anton Le Brun
- National Deuteration Facility, Australian Nuclear Science and Technology Organization (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Michael Moir
- National Deuteration Facility, Australian Nuclear Science and Technology Organization (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Robert A Russell
- National Deuteration Facility, Australian Nuclear Science and Technology Organization (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Tamim Darwish
- National Deuteration Facility, Australian Nuclear Science and Technology Organization (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | | | | | - Martin Jansen
- Institute of Clinical Chemistry and Laboratory Medicine, Medical Centre, University of Freiburg, Freiburg Im Breisgau, Germany
| | - César Martín
- Department of Molecular Biophysics, Biofisika Institute (University of Basque Country and Consejo Superior de Investigaciones Científicas (UPV/EHU, CSIC)), 48940 Leioa, Spain
| | - Felix Roosen-Runge
- Biofilm - Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, 20506 Malmö, Sweden
| | - Marité Cárdenas
- Biofilm - Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, 20506 Malmö, Sweden; Department of Molecular Biophysics, Biofisika Institute (University of Basque Country and Consejo Superior de Investigaciones Científicas (UPV/EHU, CSIC)), 48940 Leioa, Spain; School of Biological Sciences, Nanyang Technological University, Singapore; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
| |
Collapse
|
3
|
Liu H, Fa K, Hu X, Li Z, Zhang L, Ma K, Fragneto G, Li P, Webster JRP, Petkov JT, Thomas RK, Ren Lu J. Structural features of interfacially adsorbed acyl-l-carnitines. J Colloid Interface Sci 2022; 623:368-377. [PMID: 35594595 DOI: 10.1016/j.jcis.2022.05.024] [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: 03/05/2022] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 11/19/2022]
Abstract
HYPOTHESIS Acyl-l-carnitines (CnLCs) are potentially important as biosurfactants in drug delivery and tissue engineering due to their good biocompatibility. However, little is currently known about the basic interfacial behavior underlying their technological applications. Following our previous characterization of their solution aggregation and adsorption at the air/water interface, this work examines how they adsorb at the hydrophilic solid/liquid interface. EXPERIMENTS As the SiO2/water interface has served as the model substrate for many interfacial adsorption studies, so it has been used in this work as the solid substrate to facilitate dynamic adsorption by spectroscopic ellipsometry (SE) and structural determination of the adsorbed layers by neutron reflection (NR) under different conditions at the SiO2/water interface from a group of CnLC (n = 12, 14, and 16). FINDINGS CnLC surfactants are zwitterionic at neutral pH. They reached saturated adsorption above their critical micellar concentrations (CMCs) and formed a sandwich bilayer with a head-tail-head structure at the hydrophilic SiO2/water interface. The total thicknesses of the adsorbed layers at CMC were found to be 33 ± 2, 35 ± 2, and 37 ± 2 Å for C12LC, C14LC, and C16LC, respectively, with their inner and outer head layers remaining similar but the thickness of the interdigitated middle layer increasing with acyl chain length. As the solution becomes acidic, the carboxyl groups become protonated and the l-carnitine heads are net positively charged, resulting in increased repulsion between the head groups. In this situation, the CnLC surfactants are adsorbed as distinct aggregates to reduce repulsive interaction, resulting in reduced surfactant volume fraction and layer thickness. However, a high ionic strength can screen the repulsive interaction and enhance the adsorbed amount, effectively diminishing the impact of pH. This information provides a useful basis for exploring the technological applications of CnLCs involving a solid substrate.
Collapse
Affiliation(s)
- Huayang Liu
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Ke Fa
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Xuzhi Hu
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Zongyi Li
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Lin Zhang
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Kun Ma
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Giovanna Fragneto
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, 38042 Grenoble Cedex 9, France
| | - Peixun Li
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - John R P Webster
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Jordan T Petkov
- Arxada, Hexagon Tower, Delaunays Road, Blackley, Manchester M9 8ZS, UK
| | - Robert K Thomas
- Physical and Theoretical Chemistry, University of Oxford, South Parks, Oxford OX1 3QZ, UK
| | - Jian Ren Lu
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| |
Collapse
|
4
|
Liu H, Fa K, Hu X, Li Z, Ma K, Liao M, Zhang L, Schweins R, Maestro A, Li P, Webster JRP, Petkov J, Thomas RK, Lu JR. How do chain lengths of acyl-l-carnitines affect their surface adsorption and solution aggregation? J Colloid Interface Sci 2021; 609:491-502. [PMID: 34863541 DOI: 10.1016/j.jcis.2021.11.056] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS l-carnitines in our body systems can be readily converted into acyl-l-carnitines which have a prominent place in cellular energy generation by supporting the transport of long-chain fatty acids into mitochondria. As biocompatible surfactants, acyl-l-carnitines have potential to be useful in technical, personal care and healthcare applications. However, the lack of understanding of the effects of their molecular structures on their physical properties has constrained their potential use. EXPERIMENTS This work reports the study of the influence of the acyl chain lengths of acyl-l-carnitines (CnLC) on solubility, surface adsorption and aggregation. Critical micellar concentrations (CMCs) of CnLC were determined by surface tension measurements. Neutron reflection (NR) was used to further examine the structure and composition of the adsorbed CnLC layer. The structural changes of the micellar aggregates under different concentrations of CnLC, pH and ionic strength were determined by dynamic light scattering (DLS) and small angle neutron scattering (SANS). FINDINGS C12LC is fully soluble over a wide temperature and concentration range. There is however a strong decline of solubility with increasing acyl chain length. The adsorption and aggregation behavior of C14LC was therefore studied at 30 °C and C16LC at 45 °C. The solubility boundaries displayed distinct hysteresis with respect to heating and cooling. The CMCs of C12LC, C14LC and C16LC at pH 7 were 1.1 ± 0.1, 0.10 ± 0.02 and 0.010 ± 0.005 mM, respectively, with the limiting values of the area per molecule at the CMC being 45.4 ± 2, 47.5 ± 2 and 48.8 ± 2 Å2 and the thicknesses of the adsorbed CnLC layers at the air/water interface increasing from 21.5 ± 2 to 22.6 ± 2 to 24.2 ± 2 Å, respectively. All three surfactants formed core-shell spherical micelles with comparable dimensional parameters apart from an increase in core radius with acyl chain length. This study outlines the effects of acyl chain length on the physicochemical properties of CnLCs under different environmental conditions, serving as a useful basis for developing their potential applications.
Collapse
Affiliation(s)
- Huayang Liu
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Ke Fa
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Xuzhi Hu
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Zongyi Li
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Kun Ma
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Mingrui Liao
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Lin Zhang
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Ralf Schweins
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, 38042 Grenoble Cedex 9, France
| | - Armando Maestro
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, 38042 Grenoble Cedex 9, France
| | - Peixun Li
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - John R P Webster
- ISIS Neutron Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK
| | - Jordan Petkov
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK; Arxada, Hexagon Tower, Delaunays Road, Blackley, Manchester M9 8ZS, UK.
| | - Robert K Thomas
- Physical and Theoretical Chemistry, University of Oxford, South Parks, Oxford OX1 3QZ, UK
| | - Jian Ren Lu
- Biological Physics Laboratory, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| |
Collapse
|
5
|
Correa Y, Waldie S, Thépaut M, Micciulla S, Moulin M, Fieschi F, Pichler H, Trevor Forsyth V, Haertlein M, Cárdenas M. SARS-CoV-2 spike protein removes lipids from model membranes and interferes with the capacity of high density lipoprotein to exchange lipids. J Colloid Interface Sci 2021; 602:732-739. [PMID: 34157514 PMCID: PMC8195693 DOI: 10.1016/j.jcis.2021.06.056] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 03/27/2021] [Revised: 06/08/2021] [Accepted: 06/09/2021] [Indexed: 01/18/2023]
Abstract
Cholesterol has been shown to affect the extent of coronavirus binding and fusion to cellular membranes. The severity of Covid-19 infection is also known to be correlated with lipid disorders. Furthermore, the levels of both serum cholesterol and high-density lipoprotein (HDL) decrease with Covid-19 severity, with normal levels resuming once the infection has passed. Here we demonstrate that the SARS-CoV-2 spike (S) protein interferes with the function of lipoproteins, and that this is dependent on cholesterol. In particular, the ability of HDL to exchange lipids from model cellular membranes is altered when co-incubated with the spike protein. Additionally, the S protein removes lipids and cholesterol from model membranes. We propose that the S protein affects HDL function by removing lipids from it and remodelling its composition/structure.
Collapse
Affiliation(s)
- Yubexi Correa
- Biofilms - Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, 20506 Malmö, Sweden
| | - Sarah Waldie
- Biofilms - Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, 20506 Malmö, Sweden; Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Partnership for Structural Biology, Grenoble F-38042, France
| | - Michel Thépaut
- Univ. Grenoble Alpes, CNRS, CEA, IBS, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Samantha Micciulla
- Large Scale Structures, Institut Laue Langevin (ILL), Grenoble F-38042, France
| | - Martine Moulin
- Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Partnership for Structural Biology, Grenoble F-38042, France
| | - Franck Fieschi
- Partnership for Structural Biology, Grenoble F-38042, France; Univ. Grenoble Alpes, CNRS, CEA, IBS, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Harald Pichler
- Austrian Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria; Graz University of Technology, Institute of Molecular Biotechnology, NAWI Graz, BioTechMed Graz, Petersgasse 14, 8010 Graz, Austria
| | - V Trevor Forsyth
- Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Partnership for Structural Biology, Grenoble F-38042, France; Faculty of Natural Sciences, Keele University, Staffordshire ST5 5BG, UK.
| | - Michael Haertlein
- Life Sciences Group, Institut Laue Langevin, Grenoble F-38042, France; Partnership for Structural Biology, Grenoble F-38042, France.
| | - Marité Cárdenas
- Biofilms - Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, 20506 Malmö, Sweden.
| |
Collapse
|
6
|
Ciumac D, Gong H, Campbell RA, Campana M, Xu H, Lu JR. Structural elucidation upon binding of antimicrobial peptides into binary mixed lipid monolayers mimicking bacterial membranes. J Colloid Interface Sci 2021; 598:193-205. [PMID: 33901846 DOI: 10.1016/j.jcis.2021.04.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 02/01/2021] [Revised: 04/07/2021] [Accepted: 04/09/2021] [Indexed: 11/28/2022]
Abstract
HYPOTHESIS Antimicrobial peptides (AMPs) kill microorganisms by causing structural damage to bacterial membranes. Different microorganisms often require a different type and concentration of an AMP to achieve full microbial killing. We hypothesise that the difference is caused by different membrane structure and composition. EXPERIMENTS Given the complexities of bacterial membranes, we have used monolayers of the binary DPPG/TMCL mixture to mimic the cytoplasmic membrane of Gram-positive bacteria and the binary DPPG/DPPE mixture to mimic the cytoplasmic membrane of Gram-negative bacteria, where DPPG, TMCL and DPPE stand for 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol), 1',3'-bis[1,2-dimyristoyl-sn-glycero-3-phospho]-sn-glycerol, and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, respectively. A Langmuir trough was specially designed to control the spread lipid monolayers and facilitate neutron reflectivity measurements. FINDINGS Surface pressure-area isotherm analysis revealed that all binary lipid systems mix non-ideally, but mixing is thermodynamically favoured. An increase in the surface pressure encourages demixing, resulting in phase separation and formation of clusters. Neutron reflectivity measurements were undertaken to study the binding of an antimicrobial peptide G(IIKK)4-I-NH2 (G4) to the binary DPPG/TMCL and DPPG/DPPE monolayer mixtures at the molar ratios of 6/4 and 3/7, respectively. The results revealed stronger binding and penetration of G4 to the DPPG/TMCL monolayer, indicating greater affinity of the antimicrobial peptide due to the electrostatic interaction and more extensive penetration into the more loosely packed lipid film. This work helps explain how AMPs attack different bacterial membranes, and the results are discussed in the context of other lipid models and antibacterial studies.
Collapse
Affiliation(s)
- Daniela Ciumac
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Schuster Building, Manchester M13 9PL, UK
| | - Haoning Gong
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Schuster Building, Manchester M13 9PL, UK
| | - Richard A Campbell
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS-20156, 38042 Grenoble, France; Division of Pharmacy and Optometry, University of Manchester, Oxford Road, Stopford Building, Manchester M13 9PT, UK
| | - Mario Campana
- ISIS Neutron Facility, STFC, Chilton, Didcot OX11 0QZ, UK
| | - Hai Xu
- Centre for Bioengineering and Biotechnology, China University of Petroleum, Qingdao, China
| | - Jian R Lu
- Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Schuster Building, Manchester M13 9PL, UK.
| |
Collapse
|
7
|
Wu J, Xu S, Han CC, Yuan G. Controlled drug release: On the evolution of physically entrapped drug inside the electrospun poly(lactic-co-glycolic acid) matrix. J Control Release 2021; 331:472-479. [PMID: 33549717 DOI: 10.1016/j.jconrel.2021.01.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 10/18/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 11/16/2022]
Abstract
The drug loading and releasing properties of poly(lactic-co-glycolic acid) (PLGA) were approached with the application of neutron techniques. The neutron reflection (NR) study on the response of PLGA material to vapor and to bulk water revealed that the hydration of PLGA origins from the molecular compatibility between water and PLGA. Hydration is reversible with regard to the change in humidity and temperature. Capecitabine as drug was embedded in the electrospun PLGA fibers. Small angle neutron scattering (SANS) was able to disclose the domain of entrapped drug inside the fibers and trace its evolution over time when the electrospun membrane was incubated in D2O buffer solution. The evolution of drug domains is discussed in terms of the concentration dependence, the temperature dependence, and the relevance between the drug diffusion inside the polymer matrix and the drug release out to the medium. It was observed that, at 20 °C the drug-related domains are relatively small (~ 100 Å) and relax extremely slow while at 37 °C the drug-related domains are relatively larger (~ 200 Å) and relax faster. These behaviors can be related to the glassy property of structural material. The transportation of drug through the polymer matrix relies on the global relaxation of PLGA chains. The variation of fiber diameter vs. incubation time was followed by ultra-small angle neutron scattering (USANS). The bi-phasic or tri-phasic release kinetics from a series of fibers with different drug loading (2%, 5%, 10%, 20%, 30%, 40%, 50%) were discussed based on the SANS and USANS discovery.
Collapse
Affiliation(s)
- Jiaen Wu
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Shanshan Xu
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA.
| | - Charles C Han
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA
| | - Guangcui Yuan
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA; Department of Physics, Georgetown University, Washington, D. C., 20057, USA.
| |
Collapse
|
8
|
Hu X, Pambou E, Gong H, Liao M, Hollowell P, Liu H, Wang W, Bawn C, Cooper J, Campana M, Ma K, Li P, Webster JRP, Padia F, Bell G, Lu JR. How does substrate hydrophobicity affect the morphological features of reconstituted wax films and their interactions with nonionic surfactant and pesticide? J Colloid Interface Sci 2020; 575:245-253. [PMID: 32361410 DOI: 10.1016/j.jcis.2020.04.043] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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: 03/09/2020] [Revised: 04/08/2020] [Accepted: 04/09/2020] [Indexed: 01/19/2023]
Abstract
HYPOTHESIS Surfactants are widely used in agri-sprays to improve pesticide efficiency, but the mechanism underlying their interactions with the surface wax film on plants remains poorly understood. To facilitate physical characterisations, we have reconstituted wheat cuticular wax films onto an optically flat silicon substrate with and without octadecyltrimethoxysilane modification to control surface hydrophobicity. EXPERIMENTS Imaging techniques including scanning electron microscopy (SEM) unravelled morphological features of the reconstituted wax films similar to those on leaves, showing little impact from the different substrates used. Neutron reflection (NR) established that reconstituted wax films were comprised of an underlying wax film decorated with top surface wax protrusions, a common feature irrespective of substrate hydrophobicity and highly consistent with what was observed from natural wax films. NR measurements, with the help of isotopic H/D substitutions to modify the scattering contributions of the wax and solvent, revealed different wax regimes within the wax films, illustrating the impact of surface hydrophilicity on the nanostructures within the wax films. FINDINGS It was observed from both spectroscopic ellipsometry and NR measurements that wax films formed on the hydrophobic substrate were more robust and durable against attack by nonionic surfactant C12E6 solubilised with pesticide Cyprodinil (CP) than films coated on the bare hydrophilic silica. Thus, the former could be a more feasible model for studying the wax-surfactant-pesticide interactions.
Collapse
Affiliation(s)
- Xuzhi Hu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Elias Pambou
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Haoning Gong
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Mingrui Liao
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Peter Hollowell
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Huayang Liu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Weimiao Wang
- Department of Materials and National Graphene Institute, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Carlo Bawn
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Jos Cooper
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Mario Campana
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Kun Ma
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Peixun Li
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - John R P Webster
- STFC ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Faheem Padia
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Gordon Bell
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Jian R Lu
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| |
Collapse
|
9
|
Waldie S, Sebastiani F, Browning K, Maric S, Lind TK, Yepuri N, Darwish TA, Moulin M, Strohmeier G, Pichler H, Skoda MWA, Maestro A, Haertlein M, Forsyth VT, Bengtsson E, Malmsten M, Cárdenas M. Lipoprotein ability to exchange and remove lipids from model membranes as a function of fatty acid saturation and presence of cholesterol. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158769. [PMID: 32712249 DOI: 10.1016/j.bbalip.2020.158769] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/11/2020] [Accepted: 07/19/2020] [Indexed: 11/23/2022]
Abstract
Lipoproteins play a central role in the development of atherosclerosis. High and low-density lipoproteins (HDL and LDL), known as 'good' and 'bad' cholesterol, respectively, remove and/or deposit lipids into the artery wall. Hence, insight into lipid exchange processes between lipoproteins and cell membranes is of particular importance in understanding the onset and development of cardiovascular disease. In order to elucidate the impact of phospholipid tail saturation and the presence of cholesterol in cell membranes on these processes, neutron reflection was employed in the present investigation to follow lipid exchange with both HDL and LDL against model membranes. Mirroring clinical risk factors for the development of atherosclerosis, lower exchange was observed in the presence of cholesterol, as well as for an unsaturated phospholipid, compared to faster exchange when using a fully saturated phospholipid. These results highlight the importance of membrane composition on the interaction with lipoproteins, chiefly the saturation level of the lipids and presence of cholesterol, and provide novel insight into factors of importance for build-up and reversibility of atherosclerotic plaque. In addition, the correlation between the results and well-established clinical risk factors suggests that the approach taken can be employed also for understanding a broader set of risk factors including, e.g., effects of triglycerides and oxidative stress, as well as local effects of drugs on atherosclerotic plaque formation.
Collapse
|
10
|
Browning KL, Lind TK, Maric S, Barker RD, Cárdenas M, Malmsten M. Effect of bilayer charge on lipoprotein lipid exchange. Colloids Surf B Biointerfaces 2018; 168:117-125. [PMID: 29422308 DOI: 10.1016/j.colsurfb.2018.01.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [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: 09/20/2017] [Revised: 12/22/2017] [Accepted: 01/20/2018] [Indexed: 12/17/2022]
Abstract
Lipoproteins play a key role in the onset and development of atherosclerosis, the formation of lipid plaques at blood vessel walls. The plaque formation, as well as subsequent calcification, involves not only endothelial cells but also connective tissue, and is closely related to a wide range of cardiovascular syndromes, that together constitute the number one cause of death in the Western World. High (HDL) and low (LDL) density lipoproteins are of particular interest in relation to atherosclerosis, due to their protective and harmful effects, respectively. In an effort to elucidate the molecular mechanisms underlying this, and to identify factors determining lipid deposition and exchange at lipid membranes, we here employ neutron reflection (NR) and quartz crystal microbalance with dissipation (QCM-D) to study the effect of membrane charge on lipoprotein deposition and lipid exchange. Dimyristoylphosphatidylcholine (DMPC) bilayers containing varying amounts of negatively charged dimyristoylphosphatidylserine (DMPS) were used to vary membrane charge. It was found that the amount of hydrogenous material deposited from either HDL or LDL to the bilayer depends only weakly on membrane charge density. In contrast, increasing membrane charge resulted in an increase in the amount of lipids removed from the supported lipid bilayer, an effect particularly pronounced for LDL. The latter effects are in line with previously reported observations on atherosclerotic plaque prone regions of long-term hyperlipidaemia and type 2 diabetic patients, and may also provide some molecular clues into the relation between oxidative stress and atherosclerosis.
Collapse
Affiliation(s)
- Kathryn Louise Browning
- Department of Pharmacy, Uppsala University, Uppsala, Sweden; Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark.
| | - Tania Kjellerup Lind
- Department of Biomedical Sciences and Biofilms - Research Centre for Biointerfaces, Malmö University, Malmö, Sweden
| | - Selma Maric
- Department of Biomedical Sciences and Biofilms - Research Centre for Biointerfaces, Malmö University, Malmö, Sweden
| | | | - Marité Cárdenas
- Department of Biomedical Sciences and Biofilms - Research Centre for Biointerfaces, Malmö University, Malmö, Sweden.
| | - Martin Malmsten
- Department of Pharmacy, Uppsala University, Uppsala, Sweden; Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
11
|
Pan F, Lu Z, Tucker I, Hosking S, Petkov J, Lu JR. Surface active complexes formed between keratin polypeptides and ionic surfactants. J Colloid Interface Sci 2016; 484:125-134. [PMID: 27599381 DOI: 10.1016/j.jcis.2016.08.082] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [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: 06/21/2016] [Revised: 08/30/2016] [Accepted: 08/31/2016] [Indexed: 12/26/2022]
Abstract
Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C12TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes.
Collapse
Affiliation(s)
- Fang Pan
- Biological Physics Group, Schuster Building, Oxford Road, The University of Manchester, Manchester M13 9PL, UK
| | - Zhiming Lu
- Biological Physics Group, Schuster Building, Oxford Road, The University of Manchester, Manchester M13 9PL, UK
| | - Ian Tucker
- Unilever R&D Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, UK
| | - Sarah Hosking
- Unilever R&D Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, UK
| | - Jordan Petkov
- Unilever R&D Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, UK; Menara KLK 1, Jalan Pju 7/6, Mutiara Damansara, 47810, Petaling Jaya, Selangor 47800, Malaysia
| | - Jian R Lu
- Biological Physics Group, Schuster Building, Oxford Road, The University of Manchester, Manchester M13 9PL, UK.
| |
Collapse
|
12
|
Hellsing MS, Josefsson S, Hughes AV, Ahrens L. Sorption of perfluoroalkyl substances to two types of minerals. Chemosphere 2016; 159:385-391. [PMID: 27323291 DOI: 10.1016/j.chemosphere.2016.06.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 05/26/2016] [Accepted: 06/03/2016] [Indexed: 06/06/2023]
Abstract
The sorption of perfluoroalkyl substances (PFASs) was investigated for two model soil mineral surfaces, alumina (Al2O3) and silica (SiO2), on molecular level using neutron scattering. The PFASs were selected (i.e. perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorooctane sulfonic acid (PFOS)) to examine the role of hydrophobic chain length and hydrophilic functional group on their sorption behaviour. All four PFASs were found to sorb to alumina surface (positively charged) forming a hydrated layer consisting of 50% PFASs. The PFAS solubility limit, which decrease with chain length, was found to strongly influence the sorption behaviour. The sorbed PFAS layer could easily be removed by gentle rinsing with water, indicating release upon rainfall in the environment. No sorption was observed for PFOA and PFOS at silica surface (negatively charged), showing electrostatic interaction being the driving force in the sorption process.
Collapse
Affiliation(s)
- Maja S Hellsing
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20, Uppsala, Sweden.
| | - Sarah Josefsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, SE-750 07, Uppsala, Sweden
| | - Arwel V Hughes
- Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX, United Kingdom
| | - Lutz Ahrens
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, SE-750 07, Uppsala, Sweden
| |
Collapse
|
13
|
Lind TK, Darré L, Domene C, Urbanczyk-Lipkowska Z, Cárdenas M, Wacklin HP. Antimicrobial peptide dendrimer interacts with phosphocholine membranes in a fluidity dependent manner: A neutron reflection study combined with molecular dynamics simulations. Biochim Biophys Acta 2015; 1848:2075-84. [PMID: 26025586 DOI: 10.1016/j.bbamem.2015.05.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/20/2015] [Accepted: 05/20/2015] [Indexed: 10/23/2022]
Abstract
The interaction mechanism of a novel amphiphilic antimicrobial peptide dendrimer, BALY, with model lipid bilayers was explored through a combination of neutron reflection and molecular dynamics simulations. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dipalmitoyl-sn-glycero-3-phos-phocholine (DPPC) lipid bilayers were examined at room temperature to extract information on the interaction of BALY with fluid and gel phases, respectively. Furthermore, a 1:4 mixture of POPC and DPPC was used as a model of a phase-separated membrane. Upon interaction with fluid membranes, BALY inserted in the distal leaflet and caused thinning and disordering of the headgroups. Membrane thinning and expansion of the lipid cross-sectional area were observed for gel phase membranes, also with limited insertion to the distal leaflet. However, dendrimer insertion through the entire lipid tail region was observed upon crossing the lipid phase transition temperature of DPPC and in phase separated membranes. The results show clear differences in the interaction mechanism of the dendrimer depending on the lipid membrane fluidity, and suggest a role for lipid phase separation in promoting its antimicrobial activity.
Collapse
Affiliation(s)
- T K Lind
- Institute of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK 2100 Copenhagen, Denmark; European Spallation Source ESS AB, P.O. Box 176, 22100 Lund, Sweden
| | - L Darré
- Department of Chemistry, King's College London, London SE1 9NH, UK
| | - C Domene
- Department of Chemistry, King's College London, London SE1 9NH, UK; Chemistry Research Laboratory, Mansfield Road, University of Oxford, Oxford OX1 3TA, UK
| | | | - M Cárdenas
- Institute of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK 2100 Copenhagen, Denmark; Malmoe University, Health & Society, 20506 Malmoe, Sweden.
| | - H P Wacklin
- Institute of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK 2100 Copenhagen, Denmark; European Spallation Source ESS AB, P.O. Box 176, 22100 Lund, Sweden.
| |
Collapse
|
14
|
Kwaambwa HM, Hellsing MS, Rennie AR, Barker R. Interaction of Moringa oleifera seed protein with a mineral surface and the influence of surfactants. J Colloid Interface Sci 2015; 448:339-46. [PMID: 25746187 DOI: 10.1016/j.jcis.2015.02.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [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: 12/20/2014] [Revised: 02/11/2015] [Accepted: 02/11/2015] [Indexed: 10/24/2022]
Abstract
The paper describes the adsorption of purified protein from seeds of Moringa oleifera to a sapphire interface and the effects of addition of the anionic surfactant sodium dodecylsulfate (SDS) and the cationic surfactant hexadecyltrimethylammonium bromide (CTAB). Neutron reflection was used to determine the structure and composition of interfacial layers adsorbed at the solid/solution interface. The maximum surface excess of protein was found to be about 5.3 mg m(-2). The protein does not desorb from the solid/liquid interface when rinsed with water. Addition of SDS increases the reflectivity indicating co-adsorption. It was observed that CTAB is able to remove the protein from the interface. The distinct differences to the behavior observed previously for the protein at the silica/water interface are identified. The adsorption of the protein to alumina in addition to other surfaces has shown why it is an effective flocculating agent for the range of impurities found in water supplies. The ability to tailor different surface layers in combination with various surfactants also offers the potential for adsorbed protein to be used in separation technologies.
Collapse
Affiliation(s)
- Habauka M Kwaambwa
- Polytechnic of Namibia, School of Health and Applied Sciences, Private Bag 13388, 13 Storch Street, Windhoek, Namibia.
| | - Maja S Hellsing
- Materials Physics, Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, Box 516, 751 20, Uppsala, Sweden
| | - Adrian R Rennie
- Materials Physics, Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, Box 516, 751 20, Uppsala, Sweden.
| | - Robert Barker
- Institut Laue Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| |
Collapse
|
15
|
Nanda H, Heinrich F, Lösche M. Membrane association of the PTEN tumor suppressor: neutron scattering and MD simulations reveal the structure of protein-membrane complexes. Methods 2014; 77-78:136-46. [PMID: 25461777 DOI: 10.1016/j.ymeth.2014.10.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [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] [Received: 08/31/2014] [Revised: 10/10/2014] [Accepted: 10/14/2014] [Indexed: 12/31/2022] Open
Abstract
Neutron reflection (NR) from planar interfaces is an emerging technology that provides unique and otherwise inaccessible structural information on disordered molecular systems such as membrane proteins associated with fluid bilayers, thus addressing one of the remaining challenges of structural biology. Although intrinsically a low-resolution technique, using structural information from crystallography or NMR allows the construction of NR models that describe the architecture of protein-membrane complexes at high resolution. In addition, a combination of these methods with molecular dynamics (MD) simulations has the potential to reveal the dynamics of protein interactions with the bilayer in atomistic detail. We review recent advances in this area by discussing the application of these techniques to the complex formed by the PTEN phosphatase with the plasma membrane. These studies provide insights in the cellular regulation of PTEN, its interaction with PI(4,5)P2 in the inner plasma membrane and the pathway by which its substrate, PI(3,4,5)P3, accesses the PTEN catalytic site.
Collapse
Affiliation(s)
- Hirsh Nanda
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| |
Collapse
|