1
|
Waller C, Marzinek JK, McBurnie E, Bond PJ, Williamson PTF, Khalid S. Impact on S. aureus and E. coli Membranes of Treatment with Chlorhexidine and Alcohol Solutions: Insights from Molecular Simulations and Nuclear Magnetic Resonance. J Mol Biol 2023; 435:167953. [PMID: 37330283 DOI: 10.1016/j.jmb.2023.167953] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 12/16/2022] [Accepted: 01/04/2023] [Indexed: 06/19/2023]
Abstract
Membranes form the first line of defence of bacteria against potentially harmful molecules in the surrounding environment. Understanding the protective properties of these membranes represents an important step towards development of targeted anti-bacterial agents such as sanitizers. Use of propanol, isopropanol and chlorhexidine can significantly decrease the threat imposed by bacteria in the face of growing anti-bacterial resistance via mechanisms that include membrane disruption. Here we have employed molecular dynamics simulations and nuclear magnetic resonance to explore the impact of chlorhexidine and alcohol on the S. aureus cell membrane, as well as the E. coli inner and outer membranes. We identify how sanitizer components partition into these bacterial membranes, and show that chlorhexidine is instrumental in this process.
Collapse
Affiliation(s)
- Callum Waller
- School of Chemistry, University of Southampton, SO17 1BJ, UK; Bioinformatics Institute, 30 Biopolis Street, Singapore 138671, Singapore
| | - Jan K Marzinek
- Bioinformatics Institute, 30 Biopolis Street, Singapore 138671, Singapore
| | - Eilish McBurnie
- School of Chemistry, University of Southampton, SO17 1BJ, UK; Bioinformatics Institute, 30 Biopolis Street, Singapore 138671, Singapore
| | - Peter J Bond
- Bioinformatics Institute, 30 Biopolis Street, Singapore 138671, Singapore; National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | | | - Syma Khalid
- School of Chemistry, University of Southampton, SO17 1BJ, UK; Department of Biochemistry, University of Oxford, OX1 3QU, UK.
| |
Collapse
|
2
|
Molugu TR, Thurmond RL, Alam TM, Trouard TP, Brown MF. Phospholipid headgroups govern area per lipid and emergent elastic properties of bilayers. Biophys J 2022; 121:4205-4220. [PMID: 36088534 PMCID: PMC9674990 DOI: 10.1016/j.bpj.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 08/10/2022] [Accepted: 09/06/2022] [Indexed: 11/24/2022] Open
Abstract
Phospholipid bilayers are liquid-crystalline materials whose intermolecular interactions at mesoscopic length scales have key roles in the emergence of membrane physical properties. Here we investigated the combined effects of phospholipid polar headgroups and acyl chains on biophysical functions of membranes with solid-state 2H NMR spectroscopy. We compared the structural and dynamic properties of phosphatidylethanolamine and phosphatidylcholine with perdeuterated acyl chains in the solid-ordered (so) and liquid-disordered (ld) phases. Our analysis of spectral lineshapes of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE-d62) and 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine (DPPC-d62) in the so (gel) phase indicated an all-trans rotating chain structure for both lipids. Greater segmental order parameters (SCD) were observed in the ld (liquid-crystalline) phase for DPPE-d62 than for DPPC-d62 membranes, while their mixtures had intermediate values irrespective of the deuterated lipid type. Our results suggest the SCD profiles of the acyl chains are governed by methylation of the headgroups and are averaged over the entire system. Variations in the acyl chain molecular dynamics were further investigated by spin-lattice (R1Z) and quadrupolar-order relaxation (R1Q) measurements. The two acyl-perdeuterated lipids showed distinct differences in relaxation behavior as a function of the order parameter. The R1Z rates had a square-law dependence on SCD, implying collective mesoscopic dynamics, with a higher bending rigidity for DPPE-d62 than for DPPC-d62 lipids. Remodeling of lipid average and dynamic properties by methylation of the headgroups thus provides a mechanism to control the actions of peptides and proteins in biomembranes.
Collapse
Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | | | - Todd M Alam
- Department of Organic Materials Science, Sandia National Laboratories, Albuquerque, New Mexico
| | - Theodore P Trouard
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
| |
Collapse
|
3
|
Doole FT, Kumarage T, Ashkar R, Brown MF. Cholesterol Stiffening of Lipid Membranes. J Membr Biol 2022; 255:385-405. [PMID: 36219221 PMCID: PMC9552730 DOI: 10.1007/s00232-022-00263-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/05/2022] [Indexed: 11/30/2022]
Abstract
Biomembrane order, dynamics, and other essential physicochemical parameters are controlled by cholesterol, a major component of mammalian cell membranes. Although cholesterol is well known to exhibit a condensing effect on fluid lipid membranes, the extent of stiffening that occurs with different degrees of lipid acyl chain unsaturation remains an enigma. In this review, we show that cholesterol locally increases the bending rigidity of both unsaturated and saturated lipid membranes, suggesting there may be a length-scale dependence of the bending modulus. We review our published data that address the origin of the mechanical effects of cholesterol on unsaturated and polyunsaturated lipid membranes and their role in biomembrane functions. Through a combination of solid-state deuterium NMR spectroscopy and neutron spin-echo spectroscopy, we show that changes in molecular packing cause the universal effects of cholesterol on the membrane bending rigidity. Our findings have broad implications for the role of cholesterol in lipid–protein interactions as well as raft-like mixtures, drug delivery applications, and the effects of antimicrobial peptides on lipid membranes.
Collapse
Affiliation(s)
- Fathima T Doole
- Deaprtment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85712, USA
| | - Teshani Kumarage
- Department of Physics, Virginia Tech, Blacksburg, VA, 24061, USA.,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA, 24061, USA. .,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Michael F Brown
- Deaprtment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85712, USA. .,Department of Physics, University of Arizona, Tucson, AZ, 85712, USA.
| |
Collapse
|
4
|
Gravel AE, Arnold AA, Fillion M, Auger M, Warschawski DE, Marcotte I. Magnetically-orientable Tween-based model membranes for NMR studies of proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183379. [DOI: 10.1016/j.bbamem.2020.183379] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 05/15/2020] [Accepted: 05/18/2020] [Indexed: 11/16/2022]
|
5
|
Molugu TR, Lee S, Brown MF. Concepts and Methods of Solid-State NMR Spectroscopy Applied to Biomembranes. Chem Rev 2017; 117:12087-12132. [PMID: 28906107 DOI: 10.1021/acs.chemrev.6b00619] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Concepts of solid-state NMR spectroscopy and applications to fluid membranes are reviewed in this paper. Membrane lipids with 2H-labeled acyl chains or polar head groups are studied using 2H NMR to yield knowledge of their atomistic structures in relation to equilibrium properties. This review demonstrates the principles and applications of solid-state NMR by unifying dipolar and quadrupolar interactions and highlights the unique features offered by solid-state 2H NMR with experimental illustrations. For randomly oriented multilamellar lipids or aligned membranes, solid-state 2H NMR enables direct measurement of residual quadrupolar couplings (RQCs) due to individual C-2H-labeled segments. The distribution of RQC values gives nearly complete profiles of the segmental order parameters SCD(i) as a function of acyl segment position (i). Alternatively, one can measure residual dipolar couplings (RDCs) for natural abundance lipid samples to obtain segmental SCH order parameters. A theoretical mean-torque model provides acyl-packing profiles representing the cumulative chain extension along the normal to the aqueous interface. Equilibrium structural properties of fluid bilayers and various thermodynamic quantities can then be calculated, which describe the interactions with cholesterol, detergents, peptides, and integral membrane proteins and formation of lipid rafts. One can also obtain direct information for membrane-bound peptides or proteins by measuring RDCs using magic-angle spinning (MAS) in combination with dipolar recoupling methods. Solid-state NMR methods have been extensively applied to characterize model membranes and membrane-bound peptides and proteins, giving unique information on their conformations, orientations, and interactions in the natural liquid-crystalline state.
Collapse
Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
| | - Soohyun Lee
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
| | - Michael F Brown
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
| |
Collapse
|
6
|
Ashworth Briggs EL, Gomes RGB, Elhussein M, Collier W, Findlow IS, Khalid S, McCormick CJ, Williamson PTF. Interaction between the NS4B amphipathic helix, AH2, and charged lipid headgroups alters membrane morphology and AH2 oligomeric state--Implications for the Hepatitis C virus life cycle. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1671-7. [PMID: 25944559 PMCID: PMC4768108 DOI: 10.1016/j.bbamem.2015.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 02/27/2015] [Accepted: 04/25/2015] [Indexed: 01/27/2023]
Abstract
The non-structural protein 4B (NS4B) from Hepatitis C virus (HCV) plays a pivotal role in the remodelling of the host cell's membranes, required for the formation of the viral replication complex where genome synthesis occurs. NS4B is an integral membrane protein that possesses a number of domains vital for viral replication. Structural and biophysical studies have revealed that one of these, the second amphipathic N-terminal helix (AH2), plays a key role in these remodelling events. However, there is still limited understanding of the mechanism through which AH2 promotes these changes. Here we report on solid-state NMR and molecular dynamics studies that demonstrate that AH2 promotes the clustering of negatively charged lipids within the bilayer, a process that reduces the strain within the bilayer facilitating the remodelling of the lipid bilayer. Furthermore, the presence of negatively charged lipids within the bilayer appears to promote the disassociation of AH2 oligomers, highlighting a potential role for lipid recruitment in regulating NS protein interactions. Changes in membrane morphology studied by 2H and 31P Solid-state NMR. Bilayer charge influences the oligomeric state of the amphipathic helix AH2 from NS4B. Interaction of AH2 with charged lipid membranes reduces strain within bilayer. AH2 from NS4B is involved in membrane remodelling and membranous web formation. Lipid bilayer/NS4B interactions may regulate Hepatitis C virus lifecycle.
Collapse
Affiliation(s)
- Esther L Ashworth Briggs
- Centre for Biological Sciences/Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Rafael G B Gomes
- Centre for Biological Sciences/Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK; School of Medicine, University of Southampton, Southampton SO16 6YD, UK
| | - Malaz Elhussein
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
| | - William Collier
- Centre for Biological Sciences/Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - I Stuart Findlow
- Centre for Biological Sciences/Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
| | - Chris J McCormick
- School of Medicine, University of Southampton, Southampton SO16 6YD, UK.
| | - Philip T F Williamson
- Centre for Biological Sciences/Institute for Life Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK.
| |
Collapse
|
7
|
Abstract
In this chapter we describe the use of solid state nuclear magnetic spectroscopy to study the structure of lyotropic phases and lipid model membranes and show its ability to probe, site specifically, at a sub-Ångstrom resolution. Here, we demonstrate the immense versatility of the technique and its ability to provide information on the different liquid crystalline phases present. A multinuclear for example (31)P, (1)H, and (13)C approach is able to elucidate both the structure and dynamics over a wide variety of timescales. This coupled with a non-perturbing label (2)H is able to provide information such as the order parameters for a wide variety of different liquid phases.
Collapse
Affiliation(s)
- Arwen I I Tyler
- Department of Chemistry, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK,
| | | | | | | |
Collapse
|
8
|
Costello AL, Alam TM. Investigating the impact of cholesterol on magnetically aligned sphingomyelin/cholesterol multilamellar vesicles using static (31)P NMR. Chem Phys Lipids 2010; 163:506-13. [PMID: 20385112 DOI: 10.1016/j.chemphyslip.2010.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 02/18/2010] [Accepted: 04/05/2010] [Indexed: 10/19/2022]
Abstract
The effect of cholesterol (5-40mol%) on the magnetic induced orientation of sphingomyelin/cholesterol multilamellar vesicles (MLVs) was examined using static solid state (31)P NMR spectroscopy. The orientation was modeled assuming an ellipsoidal deformation of the vesicles and was monitored as a function of cholesterol concentration and temperature. In addition, the static (31)P chemical shift anisotropy (CSA) was used to assess the motional and dynamical changes occurring in the bilayer are reported. An exploration of the factors determining the magnetic orientation in sphingomyelin/cholesterol bilayers from the gel (s(o)) to liquid crystalline (or liquid-ordered, l(o)) phases is presented and discussed.
Collapse
Affiliation(s)
- Alison L Costello
- Department of Electronic and Nanostructured Materials, Sandia National Laboratories, Albuquerque, NM 87185-0886, United States
| | | |
Collapse
|
9
|
Ausili A, Torrecillas A, Aranda F, de Godos A, Sánchez-Bautista S, Corbalán-García S, Gómez-Fernández JC. Redox State of Coenzyme Q10 Determines Its Membrane Localization. J Phys Chem B 2008; 112:12696-702. [DOI: 10.1021/jp802215s] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alessio Ausili
- Departamento de Bioquímica y Biología Molecular (A), Facultad de Veterinaria, Universidad de Murcia, Apartado de Correos 4021, E-30080-Murcia, Spain
| | - Alejandro Torrecillas
- Departamento de Bioquímica y Biología Molecular (A), Facultad de Veterinaria, Universidad de Murcia, Apartado de Correos 4021, E-30080-Murcia, Spain
| | - Francisco Aranda
- Departamento de Bioquímica y Biología Molecular (A), Facultad de Veterinaria, Universidad de Murcia, Apartado de Correos 4021, E-30080-Murcia, Spain
| | - Ana de Godos
- Departamento de Bioquímica y Biología Molecular (A), Facultad de Veterinaria, Universidad de Murcia, Apartado de Correos 4021, E-30080-Murcia, Spain
| | - Sonia Sánchez-Bautista
- Departamento de Bioquímica y Biología Molecular (A), Facultad de Veterinaria, Universidad de Murcia, Apartado de Correos 4021, E-30080-Murcia, Spain
| | - Senena Corbalán-García
- Departamento de Bioquímica y Biología Molecular (A), Facultad de Veterinaria, Universidad de Murcia, Apartado de Correos 4021, E-30080-Murcia, Spain
| | - Juan C. Gómez-Fernández
- Departamento de Bioquímica y Biología Molecular (A), Facultad de Veterinaria, Universidad de Murcia, Apartado de Correos 4021, E-30080-Murcia, Spain
| |
Collapse
|
10
|
Dubinnyi MA, Lesovoy DM, Dubovskii PV, Chupin VV, Arseniev AS. Modeling of 31P-NMR spectra of magnetically oriented phospholipid liposomes: A new analytical solution. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2006; 29:305-11. [PMID: 16298110 DOI: 10.1016/j.ssnmr.2005.10.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 09/26/2005] [Indexed: 05/05/2023]
Abstract
31P-NMR spectroscopy is widely used for studies of phospholipid liposomes, a commonly used model of a biological membrane. For the correct analysis of 31P-NMR spectra of the liposomes it is necessary to take into account that they are deformed by the magnetic field of the spectrometer. The liposomes become ellipsoidal and this affects the lineshape of the spectrum. In the present communication we suggest a new analytical formula for modeling of 31P-NMR spectra of the prolate phospholipid liposomes. The formula assumes a Lorentzian broadening function and exactly ellipsoidal shape of the liposomes. Based on the formula a program called P-FIT is designed for the practical analysis of the experimental multicomponent spectra of the prolate liposomes. The versatility of the program developed in a Mathematica environment is demonstrated by simulations of a number of 31P-NMR spectra with different complexity.
Collapse
Affiliation(s)
- Maxim A Dubinnyi
- Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya str., V-437, Moscow 117997, Russia Federation
| | | | | | | | | |
Collapse
|
11
|
Chupin V, Boots JW, Killian JA, Demel RA, de Kruijff B. Lipid organization and dynamics of the monostearoylglycerol-water system. A 2H NMR study. Chem Phys Lipids 2001; 109:15-28. [PMID: 11163341 DOI: 10.1016/s0009-3084(00)00206-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Deuterium labeled monostearoylglycerols with fully ([2H(35)]-MSG) and selectively ([11-(2)H(2)]-MSG) deuterated chains have been synthesized and used as a probe for 2H NMR. At low temperature monoglyceride-water systems form the coagel or crystalline phase, which transforms with increasing temperature subsequently into the gel, liquid crystalline and cubic phase. The 2H NMR spectra exhibit characteristic features representative of these phases. The gel phase is metastable and gradually transforms into the coagel at temperatures below 40 degrees C. The undercooled cubic phase transforms into the liquid crystalline phase during days. In the liquid crystalline phase, the chain order profile indicates an increase of the chain flexibility towards the methyl group. In the liquid crystalline phase, bilayers spontaneously align in a magnetic field with their normal perpendicular to the field. The results demonstrate that 2H NMR can serve as a convenient tool to study both structure and dynamics of different monoglyceride-water phases.
Collapse
Affiliation(s)
- V Chupin
- Department Biochemistry of Membranes, Centre for Biomembranes and Lipid Enzymology, Utrecht University, Padualaan 8, 3584 Utrecht CH, The Netherlands.
| | | | | | | | | |
Collapse
|
12
|
Otten D, Brown MF, Beyer K. Softening of Membrane Bilayers by Detergents Elucidated by Deuterium NMR Spectroscopy. J Phys Chem B 2000. [DOI: 10.1021/jp001505e] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dörte Otten
- Lehrstuhl für Stoffwechselbiochemie der Universität München, Germany, and Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Michael F. Brown
- Lehrstuhl für Stoffwechselbiochemie der Universität München, Germany, and Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Klaus Beyer
- Lehrstuhl für Stoffwechselbiochemie der Universität München, Germany, and Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| |
Collapse
|
13
|
Picard F, Paquet MJ, Levesque J, Bélanger A, Auger M. 31P NMR first spectral moment study of the partial magnetic orientation of phospholipid membranes. Biophys J 1999; 77:888-902. [PMID: 10423434 PMCID: PMC1300380 DOI: 10.1016/s0006-3495(99)76940-7] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Structural data can be obtained on proteins inserted in magnetically oriented phospholipid membranes such as bicelles, which are most often made of a mixture of long and short chain phosphatidylcholine. Possible shapes for these magnetically oriented membranes have been postulated in the literature, such as discoidal structures with a thickness of one bilayer and with the short acyl chain phosphatidylcholine on the edges. In the present paper, a geometrical study of these oriented structures is done to determine the validity of this model. The method used is based on the determination of the first spectral moment of solid-state (31)P nuclear magnetic resonance spectra. From this first moment, an order parameter is defined that allows a quantitative analysis of partially oriented spectra. The validity of this method is demonstrated in the present study for oriented samples made of DMPC, DMPC:DHPC, DMPC:DHPC:gramicidin A and adriamycin:cardiolipin.
Collapse
Affiliation(s)
- F Picard
- Département de Chimie, Centre de Recherche en Sciences et Ingénierie des Macromolécules, Université Laval, Québec, Québec G1K 7P4, Canada
| | | | | | | | | |
Collapse
|
14
|
Prosser RS, Hwang JS, Vold RR. Magnetically aligned phospholipid bilayers with positive ordering: a new model membrane system. Biophys J 1998; 74:2405-18. [PMID: 9591667 PMCID: PMC1299583 DOI: 10.1016/s0006-3495(98)77949-4] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A stable smectic phospholipid bilayer phase aligned with the director parallel to the magnetic field can be generated by the addition of certain trivalent paramagnetic lanthanide ions to a bicellar solution of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC) in water. Suitable lanthanide ions are those with positive anisotropy of their magnetic susceptibility, namely Eu3+, Er3+, Tm3+, and Yb3+. For samples doped with Tm3+, this phase extends over a wide range of Tm3+ concentrations (6-40 mM) and temperatures (35-90 degrees C) and appears to undergo a transition from a fluid nematic discotic to a fluid, but highly ordered, smectic phase at a temperature that depends on the thulium concentration. As a membrane mimetic, these new, positively ordered phospholipid phases have high potential for structural studies using a variety of techniques such as magnetic resonance (EMR and NMR), small-angle x-ray and neutron diffraction, as well as optical and infrared spectroscopy.
Collapse
Affiliation(s)
- R S Prosser
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla 92093-0359, USA
| | | | | |
Collapse
|
15
|
|
16
|
Firouzi A, Schaefer DJ, Tolbert SH, Stucky GD, Chmelka BF. Magnetic-Field-Induced Orientational Ordering of Alkaline Lyotropic Silicate−Surfactant Liquid Crystals. J Am Chem Soc 1997. [DOI: 10.1021/ja971267+] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
17
|
Chapter 3 NMR Studies of Membrane Lipid Properties. CURRENT TOPICS IN MEMBRANES 1997. [DOI: 10.1016/s0070-2161(08)60207-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
|
18
|
Abstract
The damaging effects of synchrotron-derived x rays on aqueous phospholipid dispersions have been evaluated. The effect of degree of lipid hydration, phospholipid chemical structure, mesophase identity, aqueous medium composition, and incident flux on the severity and progress of damage was quantified using time-resolved x-ray diffraction and chromatographic analysis of damage products. Electron spin resonance measurements of spin-trapped intermediates generated during irradiation suggest a free radical-mediated process. Surprisingly, radiation damage effects revealed by x-ray diffraction were imperceptible when the lamellar phases were prepared under water-stressed conditions, despite the fact that x-ray-induced chemical breakdown of the lipid occurred regardless of hydration level. Of the fully hydrated lipid systems studied, saturated diacyl-phosphatidylcholines were most sensitive to radiation damage compared to the ester- and ether-linked phosphatidylethanolamines and the ether-linked phosphatidylcholines. The inclusion of buffers or inorganic salts in the dispersing medium had only a minor effect in reducing damage development. A small inverse dose-rate effect was found when the x-ray beam intensity was changed 15-fold. These results contribute to our understanding of the mechanism of radiation damage, to our appreciation of the importance of monitoring both structure and composition when evaluating biomaterials radiation sensitivity, and to the development of strategies for eliminating or reducing the severity of damage due to an increasingly important source of x rays, synchrotron radiation. Because damage is shown to be free radical mediated, these results have an important bearing on age-related accumulation of free radicals in cells and how these might compromise membrane integrity, culminating in cell death.
Collapse
Affiliation(s)
- A Cheng
- Department of Chemistry, Ohio State University, Columbus 43210, USA
| | | |
Collapse
|
19
|
Sheffield MJ, Baker BL, Li D, Owen NL, Baker ML, Bell JD. Enhancement of Agkistrodon piscivorus piscivorus venom phospholipase A2 activity toward phosphatidylcholine vesicles by lysolecithin and palmitic acid: studies with fluorescent probes of membrane structure. Biochemistry 1995; 34:7796-806. [PMID: 7794890 DOI: 10.1021/bi00024a003] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The activity of phospholipase A2 from snake venom to hydrolyze bilayers of phosphatidylcholines is greatly enhanced by the presence of the hydrolysis products, lysolecithin and fatty acid, in the bilayer. The fluorescence of several probes of membrane structure was used to monitor changes in bilayer physical properties during vesicle hydrolysis. These changes were compared to emission spectra and fluorescence polarization results occurring upon direct addition of lysolecithin and/or fatty acid to the bilayer. The excimer to monomer ratio of 1,3-bis(1-pyrene)propane was insensitive to vesicle hydrolysis, suggesting that changes in the order of the phospholipid chains were not relevant to the effect of the hydrolysis products on phospholipase activity. The fluorescence of 6-propionyl-2-(dimethylamino)-naphthalene (Prodan) suggested that the polarity of the bilayer in the region of the phospholipid head groups increases as the hydrolysis products accumulate in the bilayer. The fluorescence of 6-dodecanoyl-2-(dimethylamino)naphthalene (Laurdan) confirmed that such effects were restricted to the bilayer surface. Furthermore, the lysolecithin appeared to be the product most responsible for these changes. These results suggested that lysolecithin increases the activity of phospholipase A2 during vesicle hydrolysis by disrupting the bilayer surface, making the phospholipid molecules more accessible to the enzyme active site.
Collapse
Affiliation(s)
- M J Sheffield
- Department of Zoology, Brigham Young University, Provo, Utah 84602, USA
| | | | | | | | | | | |
Collapse
|
20
|
Pott T, Dufourc EJ. Action of melittin on the DPPC-cholesterol liquid-ordered phase: a solid state 2H-and 31P-NMR study. Biophys J 1995; 68:965-77. [PMID: 7756559 PMCID: PMC1281820 DOI: 10.1016/s0006-3495(95)80272-9] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Solid-state deuterium and phosphorus-31 nuclear magnetic resonance studies of deuterium-labeled beta--[2,2',3,4,4',6-2H6]-cholesterol and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine have been undertaken to monitor the action of melittin on model membranes containing 30 mol% cholesterol, both at the molecular and macroscopic level. Cholesterol totally inhibits the toxin-triggered formation of large unilamellar vesicles and strongly restricts the appearance of small discs. The latter remain stable over a wide temperature range (20-60 degrees C) because of an increase in their cholesterol content as the temperature increases. This process is related to a constant disc hydrophobic thickness of approximately 29 A. The system, when not in the form of discs, appears to be composed of very large vesicles on which melittin promotes magnetically induced ellipsoidal deformation. This deformation is the greatest when the maximum of discs is observed. A model to describe both the disc formation and stability is proposed.
Collapse
Affiliation(s)
- T Pott
- Centre de Recherche Paul Pascal, Centre National de la Recherche Scientifique, Pessac, France
| | | |
Collapse
|
21
|
Otten D, Löbbecke L, Beyer K. Stages of the bilayer-micelle transition in the system phosphatidylcholine-C12E8 as studied by deuterium- and phosphorous-NMR, light scattering, and calorimetry. Biophys J 1995; 68:584-97. [PMID: 7696511 PMCID: PMC1281723 DOI: 10.1016/s0006-3495(95)80220-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The perturbation of phospholipid bilayer membranes by a nonionic detergent, octaethyleneglycol mono-n-dodecylether (C12E8), was investigated by 2H- and 31P-NMR, static and dynamic light scattering, and differential scanning calorimetry. Preequilibrated mixtures of the saturated phospholipids 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC), 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC), and 1,2-dilauroyl-sn-glycero-3-phosphorylcholine (DLPC) with the detergent were studied over a broad temperature range including the temperature of the main thermotropic phase transition of the pure phospholipids. Above this temperature, at a phospholipid/detergent molar ratio 2:1, the membranes were oriented in the magnetic field. Cooling of the mixtures below the thermotropic phase transition temperatures of the pure phospholipids led to micelle formation. In mixtures of DPPC and DMPC with C12E8, a narrow calorimetric signal at the onset temperature of the solubilization suggested that micelle formation was related to the disorder-order transition in the phospholipid acyl chains. The particle size changed from 150 nm to approximately 7 nm over the temperature range of the bilayer-micelle transition. The spontaneous orientation of the membranes at high temperatures enabled the direct determination of segmental order parameters from the deuterium spectra. The order parameter profiles of the phospholipid acyl chains could be attributed to slow fluctuations of the whole membrane and to detergent-induced local perturbations of the bilayer order. The packing constraints in the mixed bilayers that eventually lead to bilayer solubilization were reflected by the order parameters of the interfacial phospholipid acyl chain segments and of the phospholipid headgroup. These results are interpreted in terms of the changing average shape of the component molecules. Considering the decreasing cross sectional areas in the acyl chain region and the increasing hydration of the detergent headgroups, the bilayer-micelle transition is the result of an imbalance in the chain and headgroup repulsion. A neutral or pivotal plane can be defined on the basis of the temperature dependence of the interfacial quadrupolar splittings.
Collapse
Affiliation(s)
- D Otten
- Institut für Physikalische Biochemie, Universität München, Germany
| | | | | |
Collapse
|
22
|
Monette M, Van Calsteren MR, Lafleur M. Effect of cholesterol on the polymorphism of dipalmitoylphosphatidylcholine/melittin complexes: an NMR study. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1149:319-28. [PMID: 8323950 DOI: 10.1016/0005-2736(93)90217-n] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In order to get insights into the effects of cholesterol on protein activity, the lytic power of melittin on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/cholesterol mixtures was studied using solid-state deuterium and phosphorus-31 nuclear magnetic resonance spectroscopy (2H and 31P-NMR). After incubation, melittin disrupts pure DPPC vesicles, leading to the formation of small lipid/peptide complexes below the phase transition temperature (Tm), whereas large bilayer assemblies are reformed above Tm; the transition between these two species is thermally reversible. This study reveals that cholesterol modifies this thermal behavior and that this modulation of the lytic power of melittin is indirect, since it is essentially related to the original effect of the sterol on the thermotropism of pure lipid bilayers. It is known that melittin does not lyse gel phase DPPC bilayers spontaneously. Our study shows that the addition of large amounts of sterol (30 mol%) does not promote the spontaneous lysis at 26 degrees C, despite the increased fluidity of the lipid system. The lysis takes place around 32 degrees C, regardless of the cholesterol concentration. This study also shows that high concentrations of cholesterol (> or = 30%) in DPPC bilayer inhibit the lysis. It is proposed that the tight lipid packing due to high cholesterol concentrations prevents the penetration of melittin into the bilayer. When melittin interacts with cholesterol-rich bilayers (30 mol%), the lysis is only partial, and leads to the formation of small cholesterol-depleted particles. Finally, DPPC which bears deuteriated acyl chains was used to determine the influence of melittin on the orientational order of the lipid chains in the large assemblies. The quadrupolar splittings obtained in the presence of melittin are not considerably different than those obtained in the absence of melittin.
Collapse
Affiliation(s)
- M Monette
- Département de chimie, Université de Montréal, Québec, Canada
| | | | | |
Collapse
|
23
|
Qiu X, Mirau PA, Pidgeon C. Magnetically induced orientation of phosphatidylcholine membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1147:59-72. [PMID: 8466932 DOI: 10.1016/0005-2736(93)90316-r] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Lipid bilayers prepared from natural phospholipids orient in magnetic fields with the long axis of the lipid molecules perpendicular to the magnetic field. This magnetically induced orientation was studied at high (11.7 Tesla (T)), mid (9.36 T), and low (4.68 T) magnetic field strengths using lipid aggregates prepared from natural and synthetic phosphatidylcholine analogs. Phosphatidylcholine analogs containing saturated diacylated chains (12 to 16 carbons/chain) exhibited extensive orientation of the lipid when bilayer formation occurred by gentle hydration conditions. Gentle hydration involved incubating dried phosphatidylcholine C above the main phase transition (Tm); brief shaking or swirling by hand was occasionally needed to completely disperse the lipids. The method of bilayer formation significantly influenced the amount of lipid that orients in magnetic fields. Thus the supramolecular structures (and % orientation) above Tm in an 11.7 T field of dimyristoylphosphatidylcholine (DMPC) bilayers are SUV (0%), LUV (approximately 15%), SPLV (approximately 40%), vortexed-MLV (approximately 60%) and non-vortexed MLV (approximately 90%). Single layered vesicles prepared by the REV method exhibited orientation at 11.7 T similar to LUV prepared by freeze thaw cycles. Aqueous dispersions of eggPC prepared by gentle hydration exhibit approximately 40% orientation at 11.7 T which decreased to approximately 30% orientation if 30% cholesterol is added to the membrane. Magnetic orientation of bilayers thus appears to be a general phenomenon for both saturated and unsaturated natural phospholipids either with or without cholesterol in the membrane.
Collapse
Affiliation(s)
- X Qiu
- Department of Medicinal Chemistry and Pharmacognosy, School of Pharmacy, Purdue University, West Lafayette, IN 47907
| | | | | |
Collapse
|
24
|
Sanders CR, Schaff JE, Prestegard JH. Orientational behavior of phosphatidylcholine bilayers in the presence of aromatic amphiphiles and a magnetic field. Biophys J 1993; 64:1069-80. [PMID: 8494971 PMCID: PMC1262425 DOI: 10.1016/s0006-3495(93)81473-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A number of aromatic-containing additives which can influence the orientation of fragments of lipid bilayer membranes by a magnetic field have been investigated. Two properties of these additives prove important: (1) sufficient detergency to facilitate reorganization of bilayer components and (2), sufficient anisotropy in magnetic susceptibility the preferred direction of fragment orientation. Triton X-100 is identified as effective in terms of facilitating magnetic field ordering of bilayer fragments but does not alter the preferred direction of orientation. A combination of the detergent CHAPSO (3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate) and the aromatic alcohol 1-naphthol facilitates both ordering and alters the preferred direction of bilayer orientation. As mixtures of dimyristoylphosphatidylcholine (DMPC) and CHAPSO, which orient with bilayer normals perpendicular to the magnetic field, were titrated with 1-naphthol, the assemblies underwent transitions, first to random orientation, and then to an orientation with bilayer normals parallel to the field. Based on temperature-induced phase transitions and the extent of motional averaging of the 31P shielding tensor of the DMPC headgroup, the DMPC in these oriented samples appears to maintain a bilayer morphology during transitions. The insight provided in this study regarding factors which influence fragment stability and orientation lays the groundwork for the design of improved field-oriented media for spectroscopic investigation of membrane components.
Collapse
Affiliation(s)
- C R Sanders
- Department of Chemistry, Yale University, New Haven, Connecticut 06511
| | | | | |
Collapse
|