1
|
Clifton LA, Campbell RA, Sebastiani F, Campos-Terán J, Gonzalez-Martinez JF, Björklund S, Sotres J, Cárdenas M. Design and use of model membranes to study biomolecular interactions using complementary surface-sensitive techniques. Adv Colloid Interface Sci 2020; 277:102118. [PMID: 32044469 DOI: 10.1016/j.cis.2020.102118] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/24/2020] [Accepted: 01/29/2020] [Indexed: 01/07/2023]
Abstract
Cellular membranes are complex structures and simplified analogues in the form of model membranes or biomembranes are used as platforms to understand fundamental properties of the membrane itself as well as interactions with various biomolecules such as drugs, peptides and proteins. Model membranes at the air-liquid and solid-liquid interfaces can be studied using a range of complementary surface-sensitive techniques to give a detailed picture of both the structure and physicochemical properties of the membrane and its resulting interactions. In this review, we will present the main planar model membranes used in the field to date with a focus on monolayers at the air-liquid interface, supported lipid bilayers at the solid-liquid interface and advanced membrane models such as tethered and floating membranes. We will then briefly present the principles as well as the main type of information on molecular interactions at model membranes accessible using a Langmuir trough, quartz crystal microbalance with dissipation monitoring, ellipsometry, atomic force microscopy, Brewster angle microscopy, Infrared spectroscopy, and neutron and X-ray reflectometry. A consistent example for following biomolecular interactions at model membranes is used across many of the techniques in terms of the well-studied antimicrobial peptide Melittin. The overall objective is to establish an understanding of the information accessible from each technique, their respective advantages and limitations, and their complementarity.
Collapse
Affiliation(s)
- Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 OQX, United Kingdom
| | - Richard A Campbell
- Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Federica Sebastiani
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden
| | - José Campos-Terán
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana, Unidad Cuajimalpa, Av. Vasco de Quiroga 4871, Col. Santa Fe, Delegación Cuajimalpa de Morelos, 05348, Mexico; Lund Institute of advanced Neutron and X-ray Science, Lund University, Scheelevägen 19, 223 70 Lund, Sweden
| | - Juan F Gonzalez-Martinez
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden
| | - Sebastian Björklund
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden
| | - Javier Sotres
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden
| | - Marité Cárdenas
- Department of Biomedical Science and Biofilms - Research Center for Biointerfaces, Malmö University, 20506 Malmö, Sweden.
| |
Collapse
|
2
|
Protocol for Investigating the Interactions Between Intrinsically Disordered Proteins and Membranes by Neutron Reflectometry. Methods Mol Biol 2020; 2141:569-584. [PMID: 32696378 DOI: 10.1007/978-1-0716-0524-0_29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Several intrinsically disordered proteins (IDPs) exhibit high affinity for lipid membranes. Among the different biophysical methods to probe protein-lipid interaction, neutron reflectometry (NR) can provide direct and structural detailed information on the location of the IDP with respect to the membrane. Supported lipid bilayers are commonly used as cell membrane models in such experiments. NR measurements can be collected on the supported lipid bilayer before and after the interaction with the IDP to characterize whether the protein molecules are mainly located on the membrane surface (interaction with the lipid headgroups), are penetrating into the hydrophobic region of the membrane (interaction with the lipid acyl chains), or are not interacting at all with the membrane. The lipid composition of the supported lipid bilayer can easily be tuned; hence the NR experiments can be designed to investigate selective IDP-lipid interactions.This chapter will describe the fundamental steps for performing an NR experiment and the subsequent data analysis aimed at characterizing IDP-lipid bilayer interactions. The specific case of an intrinsically disordered region (IDR) from the membrane protein Na+/H+ exchanger isoform 1 (NHE1) will be used as an example, but the same protocol can be easily adapted to other IDPs.
Collapse
|
3
|
Yu H, Yzeiri I, Hou B, Chen CH, Bu W, Vanysek P, Chen YS, Lin B, Král P, Schlossman ML. Electric Field Effect on Phospholipid Monolayers at an Aqueous-Organic Liquid-Liquid Interface. J Phys Chem B 2014; 119:9319-34. [PMID: 25289837 DOI: 10.1021/jp5098525] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electric potential difference across cell membranes, known as the membrane potential, plays an important role in the activation of many biological processes. To investigate the effect of the membrane potential on the molecular ordering of lipids within a biomimetic membrane, a self-assembled monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) lipids at an electrified 1,2-dichloroethane/water interface is studied with X-ray reflectivity and interfacial tension. Measurements over a range of electric potential differences, -150 to +130 mV, that encompass the range of typical biomembrane potentials demonstrate a nearly constant and stable structure whose lipid interfacial density is comparable to that found in other biomimetic membrane systems. Measurements at higher positive potentials, up to 330 mV, illustrate a monotonic decrease in the lipid interfacial density and accompanying variations in the interfacial configuration of the lipid. Molecular dynamics simulations, designed to mimic the experimental conditions, show that the measured changes in lipid configuration are due primarily to the variation in area per lipid with increasing applied electric field. Rotation of the SOPC dipole moment by the torque from the applied electric field appears to be negligible, except at the highest measured potentials. The simulations confirm in atomistic detail the measured potential-dependent characteristics of SOPC monolayers. Our hybrid study sheds light on phospholipid monolayer stability under different membrane potentials, which is important for understanding membrane processes. This study also illustrates the use of X-ray surface scattering to probe the ordering of surfactant monolayers at an electrified aqueous-organic liquid-liquid interface.
Collapse
Affiliation(s)
- Hao Yu
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Irena Yzeiri
- ‡Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Binyang Hou
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Chiu-Hao Chen
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Wei Bu
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | | | - Yu-Sheng Chen
- ∥The Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States
| | - Binhua Lin
- ∥The Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States
| | - Petr Král
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States.,‡Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Mark L Schlossman
- †Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| |
Collapse
|
4
|
Andreev K, Bianchi C, Laursen JS, Citterio L, Hein-Kristensen L, Gram L, Kuzmenko I, Olsen CA, Gidalevitz D. Guanidino groups greatly enhance the action of antimicrobial peptidomimetics against bacterial cytoplasmic membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2492-2502. [PMID: 24878450 DOI: 10.1016/j.bbamem.2014.05.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 05/11/2014] [Accepted: 05/19/2014] [Indexed: 11/18/2022]
Abstract
Antimicrobial peptides or their synthetic mimics are a promising class of potential new antibiotics. Herein we assess the effect of the type of cationic side chain (i.e., guanidino vs. amino groups) on the membrane perturbing mechanism of antimicrobial α-peptide-β-peptoid chimeras. Langmuir monolayers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylglycerol (DPPG) were used to model cytoplasmic membranes of both Gram-positive and Gram-negative bacteria, while lipopolysaccharide Kdo2-lipid A monolayers were mimicking the outer membrane of Gram-negative species. We report the results of the measurements using an array of techniques, including high-resolution synchrotron surface X-ray scattering, epifluorescence microscopy, and in vitro antimicrobial activity to study the molecular mechanisms of peptidomimetic interaction with bacterial membranes. We found guanidino group-containing chimeras to exhibit greater disruptive activity on DPPG monolayers than the amino group-containing analogues. However, this effect was not observed for lipopolysaccharide monolayers where the difference was negligible. Furthermore, the addition of the nitrobenzoxadiazole fluorophore did not reduce the insertion activity of these antimicrobials into both model membrane systems examined, which may be useful for future cellular localization studies.
Collapse
Affiliation(s)
- Konstantin Andreev
- Center for Molecular Study of Condensed Soft Matter (μCoSM), Pritzker Institute of Biomedical Science and Engineering and Department of Physics, Illinois Institute of Technology, 3440 S. Dearborn St., Chicago, IL 60616 (USA)
| | - Christopher Bianchi
- Center for Molecular Study of Condensed Soft Matter (μCoSM), Pritzker Institute of Biomedical Science and Engineering and Department of Physics, Illinois Institute of Technology, 3440 S. Dearborn St., Chicago, IL 60616 (USA)
| | - Jonas S Laursen
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, DK-2800 Kgs. Lyngby (Denmark)
| | - Linda Citterio
- Department of Systems Biology, Technical University of Denmark, Matematiktorvet 301, DK-2800 Kgs. Lyngby (Denmark)
| | - Line Hein-Kristensen
- , National Food Institute, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kgs Lyngby (Denmark)
| | - Lone Gram
- Department of Systems Biology, Technical University of Denmark, Matematiktorvet 301, DK-2800 Kgs. Lyngby (Denmark)
| | - Ivan Kuzmenko
- Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Lemont, IL 60439 (USA)
| | - Christian A Olsen
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, DK-2800 Kgs. Lyngby (Denmark)
| | - David Gidalevitz
- Center for Molecular Study of Condensed Soft Matter (μCoSM), Pritzker Institute of Biomedical Science and Engineering and Department of Physics, Illinois Institute of Technology, 3440 S. Dearborn St., Chicago, IL 60616 (USA)
| |
Collapse
|
5
|
Hąc-Wydro K, Flasiński M, Broniatowski M, Dynarowicz-Łątka P, Majewski J. Comparative Studies on the Influence of β-Sitosterol and Stigmasterol on Model Sphingomyelin Membranes: A Grazing-Incidence X-ray Diffraction Study. J Phys Chem B 2010; 114:6866-71. [DOI: 10.1021/jp101196e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Katarzyna Hąc-Wydro
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland, and Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | - Michał Flasiński
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland, and Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | - Marcin Broniatowski
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland, and Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | - Patrycja Dynarowicz-Łątka
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland, and Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | - Jarosław Majewski
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland, and Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| |
Collapse
|
6
|
Neville F, Ivankin A, Konovalov O, Gidalevitz D. A comparative study on the interactions of SMAP-29 with lipid monolayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:851-60. [PMID: 19800862 DOI: 10.1016/j.bbamem.2009.09.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 09/08/2009] [Accepted: 09/24/2009] [Indexed: 11/26/2022]
Abstract
This work investigates the discrimination of lipid monolayers by the ovine antimicrobial peptide SMAP-29 and compares it to that of the human LL-37 peptide. Fluid phospholipid monolayers were formed in a Langmuir trough and subsequently studied with the X-ray scattering techniques of X-ray reflectivity and grazing incidence X-ray diffraction. Any changes in the phospholipid structure after injection of peptide under the monolayer were considered to be due to interactions between the peptides and lipids. The data show that SMAP-29 discriminates against negatively charged phospholipids in a similar way to LL-37. However, it is even more interesting to note that despite a higher concentration of SMAP-29 near the monolayer, ensured by its greater charge as compared to LL-37, the amount of SMAP-29 needed to observe monolayer disruption was around three and a half times the number of molecules of LL-37 used to see similar changes with the same system. This result suggests that the structure, amino acid sequence or size of the peptide may well be as important as electrical charge and therefore gives many implications for the further study of antimicrobial peptides with regards to novel drug design and development.
Collapse
Affiliation(s)
- Frances Neville
- School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS29JT, UK
| | | | | | | |
Collapse
|
7
|
Nickolov ZS, Britt DW, Miller JD. Sum-frequency spectroscopy analysis of two-component langmuir monolayers and the associated interfacial water structure. J Phys Chem B 2007; 110:15506-13. [PMID: 16884274 DOI: 10.1021/jp0631578] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sum-frequency spectroscopy (SFS) in the CH and OH stretching regions was employed to obtain structural information about Langmuir monolayers on the H(2)O subphase of the model lipid dioctadecyldimethylammonium bromide (DOMA) and of the neutral surfactant methyl stearate (SME) and their mixtures and about the interfacial water structure underneath the films. These results were compared with the sum-frequency spectra of the interface between Langmuir monolayers of stearic acid and stearic acid-DOMA monolayers and water to prove that the uncompensated headgroup charge of DOMA at the interface is the reason for structuring of interfacial water close to the studied monomolecular films. Sum-frequency spectra on D(2)O subphase were also studied to account for the interference between the CH and OH spectral signatures because of the coherent nature of the SFS signals. Interfacial water structure proved to be a determining factor in the behavior of the mixed lipid monolayers. A mixing induced amplification in the surface potential DeltaV observed in our previous work was explained with total increase of the dipole moment for the mixed films, bigger than the arithmetic average for DOMA and SME monolayers alone. The increase is due to the better packing of the molecules in the mixed films and to the decrease in the interfacial water dipole moment arising from a more disordered water structure underneath the mixed monolayers.
Collapse
Affiliation(s)
- Zhorro S Nickolov
- Department of Materials Science and Engineering, A. J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, Pennsylvania 19104, USA.
| | | | | |
Collapse
|
8
|
Constantin D, Brotons G, Jarre A, Li C, Salditt T. Interaction of alamethicin pores in DMPC bilayers. Biophys J 2007; 92:3978-87. [PMID: 17369412 PMCID: PMC1868975 DOI: 10.1529/biophysj.106.101204] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have investigated the x-ray scattering signal of highly aligned multilayers of the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine containing pores formed by the antimicrobial peptide alamethicin as a function of the peptide/lipid ratio. We are able to obtain information on the structure factor of the pore fluid, which then yields the interaction potential between pores in the plane of the bilayers. Aside from a hard core with a radius corresponding to the geometric radius of the pore, we find a repulsive lipid-mediated interaction with a range of approximately 30 A and a contact value of 2.4 k(B)T. This result is in qualitative agreement with recent theoretical models.
Collapse
|
9
|
Volinsky R, Kolusheva S, Berman A, Jelinek R. Investigations of antimicrobial peptides in planar film systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1393-407. [PMID: 16793000 DOI: 10.1016/j.bbamem.2006.03.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2006] [Revised: 03/03/2006] [Accepted: 03/05/2006] [Indexed: 11/30/2022]
Abstract
Planar systems--monolayers and films--constitute a useful platform for studying membrane-active peptides. Here, we summarize varied approaches for studying peptide organization and peptide-lipid interactions at the air/water interface, and focus on three representative antimicrobial membrane--associated peptides-alamethicin, gramicidin, and valinomycin. Experimental data, specifically surface pressure/area isotherms and Brewster angle microscopy images, provided information on peptide association and the effects of the lipid monolayers on peptide surface organization. In general, film analysis emphasized the effects of lipid layers in promoting peptide association and aggregation at the air/water interface. Importantly, the data demonstrated that in many cases peptide domains are phase-separated within the phospholipid monolayers, suggesting that this behavior contributes to the biological actions of membrane-active antimicrobial peptides.
Collapse
Affiliation(s)
- Roman Volinsky
- Department of Chemistry, and the Ilse Katz Center for Nanotechnology, Ben Gurion University of the Negev, Beer Sheva 84103, Israel
| | | | | | | |
Collapse
|
10
|
Salditt T, Li C, Spaar A. Structure of antimicrobial peptides and lipid membranes probed by interface-sensitive X-ray scattering. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1483-98. [DOI: 10.1016/j.bbamem.2006.08.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2006] [Revised: 08/04/2006] [Accepted: 08/04/2006] [Indexed: 10/24/2022]
|
11
|
Sengupta K, Limozin L, Tristl M, Haase I, Fischer M, Sackmann E. Coupling artificial actin cortices to biofunctionalized lipid monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:5776-85. [PMID: 16768508 DOI: 10.1021/la053310+] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We report the assembly of protein supramolecular structures at an air-water interface and coupling of artificial actin cortices to such structures. The coupling strategies adopted include electrostatic binding of actin to monolayers doped with lipids, exposing positively charged poly(ethylene glycol) headgroups; binding of biotinylated actin to lipids carrying biotin headgroups through avidin; binding of actin to membranes through biotinylated hisactophilin (a cellular actin-membrane coupler) using an avidin-biotin linkage; and coupling of actin to membranes carrying chelating lipids through a 15-nm-diameter protein capsid (bacterial lumazine synthase or LuSy) exhibiting histidine tags (which bind both to actin and to the chelating lipid). The distribution of the proteins in a direction normal to the interface was measured by neutron reflectivity under different conditions of pH and ionic strength. In the case of the first three binding methods, the thickness of the actin film was found to correspond to a single actin filament. Multilayers of actin could be formed only by using the multifunctional LuSy couplers that exhibit 60 hexahistidine tags and can thus act as actin cross-linkers. The LuSy-mediated binding can be reversibly switched by pH variations.
Collapse
Affiliation(s)
- Kheya Sengupta
- Lehrstuhl für Biophysik, E22, Technische Universität München, James-Franck-Strasse 1, D-85748 Garching, Germany.
| | | | | | | | | | | |
Collapse
|
12
|
Neville F, Hodges CS, Liu C, Konovalov O, Gidalevitz D. In situ characterization of lipid A interaction with antimicrobial peptides using surface X-ray scattering. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:232-40. [PMID: 16584708 DOI: 10.1016/j.bbamem.2006.01.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 01/29/2006] [Accepted: 01/31/2006] [Indexed: 11/23/2022]
Abstract
Lipid A structure at the air-aqueous interface has been studied using pressure-area isotherm methods coupled with the surface X-ray scattering techniques of X-ray reflectivity (XR) and grazing incidence X-ray diffraction (GIXD). Lipid A monolayers were formed at the air-aqueous interface to represent the lipid moiety of the outer membrane of Gram-negative bacteria. Lipid A structure was characterized at surface pressures between 10 and 35 mN/m. Interactions of alpha-helical antimicrobial peptides LL-37, SMAP-29 and D2A22 with lipid A monolayers were subsequently studied. Although insertion into the lipid A monolayers was observed with the alpha-helical peptides, little change was seen from the X-ray data, suggesting that the lipid A hydrocarbon chains are involved in reorientation during insertion and that the hydrocarbon chains have a relatively rigid structure.
Collapse
Affiliation(s)
- Frances Neville
- School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT, UK
| | | | | | | | | |
Collapse
|
13
|
Neville F, Cahuzac M, Konovalov O, Ishitsuka Y, Lee KYC, Kuzmenko I, Kale GM, Gidalevitz D. Lipid headgroup discrimination by antimicrobial peptide LL-37: insight into mechanism of action. Biophys J 2006; 90:1275-87. [PMID: 16299073 PMCID: PMC1367279 DOI: 10.1529/biophysj.105.067595] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Accepted: 09/29/2005] [Indexed: 11/18/2022] Open
Abstract
Interaction of the human antimicrobial peptide LL-37 with lipid monolayers has been investigated by a range of complementary techniques including pressure-area isotherms, insertion assay, epifluorescence microscopy, and synchrotron x-ray scattering, to analyze its mechanism of action. Lipid monolayers were formed at the air-liquid interface to mimic the surface of the bacterial cell wall and the outer leaflet of erythrocyte cell membrane by using phosphatidylglycerol (DPPG), phosphatidylcholine (DPPC), and phosphatidylethanolamine (DPPE) lipids. LL-37 is found to readily insert into DPPG monolayers, disrupting their structure and thus indicating bactericidal action. In contrast, DPPC and DPPE monolayers remained virtually unaffected by LL-37, demonstrating its nonhemolytic activity and lipid discrimination. Specular x-ray reflectivity data yielded considerable differences in layer thickness and electron-density profile after addition of the peptide to DPPG monolayers, but little change was seen after peptide injection when probing monolayers composed of DPPC and DPPE. Grazing incidence x-ray diffraction demonstrated significant peptide insertion and lateral packing order disruption of the DPPG monolayer by LL-37 insertion. Epifluorescence microscopy data support these findings.
Collapse
Affiliation(s)
- Frances Neville
- Institute for Materials Research, University of Leeds, Leeds, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Salditt T. Lipid-peptide interaction in oriented bilayers probed by interface-sensitive scattering methods. Curr Opin Struct Biol 2003; 13:467-78. [PMID: 12948776 DOI: 10.1016/s0959-440x(03)00113-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Oriented lipid membranes deposited on solid substrates offer unique experimental opportunities to study lipid bilayer structure and lipid-peptide interaction in suitable model systems. In particular, modern interface-sensitive X-ray and neutron scattering methods can be used to probe the short-range order and molecular conformations of peptides and lipids in the fluid state of the bilayer.
Collapse
Affiliation(s)
- Tim Salditt
- Institüt für Röntgenphysik, Universität Göttingen, Geiststrasse 11, D-37037 Göttingen, Germany.
| |
Collapse
|