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Gao X, Ding J, Liao C, Xu J, Liu X, Lu W. Defensins: The natural peptide antibiotic. Adv Drug Deliv Rev 2021; 179:114008. [PMID: 34673132 DOI: 10.1016/j.addr.2021.114008] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/28/2021] [Accepted: 10/12/2021] [Indexed: 12/12/2022]
Abstract
Defensins are a family of cationic antimicrobial peptides active against a broad range of infectious microbes including bacteria, viruses and fungi, playing important roles as innate effectors and immune modulators in immunological control of microbial infection. Their antibacterial properties and unique mechanisms of action have garnered considerable interest in developing defensins into a novel class of natural antibiotic peptides to fend off pathogenic infection by bacteria, particularly those resistant to conventional antibiotics. However, serious pharmacological and technical obstacles, some of which are unique to defensins and others are common to peptide drugs in general, have hindered the development and clinical translation of defensins as anti-infective therapeutics. To overcome them, several technologies have been developed, aiming for improved functionality, prolonged circulation time, enhanced proteolytic stability and bioavailability, and efficient and controlled delivery and release of defensins to the site of infection. Additional challenges include the alleviation of potential toxicity of defensins and their cost-effective manufacturing. In this review, we briefly introduce defensin biology, focus on various transforming strategies and practical techniques developed for defensins and their derivatives as antibacterial therapeutics, and conclude with a summation of future challenges and possible solutions.
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Zong X, Fu J, Xu B, Wang Y, Jin M. Interplay between gut microbiota and antimicrobial peptides. ANIMAL NUTRITION (ZHONGGUO XU MU SHOU YI XUE HUI) 2020; 6:389-396. [PMID: 33364454 PMCID: PMC7750803 DOI: 10.1016/j.aninu.2020.09.002] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/09/2020] [Accepted: 09/14/2020] [Indexed: 12/19/2022]
Abstract
The gut microbiota is comprised of a diverse array of microorganisms that interact with immune system and exert crucial roles for the health. Changes in the gut microbiota composition and functionality are associated with multiple diseases. As such, mobilizing a rapid and appropriate antimicrobial response depending on the nature of each stimulus is crucial for maintaining the balance between homeostasis and inflammation in the gut. Major players in this scenario are antimicrobial peptides (AMP), which belong to an ancient defense system found in all organisms and participate in a preservative co-evolution with a complex microbiome. Particularly increasing interactions between AMP and microbiota have been found in the gut. Here, we focus on the mechanisms by which AMP help to maintain a balanced microbiota and advancing our understanding of the circumstances of such balanced interactions between gut microbiota and host AMP. This review aims to provide a comprehensive overview on the interplay of diverse antimicrobial responses with enteric pathogens and the gut microbiota, which should have therapeutic implications for different intestinal disorders.
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Affiliation(s)
- Xin Zong
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jie Fu
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Bocheng Xu
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yizhen Wang
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Mingliang Jin
- Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
- Key Laboratory of Animal Nutrition and Feed Science in Eastern China, Ministry of Agriculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
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Rabe M, Aisenbrey C, Pluhackova K, de Wert V, Boyle AL, Bruggeman DF, Kirsch SA, Böckmann RA, Kros A, Raap J, Bechinger B. A Coiled-Coil Peptide Shaping Lipid Bilayers upon Fusion. Biophys J 2016; 111:2162-2175. [PMID: 27851940 PMCID: PMC5113151 DOI: 10.1016/j.bpj.2016.10.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/08/2016] [Accepted: 10/06/2016] [Indexed: 12/19/2022] Open
Abstract
A system based on two designed peptides, namely the cationic peptide K, (KIAALKE)3, and its complementary anionic counterpart called peptide E, (EIAALEK)3, has been used as a minimal model for membrane fusion, inspired by SNARE proteins. Although the fact that docking of separate vesicle populations via the formation of a dimeric E/K coiled-coil complex can be rationalized, the reasons for the peptides promoting fusion of vesicles cannot be fully explained. Therefore it is of significant interest to determine how the peptides aid in overcoming energetic barriers during lipid rearrangements leading to fusion. In this study, investigations of the peptides' interactions with neutral PC/PE/cholesterol membranes by fluorescence spectroscopy show that tryptophan-labeled K∗ binds to the membrane (KK∗ ∼6.2 103 M-1), whereas E∗ remains fully water-solvated. 15N-NMR spectroscopy, depth-dependent fluorescence quenching, CD-spectroscopy experiments, and MD simulations indicate a helix orientation of K∗ parallel to the membrane surface. Solid-state 31P-NMR of oriented lipid membranes was used to study the impact of peptide incorporation on lipid headgroup alignment. The membrane-immersed K∗ is found to locally alter the bilayer curvature, accompanied by a change of headgroup orientation relative to the membrane normal and of the lipid composition in the vicinity of the bound peptide. The NMR results were supported by molecular dynamics simulations, which showed that K reorganizes the membrane composition in its vicinity, induces positive membrane curvature, and enhances the lipid tail protrusion probability. These effects are known to be fusion relevant. The combined results support the hypothesis for a twofold role of K in the mechanism of membrane fusion: 1) to bring opposing membranes into close proximity via coiled-coil formation and 2) to destabilize both membranes thereby promoting fusion.
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Affiliation(s)
- Martin Rabe
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands.
| | | | - Kristyna Pluhackova
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Vincent de Wert
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Aimee L Boyle
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Didjay F Bruggeman
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Sonja A Kirsch
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Rainer A Böckmann
- Computational Biology, Department of Biology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Alexander Kros
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Jan Raap
- Leiden Institute of Chemistry - Supramolecular and Biomaterials Chemistry, Leiden University, Leiden, the Netherlands
| | - Burkhard Bechinger
- Université de Strasbourg/CNRS UMR7177, Institut de Chimie, Strasbourg, France.
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Wang CK, King GJ, Conibear AC, Ramos MC, Chaousis S, Henriques ST, Craik DJ. Mirror Images of Antimicrobial Peptides Provide Reflections on Their Functions and Amyloidogenic Properties. J Am Chem Soc 2016; 138:5706-13. [PMID: 27064294 DOI: 10.1021/jacs.6b02575] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Enantiomeric forms of BTD-2, PG-1, and PM-1 were synthesized to delineate the structure and function of these β-sheet antimicrobial peptides. Activity and lipid-binding assays confirm that these peptides act via a receptor-independent mechanism involving membrane interaction. The racemic crystal structure of BTD-2 solved at 1.45 Å revealed a novel oligomeric form of β-sheet antimicrobial peptides within the unit cell: an antiparallel trimer, which we suggest might be related to its membrane-active form. The BTD-2 oligomer extends into a larger supramolecular state that spans the crystal lattice, featuring a steric-zipper motif that is common in structures of amyloid-forming peptides. The supramolecular structure of BTD-2 thus represents a new mode of fibril-like assembly not previously observed for antimicrobial peptides, providing structural evidence linking antimicrobial and amyloid peptides.
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Affiliation(s)
- Conan K Wang
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Gordon J King
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Anne C Conibear
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Mariana C Ramos
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Stephanie Chaousis
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Sónia Troeira Henriques
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
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Fillion M, Auger M. Oriented samples: a tool for determining the membrane topology and the mechanism of action of cationic antimicrobial peptides by solid-state NMR. Biophys Rev 2015; 7:311-320. [PMID: 28510228 PMCID: PMC5425733 DOI: 10.1007/s12551-015-0167-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 02/05/2015] [Indexed: 01/12/2023] Open
Abstract
Overuse and misuse of antibiotics have led bacteria to acquire several mechanisms of resistance. In response to this, researchers have identified natural antimicrobial peptides as promising candidates to fight against multiresistant bacteria. However, their mode of action is still unclear, and a better understanding of the mode of action of these peptides is of primary importance to develop new peptides displaying high antibacterial activity and low hemolytic activity. One of the main features that defines the mechanism of action is the membrane topology of the peptide. Among the spectroscopic techniques, solid-state NMR is the technique of choice for determining the location of the peptide within the membrane. It can be achieved by performing experiments with oriented samples. In the literature, the two most common types of oriented samples are bicelles and phospholipids mechanically oriented between glass plates. The mode of perturbation of the membrane-active peptide can be studied by phosphorus-31 and deuterium NMR. On the other hand, several experiments such as nitrogen-15 and fluorine solid-state NMR, that require labeled peptides, can give valuable information on the membrane topology of the peptide. The combination of the latter techniques allows the determination of a precise topology, thus a better knowledge of the molecular determinants involved in the membrane interactions of antimicrobial peptides.
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Affiliation(s)
- Matthieu Fillion
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Centre québécois sur les matériaux fonctionnels (CQMF), Université Laval, Québec, QC, G1V 0A6, Canada
| | - Michèle Auger
- Department of Chemistry, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Centre québécois sur les matériaux fonctionnels (CQMF), Université Laval, Québec, QC, G1V 0A6, Canada.
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Investigations of the synergistic enhancement of antimicrobial activity in mixtures of magainin 2 and PGLa. Biophys Chem 2015; 210:35-44. [PMID: 26099623 DOI: 10.1016/j.bpc.2015.06.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 05/28/2015] [Accepted: 06/01/2015] [Indexed: 02/07/2023]
Abstract
Magainins are antimicrobial peptides isolated from the African clawed frog Xenopus laevis. They interact with bacterial membranes where they cause channel formation and membrane disruption. When added as a cocktail magainin 2 and PGLa are considerably more efficient when compared to the corresponding amounts of individual components. In order to investigate this synergistic interaction of PGLa and magainin a number of magainin variants have been prepared and investigated in biological and biophysical assays. In particular we report on the antimicrobial activities and solid-state NMR investigations of magainins that have been extended by a carboxyterminal GGC tripeptide to form covalently linked dimers. Notably, when the formation of the covalent linkage is prevented by exchanging the cystein by serine or alanine no loss in efficiency was observed indicating that the covalent interaction is not necessary for synergistic interaction. In a next step peptides labelled with (15)N and (2)H were reconstituted into oriented membranes and their topology studied by solid-state NMR spectroscopy. The tendency of some of these peptides to adopt membrane-spanning alignments does not correlate with their synergistic activities in antimicrobial assays. In contrast, the stable alignment of PGLa parallel to the surface of membranes made of Escherichia coli lipid extracts is strongly suggestive that the peptides develop synergistic activities when in an in-planar configuration. Notably, the phospholipid head groups of these samples show a high degree of disturbance suggesting that the synergistic interactions between the magainin peptides could be mediated through the lipid phase.
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Choi H, Kim C. Effect of Cholesterol on the Phase Change of Lipid Membranes by Antimicrobial Peptides. B KOREAN CHEM SOC 2014. [DOI: 10.5012/bkcs.2014.35.5.1317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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8
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Kim C. A solid-state NMR study on the hydration effect on the lipid phase change in the presence of an antimicrobial peptide. ANALYTICAL SCIENCE AND TECHNOLOGY 2013. [DOI: 10.5806/ast.2013.26.6.395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Giese M, De Witt JC, Shopsowitz KE, Manning AP, Dong RY, Michal CA, Hamad WY, MacLachlan MJ. Thermal switching of the reflection in chiral nematic mesoporous organosilica films infiltrated with liquid crystals. ACS APPLIED MATERIALS & INTERFACES 2013; 5:6854-6859. [PMID: 23859140 DOI: 10.1021/am402266z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Materials that undergo stimulus-induced optical changes are important for many new technologies. In this paper, we describe a new free-standing silica-based composite film that exhibits reversible thermochromic reflection, induced by a liquid crystalline guest in the pores of iridescent mesoporous films. We demonstrate that selective reflection from the novel mesoporous organosilica material with chiral nematic organization can be reversibly switched by thermal cycling of the 8CB guest between its isotropic and liquid crystalline states, which was proven by solid-state NMR experiments. The switching of the optical properties of the chiral solid-state host by stimulus-induced transitions of the guest opens the possibility of applications for these novel materials in sensors and displays.
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Affiliation(s)
- Michael Giese
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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Su Y, Li S, Hong M. Cationic membrane peptides: atomic-level insight of structure-activity relationships from solid-state NMR. Amino Acids 2013; 44:821-33. [PMID: 23108593 PMCID: PMC3570695 DOI: 10.1007/s00726-012-1421-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 10/11/2012] [Indexed: 12/24/2022]
Abstract
Many membrane-active peptides, such as cationic cell-penetrating peptides (CPPs) and antimicrobial peptides (AMPs), conduct their biological functions by interacting with the cell membrane. The interactions of charged residues with lipids and water facilitate membrane insertion, translocation or disruption of these highly hydrophobic species. In this review, we will summarize high-resolution structural and dynamic findings towards the understanding of the structure-activity relationship of lipid membrane-bound CPPs and AMPs, as examples of the current development of solid-state NMR (SSNMR) techniques for studying membrane peptides. We will present the most recent atomic-resolution structure of the guanidinium-phosphate complex, as constrained from experimentally measured site-specific distances. These SSNMR results will be valuable specifically for understanding the intracellular translocation pathway of CPPs and antimicrobial mechanism of AMPs, and more generally broaden our insight into how cationic macromolecules interact with and cross the lipid membrane.
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Affiliation(s)
- Yongchao Su
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA.
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11
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Choi HG, Kim C. A 2H solid-state NMR study on the lipid phase change in the presence of an antimicrobial peptide. ANALYTICAL SCIENCE AND TECHNOLOGY 2013. [DOI: 10.5806/ast.2013.26.1.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Kim C, Wi S. A Solid-state NMR Study of the Kinetics of the Activity of an Antimicrobial Peptide, PG-1 on Lipid Membranes. B KOREAN CHEM SOC 2012. [DOI: 10.5012/bkcs.2012.33.2.426] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Kim C. A solid-state NMR study on the activity of an antimicrobial peptide, magainin 2. ANALYTICAL SCIENCE AND TECHNOLOGY 2011. [DOI: 10.5806/ast.2011.24.6.460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Lam KLH, Wang H, Siaw TA, Chapman MR, Waring AJ, Kindt JT, Lee KYC. Mechanism of structural transformations induced by antimicrobial peptides in lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:194-204. [PMID: 22100601 DOI: 10.1016/j.bbamem.2011.11.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 11/01/2011] [Accepted: 11/02/2011] [Indexed: 01/14/2023]
Abstract
It has long been suggested that pore formation is responsible for the increase in membrane permeability by antimicrobial peptides (AMPs). To better understand the mechanism of AMP activity, the disruption of model membrane by protegrin-1 (PG-1), a cationic antimicrobial peptide, was studied using atomic force microscopy. We present here the direct visualization of the full range of structural transformations in supported lipid bilayer patches induced by PG-1 on zwitterionic 1,2-dimyristoyl-snglycero-phospho-choline (DMPC) membranes. When PG-1 is added to DMPC, the peptide first induces edge instability at low concentrations, then pore-like surface defects at intermediate concentrations, and finally wormlike structures with a specific length scale at high concentrations. The formation of these structures can be understood using a mesophase framework of a binary mixture of lipids and peptides, where PG-1 acts as a line-active agent. Atomistic molecular dynamics simulations on lipid bilayer ribbons with PG-1 molecules placed at the edge or interior positions are carried out to calculate the effect of PG-1 in reducing line tension. Further investigation of the placement of PG-1 and its association with defects in the bilayer is carried out using unbiased assembly of a PG-1 containing bilayer from a random mixture of PG-1, DMPC, and water. A generalized model of AMP induced structural transformations is also presented in this work. This article is part of a Special Issue entitled: Membrane protein structure and function.
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Affiliation(s)
- Kin Lok H Lam
- Department of Physics, The University of Chicago, Chicago, IL, USA
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15
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Kwon T, Harris AL, Rossi A, Bargiello TA. Molecular dynamics simulations of the Cx26 hemichannel: evaluation of structural models with Brownian dynamics. J Gen Physiol 2011; 138:475-93. [PMID: 22006989 PMCID: PMC3206306 DOI: 10.1085/jgp.201110679] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 09/27/2011] [Indexed: 11/21/2022] Open
Abstract
The recently published crystal structure of the Cx26 gap junction channel provides a unique opportunity for elucidation of the structure of the conductive connexin pore and the molecular determinants of its ion permeation properties (conductance, current-voltage [I-V] relations, and charge selectivity). However, the crystal structure was incomplete, most notably lacking the coordinates of the N-terminal methionine residue, which resides within the pore, and also lacking two cytosolic domains. To allow computational studies for comparison with the known channel properties, we completed the structure. Grand canonical Monte Carlo Brownian dynamics (GCMC/BD) simulations of the completed and the published Cx26 hemichannel crystal structure indicate that the pore is too narrow to permit significant ion flux. The GCMC/BD simulations predict marked inward current rectification and almost perfect anion selectivity, both inconsistent with known channel properties. The completed structure was refined by all-atom molecular dynamics (MD) simulations (220 ns total) in an explicit solvent and POPC membrane system. These MD simulations produced an equilibrated structure with a larger minimal pore diameter, which decreased the height of the permeation barrier formed by the N terminus. GCMC/BD simulations of the MD-equilibrated structure yielded more appropriate single-channel conductance and less anion/cation selectivity. However, the simulations much more closely matched experimentally determined I-V relations when the charge effects of specific co- and posttranslational modifications of Cx26 previously identified by mass spectrometry were incorporated. We conclude that the average equilibrated structure obtained after MD simulations more closely represents the open Cx26 hemichannel structure than does the crystal structure, and that co- and posttranslational modifications of Cx26 hemichannels are likely to play an important physiological role by defining the conductance and ion selectivity of Cx26 channels. Furthermore, the simulations and data suggest that experimentally observed heterogeneity in Cx26 I-V relations can be accounted for by variation in co- and posttranslational modifications.
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Affiliation(s)
- Taekyung Kwon
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Andrew L. Harris
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103
| | - Angelo Rossi
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103
| | - Thaddeus A. Bargiello
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
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Pignatello R, Musumeci T, Basile L, Carbone C, Puglisi G. Biomembrane models and drug-biomembrane interaction studies: Involvement in drug design and development. J Pharm Bioallied Sci 2011; 3:4-14. [PMID: 21430952 PMCID: PMC3053521 DOI: 10.4103/0975-7406.76461] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 09/18/2010] [Accepted: 12/11/2010] [Indexed: 12/19/2022] Open
Abstract
Contact with many different biological membranes goes along the destiny of a drug after its systemic administration. From the circulating macrophage cells to the vessel endothelium, to more complex absorption barriers, the interaction of a biomolecule with these membranes largely affects its rate and time of biodistribution in the body and at the target sites. Therefore, investigating the phenomena occurring on the cell membranes, as well as their different interaction with drugs in the physiological or pathological conditions, is important to exploit the molecular basis of many diseases and to identify new potential therapeutic strategies. Of course, the complexity of the structure and functions of biological and cell membranes, has pushed researchers toward the proposition and validation of simpler two- and three-dimensional membrane models, whose utility and drawbacks will be discussed. This review also describes the analytical methods used to look at the interactions among bioactive compounds with biological membrane models, with a particular accent on the calorimetric techniques. These studies can be considered as a powerful tool for medicinal chemistry and pharmaceutical technology, in the steps of designing new drugs and optimizing the activity and safety profile of compounds already used in the therapy.
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Affiliation(s)
- R Pignatello
- Department of Drug Sciences, University of Catania, viale A. Doria, 6 - 95125 Catania, Italy
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Su Y, Waring AJ, Ruchala P, Hong M. Structures of β-hairpin antimicrobial protegrin peptides in lipopolysaccharide membranes: mechanism of gram selectivity obtained from solid-state nuclear magnetic resonance. Biochemistry 2011; 50:2072-83. [PMID: 21302955 PMCID: PMC3062705 DOI: 10.1021/bi101975v] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structural basis for the gram selectivity of two disulfide-bonded β-hairpin antimicrobial peptides (AMPs) is investigated using solid-state nuclear magnetic resonance (NMR) spectroscopy. The hexa-arginine PG-1 exhibits potent activities against both gram-positive and gram-negative bacteria, while a mutant of PG-1 with only three cationic residues maintains gram-positive activity but is 30-fold less active against gram-negative bacteria. We determined the topological structure and lipid interactions of these two peptides in a lipopolysaccharide (LPS)-rich membrane that mimics the outer membrane of gram-negative bacteria and in the POPE/POPG membrane, which mimics the membrane of gram-positive bacteria. (31)P NMR line shapes indicate that both peptides cause less orientational disorder in the LPS-rich membrane than in the POPE/POPG membrane. (13)C chemical shifts and (13)C-(1)H dipolar couplings show that both peptides maintain their β-hairpin conformation in these membranes and are largely immobilized, but the mutant exhibits noticeable intermediate-time scale motion in the LPS membrane at physiological temperature, suggesting shallow insertion. Indeed, (1)H spin diffusion from lipid chains to the peptides shows that PG-1 fully inserts into the LPS-rich membrane whereas the mutant does not. The (13)C-(31)P distances between the most hydrophobically embedded Arg of PG-1 and the lipid (31)P are significantly longer in the LPS membrane than in the POPE/POPG membrane, indicating that PG-1 does not cause toroidal pore defects in the LPS membrane, in contrast to its behavior in the POPE/POPG membrane. Taken together, these data indicate that PG-1 causes transmembrane pores of the barrel-stave type in the LPS membrane, thus allowing further translocation of the peptide into the inner membrane of gram-negative bacteria to kill the cells. In comparison, the less cationic mutant cannot fully cross the LPS membrane because of weaker electrostatic attractions, thus causing weaker antimicrobial activities. Therefore, strong electrostatic attraction between the peptide and the membrane surface, ensured by having a sufficient number of Arg residues, is essential for potent antimicrobial activities against gram-negative bacteria. The data provide a rational basis for controlling gram selectivity of AMPs by adjusting the charge densities.
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Affiliation(s)
- Yongchao Su
- Department of Chemistry, Iowa State University, Ames, IA 50011
| | - Alan J. Waring
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA 92697-4560
| | - Piotr Ruchala
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095
| | - Mei Hong
- Department of Chemistry, Iowa State University, Ames, IA 50011
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18
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Saitô H, Ando I, Ramamoorthy A. Chemical shift tensor - the heart of NMR: Insights into biological aspects of proteins. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2010; 57:181-228. [PMID: 20633363 PMCID: PMC2905606 DOI: 10.1016/j.pnmrs.2010.04.005] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 04/26/2010] [Indexed: 05/19/2023]
Affiliation(s)
- Hazime Saitô
- Department of Life Science, Himeji Institute of Technology, University of Hyogo, Kamigori, Hyog, 678-1297, Japan
| | - Isao Ando
- Department of Chemistry and Materials Science, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-0033, Japan
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109-1055, USA
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19
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Su Y, DeGrado WF, Hong M. Orientation, dynamics, and lipid interaction of an antimicrobial arylamide investigated by 19F and 31P solid-state NMR spectroscopy. J Am Chem Soc 2010; 132:9197-205. [PMID: 20536141 PMCID: PMC2904348 DOI: 10.1021/ja103658h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A number of arylamides have been synthesized and found to exhibit potent antimicrobial activities against a broad spectrum of Gram-positive and Gram-negative bacteria while exhibiting low toxicity toward eukaryotic cells. These facially amphiphilic foldamers have a relatively rigid intramolecular hydrogen-bonded arylamide as a framework, which places trifluormethyl versus positively charged amino and guanidino groups along opposite faces of the elongated molecule, facilitating interactions with lipid membranes. To better understand the mechanism of action of these antimicrobial foldamers, we have investigated the lipid interaction, depth of insertion, orientation, and dynamics of an arylamide, PMX30016, using (31)P and (19)F solid-state NMR spectroscopy. Static (31)P NMR line shapes of lipid membranes with a range of compositions indicate that PMX30016 does not disrupt the lamellar order of the lipid bilayer but perturbs the lipid headgroup conformation. This headgroup perturbation, manifested as systematic (31)P chemical shift anisotropy increases, is consistent with the well documented "electrometer" effect of lipid membranes in response to the addition of positive charges to membrane surfaces. Paramagnetic relaxation enhancement experiments indicate that the arylamide inserts into the membrane-water interface, just below the headgroup region. Measurement of (19)F-(19)F dipolar couplings within each CF(3) moiety revealed that PMX30016 is oriented with the molecular plane 20 degrees and 30 degrees from the membrane normal of neutral and anionic bilayers, respectively, and the long molecular axis lies parallel to the membrane plane. Thus, this arylamide inserts into the bilayer in a knife-like fashion, consistent with previous vibrational spectroscopy results. Moreover, (19)F NMR line shapes indicate that this molecular knife undergoes fast uniaxial rotation around the bilayer normal. These results suggest that antimicrobial arylamides destabilize anionic lipid membranes primarily by altering the membrane electric potential profile, and the spinning molecular knife may additionally create transient defects in the lipid membrane. Compared to typical antimicrobial peptides, this arylamide has more subtle effects on and is less disruptive of the structure of lipid bilayers.
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Affiliation(s)
- Yongchao Su
- Department of Chemistry, Iowa State University, Ames, IA 50011
| | - William F. DeGrado
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104-6059
| | - Mei Hong
- Department of Chemistry, Iowa State University, Ames, IA 50011
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20
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Kim C. An NMR Study on the Phase Changes of Lipid Bilayers by Antimicrobial Peptides. JOURNAL OF THE KOREAN CHEMICAL SOCIETY-DAEHAN HWAHAK HOE JEE 2010. [DOI: 10.5012/jkcs.2010.54.02.183] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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21
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Kim C. An NMR Study on the Phase Change of Lipid Membranes by an Antimicrobial Peptide, Protegrin-1. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.02.372] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Agrawal P, Kiihne S, Hollander J, Hofmann M, Langosch D, de Groot H. A solid-state NMR study of changes in lipid phase induced by membrane-fusogenic LV-peptides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:202-9. [DOI: 10.1016/j.bbamem.2009.10.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 10/15/2009] [Accepted: 10/25/2009] [Indexed: 10/20/2022]
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23
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Zhang Y, Doherty T, Li J, Lu W, Barinka C, Lubkowski J, Hong M. Resonance assignment and three-dimensional structure determination of a human alpha-defensin, HNP-1, by solid-state NMR. J Mol Biol 2010; 397:408-22. [PMID: 20097206 DOI: 10.1016/j.jmb.2010.01.030] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 12/28/2009] [Accepted: 01/14/2010] [Indexed: 11/26/2022]
Abstract
Human alpha-defensins [human neutrophil peptides (HNPs)] are immune defense mini-proteins that act by disrupting microbial cell membranes. Elucidating the three-dimensional (3D) structures of HNPs in lipid membranes is important for understanding their mechanisms of action. Using solid-state NMR (SSNMR), we have determined the 3D structure of HNP-1 in a microcrystalline state outside the lipid membrane, which provides benchmarks for structure determination and comparison with the membrane-bound state. From a suite of two-dimensional and 3D magic-angle spinning experiments, (13)C and (15)N chemical shifts that yielded torsion angle constraints were obtained, while inter-residue distances were obtained to restrain the 3D fold. Together, these constraints led to the first high-resolution SSNMR structure of a human defensin. The SSNMR structure has close similarity to the crystal structures of the HNP family, with the exception of the loop region between the first and second beta-strands. The difference, which is partially validated by direct torsion angle measurements of selected loop residues, suggests possible conformational variation and flexibility of this segment of the protein, which may regulate HNP interaction with the phospholipid membrane of microbial cells.
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Affiliation(s)
- Yuan Zhang
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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24
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Lee J, Ham S, Im W. Beta-hairpin restraint potentials for calculations of potentials of mean force as a function of beta-hairpin tilt, rotation, and distance. J Comput Chem 2009; 30:1334-43. [PMID: 19009593 DOI: 10.1002/jcc.21154] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We have developed a set of restraint potentials for beta-hairpin tilt relative to the membrane normal, beta-hairpin rotation around the beta-hairpin axis, and hairpin-hairpin distance. Such restraint potentials enable us to characterize the molecular basis of specific beta-hairpin tilt and rotation in membranes and hairpin-hairpin interactions at the atomic level by sampling their conformational space along these degrees of freedom, i.e., reaction coordinates, during molecular dynamics simulations. We illustrate the efficacy of the beta-hairpin restraint potentials by calculating the potentials of mean force (PMFs) as a function of tilt and rotation angles of protegrin-1 (PG-1), a beta-hairpin antimicrobial peptide, in an implicit membrane model. The peptide association in the membrane is also examined by calculating the PMFs as a function of distance between two PG-1 peptides in various dimer interfaces. These novel restraint potentials are found to perform well in each of these cases and are expected to be a useful means to study the microscopic driving forces of insertion, tilting, and rotation of beta-hairpin peptides in membranes as well as their association in aqueous solvent or membrane environments particularly when combined with explicit solvent models.
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Affiliation(s)
- Jinhyuk Lee
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, 2030 Becker Drive, Lawrence, Kansas 66047, USA
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25
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Kim C, Spano J, Park EK, Wi S. Evidence of pores and thinned lipid bilayers induced in oriented lipid membranes interacting with the antimicrobial peptides, magainin-2 and aurein-3.3. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1482-96. [PMID: 19409370 DOI: 10.1016/j.bbamem.2009.04.017] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Revised: 04/22/2009] [Accepted: 04/22/2009] [Indexed: 11/29/2022]
Abstract
Dynamic structures of supramolecular lipid assemblies, such as toroidal pores and thinned bilayers induced in oriented lipid membranes, which are interacting with membrane-acting antimicrobial peptides (AMPs), magainin-2 and aurein-3.3, were explored by 31P and 2H solid-state NMR (ssNMR) spectroscopy. Various types of phospholipid systems, such as POPC-d31, POPC-d31/POPG, and POPC-d31/cholesterol, were investigated to understand the membrane disruption mechanisms of magainin-2 and aurein-3.3 peptides at various peptide-to-lipid (P:L) ratios. The experimental lineshapes of anisotropic 31P and 2H ssNMR spectra measured on these peptide-lipid systems were simulated reasonably well by assuming the presence of supramolecular lipid assemblies, such as toroidal pores and thinned bilayers, in membranes. Furthermore, the observed decrease in the anisotropic frequency span of either 31P or 2H ssNMR spectra of oriented lipid bilayers, particularly when anionic POPG lipids are interacting with AMPs at high P:L ratios, can directly be explained by a thinned membrane surface model with fast lateral diffusive motions of lipids. The spectral analysis protocol we developed enables extraction of the lateral diffusion coefficients of lipids distributed on the curved surfaces of pores and thinned bilayers on a few nanometers scale.
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Affiliation(s)
- Chul Kim
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA
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26
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Cheng JTJ, Hale JD, Elliot M, Hancock REW, Straus SK. Effect of membrane composition on antimicrobial peptides aurein 2.2 and 2.3 from Australian southern bell frogs. Biophys J 2009; 96:552-65. [PMID: 19167304 DOI: 10.1016/j.bpj.2008.10.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 10/09/2008] [Indexed: 12/25/2022] Open
Abstract
The effects of hydrophobic thickness and the molar phosphatidylglycerol (PG) content of lipid bilayers on the structure and membrane interaction of three cationic antimicrobial peptides were examined: aurein 2.2, aurein 2.3 (almost identical to aurein 2.2, except for a point mutation at residue 13), and a carboxy C-terminal analog of aurein 2.3. Circular dichroism results indicated that all three peptides adopt an alpha-helical structure in the presence of a 3:1 molar mixture of 1,2-dimyristoyl-sn-glycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPC/DMPG), and 1:1 and 3:1 molar mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPC/POPG). Oriented circular dichroism data for three different lipid compositions showed that all three peptides were surface-adsorbed at low peptide concentrations, but were inserted into the membrane at higher peptide concentrations. The (31)P solid-state NMR data of the three peptides in the DMPC/DMPG and POPC/POPG bilayers showed that all three peptides significantly perturbed lipid headgroups, in a peptide or lipid composition-dependent manner. Differential scanning calorimetry results demonstrated that both amidated aurein peptides perturbed the overall phase structure of DMPC/DMPG bilayers, but perturbed the POPC/POPG chains less. The nature of the perturbation of DMPC/DMPG bilayers was most likely micellization, and for the POPC/POPG bilayers, distorted toroidal pores or localized membrane aggregate formation. Calcein release assay results showed that aurein peptide-induced membrane leakage was more severe in DMPC/DMPG liposomes than in POPC/POPG liposomes, and that aurein 2.2 induced higher calcein release than aurein 2.3 and aurein 2.3-COOH from 1:1 and 3:1 POPC/POPG liposomes. Finally, DiSC(3)5 assay data further delineated aurein 2.2 from the others by showing that it perturbed the lipid membranes of intact S. aureus C622 most efficiently, whereas aurein 2.3 had the same efficiency as gramicidin S, and aurein 2.3-COOH was the least efficient. Taken together, these data show that the membrane interactions of aurein peptides are affected by the hydrophobic thickness of the lipid bilayers and the PG content.
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Affiliation(s)
- John T J Cheng
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
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27
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Tang M, Waring AJ, Hong M. Effects of arginine density on the membrane-bound structure of a cationic antimicrobial peptide from solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:514-21. [PMID: 19059201 DOI: 10.1016/j.bbamem.2008.10.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 10/02/2008] [Accepted: 10/30/2008] [Indexed: 11/30/2022]
Abstract
Solid-state NMR spectroscopy is used to determine the membrane-bound topological structure of a cationic beta-hairpin antimicrobial peptide in which the number of Arg residues has been halved. The parent peptide, PG-1, was previously found to form transmembrane beta-barrels in anionic membranes where the Arg residues complex with the lipid phosphate groups to cause toroidal pore defects in the membrane. In comparison, the charge-attenuated and less active mutant studied here forms beta-sheets that lie on the surface of the zwitterionic membrane and only partially insert into the anionic membrane. The mutant also exhibits much looser contact with the lipid headgroups. These results indicate that transmembrane insertion and tight Arg-phosphate association are two important elements for strong antimicrobial activities of this class of peptides. Comparison with other beta-hairpin antimicrobial peptides studied so far further suggests a relative potency scale for the various mechanisms of action for the beta-sheet family of antimicrobial peptides. The transmembrane insertion-toroidal pore mechanism is the most potent in disrupting the lipid bilayer, followed by the large-amplitude in-plane motional mechanism. The carpet model, where peptides aggregate on the membrane surface to cause lateral expansion and eventual micellization of the membrane, is a weaker mechanism of action.
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Affiliation(s)
- Ming Tang
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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28
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Wi S, Kim C. Pore structure, thinning effect, and lateral diffusive dynamics of oriented lipid membranes interacting with antimicrobial peptide protegrin-1: 31P and 2H solid-state NMR study. J Phys Chem B 2008; 112:11402-14. [PMID: 18700738 DOI: 10.1021/jp801825k] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Membrane pores that are induced in oriented membranes by an antimicrobial peptide (AMP), protegrin-1 (PG-1), are investigated by (31)P and (2)H solid state NMR spectroscopy. We incorporated a well-studied peptide, protegrin-1 (PG-1), a beta-sheet AMP, to investigate AMP-induced dynamic supramolecular lipid assemblies at different peptide concentrations and membrane compositions. Anisotropic NMR line shapes specifying toroidal pores and thinned membranes, which are formed in membrane bilayers by the binding of AMPs, have been analyzed for the first time. Theoretical NMR line shapes of lipids distributed on the surface of toroidal pores and thinned membranes reproduce reasonably well the line shape characteristics of our experimentally measured (31)P and (2)H solid-state NMR spectra of oriented lipids binding with PG-1. The lateral diffusions of lipids are also analyzed from the motionally averaged one- and two-dimensional (31)P and (2)H solid-state NMR spectra of oriented lipids that are binding with AMPs.
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Affiliation(s)
- Sungsool Wi
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA.
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29
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Fuhrman CA, Warren AD, Waring AJ, Dutz SM, Sharma S, Lehrer RI, Cole AL, Cole AM. Retrocyclin RC-101 overcomes cationic mutations on the heptad repeat 2 region of HIV-1 gp41. FEBS J 2007; 274:6477-87. [PMID: 18028423 DOI: 10.1111/j.1742-4658.2007.06165.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Retrocyclin RC-101, a theta-defensin with lectin-like properties, potently inhibits infection by many HIV-1 subtypes by binding to the heptad repeat 2 (HR2) region of glycoprotein 41 (gp41) and preventing six-helix bundle formation. In the present study, we used in silico computational exploration to identify residues of HR2 that interacted with RC-101, and then analyzed the HIV-1 sequence database at Los Alamos National Laboratory (New Mexico, USA) for residue variations in the heptad repeat 1 (HR1) and HR2 segments that could plausibly impart in vivo resistance. Docking RC-101 to gp41 peptides in silico confirmed its strong preference for HR2 over HR1, and implicated residues crucial for its ability to bind HR2. We mutagenized these residues in pseudotyped HIV-1 JR.FL reporter viruses, and subjected them to single-round replication assays in the presence of 1.25-10 microg x mL(-1) RC-101. Apart from one mutant that was partially resistant to RC-101, the other pseudotyped viruses with single-site cationic mutations in HR2 manifested absent or impaired infectivity or retained wild-type susceptibility to RC-101. Overall, these data suggest that most mutations capable of rendering HIV-1 resistant to RC-101 will also exert deleterious effects on the ability of HIV-1 to initiate infections - an interesting and novel property for a potential topical microbicide.
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Affiliation(s)
- Christopher A Fuhrman
- Molecular Biology & Microbiology, Biomolecular Science Center, Burnett College of Biomedical Sciences at University of Central Florida, Orlando, FL 32816, USA
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30
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Marulanda D, Tasayco ML, Cataldi M, Arriaran V, Polenova T. Resonance assignments and secondary structure analysis of E. coli thioredoxin by magic angle spinning solid-state NMR spectroscopy. J Phys Chem B 2007; 109:18135-45. [PMID: 16853329 DOI: 10.1021/jp052774d] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
De novo site-specific 13C and 15N backbone and sidechain resonance assignments are presented for uniformly enriched E. coli thioredoxin, established using two-dimensional homo- and heteronuclear solid-state magic angle spinning NMR correlation spectroscopy. Backbone dihedral angles and secondary structure were derived from the statistical analysis of the secondary chemical shifts, and are in good agreement with solution values for the intact full-length thioredoxin, with the exception of a small number of residues located at the termini of the individual secondary structure elements. A large number of cross-peaks observed in the DARR spectra with long mixing times correspond to the pairs of carbon atoms separated by 4-6 angstroms, suggesting that DARR could be efficiently employed for observation of medium- and long-range correlations. The 108 amino acid residue E. coli thioredoxin is the largest uniformly enriched protein assigned to this degree of completeness by solid-state NMR spectroscopy to date. It is anticipated that with a combination of two-dimensional correlation experiments and high magnetic fields, resonance assignments and secondary structure can be generally derived for other noncrystalline proteins.
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Affiliation(s)
- Dabeiba Marulanda
- Department of Chemistry and Biochemistry, Brown Laboratories, University of Delaware, Newark, Delaware 19716, USA
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31
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Mason AJ, Marquette A, Bechinger B. Zwitterionic phospholipids and sterols modulate antimicrobial peptide-induced membrane destabilization. Biophys J 2007; 93:4289-99. [PMID: 17766347 PMCID: PMC2098721 DOI: 10.1529/biophysj.107.116681] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cationic amphipathic alpha-helical peptides preferentially disrupt anionic lipids in mixed model membranes, potentially causing a catastrophic release of the cell contents or attenuation of the membrane potential. The effective role of such peptides requires considerable discrimination between target and host cells, which is likely to occur at the level of the cell membrane. Here, we explore the roles of a variety of common membrane constituents in mediating the interaction between the antimicrobial peptide pleurocidin and model membranes. We employ intrinsic tryptophan fluorescence and circular dichroism to observe the effect of increasing concentrations of sterol in the membrane on peptide binding, using (2)H solid-state NMR of chain deuterated lipids simultaneously to probe the effective chain disruption of the anionic phospholipid component of the membrane. We show that the degree of ordering of the lipid acyl chains in the membrane is dependent on the nature of the zwitterionic phospholipid headgroup in mixed anionic membranes. Furthermore, the presence of cholesterol and ergosterol increases acyl chain order in the liquid crystalline model membranes, but to differing degrees. Our results show how sterols can protect even negatively charged membranes from the disruptive effects of antimicrobial peptides, thereby providing a molecular view of the differences in sensitivity of various target membranes to linear cationic antibiotic peptides where bacteria (no sterols) are most susceptible, lower eukaryotes including fungi (containing ergosterol) exhibit an intermediate degree of sensitivity, and higher organisms (containing cholesterol) are largely resistant to antimicrobial peptides.
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Affiliation(s)
- A James Mason
- Faculté de chimie, Université Louis Pasteur/Centre National de la Recherche Scientifique UMR 7177, Institut le Bel, Strasbourg, France.
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32
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Tang M, Waring AJ, Hong M. Phosphate-Mediated Arginine Insertion into Lipid Membranes and Pore Formation by a Cationic Membrane Peptide from Solid-State NMR. J Am Chem Soc 2007; 129:11438-46. [PMID: 17705480 DOI: 10.1021/ja072511s] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The insertion of charged amino acid residues into the hydrophobic part of lipid bilayers is energetically unfavorable yet found in many cationic membrane peptides and protein domains. To understand the mechanism of this translocation, we measured the (13)C-(31)P distances for an Arg-rich beta-hairpin antimicrobial peptide, PG-1, in the lipid membrane using solid-state NMR. Four residues, including two Arg's, scattered through the peptide were chosen for the distance measurements. Surprisingly, all residues show short distances to the lipid (31)P: 4.0-6.5 A in anionic POPE/POPG membranes and 6.5-8.0 A in zwitterionic POPC membranes. The shortest distance of 4.0 A, found for a guanidinium Czeta at the beta-turn, suggests N-H...O-P hydrogen bond formation. Torsion angle measurements of the two Arg's quantitatively confirm that the peptide adopts a beta-hairpin conformation in the lipid bilayer, and gel-phase 1H spin diffusion from water to the peptide indicates that PG-1 remains transmembrane in the gel phase of the membrane. For this transmembrane beta-hairpin peptide to have short (13)C-(31)P distances for multiple residues in the molecule, some phosphate groups must be embedded in the hydrophobic part of the membrane, with the local (31)P plane parallel to the beta-strand. This provides direct evidence for toroidal pores, where some lipid molecules change their orientation to merge the two monolayers. We propose that the driving force for this toroidal pore formation is guanidinium-phosphate complexation, where the cationic Arg residues drag the anionic phosphate groups along as they insert into the hydrophobic part of the membrane. This phosphate-mediated translocation of guanidinium ions may underlie the activity of other Arg-rich antimocrobial peptides and may be common among cationic membrane proteins.
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Affiliation(s)
- Ming Tang
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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33
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Agrawal P, Kiihne S, Hollander J, Hulsbergen F, Hofmann M, Langosch D, de Groot H. Solid state NMR investigation of the interaction between biomimetic lipid bilayers and de novo designed fusogenic peptides. Chembiochem 2007; 8:493-6. [PMID: 17328022 DOI: 10.1002/cbic.200600518] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Prashant Agrawal
- Biophysical Organic Chemistry/Solid State NMR, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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34
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Cady SD, Goodman C, Tatko CD, DeGrado WF, Hong M. Determining the orientation of uniaxially rotating membrane proteins using unoriented samples: a 2H, 13C, AND 15N solid-state NMR investigation of the dynamics and orientation of a transmembrane helical bundle. J Am Chem Soc 2007; 129:5719-29. [PMID: 17417850 DOI: 10.1021/ja070305e] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Membrane protein orientation has traditionally been determined by NMR using mechanically or magnetically aligned samples. Here we show a new NMR approach that abolishes the need for preparing macroscopically aligned membranes. When the protein undergoes fast uniaxial rotation around the bilayer normal, the 0 degrees -frequency of the motionally averaged powder spectrum is identical to the frequency of the aligned protein whose alignment axis is along the magnetic field. Thus, one can use unoriented membranes to determine the orientation of the protein relative to the bilayer normal. We demonstrate this approach on the M2 transmembrane peptide (M2TMP) of influenza A virus, which is known to assemble into a proton-conducting tetrameric helical bundle. The fast uniaxial rotational diffusion of the M2TMP helical bundle around the membrane normal is characterized via 2H quadrupolar couplings, C-H and N-H dipolar couplings, 13C chemical shift anisotropies, and 1H T1rho relaxation times. We then show that 15N chemical shift anisotropy and N-H dipolar coupling measured on these powder samples can be analyzed to yield precise tilt angles and rotation angles of the helices. The data show that the tilt angle of the M2TMP helices depends on the membrane thickness to reduce the hydrophobic mismatch. Moreover, the orientation of a longer M2 peptide containing both the transmembrane domain and cytoplasmic residues is similar to the orientation of the transmembrane domain alone, suggesting that the transmembrane domain regulates the orientation of this protein and that structural information obtained from M2TMP may be extrapolated to the longer peptide. This powder-NMR approach for orientation determination is generally applicable and can be extended to larger membrane proteins.
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Affiliation(s)
- Sarah D Cady
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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35
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Hong M, Doherty T. Orientation Determination of Membrane-Disruptive Proteins Using Powder Samples and Rotational Diffusion: A Simple Solid-State NMR Approach. Chem Phys Lett 2006; 432:296-300. [PMID: 17364006 PMCID: PMC1826912 DOI: 10.1016/j.cplett.2006.10.067] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The orientation of membrane proteins undergoing fast uniaxial rotation around the bilayer normal can be determined without macroscopic alignment. We show that the motionally averaged powder spectra exhibit their 0° frequency, [Formula: see text], at the same position as the peak of an aligned sample with the alignment axis parallel to the magnetic field. This equivalence is exploited to determine the orientation of a β-sheet antimicrobial peptide not amenable to macroscopic alignment, using (13)CO and (15)N chemical shifts from powder spectra. This powder sample approach permits orientation determination of naturally membrane-disruptive proteins in diverse environments and under magic-angle spinning.
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Affiliation(s)
- Mei Hong
- Department of Chemistry, Iowa State University, Ames, IA 50011
| | - Tim Doherty
- Department of Chemistry, Iowa State University, Ames, IA 50011
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36
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Toke O, Cegelski L, Schaefer J. Peptide antibiotics in action: Investigation of polypeptide chains in insoluble environments by rotational-echo double resonance. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1314-29. [PMID: 16616889 DOI: 10.1016/j.bbamem.2006.02.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 02/16/2006] [Accepted: 02/28/2006] [Indexed: 11/22/2022]
Abstract
Rotational-echo double resonance (REDOR) is a solid-state NMR technique that has the capability of providing intra- and intermolecular distance and orientational restraints in non-crystallizable, poorly soluble heterogeneous molecular systems such as cell membranes and cell walls. In this review, we will present two applications of REDOR: the investigation of a magainin-related antimicrobial peptide in lipid bilayers and the study of a vancomycin-like glycopeptide in the cell walls of Staphylococcus aureus.
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Affiliation(s)
- Orsolya Toke
- Institute for Structural Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary
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37
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Wang W, Mulakala C, Ward SC, Jung G, Luong H, Pham D, Waring AJ, Kaznessis Y, Lu W, Bradley KA, Lehrer RI. Retrocyclins kill bacilli and germinating spores of Bacillus anthracis and inactivate anthrax lethal toxin. J Biol Chem 2006; 281:32755-64. [PMID: 16790431 PMCID: PMC2440672 DOI: 10.1074/jbc.m603614200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Theta-defensins are cyclic octadecapeptides encoded by the modified alpha-defensin genes of certain nonhuman primates. The recent demonstration that human alpha-defensins could prevent deleterious effects of anthrax lethal toxin in vitro and in vivo led us to examine the effects of theta-defensins on Bacillus anthracis (Sterne). We tested rhesus theta-defensins 1-3, retrocyclins 1-3, and several analogues of RC-1. Low concentrations of theta-defensins not only killed vegetative cells of B. anthracis (Sterne) and rendered their germinating spores nonviable, they also inactivated the enzymatic activity of anthrax lethal factor and protected murine RAW-264.7 cells from lethal toxin, a mixture of lethal factor and protective antigen. Structure-function studies indicated that the cyclic backbone, intramolecular tri-disulfide ladder, and arginine residues of theta-defensins contributed substantially to these protective effects. Surface plasmon resonance studies showed that retrocyclins bound the lethal factor rapidly and with high affinity. Retrocyclin-mediated inhibition of the enzymatic activity of lethal factor increased substantially if the enzyme and peptide were preincubated before substrate was added. The temporal discrepancy between the rapidity of binding and the slowly progressive extent of lethal factor inhibition suggest that post-binding events, perhaps in situ oligomerization, contribute to the antitoxic properties of retrocyclins. Overall, these findings suggest that theta-defensins provide molecular templates that could be used to create novel agents effective against B. anthracis and its toxins.
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Affiliation(s)
- Wei Wang
- Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095
| | - Chandrika Mulakala
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455
| | - Sabrina C. Ward
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, UCLA, Los Angeles, California 90095
| | - Grace Jung
- Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095
| | - Hai Luong
- Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095
| | - Duy Pham
- Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095
| | - Alan J. Waring
- Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095
| | - Yiannis Kaznessis
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455
| | - Wuyuan Lu
- Institute for Human Virology, Biotechnology Institute, University of Maryland, Baltimore, Maryland 21201
| | - Kenneth A. Bradley
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455
| | - Robert I. Lehrer
- Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095
- To whom correspondence should be addressed: Dept. of Medicine, David Geffen School of Medicine, UCLA, 10833 LeConte Ave., Los Angeles, CA 90095. Tel.: 310-825-0133; Fax: 310-206-8766; E-mail:
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38
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Doherty T, Waring AJ, Hong M. Peptide-lipid interactions of the beta-hairpin antimicrobial peptide tachyplesin and its linear derivatives from solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1285-91. [PMID: 16678119 DOI: 10.1016/j.bbamem.2006.03.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 03/13/2006] [Accepted: 03/14/2006] [Indexed: 10/24/2022]
Abstract
The peptide-lipid interaction of a beta-hairpin antimicrobial peptide tachyplesin-1 (TP-1) and its linear derivatives are investigated to gain insight into the mechanism of antimicrobial activity. (31)P and (2)H NMR spectra of uniaxially aligned lipid bilayers of varying compositions and peptide concentrations are measured to determine the peptide-induced orientational disorder and the selectivity of membrane disruption by tachyplesin. The disulfide-linked TP-1 does not cause any disorder to the neutral POPC and POPC/cholesterol membranes but induces both micellization and random orientation distribution to the anionic POPE/POPG membranes above a peptide concentration of 2%. In comparison, the anionic POPC/POPG bilayer is completely unaffected by TP-1 binding, suggesting that TP-1 induces negative curvature strain to the membrane as a mechanism of its action. Removal of the disulfide bonds by substitution of Cys residues with Tyr and Ala abolishes the micellization of POPE/POPG bilayers but retains the orientation randomization of both POPC/POPG and POPE/POPG bilayers. Thus, linear tachyplesin derivatives have membrane disruptive abilities but use different mechanisms from the wild-type peptide. The different lipid-peptide interactions between TP-1 and other beta-hairpin antimicrobial peptides are discussed in terms of their molecular structure.
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Affiliation(s)
- Timothy Doherty
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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Ramamoorthy A, Thennarasu S, Tan A, Lee DK, Clayberger C, Krensky AM. Cell selectivity correlates with membrane-specific interactions: a case study on the antimicrobial peptide G15 derived from granulysin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:154-63. [PMID: 16579960 DOI: 10.1016/j.bbamem.2006.02.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2005] [Revised: 02/08/2006] [Accepted: 02/13/2006] [Indexed: 11/18/2022]
Abstract
A 15-residue peptide dimer G15 derived from the cell lytic protein granulysin has been shown to exert potent activity against microbes, including E. coli, but not against human Jurkat cells [Z. Wang, E. Choice, A. Kaspar, D. Hanson, S. Okada, S.C. Lyu, A.M. Krensky, C. Clayberger, Bactericidal and tumoricidal activities of synthetic peptides derived from granulysin. J. Immunol. 165 (2000) 1486-1490]. We investigated the target membrane selectivity of G15 using fluorescence, circular dichroism and 31P NMR methods. The ANS uptake assay shows that the extent of E. coli outer membrane disruption depends on G15 concentration. 31P NMR spectra obtained from E. coli total lipid bilayers incorporated with G15 show disruption of lipid bilayers. Fluorescence binding studies on the interaction of G15 with synthetic liposomes formed of E. coli lipids suggest a tight binding of the peptide at the membrane interface. The peptide also binds to negatively charged POPC/POPG (3:1) lipid vesicles but fails to insert deep into the membrane interior. These results are supported by the peptide-induced changes in the measured isotropic chemical shift and T1 values of POPG in 3:1 POPC:POPG multilamellar vesicles while neither a non-lamellar phase nor a fragmentation of bilayers was observed from NMR studies. The circular dichroism studies reveal that the peptide exists as a random coil in solution but folds into a less ordered conformation upon binding to POPC/POPG (3:1) vesicles. However, G15 does not bind to lipid vesicles made of POPC/POPG/Chl (9:1:1) mixture, mimicking tumor cell membrane. These results explain the susceptibility of E. coli and the resistance of human Jurkat cells to G15, and may have implications in designing membrane-selective therapeutic agents.
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Affiliation(s)
- Ayyalusamy Ramamoorthy
- Department of Chemistry and Biophysics Research Division, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109-1055, USA.
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40
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Mode of action of the new antibiotic for Gram-positive pathogens daptomycin: comparison with cationic antimicrobial peptides and lipopeptides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1215-23. [PMID: 16615993 DOI: 10.1016/j.bbamem.2006.02.009] [Citation(s) in RCA: 312] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 02/01/2006] [Accepted: 02/02/2006] [Indexed: 11/26/2022]
Abstract
With the steady rise in the number of antibiotic-resistant Gram-positive pathogens, it has become increasingly important to find new antibacterial agents which are highly active and have novel and diversified mechanisms of action. Two classes will be discussed here: the cationic antimicrobial peptides, which are amphiphilic in nature, targeting membranes and increasing their permeability; and lipopeptides, which consist of linear or cyclic peptides with an N-terminus that is acylated with a fatty acid side chain. One member of the cyclic lipopeptide family, the anionic molecule daptomycin, has been extensively studied and is the major focus of this review. Models will be presented on its mode of action and comparisons will be made to the known modes of action of cationic antimicrobial peptides and other lipopeptides.
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41
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Hong M. Solid-state NMR studies of the structure, dynamics, and assembly of beta-sheet membrane peptides and alpha-helical membrane proteins with antibiotic activities. Acc Chem Res 2006; 39:176-83. [PMID: 16548506 DOI: 10.1021/ar040037e] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
beta-Sheet antimicrobial peptides and alpha-helical channel-forming colicins are bactericidal molecules that target the lipid membranes of sensitive cells. Understanding the mechanisms of action of these proteins requires knowledge of their three-dimensional structure in the lipid bilayer. Solid-state NMR has been used to determine the conformation, orientation, depth of insertion, oligomerization, mobility, and lipid interaction of these membrane peptides and proteins. We review the NMR methods developed and applied to study the structure and dynamics of these antibiotic membrane proteins. These studies shed light on how these peptides disrupt lipid membranes and provide fundamental insights into the folding of beta-sheet and alpha-helical membrane proteins.
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Affiliation(s)
- Mei Hong
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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42
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Lu JX, Blazyk J, Lorigan GA. Exploring membrane selectivity of the antimicrobial peptide KIGAKI using solid-state NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1303-13. [PMID: 16537078 DOI: 10.1016/j.bbamem.2006.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 02/01/2006] [Accepted: 02/02/2006] [Indexed: 11/25/2022]
Abstract
The designed antimicrobial peptide KIGAKIKIGAKIKIGAKI possesses enhanced membrane selectivity for bacterial lipids, such as phosphatidylethanolamine and phosphatidylglycerol. The perturbation of the bilayer by the peptide was first monitored using oriented bilayer samples on glass plates. The alignment of POPE/POPG model membranes with respect to the bilayer normal was severely altered at 4 mol% KIGAKI while the alignment of POPC bilayers was retained. The interaction mechanism between the peptide and POPE/POPG bilayers was investigated by carefully comparing three bilayer MLV samples (POPE bilayers, POPG bilayers, and POPE/POPG 4/1 bilayers). KIGAKI induces the formation of an isotropic phase for POPE/POPG bilayers, but only a slight change in the (31)P NMR CSA line shape for both POPE and POPG bilayers, indicating the synergistic roles of POPE and POPG lipids in the disruption of the membrane structure by KIGAKI. (2)H NMR powder spectra show no reduction of the lipid chain order for both POPG and POPE/POPG bilayers upon peptide incorporation, supporting the evidence that the peptide acts as a surface peptide. (31)P longitudinal relaxation studies confirmed that different dynamic changes occurred upon interaction of the peptide with the three different lipid bilayers, indicating that the strong electrostatic interaction between the cationic peptide KIGAKI and anionic POPG lipids is not the only factor in determining the antimicrobial activity. Furthermore, (31)P and (2)H NMR powder spectra demonstrated a change in membrane characteristics upon mixing of POPE and POPG lipids. The interaction between different lipids, such as POPE and POPG, in the mixed bilayers may provide the molecular basis for the KIGAKI carpet mechanism in the permeation of the membrane.
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Affiliation(s)
- Jun-xia Lu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
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43
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Tang M, Waring AJ, Lehrer RI, Hong M. Orientation of a beta-hairpin antimicrobial peptide in lipid bilayers from two-dimensional dipolar chemical-shift correlation NMR. Biophys J 2006; 90:3616-24. [PMID: 16500957 PMCID: PMC1440742 DOI: 10.1529/biophysj.105.062075] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The orientation of a beta-sheet membrane peptide in lipid bilayers is determined, for the first time, using two-dimensional (2D) (15)N solid-state NMR. Retrocyclin-2 is a disulfide-stabilized cyclic beta-hairpin peptide with antibacterial and antiviral activities. We used 2D separated local field spectroscopy correlating (15)N-(1)H dipolar coupling with (15)N chemical shift to determine the orientation of multiply (15)N-labeled retrocyclin-2 in uniaxially aligned phosphocholine bilayers. Calculated 2D spectra exhibit characteristic resonance patterns that are sensitive to both the tilt of the beta-strand axis and the rotation of the beta-sheet plane from the bilayer normal and that yield resonance assignment without the need for singly labeled samples. Retrocyclin-2 adopts a transmembrane orientation in dilauroylphosphatidylcholine bilayers, with the strand axis tilted at 20 degrees +/- 10 degrees from the bilayer normal, but changes to a more in-plane orientation in thicker 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC) bilayers with a tilt angle of 65 degrees +/- 15 degrees . These indicate that hydrophobic mismatch regulates the peptide orientation. The 2D spectra are sensitive not only to the peptide orientation but also to its backbone (phi, psi) angles. Neither a bent hairpin conformation, which is populated in solution, nor an ideal beta-hairpin with uniform (phi, psi) angles and coplanar strands, agrees with the experimental spectrum. Thus, membrane binding orders the retrocyclin conformation by reducing the beta-sheet curvature but does not make it ideal. (31)P NMR spectra of lipid bilayers with different compositions indicate that retrocyclin-2 selectively disrupts the orientational order of anionic membranes while leaving zwitteronic membranes intact. These structural results provide insights into the mechanism of action of this beta-hairpin antimicrobial peptide.
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Affiliation(s)
- Ming Tang
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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Marcotte I, Bélanger A, Auger M. The orientation effect of gramicidin A on bicelles and Eu3+-doped bicelles as studied by solid-state NMR and FT-IR spectroscopy. Chem Phys Lipids 2006; 139:137-49. [PMID: 16413519 DOI: 10.1016/j.chemphyslip.2005.12.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Revised: 12/06/2005] [Accepted: 12/08/2005] [Indexed: 10/25/2022]
Abstract
We have explored the effect of gramicidin A (gA) on bicelle (Bic) orientation in the absence and presence of Eu(3+) by (31)P and (2)H NMR at different DMPC/gA ratios. FT-IR spectroscopy was used to assess the lipid chain ordering and verify the transmembrane peptide conformation. Our results show a time-dependent flipping of the bilayer normal alignment at high temperatures and high proportion of gA. The results are explained by both the diamagnetic susceptibility anisotropy of the beta(6.3) helical peptides and viscosity of the lipid mixture. The concentration effect of gramicidin on Bic/Eu(3+) is compared to that on Eu(3+)-doped DMPC liposomes. The Bic/Eu(3+) system is no longer oriented in the presence of gA and adopts a vesicular morphology while the peptide incorporation induces the formation of ellipsoidal DMPC/Eu(3+) assemblies aligned with their normal parallel to the magnetic field. The difference is explained in terms of lipid chain disorder and size of the bilayers.
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Affiliation(s)
- Isabelle Marcotte
- Département de Chimie, Centre de Recherche en Sciences et Ingénierie des Macromolécules, Université Laval, Québec, Qué., Canada G1K 7P4
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45
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Mason AJ, Martinez A, Glaubitz C, Danos O, Kichler A, Bechinger B. The antibiotic and DNA-transfecting peptide LAH4 selectively associates with, and disorders, anionic lipids in mixed membranes. FASEB J 2005; 20:320-2. [PMID: 16352649 DOI: 10.1096/fj.05-4293fje] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The histidine-rich amphipathic peptide LAH4 has antibiotic and DNA delivery capabilities. The peptide has a strong affinity for anionic lipids found in the outer membrane of bacterial membranes. A role for anionic lipids in release of cationic plasmid-containing complexes has been proposed previously, and disruption of membrane asymmetry and presentation of phosphatidylserine (PS) in the membrane outer leaflet is a general feature observed in diseased mammalian cells. Therefore, to understand the peptide-lipid interactions in more detail, solid-state NMR experiments on model membranes have been performed. 31P MAS NMR on mixed phosphatidylcholine (PC)/PS and PC/phosphatidylglycerol (PG) membranes has been used to demonstrate a strong interaction between LAH4 and anionic lipids. By using deuterated lipids and wide-line 2H NMR when probing lipid chain order, it is demonstrated that LAH4 preferentially interacts with PS over PC and effectively disorders the anionic PS lipid fatty acyl chains. In addition, we demonstrate that the efficiency of gene transfer in vitro to different cell lines is closely related to the degree of disruption of PS acyl chains for four isomers of LAH4. This work suggests a mechanism of selective destabilization by LAH4 of anionic lipids in the membranes of cells during transfection with implications for nucleic acid delivery in vivo.
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Affiliation(s)
- A James Mason
- Faculté de chimie, University Louis Pasteur/CNRS UMR717-LC3, Institut le Bel, Strasbourg, France.
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46
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Mani R, Waring AJ, Lehrer RI, Hong M. Membrane-disruptive abilities of beta-hairpin antimicrobial peptides correlate with conformation and activity: a 31P and 1H NMR study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1716:11-8. [PMID: 16182236 DOI: 10.1016/j.bbamem.2005.08.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Revised: 08/08/2005] [Accepted: 08/23/2005] [Indexed: 11/28/2022]
Abstract
The membrane interaction and solution conformation of two mutants of the beta-hairpin antimicrobial peptide, protegrin-1 (PG-1), are investigated to understand the structural determinants of antimicrobial potency. One mutant, [A(6,8,13,15)] PG-1, does not have the two disulfide bonds in wild-type PG-1, while the other, [Delta(4,18) G10] PG-1, has only half the number of cationic residues. 31P solid-state NMR lineshapes of uniaxially aligned membranes indicate that the membrane disorder induced by the three peptides decreases in the order of PG-1 > [Delta(4,18) G10] PG-1>>[A(6,8,13,15)] PG-1. Solution NMR studies of the two mutant peptides indicate that [Delta(4,18) G10] PG-1 preserves the beta-hairpin fold of the wild-type peptide while [A(6,8,13,15)] PG-1 adopts a random coil conformation. These NMR results correlate well with the known activities of these peptides. Thus, for this class of peptides, the presence of a beta-hairpin fold is more essential than the number of cationic charges for antimicrobial activity. This study indicates that 31P NMR lineshapes of uniaxially aligned membranes are well correlated with antimicrobial activity, and can be used as a diagnostic tool to understand the peptide-lipid interactions of these antimicrobial peptides.
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Affiliation(s)
- Rajeswari Mani
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
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47
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Dave PC, Billington E, Pan YL, Straus SK. Interaction of alamethicin with ether-linked phospholipid bilayers: oriented circular dichroism, 31P solid-state NMR, and differential scanning calorimetry studies. Biophys J 2005; 89:2434-42. [PMID: 16055546 PMCID: PMC1366743 DOI: 10.1529/biophysj.105.067678] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2005] [Accepted: 07/18/2005] [Indexed: 11/18/2022] Open
Abstract
The arrangement of the antimicrobial peptide alamethicin was studied by oriented circular dichroism, 31P solid-state NMR, and differential scanning calorimetry in ether-linked phospholipid bilayers composed of 1,2-O-dihexadecyl-sn-glycero-3-phosphocholine (DHPC). The measurements were performed as a function of alamethicin concentration relative to the lipid concentration, and results were compared to those reported in the literature for ester-linked phospholipid bilayers. At ambient temperature, alamethicin incorporates into the hydrophobic core of DHPC bilayers but results in more lipid disorder than observed for ester-linked 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) lipid bilayers. This orientational disorder appears to depend on lipid properties such as bilayer thickness. Moreover, the results suggest that alamethicin inserts into the hydrophobic core of the bilayers (at high peptide concentration) for both ether- and ester-linked lipids but using a different mechanism, namely toroidal for DHPC and barrel-stave for POPC.
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Affiliation(s)
- Paresh C Dave
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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48
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Abstract
Defensins are peptidic components of the innate immune system of plants and animals. In mammals, defensins have evolved to have a central function in the host defense properties of granulocytic leukocytes, mucosal surfaces, skin and other epithelia. This review focuses on the biological functions of three structural subgroups of mammalian defensins and the evidence for their involvement as effectors of antimicrobial innate immunity.
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49
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Brogden KA. Antimicrobial peptides: pore formers or metabolic inhibitors in bacteria? Nat Rev Microbiol 2005; 3:238-50. [PMID: 15703760 DOI: 10.1038/nrmicro1098] [Citation(s) in RCA: 4001] [Impact Index Per Article: 210.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Antimicrobial peptides are an abundant and diverse group of molecules that are produced by many tissues and cell types in a variety of invertebrate, plant and animal species. Their amino acid composition, amphipathicity, cationic charge and size allow them to attach to and insert into membrane bilayers to form pores by 'barrel-stave', 'carpet' or 'toroidal-pore' mechanisms. Although these models are helpful for defining mechanisms of antimicrobial peptide activity, their relevance to how peptides damage and kill microorganisms still need to be clarified. Recently, there has been speculation that transmembrane pore formation is not the only mechanism of microbial killing. In fact several observations suggest that translocated peptides can alter cytoplasmic membrane septum formation, inhibit cell-wall synthesis, inhibit nucleic-acid synthesis, inhibit protein synthesis or inhibit enzymatic activity. In this review the different models of antimicrobial-peptide-induced pore formation and cell killing are presented.
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Affiliation(s)
- Kim A Brogden
- Department of Periodontics and Dows Institute for Dental Research, College of Dentistry, The University of Iowa, Iowa City, Iowa 52242, USA.
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