The Experts below are selected from a list of 1905 Experts worldwide ranked by ideXlab platform
Katsumi Matsuzaki - One of the best experts on this subject based on the ideXlab platform.
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Interaction of antimicrobial peptide Magainin 2 with gangliosides as a target for human cell binding.
Biochemistry, 2012Co-Authors: Yu Miyazaki, Megumi Aoki, Yoshiaki Yano, Katsumi MatsuzakiAbstract:Understanding how antimicrobial peptides (AMPs) interact with human cells is important to the development of antimicrobial agents as well as anticancer drugs. However, little is known about the mechanisms by which AMPs bind to cells and exert cytotoxicity. Negatively charged gangliosides on the cell surface are a potential target for cell binding. In this study, we investigated the interaction of F5W-Magainin 2 (MG) with gangliosides in detail. MG was colocalized with gangliosides on HeLa cells, indicating that gangliosides act as a receptor for MG. MG also bound to gangliosides in model membranes. The affinity increased with the number of negatively charged sialic acid residues. Physicochemical studies revealed that MG interacts with the monosialoganglioside GM1 differently from the typical bacterial anionic phospholipid phosphatidylglycerol. MG bound to GM1 more strongly than to phosphatidylglycerol, and the binding isotherm for GM1 could be analyzed by the Langmuir equation assuming charge neutralizati...
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Magainin 2 in Action: Distinct Modes of Membrane Permeabilization in Living Bacterial and Mammalian Cells
Biophysical journal, 2008Co-Authors: Yuichi Imura, Naoki Choda, Katsumi MatsuzakiAbstract:Interactions of cationic antimicrobial peptides with living bacterial and mammalian cells are little understood, although model membranes have been used extensively to elucidate how peptides permeabilize membranes. In this study, the interaction of F5W-Magainin 2 (GIGKWLHSAKKFGKAFVGEIMNS), an equipotent analogue of Magainin 2 isolated from the African clawed frog Xenopus laevis, with unfixed Bacillus megaterium and Chinese hamster ovary (CHO)-K1 cells was investigated, using confocal laser scanning microscopy. A small amount of tetramethylrhodamine-labeled F5W-Magainin 2 was incorporated into the unlabeled peptide for imaging. The influx of fluorescent markers of various sizes into the cytosol revealed that Magainin 2 permeabilized bacterial and mammalian membranes in significantly different ways. The peptide formed pores with a diameter of approximately 2.8 nm ( 23 nm) into the cytosol, accompanied by membrane budding and lipid flip-flop, mainly accumulating in mitochondria and nuclei. Adenosine triphosphate and negatively charged glycosaminoglycans were little involved in the Magainin-induced permeabilization of membranes in CHO-K1 cells. Furthermore, the susceptibility of CHO-K1 cells to Magainin was found to be similar to that of erythrocytes. Thus, the distinct membrane-permeabilizing processes of Magainin 2 in bacterial and mammalian cells were, to the best of our knowledge, visualized and characterized in detail for the first time.
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Action mechanism of PEGylated Magainin 2 analogue peptide
Biochimica et biophysica acta, 2007Co-Authors: Yuichi Imura, Minoru Nishida, Katsumi MatsuzakiAbstract:Abstract PEGylation is frequently used to improve the efficacy of protein and peptide drugs. Recently, we investigated its effects on the action mechanism of the cyclic β-sheet antimicrobial peptide tachyplesin I isolated from Tachypleus tridentatus [Y. Imura, M. Nishida, Y. Ogawa, Y. Takakura, K. Matsuzaki, Action Mechanism of Tachyplesin I and Effects of PEGylation, Biochim. Biophys. Acta 1768 (2007) 1160–1169]. PEGylation did not change the basic mechanism behind the membrane-permeabilizing effect of the peptide on liposomes, however, it decreased the antimicrobial activity and cytotoxicity. To obtain further information on the effects of PEGylation on the activities of antimicrobial peptides, we designed another structurally different PEGylated antimicrobial peptide (PEG-F5W, E19Q-Magainin 2-amide) based on the α-helical peptide Magainin 2 isolated from the African clawed frog Xenopus laevis. The PEGylated peptide induced the leakage of calcein from egg yolk l -α-phosphatidylglycerol/egg yolk l -α-phosphatidylcholine large unilamellar vesicles, however, the activity was weaker than that of the control peptides. The PEGylated peptide induced lipid flip-flop coupled to the leakage and was translocated into the inner leaflet of the bilayer, indicating that PEGylation did not alter the basic mechanism of membrane permeabilization of the parent peptide. The cytotoxicity of the non-PEGylated peptides was nullified by PEGylation. At the same time, the antimicrobial activity was weakened only by 4 fold. The effects of PEGylation on the activity of Magainin were compared with those for tachyplesin.
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Role of positional hydrophobicity in the leishmanicidal activity of Magainin 2.
Antimicrobial agents and chemotherapy, 2004Co-Authors: Esther Guerrero, Katsumi Matsuzaki, José María Saugar, Luis RivasAbstract:The emergence of membrane-active antimicrobial peptides as new alternatives against pathogens with multiantibiotic resistance requires the design of better analogues. Among the different physicochemical parameters involved in the optimization of linear antimicrobial peptides, positional hydrophobicity has recently been incorporated. This takes into consideration the concept of the topological distribution of hydrophobic residues throughout the sequence rather than the classical concept of hydrophobicity as a global parameter of the peptide, calculated as the summation of the individual hydrophobicities of the residues. In order to assess the contribution of this parameter to the leishmanicidal mechanisms of Magainin 2 analogues, the activities of two of these analogues, MG-H1 (GIKKFLHIIWKFIKAFVGEIMNS) and MG-H2 (IIKKFLHSIWKFGKAFVGEIMNI), which have similar charges, amino acid compositions, and hydrophobicities but different positional hydrophobicities, against Leishmania donovani promastigotes were assayed (T. Tachi, R. F. Epand, R. M. Epand, and K. Matsuzaki, Biochemistry 41:10723-10731, 2002). The activities were compared with that of the parental peptide, F5W-Magainin 2 (GIGKWLHSAKKFGKAFVGEIMNS). The three peptides were active at micromolar concentrations, in the order MG-H2 > MG-H1 > F5W-Magainin 2. These activities differ from their hemolytic and bactericidal activities. The results demonstrate that positional hydrophobicity, which reflects the presence of short stretches of sequences rich in hydrophobic amino acids, plays an important role in the activities of leishmanicidal peptides.
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Dimer structure of Magainin 2 bound to phospholipid vesicles.
Biopolymers, 2002Co-Authors: Kaori Wakamatsu, Akemi Takeda, Tomoya Tachi, Katsumi MatsuzakiAbstract:Magainin 2 from African clawed frog Xenopus laevis is an antimicrobial peptide with broad spectra and action mechanisms considered to permeabilize bacterial membranes. CD, vibration, and solid-state NMR spectroscopies indicate the peptide adopts an α-helical conformation on binding to phospholipid bilayers, and its micelle-bound conformation, being monomeric and α-helical, is well detailed. We showed, however, that the peptide dimerizes on binding to phospholipid bilayers. This difference in the conformation and aggregation state between micelle- and bilayer-bound states prompted us to analyze the conformation of an equipotent analog of Magainin 2 (F5Y,F16W Magainin 2) bound to phosphatidylcholine vesicles using transferred nuclear Overhauser enhancement (TRNOE) spectroscopy. While observed medium-range TRNOE cross peaks were characteristic of α-helix, many long-range cross peaks were not compatible with the peptide's monomeric state. Simulated annealing calculations generated dimer structures indicating (1) two peptide molecules have a largely helical conformation in antiparallel orientation forming a short coiled-coil structure, (2) residues 4–20 are well converged and residues 9–20 are in an α-helical conformation, and (3) the interface of the two peptide molecules is formed by well-defined side chains of hydrophobic residues. Finally, determined structures are compatible with numerous investigations examining Magainin–phospholipid interactions. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 314–327, 2002
Burkhard Bechinger - One of the best experts on this subject based on the ideXlab platform.
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The Reversible Non-covalent Aggregation Into Fibers of PGLa and Magainin 2 Preserves Their Antimicrobial Activity and Synergism
Frontiers in Cellular and Infection Microbiology, 2020Co-Authors: Dennis Wilkens Juhl, Elise Glattard, Morane Lointier, Panos Bampilis, Burkhard BechingerAbstract:Magainin 2 and PGLa are antimicrobial peptides found together in frog skin secretions.When added as a mixture they show an order of magnitude increase in antibacterialactivity and in model membrane permeation assays. Here we demonstrate thatboth peptides can form fibers with beta-sheet/turn signature in ATR-FTIR- andCD-spectroscopic analyses, but with different morphologies in EM images. Whereas,fiber formation results in acute reduction of the antimicrobial activity of the individualpeptides, the synergistic enhancement of activity remainsfor the equimolar mixture ofPGLa and Magainin 2 also after fibril formation. The biological significance and potentialapplications of such supramolecular aggregates are discussed.
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Highly synergistic antimicrobial activity of Magainin 2 and PGLa peptides is rooted in the formation of supramolecular complexes with lipids.
Scientific reports, 2020Co-Authors: Christopher Aisenbrey, Mariana Amaro, Petr Pospíšil, Martin Hof, Burkhard BechingerAbstract:Magainin 2 and PGLa are cationic, amphipathic antimicrobial peptides which when added as equimolar mixture exhibit a pronounced synergism in both their antibacterial and pore-forming activities. Here we show for the first time that the peptides assemble into defined supramolecular structures along the membrane interface. The resulting mesophases are quantitatively described by state-of-the art fluorescence self-quenching and correlation spectroscopies. Notably, the synergistic behavior of Magainin 2 and PGLa correlates with the formation of hetero-domains and an order-of-magnitude increased membrane affinity of both peptides. Enhanced membrane association of the peptide mixture is only observed in the presence of phophatidylethanolamines but not of phosphatidylcholines, lipids that dominate bacterial and eukaryotic membranes, respectively. Thereby the increased membrane-affinity of the peptide mixtures not only explains their synergistic antimicrobial activity, but at the same time provides a new concept to increase the therapeutic window of combinatorial drugs.
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Lipid-Mediated Interactions between the Antimicrobial Peptides Magainin 2 and PGLa in Bilayers.
Biophysical journal, 2018Co-Authors: Nicole Harmouche, Burkhard BechingerAbstract:Abstract A synergistic enhancement of activities has been described for the amphipathic cationic antimicrobial peptides Magainin 2 and PGLa when tested in antimicrobial assays or in biophysical experiments using model membranes. In the presence of Magainin 2, PGLa changes from an in-planar alignment parallel to the membrane surface to a more transmembrane orientation when investigated in membranes made from fully saturated PC or PC/PG, but not when one of the fatty acyl chains is unsaturated. Such lipid-mediated changes in the membrane topology of polypeptide domains could provide an interesting mechanism for the regulation of membrane proteins. Here we investigated the PGLa topology in a wide variety of membranes made of saturated or unsaturated PE, PC, and/or PG using 15N solid-state NMR spectroscopy. In contrast to predictions made by previous models the data show that membrane curvature has only a minor effect on PGLa realignment. Furthermore, using 2H solid-state NMR spectroscopy of deuterated phospholipid fatty acyl chains the order parameters of the lipids were investigated in the presence of PGLa, Magainin, or equimolar peptide mixtures. Both peptides cause a pronounced decrease in the order parameters when oriented parallel to the membrane surface, an effect that reverts when PGLa flips into transmembrane alignments. Taken together, these data are suggestive that the Magainin-induced disordering of fatty acyl chains provides an important driving force for PGLa realignment.
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Magainin 2-PGLa Interactions in Membranes - Two Peptides that Exhibit Synergistic Enhancement of Antimicrobial Activity.
Current topics in medicinal chemistry, 2015Co-Authors: Arnaud Marquette, Evgeniy S. Salnikov, Elise Glattard, Christopher Aisenbrey, Burkhard BechingerAbstract:The structural requirements for the synergistic enhancement of antimicrobial activities of the cationic linear peptides PGLa and Magainin 2 were investigated. In a first step the antimicrobial activities were evaluated for a number of modifications of the sequences and equimolar mixtures thereof. In particular fluorophore labelled peptides maintain a high degree of antimicrobial activity and considerable synergism when tested conjointly. Thereafter, circular dichroism spectroscopy indicated that these extended sequences adopt helical conformations in the presence of model membranes similar to the unmodified sequences. Energy transfer between the fluorophores suggested that the peptides reside in close proximity to each other when bound to the membrane surface at high concentrations. The fluorophore interactions quickly diminish at lower peptide-to-lipid ratios indicating that the peptide-peptide interactions are weak. Furthermore, 15 N solid-state NMR measurements of the membrane topology of [ 15 N-Ala14]-PGLa and of its fluorophorecarrying analogue reconstituted into supported 1, 2-didecanoyl- sn -glycero-3-phosphocholine bilayers were performed. These experiments revealed no correlation between the topological state of PGLa and the observed synergistic enhancement of antimicrobial activities due to the presence of Magainins. These results suggest that lipid mediated interactions rather than the formation of tight peptide-peptide complexes in the membrane are responsible for synergistic activities of the mixtures.
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Lipid-Controlled Peptide Topology and Interactions in Bilayers: Structural Insights into the Synergistic Enhancement of the Antimicrobial Activities of PGLa and Magainin 2
Biophysical journal, 2011Co-Authors: Evgeniy S. Salnikov, Burkhard BechingerAbstract:To gain further insight into the antimicrobial activities of cationic linear peptides, we investigated the topology of each of two peptides, PGLa and Magainin 2, in oriented phospholipid bilayers in the presence and absence of the other peptide and as a function of the membrane lipid composition. Whereas proton-decoupled 15N solid-state NMR spectroscopy indicates that Magainin 2 exhibits stable in-plane alignments under all conditions investigated, PGLa adopts a number of different membrane topologies with considerable variations in tilt angle. Hydrophobic thickness is an important parameter that modulates the alignment of PGLa. In equimolar mixtures of PGLa and Magainin 2, the former adopts transmembrane orientations in dimyristoyl-, but not 1-palmitoyl-2-oleoyl-, phospholipid bilayers, whereas Magainin 2 remains associated with the surface in all cases. These results have important consequences for the mechanistic models explaining synergistic activities of the peptide mixtures and will be discussed. The ensemble of data suggests that the thinning of the dimyristoyl membranes caused by Magainin 2 tips the topological equilibrium of PGLa toward a membrane-inserted configuration. Therefore, lipid-mediated interactions play a fundamental role in determining the topology of membrane peptides and proteins and thereby, possibly, in regulating their activities as well.
Anne S. Ulrich - One of the best experts on this subject based on the ideXlab platform.
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Molecular mechanism of synergy between the antimicrobial peptides PGLa and Magainin 2
Scientific Reports, 2017Co-Authors: Jonathan Zerweck, Erik Strandberg, Parvesh Wadhwani, Jochen Bürck, Johannes Reichert, Olga Kukharenko, Anne S. UlrichAbstract:PGLa and Magainin 2 (MAG2) are amphiphilic α-helical membranolytic peptides from frog skin with known synergistic antimicrobial activity. By systematically mutating residues in the two peptides it was possible to identify the ones crucial for the synergy, as monitored by biological assays, fluorescence vesicle leakage, and solid-state ^15N-NMR. Electrostatic interactions between anionic groups in MAG2 and cationic residues in PGLa enhance synergy but are not necessary for the synergistic effect. Instead, two Gly residues (7 and 11) in a so-called GxxxG motif in PGLa are necessary for synergy. Replacing either of them with Ala or another hydrophobic residue completely abolishes synergy according to all three methods used. The designer-made peptide MSI-103, which has a similar sequence as PGLa, shows no synergy with MAG2, but by introducing two Gly mutations it was possible to make it synergistic. A molecular model is proposed for the functionally active PGLa-MAG2 complex, consisting of a membrane-spanning antiparallel PGLa dimer that is stabilized by intimate Gly-Gly contacts, and where each PGLa monomer is in contact with one MAG2 molecule at its C-terminus.
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Homo- and heteromeric interaction strengths of the synergistic antimicrobial peptides PGLa and Magainin 2 in membranes
European Biophysics Journal, 2016Co-Authors: Jonathan Zerweck, Erik Strandberg, Parvesh Wadhwani, Jochen Bürck, Johannes Reichert, Olga Kukharenko, Anne S. UlrichAbstract:PGLa and Magainin 2 (MAG2) are amphiphilic α-helical frog peptides with synergistic antimicrobial activity. In vesicle leakage assays we observed the strongest synergy for equimolar mixtures of PGLa and MAG2. This result was consistent with solid-state ^15N-NMR data on the helix alignment in model membranes. The Hill coefficients determined from the vesicle leakage data showed that the heterodimeric (PGLa-MAG2) interactions were stronger than the homodimeric (PGLa–PGLa and MAG2-MAG2) interactions. This result was also reflected in the free energy of dimerization determined from oriented circular dichroism and quantitative solid-state ^19F-NMR analysis.
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Influence of hydrophobic residues on the activity of the antimicrobial peptide Magainin 2 and its synergy with PGLa
Journal of peptide science : an official publication of the European Peptide Society, 2015Co-Authors: Erik Strandberg, Parvesh Wadhwani, Jonathan Zerweck, Jochen Bürck, Diana Horn, Günther Pritz, Marina Berditsch, Anne S. UlrichAbstract:Magainin 2 (MAG2) and PGLa are two related antimicrobial peptides found in the skin of the African frog Xenopus laevis with a pronounced synergistic activity, which act by permeabilizing bacterial membranes. To probe the influence of hydrophobic peptide–lipid and peptide–peptide interactions on the antimicrobial activity and on synergy, the sequence of MAG2 was modified by replacing single amino acids either with a small alanine or with the stiff and bulky hydrophobic 3-(trifluoromethyl)-L-bicyclopent-[1.1.1]-1-ylglycine side chain. The minimum inhibitory concentration of 14 MAG2 analogs was strongly influenced by these single substitutions: the antimicrobial activity was consistently improved when the hydrophobicity was increased on the hydrophobic face of the amphiphilic helix, while the activity decreased when the hydrophobicity was reduced. The synergy with PGLa, on the other hand, was rather insensitive to mutations of hydrophobic residues. It thus seems that the antimicrobial effect of MAG2 on its own depends strongly on the hydrophobicity of the peptide, while the synergy with PGLa does not depend on the overall hydrophobicity of MAG2. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.
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synergistic transmembrane insertion of the heterodimeric pgla Magainin 2 complex studied by solid state nmr
Biochimica et Biophysica Acta, 2009Co-Authors: Erik Strandberg, Pierre Tremouilhac, Parvesh Wadhwani, Anne S. UlrichAbstract:Abstract The skin secretions of amphibians are a rich source of antimicrobial peptides. The two antimicrobial peptides PGLa and Magainin 2, isolated from the African frog Xenopus laevis, have been shown to act synergistically by permeabilizing the membranes of microorganisms. In this report, the literature on PGLa is extensively reviewed, with special focus on its synergistically enhanced activity in the presence of Magainin 2. Our recent solid state 2H NMR studies of the orientation of PGLa in lipid membranes alone and in the presence of Magainin 2 are described in detail, and some new data from 3,3,3-2H3-L-alanine labeled PGLa are included in the analysis.
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Synergistic transmembrane insertion of the heterodimeric PGLa/Magainin 2 complex studied by solid-state NMR.
Biochimica et biophysica acta, 2009Co-Authors: Erik Strandberg, Pierre Tremouilhac, Parvesh Wadhwani, Anne S. UlrichAbstract:Abstract The skin secretions of amphibians are a rich source of antimicrobial peptides. The two antimicrobial peptides PGLa and Magainin 2, isolated from the African frog Xenopus laevis, have been shown to act synergistically by permeabilizing the membranes of microorganisms. In this report, the literature on PGLa is extensively reviewed, with special focus on its synergistically enhanced activity in the presence of Magainin 2. Our recent solid state 2H NMR studies of the orientation of PGLa in lipid membranes alone and in the presence of Magainin 2 are described in detail, and some new data from 3,3,3-2H3-L-alanine labeled PGLa are included in the analysis.
Koichiro Miyajima - One of the best experts on this subject based on the ideXlab platform.
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Mechanism of Synergism between Antimicrobial Peptides Magainin 2 and PGLa
Biochemistry, 1998Co-Authors: Katsumi Matsuzaki, Osamu Murase, Yasuyuki Mitani, Ken’ya Akada, Shuji Yoneyama, Michael Zasloff, Koichiro MiyajimaAbstract:The antimicrobial peptides Magainin 2 and PGLa, discovered in the skin of the African clawed frog, Xenopus laevis, exhibit marked synergism [Westerhoff, H. V., Zasloff, M., Rosner, J. L., Hendler, R. W., de Waal, A., Vaz Gomes, A., Jongsma, A. P. M., Riethorst, A., and Juretic, D., Eur. J. Biochem. 228, 257-264 (1995)], although the mechanism is not yet clear. They are believed to kill bacteria by permeabilizing membranes. In this study, we examined the interactions of these peptides in lipid bilayers. PGLa, like Magainin 2, preferentially interacts with acidic lipids, forming an amphipathic helix. The peptide induces the release of a water-soluble dye, calcein, entrapped within liposomes. The coexistence of Magainin 2 enhances membrane permeabilization, which is maximal at a 1:1 molar ratio. Fluorescence experiments using L18W-PGLa revealed that both peptides form a stoichiometric 1:1 complex in the membrane phase with an association free energy of -15 kJ/mol. Single amino acid mutations in Magainin 2 significantly altered the synergistic activity, suggesting that precise molecular recognition is involved in complex formation. The complex as well as each component peptide form peptide-lipid supramolecular complex pores, which mediate the mutually coupled transbilayer transport of dye, lipid, and the peptide per se. The rate of pore formation rate is in the order complex >/= PGLa > Magainin 2, whereas the pore lifetime is in the order Magainin 2 > complex > PGLa. Therefore, the synergism is a consequence of the formation of a potent heterosupramolecular complex, which is characterized by fast pore formation and moderate pore stability.
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Relationship of membrane curvature to the formation of pores by Magainin 2.
Biochemistry, 1998Co-Authors: Katsumi Matsuzaki, Ken-ichi Sugishita, Koichiro Miyajima, Noriko Ishibe, Mayu Ueha, Saori Nakata, Richard M. EpandAbstract:Magainin 2, an antimicrobial peptide from the Xenopus skin, kills bacteria by permeabilizing the cell membranes. We have proposed that the peptide preferentially interacts with acidic phospholipids to form a peptide-lipid supramolecular complex pore, which allows mutually coupled transbilayer traffic of ions, lipids, and peptides, thus simultaneously dissipating transmembrane potential and lipid asymmetry [Matsuzaki, K., Murase, O., Fujii, N., and Miyajima, K. (1996) Biochemistry 35, 11361-11368]. In this paper, we examined the effect of membrane curvature strain on pore formation. Magainin effectively forms the pore only in phosphatidylglycerol bilayers at low peptide-to-lipid ratios, well below 1/100. In contrast, the permeabilization of phosphatidylserine, phosphatidic acid, or cardiolipin bilayers occurred at much higher peptide-to-lipid ratios (1/50 to 1/10) with some morphological change of the vesicles. The latter three classes of phospholipids are known to form hexagonal II structures under conditions of reduced interlipid electrostatic repulsions. Incorporation of phosphatidylethanolamine also inhibited the Magainin-induced pore formation in the inhibitory order of dioleoylphosphatidylethanolamine > dielaidoylphosphatidylethanolamine. Addition of a small amount of palmitoyllysophosphatidylcholine enhanced the peptide-induced permeabilization of phosphatidylglycerol bilayers. Magainin greatly raised the bilayer to hexagonal II phase transition temperature of dipalmitoleoylphosphatidylethanolamine. These results suggest that the peptide imposes positive curvature strain, facilitating the formation of a torus-type pore, and that the presence of negative curvature-inducing lipids inhibits pore formation.
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Interactions of an antimicrobial peptide, Magainin 2, with outer and inner membranes of Gram-negative bacteria
Biochimica et biophysica acta, 1997Co-Authors: Katsumi Matsuzaki, Ken-ichi Sugishita, Nobutaka Fujii, Mitsunori Harada, Koichiro MiyajimaAbstract:Magainin peptides, isolated from Xenopus skin, have broad spectra of antimicrobial activity and low toxicities to normal eukaryotic cells, thus being good candidates for therapeutic agents. The mechanism of action is considered to be the permeabilization of bacterial membranes. A number of studies using lipid vesicles have elucidated its molecular detail. However, their interactions with bacteria are not yet well understood. In this paper, we synthesized several Magainin analogs with different charges (0 to +6) and hydrophobicities, and systematically studied their interactions with the outer and inner membranes of three species of Gram-negative bacteria (Escherichia coli, Acinetobacter calcoaceticus, Proteus vulgaris). The treatment of the E. coli cells with native Magainin 2 (+4) immediately induced the efflux of the intracellular K+ ions and the cell death. A number of blebs were formed on the bacterial surface and the outer membrane became leaky. An increase in the peptide's positive charge enhanced the outer membrane permeabilization and the bactericidal activity. The cationic peptides also effectively permeabilized the inner membranes rich in acidic phospholipids, indicating the importance of electrostatic interactions. Substitution of Trp for Phe simultaneously increased the bactericidal activity and the hemolytic activity. A strategy to develop potent antimicrobial peptides was discussed on the basis of these results.
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Modulation of Magainin 2-lipid bilayer interactions by peptide charge.
Biochemistry, 1997Co-Authors: Katsumi Matsuzaki, Akemi Nakamura, Osamu Murase, Ken-ichi Sugishita, Nobutaka Fujii, Koichiro MiyajimaAbstract:Magainin 2, an antimicrobial peptide from Xenopus skin, assumes an amphiphilic helix when bound to acidic phospholipids, forming a pore composed of a dynamic, peptide−lipid supramolecular complex [Matsuzaki et al. (1996) Biochemistry 35, 11361−11368]. Upon the disintegration of the pore, a fraction of the peptide molecules stochastically translocates across the bilayer (Matsuzaki, et al., 1995). In order to investigate the effects of peptide charge on the Magainin 2−lipid bilayer interactions, we synthesized four Magainin 2 analogs with different charges (0−6+). MG0: K10E, K11E, F12W-Magainin 2. MG2+: K10E, F12W-Magainin 2. MG4+: F12W-Magainin 2. MG6+: F12W, E19Q-Magainin 2 amide. An increase in charge resulted in a stronger binding of the peptide to the negatively charged membranes, suggesting that electrostatic attractions play a crucial role in the binding process. The helical stability in a trifluoroethanol/buffer mixture was decreased with increasing positive charge because of electrostatic repul...
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an antimicrobial peptide Magainin 2 induced rapid flip flop of phospholipids coupled with pore formation and peptide translocation
Biochemistry, 1996Co-Authors: Katsumi Matsuzaki, Osamu Murase, And Nobutaka Fujii, Koichiro MiyajimaAbstract:The effect of an antimicrobial peptide, Magainin 2, on the flip-flop rates of phospholipids was investigated by use of fluorescent lipids, i.e., anionic N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)dipalmitoyl-l-α-phosphatidylethanolamine (NBD-PE), 1-oleoyl-2-[12-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dodecanoyl]-l-α-phosphatidic acid (C12-NBD-PA), 1-oleoyl-2-[12-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dodecanoyl]-l-α-phosphatidyl-l-serine (C12-NBD-PS), and zwitterionic 1-palmitoyl-2-[6-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)caproyl]-l-α-phosphatidylcholine (C6-NBD-PC). Their intrinsic flip-flop half-lives at 30 °C in the absence of the peptide were 1.1 h, ca. 7 h, ca. 8 days, and >2 days, respectively. The peptide accelerated the flip-flop half-lives of the fluorescent lipids to an order of minutes. Furthermore, the flip-flop was coupled with the membrane permeabilization and the peptide translocation [Matsuzaki, K., Murase, O., Fujii, N., & Miyajima, K. (1995) Biochemistry 34, 6521−6526], suggesting por...
Jack Blazyk - One of the best experts on this subject based on the ideXlab platform.
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Interactions between the antimicrobial peptide, Magainin 2, and Salmonella typhimurium lipopolysaccharides.
FEBS letters, 1991Co-Authors: Fazale R. Rana, Jack BlazykAbstract:Using FT-IR spectroscopy, the effects of Magainin 2 on the thermotropic behavior of LPS isolated from wild-type (SL3770) and LPS-mutant strains of Salmonella typhimurium are characterized and compared. The mutant strains include Ra (SL3749), polymyxin-sensitive Rb2(s) (SH5014), polymyxin-resistant Rb2(r) (SH5357) and Rc (HN202) LPS chemotypes, whose polysaccharide chains differ in length but possess an identical number of phosphorylation sites. In all cases, Magainin 2 causes a concentration-dependent disordering of the LPS fatty acyl chains. Differences in disordering of LPS correlate more closely with the charge on the LPS molecule (determined by high-resolution 31P NMR) rather than with the length of the LPS sugar side chain, contradicting the currently accepted model for the interaction of cationic antibiotics with the Gram-negative cell envelope.
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Interactions between Magainin 2 and salmonella typhimurium outer membranes effect of lipopolysaccharide structure
Biochemistry, 1991Co-Authors: Fazale R. Rana, Elizabeth A. Macias, Catherine M. Sultany, Malcolm C. Modzrakowski, Jack BlazykAbstract:The role of the outer membrane and lipopolysaccharide (LPS) in the interaction between the small cationic antimicrobial peptide Magainin 2 and the Gram-negative cell envelope was studied by FT-IR spectroscopy. Magainin 2 alters the thermotropic properties of the outer membrane-peptidoglycan complexes from wild-type Salmonella typhimurium and a series of LPS mutants which display differential susceptibility to the bactericidal activity of cationic antibiotics. These results are correlated with the LPS phosphorylation pattern and charge (characterized by high-resolution {sup 31}P NMR) and outer membrane lipid composition, and are compared to the bactericidal susceptibility. LPS mutants show a progressive loss of resistance to killing by Magainin 2 as the length of the LPS polysaccharide moiety decreases. Disordering of the outer membrane lipid fatty acyl chains by Magainin 2, however, depends primarily upon the magnitude of PLS charge rather than the length of the LPS polysaccharide. While disruption of outer membrane structure most likely is not the primary factor leading to cell death, the susceptibility of Gram-negative cells to Magainin 2 is associated with factors that facilitate the transport of the peptide across the outer membrane, such as the magnitude and location of LPS charge, and concentration of LPS in the outer membrane, outermore » membrane molecular architecture, and the presence or absence of the O-antigen side chain.« less
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Bactericidal activity of Magainin 2: use of lipopolysaccharide mutants.
Canadian journal of microbiology, 1990Co-Authors: Elizabeth A. Macias, Fazale R. Rana, Jack Blazyk, Malcolm C. ModrzakowskiAbstract:Salmonella typhimurium and a series of rough lipopolysaccharide mutants derived from it were used as target bacteria to examine the antimicrobial capacity of Magainin 2. Magainin 2 demonstrated a dose-related bactericidal activity against the smooth parent strain and the series of lipopolysaccharide mutants. The lipopolysaccharide mutant series showed an ordered increase in sensitivity to the Magainin 2 as the depth of the rough lesion in the lipopolysaccharide increased. Key words: Salmonella typhimurium, lipopolysaccharide, antimicrobial capacity, Magainin.
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Interactions between Salmonella typhimurium lipopolysaccharide and the antimicrobial peptide, Magainin 2 amide.
FEBS Letters, 1990Co-Authors: Fazale R. Rana, Catherine M. Sultany, Jack BlazykAbstract:Effects of Magainin 2 amide on the phase behavior of Salmonella typhimurium lipopolysaccharide were characterized by FT-IR spectroscopy. This antimicrobial cationic peptide disorders the lipopolysaccharide at molecular ratios of lipopolysaccharide to Magainin greater than 4, and can induce a temperature-dependent structural reorientation. The nature of the five phosphate groups of lipopolysaccharide was determined by 31P NMR spectroscopy. At pH 7.4, the net charge on the phosphates is −7. Lipopolysaccharide undoubtedly plays an important role in modulating the interactions of Magainin with the gram-negative cell envelope and may act as a molecular sponge to protect the plasma membrane.
