101
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Salnikov ES, Bechinger B. Lipid-controlled peptide topology and interactions in bilayers: structural insights into the synergistic enhancement of the antimicrobial activities of PGLa and magainin 2. Biophys J 2011; 100:1473-80. [PMID: 21402029 DOI: 10.1016/j.bpj.2011.01.070] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 12/27/2010] [Accepted: 01/31/2011] [Indexed: 11/28/2022] Open
Abstract
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 (15)N 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.
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Affiliation(s)
- Evgeniy S Salnikov
- Université de Strasbourg/Centre National de la Recherche Scientifique, Institut de Chimie, Strasbourg, France
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102
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Melzer S, Clerens S, Bishop PJ. Differential polymorphism in cutaneous glands of archaic Leiopelma species. J Morphol 2011; 272:1116-30. [DOI: 10.1002/jmor.10960] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Revised: 01/24/2011] [Accepted: 02/20/2011] [Indexed: 11/08/2022]
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103
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Nguyen LT, Haney EF, Vogel HJ. The expanding scope of antimicrobial peptide structures and their modes of action. Trends Biotechnol 2011; 29:464-72. [PMID: 21680034 DOI: 10.1016/j.tibtech.2011.05.001] [Citation(s) in RCA: 1047] [Impact Index Per Article: 80.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/27/2011] [Accepted: 05/04/2011] [Indexed: 11/17/2022]
Abstract
Antimicrobial peptides (AMPs) are an integral part of the innate immune system that protect a host from invading pathogenic bacteria. To help overcome the problem of antimicrobial resistance, cationic AMPs are currently being considered as potential alternatives for antibiotics. Although extremely variable in length, amino acid composition and secondary structure, all peptides can adopt a distinct membrane-bound amphipathic conformation. Recent studies demonstrate that they achieve their antimicrobial activity by disrupting various key cellular processes. Some peptides can even use multiple mechanisms. Moreover, several intact proteins or protein fragments are now being shown to have inherent antimicrobial activity. A better understanding of the structure-activity relationships of AMPs is required to facilitate the rational design of novel antimicrobial agents.
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Affiliation(s)
- Leonard T Nguyen
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada, T2N 1N4
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104
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Chan CS, Haney EF, Vogel HJ, Turner RJ. Towards understanding the Tat translocation mechanism through structural and biophysical studies of the amphipathic region of TatA from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2289-96. [PMID: 21683683 DOI: 10.1016/j.bbamem.2011.05.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/11/2011] [Accepted: 05/30/2011] [Indexed: 12/19/2022]
Abstract
The twin-arginine translocase (Tat) system is used by many bacteria and plants to move folded proteins across the cytoplasmic or thylakoid membrane. In most bacteria, the TatA protein is believed to form a defined pore in the membrane through homo-oligomerization with other TatA protomers. The predicted secondary structure of TatA includes a transmembrane helix, an amphipathic helix, and an unstructured C-terminal region. Here biophysical and structural investigations were performed on a synthetic peptide representing the amphipathic region of TatA (residues 22 to 44, abbreviated TatAH2). The C-terminal region of TatA (residues 44-89) was previously shown to be accessible from both the cytoplasmic and periplasmic sides of the membrane only when the membrane potential was intact, suggesting dependence of its topology on an energized membrane (Chan et al. 2007 Biochemistry 46: 7396-404). Such observation suggests that the TatAH2 region would have unique lipid interactions that may be related to the function of TatA during translocation and thus warranted further investigations. NMR and CD spectroscopy of TatAH2 show that it adopts a predominantly helical structure in a membrane environment while remaining unstructured in aqueous solution. Differential scanning calorimetry studies also reveal that TatAH2 interacts with DPPG lipids but not with DPPC, suggesting that negatively charged phospholipid head groups contribute to the membrane interactions with TatA.
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Affiliation(s)
- Catherine S Chan
- Biochemistry Research Cluster, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
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105
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Bechinger B. Insights into the mechanisms of action of host defence peptides from biophysical and structural investigations. J Pept Sci 2011; 17:306-14. [DOI: 10.1002/psc.1343] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 11/12/2010] [Accepted: 11/15/2010] [Indexed: 01/09/2023]
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106
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Knowledge-based computational methods for identifying or designing novel, non-homologous antimicrobial peptides. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 40:371-85. [DOI: 10.1007/s00249-011-0674-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 12/16/2010] [Accepted: 01/04/2011] [Indexed: 02/07/2023]
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107
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Wieczorek M, Jenssen H, Kindrachuk J, Scott WRP, Elliott M, Hilpert K, Cheng JTJ, Hancock REW, Straus SK. Structural studies of a peptide with immune modulating and direct antimicrobial activity. ACTA ACUST UNITED AC 2011; 17:970-80. [PMID: 20851346 DOI: 10.1016/j.chembiol.2010.07.007] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Revised: 07/03/2010] [Accepted: 07/07/2010] [Indexed: 01/17/2023]
Abstract
The structure and function of the synthetic innate defense regulator peptide 1018 was investigated. This 12 residue synthetic peptide derived by substantial modification of the bovine cathelicidin bactenecin has enhanced innate immune regulatory and moderate direct antibacterial activities. The solution state NMR structure of 1018 in zwitterionic dodecyl phosphocholine (DPC) micelles indicated an α-helical conformation, while secondary structures, based on circular dichroism measurements, in anionic sodium dodecyl sulfate (SDS) and phospholipid vesicles (POPC/PG in a 1:1 molar ratio) and simulations revealed that 1018 can adopt a variety of folds, tailored to its different functions. The structural data are discussed in light of the ability of 1018 to potently induce chemokine responses, suppress the LPS-induced TNF-α response, and directly kill both Gram-positive and Gram-negative bacteria.
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Affiliation(s)
- Michal Wieczorek
- Chemistry Department, University of British Columbia, Vancouver, BC, Canada
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108
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Qureshi T, Goto NK. Contemporary methods in structure determination of membrane proteins by solution NMR. Top Curr Chem (Cham) 2011; 326:123-85. [PMID: 22160391 DOI: 10.1007/128_2011_306] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Integral membrane proteins are vital to life, being responsible for information and material exchange between a cell and its environment. Although high-resolution structural information is needed to understand how these functions are achieved, membrane proteins remain an under-represented subset of the protein structure databank. Solution NMR is increasingly demonstrating its ability to help address this knowledge shortfall, with the development of a diverse array of techniques to counter the challenges presented by membrane proteins. Here we document the advances that are helping to define solution NMR as an effective tool for membrane protein structure determination. Developments introduced over the last decade in the production of isotope-labeled samples, reconstitution of these samples into the growing selection of NMR-compatible membrane-mimetic systems, and the approaches used for the acquisition and application of structural restraints from these complexes are reviewed.
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Affiliation(s)
- Tabussom Qureshi
- Department of Chemistry, University of Ottawa, Ottawa, ON, Canada
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109
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Domadia PN, Bhunia A, Ramamoorthy A, Bhattacharjya S. Structure, interactions, and antibacterial activities of MSI-594 derived mutant peptide MSI-594F5A in lipopolysaccharide micelles: role of the helical hairpin conformation in outer-membrane permeabilization. J Am Chem Soc 2010; 132:18417-28. [PMID: 21128620 DOI: 10.1021/ja1083255] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lipopolysaccharide (LPS) provides a well-organized permeability barrier at the outer membrane of Gram-negative bacteria. Host defense cationic antimicrobial peptides (AMPs) need to disrupt the outer membrane before gaining access to the inner cytoplasmic membrane or intracellular targets. Several AMPs are largely inactive against Gram-negative pathogens due to the restricted permeation through the LPS layer of the outer membrane. MSI-594 (GIGKFLKKAKKGIGAVLKVLTTG) is a highly active AMP with a broad-spectrum of activities against bacteria, fungi, and virus. In the context of LPS, MSI-594 assumes a hairpin helical structure dictated by packing interactions between two helical segments. Residue Phe5 of MSI-594 has been found to be engaged in important interhelical interactions. In order to understand plausible structural and functional inter-relationship of the helical hairpin structure of MSI-594 with outer membrane permeabilization, a mutant peptide, termed MSI-594F5A, containing a replacement of Phe5 with Ala has been prepared. We have compared antibacterial activities, outer and inner membrane permeabilizations, LPS binding affinity, perturbation of LPS micelles structures by MSI-594 and MSI-594F5A peptides. Our results demonstrated that the MSI-594F5A has lower activities against Gram-negative bacteria, due to limited permeabilization through the LPS layer, however, retains Gram-positive activity, akin to MSI-594. The atomic-resolution structure of MSI-594F5A has been determined in LPS micelles by NMR spectroscopy showing an amphipathic curved helix without any packing interactions. The 3D structures, interactions, and activities of MSI-594 and its mutant MSI-594F5A in LPS provide important mechanistic insights toward the requirements of LPS specific conformations and outer membrane permeabilization by broad-spectrum antimicrobial peptides.
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Affiliation(s)
- Prerna N Domadia
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore-637551
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110
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Saravanan R, Bhattacharjya S. Oligomeric structure of a cathelicidin antimicrobial peptide in dodecylphosphocholine micelle determined by NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:369-81. [PMID: 20933496 DOI: 10.1016/j.bbamem.2010.10.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 09/24/2010] [Accepted: 10/04/2010] [Indexed: 01/05/2023]
Abstract
The broad spectrum of antibacterial activities of host defense cationic antimicrobial peptides (AMPs) arises from their ability to perturb membrane integrity of the microbes. The mechanisms are often thought to require assembly of AMPs on the membrane surface to form pores. However, three dimensional structures in the oligomeric form of AMPs in the context of lipid membranes are largely limited. Here, we demonstrate that a 22-residue antimicrobial peptide, termed VK22, derived from fowlicidin-1, a cathelicidin family of AMP from chicken oligomerizes into a predominantly tetrameric state in zwitterionic dodecylphosphocholine (DPC) micelles. An ensemble of NMR structures of VK22 determined in 200mM perdeuterated DPC, from 755 NOE constrains including 19 inter-helical NOEs, had revealed an assembly of four helices arranged in anti-parallel fashion. Hydrogen bonds, C(α)H-O=C types, and van der Waals interactions among the helical sub-units appear to be involved in the stabilization of the quaternary structures. The central region of the barrel shaped tetrameric bundle is non-polar with clusters of aromatic residues, whereas all the cationic residues are positioned at the termini. Paramagnetic spin labeled NMR experiments indicated that the tetrameric structure is embedded into micelles such that the non-polar region located inside the lipid acyl chains. Structure and micelle localization of a monomeric version, obtained from substitution of two Tyr residues with Ala, of the peptide is also compared. The mutated peptide VK22AA has been found be localized at the surface of the micelles. The tetrameric structure of VK22 delineates a small water pore that can be larger in the higher order oligomers. As these results provide structural insights, at atomic resolution, into the oligomeric states of a helical AMP in lipid environment, the structural details may be further utilized for the design of novel self-assembled membrane protein mimics.
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Affiliation(s)
- Rathi Saravanan
- School of Biological Sciences, Division of Structural and Computational Biology, Nanyang Technological University, Singapore 637551, Singapore
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111
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Bellemare A, Vernoux N, Morin S, Gagné SM, Bourbonnais Y. Structural and antimicrobial properties of human pre-elafin/trappin-2 and derived peptides against Pseudomonas aeruginosa. BMC Microbiol 2010; 10:253. [PMID: 20932308 PMCID: PMC2958999 DOI: 10.1186/1471-2180-10-253] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 10/08/2010] [Indexed: 11/10/2022] Open
Abstract
Background Pre-elafin/trappin-2 is a human innate defense molecule initially described as a potent inhibitor of neutrophil elastase. The full-length protein as well as the N-terminal "cementoin" and C-terminal "elafin" domains were also shown to possess broad antimicrobial activity, namely against the opportunistic pathogen P. aeruginosa. The mode of action of these peptides has, however, yet to be fully elucidated. Both domains of pre-elafin/trappin-2 are polycationic, but only the structure of the elafin domain is currently known. The aim of the present study was to determine the secondary structures of the cementoin domain and to characterize the antibacterial properties of these peptides against P. aeruginosa. Results We show here that the cementoin domain adopts an α-helical conformation both by circular dichroism and nuclear magnetic resonance analyses in the presence of membrane mimetics, a characteristic shared with a large number of linear polycationic antimicrobial peptides. However, pre-elafin/trappin-2 and its domains display only weak lytic properties, as assessed by scanning electron micrography, outer and inner membrane depolarization studies with P. aeruginosa and leakage of liposome-entrapped calcein. Confocal microscopy of fluorescein-labeled pre-elafin/trappin-2 suggests that this protein possesses the ability to translocate across membranes. This correlates with the finding that pre-elafin/trappin-2 and elafin bind to DNA in vitro and attenuate the expression of some P. aeruginosa virulence factors, namely the biofilm formation and the secretion of pyoverdine. Conclusions The N-terminal cementoin domain adopts α-helical secondary structures in a membrane mimetic environment, which is common in antimicrobial peptides. However, unlike numerous linear polycationic antimicrobial peptides, membrane disruption does not appear to be the main function of either cementoin, elafin or full-length pre-elafin/trappin-2 against P. aeruginosa. Our results rather suggest that pre-elafin/trappin-2 and elafin, but not cementoin, possess the ability to modulate the expression of some P.aeruginosa virulence factors, possibly through acting on intracellular targets.
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Affiliation(s)
- Audrey Bellemare
- Département de Biochimie, Microbiologie et Bio-informatique, Institut de Biologie Intégrative et des Systèmes and Regroupement PROTEO, Université Laval, Québec, Canada
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112
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Subasinghage AP, Green BD, Flatt PR, Irwin N, Hewage CM. Metabolic and structural properties of human obestatin {1-23} and two fragment peptides. Peptides 2010; 31:1697-705. [PMID: 20553778 DOI: 10.1016/j.peptides.2010.05.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/21/2010] [Accepted: 05/21/2010] [Indexed: 12/26/2022]
Abstract
Obestatin is a peptide produced in the oxyntic mucosa of the stomach and co-localizes with ghrelin on the periphery of pancreatic islets. Several studies demonstrate that obestatin reduces food and water intake, decreases body weight gain, inhibits gastrointestinal motility, and modulates glucose-induced insulin secretion. In this study we evaluated the acute metabolic effects of human obestatin {1-23} and fragment peptides {1-10} or {11-23} in high-fat fed mice, and then investigated their solution structure by NMR spectroscopy and molecular modelling. Obestatins {1-23} and {11-23} significantly reduced food intake (86% and 90% respectively) and lowered glucose responses to feeding, whilst leaving insulin responses unchanged. No metabolic changes could be detected following the administration of obestatin {1-10}. In aqueous solution none of the obestatin peptides possessed secondary structural features. However, in a 2,2,2-trifluoroethanol (TFE-d(3))-H(2)O solvent mixture, the structure of obestatin {1-23} was characterized by an alpha-helix followed by a single turn helix conformation between residues Pro(4) and Gln(15) and His(19) and Ala(22) respectively. Obestatin {1-10} showed no structural components whereas {11-23} contained an alpha-helix between residues Val(14) and Ser(20) in a mixed solvent. These studies are the first to elucidate the structure of human obestatin and provide clear evidence that the observed alpha-helical structures are critical for in vivo activity. Future structure/function studies may facilitate the design of novel therapeutic agents based on the obestatin peptide structure.
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Affiliation(s)
- Anusha P Subasinghage
- UCD School of Biomolecular and Biomedical Science, Centre for Synthesis and Chemical Biology, SEC Strategic Research Cluster, UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
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113
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Verardi R, Traaseth NJ, Shi L, Porcelli F, Monfregola L, De Luca S, Amodeo P, Veglia G, Scaloni A. Probing membrane topology of the antimicrobial peptide distinctin by solid-state NMR spectroscopy in zwitterionic and charged lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:34-40. [PMID: 20719234 DOI: 10.1016/j.bbamem.2010.08.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 07/26/2010] [Accepted: 08/09/2010] [Indexed: 11/26/2022]
Abstract
Distinctin is a 47-residue antimicrobial peptide, which interacts with negatively charged membranes and is active against Gram-positive and Gram-negative bacteria. Its primary sequence comprises two linear chains of 22 (chain 1) and 25 (chain 2) residues, linked by a disulfide bridge between Cys19 of chain 1 and Cys23 of chain 2. Unlike other antimicrobial peptides, distinctin in the absence of the lipid membrane has a well-defined three-dimensional structure, which protects it from protease degradation. Here, we used static solid-state NMR spectroscopy in mechanically aligned lipid bilayers (charged or zwitterionic) to study the topology of distinctin in lipid bilayers. We found that this heterodimeric peptide adopts an ordered conformation absorbed on the surface of the membrane, with the long helix (chain 2), approximately parallel to the lipid bilayer (~5° from the membrane plane) and the short helix (chain 1) forming a ~24° angle with respect to the bilayer plane. Since the peptide does not disrupt the macroscopic alignment of charged or zwitterionic lipid bilayers at lipid-to-protein molar ratio of 50:1, it is possible that higher peptide concentrations might be needed for pore formation, or alternatively, distinctin elicits its cell disruption action by another mechanism.
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Affiliation(s)
- Raffaello Verardi
- Departments of Chemistry and Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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114
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Kim JK, Lee SA, Shin S, Lee JY, Jeong KW, Nan YH, Park YS, Shin SY, Kim Y. Structural flexibility and the positive charges are the key factors in bacterial cell selectivity and membrane penetration of peptoid-substituted analog of Piscidin 1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1913-25. [PMID: 20603100 DOI: 10.1016/j.bbamem.2010.06.026] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 06/11/2010] [Accepted: 06/25/2010] [Indexed: 01/25/2023]
Abstract
Piscidin 1 (Pis-1) is a novel cytotoxic peptide with a cationic alpha-helical structure isolated from the mast cells of hybrid striped bass. In our previous study, we showed that Pis-1[PG] with a substitution of Pro(8) for Gly(8) in Pis-1 had higher bacterial cell selectivity than Pis-1. We designed peptoid residue-substituted peptide, Pis-1[NkG], in which Gly(8) of Pis-1 was replaced with Nlys (Lys peptoid residue). Pis-1[NkG] had higher antibacterial activity and lower cytotoxicity against mammalian cells than Pis-1 and Pis-1[PG]. We determined the tertiary structure of Pis-1[PG] and Pis-1[NkG] in the presence of DPC micelles by NMR spectroscopy. Both peptides had a three-turn helix in the C-terminal region and a bent structure in the center. Pis-1[PG] has a rigid bent structure at Pro(8) whereas Pis-1[NkG] existed as a dynamic equilibrium of two conformers with a flexible hinge structure at Nlys(8). Depolarization of the membrane potential of Staphylococcus aureus and confocal laser-scanning microscopy study revealed that Pis-1[NkG] effectively penetrated the bacterial cell membrane and accumulated in the cytoplasm, whereas Pis-1[PG] did not penetrate the membrane but remained outside or on the cell surface. Introduction of a lysine peptoid at position 8 of Pis-1 provided conformational flexibility and increased the positive charge at the hinge region; both factors facilitated penetration of the bacterial cell membrane and conferred bacterial cell selectivity on Pis-1[NkG].
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Affiliation(s)
- Jin-Kyoung Kim
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea
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115
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Conformational Analysis of a Synthetic Antimicrobial Peptide in Water and Membrane-Mimicking Solvents: A Molecular Dynamics Simulation Study. Int J Pept Res Ther 2010. [DOI: 10.1007/s10989-010-9211-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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116
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Induction of non-lamellar lipid phases by antimicrobial peptides: a potential link to mode of action. Chem Phys Lipids 2010; 163:82-93. [PMID: 19799887 DOI: 10.1016/j.chemphyslip.2009.09.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 09/04/2009] [Accepted: 09/23/2009] [Indexed: 12/24/2022]
Abstract
Antimicrobial peptides are naturally produced by numerous organisms including insects, plants and mammals. Their non-specific mode of action is thought to involve the transient perturbation of bacterial membranes but the molecular mechanism underlying the rearrangement of the lipid molecules to explain the formation of pores and micelles is still poorly understood. Biological membranes mostly adopt planar lipid bilayers; however, antimicrobial peptides have been shown to induce non-lamellar lipid phases which may be intimately linked to their proposed mechanisms of action. This paper reviews antimicrobial peptides that alter lipid phase behavior in three ways: peptides that induce positive membrane curvature, peptides that induce negative membrane curvature and peptides that induce cubic lipid phases. Such structures can coexist with the bilayer structure, thus giving rise to lipid polymorphism induced upon addition of antimicrobial peptides. The discussion addresses the implications of induced lipid phases for the mode of action of various antimicrobial peptides.
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117
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Saviello MR, Malfi S, Campiglia P, Cavalli A, Grieco P, Novellino E, Carotenuto A. New Insight into the Mechanism of Action of the Temporin Antimicrobial Peptides. Biochemistry 2010; 49:1477-85. [DOI: 10.1021/bi902166d] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Maria Rosaria Saviello
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, I-80131 Naples, Italy
| | - Stefania Malfi
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, I-80131 Naples, Italy
| | - Pietro Campiglia
- Department of Pharmaceutical Science, University of Salerno, I-84084 Fisciano, Salerno, Italy
| | - Andrea Cavalli
- Department of Pharmaceutical Science, University of Bologna, I-40126 Bologna, Italy
- Department of Drug Discovery and Development, Italian Institute of Technology, I-16163 Genova, Italy
| | - Paolo Grieco
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, I-80131 Naples, Italy
| | - Ettore Novellino
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, I-80131 Naples, Italy
| | - Alfonso Carotenuto
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, I-80131 Naples, Italy
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118
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Kosol S, Zangger K. Dynamics and orientation of a cationic antimicrobial peptide in two membrane-mimetic systems. J Struct Biol 2010; 170:172-9. [PMID: 20045466 PMCID: PMC7128155 DOI: 10.1016/j.jsb.2009.12.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/21/2009] [Accepted: 12/28/2009] [Indexed: 01/23/2023]
Abstract
In order to investigate the functional and structural properties of cationic α-helical peptides in two different membranes, we studied the 20-residue peptide maximin H6 in two membrane-mimetic systems by NMR spectroscopy using partially 15N-labeled peptide and paramagnetic relaxation enhancements. Maximin H6, which is found in skin secretions of frogs of the Bombinae family, attacks gram-negative bacteria and acts haemolytically. While the peptide spontaneously folds into similar structures in both neutral dodecylphosphocholine (DPC) and negatively charged sodium dodecyl sulphate (SDS) micelles, its structure is more flexible in SDS as shown by 15N relaxation measurements. In addition, it is bound closer to the surface of the micelle and rotated by ∼70° around its helix axis in the negatively charged membrane surrogate compared to the structure in DPC. This might form the basis for peptide–peptide interactions through a GxxxG motif, which could finally lead to membrane disruption and, thus, preferential attack of negatively charged microbial cell walls.
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Affiliation(s)
- Simone Kosol
- Institute of Chemistry/Organic and Bioorganic Chemistry, University of Graz, Heinrichstrasse 28, A-8010 Graz, Austria.
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119
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Abstract
Membrane-active peptides or protein segments play an important role in many biological processes at the cellular interface to the environment. They are involved, e.g., in cellular fusion or host defense, where they can cause not only merging but also the destabilization of cell membranes. Many factors determine how these typically amphipathic peptides interact with the lipid bilayer. For example, the peptide orientation in the membrane determines which parts of the peptide are exposed to the hydrophobic bilayer interior or to the polar lipid/water interface. As another example, oligomerization is required for many activities such as pore formation. Peptides have been often classified according to a single characteristic mode of interaction with the bilayer, but over the years a more versatile picture has emerged. It appears that any single peptide can adopt several different alignments and/or oligomeric states in response to changes in the environment. For instance, many antimicrobial peptides adopt a surface-parallel alignment at low concentration, but they tilt obliquely into or even fully insert transmembrane into the bilayer above a critical peptide-to-lipid ratio, often in the form of oligomeric pores. Similar changes in peptide orientation or oligomeric state have been observed as a function of, e.g., temperature, lipid composition, pH, or induced by a synergistic partner peptide. Such transitions between peptide states can be regarded as the result of a re-adjustment in the balance between peptide-peptide and peptide-lipid interactions, as the environment conditions are changed. Though often studied in model membrane systems, such rich variety of peptide states is even more likely to occur in native biomembranes with their diverse compositions and physicochemical properties. The ability to undergo transitions between different states thus plays a fundamental role for the biological activities of membrane-active peptides.
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Affiliation(s)
- Stephan L Grage
- Karlsruhe Institute of Technology, Institute for Biological Interfaces (IBG-2), Institute of Organic Chemistry, Karlsruhe, Germany
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120
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Bhattacharjya S, Ramamoorthy A. Multifunctional host defense peptides: functional and mechanistic insights from NMR structures of potent antimicrobial peptides. FEBS J 2009; 276:6465-73. [DOI: 10.1111/j.1742-4658.2009.07357.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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121
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Structure, dynamics and mapping of membrane-binding residues of micelle-bound antimicrobial peptides by natural abundance (13)C NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:114-21. [PMID: 19682427 DOI: 10.1016/j.bbamem.2009.07.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 06/08/2009] [Accepted: 07/30/2009] [Indexed: 12/23/2022]
Abstract
Worldwide bacterial resistance to traditional antibiotics has drawn much research attention to naturally occurring antimicrobial peptides (AMPs) owing to their potential as alternative antimicrobials. Structural studies of AMPs are essential for an in-depth understanding of their activity, mechanism of action, and in guiding peptide design. Two-dimensional solution proton NMR spectroscopy has been the major tool. In this article, we describe the applications of natural abundance (13)C NMR spectroscopy that provides complementary information to 2D (1)H NMR. The correlation of (13)Calpha secondary shifts with both 3D structure and heteronuclear (15)N NOE values indicates that natural abundance carbon chemical shifts are useful probes for backbone structure and dynamics of membrane peptides. Using human LL-37-derived peptides (GF-17, KR-12, and RI-10), as well as amphibian antimicrobial and anticancer peptide aurein 1.2 and its analog LLAA, as models, we show that the cross peak intensity plots of 2D (1)H-(13)Calpha HSQC spectra versus residue number present a wave-like pattern (HSQC wave) where key hydrophobic residues of micelle-bound peptides are located in the troughs with weaker intensities, probably due to fast exchange between the free and bound forms. In all the cases, the identification of aromatic phenylalanines as a key membrane-binding residue is consistent with previous intermolecular Phe-lipid NOE observations. Furthermore, mutation of one of the key hydrophobic residues of KR-12 to Ala significantly reduced the antibacterial activity of the peptide mutants. These results illustrate that natural abundance heteronuclear-correlated NMR spectroscopy can be utilized to probe backbone structure and dynamics, and perhaps to map key membrane-binding residues of peptides in complex with micelles. (1)H-(13)Calpha HSQC wave, along with other NMR waves such as dipolar wave and chemical shift wave, offers novel insights into peptide-membrane interactions from different angles.
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