151
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Ahmad A, Azmi S, Srivastava RM, Srivastava S, Pandey BK, Saxena R, Bajpai VK, Ghosh JK. Design of nontoxic analogues of cathelicidin-derived bovine antimicrobial peptide BMAP-27: the role of leucine as well as phenylalanine zipper sequences in determining its toxicity. Biochemistry 2009; 48:10905-17. [PMID: 19845398 DOI: 10.1021/bi9009874] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BMAP-27 is a cathelicidin-derived bovine antimicrobial peptide, which shows moderate cytotoxicity and potent antibacterial activity against a wide variety of microorganisms. Despite a number of studies, very little is known about the amino acid sequences of this peptide that controls its antibacterial and cytotoxic activities. Small stretches of phenylalanine and leucine zipper sequences were identified at the N- and C-termini of the molecule, respectively. To understand the structural and functional roles of these sequence elements, we synthesized and characterized several analogues of BMAP-27 after substituting leucine or phenylalanine residue(s) at a and/or d positions of the leucine and phenylalanine zipper sequences, respectively, with alanine. BMAP-27 analogues exhibited significantly reduced cytotoxicity against the human red blood (hRBC) and murine 3T3 cells as compared to that of the wild-type peptide. Interestingly, BMAP-27 and its analogues exhibited comparable antibacterial activity against the selected Gram-positive and Gram-negative bacteria. Moreover, BMAP-27 and its analogues exhibited similar localization and assembly onto the selected bacteria and induced comparable permeability in these cells. However, only BMAP-27, not its analogues, assembled and bound strongly onto the hRBCs and permeabilized them. The results indicated that not only a leucine zipper but also a phenylalanine zipper sequence plays an important role in maintaining the assembly of BMAP-27 on the mammalian cells examined here and cytotoxic activity against them. To the best of our knowledge, this is the first report of the evaluation of structural and functional roles of a phenylalanine zipper sequence in a naturally occurring antimicrobial peptide.
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Affiliation(s)
- Aqeel Ahmad
- Molecular and Structural Biology Division, Central Drug Research Institute, CSIR,Lucknow 226001, India
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152
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Tarafdar PK, Vedantam LV, Kondreddy A, Podile AR, Swamy MJ. Biophysical investigations on the aggregation and thermal unfolding of harpinPss and identification of leucine-zipper-like motifs in harpins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1684-92. [DOI: 10.1016/j.bbapap.2009.07.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 07/11/2009] [Accepted: 07/31/2009] [Indexed: 11/17/2022]
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153
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Limbachiya MS, Pande AH. Peptide derived from the lipid binding domain of Group IB human pancreatic phospholipase A2 possesses antibacterial activity. Biochimie 2009; 91:1387-93. [DOI: 10.1016/j.biochi.2009.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 07/10/2009] [Indexed: 10/20/2022]
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154
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Manna M, Mukhopadhyay C. Cause and effect of melittin-induced pore formation: a computational approach. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:12235-12242. [PMID: 19754202 DOI: 10.1021/la902660q] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Melittin embedded in a palmitoyl oleyl phosphatidylcholine bilayer at a high peptide/lipid ratio (1:30) was simulated in the presence of explicit water and ions. The simulation results indicate the incipience of an ion-permeable water pore through collective membrane perturbation by bound peptides. The positively charged residues of melittin not only act as "anchors" but also disrupt the membrane, leading to cell lysis. A detailed analysis of the lipid tail order parameter profile depicts localized membrane perturbation. The lipids in the vicinity of the aqueous cavity adopt a tilted conformation, which allows local bilayer thinning. The prepore thus formed can be considered as the melittin-induced structural defects in the bilayer membrane. Because of the strong cationic nature, the melittin-induced prepore exhibits selectivity toward anions over cations. As Cl(-) ions entered into the prepore, they are electrostatically entrapped by positively charged residues located at its wall. The confined motion of the Cl(-) ions in the membrane interior is obvious from calculated diffusion coefficients. Moreover, reorientation of the local lipids occurs in such a way that few lipid heads along with peptide helices can line the surface of the penetrating aqueous phase. The flipping of lipids argued in favor of melittin-induced toroidal pore over a barrel-stave mechanism. Thus, our result provides atomistic level details of the mechanism of membrane disruption by antimicrobial peptide melittin.
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Affiliation(s)
- Moutusi Manna
- Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata-700 009, India
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155
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Olaru A, Gheorghiu M, David S, Wohland T, Gheorghiu E. Assessment of the Multiphase Interaction between a Membrane Disrupting Peptide and a Lipid Membrane. J Phys Chem B 2009; 113:14369-80. [DOI: 10.1021/jp905170u] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andreea Olaru
- International Centre of Biodynamics, Bucharest, Romania, and Department of Chemistry, National University of Singapore, Singapore
| | - Mihaela Gheorghiu
- International Centre of Biodynamics, Bucharest, Romania, and Department of Chemistry, National University of Singapore, Singapore
| | - Sorin David
- International Centre of Biodynamics, Bucharest, Romania, and Department of Chemistry, National University of Singapore, Singapore
| | - Thorsten Wohland
- International Centre of Biodynamics, Bucharest, Romania, and Department of Chemistry, National University of Singapore, Singapore
| | - Eugen Gheorghiu
- International Centre of Biodynamics, Bucharest, Romania, and Department of Chemistry, National University of Singapore, Singapore
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156
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Ahmad A, Asthana N, Azmi S, Srivastava RM, Pandey BK, Yadav V, Ghosh JK. Structure-function study of cathelicidin-derived bovine antimicrobial peptide BMAP-28: design of its cell-selective analogs by amino acid substitutions in the heptad repeat sequences. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2411-20. [PMID: 19735644 DOI: 10.1016/j.bbamem.2009.08.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 08/24/2009] [Accepted: 08/25/2009] [Indexed: 10/20/2022]
Abstract
Although BMAP-28 is a potent cathelicidin-derived bovine antimicrobial peptide, its cytotoxic activity against the human and other mammalian cells is of concern for converting it into a novel antimicrobial drug. We have identified a short leucine and isoleucine zipper sequences at the N- and C-terminals of BMAP-28, respectively. To understand the possible role of these structural elements in BMAP-28, a number of alanine-substituted analogs were designed, synthesized and characterized along with the wild-type peptide. The substitution of amino acids at single or multiple 'a' position(s) of these structural motifs by alanine showed significant effects on the cytotoxic activity of the molecule on the human red blood cells (hRBCs) and 3T3 cells without showing much effects on their MIC values against the selected bacteria. BMAP-28 and all its analogs depolarized the Escherichia coli cells with almost equal efficacy. In contrast, the alanine-substituted analogs of BMAP-28 depolarized hRBCs much less efficiently than the parent molecule. Results further showed that BMAP-28 assembled appreciably onto the live E. coli and hRBC. However, the selected less toxic analogs of BMAP-28 although assembled as good as the parent molecule onto the live E. coli cells, their assembly onto the live mammalian hRBCs was much weaker as compared to that of the wild-type molecule. Looking at the remarkable similarity with the data presented in our previous work on melittin, it appears that probably the heptad repeat sequence possesses a general role in maintaining the cytotoxicity of the antimicrobial peptides against the mammalian cells and assembly therein.
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Affiliation(s)
- Aqeel Ahmad
- Molecular and Structural Biology Division, Central Drug Research Institute, CSIR, Lucknow-226001, India
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157
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Ouellet M, Voyer N, Auger M. Membrane interactions and dynamics of a 21-mer cytotoxic peptide: a solid-state NMR study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:235-43. [PMID: 19703408 DOI: 10.1016/j.bbamem.2009.07.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 07/06/2009] [Accepted: 07/30/2009] [Indexed: 11/29/2022]
Abstract
We have investigated the membrane interactions and dynamics of a 21-mer cytotoxic model peptide that acts as an ion channel by solid-state NMR spectroscopy. To shed light on its mechanism of membrane perturbation, (31)P and (2)H NMR experiments were performed on 21-mer peptide-containing bicelles. (31)P NMR results indicate that the 21-mer peptide stabilizes the bicelle structure and orientation in the magnetic field and perturbs the lipid polar head group conformation. On the other hand, (2)H NMR spectra reveal that the 21-mer peptide orders the lipid acyl chains upon binding. (15)N NMR experiments performed in DMPC bilayers stacked between glass plates also reveal that the 21-mer peptide remains at the bilayer surface. (15)N NMR experiments in perpendicular DMPC bicelles indicate that the 21-mer peptide does not show a circular orientational distribution in the bicelle planar region. Finally, (13)C NMR experiments were used to study the 21-mer peptide dynamics in DMPC multilamellar vesicles. By analyzing the (13)CO spinning sidebands, the results show that the 21-mer peptide is immobilized upon membrane binding. In light of these results, we propose a model of membrane interaction for the 21-mer peptide where it lies at the bilayer surface and perturbs the lipid head group conformation.
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Affiliation(s)
- Marise Ouellet
- Département de Chimie, PROTEO (Regroupement Québécois de Recherche sur la Fonction, la Structure et l'Ingénierie des Protéines), CERMA (Centre de Recherche sur les Matériaux Avancés), Université Laval, Québec, Québec, Canada G1V 0A6
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158
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Gheorghiu M, Olaru A, Tar A, Polonschii C, Gheorghiu E. Sensing based on assessment of non-monotonous effect determined by target analyte: Case study on pore-forming compounds. Biosens Bioelectron 2009; 24:3517-23. [PMID: 19497729 DOI: 10.1016/j.bios.2009.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 04/24/2009] [Accepted: 05/07/2009] [Indexed: 10/20/2022]
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159
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Polyansky AA, Vassilevski AA, Volynsky PE, Vorontsova OV, Samsonova OV, Egorova NS, Krylov NA, Feofanov AV, Arseniev AS, Grishin EV, Efremov RG. N-terminal amphipathic helix as a trigger of hemolytic activity in antimicrobial peptides: A case study in latarcins. FEBS Lett 2009; 583:2425-8. [DOI: 10.1016/j.febslet.2009.06.044] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 05/27/2009] [Accepted: 06/24/2009] [Indexed: 01/29/2023]
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160
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Zhu WL, Shin SY. Antimicrobial and cytolytic activities and plausible mode of bactericidal action of the cell penetrating peptide penetratin and its lys-linked two-stranded peptide. Chem Biol Drug Des 2009; 73:209-15. [PMID: 19207423 DOI: 10.1111/j.1747-0285.2008.00769.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cell penetrating peptide, penetratin (RQIKIWFQNRRMKWKK-NH2) showed potent antimicrobial activity (MIC: 0.5-4 microM) without any cytotoxicity against mammalian cells. This study investigated the effect of linking together two peptide chains of penetratin on antimicrobial and cytolytic activities and plausible mode of bactericidal action. Two-stranded penetratin was prepared by a simultaneous solid-phase synthesis of the two strands of a single lysine residue attached to the solid support. Two-stranded penetratin markedly increased cytolytic activity against human erythrocytes and NIH-3T3 mouse fibroblast cells without a significant effect on antimicrobial activity. This finding suggested that penetratin is active as a monomer to bacterial cells but as an oligomer to mammalian cells. Circular dichroism analysis revealed that the alpha-helical content of the membrane-bound penetratin was unaffected by two-stranded Lys-linkage. Penetratin had very weak ability in the depolarization of membrane potential of intact Staphylococcus aureus cells and the fluorescent dye leakage of calcein-entrapped negatively charged bacterial membrane-mimicking vesicles. In contrast, two-stranded penetratin significantly caused membrane depolarization and dye leakage. These results suggest that the two-stranded penetratin induces a significant change in its mode of bactericidal action from the intracellular-target mechanism to the membrane-targeting mechanism.
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Affiliation(s)
- Wan Long Zhu
- Department of Bio-Materials, Graduate School, Research Center for Proteineous Materials and Department of Cellular & Molecular Medicine, School of Medicine, Chosun University, Gwangju 501-759, Korea
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161
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Abstract
The conventional notion that peptides are poor candidates for orally available drugs because of protease-sensitive peptide bonds, intrinsic hydrophilicity, and ionic charges contrasts with the diversity of antibiotic natural products with peptide-based frameworks that are synthesized and utilized by Nature. Several of these antibiotics, including penicillin and vancomycin, are employed to treat bacterial infections in humans and have been best-selling therapeutics for decades. Others might provide new platforms for the design of novel therapeutics to combat emerging antibiotic-resistant bacterial pathogens.
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Affiliation(s)
- Elizabeth M Nolan
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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162
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A peptide derived from the putative transmembrane domain in the tail region of E. coli toxin hemolysin E assembles in phospholipid membrane and exhibits lytic activity to human red blood cells: Plausible implications in the toxic activity of the protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:538-50. [DOI: 10.1016/j.bbamem.2008.11.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Revised: 11/06/2008] [Accepted: 11/19/2008] [Indexed: 11/21/2022]
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163
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Cerovský V, Hovorka O, Cvacka J, Voburka Z, Bednárová L, Borovicková L, Slaninová J, Fucík V. Melectin: a novel antimicrobial peptide from the venom of the cleptoparasitic bee Melecta albifrons. Chembiochem 2009; 9:2815-21. [PMID: 18942691 DOI: 10.1002/cbic.200800476] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A novel antimicrobial peptide designated melectin was isolated from the venom of the cleptoparasitic bee Melecta albifrons. Its primary sequence was established as H-Gly-Phe-Leu-Ser-Ile-Leu-Lys-Lys-Val-Leu-Pro-Lys-Val-Met-Ala-His-Met-Lys-NH(2) by Edman degradation and ESI-QTOF mass spectrometry. Synthetic melectin exhibited antimicrobial activity against both gram-positive and -negative bacteria and it degranulated rat peritoneal mast cells, but its hemolytic activity was low. The CD spectra of melectin measured in the presence of trifluoroethanol and sodium dodecyl sulfate showed a high content alpha-helices, which indicates that melectin can adopt an amphipathic alpha-helical secondary structure in an anisotropic environment such as the bacterial cell membrane. To envisage the role of the proline residue located in the middle of the peptide chain on biological activity and secondary structure, we prepared several melectin analogues in which the Pro11 residue was either replaced by other amino acid residues or was omitted. The results of biological testing suggest that a Pro kink in the alpha-helical structure of melectin plays an important role in selectivity for bacterial cells. In addition, a series of N- and C-terminal-shortened analogues was synthesized to examine which region of the peptide is related to antimicrobial activity.
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Affiliation(s)
- Václav Cerovský
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo 2, 166 10 Prague 6, Czech Republic.
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164
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Sengupta D, Leontiadou H, Mark AE, Marrink SJ. Toroidal pores formed by antimicrobial peptides show significant disorder. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2308-17. [DOI: 10.1016/j.bbamem.2008.06.007] [Citation(s) in RCA: 381] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 05/27/2008] [Accepted: 06/02/2008] [Indexed: 01/02/2023]
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165
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Parisien A, Allain B, Zhang J, Mandeville R, Lan CQ. Novel alternatives to antibiotics: bacteriophages, bacterial cell wall hydrolases, and antimicrobial peptides. J Appl Microbiol 2008; 104:1-13. [PMID: 18171378 DOI: 10.1111/j.1365-2672.2007.03498.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Extensive research has been conducted on the development of three groups of naturally occurring antimicrobials as novel alternatives to antibiotics: bacteriophages (phages), bacterial cell wall hydrolases (BCWH), and antimicrobial peptides (AMP). Phage therapies are highly efficient, highly specific, and relatively cost-effective. However, precautions have to be taken in the selection of phage candidates for therapeutic applications as some phages may encode toxins and others may, when integrated into host bacterial genome and converted to prophages in a lysogenic cycle, lead to bacterial immunity and altered virulence. BCWH are divided into three groups: lysozymes, autolysins, and virolysins. Among them, virolysins are the most promising candidates as they are highly specific and have the capability to rapidly lyse antibiotic-resistant bacteria on a generally species-specific basis. Finally, AMP are a family of natural proteins produced by eukaryotic and prokaryotic organisms or encoded by phages. AMP are of vast diversity in term of size, structure, mode of action, and specificity and have a high potential for clinical therapeutic applications.
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Affiliation(s)
- A Parisien
- Department of Chemical Engineering, University of Ottawa, Ottawa, Canada
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166
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Ivanovic T, Agosto MA, Zhang L, Chandran K, Harrison SC, Nibert ML. Peptides released from reovirus outer capsid form membrane pores that recruit virus particles. EMBO J 2008; 27:1289-98. [PMID: 18369316 DOI: 10.1038/emboj.2008.60] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 02/27/2008] [Indexed: 01/27/2023] Open
Abstract
Nonenveloped animal viruses must disrupt or perforate a cell membrane during entry. Recent work with reovirus has shown formation of size-selective pores in RBC membranes in concert with structural changes in capsid protein mu1. Here, we demonstrate that mu1 fragments released from reovirus particles are sufficient for pore formation. Both myristoylated N-terminal fragment mu1N and C-terminal fragment phi are released from particles. Both also associate with RBC membranes and contribute to pore formation in the absence of particles, but mu1N has the primary and sufficient role. Particles with a mutant form of mu1, unable to release mu1N or form pores, lack the ability to associate with membranes. They are, however, recruited by pores preformed with peptides released from wild-type particles or with synthetic mu1N. The results provide evidence that docking to membrane pores by virus particles may be a next step in membrane penetration after pore formation by released peptides.
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Affiliation(s)
- Tijana Ivanovic
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA, USA
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167
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Zhu WL, Nan YH, Hahm KS, Shin SY. Cell Selectivity of an Antimicrobial Peptide Melittin Diastereomer with D-amino Acid in the Leucine Zipper Sequence. BMB Rep 2007; 40:1090-4. [DOI: 10.5483/bmbrep.2007.40.6.1090] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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168
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Abstract
Melittin is the principal toxic component in the venom of the European honey bee Apis mellifera and is a cationic, hemolytic peptide. It is a small linear peptide composed of 26 amino acid residues in which the amino-terminal region is predominantly hydrophobic whereas the carboxy-terminal region is hydrophilic due to the presence of a stretch of positively charged amino acids. This amphiphilic property of melittin has resulted in melittin being used as a suitable model peptide for monitoring lipid-protein interactions in membranes. In this review, the solution and membrane properties of melittin are highlighted, with an emphasis on melittin-membrane interaction using biophysical approaches. The recent applications of melittin in various cellular processes are discussed.
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Affiliation(s)
- H Raghuraman
- Centre for Cellular and Molecular Biology, Hyderabad, India
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169
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Glukhov E, Shulga YV, Epand RF, Dicu AO, Topham MK, Deber CM, Epand RM. Membrane interactions of the hydrophobic segment of diacylglycerol kinase epsilon. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:2549-58. [PMID: 17669357 DOI: 10.1016/j.bbamem.2007.06.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 05/26/2007] [Accepted: 06/12/2007] [Indexed: 11/23/2022]
Abstract
Diacylglycerol kinase epsilon (DGKepsilon) is unique among mammalian DGK isoforms in having a segment of hydrophobic amino acids as a putative membrane anchor. To model the conformation, and stoichiometry of this segment in membrane-mimetic environments, we have prepared a peptide corresponding to this hydrophobic segment of DGKepsilon of sequence KKKKLILWTLCSVLLPVFITFWKKKKK-NH(2). Flanking Lys residues mimic the natural setting of this peptide in DGKepsilon, while facilitating peptide synthesis and characterization. Circular dichroism and fluorescence spectroscopic analysis demonstrated that the peptide has increased helical content and significant blue shifts in the presence of anionic--but not zwitterionic--bilayer membranes. When labeled with fluorophores that can undergo fluorescence resonance energy transfer, the peptide was found to dimerize--a result also observed from migration rates on SDS-PAGE gels under both reducing and non-reducing disulfide bridge conditions. The peptide was shown to preferentially interact with cholesterol in lipid films comprised of homogeneous mixtures of cholesterol and phosphatidylcholine, yet the presence of cholesterol in hydrated vesicle bilayers decreases its helical content. The peptide was also able to inhibit the activity of DGKepsilon protein in vitro. Our overall findings suggest that the peptide ultimately cannot leave the bulk water for attachment/insertion into the outer leaflet of an erythrocyte-like bilayer, yet its core sequence is sufficiently hydrophobic to insert into membrane core regions when membrane attachment is promoted by electrostatic attraction to anionic lipid head groups of the inner leaflet of an erythrocyte-like bilayer.
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Affiliation(s)
- Evgenia Glukhov
- Division of Molecular Structure & Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
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170
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Zhu WL, Song YM, Park Y, Park KH, Yang ST, Kim JI, Park IS, Hahm KS, Shin SY. Substitution of the leucine zipper sequence in melittin with peptoid residues affects self-association, cell selectivity, and mode of action. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1506-17. [PMID: 17462584 DOI: 10.1016/j.bbamem.2007.03.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Revised: 03/02/2007] [Accepted: 03/14/2007] [Indexed: 10/23/2022]
Abstract
Melittin (ME), a non-cell-selective antimicrobial peptide, contains the leucine zipper motif, wherein every seventh amino acid is leucine or isolucine. Here, we attempted to generate novel cell-selective peptides by substituting amino acids in the leucine zipper sequence of ME with peptoid residues. We generated a series of ME analogues by replacing Leu-6, Lue-13 and Ile-20 with Nala, Nleu, Nphe, or Nlys, and we examined their secondary structure, self-association activity, cell selectivity and mode of action. Circular dichroism spectroscopy indicated that the substitutions disrupt the alpha-helical structure of ME in micelles of sodium dodecyl sulfate and on negatively charged and zwitterionic phospholipid vesicles. Substitution by Nleu, Nphe, or Nlys but not Nala disturbed the self-association in an aqueous environment, interaction with zwitterionic membranes, and toxicity to mammalian cells of ME but did not affect the interaction with negatively charged membranes or antibacterial activity. Notably, peptides with Nphe or Nlys substitution had the highest therapeutic indices, consistent with their lipid selectivity. In addition, all of peptoid residue-containing ME analogues had little or no ability to induce membrane disruption, membrane depolarization and lipid flip-flop. Taken together, our studies indicate that substitution of the leucine zipper motif in ME with peptoid residues increases its selectivity against bacterial cells by impairing self-association activity and changes its mode of antibacterial action from membrane-targeting mechanism to possible intracellular targeting mechanism. Furthermore, our ME analogues especially those with Nleu, Nphe, or Nlys substitutions, may be therapeutically useful antimicrobial peptides.
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Affiliation(s)
- Wan Long Zhu
- Department of Bio-Materials, Graduate School and Research Center for Proteineous Materials, Chosun University, Gwangju 501-759, Korea
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171
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Lad MD, Birembaut F, Clifton LA, Frazier RA, Webster JRP, Green RJ. Antimicrobial peptide-lipid binding interactions and binding selectivity. Biophys J 2007; 92:3575-86. [PMID: 17325007 PMCID: PMC1853145 DOI: 10.1529/biophysj.106.097774] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 01/22/2007] [Indexed: 11/18/2022] Open
Abstract
Surface pressure measurements, external reflection-Fourier transform infrared spectroscopy, and neutron reflectivity have been used to investigate the lipid-binding behavior of three antimicrobial peptides: melittin, magainin II, and cecropin P1. As expected, all three cationic peptides were shown to interact more strongly with the anionic lipid, 1,2 dihexadecanoyl-sn-glycerol-3-(phosphor-rac-(1-glycerol)) (DPPG), compared to the zwitterionic lipid, 1,2 dihexadecanoyl-sn-glycerol-3-phosphocholine (DPPC). All three peptides have been shown to penetrate DPPC lipid layers by surface pressure, and this was confirmed for the melittin-DPPC interaction by neutron reflectivity measurements. Adsorption of peptide was, however, minimal, with a maximum of 0.4 mg m(-2) seen for melittin adsorption compared to 2.1 mg m(-2) for adsorption to DPPG (from 0.7 microM solution). The mode of binding to DPPG was shown to depend on the distribution of basic residues within the peptide alpha-helix, although in all cases adsorption below the lipid layer was shown to dominate over insertion within the layer. Melittin adsorption to DPPG altered the lipid layer structure observed through changes in the external reflection-Fourier transform infrared lipid spectra and neutron reflectivity. This lipid disruption was not observed for magainin or cecropin. In addition, melittin binding to both lipids was shown to be 50% greater than for either magainin or cecropin. Adsorption to the bare air-water interface was also investigated and surface activity followed the trend melittin>magainin>cecropin. External reflection-Fourier transform infrared amide spectra revealed that melittin adopted a helical structure only in the presence of lipid, whereas magainin and cecropin adopted helical structure also at an air-water interface. This behavior has been related to the different charge distributions on the peptide amino acid sequences.
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Affiliation(s)
- Mitaben D Lad
- School of Chemistry, Food Biosciences and Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, United Kingdom
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172
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Zhu WL, Lan H, Park IS, Kim JI, Jin HZ, Hahm KS, Shin SY. Design and mechanism of action of a novel bacteria-selective antimicrobial peptide from the cell-penetrating peptide Pep-1. Biochem Biophys Res Commun 2006; 349:769-74. [PMID: 16945333 DOI: 10.1016/j.bbrc.2006.08.094] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Accepted: 08/16/2006] [Indexed: 11/26/2022]
Abstract
Here, we report the successful design of a novel bacteria-selective antimicrobial peptide, Pep-1-K (KKTWWKTWWTKWSQPKKKRKV). Pep-1-K was designed by replacing Glu-2, Glu-6, and Glu-11 in the cell-penetrating peptide Pep-1 with Lys. Pep-1-K showed strong antibacterial activity against reference strains (MIC = 1-2 microM) of Gram-positive and Gram-negative bacteria as well as against clinical isolates (MIC = 1-8 microM) of methicillin-resistant Staphylococcus aureus and multidrug-resistant Pseudomonas aeruginosa. In contrast, Pep-1-K did not cause hemolysis of human erythrocytes even at 200 microM. These results indicate that Pep-1-K may be a good candidate for antimicrobial drug development, especially as a topical agent against antibiotic-resistant microorganisms. Tryptophan fluorescence studies indicated that the lack of hemolytic activity of Pep-1-K correlated with its weak ability to penetrate zwitterionic phosphatidylcholine/cholesterol (10:1, w/w) vesicles, which mimic eukaryotic membranes. Furthermore, Pep-1-K caused little or no dye leakage from negatively charged phosphatidylethanolamine/phosphatidylglycerol (7:3, w/w) vesicles, which mimic bacterial membranes but had a potent ability to cause depolarization of the cytoplasmic membrane potential of intact S. aureus cells. These results suggested that Pep-1-K kills microorganisms by not the membrane-disrupting mode but the formation of small channels that permit transit of ions or protons but not molecules as large as calcein.
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Affiliation(s)
- Wan Long Zhu
- Department of Bio-Materials, Graduate School and Research Center for Proteineous Materials, Chosun University, Gwangju 501-759, Republic of Korea
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173
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Ahmad A, Yadav SP, Asthana N, Mitra K, Srivastava SP, Ghosh JK. Utilization of an Amphipathic Leucine Zipper Sequence to Design Antibacterial Peptides with Simultaneous Modulation of Toxic Activity against Human Red Blood Cells. J Biol Chem 2006; 281:22029-22038. [PMID: 16717087 DOI: 10.1074/jbc.m602378200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The toxicity of naturally occurring or designed antimicrobial peptides is a major barrier for converting them into drugs. To synthesize antimicrobial peptides with reduced toxicity, several amphipathic peptides were designed based on the leucine zipper sequence. The first one was a leucine zipper peptide (LZP); in others, leucine residues at the a- and/or d-position were substituted with single or double alanine residues. The results showed that LZP and its analogs exhibited appreciable and similar antibacterial activity against the tested gram-positive and gram-negative bacteria. However, the substitution of alanine progressively lowered the toxicity of LZP against human red blood cells (hRBCs). The substitution of leucine with alanine impaired the binding and localization of LZP to hRBCs, but had little effect on the peptide-induced damage of Escherichia coli cells. Although LZP and its analogs exhibited similar permeability, secondary structures, and localization in negatively charged membranes, significant differences were observed among these peptides in zwitterionic membranes. The results suggest a novel approach for designing antibacterial peptides with modulation of toxicity against hRBCs by employing the leucine zipper sequence. Also, to the best of our knowledge, the results demonstrate that this sequence could be utilized to design novel cell-selective molecules for the first time.
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Affiliation(s)
- Aqeel Ahmad
- Molecular and Structural Biology Division, University of Oxford, Oxford OX3 7LD, United Kingdom
| | - Sharada Prasad Yadav
- Molecular and Structural Biology Division, University of Oxford, Oxford OX3 7LD, United Kingdom
| | - Neeta Asthana
- Molecular and Structural Biology Division, University of Oxford, Oxford OX3 7LD, United Kingdom
| | - Kalyan Mitra
- Electron Microscopy Unit, Central Drug Research Institute, Lucknow 226 001, India
| | | | - Jimut Kanti Ghosh
- Molecular and Structural Biology Division, University of Oxford, Oxford OX3 7LD, United Kingdom.
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174
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Gonçalves E, Kitas E, Seelig J. Structural and Thermodynamic Aspects of the Interaction between Heparan Sulfate and Analogues of Melittin. Biochemistry 2006; 45:3086-94. [PMID: 16503664 DOI: 10.1021/bi052221t] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Melittin is an amphipathic cationic peptide derived from honeybee venom with well-known cytolytic and antimicrobial properties. When coupled to cationic polymers or lipid molecules, it forms conjugates with high transfection efficiency and low toxicity with promising applications in gene therapy. A first step in the internalization of melittin and its conjugates is their binding to the cell surface, a reaction likely to involve heparan sulfate proteoglycans (HSPG). In the present work, we characterize the binding equilibrium of heparan sulfate (HS) with two melittin analogues, [Cys(1)]melittin (mel-SH) and retro-inverso [Cys(1)]melittin (ri-mel-SH). The terminal cysteine found in these peptides replaces the N-terminal glycine present in native melittin and allows covalent binding to other molecules. Isothermal titration calorimetry (ITC) reveals a high affinity of each melittin analogue to HS. Association constants of 4.7 x 10(4) and 3.5 x 10(5) M(-)(1) are found at physiological ionic strength and 15 degrees C for ri-mel-SH and mel-SH, respectively. The reaction enthalpy measured under these conditions is DeltaH(degrees)pep= 4.2 kcal/mol for ri-mel-SH and DeltaH(degrees)pep= 1.1 kcal/mol for mel-SH. The peptide-to-HS stoichiometry is approximately 20 for ri-mel-SH and approximately 14 for mel-SH under the same conditions. Temperature dependence studies using ri-mel-SH (mel-SH) show that DeltaH(degrees)pep decreases in magnitude upon increase in temperature, which results in a molar heat capacity of DeltaH(degrees)pep= -322 cal mol(-)(1) K(-)(1) (-45 cal mol(-)(1) K(-)(1)). Such a negative heat capacity change is not expected for a purely electrostatic interaction and indicates that hydrophobic and other interactions are also involved in the binding equilibrium. Salt dependence studies of the binding constants confirm that nonelectrostatic forces are an important component of the HS-melittin interaction. Binding to HS induces conformational changes in both peptides, with ri-mel-SH showing a 6-fold increase of the alpha-helix content when incubated with HS under saturation conditions.
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Affiliation(s)
- Elisabete Gonçalves
- Division of Biophysical Chemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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