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Chiroptical Properties and Conformation of Four Lasiocepsin-Related Antimicrobial Peptides: Structural Role of Disulfide Bridges. Symmetry (Basel) 2020. [DOI: 10.3390/sym12050812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We report an investigation of the role of disulfide bridges in the 27-residue antimicrobial peptide lasiocepsin (I) containing two disulfide groups (Cys8–Cys25, Cys17–Cys27) and three its analogs lacking one (II, III) or both (IV) native disulfides. Selective alternate incorporation of one or both disulfide bridges influences symmetry, conformation and biological properties of these peptides as demonstrated in their chiroptical (particularly Raman) properties. The effect of modifying the disulfide bridge pattern on the peptide secondary structure is investigated in water and in the presence of 2,2,2-trifluoroethanol and sodium dodecyl sulphate. A combination of experimental electronic and vibrational chiroptical data shows that both disulfide groups are necessary for stabilizing lasiocepsin secondary structure. While the Cys8–Cys25 disulfide group is important for sustaining lasiocepsin tertiary structure and maintaining its biological activity, the Cys17–Cys27 disulfide bridge has a supporting function consisting in reducing peptide flexibility.
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Interaction of Halictine-Related Antimicrobial Peptides with Membrane Models. Int J Mol Sci 2019; 20:ijms20030631. [PMID: 30717183 PMCID: PMC6387077 DOI: 10.3390/ijms20030631] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/24/2019] [Accepted: 01/28/2019] [Indexed: 01/19/2023] Open
Abstract
We have investigated structural changes of peptides related to antimicrobial peptide Halictine-1 (HAL-1) induced by interaction with various membrane-mimicking models with the aim to identify a mechanism of the peptide mode of action and to find a correlation between changes of primary/secondary structure and biological activity. Modifications in the HAL-1 amino acid sequence at particular positions, causing an increase of amphipathicity (Arg/Lys exchange), restricted mobility (insertion of Pro) and consequent changes in antimicrobial and hemolytic activity, led to different behavior towards model membranes. Secondary structure changes induced by peptide-membrane interaction were studied by circular dichroism, infrared spectroscopy, and fluorescence spectroscopy. The experimental results were complemented by molecular dynamics calculations. An α-helical structure has been found to be necessary but not completely sufficient for the HAL-1 peptides antimicrobial action. The role of alternative conformations (such as β-sheet, PPII or 310-helix) also seems to be important. A mechanism of the peptide mode of action probably involves formation of peptide assemblies (possibly membrane pores), which disrupt bacterial membrane and, consequently, allow membrane penetration.
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3
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Abstract
Many molecular features contribute to the antimicrobial activity of peptides. One aspect that contributes to the antimicrobial activity of a peptide, in many cases, results from the fact that many antimicrobial peptides are polycationic and the lipids on the surface of bacteria are often anionic. In certain cases this can result in the clustering of anionic lipids as a result of the binding of the cationic peptide to the surface of the bacterial membrane. This lipid clustering can be detrimental to the viability of the bacteria to which the peptide binds. Several factors, including the charge, size, and conformational flexibility of the peptide, will determine the efficiency of lipid clustering. In addition, the lipid composition of the bacterial membrane is very variable, and it plays a critical role in this mechanism. As a result, one can test the importance of this factor by determining the species specificity of the antimicrobial activity of the peptide. The molecular mechanism by which lipid clustering affects bacterial viability is uncertain in many cases. This phenomenon can be used to increase the antimicrobial potency of peptides in some case and can also predict the bacterial species specificity of some agents.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada.
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4
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Molchanova N, Hansen PR, Franzyk H. Advances in Development of Antimicrobial Peptidomimetics as Potential Drugs. Molecules 2017; 22:E1430. [PMID: 28850098 PMCID: PMC6151827 DOI: 10.3390/molecules22091430] [Citation(s) in RCA: 179] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 08/18/2017] [Accepted: 08/22/2017] [Indexed: 01/19/2023] Open
Abstract
The rapid emergence of multidrug-resistant pathogens has evolved into a global health problem as current treatment options are failing for infections caused by pan-resistant bacteria. Hence, novel antibiotics are in high demand, and for this reason antimicrobial peptides (AMPs) have attracted considerable interest, since they often show broad-spectrum activity, fast killing and high cell selectivity. However, the therapeutic potential of natural AMPs is limited by their short plasma half-life. Antimicrobial peptidomimetics mimic the structure and biological activity of AMPs, but display extended stability in the presence of biological matrices. In the present review, focus is on the developments reported in the last decade with respect to their design, synthesis, antimicrobial activity, cytotoxic side effects as well as their potential applications as anti-infective agents. Specifically, only peptidomimetics with a modular structure of residues connected via amide linkages will be discussed. These comprise the classes of α-peptoids (N-alkylated glycine oligomers), β-peptoids (N-alkylated β-alanine oligomers), β³-peptides, α/β³-peptides, α-peptide/β-peptoid hybrids, α/γ N-acylated N-aminoethylpeptides (AApeptides), and oligoacyllysines (OAKs). Such peptidomimetics are of particular interest due to their potent antimicrobial activity, versatile design, and convenient optimization via assembly by standard solid-phase procedures.
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Affiliation(s)
- Natalia Molchanova
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 162, DK-2100 Copenhagen, Denmark.
| | - Paul R Hansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 162, DK-2100 Copenhagen, Denmark.
| | - Henrik Franzyk
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 162, DK-2100 Copenhagen, Denmark.
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5
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Dispersion and stabilization of cochleate nanoparticles. Eur J Pharm Biopharm 2017; 117:270-275. [DOI: 10.1016/j.ejpb.2017.04.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/28/2017] [Accepted: 04/27/2017] [Indexed: 11/19/2022]
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6
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Antimicrobial peptide cWFW kills by combining lipid phase separation with autolysis. Sci Rep 2017; 7:44332. [PMID: 28276520 PMCID: PMC5343580 DOI: 10.1038/srep44332] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 02/07/2017] [Indexed: 12/17/2022] Open
Abstract
The synthetic cyclic hexapeptide cWFW (cyclo(RRRWFW)) has a rapid bactericidal activity against both Gram-positive and Gram-negative bacteria. Its detailed mode of action has, however, remained elusive. In contrast to most antimicrobial peptides, cWFW neither permeabilizes the membrane nor translocates to the cytoplasm. Using a combination of proteome analysis, fluorescence microscopy, and membrane analysis we show that cWFW instead triggers a rapid reduction of membrane fluidity both in live Bacillus subtilis cells and in model membranes. This immediate activity is accompanied by formation of distinct membrane domains which differ in local membrane fluidity, and which severely disrupts membrane protein organisation by segregating peripheral and integral proteins into domains of different rigidity. These major membrane disturbances cause specific inhibition of cell wall synthesis, and trigger autolysis. This novel antibacterial mode of action holds a low risk to induce bacterial resistance, and provides valuable information for the design of new synthetic antimicrobial peptides.
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7
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The importance of cyclic structure for Labaditin on its antimicrobial activity against Staphylococcus aureus. Colloids Surf B Biointerfaces 2016; 148:453-459. [PMID: 27665378 DOI: 10.1016/j.colsurfb.2016.09.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 09/04/2016] [Accepted: 09/11/2016] [Indexed: 01/24/2023]
Abstract
Antimicrobial resistance has reached alarming levels in many countries, thus leading to a search for new classes of antibiotics, such as antimicrobial peptides whose activity is exerted by interacting specifically with the microorganism membrane. In this study, we investigate the molecular-level mechanism of action for Labaditin (Lo), a 10-amino acid residue cyclic peptide from Jatropha multifida with known bactericidal activity against Streptococcus mutans. We show that Lo is also effective against Staphylococcus aureus (S. aureus) but this does not apply to its linear analogue (L1). Using polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), we observed with that the secondary structure of Lo was preserved upon interacting with Langmuir monolayers from a phospholipid mixture mimicking S. aureus membrane, in contrast to L1. This structure preservation for the rigid, cyclic Lo is key for the self-assembly of peptide nanotubes that induce pore formation in large unilamellar vesicles (LUVs), according to permeability assays and dynamic light scattering measurements. In summary, the comparison between Labaditin (Lo) and its linear analogue L1 allowed us to infer that the bactericidal activity of Lo is more related to its interaction with the membrane. It does not require specific metabolic targets, which makes cyclic peptides promising for antibiotics without bacteria resistance.
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Zhang N, Jovanovic G, McDonald C, Ces O, Zhang X, Buck M. Transcription Regulation and Membrane Stress Management in Enterobacterial Pathogens. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 915:207-30. [DOI: 10.1007/978-3-319-32189-9_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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9
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Hollander A, Danino D. Cochleate characterization by cryogenic electron microscopy methods: Cryo-TEM and Cryo-SEM. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.07.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Hovakeemian SG, Liu R, Gellman SH, Heerklotz H. Correlating antimicrobial activity and model membrane leakage induced by nylon-3 polymers and detergents. SOFT MATTER 2015; 11:6840-51. [PMID: 26234884 PMCID: PMC4666704 DOI: 10.1039/c5sm01521a] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Most antimicrobial peptides act upon target microorganisms by permeabilizing their membranes. The mode of action is often assessed by vesicle leakage experiments that use model membranes, with the assumption that biological activity correlates with the permeabilization of the lipid bilayer. The current work aims to extend the interpretation of vesicle leakage results and examine the correlation between vesicle leakage and antimicrobial activity. To this end, we used a lifetime-based leakage assay with calcein-loaded vesicles to study the membrane permeabilizing properties of a novel antifungal polymer poly-NM, two of its analogs, and a series of detergents. In conjunction, the biological activities of these compounds against Candida albicans were assessed and correlated with data from vesicle leakage. Poly-NM induces all-or-none leakage in polar yeast lipid vesicles at the polymer's MIC, 3 μg mL(-1). At this and higher concentrations, complete leakage after an initial lag time was observed. Concerted activity tests imply that this polymer acts independently of the detergent octyl glucoside (OG) for both vesicle leakage and activity against C. albicans spheroplasts. In addition, poly-NM was found to have negligible activity against zwitterionic vesicles and red blood cells. Our results provide a consistent, detailed picture of the mode of action of poly-NM: this polymer induces membrane leakage by electrostatic lipid clustering. In contrast, poly-MM:CO, a nylon-3 polymer comprised of both cationic and hydrophobic segments, seems to act by a different mechanism that involves membrane asymmetry stress. Vesicle leakage for this polymer is transient (limited to <100%) and graded, non-specific among zwitterionic and polar yeast lipid vesicles, additive with detergent action, and correlates poorly with biological activity. Based on these results, we conclude that comprehensive leakage experiments can provide a detailed description of the mode of action of membrane permeabilizing compounds. Without this thorough approach, it would have been logical to assume that the two nylon-3 polymers we examined act via similar mechanisms; it is surprising that their mechanisms are so distinct. Some, but not all mechanisms of vesicle permeabilization allow for antimicrobial activity.
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Vila-Farrés X, López-Rojas R, Pachón-Ibáñez ME, Teixidó M, Pachón J, Vila J, Giralt E. Sequence-activity relationship, and mechanism of action of mastoparan analogues against extended-drug resistant Acinetobacter baumannii. Eur J Med Chem 2015; 101:34-40. [PMID: 26114809 DOI: 10.1016/j.ejmech.2015.06.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 06/04/2015] [Accepted: 06/07/2015] [Indexed: 10/23/2022]
Abstract
The treatment of some infectious diseases can currently be very challenging since the spread of multi-, extended- or pan-resistant bacteria has considerably increased over time. On the other hand, the number of new antibiotics approved by the FDA has decreased drastically over the last 30 years. The main objective of this study was to investigate the activity of wasp peptides, specifically mastoparan and some of its derivatives against extended-resistant Acinetobacter baumannii. We optimized the stability of mastoparan in human serum since the specie obtained after the action of the enzymes present in human serum is not active. Thus, 10 derivatives of mastoparan were synthetized. Mastoparan analogues (guanidilated at the N-terminal, enantiomeric version and mastoparan with an extra positive charge at the C-terminal) showed the same activity against Acinetobacter baumannii as the original peptide (2.7 μM) and maintained their stability to more than 24 h in the presence of human serum compared to the original compound. The mechanism of action of all the peptides was carried out using a leakage assay. It was shown that mastoparan and the abovementioned analogues were those that released more carboxyfluorescein. In addition, the effect of mastoparan and its enantiomer against A. baumannii was studied using transmission electron microscopy (TEM). These results suggested that several analogues of mastoparan could be good candidates in the battle against highly resistant A. baumannii infections since they showed good activity and high stability.
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Affiliation(s)
- Xavier Vila-Farrés
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Rafael López-Rojas
- Biomedical Institute of Seville (IBiS), University Hospital Virgen del Rocío/CSIC/University of Seville, Seville, Spain
| | - Maria Eugenia Pachón-Ibáñez
- Biomedical Institute of Seville (IBiS), University Hospital Virgen del Rocío/CSIC/University of Seville, Seville, Spain
| | - Meritxell Teixidó
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
| | - Jerónimo Pachón
- Biomedical Institute of Seville (IBiS), University Hospital Virgen del Rocío/CSIC/University of Seville, Seville, Spain
| | - Jordi Vila
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain; Department of Clinical Microbiology, CDB, Hospital Clinic, School of Medicine, University of Barcelona, Barcelona, Spain.
| | - Ernest Giralt
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain; Department of Organic Chemistry, University of Barcelona, Barcelona, Spain.
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12
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Bozó T, Brecska R, Gróf P, Kellermayer MSZ. Extreme resilience in cochleate nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:839-845. [PMID: 25521248 DOI: 10.1021/la504428x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Cochleates, prospective nanoscale drug delivery vehicles, are rolls of negatively charged phospholipid membrane layers. The membrane layers are held together by calcium ions; however, neither the magnitude of membrane interaction forces nor the overall mechanical properties of cochleates have been known. Here, we manipulated individual nanoparticles with atomic force microscopy to characterize their nanomechanical behavior. Their stiffness (4.2-12.5 N/m) and membrane-rupture forces (45.3-278 nN) are orders of magnitude greater than those of the tough viral nanoshells. Even though the fundamental building material of cochleates is a fluid membrane, the combination of supramolecular geometry, the cross-linking action of calcium, and the tight packing of the ions apparently lead to extreme mechanical resilience. The supramolecular design of cochleates may provide efficient protection for encapsulated materials and give clues to understanding biomolecular structures of similar design, such as the myelinated axon.
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Affiliation(s)
- Tamás Bozó
- Department of Biophysics and Radiation Biology, and ‡MTA-SE Molecular Biophysics Research Group, Semmelweis University , Tűzoltó utca 37-47, Budapest 1094, Hungary
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13
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Dan N. Lipid-Nucleic Acid Supramolecular Complexes: Lipoplex Structure and the Kinetics of Formation. AIMS BIOPHYSICS 2015. [DOI: 10.3934/biophy.2015.2.163] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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14
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Patel H, Huynh Q, Bärlehner D, Heerklotz H. Additive and synergistic membrane permeabilization by antimicrobial (lipo)peptides and detergents. Biophys J 2014; 106:2115-25. [PMID: 24853740 DOI: 10.1016/j.bpj.2014.04.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 03/10/2014] [Accepted: 04/01/2014] [Indexed: 12/27/2022] Open
Abstract
Certain antibiotic peptides are thought to permeabilize membranes of pathogens by effects that are also observed for simple detergents, such as membrane thinning and disordering, asymmetric bilayer expansion, toroidal pore formation, and micellization. Here we test the hypothesis that such peptides act additively with detergents when applied in parallel. Additivity is defined analogously to a fractional inhibitory concentration index of unity, and the extent and mechanism of leakage is measured by the fluorescence lifetime-based vesicle leakage assay using calcein-loaded vesicles. Good additivity was found for the concerted action of magainin 2, the fungicidal lipopeptide class of surfactins from Bacillus subtilis QST713, and the detergent octyl glucoside, respectively, with the detergent C12EO8. Synergistic or superadditive action was observed for fengycins from B. subtilis, as well as the detergent CHAPS, when combined with C12EO8. The results illustrate two mechanisms of synergistic action: First, maximal leakage requires an optimum degree of heterogeneity in the system that may be achieved by mixing a graded with an all-or-none permeabilizer. (The optimal perturbation should be focused to certain defect structures, yet not to the extent that some vesicles are not affected at all.) Second, a cosurfactant may enhance the bioavailability of a poorly soluble peptide. The results are important for understanding the concerted action of membrane-permeabilizing compounds in biology as well as for optimizing formulations of such antimicrobials for medical applications or crop protection.
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Affiliation(s)
- Hiren Patel
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada; Department of Biophysics and Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Quang Huynh
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Dominik Bärlehner
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Heiko Heerklotz
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada; Institut für Medizinische Physik und Biophysik, Universität Leipzig, Leipzig, Germany.
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15
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Carmona-Ribeiro AM, de Melo Carrasco LD. Novel formulations for antimicrobial peptides. Int J Mol Sci 2014; 15:18040-83. [PMID: 25302615 PMCID: PMC4227203 DOI: 10.3390/ijms151018040] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 08/30/2014] [Accepted: 09/16/2014] [Indexed: 12/22/2022] Open
Abstract
Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy.
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Affiliation(s)
- Ana Maria Carmona-Ribeiro
- Biocolloids Laboratory, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil.
| | - Letícia Dias de Melo Carrasco
- Biocolloids Laboratory, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000 São Paulo, SP, Brazil.
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16
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Amphiphilic macromolecules on cell membranes: from protective layers to controlled permeabilization. J Membr Biol 2014; 247:861-81. [PMID: 24903487 DOI: 10.1007/s00232-014-9679-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 05/09/2014] [Indexed: 12/13/2022]
Abstract
Antimicrobial and cell-penetrating peptides have inspired developments of abiotic membrane-active polymers that can coat, penetrate, or break lipid bilayers in model systems. Application to cell cultures is more recent, but remarkable bioactivities are already reported. Synthetic polymer chains were tailored to achieve (i) high biocide efficiencies, and selectivity for bacteria (Gram-positive/Gram-negative or bacterial/mammalian membranes), (ii) stable and mild encapsulation of viable isolated cells to escape immune systems, (iii) pH-, temperature-, or light-triggered interaction with cells. This review illustrates these recent achievements highlighting the use of abiotic polymers, and compares the major structural determinants that control efficiency of polymers and peptides. Charge density, sp. of cationic and guanidinium side groups, and hydrophobicity (including polarity of stimuli-responsive moieties) guide the design of new copolymers for the handling of cell membranes. While polycationic chains are generally used as biocidal or hemolytic agents, anionic amphiphilic polymers, including Amphipols, are particularly prone to mild permeabilization and/or intracell delivery.
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17
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Qin X, Xie W, Tian S, Ali MA, Shirke A, Gross RA. Influence of Nε-Protecting Groups on the Protease-Catalyzed Oligomerization of l-Lysine Methyl Ester. ACS Catal 2014. [DOI: 10.1021/cs500268d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Xu Qin
- Rensselaer Polytechnic Institute (RPI), Department of Chemistry and Biology,
Center for Biotechnology and Interdisciplinary Studies, 4005B BioTechnology Bldg., 110 Eighth
Street, Troy, New York 12180, United States
| | - Wenchun Xie
- Rensselaer Polytechnic Institute (RPI), Department of Chemistry and Biology,
Center for Biotechnology and Interdisciplinary Studies, 4005B BioTechnology Bldg., 110 Eighth
Street, Troy, New York 12180, United States
| | - Sai Tian
- Rensselaer Polytechnic Institute (RPI), Department of Chemistry and Biology,
Center for Biotechnology and Interdisciplinary Studies, 4005B BioTechnology Bldg., 110 Eighth
Street, Troy, New York 12180, United States
| | - Mohamed Abo Ali
- Rensselaer Polytechnic Institute (RPI), Department of Chemistry and Biology,
Center for Biotechnology and Interdisciplinary Studies, 4005B BioTechnology Bldg., 110 Eighth
Street, Troy, New York 12180, United States
| | - Abhijeet Shirke
- Rensselaer Polytechnic Institute (RPI), Department of Chemistry and Biology,
Center for Biotechnology and Interdisciplinary Studies, 4005B BioTechnology Bldg., 110 Eighth
Street, Troy, New York 12180, United States
| | - Richard A. Gross
- Rensselaer Polytechnic Institute (RPI), Department of Chemistry and Biology,
Center for Biotechnology and Interdisciplinary Studies, 4005B BioTechnology Bldg., 110 Eighth
Street, Troy, New York 12180, United States
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18
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Dan N, Danino D. Structure and kinetics of lipid-nucleic acid complexes. Adv Colloid Interface Sci 2014; 205:230-9. [PMID: 24529969 DOI: 10.1016/j.cis.2014.01.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 01/13/2014] [Accepted: 01/13/2014] [Indexed: 01/08/2023]
Abstract
The structure and function of lipid-based complexes (lipoplexes) have been widely investigated as cellular delivery vehicles for nucleic acids-DNA and siRNA. Transfection efficiency in applications such as gene therapy and gene silencing has been clearly linked to the local, nano-scale organization of the nucleic acid in the vehicle, as well as to the global properties (e.g. size) of the carriers. This review focuses on both the structure of DNA and siRNA complexes with cationic lipids, and the kinetics of structure evolution during complex formation. The local organization of the lipoplexes is largely set by thermodynamic, equilibrium forces, dominated by the lipid preferred phase. As a result, complexation of linear lambda-phage DNA, circular plasmid DNA, or siRNA with lamellae-favoring lipids (or lipid mixtures) forms multi-lamellar L(α)(C) liquid crystalline arrays. Complexes created with lipids that have bulky tail groups may form inverted hexagonal HII(C) phases, or bicontinuous cubic Q(II)(C) phases. The kinetics of complex formation dominates the large-scale, global structure and the properties of lipoplexes. Furthermore, the time-scales required for the evolution of the equilibrium structure may be much longer than expected. In general, the process may be divided into three distinct stages: An initial binding, or adsorption step, where the nucleic acid binds onto the surface of the cationic vesicles. This step is relatively rapid, occurring on time scales of order of milliseconds, and largely insensitive to system parameters. In the second step, vesicles carrying adsorbed nucleic acid aggregate to form larger complexes. This step is sensitive to the lipid characteristics, in particular the bilayer rigidity and propensity to rupture, and to the lipid to nucleic acid (L/D) charge ratio, and is characterized by time scales of order seconds. The last and final step is that of internal rearrangement, where the overall global structure remains constant while local adjustment of the nucleic acid/lipid organization takes place. This step may occur on unusually long time scales of order hours or longer. This rate, as well, is highly sensitive to lipid characteristics, including membrane fluidity and rigidity. While the three step process is consistent with many experimental observations to date, improving the performance of these non-viral vectors requires better understanding of the correlations between the parameters that influence lipoplexes' formation and stability and the specific rate constants i.e., the timescales required to obtain the equilibrium structures. Moreover, new types of cellular delivery agents are now emerging, such as antimicrobial peptide complexes with anionic lipids, and other proteins and small-molecule lipid carriers, suggesting that better understanding of lipoplex kinetics would apply to a variety of new systems in biotechnology and nanomedicine.
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High-quality 3D structures shine light on antibacterial, anti-biofilm and antiviral activities of human cathelicidin LL-37 and its fragments. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2160-72. [PMID: 24463069 DOI: 10.1016/j.bbamem.2014.01.016] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/26/2013] [Accepted: 01/10/2014] [Indexed: 01/07/2023]
Abstract
Host defense antimicrobial peptides are key components of human innate immunity that plays an indispensible role in human health. While there are multiple copies of cathelicidin genes in horses, cattle, pigs, and sheep, only one cathelicidin gene is found in humans. Interestingly, this single cathelicidin gene can be processed into different forms of antimicrobial peptides. LL-37, the most commonly studied form, is not only antimicrobial but also possesses other functional roles such as chemotaxis, apoptosis, wound healing, immune modulation, and cancer metastasis. This article reviews recent advances made in structural and biophysical studies of human LL-37 and its fragments, which serve as a basis to understand their antibacterial, anti-biofilm and antiviral activities. High-quality structures were made possible by using improved 2D NMR methods for peptide fragments and 3D NMR spectroscopy for intact LL-37. The two hydrophobic domains in the long amphipathic helix (residues 2-31) of LL-37 separated by a hydrophilic residue serine 9 explain its cooperative binding to bacterial lipopolysaccharides (LPS). Both aromatic rings (F5, F6, F17, and F27) and interfacial basic amino acids of LL-37 directly interact with anionic phosphatidylglycerols (PG). Although the peptide sequences reported in the literature vary slightly, there is a consensus that the central helix of LL-37 is essential for disrupting superbugs (e.g., MRSA), bacterial biofilms, and viruses such as human immunodeficiency virus 1 (HIV-1) and respiratory syncytial virus (RSV). In the central helix, the central arginine R23 is of particular importance in binding to bacterial membranes or DNA. Mapping the functional roles of the cationic amino acids of the major antimicrobial region of LL-37 provides a basis for designing antimicrobial peptides with desired properties. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.
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Goldberg K, Sarig H, Zaknoon F, Epand RF, Epand RM, Mor A. Sensitization of gram-negative bacteria by targeting the membrane potential. FASEB J 2013; 27:3818-26. [PMID: 23733749 DOI: 10.1096/fj.13-227942] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Toward generating new tools for fighting multidrug-resistant (MDR) bacteria, we assessed the ability of a membrane-active peptide to sensitize gram-negative bacteria to various antibiotics. The mechanism for affecting inner and/or outer membrane functions was assessed by complementary biophysical methods (SPR, DSC, ITC). The implication of efflux pumps was examined using Acr-AB mutants, as tested with representative antibiotics, host defense peptides, and synthetic mimics. The ability to affect disease course systemically was compared for a single therapy and combination therapy, using the mouse thigh-infection model. The data show that potent antibiotic action can be provoked in vitro and in vivo, by a treatment combining two antibacterial compounds whose individual inefficiency against gram-negative bacteria stems from their efflux. Thus, at subminimal inhibitory concentrations, the lipopeptide-like sequence, N(α)(ω7)dodecenoyl-lysyl-[lysyl-aminododecanoyl-lysyl]-amide (designated C12(ω7)K-β12), has, nonetheless, rapidly achieved a transient membrane depolarization, which deprived bacteria of the proton-motive force required for active efflux. Consequently, bacteria became significantly sensitive to intracellular targeting antibiotics. Collectively, these findings suggest a potentially useful approach for expanding the antibiotics sensitivity spectrum of MDR gram-negative bacteria to include efflux substrates.
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Affiliation(s)
- Keren Goldberg
- Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel
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Rishi P, Singh AP, Arora S, Garg N, Kaur IP. Revisiting eukaryotic anti-infective biotherapeutics. Crit Rev Microbiol 2013; 40:281-92. [PMID: 23317462 DOI: 10.3109/1040841x.2012.749210] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Emerging drug resistance has forced the scientific community to revisit the observational data documented in the folklore and come up with novel and effective alternatives. Candidates from eukaryotic origin including herbal products and antimicrobial peptides are finding a strategic place in the therapeutic armamentarium against infectious diseases. These agents have recently gained interest owing to their versatile applications. Present review encompasses the use of these alternative strategies in their native or designer form, alone or in conjunction with antibiotics, as possible remedial measures. Further to this, the limitations or the possible concerns associated with these options are also discussed at length.
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Affiliation(s)
- Praveen Rishi
- Department of Microbiology, Panjab University , Chandigarh, Chandigarh , India and
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Mishra B, Epand RF, Epand RM, Wang G. Structural location determines functional roles of the basic amino acids of KR-12, the smallest antimicrobial peptide from human cathelicidin LL-37. RSC Adv 2013. [PMID: 24307932 DOI: 10.1039/c3ra42599a] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cationic antimicrobial peptides are recognized templates for developing a new generation of antimicrobials to combat superbugs. Human cathelicidin LL-37 is an essential host defense molecule in human innate immunity. Previously, we identified KR-12 as the smallest antibacterial peptide of LL-37. KR-12 has a narrow activity spectrum since it is active against Gram-negative Escherichia coli but not Gram-positive Staphylococcus aureus. The functional roles of the basic amino acids of KR-12, however, have not yet been elucidated. An alanine scan of cationic amino acids of KR-12 provided evidence for their distinct roles in the activities of the peptides. Bacterial killing and membrane permeation experiments indicate that the R23A and K25A mutants, as well as the lysine-to-arginine mutant, were more potent than KR-12. Another three cationic residues (K18, R19, and R29) of KR-12, which are located in the hydrophilic face of the amphiphathic helix, appeared to be more important in clustering anionic lipids or hemolysis than R23 and K25 in the interfacial region. While the loss of interfacial R23 or K25 reduced peptide helicity, underscoring its important role in membrane binding, the overall increase in peptide activity of KR-12 could be ascribed to the increased peptide hydrophobicity that outweighed the role of basic charge in this case. In contrast, the mutations of interfacial R23 or K25 reduced peptide bactericidal activity of GF-17, an overlapping, more hydrophobic and potent peptide also derived from LL-37. Thus, the hydrophobic context of the peptide determines whether an alanine substitution of an interfacial basic residue increases or decreases membrane permeation and peptide activity.
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Affiliation(s)
- Biswajit Mishra
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - Raquel F Epand
- Biochemistry and Biomedical Sciences, McMaster University Health Sciences Centre, Hamilton, Ontario, L8S 4K1, Canada
| | - Richard M Epand
- Biochemistry and Biomedical Sciences, McMaster University Health Sciences Centre, Hamilton, Ontario, L8S 4K1, Canada
| | - Guangshun Wang
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
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Pulido D, Nogués MV, Boix E, Torrent M. Lipopolysaccharide neutralization by antimicrobial peptides: a gambit in the innate host defense strategy. J Innate Immun 2012; 4:327-36. [PMID: 22441679 DOI: 10.1159/000336713] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 01/20/2012] [Indexed: 01/08/2023] Open
Abstract
Antimicrobial peptides (AMPs) are nowadays understood as broad multifunctional tools of the innate immune system to fight microbial infections. In addition to its direct antimicrobial action, AMPs can modulate the host immune response by promoting or restraining the recruitment of cells and chemicals to the infection focus. Binding of AMPs to lipopolysaccharide is a critical step for both their antimicrobial action and their immunomodulatory properties. On the one hand, removal of Gram-negative bacteria by AMPs can be an effective strategy to prevent a worsened inflammatory response that may lead to septic shock. On the other hand, by neutralizing circulating endotoxins, AMPs can successfully reduce nitric oxide and tumor necrosis factor-α production, hence preventing severe tissue damage. Furthermore, AMPs can also interfere with the Toll-like receptor 4 recognition system, suppressing cytokine production and contributing to modulate the inflammatory response. Here, we review the immune system strategies devised by AMPs to avoid an exacerbated inflammatory response and thus prevent a fatal end to the host.
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Affiliation(s)
- David Pulido
- Department of Biochemistry and Molecular Biology, Faculty of Biosciences, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
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Antimicrobial Peptide from the Eusocial BeeHalictus sexcinctusInteracting with Model Membranes. ACTA ACUST UNITED AC 2012. [DOI: 10.1155/2012/840956] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Halictine-1 (Hal-1)—a linear antibacterial dodecapeptide isolated from the venom of the eusocial beeHalictus sexcinctus—has been subjected to a detailed spectroscopic study including circular dichroism, fluorescence, and vibrational spectroscopy. We investigated Hal-1 ability to adopt an amphipathicα-helical structure upon interaction with model lipid-based bacterial membranes (phosphatidylcholine/phosphatidylglycerol-based large unilamellar vesicles and sodium dodecylsulfate micelles) and helix inducing components (trifluoroethanol). It was found that Hal-1 responds sensitively to the composition of the membrane model and to the peptide/lipid ratio. The amphipathic nature of the helical Hal-1 seems to favour flat charged surfaces of the model lipid particles over the nondirectional interaction with trifluoroethanol. Increasing fraction of polyproline II type conformation was detected at low peptide/lipid ratios.
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Fjell CD, Hiss JA, Hancock REW, Schneider G. Designing antimicrobial peptides: form follows function. Nat Rev Drug Discov 2011; 11:37-51. [PMID: 22173434 DOI: 10.1038/nrd3591] [Citation(s) in RCA: 1337] [Impact Index Per Article: 102.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Multidrug-resistant bacteria are a severe threat to public health. Conventional antibiotics are becoming increasingly ineffective as a result of resistance, and it is imperative to find new antibacterial strategies. Natural antimicrobials, known as host defence peptides or antimicrobial peptides, defend host organisms against microbes but most have modest direct antibiotic activity. Enhanced variants have been developed using straightforward design and optimization strategies and are being tested clinically. Here, we describe advanced computer-assisted design strategies that address the difficult problem of relating primary sequence to peptide structure, and are delivering more potent, cost-effective, broad-spectrum peptides as potential next-generation antibiotics.
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Affiliation(s)
- Christopher D Fjell
- Centre for Microbial Diseases and Immunity Research, University of British Columbia, 2259 Lower Mall, Vancouver, British Columbia V6T 1Z4, Canada
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