In vitro and in vivo antimicrobial activity of two α-helical cathelicidin peptides and of their synthetic analogs (original) (raw)
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Journal of Biological Chemistry, 1996
Cathelicidins are a family of myeloid antimicrobial peptide precursors that have been identified in several mammalian species (Zanetti, M., Gennaro, R., and Romeo, D. (1995) FEBS Lett. 374, 1-5). Two novel bovine congeners have been deduced from cDNA. Their C-terminal sequences of 27 and 28 residues correspond to putative antimicrobial peptides with a cationic N-terminal region predicted to assume an amphipathic ␣-helical conformation followed by a hydrophobic C-terminal tail. Peptides corresponding to these sequences have been chemically synthesized and shown to exert a potent antimicrobial activity against Gram-negative and Grampositive bacteria, including methicillin-resistant Staphylococcus aureus, and fungi. Both peptides are also cytotoxic to human erythrocytes and neutrophils, although at higher than microbicidal concentrations. The target selectivity has been improved by synthesizing truncated analogues, comprising only the 18 N-terminal residues, which show a great reduction in cytotoxic, but not in antimicrobial activity. The involvement of the C-terminal hydrophobic tail in the cytotoxic activity has been further demonstrated by inducing a major loss of activity in an analogue after replacing highly hydrophobic residues with more hydrophilic ones.
Cathelicidins: family of antimicrobial peptides. A review
Molecular Biology Reports, 2012
Cathelicidins are small, cationic, antimicrobial peptides found in humans and other species, including farm animals (cattle, horses, pigs, sheep, goats, chickens, rabbits and in some species of fish). These proteolytically activated peptides are part of the innate immune system of many vertebrates. These peptides show a broad spectrum of antimicrobial activity against bacteria, enveloped viruses and fungi. Apart from exerting direct antimicrobial effects, cathelicidins can also trigger specific defense responses in the host. Their roles in various pathophysiological conditions have been studied in mice and humans, but there are limited information about their expression sites and activities in livestock. The aim of the present review is to summarize current information about these antimicrobial peptides in farm animals, highlighting peptide expression sites, activities, and future applications for human and veterinary medicine.
Pure and Applied Chemistry, 2000
The effect of C-terminal amidation on the antimicrobial and hemolytic activities of antimicrobial peptides was studied using three cationic peptides which form amphiphilic α-helices when bound to membranes. The natural antimicrobial peptide PGLa, the designermade antibiotic MSI-103, and the cell-penetrating "model amphipathic peptide" (MAP) are all amidated in their original forms, and their biological activities were compared with the same sequences carrying a free C-terminus. It was found that, in general, a free COOH-terminus reduces both the antimicrobial activity and the hemolytic side effects of the peptides. The only exception was observed for MSI-103, whose antimicrobial activity was not decreased in the acid form. Having shown that the therapeutic index (TI) of this novel peptide is significantly higher than for the other tested peptides, with high antibiotic activity and little undesired effects, we suggest that it could be a useful starting point for further development of new peptide antibiotics. rupt also the cellular membranes of the eukaryotic organism to which they are being applied. In this regard, hemolytic side effects need to be minimized in order to turn a comparatively nonspecific antimicrobial peptide into a universally useful drug. There is high expectation of success, since the cell surface differs significantly between prokaryotes and eukaryotes not only with regard to lipid composition and cholesterol content, but also with regard to charge, the transmembrane potential, and other factors.
Biological characterization of a novel mammalian antimicrobial peptide
Biochimica et Biophysica Acta (BBA) - General Subjects, 1998
A putative antimicrobial peptide of 34 residues was recently deduced from a bovine cathelicidin gene sequence and named BMAP-34. A peptide based on the deduced sequence was chemically synthesized and used to study the localization, structure and biological activities of BMAP-34. A Western blot analysis using antibodies raised to the synthetic peptide showed that BMAP-34 is stored as proform in the cytoplasmic granules of bovine neutrophils. CD spectroscopy indicates that the peptide assumes an amphipathic K-helical conformation, as also predicted by secondary structure analysis. The peptide exerts a broad spectrum antimicrobial activity against both Gram-negative and Gram-positive organisms, and is not active against eukaryotic cells. When tested on Escherichia coli ML-35, the kinetics of bacterial killing and of inner membrane permeabilization are slower than those observed for other K-helical peptides derived from cathelicidins. ß 0304-4165 / 98 / $^see front matter ß 1998 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 -4 1 6 5 ( 9 8 ) 0 0 0 8 7 -7 * Corresponding
Antimicrobial Agents and Chemotherapy, 2006
Bacterial lipopolysaccharides (LPS) are important triggers of the widespread inflammatory response, which contributes to the development of multiple organ failure during sepsis. The helical 37-amino-acid-long human antimicrobial peptide LL-37 not only possesses a broad-spectrum antimicrobial activity but also binds and neutralizes LPS. However, the use of LL-37 in sepsis treatment is hampered by the fact that it is also cytotoxic. To find a less toxic analog of LL-37, we used in silico analysis to identify amphipathic helical regions of LL-37. A 21-amino-acid fragment (GKE) was synthesized, the biological actions of which were compared to those of two equally long peptides derived from the N and C termini of LL-37 as well as native LL-37. GKE displayed antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Candida parapsilosis that was similar to or even stronger than LL-37. GKE, as well as the equally long control pepti...
Journal of Biological Chemistry, 2005
In the present study, the 26-residue peptide sequence Ac-KWKSFLKTFKSAVKTVLHTALKAISSamide (V 681 ) was utilized as the framework to study the effects of peptide hydrophobicity/ hydrophilicity, amphipathicity, and helicity (induced by single amino acid substitutions in the center of the polar and nonpolar faces of the amphipathic helix) on biological activities. The peptide analogs were also studied by temperature profiling in reversed-phase high performance liquid chromatography, from 5 to 80 °C, to evaluate the self-associating ability of the molecules in solution, another important parameter in understanding peptide antimicrobial and hemolytic activities. A higher ability to self-associate in solution was correlated with weaker antimicrobial activity and stronger hemolytic activity of the peptides. Biological studies showed that strong hemolytic activity of the peptides generally correlated with high hydrophobicity, high amphipathicity, and high helicity. In most cases, the D-amino acid substituted peptides possessed an enhanced average antimicrobial activity compared with L-diastereomers. The therapeutic index of V 681 was improved 90-and 23fold against Gram-negative and Gram-positive bacteria, respectively. By simply replacing the central hydrophobic or hydrophilic amino acid residue on the nonpolar or the polar face of these amphipathic derivatives of V 681 with a series of selected D-/L-amino acids, we demonstrated that this method has excellent potential for the rational design of antimicrobial peptides with enhanced activities.
Analytical Biochemistry, 2006
To assess and compare different model Leu-Lys-containing cationic a-helical peptides, their antimicrobial activities were tested against Escherichia coli as target organism over a broad peptide concentration range. The natural cationic a-helical peptides magainin 2 and PGLa and the cyclic cationic peptide gramicidin S were also tested between comparison. The dose-response curves differed widely for these peptides, making it difficult to rank them into an activity order over the whole concentration range. We therefore compared five different inhibition parameters from dose-response curves: IC min (lowest concentration leading to growth inhibition), IC 50 (concentration that gives 50% growth inhibition), IC max (related to minimum inhibition concentration and minimum bactericidal concentration), inhibition concentration factor (IC F ; describing the increase in concentration of the peptide between minimum and maximum inhibition), and activity slope (A S ; related to the Hill coefficient). We found that these parameters were covariant: two of them sufficed to characterize the dose dependence and hence the activity of the peptides. This was corroborated by showing that the dose dependences followed the Hill equation, with a small, constant aberration. We propose that the activity of antimicrobial peptides can readily be characterized by both IC 50 and IC F (or A S ) rather than by a single parameter and discuss how this may relate to investigations into their mechanisms of action.
Molecular Immunology, 2009
Chicken host defense peptide cathelicidin-2 (CATH-2) is known to exert antimicrobial and immunomodulatory activities and consists of two ␣-helices connected by a hinge region. Here we report the biological properties of the separate ␣-helical segments and the importance of the proline residue in the hinge region. Substitution of proline-14 in the CATH-2 hinge region by leucine, but not by glycine, strongly reduced antibacterial and hemolytic activity. Furthermore, substitution by leucine strongly reduced the neutralization of LPS-induced cytokine production and peptide-induced monocyte chemotactic protein-1 (MCP-1) production by human peripheral blood mononuclear cells (PBMCs). This indicates that the hinge region is important for rapid penetration of the bacterial membrane as well as indirect and direct immunomodulatory activities. The highly cationic and amphipathic N-terminal segment (C1-15) exhibited very potent antibacterial activity and fast killing kinetics, while displaying low cytotoxicity towards chicken erythrocytes and PBMCs. The N-terminal and, to a lesser extent, the C-terminal helical regions potently neutralized LPS-induced release of TNF␣, IL-6 and IL-10 by PBMCs, while IL-8 production was only moderately affected. These results indicate that core elements within mature CATH-2 can be identified that are linked to antibacterial and/or immunomodulatory activities. Further studies may lead to the development of peptide antibiotics with specific properties that can be used for prophylactic and/or therapeutic applications.
BMC Microbiology, 2011
Background Chronic, infected wounds typically contain multiple genera of bacteria, including Staphylococcus aureus, many of which are strong biofilm formers. Bacterial biofilms are thought to be a direct impediment to wound healing. New therapies that focus on a biofilm approach may improve the recovery and healing rate for infected wounds. In this study, cathelicidins and related short, synthetic peptides were tested for their anti-microbial effectiveness as well as their ability to inhibit the ability of S. aureus to form biofilms. Results The helical human cathelicidin LL-37 was tested against S. aureus, and was found to exhibit effective anti-microbial, anti-attachment as well as anti-biofilm activity at concentrations in the low μg/ml range. The effect of peptide chirality and associated protease-resistance was explored through the use of an all-D amino acid peptide, D-LL-37, and in turn compared to scrambled LL-37. Helical cathelicidins have been identified in other animals su...