Interaction of cationic antimicrobial peptides with phospholipid vesicles and their antibacterial activity (original) (raw)
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Journal of Biological Chemistry, 2001
All known naturally occurring linear cationic peptides adopt an amphipathic ␣-helical conformation upon binding to lipids as an initial step in the induction of cell leakage. We designed an 18-residue peptide, (KIGAKI) 3-NH 2 , that has no amphipathic character as an ␣-helix but can form a highly amphipathic -sheet. When bound to lipids, (KIGAKI) 3-NH 2 did indeed form a -sheet structure as evidenced by Fourier transform infrared and circular dichroism spectroscopy. The antimicrobial activity of this peptide was compared with that of (KI-AGKIA) 3-NH 2 , and it was better than that of GMASKA-GAIAGKIAKVALKAL-NH 2 (PGLa) and (KLAGLAK) 3-NH 2 , all of which form amphipathic ␣-helices when bound to membranes. (KIGAKI) 3-NH 2 was much less effective at inducing leakage in lipid vesicles composed of mixtures of the acidic lipid, phosphatidylglycerol, and the neutral lipid, phosphatidylcholine, as compared with the other peptides. However, when phosphatidylethanolamine replaced phosphatidylcholine, the lytic potency of PGLa and the ␣-helical model peptides was reduced, whereas that of (KIGAKI) 3-NH 2 was improved. Fluorescence experiments using analogs containing a single tryptophan residue showed significant differences between (KIGAKI) 3-NH 2 and the ␣-helical peptides in their interactions with lipid vesicles. Because the data suggest enhanced selectivity between bacterial and mammalian lipids, linear amphipathic -sheet peptides such as (KIGAKI) 3-NH 2 warrant further investigation as potential antimicrobial agents.
Antimicrobial Agents and Chemotherapy, 2005
Many naturally occurring antimicrobial peptides comprise cationic linear sequences with the potential to adopt an amphipathic α-helical conformation. We designed a linear 18-residue peptide that adopted an amphipathic β-sheet structure when it was bound to lipids. In comparison to a 21-residue amphipathic α-helical peptide of equal charge and hydrophobicity, this peptide possessed more similar antimicrobial activity and greater selectivity in binding to and inducing leakage in vesicles composed of bacterial membrane lipids than vesicles composed of mammalian membrane lipids (J. Blazyk, R. Weigand, J. Klein, J. Hammer, R. M. Epand, R. F. Epand, W. L. Maloy, and U. P. Kari, J. Biol. Chem. 276:27899-27906, 2001). Here, we compare two systematically designed families of linear cationic peptides to evaluate the importance of amphipathicity for determination of antimicrobial activity. Each peptide contains six lysine residues and is amidated at the carboxyl terminus. The first family cons...
Influence of the Length and Charge on the Activity of α-Helical Amphipathic Antimicrobial Peptides
Biochemistry, 2017
Hydrophobic mismatch is important for pore-forming amphipathic antimicrobial peptides, as demonstrated recently [Grau-Campistany, A., et al. (2015) Sci. Rep. 5, 9388]. A series of different length peptides have been generated with the heptameric repeat sequence KIAGKIA, called KIA peptides, and it was found that only those helices sufficiently long to span the hydrophobic thickness of the membrane could induce leakage in lipid vesicles; there was also a clear length dependence of the antimicrobial and hemolytic activities. For the original KIA sequences, the cationic charge increased with peptide length. The goal of this work is to examine whether the charge also has an effect on activity; hence, we constructed two further series of peptides with a sequence similar to those of the KIA peptides, but with a constant charge of +7 for all lengths from 14 to 28 amino acids. For both of these new series, a clear length dependence similar to that of KIA peptides was observed, indicating th...
Biophysical Journal, 2010
Five AHCAPs exhibiting a broad-spectrum of antimicrobial activity, were examined with regard to their action in lipid mixtures with two anionic lipids, PG and CL. We find that all of the peptides studied were capable of promoting the formation of crystalline phases of DMPG in mixtures of DMPG and CL, without prior incubation at low temperatures. This property is indicative of the ability of these peptides to cluster CL away from DMPG. In contrast, the well studied antimicrobial cationic peptide magainin 2 does not cluster anionic lipids. We ascribe the lower anionic lipid clustering ability of magainin to its low density of positive charges compared with the five other AHCAPs used in this work. The peptide MSI-1254 was particularly potent in segregating these two anionic lipids. Consequently, clusters enriched in DMPG appear in a lipid mixture with CL. These can rapidly form higher temperature crystalline phases because of the increased permeability of the bilayer caused by the AHCAPs. The polyaminoacids, poly-L-Lysine and poly-L-arginine are also very effective in causing this segregation. Thus, the clustering of anionic lipids by AHCAPs is not confined only to mixtures of anionic with zwitterionic lipids, but it extends to mixtures containing different anionic headgroups. The resulting effects, however, have different consequences to the biological activity. This finding broadens the scope for which an AHCAP agent will cluster lipids in a membrane.
FEBS Letters, 1997
Starting from the sequences of magainin 2 analogs, peptides with slightly increased hydrophobic moment (/x) but retained other structural parameters were designed. Circular dichroism investigations revealed that all peptides adopt an (Xhelical conformation when bound to phospholipid vesicles. Analogs with increased \i were considerably more active in permeabilizing vesicles mainly composed of zwitterionic lipid. In addition, the antibacterial and hemolytic activities of these analogs were enhanced. Correlation of permeabilization and binding indicated that the activity increase is predominantly caused by an increased membrane affinity of the peptides due to strengthened hydrophobic interactions.
Journal of Biological Chemistry, 2009
Designed histidine-rich amphipathic cationic peptides, such as LAH4, have enhanced membrane disruption and antibiotic properties when the peptide adopts an alignment parallel to the membrane surface. Although this was previously achieved by lowering the pH, here we have designed a new generation of histidine-rich peptides that adopt a surface alignment at neutral pH. In vitro, this new generation of peptides are powerful antibiotics in terms of the concentrations required for antibiotic activity; the spectrum of target bacteria, fungi, and parasites; and the speed with which they kill. Further modifications to the peptides, including the addition of more hydrophobic residues at the N terminus, the inclusion of a helix-breaking proline residue or using D-amino acids as building blocks, modulated the biophysical properties of the peptides and led to substantial changes in toxicity to human and parasite cells but had only a minimal effect on the antibacterial and antifungal activity. Using a range of biophysical methods, in particular solid-state NMR, we show that the peptides are highly efficient at disrupting the anionic lipid component of model membranes. However, we also show that effective pore formation in such model membranes may be related to, but is not essential for, high antimicrobial activity by cationic amphipathic helical peptides. The information in this study comprises a new layer of detail in the understanding of the action of cationic helical antimicrobial peptides and shows that rational design is capable of producing potentially therapeutic membrane active peptides with properties tailored to their function.
International Journal of Antimicrobial Agents, 2003
The bactericidal potency of a synthetic peptide (CG 117 Á/136) of human lysosomal cathepsin G (cat G) can be substantially increased by covalent attachment to its N-or C-termini, of saturated, linear fatty acids (FAs), namely those with C-8, C-10 and C-12 hydrocarbon chains. In order to understand better the mechanism by which FA moieties increase the bactericidal activity of CG 117 Á/136, the interaction of N -terminally FA-modified peptides with artificial membranes was studied. First, the content of secondary structure motifs in the modified and unmodified peptides was determined by circular dichroism (CD). A marked increase in the propensity of FA-modified CG 117 Á/136 to form an a-helix structure was observed for the C-8, C-10 and C-12 derivatives compared with unmodified/short-chain and long-chain (C-14, C-16, C-18) derivatives. These effects were observed both in the presence of large unilamellar liposomes or in trifuluoroethanol, a membrane-stimulating agent. Second, the capacity of peptides to insert into large unilamellar liposomes as a function of FA length was determined by their ability to release a trapped fluorescent dye. FA derivatives with the highest a-helical content were found to be the most effective in releasing a fluorescent dye, compared with an unmodified peptide and/or derivatives having a low a-helical content. The ability of the peptides to attain a-helical structure in the membrane-like environment and the ability to disrupt the liposomal membrane, therefore correlate remarkably well with their increased ability to kill bacteria. A plausible explanation for improved bactericidal action of the modified peptide is that the FA moiety facilitates formation of the peptide with an a-helical structure formation in membranes, which is essential for disrupting the integrity of the bacterial cytoplasmic membrane. #