Voltage-Dependent Pore Formation and Antimicrobial Activity by Alamethicin and Analogues

Duclohier, H.; Wróblewski, Henri

doi:10.1007/s00232-001-0077-2

Cited by 132 publications

(95 citation statements)

References 92 publications

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“…In the case of hydrophobic peptides such as alamethicin, experimental data indicate that permeabilization occurs through the formation of ion-conducting transmembrane channels in accordance with the Ôbarrel-staveÕ model [35,48]. However, such a mechanism hardly fits LK peptides, even the a-helical ones, because of their polycationic nature and charge periodicity (+1 per a-helix turn).…”

Section: Discussionmentioning

confidence: 94%

The antibiotic activity of cationic linear amphipathic peptides: lessons from the action of leucine/lysine copolymers on bacteria of the class Mollicutes

Béven

Castano

Dufourcq

et al. 2003

European Journal of Biochemistry

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Peptides composed of leucyl and lysyl residues (ÔLK peptidesÕ) with different compositions and sequences were compared for their antibacterial activities using cell wall-less bacteria of the class Mollicutes (acholeplasmas, mycoplasmas and spiroplasmas) as targets. The antibacterial activity of the amphipathic a-helical peptides varied with their size, 15 residues being the optimal length, independent of the membrane hydrophobic core thickness and the amount of cholesterol. The 15-residue ideally amphipathic a helix with a +5 positive net charge (KLLKLLLKLLLKLLK) had the strongest antibacterial activity, similar to that of melittin. In contrast, scrambled peptides devoid of amphipathy and the less hydrophobic b-sheeted peptides [(LK) n K], even those 15-residue long, were far less potent than the helical ones. Furthermore, the growth inhibitory activity of the peptides was correlated with their ability to abolish membrane potential. These data are fully consistent with a predominantly flat orientation of LK peptides at the lipid/ water interface and strongly supports that these peptides and probably the linear polycationic amphipathic defence peptides act on bacterial membranes in four main steps according to the ÔcarpetÕ model: (a) interfacial partitioning with accumulation of monomers on the target membrane (limiting step); (b) peptide structural changes (conformation, aggregation, and orientation) induced by interactions with the lipid bilayer (as already shown with liposomes and erythrocytes); (c) plasma membrane permeabilization/ depolarization via a detergent-like effect; and (d) rapid bacterial cell death if the extent of depolarization is maintained above a critical threshold.Keywords: amphipathic peptides; antibacterial activity; bacterial cell death; membrane depolarization; mollicutes.The amphipathic a helix concept helps in understanding the behaviour of very different classes of proteins and peptides, especially those acting on membranes [1][2][3][4]. This concept, which has been useful in the field of peptidic cytotoxins to develop new analogues, and to better understand their mode of action [5][6][7], is still the basis for the rational design of new antimicrobial compounds, i.e. analogues or chimeras of natural products [8], or radically new molecules [9,10].The need to understand their mode of action and improve their efficacy and/or selectivity towards microorganisms led to the synthesis of new active peptides, made possible largely by the progress in solid state synthesis. As a result, a large wealth of information was obtained on many natural peptides endowed with cytotoxic (including antimicrobial) activity. However, answers are still missing regarding: (a) the requirements for optimized activity and selectivity; and (b) the mechanisms of action, especially in bacterial cells. In an effort of rationalization, a minimalistic approach was initiated by the pioneering work of De Grado and Lear [11] using residue substitutions or designing simplified sequences [2,[12][13][14]. Using the very mini...

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Section: Discussionmentioning

confidence: 94%

The antibiotic activity of cationic linear amphipathic peptides: lessons from the action of leucine/lysine copolymers on bacteria of the class Mollicutes

Béven

Castano

Dufourcq

et al. 2003

European Journal of Biochemistry

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“…The antimycoplasma activities of the peptides were assayed as described previously (6). For the determination of MICs, mycoplasmas (initial concentration, 10 6 CFU/ml) were cultured in 96-well plates in the presence of twofold serial dilutions of the different antibiotics (0 to 100 M). A change in the color of the phenol red indicator due to medium acidification was used as an indicator of bacterial growth.…”

Section: Methodsmentioning

confidence: 99%

“…Using the HeLa cell-mycoplasma model system, we have evaluated the antimycoplasma activities of four peptides: (i) dermaseptin B2, a 33-residue linear peptide isolated from the frog Phyllomedusa bicolor (8); (ii) alamethicin, a 20-residue ␣-methylalanine-containing peptide produced by the fungus Trichoderma viride (10,27); (iii) surfactin, an 8-residue cyclic lipopeptide from Bacillus subtilis (2); and (iv) gramicidin S (or tyrocidin S), a 10-residue peptide which is produced by Bacillus brevis and which, similar to surfactin, is also cyclic but not acylated (22). We also compared the activities of these peptides with that of enrofloxacin, a fluoroquinolone that is used in veterinary practice and that is known to have potent activity against mycoplasmas (23).…”

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confidence: 99%

Susceptibilities of Mycoplasma fermentans and Mycoplasma hyorhinis to Membrane-Active Peptides and Enrofloxacin in Human Tissue Cell Cultures

Nir-Paz

Prévost

Nicolas

et al. 2002

Antimicrob Agents Chemother

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Mycoplasmas, which are bacteria that are devoid of a cell wall and which belong to the class Mollicutes, are pathogenic for humans and animals and are frequent contaminants of tissue cell cultures. Although contamination of cultures with mycoplasma can easily be monitored with fluorescent dyes that stain DNA and/or with molecular probes, protection and decontamination of cultures remain serious challenges. In the present work, we investigated the susceptibilities of Mycoplasma fermentans and Mycoplasma hyorhinis to the membrane-active peptides alamethicin, dermaseptin B2, gramicidin S, and surfactin by growth inhibition and lethality assays. In the absence of serum, the four peptides killed mycoplasmas at minimal bactericidal concentrations that ranged from 12.5 to 100 M, but in all cases the activities were decreased by the presence of serum. As a result, under standard culture conditions (10% serum) only alamethicin and gramicidin S were able to inhibit mycoplasma growth (MICs, 50 M), while dermaseptin B2 and surfactin were ineffective. Furthermore, 8 days of treatment of HeLa cell cultures experimentally contaminated with either mycoplasma species with 70 M enrofloxacin cured the cultures of infection, whereas treatment with alamethicin and gramicidin S alone was not reliable because the concentrations and treatment times required were toxic to the cells. However, combination of alamethicin or gramicidin S with 70 M enrofloxacin allowed mycoplasma eradication after 30 min or 24 h of treatment, depending on the mycoplasma and peptide considered. HeLa cell cultures experimentally infected with mycoplasmas should prove to be a useful model for study of the antimycoplasma activities of antibiotics and membrane-active peptides under conditions close to those found in vivo.

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“…Being cationic, the peptides interact electrostatically with the negatively charged phospholipid headgroups and insert into the membrane bilayer in a manner that leads to its disruption (22,33,35,42,65). Although the steps involved in this mechanism remain to be delineated, there is a large body of experimental data demonstrating that antimicrobial peptides display a direct correlation between antibiotic effect and increased plasma membrane permeability, conductance of ions across lipid bilayers, and dissipation of the transmembrane electric potential (17,21,24,39,49,58,59,62,68,66). Thus, while their precise mechanism of action is not fully understood, their microbicidal effect is believed to result from the peptides' capacity to disrupt the ordered membrane structure of target cells.…”

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confidence: 99%

A Chimeric Peptide Composed of a Dermaseptin Derivative and an RNA III-Inhibiting Peptide Prevents Graft-Associated Infections by Antibiotic-Resistant Staphylococci

Balaban

Gov

Giacometti

et al. 2004

Antimicrob Agents Chemother

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Staphylococcal bacteria are a prevalent cause of infections associated with foreign bodies and indwelling medical devices. Bacteria are capable of escaping antibiotic treatment through encapsulation into biofilms. RNA III-inhibiting peptide (RIP) is a heptapeptide that inhibits staphylococcal biofilm formation by obstructing quorum-sensing mechanisms. K 4 -S4(1-13) a is a 13-residue dermaseptin derivative (DD 13 ) believed to kill bacteria via membrane disruption. We tested each of these peptides as well as a hybrid construct, DD 13 -RIP, for their ability to inhibit bacterial proliferation and suppress quorum sensing in vitro and for their efficacy in preventing staphylococcal infection in a rat graft infection model with methicillin-resistant Staphylococcus aureus (MRSA) or S. epidermidis (MRSE). In vitro, proliferation assays demonstrated that RIP had no inhibitory effect, while DD 13 -RIP and DD 13 were equally effective, and that the chimeric peptide but not DD 13 was slightly more effective than RIP in inhibiting RNA III synthesis, a regulatory RNA molecule important for staphylococcal pathogenesis. In vivo, the three peptides reduced graft-associated bacterial load in a dosedependent manner, but the hybrid peptide was most potent in totally preventing staphylococcal infections at the lowest dose. In addition, each of the peptides acted synergistically with antibiotics. The data indicate that RIP and DD 13 act in synergy by attacking bacteria simultaneously by two different mechanisms. Such a chimeric peptide may be useful for coating medical devices to prevent drug-resistant staphylococcal infections. Nosocomial infections due to Staphylococcus aureus andStaphylococcus epidermidis have increased over the last decades (36, 41, 42). These common skin bacteria are also known to be a frequent cause of infections related to prosthetic and indwelling medical devices (16,46), where these infections are related to bacterial biofilm formation on material surfaces, such as venous or urinary catheters, prosthetic heart valves, orthopedic devices, and contact lenses (16,40,46,63). In particular, the late-appearing vascular graft infections are one of the most feared complications that the vascular surgeon treats, frequently resulting in prolonged hospitalization, organ failure, amputation, and death (7, 34).Effective strategies for the prevention of prosthetic infections vary and include the use of antimicrobials bound in high concentrations to prosthetic grafts (11,44,63,69,71). Because of the increase in resistance to antibiotics, several studies have focused on developing new prosthetic materials that reduce biofilm formation (28,71). One of the most interesting studies was based on the fact that the resistance of a biofilm to antimicrobial agents is acquired as a multicellular strategy that relies on exchange of chemical signals between cells in a process known as quorum sensing (48). Thus, interfering with this mechanism of bacterial cell-cell communication could provide a novel approach to prevent biofilm forma...

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Voltage-Dependent Pore Formation and Antimicrobial Activity by Alamethicin and Analogues

Cited by 132 publications

References 92 publications

The antibiotic activity of cationic linear amphipathic peptides: lessons from the action of leucine/lysine copolymers on bacteria of the class Mollicutes

The antibiotic activity of cationic linear amphipathic peptides: lessons from the action of leucine/lysine copolymers on bacteria of the class Mollicutes

Susceptibilities of Mycoplasma fermentans and Mycoplasma hyorhinis to Membrane-Active Peptides and Enrofloxacin in Human Tissue Cell Cultures

A Chimeric Peptide Composed of a Dermaseptin Derivative and an RNA III-Inhibiting Peptide Prevents Graft-Associated Infections by Antibiotic-Resistant Staphylococci

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