Solid-State NMR Investigation of the Membrane-Disrupting Mechanism of Antimicrobial Peptides MSI-78 and MSI-594 Derived from Magainin 2 and Melittin

Ramamoorthy, Ayyalusamy; Thennarasu, Sathiah; Lee, Dong Kuk; Tan, Anmin; Maloy, Lee

doi:10.1529/biophysj.105.073890

Cited by 252 publications

(277 citation statements)

References 52 publications

(66 reference statements)

Supporting

Mentioning

239

Contrasting

Order By: Relevance

“…The orientation of 1 at an angle of Ϸ56°to the interface normal suggests that 1 does not operate through a barrel-stave mechanism, because that would require a transmembrane configuration (5). Although it cannot be concluded that 1 exhibits identical mechanistic behavior to natural, ␣-helical antimicrobial peptides, these x-ray results demonstrate ampetoid-lipid interactions consistent with those seen for AMPs such as pexiganan (53) and LL-37 (51).…”

Section: Discussionmentioning

confidence: 54%

Peptoids that mimic the structure, function, and mechanism of helical antimicrobial peptides

Chongsiriwatana¹,

Patch²,

Czyzewski³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

565

578

View full text Add to dashboard Cite

Antimicrobial peptides (AMPs) and their mimics are emerging as promising antibiotic agents. We present a library of ''ampetoids'' (antimicrobial peptoid oligomers) with helical structures and biomimetic sequences, several members of which have low-micromolar antimicrobial activities, similar to cationic AMPs like pexiganan. Broad-spectrum activity against six clinically relevant BSL2 pathogens is also shown. This comprehensive structure-activity relationship study, including circular dichroism spectroscopy, minimum inhibitory concentration assays, hemolysis and mammalian cell toxicity studies, and specular x-ray reflectivity measurements shows that the in vitro activities of ampetoids are strikingly similar to those of AMPs themselves, suggesting a strong mechanistic analogy. The ampetoids' antibacterial activity, coupled with their low cytotoxicity against mammalian cells, make them a promising class of antimicrobials for biomedical applications. Peptoids are biostable, with a protease-resistant N-substituted glycine backbone, and their sequences are highly tunable, because an extensive diversity of side chains can be incorporated via facile solid-phase synthesis. Our findings add to the growing evidence that nonnatural foldamers will emerge as an important class of therapeutics.antibiotics ͉ peptidomimetics ͉ structure-activity studies N atural antimicrobial peptides (AMPs) defend a wide array of organisms against bacterial pathogens and show potential as supplements for or replacements of conventional antibiotics, because few bacteria have evolved resistance to them (1-3). Many AMPs kill bacteria by permeabilization of the cytoplasmic membrane, causing depolarization, leakage, and death (4), whereas others target additional anionic bacterial constituents (e.g., DNA, RNA, or cell wall components) (2, 5). Amphipathic secondary structures in which residues are segregated into hydrophobic and cationic regions ( Fig. 1 A and B) are the hallmark of most AMPs (6). Regardless of their final target of killing, AMPs must interact with the bacterial cytoplasmic membrane, and their amphipathicity is integral to such interactions (1, 2, 7). Additionally, their cationic nature imparts AMPs with some measure of selectivity, because mammalian cell membranes are largely zwitterionic. The precise nature of AMP-membrane interactions remains controversial and actively debated; a variety of mechanisms have been proposed, including the carpet (4), barrel-stave pore (4), toroidal pore (8), and aggregate (9) models. Nevertheless, a considerable number of structure-activity investigations have elucidated how the physicochemical properties of these molecules relate to their biological activities (4,7,(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22).Although AMPs have been actively studied for decades (23-25), they have yet to see widespread clinical use (1). This is due in part to the vulnerability of many peptide therapeutics to rapid in vivo degradation, which dramatically reduces their bioavailability. Nonnatural mimics of AMPs...

show abstract

Section: Discussionmentioning

confidence: 54%

Peptoids that mimic the structure, function, and mechanism of helical antimicrobial peptides

Chongsiriwatana¹,

Patch²,

Czyzewski³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

565

578

View full text Add to dashboard Cite

show abstract

“…The resulting increase in the separation of the anionic lipids allows an increase in the disorder, or cis-trans isomerizations, at the level of the fatty acyl chains that is reflected in the observed reduction-of-order parameter throughout the acyl chain. This model can be compared with a previous study of the membrane insertion of ethanol at the hydrocarbon-water interface (3), where the hydrophobic core of the membrane also becomes disordered, albeit at rather high ethanol concentrations, and a very recent study of the effect of both melittin-and magainin-derived peptides on deuterated phosphatidylcholine (28), where both these peptides adopt an in-plane orientation and disrupt the acyl chain order in a fashion similar to that shown here for the LAH peptides at acidic pH.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Membrane Disruption and Antibiotic Action against Pathogenic Bacteria by Designed Histidine-Rich Peptides at Acidic pH

Mason

Gasnier

Kichler

et al. 2006

Antimicrob Agents Chemother

View full text Add to dashboard Cite

The histidine-rich amphipathic cationic peptide LAH4 has antibiotic and DNA delivery capabilities. Here, we explore the interaction of peptides from this family with model membranes as monitored by solid-state 2 H nuclear magnetic resonance and their antibiotic activities against a range of bacteria. At neutral pH, the membrane disruption is weak, but at acidic pH, the peptides strongly disturb the anionic lipid component of bacterial membranes and cause bacterial lysis. The peptides are effective antibiotics at both pH 7.2 and pH 5.5, although the antibacterial activity is strongly affected by the change in pH. At neutral pH, the LAH peptides were active against both methicillin-resistant and -sensitive Staphylococcus aureus strains but ineffective against Pseudomonas aeruginosa. In contrast, the LAH peptides were highly active against P. aeruginosa in an acidic environment, as is found in the epithelial-lining fluid of cystic fibrosis patients. Our results show that modest antibiotic activity of histidine-rich peptides can be dramatically enhanced by inducing membrane disruption, in this case by lowering the pH, and that histidine-rich peptides have potential as future antibiotic agents.With the dramatic rise of antibiotic resistance in pathogenic bacteria, there is no doubt that there is an urgent requirement for the development of novel antibiotics. The lungs of cystic fibrosis patients are chronically infected by lineages of Pseudomonas aeruginosa with high mutation rates that can readily become resistant to current antibiotics (20,25), while the impact of methicillin-resistant Staphylococcus aureus (MRSA) has been well documented (2). These bacteria, therefore, represent significant targets for new classes of antibiotics.Cationic antimicrobial peptides play a central role in preventing the onset of infection in many organisms, and following the introduction of a number of such peptides in clinical trials (16), it seems likely that development of these peptides will provide the basis for a new class of antibiotics. LAH4, a histidine-rich amphipathic ␣-helical peptide (4), has been shown to possess both antibiotic (34) and DNA delivery (17, 18) capabilities. This dual functionality could be exploited in therapeutic strategies for a number of diseases, a notable example being cystic fibrosis, where LAH4 or a derivative thereof could form part of a gene delivery vehicle while concomitantly fighting microbial infections that result from the underlying condition. Therefore, a fundamental understanding of the antibiotic strategies employed by cationic antimicrobial peptides such as LAH4 will aid the design of more powerful antibiotics that may eventually become frontline treatments for a variety of infectious diseases.To understand in greater detail how histidine-rich peptides operate against their microbial targets, we synthesized a series of derivatives of LAH4 and combined biophysical studies of their interactions using model membranes from solid-state nuclear magnetic resonance (NMR) of chain-deuterated lipid...

show abstract

“…The lead 22-mer peptide MSI-78 has 62% helicity, whereas helicity values around 40−45% have been reported by Mercke et al for this peptide when bound to POPC small unilamellar vesicles (SUV). 34,35 For MSI-78(4−20) the determined mean helix content was 33%, which shows a difference of approximately 30% in the helix content between the two peptides. Figure 4D represents the helical wheel projections of the peptides where the relative position of the amino acids and its polar/nonpolar character is displayed.…”

Section: Molecular Pharmaceuticsmentioning

confidence: 95%

A 17-mer Membrane-Active MSI-78 Derivative with Improved Selectivity toward Bacterial Cells

et al. 2015

View full text Add to dashboard Cite

Antimicrobial peptides are widely recognized as an excellent alternative to conventional antibiotics. MSI-78, a highly effective and broad spectrum AMP, is one of the most promising AMPs for clinical application. In this study, we have designed shorter derivatives of MSI-78 with the aim of improving selectivity while maintaining antimicrobial activity. Shorter 17-mer derivatives were created by truncating MSI-78 at the N-and/or C-termini, while spanning MSI-78 sequence. Despite the truncations made, we found a 17-mer peptide, MSI-78(4−20) (KFLKKAKKFGKAFVKIL), which was demonstrated to be as effective as MSI-78 against the Gram-positive Staphylococcus strains tested and the Gram-negative Pseudomonas aeruginosa. This shorter derivative is more selective toward bacterial cells as it was less toxic to erythrocytes than MSI-78, representing an improved version of the lead peptide. Biophysical studies support a mechanism of action for based on the disruption of the bacterial membrane permeability barrier, which in turn leads to loss of membrane integrity and ultimately to cell death. These features point to a mechanism of action similar to the one described for the lead peptide MSI-78.

show abstract

Solid-State NMR Investigation of the Membrane-Disrupting Mechanism of Antimicrobial Peptides MSI-78 and MSI-594 Derived from Magainin 2 and Melittin

Cited by 252 publications

References 52 publications

Peptoids that mimic the structure, function, and mechanism of helical antimicrobial peptides

Peptoids that mimic the structure, function, and mechanism of helical antimicrobial peptides

Enhanced Membrane Disruption and Antibiotic Action against Pathogenic Bacteria by Designed Histidine-Rich Peptides at Acidic pH

A 17-mer Membrane-Active MSI-78 Derivative with Improved Selectivity toward Bacterial Cells

Contact Info

Product

Resources

About