Lipid Headgroup Discrimination by Antimicrobial Peptide LL-37: Insight into Mechanism of Action

Neville, Frances; Cahuzac, Marjolaine; Konovalov, Oleg; Ishitsuka, Yuji; Lee, Ka Yee C.; Kuzmenko, Ivan; Kale, Girish M.; Gidalevitz, David

doi:10.1529/biophysj.105.067595

Cited by 149 publications

(208 citation statements)

References 71 publications

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“…7, circles) fit well with a two-slab model, yielding a hydrocarbon tail density ( t / s ) of 0.99 and a hydrocarbon tail slab thickness (L 1 ) of 17.9 Å as well as a head-group electron density ( h / s ) of 1.54 and head-group slab thickness (L 2 ) of 5.7 Å. These data are in good agreement with previous DPPG monolayer x-ray work (51). The XR profile changed dramatically after 1 was introduced (Fig.…”

Section: X-ray Reflectivity Studies Of Ampetoid Orientation In Lipid supporting

confidence: 87%

“…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%

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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.

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568

578

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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...

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Section: X-ray Reflectivity Studies Of Ampetoid Orientation In Lipid supporting

confidence: 87%

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.

Self Cite

568

578

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show abstract

“…Further, it is very reasonable that no water molecules exist in the tailgroup, because the tailgroup are composed of two linear aliphatic chains, which are highly hydrophobic. In that case, the expanded region will not be filled efficiently with water molecules, but remained empty [23][24][25]. Consequently the electron densities of head and tail layer will be reduced by the peptide insertion (Figure 3(c)).…”

Section: X-ray Reflectivity Of Tdp On Model Phospholipid Monolayersmentioning

confidence: 99%

X‐ray reflectivity study of a transcription‐activating factor‐derived peptide penetration into the model phospholipid monolayers

Tae

Yang

Shin

et al. 2007

Journal of Peptide Science

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Abstract:The penetration of a transcription-activating factor (TAT)-derived, cell-penetration peptide onto 1,2-dipalmitoyl-snglycero-3-phosphocholine (DPPC) or 1,2-dipalmitoyl-sn-glycero-3-[phospho-L-serine] (DPPS) monolayer on phosphate-buffered saline subphase was characterized. The surface area at the target pressure increased noticeably by the peptide penetration from the subphase to the phospholipid monolayer, which might suggest a direct penetration of the peptide across the pure phospholipid bilayer membrane. Interestingly, the more significant area increase at 35 mN/m was monitored from DPPC monolayer, contrary to the simple charge interaction: the net neutral DPPC, the net-negative DPPS, and the positive TAT-derived peptides (TDP). X-ray reflectivity measurements as well as the molecular area from π (surface pressure)-A (area) isotherms suggest that the packing density of DPPS at the target pressure is too high to allow the effective penetration of the peptide into the monolayer and the positively charged peptides can be entrapped at the negative electrostatic well of DPPS headgroup layer, leading to the simple adsorption on the DPPS monolayer instead of penetration into it. Thus, more penetration with less adsorption of the peptide is induced by DPPC monolayer than DPPS monolayer.

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“…Our current understanding of how this AMP attacks bacteria has been shaped by bulk assays (11,12), model membrane assays (13)(14)(15)(16)(17)(18), and assumptions based on studies of other AMPs. Minimum inhibitory concentration (MIC) assays, which determine the lowest concentration of peptide that inhibits bacterial growth, show that LL-37 is effective against a broad spectrum of bacteria that is both Gram-positive and -negative (12).…”

mentioning

confidence: 99%

Real-time attack on single Escherichia coli cells by the human antimicrobial peptide LL-37

Sochacki

Barns²,

Bucki³

et al. 2011

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

234

272

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Natural antimicrobial peptides (AMPs) provide prototypes for the design of unconventional antimicrobial agents. Existing bulk assays measure AMP activity but do not provide details of the growthhalting mechanism. We use fluorescence microscopy to directly observe the attack of the human antimicrobial peptide LL-37 on single Escherichia coli cells in real time. Our findings strongly suggest that disruption of the cytoplasmic membrane is not the growth-halting mechanism. At 8 μM, LL-37 binding saturates the outer membrane (OM) within 1 min. Translocation across the OM and access to the periplasmic space (5-25 min later) correlates in time with the halting of growth. Septating cells are attacked more readily than nonseptating cells. The halting of growth may occur because of LL-37 interference with cell wall biogenesis. Only well after growth halts does the peptide permeabilize the cytoplasmic membrane to GFP and the small dye Sytox Green. The assay enables dissection of antimicrobial design criteria into two parts: translocation across the OM and the subsequent halting of growth.

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Lipid Headgroup Discrimination by Antimicrobial Peptide LL-37: Insight into Mechanism of Action

Cited by 149 publications

References 71 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

X‐ray reflectivity study of a transcription‐activating factor‐derived peptide penetration into the model phospholipid monolayers

Real-time attack on single Escherichia coli cells by the human antimicrobial peptide LL-37

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