Bacterial Membranes as Predictors of Antimicrobial Potency

Epand, Richard M.; Rotem, Shahar; Mor, Amram; Berno, Bob; Epand, Raquel F.

doi:10.1021/ja8062327

Cited by 161 publications

(175 citation statements)

References 35 publications

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“…Langmuir monolayers, LB films and liposomes of different composition were selected as membrane models. Gram negative membranes are mostly composed of two main phospholipids: zwitterionic PE and anionic PG, and Gram positive bacteria have a membrane that is almost entirely formed by anionic phospholipids, such as PG [21]. The outer leaflet of mammalian cell membranes is mainly composed of PC, which is charge-neutral at physiological pH.…”

Section: Discussionmentioning

confidence: 99%

“…Herein we present biophysical studies to understand the membrane disruption mechanism for sp-85 using monolayers and bilayers as bacterial membrane models. Gram positive cytoplasmic membrane is modeled with POPG, whereas the Gram negative membrane is best mimicked with a binary mixture of POPE:POPG (molar ratio 6:4) [21]. Eukaryotic membranes tend to be neutral, and are modeled with zwitterionic POPC.…”

Section: Introductionmentioning

confidence: 99%

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Membrane interaction of a new synthetic antimicrobial lipopeptide sp-85 with broad spectrum activity

Grau-Campistany

Pujol

Marqués

et al. 2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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ARTICLE IN PRESS• Sp-85 is a new synthetic antibiotic lipopeptide with broad spectrum activity.• Pressure-area curves of mixed monolayers show non-ideal mixing.• Binding to anionic liposomes results in fusion and leakage of aqueous contents.• TEM images of antibiotic-exposed bacteria show damaged membranes.• A mechanism of action based on bacterial membrane destabilization is proposed.g r a p h i c a l a b s t r a c t a r t i c l e i n f o a b s t r a c tAntimicrobial peptides offer a new class of therapeutic agents to which bacteria may not be able to develop genetic resistance, since their main activity is in the lipid component of the bacterial cell membrane. We have developed a series of synthetic cationic cyclic lipopeptides based on natural polymyxin, and in this work we explore the interaction of sp-85, an analog that contains a C12 fatty acid at the N-terminus and two residues of arginine. This analog has been selected from its broad spectrum antibacterial activity in the micromolar range, and it has a disruptive action on the cytoplasmic membrane of bacteria, as demonstrated by TEM. In order to obtain information on the interaction of this analog with membrane lipids, we have obtained thermodynamic parameters from mixed monolayers prepared with POPG and POPE/POPG (molar ratio 6:4), as models of Gram positive and Gram negative bacteria, respectively. Langmuir-Blodgett films have been extracted on glass plates and observed by confocal microscopy, and images are consistent with a strong destabilizing effect on the membrane organization induced by sp-85. The effect of sp-85 on the membrane is confirmed with unilamelar lipid vesicles of the same composition, where biophysical experiments based on fluorescence are indicative of membrane fusion and permeabilization starting at very low concentrations of peptide and only if anionic lipids are present. Overall, results described here provide strong evidence that the mode of action of sp-85 is the alteration of the bacterial membrane permeability barrier.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Membrane interaction of a new synthetic antimicrobial lipopeptide sp-85 with broad spectrum activity

Grau-Campistany

Pujol

Marqués

et al. 2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…Since daptomycin is selective for bacterial membranes, the question arose what role acidic lipids might have in its activity. The two acidic phospholipids phosphatidylglycerol and cardiolipin ( Figure 5) are abundant in bacterial membranes, 62 and as it turns out, both affect the function of daptomycin. At least some of these effects can be observed both with bacterial cells and with model membranes.…”

Section: Lipid Specificitymentioning

confidence: 95%

The action mechanism of daptomycin

Taylor

Palmer

2016

Bioorganic & Medicinal Chemistry

237

172

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Daptomycin is a lipopeptide antibiotic produced by the soil bacterium Streptomyces roseosporus that is clinically used to treat severe infections with Grampositive bacteria. In this review, we discuss the mode of action of this important antibiotic. Although daptomycin is structurally related to amphomycin and similar lipopeptides that inhibit peptidoglycan biosynthesis, experimental studies have not produced clear evidence that daptomycin shares their action mechanism. Instead, the best characterized effect of daptomycin is the permeabilization and depolarization of the bacterial cell membrane. This activity, which can account for daptomycin's bactericidal effect, correlates with the level of phosphatidylglycerol (PG) in the membrane. Accordingly, reduced synthesis of PG or its increased conversion to lysyl-PG promotes bacterial resistance to daptomycin. While other resistance mechanisms suggest that daptomycin may indeed directly interfere with cell wall synthesis or cell division, such effects still await direct experimental confirmation. Daptomycin's complex structure and biosynthesis have hampered the analysis of its structure activity relationships. Novel methods of total synthesis, including a recent one that is carried out entirely on a solid phase, will enable a more thorough and systematic exploration of the sequence space.

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“…above) is considered to function as a sensor for coordination of membrane protein synthesis and phospholipid formation in E. coli (74). It has been established recently that plus-charged proteins and peptides can bind and thereby withdraw the minus-charged phospholipids PG and CL from the free pool in a bilayer (59,75). By binding to PG (and CL), the many alMGS molecules may withdraw these lipids laterally from the bilayer; alMGS and its binding helix have an established binding capacity for and potential sequestration of PG and CL (45).…”

Section: Formation Of Intracellular Membranesmentioning

confidence: 99%

Massive Formation of Intracellular Membrane Vesicles in Escherichia coli by a Monotopic Membrane-bound Lipid Glycosyltransferase

Eriksson

Wessman

et al. 2009

Journal of Biological Chemistry

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The morphology and curvature of biological bilayers are determined by the packing shapes and interactions of their participant molecules. Bacteria, except photosynthetic groups, usually lack intracellular membrane organelles. Strong overexpression in Escherichia coli of a foreign monotopic glycosyltransferase (named monoglycosyldiacylglycerol synthase), synthesizing a nonbilayer-prone glucolipid, induced massive formation of membrane vesicles in the cytoplasm. Vesicle assemblies were visualized in cytoplasmic zones by fluorescence microscopy. These have a very low buoyant density, substantially different from inner membranes, with a lipid content of >60% (w/w). Cryo-transmission electron microscopy revealed cells to be filled with membrane vesicles of various sizes and shapes, which when released were mostly spherical (diameter ≈100 nm). The protein repertoire was similar in vesicle and inner membranes and dominated by the glycosyltransferase. Membrane polar lipid composition was similar too, including the foreign glucolipid. A related glycosyltransferase and an inactive monoglycosyldiacylglycerol synthase mutant also yielded membrane vesicles, but without glucolipid synthesis, strongly indicating that vesiculation is induced by the protein itself. The high capacity for membrane vesicle formation seems inherent in the glycosyltransferase structure, and it depends on the following: (i) lateral expansion of the inner monolayer by interface binding of many molecules; (ii) membrane expansion through stimulation of phospholipid synthesis, by electrostatic binding and sequestration of anionic lipids; (iii) bilayer bending by the packing shape of excess nonbilayer-prone phospholipid or glucolipid; and (iv) potentially also the shape or penetration profile of the glycosyltransferase binding surface. These features seem to apply to several other proteins able to achieve an analogous membrane expansion.

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Bacterial Membranes as Predictors of Antimicrobial Potency

Cited by 161 publications

References 35 publications

Membrane interaction of a new synthetic antimicrobial lipopeptide sp-85 with broad spectrum activity

Membrane interaction of a new synthetic antimicrobial lipopeptide sp-85 with broad spectrum activity

The action mechanism of daptomycin

Massive Formation of Intracellular Membrane Vesicles in Escherichia coli by a Monotopic Membrane-bound Lipid Glycosyltransferase

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