Atomic force microscopy of supported lipid bilayers

Mingeot-Leclercq, Marie Paule; Deleu, Magali; Brasseur, Robert; Dufrêne, Yves F.

doi:10.1038/nprot.2008.149

Cited by 200 publications

(183 citation statements)

References 40 publications

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“…For these tests, alamethicin was selected as the positive control due to its well-established in vitro pore-forming capabilities. Atomic force microscopy (AFM) (49) revealed that alamethicin induced deformation of membranes at 10 μM, similar to what has been described (50). In contrast, membranes treated with 10 μM of 1 were indistinguishable from untreated control membranes (Fig.…”

supporting

confidence: 80%

Unique amalgamation of primary and secondary structural elements transform peptaibols into potent bioactive cell-penetrating peptides

Risinger²,

Mitchell

et al. 2017

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

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Mass-spectrometry-based metabolomics and molecular phylogeny data were used to identify a metabolically prolific strain of Tolypocladium that was obtained from a deep-water Great Lakes sediment sample. An investigation of the isolate's secondary metabolome resulted in the purification of a 22-mer peptaibol, gichigamin A (1). This peptidic natural product exhibited an amino acid sequence including several β-alanines that occurred in a repeating ααβ motif, causing the compound to adopt a unique right-handed 3 11 helical structure. The unusual secondary structure of 1 was confirmed by spectroscopic approaches including solution NMR, electronic circular dichroism (ECD), and single-crystal X-ray diffraction analyses. Artificial and cell-based membrane permeability assays provided evidence that the unusual combination of structural features in gichigamins conferred on them an ability to penetrate the outer membranes of mammalian cells. Compound 1 exhibited potent in vitro cytotoxicity (GI 50 0.55 ± 0.04 μM) and in vivo antitumor effects in a MIA PaCa-2 xenograft mouse model. While the primary mechanism of cytotoxicity for 1 was consistent with ion leakage, we found that it was also able to directly depolarize mitochondria. Semisynthetic modification of 1 provided several analogs, including a C-terminus-linked coumarin derivative (22) that exhibited appreciably increased potency (GI 50 5.4 ± 0.1 nM), but lacked ion leakage capabilities associated with a majority of naturally occurring peptaibols such as alamethicin. Compound 22 was found to enter intact cells and induced cell death in a process that was preceded by mitochondrial depolarization.peptaibol | fungi | natural products | gichigamin | mitochondria N atural product chemical research has evolved in many extraordinary ways over the last decade largely due to the integration of powerful and accessible analytical chemistry (1, 2) and molecular biology (3, 4) tools. Some of these techniques have been applied toward the creation of natural product big-data sets in which genomic, metagenomic, metabolomic, and proteomic approaches are combined to obtain new insights into nature's remarkable chemical bounty (4-8). The predictive capabilities of these methods have helped guide efforts in several fertile areas of natural products research including the DNA cross-linking enediynes (9), bioactive cyanobacterial metabolites (10, 11), cytotoxic pentangular polyphenols (12), and thiopeptide antibiotics (13).The integration of analytical and molecular approaches is an effective way to find new natural product analogs that exhibit enhanced biological activities and improved pharmacological attributes (e.g., greater potency, better solubility, enhanced therapeutic index, etc.), but it also has the potential to uncover compounds with activities that are markedly dissimilar to other members of the queried chemical class. Nature is well known for its chemical repurposing capabilities, which allow populations of organisms to evolve new biological functions from existing molecular sc...

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supporting

confidence: 80%

Unique amalgamation of primary and secondary structural elements transform peptaibols into potent bioactive cell-penetrating peptides

Risinger²,

Mitchell

et al. 2017

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

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“…S2) (25). A comparative analysis was performed on SLBs prepared by the surface deposition of AUV in aqueous solution using adapted protocols (26,29). Silicon wafers used as substrates were coated with a 9-nm layer of silicon dioxide to (i) support homogeneous and stable bilayers maintained in the fluid phase at room temperature and (ii) avoid charge build-up during SIMS measurements, which is necessary as SIMS relies on the detection of secondary ions extracted from the surface by a focused beam of primary ions ( 133 Cs + ) rastered across the sample (29).…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, longer time and length scale studies are accessible in supported lipid bilayers (SLBs) (26). SLBs provide ideal experimental models for fluid-phase membranes and can be imaged by atomic force microscopy (AFM) (27,28).…”

mentioning

confidence: 99%

Nanoscale imaging reveals laterally expanding antimicrobial pores in lipid bilayers

Rakowska

Jiang

Ray

et al. 2013

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

117

155

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Antimicrobial peptides are postulated to disrupt microbial phospholipid membranes. The prevailing molecular model is based on the formation of stable or transient pores although the direct observation of the fundamental processes is lacking. By combining rational peptide design with topographical (atomic force microscopy) and chemical (nanoscale secondary ion mass spectrometry) imaging on the same samples, we show that pores formed by antimicrobial peptides in supported lipid bilayers are not necessarily limited to a particular diameter, nor they are transient, but can expand laterally at the nano-to-micrometer scale to the point of complete membrane disintegration. The results offer a mechanistic basis for membrane poration as a generic physicochemical process of cooperative and continuous peptide recruitment in the available phospholipid matrix.innate host defense | de novo protein design | nanometrology | antibiotics | nanoscopy

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“…To characterize the interaction of AH peptide with the intact vesicle platform, QCM-D monitoring and atomic force microscopy (AFM) were employed as complementary techniques to respectively probe the interaction kinetics and morphological changes [82,88]. The adsorption of lipid vesicles onto solid supports results in the selfassembly of different lipid structures.…”

Section: Vesicle-to-bilayer Structural Transformation By Ah Peptidementioning

confidence: 99%

Model Membrane Platforms for Biomedicine: Case Study on Antiviral Drug Development

Jackman

Cho

2012

Biointerphases

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As one of the most important interfaces in cellular systems, biological membranes have essential functions in many activities such as cellular protection and signaling. Beyond their direct functions, they also serve as scaffolds to support the association of proteins involved in structural support, adhesion, and transport. Unfortunately, biological processes sometimes malfunction and require therapeutic intervention. For those processes which occur within or upon membranes, it is oftentimes difficult to study the mechanism in a biologically relevant, membranous environment. Therefore, the identification of direct therapeutic targets is challenging. In order to overcome this barrier, engineering strategies offer a new approach to interrogate biological activities at membrane interfaces by analyzing them through the principles of the interfacial sciences. Since membranes are complex biological interfaces, the development of simplified model systems which mimic important properties of membranes can enable fundamental characterization of interaction parameters for such processes. We have selected the hepatitis C virus (HCV) as a model viral pathogen to demonstrate how model membrane platforms can aid antiviral drug discovery and development. Responsible for generating the genomic diversity that makes treating HCV infection so difficult, viral replication represents an ideal step in the virus life cycle for therapeutic intervention. To target HCV genome replication, the interaction of viral proteins with model membrane platforms has served as a useful strategy for target identification and characterization. In this review article, we demonstrate how engineering approaches have led to the discovery of a new functional activity encoded within the HCV nonstructural 5A protein. Specifically, its N-terminal amphipathic, α-helix (AH) can rupture lipid vesicles in a size-dependent manner. While this activity has a number of exciting biotechnology and biomedical applications, arguably the most promising one is in antiviral medicine. Based on the similarities between lipid vesicles and the lipid envelopes of virus particles, experimental findings from model membrane platforms led to the prediction that a range of medically important viruses might be susceptible to rupturing treatment with synthetic AH peptide. This hypothesis was tested and validated by molecular virology studies. Broad-spectrum antiviral activity of the AH peptide has been identified against HCV, HIV, herpes simplex virus, and dengue virus, and many more deadly pathogens. As a result, the AH peptide is the first in class of broad-spectrum, lipid envelope-rupturing antiviral agents, and has entered the drug pipeline. In summary, engineering strategies break down complex biological systems into simplified biomimetic models that recapitulate the most important parameters. This approach is particularly advantageous for membrane-associated biological processes because model membrane platforms provide more direct characterization of target interactions than is possible with other methods. Consequently, model membrane platforms hold great promise for solving important biomedical problems and speeding up the translation of biological knowledge into clinical applications.

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Atomic force microscopy of supported lipid bilayers

Cited by 200 publications

References 40 publications

Unique amalgamation of primary and secondary structural elements transform peptaibols into potent bioactive cell-penetrating peptides

Unique amalgamation of primary and secondary structural elements transform peptaibols into potent bioactive cell-penetrating peptides

Nanoscale imaging reveals laterally expanding antimicrobial pores in lipid bilayers

Model Membrane Platforms for Biomedicine: Case Study on Antiviral Drug Development

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