Probing peptide–membrane interactions using AFM

Abstract

Atomic force microscopy (AFM) has become a powerful addition to the range of instruments available to probe the organization of lipid monolayers and bilayers. Currently, AFM is the only tool that can provide nanoscale topographic images of supported lipid membranes under physiological conditions, enabling researchers to resolve their detailed structure and to monitor their interaction with drugs, peptides and proteins. Here, we survey recent data obtained by our research groups that demonstrate the power of the technique for exploring peptide-membrane interactions, with an emphasis on microbial lipopeptides and on tilted peptides.

Label-free characterization of biomembranes: from structure to dynamics

“…They reported in-plane resolutions better than 0.5 nm. [46][47][48][49][50][51][52] Depth resolution in AFM is limited by thermal fluctuations of the cantilever. 53 This work later led to research on native membranescomplex non-crystalline lipid/protein assemblies -where the dynamics of single transmembrane protein molecules could be observed.…”

Peptide-Induced Domain Formation in Supported Lipid Bilayers: Direct Evidence By Combined Atomic Force and Polarized Total Internal Reflection Fluorescence Microscopy

“…In brief, the AFM raster-scans over the upper surface of the SPB, generating a topographical image with subnanometer vertical resolution and nanometer lateral resolution. Depending on the bilayer composition and imaging conditions, lipid domains may be resolved as local variations in bilayer thickness arising from differences in acyl-chain packing (66)(67)(68)(69)(70)(71). In pTIRFM, a polarized beam of light is directed through the periphery of a high-numerical-aperture microscope objective lens such that the beam undergoes total internal reflection at the substrate-sample solution interface.…”

In situ molecular level studies on membrane related peptides and proteins in real time using sum frequency generation vibrational spectroscopy

“…Neutron reflection studies have also permitted the determination of the amount of adsorbed peptides/proteins (Fragneto-Cusani, 2001; Haas et al, 2007; Kučerka et al, 2007). Atomic force microscopy techniques, on the other hand, are very useful in studying the packing and surface ordering of membrane-bound proteins (Alessandrini et al, 2005; Brasseur et al, 2008; Engel et al, 2008; Johnston, 2007; Laflamme et al, 2008; Richter et al, 2006). Ellipsometry, in contrast, can be utilized to follow proteins’ adsorption kinetics onto membranes and determine the adsorbed protein film thickness (Faiss et al, 2008).…”