High-Speed Atomic Force Microscopy of Protein-Protein Interactions

Protein-protein interactions are of major importance for biological function. Many proteins are oligomers and interact temporaly with other proteins. This is of particular importance in the membrane, where multiprotein assemblies act in important processes like signaling, respiration, photosynthesis, etc. High-speed atomic force microscopy (HS-AFM,[1]) offers unique possibilities to study protein-protein interactions in the membrane. HS-AFM allows not only visualization and tracking of single proteins but also their environment, hence describing the interaction energy between proteins (Fig.1A,[2]), their dynamic supramolecular assemblies (Fig.1B,[3]), and membrane crowding and interaction specificity (Fig.1C, [4]). The interaction profiles can be, though at different time scales, compared to molecular simulations [4]. The perspective of short-cantilever HS-AFM in force spectroscopy will be discussed: the high speed of short cantilevers allows measuring interaction forces at unprecedented loading rates and temporal resolution (Fig.1D).References[1] Ando, PNAS 98 (22):12468-12472 (2001).[2] Casuso, BiophysJ 99 (7):47-49 (2010).[3] Colom, JMB 423 (2):249-256 (2012)[4] Casuso, Nat Nanotechnol 7 (8):525-529 (2012).Fig. 1) Membrane protein interactions by HS-AFM. (a) Dimer interaction of ATP-synthase c-rings, (b) AQP0 array association/dissociation in eye lens membranes, (c) OmpF diffusion and interactions, (d) HS-AFM based force spectrocopy at 1MHz temporal resolution.View Large Image | View Hi-Res Image | Download PowerPoint Slide