Functional Nanomembranes for High-Resolution Electron Cryo-Microscopy of Biological Samples

• Applicants: Professor Dr. Andreas Terfort, since 9/2017; Professor Dr. Andrey Turchanin
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry ; Solid State and Surface Chemistry, Material Synthesis ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 255210654

Transmission electron cryo-microscopy (cryoEM) of vitrified biological specimens is a powerful tool for structural biology. However, current preparation of vitrified biological samples has drawbacks hampering high-resolution cryoEM, as it suffers (a) from poor electrical and mechanical properties of the freestanding layer of amorphous ice, in which biomolecules (e.g., proteins) are embedded; (b) from low protein expression rates; and (c) difficulties with the purification of sensitive biomolecules. In this project we want to develop functional ultrathin (~1-5 nm) organic nanomembranes to solve these fundamental problems. The developed nanomembranes will possess (i) specific bio-recognition sites for selective binding of the desired biomolecules; (ii) good electrical conductivity at cryogenic temperatures to mitigate beam-induced electrostatic charges; and (iii) high mechanical stability as free-standing sheets stabilizing vitrified samples. With these novel support films we will achieve both an increase in the resolution routinely achieved with ice-embedded specimens and direct purification of biomolecules from heterogeneous mixtures for cryoEM. To fabricate and characterize these advanced cryoEM nanomembranes, we will apply a combination of interdisciplinary state-of-the-art methods including spectroscopy/microscopy techniques of solid-state physics, methods of synthetic chemistry, and biological electron microscopy. The ultimate goal of this project is to enable routine use of the developed functional nanomembranes for in situ separation/isolation and subsequent structural analysis of unknown biological samples by high-resolution cryoEM. Furthermore, we plan to use functional nanomembranes for 2D crystallization and structural analysis of membrane proteins, which do not readily form 2D crystals sufficient for high-resolution cryoEM. We expect that the suggested approach will facilitate further developments in structural biology by improving the capabilities of cryoEM through simplified sample preparation as well as pushing the achievable resolution to unprecedented limits.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr. Daniel Rhinow, until 8/2017