Membrane Protein Structure Determination using Atom Probe Tomography

Research Project, 2020 – 2024

In this project, a fundamentally new method for determining membrane protein structures will be developed. The method has the power to simultaneously determine the 3D structure and elemental composition of individual proteins in complex environments, such as their native cell membranes, with near atomic resolution.The technique is based on the atom probe tomography (APT) technique, which is spatially resolved mass spectrometry, and will through its high accuracy and unique signal acquisition constitute a fundamentally new approach for protein analysis. The analysis is performed on samples shaped as ultra-sharp nanostructured needles from which ionized atoms are peeled off, atom-by-atom, in an electrical field under photonic irradiation. The collected data is then reconstructed, resolving the position of each atom in 3D. One novelty of the proposed project is the approach to exchange the water in the sample with an amorphous oxide, while still preserving the protein in its native state. Such a protein immobilization strategy has earlier been shown to retain both protein structure and function, but has not been combined with APT before.The specific aim will be towards direct 3D visualization and chemical composition analysis of membrane proteins when situated within membranes in a “true single-particle approach”. A successful outcome of the project may thus allow for a paradigm shift in the field of membrane protein structure determination.