Structure Determination by Single Particle Cryo‐electron Tomography

Abstract

Abstract Cryo‐electron Tomography (CET) is a method to image macromolecular assemblies three‐dimensionally in their native settings. Averaging of subtomograms, each containing a copy of a macromolecule of interest, offers substantially higher resolution insights into these macromolecules than CET alone. Here, we give an account of recent methodological advances in subtomogram averaging and approaches to capture structural heterogeneity of macromolecular complexes. Using these methods intermediate resolution insights (15–30 Å) into various membrane‐associated complexes and transient interactions between individual complexes in their physiological environment could be obtained. With further advances in hard‐ and software looming subtomogram analysis will play an increasingly important role in structural biology. Key Concepts: Cryo‐electron tomography images macromolecules in their physiological environment in 3D. Averaging subtomograms depicting a macromolecular complex of interest yields higher resolution maps. Subtomogram alignment and averaging is an optimisation problem. Classification of subtomograms may separate different conformers in heterogeneous datasets and reveal corresponding densities. Membrane‐associated complexes can be studied in their native membrane ( in situ ). Transient interactions can be revealed from tomograms of whole cells and lysates.