High-Resolution Tomography, Molecular Model Building and Visualization

A long sought-after goal in cellular biology is to be able to visualize macromolecular complexes inside cells at resolutions that are sufficient to characterize molecular level interactions. While cryo-electron tomography (ET) is uniquely positioned to address this challenge, numerous technical bottlenecks in data collection and image processing exist that have slowed down progress toward achieving this goal. This chapter describes the main challenges in high-resolution cryo-ET imaging and presents effective strategies to accelerate the collection of high-quality tilt-series, data-driven methods to efficiently extract high-resolution information from the raw data, strategies for tomogram segmentation and visualization, and techniques for atomic model building and integrative modeling of multi-component complexes imaged by cryo-ET. While challenges still remain in all these areas, this technology can already produce de novo atomic models of proteins in their native state, indicating that cryo-ET is on a trajectory to become an effective technique for visualizing cell interiors at unprecedented levels of detail.