News

Starting with the first crystal structures that were determined in the 1950s, structural biology has evolved in nearly one century with enormous technology revolutions including synchrotron radiation facilities, electron crystallography, nuclear magnetic resonance, membrane protein crystallization, molecular dynamics simulations, cryo-electron microscopy, and very recently, deep-learning protein structure predictions. This enables us to study macromolecular structures from simple to complex, from small to huge, from soluble to membrane bound, and from static to dynamic. With the recent rapid advances in electron microscopy techniques among them cryo-electron tomography (cryo-ET), fluorescence-guided cryo-focused ion beam (cryo-FIB), cryo-scanning transmission electron tomography (cryo-STET), cryo-ptychography (cryo-TYCHO), and cryo-ultrafast electron microscopy (cryo-UEM), a shift occurs from in vitro to in situ structural biology, and from spatial to temporal-spatial resolution. The current bottlenecks of in situ cryo-ET workflows include difficulties in preparing cryo-lamella of tissue specimen at the target region, the limited throughput of data collection, the limited power of current algorithms to detect structural heterogeneity, and the bottom limitation of macromolecular size, among others. These obstacles will be resolved in the coming years. The in situ structures of many supra macromolecular compartments, e.g., centrosome, axoneme, kinetochore, and the synaptonemal complex are already being studied at near-atomic resolution. The further development of cryo-STET and cryo-TYCHO will break the thickness limitation of cryo-ET and potentially re-shape the current workflow of in situ structural studies. The damage of cryo-lamella during cryo-FIB will be quantitatively investigated and efficiently reduced with hardware innovations. Cryo-UEM could potentially reduce the electron radiation damage of macromolecules and thus allow a higher dose illumination to improve the signal-noise ratio of tomography data. Besides, the pump-and-probe mode of cryo-UEM opens the possibility of studying light induced ultra-fast (ps ∼ μs) processes of many macromolecules such as fluorescence proteins and light-harvesting complexes. A new era is just on the road.

Link: The next decade in structural biology