High-resolution structure determination by continuous rotation data collection in MicroED

These authors contributed equally to this work. MicroED uses very small three-dimensional protein crystals and electron diffraction for structure determination. An improved data collection protocol for MicroED called “continuous rotation ” is presented. Here microcrystals are continuously rotated during data collection yielding improved data, and allowing data processing with MOSFLM resulting in improved resolution for the model protein lysozyme. These improvements pave the way for the implementation and application of MicroED with wide applicability in structural biology. Producing large well-ordered crystals is a major bottleneck for protein structure determination by X-ray crystallography. Because large crystals are needed to withstand the negative effects of radiation damage during data collection, small micro and nanocrystals have generally been ignored and cast aside as unusable. Many difficult to crystallize targets never reach a usable size and are generally discarded; therefore methods that can facilitate structure determination from these small crystals would be exceedingly valuable. Advances with X-ray free-electron lasers (XFEL) have made it possible to use microcrystals to solv