(526c) Three-Dimensional Electron Crystallography of Protein Microcrystals

X-ray crystallography has been an enormously successful tool for the determination of high-resolution protein structures. However, the growth of large well-ordered protein crystals necessary for diffraction experiments still remains a major hurdle.  Because of this, techniques that can provide structural information from very small microcrystals are extremely desirable. We demonstrate that it is feasible to determine high-resolution protein structures by electron crystallography of three-dimensional microcrystals in an electron cryo-microscope (CryoEM); a technique we call MicroED. Lysozyme microcrystals were frozen on an electron microscopy grid, and electron diffraction data collected to 1.7Å resolution. We indexed the data from three crystals and used them for structure determination of lysozyme by molecular replacement followed by crystallographic refinement to 2.9Å resolution. In this presentation I will present our initial proof of principle study and highlight the major advances since the initial publication.