Automated Modeling and Validation of Protein Complexes in Cryo-EM Maps

The resolving power of cryo-EM experiments has dramatically improved in recent years. However, many cryo-EM maps may still not achieve a resolution that is sufficiently high to allow model building directly from the map. Instead, it is common practice to fit an initial atomic model to the map and refine this model. Depending on the resolution and whether the structure suffers from inherent flexibility or experimental limitations, different methods can be applied, to obtain high-quality, well-fitted atomic model of the macromolecular assembly represented by the map, and to assess its properties. In this review, we describe some of these methods, with the main focus on those that have been developed in our group over the last decade.