Likelihood‐based interactive local docking into cryo‐EM maps in ChimeraX.

The interpretation of cryo‐EM maps often includes the docking of known or predicted structures of the components, which is particularly useful when the map resolution is worse than 4 Å. Although it can be effective to search the entire map to find the best placement of a component, the process can be slow when the maps are large. However, frequently there is a well‐founded hypothesis about where particular components are located. In such cases, a local search using a map subvolume will be much faster because the search volume is smaller, and more sensitive because optimizing the search volume for the rotation‐search step enhances the signal to noise. A Fourier‐space likelihood‐based local search approach, based on the previously published em_placement software, has been implemented in the new emplace_local program. Tests confirm that the local search approach enhances the speed and sensitivity of the computations. An interactive graphical interface in the ChimeraX molecular‐graphics program provides a convenient way to set up and evaluate docking calculations, particularly in defining the part of the map into which the components should be placed. [ABSTRACT FROM AUTHOR]