Separating distinct structures of multiple macromolecular assemblies from cryo-EM projections

Eric J. Verbeke, Yi Zhou, Andrew P. Horton, Anna L. Mallam, David W. Taylor, Edward M. Marcotte
2019 Journal of Structural Biology  
Single particle analysis for structure determination in cryo-electron microscopy is traditionally applied to samples purified to near homogeneity as current reconstruction algorithms are not designed to handle heterogeneous mixtures of structures from many distinct macromolecular complexes. We extend on long established methods and demonstrate that relating two-dimensional projection images by their common lines in a graphical framework is sufficient for partitioning distinct protein and
more » ... otein complexes within the same data set. The feasibility of this approach is first demonstrated on a large set of synthetic reprojections from 35 unique macromolecular structures spanning a mass range of hundreds to thousands of kilodaltons. We then apply our algorithm on cryo-EM data collected from a mixture of five protein complexes and use existing methods to solve multiple three-dimensional structures ab initio. Incorporating methods to sort single particle cryo-EM data from extremely heterogeneous mixtures will alleviate the need for stringent purification and pave the way toward investigation of samples containing many unique structures.
doi:10.1016/j.jsb.2019.107416 pmid:31726096 pmcid:PMC6952565 fatcat:spg2sfvoxnb4nekr4dkdleve7e