Escaping the symmetry trap in helical reconstruction. (5th August 2022) - Gambelli, Lavinia
Abstract : In this study, we reflect on widely-used helical processing routines in cryoEM and suggest a new workflow capable of uncovering heterogeneities and complex symmetries that could otherwise be overlooked. Abstract : Helical reconstruction is the method of choice for obtaining 3D structures of filaments from electron cryo-microscopy (cryoEM) projections. This approach relies on applying helical symmetry parameters deduced from Fourier–Bessel or real space analysis, such as sub-tomogram averaging. While helical reconstruction continues to provide invaluable structural insights into filaments, its inherent dependence on imposing a pre-defined helical symmetry can also introduce bias. The applied helical symmetry produces structures that are infinitely straight along the filament's axis and can average out biologically important heterogeneities. Here, we describe a simple workflow aimed at overcoming these drawbacks in order to provide truer representations of filamentous structures.