ZART: A Novel Multiresolution Reconstruction Algorithm with Motion-blur Correction for Single Particle Analysis

One of the main purposes of CryoEM Single Particle Analysis is to reconstruct the three-dimensional structure of a macromolecule thanks to the acquisition of many particle images representing different poses of the sample. By estimating the orientation of each projected particle, it is possible to recover the underlying 3D volume by multiple 3D reconstruction methods, usually working either in Fourier or in real space. However, the reconstruction from the projected images works under the assumption that all particles in the dataset correspond to the same conformation of the macromolecule. Although this requi-site holds for some macromolecules, it is not true for flexible specimens, leading to motion-induced arte-facts in the reconstructed CryoEM maps. In this work, we introduce a new Algebraic Reconstruction Technique called ZART, which is able to include continuous flexibility information during the reconstruc-tion process to improve local resolution and reduce motion blurring. The conformational changes are mod-elled through Zernike3D polynomials. Our implementation allows for a multiresolution description of the macromolecule adapting itself to the local resolution of the reconstructed map. In addition, ZART has also proven to be a useful algorithm in cases where flexibility is not so dominant, as it improves the overall aspect of the reconstructed maps by improving their local and global resolution.(c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://crea-tivecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The main purpose of CryoEM Single Particle Analysis is to reconstruct the three-dimensional structure of a macromolecule. ZART is a new Algebraic Reconstruction Technique that can include continuous flexibility information to improve resolution and reduce motion blurring.