High-resolution cryo-EM reconstructions in the presence of substantial aberrations

IUCrJ. 2020 Mar 26;7(Pt 3):445-452. doi: 10.1107/S2052252520002444. eCollection 2020 May 1.


Here, an analysis is performed of how uncorrected antisymmetric aberrations, such as coma and trefoil, affect cryo-EM single-particle reconstruction (SPR) results, and an analytical formula quantifying information loss owing to their presence is inferred that explains why Fourier-shell coefficient-based statistics may report significantly overestimated resolution if these aberrations are not fully corrected. The analysis is validated with reference-based aberration refinement for two cryo-EM SPR data sets acquired with a 200 kV microscope in the presence of coma exceeding 40 µm, and 2.3 and 2.7 Å reconstructions for 144 and 173 kDa particles, respectively, were obtained. The results provide a description of an efficient approach for assessing information loss in cryo-EM SPR data acquired in the presence of higher order aberrations, and address inconsistent guidelines regarding the level of aberrations that is acceptable in cryo-EM SPR experiments.

Keywords: 3D reconstruction and image processing; automation; axial aberrations; coma; cryo-EM; imaging; resolution; single-particle cryo-EM; structure determination; trefoil; validation.