title: Direct electron detection yields cryo-EM reconstructions at resolutions beyond 3/4 Nyquist frequency.
abstract: One limitation in electron cryo-microscopy (cryo-EM) is the inability to recover high-resolution signal from the image-recording media at the full-resolution limit of the transmission electron microscope. Direct electron detection using CMOS-based sensors for digitally recording images has the potential to alleviate this shortcoming. Here, we report a practical performance evaluation of a Direct Detection Device (DDD®) for biological cryo-EM at two different microscope voltages: 200 and 300 kV. Our DDD images of amorphous and graphitized carbon show strong per-pixel contrast with image resolution near the theoretical sampling limit of the data. Single-particle reconstructions of two frozen-hydrated bacteriophages, P22 and ε15, establish that the DDD is capable of recording usable signal for 3D reconstructions at about 4/5 of the Nyquist frequency, which is a vast improvement over the performance of conventional imaging media. We anticipate the unparalleled performance of this digital recording device will dramatically benefit cryo-EM for routine tomographic and single-particle structural determination of biological specimens.
authors.affiliation: Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Bammes
authors.forename: Ryan H
authors.initials: RH
authors.lastname: Rochat
authors.forename: Joanita
authors.initials: J
authors.lastname: Jakana
authors.forename: Dong-Hua
authors.initials: DH
authors.lastname: Chen
authors.forename: Wah
authors.initials: W
authors.lastname: Chiu
mesh_terms: D001435:Bacteriophages / Q000648:ultrastructure; D020285:Cryoelectron Microscopy / Q000379:methods*; D007091:Image Processing, Computer-Assisted