Near-atomic resolution reconstructions using a mid-range electron microscope operated at 200 kV

Area of Science:

• Structural Biology
• Biophysics
• Microscopy

Background:

• Single particle cryo-electron microscopy (cryoEM) has advanced significantly, approaching X-ray crystallography resolution for protein structure determination.
• Direct electron detectors have revolutionized cryoEM, enabling near-atomic resolution reconstructions.
• Historically, high-resolution cryoEM has been limited to high-end, specialized microscopes.

Purpose of the Study:

• To demonstrate that widely available mid-range electron microscopes, when equipped with new direct detectors, can achieve high-resolution cryoEM reconstructions.
• To show that these reconstructions are suitable for de novo protein structure modeling.
• To outline the strategy for obtaining high-resolution cryoEM maps.

Main Methods:

• Utilized a widely used mid-range electron microscope integrated with a new generation of direct electron detectors.
• Applied a specific strategy for data collection and image processing.
• Focused on achieving high signal-to-noise ratios in cryoEM data.

Main Results:

• Achieved a 3.7 Å resolution cryoEM reconstruction of Nudaurelia capensis ω virus.
• Obtained a 4.2 Å resolution cryoEM reconstruction of the Thermoplasma acidophilum T20S proteasome.
• Demonstrated the capability for de novo modeling of protein structures from these reconstructions.

Conclusions:

• High-resolution cryoEM structure determination is now accessible with mid-range electron microscopes and advanced direct detectors.
• This technological combination democratizes high-resolution structural biology, expanding its application.
• The findings pave the way for broader adoption of cryoEM in protein structure research.