Towards a Protein-Size Dependent Resolution Limit due to Dynamical Scattering in Cryo-transmission Electron...

Area of Science:

• Structural biology
• Electron microscopy

Background:

• Single-particle reconstruction in cryo-transmission electron microscopy relies on the weak phase object approximation.
• Understanding the impact of scattering assumptions on resolution is crucial for accurate structural determination.

Purpose of the Study:

• To systematically assess how scattering assumptions limit resolution in cryo-transmission electron microscopy.
• To compare theoretical resolution limits with experimental observations and benchmarks.
• To investigate the influence of protein thickness and scattering models on attainable resolution.

Main Methods:

• Simulations of eight protein complexes (up to 97.5 nm thick) using single-, multislice, and hybrid scattering models.
• Utilizing molecular dynamics for amorphous ice embedding.
• Assessing model reliability using multislice scattering as a reference in real and Fourier space, including Fourier ring correlations.
• Comparing simulation results with literature resolutions.

Main Results:

• Attainable resolution is proportional to the square root of the projection thickness.
• Results show quantitative agreement with high-resolution experimental data for proteins of significant size.
• Identified efficient methods for approximating multiple scattering in thick protein samples.

Conclusions:

• Provides a theoretical framework for predicting resolution based on protein size and thickness.
• Highlights the importance of accurate scattering models for achieving high resolution.
• Discusses the impact of ice background noise and optimal ice thickness for different protein sizes.