Overcoming Resolution Attenuation During Tilted Cryo-EM Data Collection.

Area of Science:

• Structural Biology
• Biophysics
• Biochemistry

Background:

• Preferred specimen orientation in cryo-electron microscopy (cryo-EM) leads to anisotropic maps and hinders accurate 3D structure determination.
• Specimen stage tilting is a known strategy to mitigate preferred orientations, but often causes significant resolution loss.

Approach:

• Developed updated cryo-EM data collection and image processing workflows to address resolution attenuation during stage tilting.
• Validated the new workflows across multiple biological specimens, including a bacterial RNA polymerase.
• Achieved high-resolution (3 Å) reconstruction of a challenging specimen with preferred orientation.

Key Points:

• Resolution attenuation associated with stage tilting is negligible or substantially reduced with the new workflows.
• Cryo-EM reconstructions are virtually indistinguishable whether the stage is tilted up to 60° or not.
• A quantitative framework is provided to help cryo-EM users determine optimal tilt angles for data acquisition.

Conclusions:

• Employing stage tilt during cryo-EM data collection is a highly effective strategy for obtaining isotropic maps.
• The developed methods and quantitative framework enhance the utility of stage tilting for robust cryo-EM structure determination.
• This approach facilitates high-resolution structural analysis of specimens previously limited by preferred orientation artifacts.