Current approaches for automated model building into cryo-EM maps using Buccaneer with CCP-EM

Area of Science:

• Structural biology
• Biophysics
• Computational biology

Background:

• Electron cryo-microscopy (cryo-EM) is a powerful technique for determining protein structures.
• Protein model building is a crucial step in cryo-EM data analysis.
• Buccaneer is a software tool traditionally used for X-ray crystallography model building.

Purpose of the Study:

• To adapt and optimize the Buccaneer software for structural interpretation of cryo-EM maps.
• To demonstrate the effectiveness of Buccaneer when applied to cryo-EM data.
• To improve the protein model building process in cryo-EM.

Main Methods:

• Utilizing the existing Buccaneer software.
• Optimizing Buccaneer settings specifically for cryo-EM maps.
• Integrating Buccaneer into the CCP-EM software interface (version 1.4.0 and later).
• Applying the optimized pipeline to 208 cryo-EM datasets with resolutions better than 4 Å.

Main Results:

• Successful application of Buccaneer to a large dataset of cryo-EM maps.
• Demonstrated improvement in the protein sequencing step by replacing crystallographic references with cryo-EM references.
• Validation of the optimized Buccaneer workflow for cryo-EM map interpretation.

Conclusions:

• Buccaneer can be effectively optimized for protein model building using cryo-EM maps.
• Replacing crystallographic references with cryo-EM references significantly improves structural interpretation.
• The integration within CCP-EM provides a streamlined pipeline for cryo-EM model building.