Consensus among flexible fitting approaches improves the interpretation of cryo-EM data.

Area of Science:

• Structural biology
• Biophysics
• Computational biology

Background:

• Cryo-electron microscopy (cryo-EM) reveals large macromolecular assemblies in various states.
• Fitting high-resolution structures into low-resolution cryo-EM maps is common practice.
• Rigid domain fitting (RDF) is a standard method for modeling conformational changes.

Purpose of the Study:

• To compare and evaluate different automated flexible fitting protocols.
• To assess the convergence and reliability of flexible fitting approaches against RDF models.
• To enhance the interpretation of cryo-EM data and structural modeling.

Main Methods:

• Applied three diverse automated flexible fitting approaches to a protein dataset.
• Compared flexible fitting results with existing rigid domain fitting (RDF) models in the Protein Data Bank (PDB).
• Analyzed conformational consensus and discrepancies among different fitting strategies.

Main Results:

• A general consensus in conformations was observed across different flexible fitting methods.
• Convergence was not always achieved for proteins with complex conformational changes or missing cryo-EM densities.
• RDF models in the PDB sometimes differed significantly from flexible fitting consensus and X-ray structures.

Conclusions:

• A consensus from multiple automated flexible fitting approaches increases confidence in modeled configurations.
• This protocol improves the interpretation of cryo-EM data by highlighting regions with uncertain fitting.
• Flexible fitting consensus offers a more reliable representation of protein conformations compared to isolated RDF models.