ChemEM: Flexible Docking of Small Molecules in Cryo-EM Structures

Area of Science:

• Structural Biology
• Computational Chemistry
• Drug Discovery

Background:

• Cryo-electron microscopy (cryo-EM) is crucial for structure-based drug discovery.
• Medium-resolution cryo-EM data (3-4 Å) present challenges for precise ligand and side-chain positioning.
• Accurate small-molecule docking is essential for virtual screening and drug design.

Purpose of the Study:

• To introduce ChemEM, a novel software package for accurate ligand docking in protein-binding sites using cryo-EM data.
• To evaluate ChemEM's performance against established methods and experimental data.
• To demonstrate the utility of medium-resolution cryo-EM maps in drug discovery.

Main Methods:

• Development of ChemEM software for ligand docking utilizing cryo-EM structural data.
• Validation using a curated benchmark of high- and medium-resolution cryo-EM structures.
• Comparison of ChemEM's scoring function against AutoDock Vina, with and without cryo-EM density information.

Main Results:

• ChemEM accurately placed ligands in protein-binding sites across a benchmark dataset.
• ChemEM's performance often surpassed existing cryo-EM PDB-deposited solutions.
• The ChemEM scoring function showed superior performance compared to AutoDock Vina, even without cryo-EM density input.

Conclusions:

• ChemEM enables precise ligand docking from cryo-EM data, significantly advancing structure-based drug discovery.
• Valuable insights for drug discovery can be obtained from medium-resolution cryo-EM maps.
• ChemEM highlights the increasing importance of cryo-EM structures in the pharmaceutical pipeline.