Atomic-resolution protein structure determination by cryo-EM.

Area of Science:

• Structural Biology
• Biophysics
• Biochemistry

Background:

• Single-particle cryo-electron microscopy (cryo-EM) is a key technique for determining biological macromolecule structures.
• Current cryo-EM resolutions (better than 1.5 Å) are insufficient for direct visualization of atomic positions, hindering mechanistic and drug-binding studies.
• Advancements in hardware, software, and computational power have driven cryo-EM's expansion.

Purpose of the Study:

• To report a new cryo-EM method achieving unprecedented resolution for biological structures.
• To demonstrate the capability of visualizing atomic details, including hydrogen atoms and single-atom modifications.
• To enhance the quality of cryo-EM density maps for applications like structure-based drug design.

Main Methods:

• Utilized a newly developed transmission electron microscope for single-particle cryo-EM.
• Processed data to achieve a 1.25 Å resolution reconstruction of apoferritin.
• Compared the 3D information content with existing cryo-EM records.

Main Results:

• Achieved a 1.25 Å resolution structure of apoferritin, surpassing the previous world record.
• The resulting density map provides nearly double the 3D information content of the prior record.
• Demonstrated visualization of individual atoms, hydrogen atom density, and single-atom chemical modifications.

Conclusions:

• The new cryo-EM approach provides atomic-level detail previously unattainable.
• This high-resolution capability is crucial for understanding protein reaction mechanisms and drug interactions.
• Improved cryo-EM density map quality significantly benefits structure-based drug design.