Crystal Structure of Human CD47 in Complex with Engineered SIRPα.D1(N80A)

Area of Science:

• Structural Biology
• Immunology
• Protein Crystallography

Background:

• Targeting the CD47/SIRPα signaling pathway is a promising strategy for enhancing anti-tumor immunity.
• The detailed crystal structure of the CD47/SIRPα complex has remained largely uncharacterized.
• Understanding this interaction is crucial for developing novel immunotherapies.

Purpose of the Study:

• To analyze the structural interface of the complex formed between CD47 and IMM01, a novel SIRPα-Fc fusion protein.
• To elucidate the molecular interactions governing CD47/SIRPα binding.
• To provide a structural foundation for the rational design of CD47-targeting therapeutics.

Main Methods:

• Crystallization of the IMM01-Fab/CD47 complex.
• X-ray diffraction data collection and structure determination using molecular replacement (PHASER).
• Model building (COOT) and refinement (REFMAC) to analyze the protein-protein interface.

Main Results:

• The crystal structure revealed that IMM01 effectively buries the CD47 surface.
• Key hydrogen bonds and salt bridge interactions at the interface were identified and found to be highly conserved.
• Structural analysis showed similarities to previously reported CD47-SIRPα interactions, with minor variations in salt bridge formation due to conformational differences.

Conclusions:

• The study successfully determined the crystal structure of the IMM01/CD47 complex.
• This provides critical structural insights into the CD47/SIRPα binding interface.
• The findings offer a structural basis for advancing the clinical application of CD47-targeting agents for cancer immunotherapy.