Development of Peptidomimetics Targeting IAPs

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Inhibitor of apoptosis proteins (IAPs), like XIAP, prevent programmed cell death (apoptosis) by inhibiting caspases.
• The interaction between Smac (second mitochondria-derived activator of caspases) and the XIAP BIR3 domain is a critical target for inducing apoptosis.

Purpose of the Study:

• To characterize the peptide binding pocket of the XIAP BIR3 domain.
• To identify the minimum peptide sequence required to inhibit the Smac-BIR3 interaction.
• To establish the structure-activity relationship (SAR) for peptide-based Smac-IAP binding inhibitors.

Main Methods:

• Development of a Smac 7-mer displacement assay to measure binding to the XIAP BIR3 pocket.
• Physical and biochemical analysis of various peptides.
• Structural elucidation of the BIR3 peptide binding pocket.

Main Results:

• Determined the minimum peptide sequence essential for inhibiting Smac-BIR3 interaction.
• Detailed the dimensions and topology of the XIAP BIR3 peptide binding pocket.
• Established the SAR for peptide inhibitors targeting Smac-IAP binding.

Conclusions:

• Understanding the SAR of peptide inhibitors provides a foundation for designing novel therapeutics.
• Targeting the Smac-BIR3 interaction with specific peptides offers a promising strategy for cancer therapy by promoting apoptosis.