BRCA1-derived peptide constructs exhibit sequence-dependent features compatible with modulation of the p53-MDM2 axis.

BACKGROUND: The p53-MDM2 interaction is a central regulator of p53 protein stability and an important target for restoration of p53 function. Most peptide-based approaches targeting this interaction are derived from the p53 transactivation domain and preserve the canonical F-W-L hydrophobic motif. Here, BRCA1-derived peptide constructs were used to investigate how hydrophobic motif composition and sequence context influence peptide compatibility with the MDM2 binding interface. METHODS AND RESULTS: Short peptide segments derived from BRCA1 phosphorylation regions were engineered to contain hydrophobic anchor residues corresponding to the p53-MDM2 interaction while permitting variation in motif composition, including non-canonical F-W-F configurations. Peptides were evaluated using molecular docking, molecular dynamics simulations, and cellular assays based on EGFP-linker-peptide fusion constructs in HEK293T cells. Several BRCA1-derived peptides were associated with increased p53 protein levels in this system, with pBR3 and pBR4 showing the highest mean levels. Notably, both peptides contained non-canonical F-W-F motifs and showed greater activity than several peptides with comparable docking scores. Molecular dynamics and residue-level contact occupancy analyses were consistent with sustained association of the peptides with the MDM2 binding cleft despite interaction patterns that differed from those of reference p53-derived inhibitors. CONCLUSIONS: These findings indicate that modulation of the p53-MDM2 axis is influenced by both hydrophobic motif composition and sequence context. The results further suggest that alternative hydrophobic residue arrangements can support compatibility with the MDM2 binding interface, providing a framework for exploring non-p53-derived peptide architectures targeting the p53-MDM2 interaction.