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

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. 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. 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.