Structural basis for high-affinity peptide inhibition of p53 interactions with MDM2 and MDMX

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 106; no. 12; pp. 4665 - 4670
• Main Authors: Pazgier, Marzena, Liu, Min, Zou, Guozhang, Yuan, Weirong, Li, Changqing, Li, Chong, Li, Jing, Monbo, Juahdi, Zella, Davide, Tarasov, Sergey G, Lu, Wuyuan
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 24-03-2009; National Acad Sciences
• Subjects: Amino Acid Sequence; Bacteriophages; Binding sites; Biochemistry; Biological Sciences; Cancer; Crystal structure; Humans; Hydrogen bonds; Libraries; Ligation; Medical treatment; Models, Molecular; Molecular Sequence Data; Nuclear Proteins - chemistry; Nuclear Proteins - metabolism; Oligopeptides - chemistry; Oligopeptides - metabolism; Oligopeptides - pharmacology; Peptide Library; Peptides; Peptides - chemistry; Peptides - metabolism; Peptides - pharmacology; Private mortgage insurance; Protein Binding - drug effects; Protein Structure, Secondary; Proteins; Proto-Oncogene Proteins - chemistry; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-mdm2 - chemistry; Proto-Oncogene Proteins c-mdm2 - metabolism; Structure-Activity Relationship; Transactivation; Tumor Suppressor Protein p53 - chemistry; Tumor Suppressor Protein p53 - metabolism; Tumors
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0900947106

The oncoproteins MDM2 and MDMX negatively regulate the activity and stability of the tumor suppressor protein p53--a cellular process initiated by MDM2 and/or MDMX binding to the N-terminal transactivation domain of p53. MDM2 and MDMX in many tumors confer p53 inactivation and tumor survival, and are important molecular targets for anticancer therapy. We screened a duodecimal peptide phage library against site-specifically biotinylated p53-binding domains of human MDM2 and MDMX chemically synthesized via native chemical ligation, and identified several peptide inhibitors of the p53-MDM2/MDMX interactions. The most potent inhibitor (TSFAEYWNLLSP), termed PMI, bound to MDM2 and MDMX at low nanomolar affinities--approximately 2 orders of magnitude stronger than the wild-type p53 peptide of the same length (ETFSDLWKLLPE). We solved the crystal structures of synthetic MDM2 and MDMX, both in complex with PMI, at 1.6 Å resolution. Comparative structural analysis identified an extensive, tightened intramolecular H-bonding network in bound PMI that contributed to its conformational stability, thus enhanced binding to the 2 oncogenic proteins. Importantly, the C-terminal residue Pro of PMI induced formation of a hydrophobic cleft in MDMX previously unseen in the structures of p53-bound MDM2 or MDMX. Our findings deciphered the structural basis for high-affinity peptide inhibition of p53 interactions with MDM2 and MDMX, shedding new light on structure-based rational design of different classes of p53 activators for potential therapeutic use.