Article

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

Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 04/2009; 106(12):4665-70. DOI: 10.1073/pnas.0900947106
Source: PubMed

ABSTRACT 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 A 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.

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Available from: Guozhang Zou, Aug 25, 2015
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    • "We also examined the activities of several PMI-based p53- Mdm2 and p53-Mdm4 antagonists, as these are high-affinity Mdm2-binding peptides obtained through screening phage display libraries (Pazgier et al., 2009; Table S3; Supplemental Experimental Procedures). The lysate BiLC assay showed that all were highly potent p53-Mdm2 and p53-Mdm4 antagonists (Figure S6F). "
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    • "Herein, we have made the first approach with ultra-small AuNPs (2 nm) conjugated with therapeutic peptide, PMI and neuropilin-1(Nrp-1) receptor-targeted peptide (Table 1) for cancer treatment. PMI also widely known as p12, is the most known potent inhibitor binding to MDM2 and MDMX complexes resulting in regulated activity and stability of tumor suppressive protein, p53 [15]. p53 is the known protein that transcriptionally regulates the expression of various target gene in response to cellular stress, which indirectly results in the cell cycle arrest, DNA damage or apoptosis [16]. "
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    • "In fact, many drug candidates, such as peptides [20] [21], peptidomimetics [22] [23], and small molecular inhibitors [24] [25] [26] [27], are designed to mimic the side chains of Phe19, Trp23, and Leu26. A detailed delineation of peptide-and peptidomimetic-based inhibitors on the basis of sequence of the p53 domain to modulate the p53–MDM2 and p53–MDMX interactions has been reported elsewhere [20] [28] [29]. Compared with the peptide-and peptidomimetic-based inhibitors, non-peptide small molecular inhibitors have advantages in terms of water solubility, desirable oral bioavailability, and cell permeability. "
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