title: Structural basis for high-affinity peptide inhibition of p53 interactions with MDM2 and MDMX.
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.
authors.affiliation: Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA.
authors.forename: Marzena
authors.initials: M
authors.lastname: Pazgier
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.forename: Guozhang
authors.initials: G
authors.lastname: Zou
authors.forename: Weirong
authors.initials: W
authors.lastname: Yuan
authors.forename: Changqing
authors.initials: C
authors.lastname: Li
authors.forename: Chong
authors.initials: C
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Juahdi
authors.initials: J
authors.lastname: Monbo
authors.forename: Davide
authors.initials: D
authors.lastname: Zella
authors.forename: Sergey G
authors.initials: SG
authors.lastname: Tarasov
authors.forename: Wuyuan
authors.initials: W
authors.lastname: Lu
mesh_terms: D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D017433:Protein Structure, Secondary; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C482775:MDM4 protein, human; D009687:Nuclear Proteins; D009842:Oligopeptides; D019151:Peptide Library; D010455:Peptides; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; C549069:threonyl-seryl-phenylalanyl-alanyl-glutamyl-tyrosyl-tryptophyl-asparagyl-leucyl-leucyl-seryl-proline; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2