Disordered Motifs and Domains in Cell Control - October 11-15, 2014

Disordered Motifs and Domains in Cell Control

Poster Session II

43-POS Board 19 NMR Study of the Interaction between MDM2 and a Peptide Selected by mRNA Display Takashi Nagata 1,2 , Kie Shirakawa 3 , Naohiro Kobayashi 4 , Hirokazu Shiheido 3 , Noriko Tabata 3 , Yuko Sakuma-Yonemura 3 , Kenichi Horisawa 3 , Masato Katahira 1,2 , Nobuhide Doi 3 , Hiroshi Yanagawa 3 . 1 Kyoto University, Uji, Japan, 3 Keio University, Yokohama, Japan, 2 Kyoto University, Uji, Japan, 4 Osaka University, Suita, Japan. OBJECTIVE: MDM2 is an oncoprotein who binds to the intrinsically disordered region (IDR) of tumor suppressor p53 and inhibits its functions. p53 prevents tumorigenesis through cell cycle arrest or apoptosis of cells in response to cellular stress such as DNA damage. Thus, inactivation of p53 by MDM2 leads to the development of several human cancers. Peptides that mimic the MDM2-binding region of p53-IDR reportedly restore the anti-cancer activity of the p53 pathway. We aimed to obtain the peptide that has a higher potency and affinity to MDM2 than the known ones and elucidate the mechanism of the strong binding. RESULTS: We screened for the MDM2-binding peptide from large random peptide libraries in two stages by means of mRNA display. The obtained 12-mer peptide, which we named MIP, exhibited higher affinity to MDM2 than the reported ones as confirmed by SPR. Experiments using living cells showed that MIP has superior binding activity and potency to prevent tumor cell growth. We have then determined the structure of MIP and MDM2 in the bound form by solution NMR method. CONCLUSIONS: Comparison between the structures of MIP:MDM2 complex and previously reported p53 peptide:MDM2, DI:MDM2, and PMI:MDM2 complexes showed that the stronger binding and higher anti-MDM2 activity observed for MIP can be explained as due to its enlarged binding surface over previously reported peptides. Additionally, MIP was found to have tendency to form some secondary structure in the hydrophobic solution environments. These findings provide fruitful hints for drug discovery against diseases caused by abrogation of the function of intrinsically disordered proteins.

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