Reactivation of Mutant p53 through Interaction of a C-Terminal Peptide with the Core Domain

Abstract

A synthetic 22-mer peptide (peptide 46) derived from the p53 C-terminal domain can restore the growth suppressor function of mutant p53 proteins in human tumor cells (G. Selivanova et al., Nat. Med. 3:632–638, 1997). Here we demonstrate that peptide 46 binds mutant p53. Peptide 46 binding sites were found within both the core and C-terminal domains of p53. Lys residues within the peptide were critical for both p53 activation and core domain binding. The sequence-specific DNA binding of isolated tumor-derived mutant p53 core domains was restored by a C-terminal polypeptide. Our results indicate that C-terminal peptide binding to the core domain activates p53 through displacement of the negative regulatory C-terminal domain. Furthermore, stabilization of the core domain structure and/or establishment of novel DNA contacts may contribute to the reactivation of mutant p53. These findings should facilitate the design of p53-reactivating drugs for cancer therapy.

ACKNOWLEDGMENTS

We thank Bert Vogelstein, Johns Hopkins Oncology Center, for plasmids pC53-SN3 and PG-CAT; Moshe Oren, The Weizmann Institute, for the recombinant p53 expression baculovirus; Thierry Soussi, CNRS, Paris, France, for the p53 purification protocol; Karen Vousden, Frederick Cancer Research and Development Center, for the p53-I370/372/373 and p53-I381/382/286 mutant plasmids; and Michael Fritsche, Institute for Experimental Cancer Research, Freiburg, Germany, for the Saos-2-His-273 cells. We also thank Alexej Protopopov and Robert Skraban for help with preparation of the figures.

This work was supported by the Swedish Cancer Society, Åke Wibergs Stiftelse, and Concern Foundation for Cancer Research.