P53 Latency: C-TERMINAL DOMAIN PREVENTS BINDING OF p53 CORE TO TARGET BUT NOT TO NONSPECIFIC DNA SEQUENCES

Tatiana Yakovleva,Aladdin Pramanik,Takashi Kawasaki,Koichi Tan-No,Irina Gileva,Heléne Lindegren,Ülo Langel,Tomas J Ekström,Rudolf Rigler,Lars Terenius,Georgy Bakalkin

doi:10.1074/jbc.m100482200

Abstract

The p53 transcription factor is either latent or activated through multi-site phosphorylation and acetylation of the negative regulatory region in its C-terminal domain (CTD). How CTD modifications activate p53 binding to target DNA sequences via its core domain is still unknown. It has been proposed that nonmodified CTD interacts either with the core domain or with DNA preventing binding of the core domain to DNA and that the fragments of the CTD regulatory region activate p53 by interfering with these interactions. We here characterized the sequence and target specificity of p53 activation by CTD fragments, interaction of activating peptides with p53 and target DNA, and interactions of "latent" p53 with DNA by a band shift assay and by fluorescence correlation spectroscopy. In addition to CTD fragments, several long basic peptides activated p53 and also transcription factor YY1. These peptides and CTD aggregated target DNA but apparently did not interact with p53. The potency to aggregate DNA correlated with the ability to activate p53, suggesting that p53 binds to target sequences upon interactions with tightly packed DNA in aggregates. Latent full-length p53 dissociated DNA aggregates via its core and CTD, and this effect was potentiated by GTP. Latent p53 also formed complexes via both its core and CTD with long nontarget DNA molecules. Such p53-DNA interactions may occur if latent p53 binding to DNA via CTD prevents the interaction of the core domain with target DNA sites but not with nonspecific DNA sequences.

Highlights

The p53 transcription factor is either latent or activated through multi-site phosphorylation and acetylation of the negative regulatory region in its C-terminal domain (CTD)
Latent p53 formed complexes via both its core and CTD with long nontarget DNA molecules. Such p53-DNA interactions may occur if latent p53 binding to DNA via CTD prevents the interaction of the core domain with target DNA sites but not with nonspecific DNA sequences
Activation of p53 Binding to Specific DNA Sequences by Basic Peptides—Sequence specificity of peptide effects on p53 binding to DNA was studied in a band shift assay

Summary

Introduction

The p53 transcription factor is either latent or activated through multi-site phosphorylation and acetylation of the negative regulatory region in its C-terminal domain (CTD). Our findings suggest that p53 is activated for binding to target DNA sites when it interacts with juxtaposed DNA molecules in DNA aggregates via both its core and CTD.

Results

Conclusion