Interaction between p53 N terminus and core domain regulates specific and nonspecific DNA binding

Area of Science:

• Molecular Biology
• Cancer Biology
• Biochemistry

Background:

• p53 is a tumor suppressor protein regulating cell survival and proliferation.
• Its DNA binding and degradation are dynamically controlled for tumor suppression.
• The p53 N-terminus (NT) contains regulatory domains and phosphorylation sites.

Purpose of the Study:

• To investigate how the p53 N-terminus (NT) regulates DNA binding.
• To identify the specific regions within the NT that inhibit DNA binding.
• To understand the mechanism of NT-mediated regulation of p53 DNA binding affinity and specificity.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy to study protein-DNA interactions.
• In vitro and in vivo DNA binding assays.
• Analysis of p53 N-terminus (NT) interactions with the DNA binding domain (DBD).

Main Results:

• The p53 N-terminus (NT), specifically TAD2 and the proline-rich region (PRR), directly inhibits DNA binding by interacting with the DNA binding domain (DBD).
• NMR revealed these interactions occur at or near the DNA binding surface, potentially acting as a nucleic acid mimetic.
• The NT reduces overall DNA binding affinity but enhances specificity for target sequences.
• MDMX protein influences p53 binding to specific promoters versus nonspecific chromatin.

Conclusions:

• The p53 N-terminus (NT) plays a crucial role in modulating the affinity and specificity of p53's DNA binding.
• Interactions between the NT and the DNA binding domain (DBD) are key to this regulation.
• Posttranslational modifications and interacting proteins may fine-tune p53 DNA binding by altering the NT-DBD interaction.