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Molecular mechanism of the interaction between MDM2 and p53

Oliver Schon1, Assaf Friedler, Mark Bycroft

  • 1Chemical Laboratory and Cambridge Centre for Protein Engineering, Cambridge University, MRC Centre, UK.

Journal of Molecular Biology
|October 17, 2002
PubMed

Insights

The p53-MDM2 interaction is crucial for cell cycle regulation. T18 phosphorylation on p53 peptides abrogates binding to MDM2, while other modifications have minimal effects, revealing key insights into this vital protein complex.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Structural Biology

Background:

  • The p53-MDM2 interaction is a critical regulator of the p53 tumor suppressor protein.
  • Dysregulation of this interaction is implicated in various cancers.
  • Understanding the molecular basis of this interaction is essential for therapeutic development.

Purpose of the Study:

  • To investigate the kinetic and thermodynamic factors governing the p53-MDM2 interaction.
  • To determine the impact of specific p53 post-translational modifications on binding affinity.
  • To elucidate the structural consequences of p53 peptide binding on MDM2.

Main Methods:

  • Peptide synthesis based on p53 residues 15-29.
  • Biochemical binding assays to determine dissociation constants (Kd).
  • Nuclear Magnetic Resonance (NMR) spectroscopy to study structural changes in MDM2.

Main Results:

  • Wild-type p53 peptide bound MDM2 with a Kd of 580 nM.
  • Phosphorylation at T18 significantly weakened p53-MDM2 binding (tenfold), abrogating the interaction.
  • Truncation studies revealed that residues 17-26 are critical for high-affinity binding.
  • NMR studies showed global conformational changes in MDM2 upon peptide binding, extending beyond the active site.

Conclusions:

  • Phosphorylation at threonine 18 (T18) is the primary modification responsible for disrupting the p53-MDM2 interaction.
  • Specific peptide sequences and structural elements within p53 are crucial for high-affinity MDM2 binding.
  • Ligand binding induces significant allosteric conformational changes in MDM2, impacting its overall domain dynamics.

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