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Yeast As a Chassis for Developing Functional Assays to Study Human P53
14:57

Yeast As a Chassis for Developing Functional Assays to Study Human P53

Published on: August 4, 2019

Acetylation of the DNA binding domain regulates transcription-independent apoptosis by p53

Stephen M Sykes1, Timothy J Stanek, Amanda Frank

  • 1Biomedical Graduate Studies, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

The Journal of Biological Chemistry
|June 5, 2009
PubMed

Insights

Acetylation of tumor suppressor p53 at lysine 120 is crucial for both nuclear and mitochondrial functions. This modification regulates transcription-independent apoptosis by influencing protein interactions at the mitochondria.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • The tumor suppressor p53 plays a critical role in apoptosis, acting both in the nucleus via transcription and directly at mitochondria.
  • While nuclear functions of p53 are well-studied, the regulation of its transcription-independent apoptotic roles remains unclear.
  • Acetylation of p53 at lysine 120 (Lys-120) is known to be important for apoptosis induction.

Purpose of the Study:

  • To investigate the role of p53 Lys-120 acetylation in its transcription-independent apoptotic functions.
  • To determine if Lys-120 acetylation affects p53 localization and interactions at the mitochondria.
  • To elucidate the mechanism by which Lys-120 acetylation regulates mitochondrial apoptosis.

Main Methods:

  • Immunofluorescence to detect mitochondrial localization of acetylated p53.
  • Co-immunoprecipitation assays to analyze protein-protein interactions (p53, BCL-XL, BAK, MCL-1).
  • Functional assays using site-directed mutagenesis (Lys-120 to alanine or glutamine) and apoptosis measurements.

Main Results:

  • The Lys-120-acetylated form of p53 is enriched at mitochondria.
  • Lys-120 acetylation does not affect p53 binding to BCL-XL or BAK directly.
  • Blocking Lys-120 acetylation impairs the displacement of MCL-1 from BAK, inhibiting apoptosis.
  • Mutation of Lys-120 to mimic cancer-associated non-acetylated forms inhibits transcription-independent apoptosis.
  • Enforced Lys-120 acetylation enhances transcription-independent apoptosis.

Conclusions:

  • Lys-120 acetylation of p53 is a critical regulatory event for its transcription-independent apoptotic functions.
  • This acetylation influences mitochondrial apoptosis by modulating the interaction between MCL-1 and BAK.
  • The findings reveal a dual role for Lys-120 acetylation in both transcription-dependent and -independent p53-mediated apoptosis.

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