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Activation of p53 DNA binding activity by point mutation
N J Marston1, R L Ludwig, K H Vousden
1ABL Basic Research Program, NCI-FCRDC, Frederick, Maryland 21702, USA.
Oncogene
|July 22, 1998
Summary
Altering the C-terminus of the p53 tumor suppressor protein can lead to constitutive DNA binding activity. Specific mutations and deletions activate p53, retaining its cell cycle arrest and apoptosis functions.
Area of Science:
- Molecular Biology
- Protein Biochemistry
- Cancer Biology
Background:
- The p53 tumor suppressor protein regulates cellular responses.
- p53 activity is modulated by conformational changes affecting DNA binding.
- Allosteric regulation of p53 DNA binding involves its C-terminus.
Purpose of the Study:
- To investigate the role of the p53 C-terminus in regulating DNA binding.
- To identify specific regions and residues critical for p53 conformational control.
- To assess the functional consequences of constitutively active p53 mutants.
Main Methods:
- Site-directed mutagenesis of p53 C-terminal lysine residues.
- Deletion mutagenesis of the p53 C-terminus.
- In vitro DNA binding assays.
- Analysis of transcriptional activity, cell cycle arrest, and apoptosis.
Main Results:
- Deletion of the C-terminal 16 amino acids did not activate DNA binding.
- Further deletion of eight amino acids or mutation of three lysine residues resulted in constitutive p53 DNA binding.
- Constitutively active mutants showed reduced DNA binding site specificity.
- Mutants retained transcriptional activity and induced cell cycle arrest and apoptosis.
Conclusions:
- The p53 C-terminus plays a crucial role in regulating DNA binding activity.
- Specific lysine residues within the C-terminus are important for maintaining latent p53 conformation.
- Constitutive p53 activation via C-terminal modification can retain tumor suppressor functions.