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Updated: Sep 7, 2026
Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
Published on: September 28, 2012
DNA damage-inducible phosphorylation of p53 at N-terminal sites including a novel site, Ser20, requires
1Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Abstract:
Upon DNA damage, p53 has been shown to be modified at a number of N-terminal phosphorylation sites including Ser15 and -33. Here we show that phosphorylation is induced as well at a novel site, Ser20. Phosphorylation at Ser15, -20 and -33 can occur within minutes of DNA damage. Interestingly, while the DNA-binding activities of p53 appear to be dispensable, efficient phosphorylation at these three sites requires the tetramerization domain of p53. Substitution of an artificial tetramerization domain for this region also permits phosphorylation at the N-terminus, suggesting that oligomerization is important for DNA damage-induced signalling to p53.
Insights
DNA damage triggers phosphorylation of the tumor suppressor p53 at novel Ser20 site, alongside existing Ser15 and Ser33 sites. This process requires p53
Area of Science:
- Molecular Biology
- Cellular Signaling
- Cancer Research
Background:
- The tumor suppressor protein p53 is a critical regulator of cellular responses to DNA damage.
- N-terminal phosphorylation sites, such as Ser15 and Ser33, are known modification sites in p53 following DNA damage.
- The precise mechanisms and kinetics of p53 phosphorylation in response to DNA damage are still under investigation.
Purpose of the Study:
- To identify and characterize novel phosphorylation sites on p53 induced by DNA damage.
- To investigate the kinetics of p53 phosphorylation at identified N-terminal sites.
- To determine the role of p53's structural domains, particularly the tetramerization domain, in DNA damage-induced phosphorylation.
Main Methods:
- Induction of DNA damage in cells.
- Analysis of p53 protein modifications using phospho-specific antibodies and mass spectrometry.
- Site-directed mutagenesis to substitute the tetramerization domain with an artificial domain.
Main Results:
- DNA damage induces rapid phosphorylation of p53 at a newly identified N-terminal site, Ser20, in addition to Ser15 and Ser33.
- Phosphorylation at Ser15, Ser20, and Ser33 occurs within minutes of DNA damage.
- Efficient phosphorylation at these N-terminal sites requires the p53 tetramerization domain, even when DNA-binding activity is dispensable.
Conclusions:
- A novel phosphorylation site, Ser20, is identified in p53 following DNA damage, contributing to the N-terminal modification pattern.
- Oligomerization mediated by the tetramerization domain is crucial for efficient DNA damage-induced signaling to p53 N-terminal phosphorylation.
- These findings highlight the importance of p53 oligomerization in its post-translational modification and cellular response to genotoxic stress.
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