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Enhancement of p53 sequence-specific binding by DNA supercoiling
Emil Palecek1, Václav Brázda, Eva Jagelská
1Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno 612 65, Czech Republic. palecek@ibp.cz
Oncogene
|February 3, 2004
Summary
DNA supercoiling significantly enhances sequence-specific binding (SSDB) of wild-type p53 protein. Cruciform structures and DNA bends within supercoiled DNA further boost p53 SSDB, highlighting supercoiling's role in p53 regulation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The p53 protein is a crucial tumor suppressor involved in DNA repair and apoptosis.
- Understanding the factors influencing p53's DNA sequence-specific binding (SSDB) is vital for comprehending its regulatory network.
Purpose of the Study:
- To investigate the impact of DNA negative supercoiling on the SSDB of human wild-type (wt) p53 protein.
- To identify structural DNA elements that enhance p53 SSDB.
Main Methods:
- A novel competition assay was developed to assess p53 SSDB.
- Supercoiled (sc) DNAs with varying p53 target sequences were used as competitors.
- Comparison of competitor strength between supercoiled, linearized, and relaxed DNAs, including those with cruciform structures.
Main Results:
- Supercoiled DNAs were superior competitors compared to linearized or relaxed forms.
- DNAs with extruded cruciforms within the target sequence exhibited the highest competitor strength.
- Full-length wt p53 SSDB was enhanced by supercoiling, unlike deletion mutants (p53CΔ30) or the core domain, indicating C-terminal involvement.
Conclusions:
- DNA supercoiling, DNA bends, and cruciform structures enhance p53 SSDB.
- DNA supercoiling is a key determinant in p53 sequence-specific binding.
- Supercoiling likely plays a significant role in the p53 regulatory network.