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Human p53 phosphorylation mimic, S392E, increases nonspecific DNA affinity and thermal stability
Nicole Magnasco Nichols1, Kathleen Shive Matthews
1Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA.
Biochemistry
|January 5, 2002
Summary
The S392E mutant p53 protein shows increased stability and altered DNA binding compared to wild-type p53. These changes in the tumor suppressor protein may explain its "activated" phenotype in vivo.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- The tumor suppressor protein p53 is vital for cellular protection.
- DNA binding is essential for p53's function.
- The S392E mutant mimics p53 phosphorylation, suggesting activation.
Purpose of the Study:
- To investigate structural and functional differences between wild-type p53 and the S392E mutant.
- To understand how the S392E mutation affects p53's DNA binding properties.
- To elucidate the basis of the S392E mutant's "activated" phenotype.
Main Methods:
- Circular dichroism to assess thermal stability.
- Conformational antibody Ab1620 reactivity assays.
- DNA binding assays with varying DNA sequences (consensus and nonspecific).
Main Results:
- S392E mutant p53 exhibits enhanced thermal stability compared to wild-type.
- Structural alterations in the core DNA binding domain of S392E were observed.
- S392E showed increased affinity for nonspecific DNA but not consensus DNA without additives.
- Wild-type p53 binding affinity decreased with longer DNA sequences, unlike S392E.
Conclusions:
- The S392E mutation confers increased stability and altered DNA binding characteristics to p53.
- These modifications in the tumor suppressor protein likely contribute to its "activated" in vivo behavior.
- Findings provide insights into the functional regulation of p53 through post-translational modifications.