Evidence for allosteric effects on p53 oligomerization induced by phosphorylation

Area of Science:

• Biochemistry
• Molecular Biology
• Protein Dynamics

Background:

• The tumor suppressor protein p53 is crucial for cellular regulation.
• p53 possesses a flexible, intrinsically disordered structure that enables dynamic interactions and rapid functional switching.
• The protein exists as a tetramer and can adopt various conformational states influenced by modifications.

Purpose of the Study:

• To investigate whether C-terminal phosphorylation of p53 stabilizes a specific conformation in the absence of DNA.
• To apply the allostery model to understand p53 conformational regulation.

Main Methods:

• Utilized monoclonal antibodies to indirectly measure p53 conformations (unfolded, folded, tetrameric).
• Employed a double antibody capture enzyme-linked immunosorbent assay (ELISA) to assess conformational changes.
• Phosphorylated human p53 in vitro using casein kinase 2.

Main Results:

• Phosphorylation by casein kinase 2 led to oligomerization and stabilization of the p53 wild-type conformation.
• Observed differential exposure of conformational epitopes (PAb1620, PAb240, DO12).
• Data indicated a decrease in the unfolded conformation and an increase in the folded conformation, correlating with increased oligomerization.

Conclusions:

• Activating enzymes can stabilize the oligomeric conformation of p53.
• The allostery model is a useful tool for understanding the regulation of intrinsically disordered proteins like p53.