Multisite Phosphorylation Regulates the Structure and Auto-Inhibitory Function of the Intrinsically Disordered...

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• Multisite phosphorylation is crucial for cellular processes like cell cycle control and is implicated in cancer.
• The tumor suppressor protein p53 is regulated by phosphorylation, particularly in its intrinsically disordered terminal domains.
• The precise mechanisms by which phosphorylation controls p53's autoinhibition and DNA binding remain unclear.

Purpose of the Study:

• To investigate how phosphorylation affects the structural properties of the intrinsically disordered p53 N-terminal domain (NTD).
• To elucidate the impact of phosphorylation on the interaction between the p53 NTD and its DNA-binding domain (DBD).
• To reveal the molecular mechanisms underlying p53 autoinhibition regulated by phosphorylation.

Main Methods:

• All-atom molecular dynamics simulations.
• Enhanced sampling techniques.
• Analysis of structural properties and residue interactions.

Main Results:

• Phosphorylation significantly alters the structural properties of p53-NTD, affecting local structures and long-range interactions.
• T55 phosphorylation promotes the insertion of key aromatic residues into the DNA-binding pocket of the DBD, stabilizing NTD-DBD interactions.
• S46 phosphorylation, while not inducing NTD binding alone, enhances the inhibitory effect of T55 phosphorylation by reducing NTD's conformational entropy.

Conclusions:

• Phosphorylation on p53-NTD is a key regulator of its structure and self-inhibitory function.
• The findings provide detailed molecular insights into how phosphorylation controls the activity of intrinsically disordered proteins like p53.
• This research deepens our understanding of the molecular basis of p53 function in cellular processes and disease.