Phosphorylation represses Ets-1 DNA binding by reinforcing autoinhibition

Area of Science:

• Molecular Biology
• Cell Signaling
• Gene Expression Regulation

Background:

• Transcription factors control gene expression by binding DNA.
• Phosphorylation is a key post-translational modification linking cell signaling to gene regulation.

Purpose of the Study:

• To investigate the role of phosphorylation in regulating the DNA binding activity of the Ets-1 transcription factor.
• To elucidate the structural mechanism by which phosphorylation affects Ets-1 function.

Main Methods:

• Quantitative DNA-binding assays to measure Ets-1 binding affinity.
• Site-directed mutagenesis to identify key phosphorylation sites.
• Partial proteolysis to assess conformational changes.

Main Results:

• Calcium-dependent phosphorylation inhibits Ets-1 DNA binding by 50-fold.
• Four specific serine residues, distant from the DNA-binding domain, mediate this inhibition.
• An intact inhibitory module is essential for phosphorylation-dependent regulation.
• Phosphorylation stabilizes an inhibitory conformation of Ets-1.

Conclusions:

• Phosphorylation provides a structural mechanism to inhibit Ets-1 DNA binding via autoinhibition.
• Inhibitory modules can act as structural mediators for negative signaling events.
• This study reveals a novel regulatory function for phosphorylation in transcription factor activity.