Structural visualization of the p53/RNA polymerase II assembly

Area of Science:

• Molecular Biology
• Structural Biology
• Cancer Research

Background:

• The tumor suppressor p53 is crucial for cellular stress response, activating transcription by recruiting transcription machinery.
• A direct interaction between p53 and RNA polymerase II (Pol II) has been observed but not fully characterized.

Purpose of the Study:

• To elucidate the structural basis of the human p53/Pol II interaction.
• To understand how p53 binding affects Pol II function and transcription regulation.

Main Methods:

• Single-particle cryo-electron microscopy (cryo-EM) was employed to determine the structure of the p53/Pol II complex.
• Structural docking and biochemical analyses were performed to validate the interaction and its functional consequences.

Main Results:

• p53 binds to the Rpb1 and Rpb2 subunits of Pol II, located within the DNA-binding cleft near the DNA entry site.
• The DNA-binding surface of p53 remains accessible in the complex, and the p53/Pol II cocomplex adopts a closed conformation.
• The interaction between p53 and Pol II significantly enhances Pol II elongation activity.

Conclusions:

• p53 structurally modulates Pol II's DNA-binding capabilities through its clamp domain.
• These findings provide critical insights into the mechanism of p53-mediated transcriptional regulation.