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Structure of E6AP in complex with HPV16-E6 and p53 reveals a novel ordered domain important for E3 ligase activation

  • 0Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
Structure +

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January 16, 2025

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January 16, 2025

View abstract on PubMed

Summary

This summary is machine-generated.

High-risk human papillomavirus E6 targets the p53 tumor suppressor. Cryo-EM reveals how E6AP ligase interacts with E6 and p53, detailing E6AP’s N-terminal domain role in ubiquitin transfer and E6 protection.

Area Of Science

  • Biochemistry
  • Molecular Biology
  • Structural Biology

Background

  • High-risk human papillomavirus (HPV) E6 oncoprotein targets the cellular p53 tumor suppressor protein for degradation.
  • Understanding the E6AP ubiquitin ligase mechanism, including substrate positioning and E6 protection, is incomplete.

Purpose Of The Study

  • To elucidate the structural basis of the E6AP/E6/p53 complex formation and E6AP ligase activation.
  • To understand how E6AP mediates p53 ubiquitination and protects E6 from self-ubiquitination.

Main Methods

  • Determined the cryo-electron microscopy (cryo-EM) structure of the E6AP/E6/p53 complex.
  • Utilized in vivo modeling to analyze the tri-molecular complex interactions.
  • Identified key structural interactions governing E6AP ligase activity.

Main Results

  • The cryo-EM structure revealed the precise arrangement of E6AP, E6, and p53.
  • A terminal alpha helix in E6AP's N-terminal ordered domain (NOD) interacts with the HECT domain.
  • This NOD helix is crucial for E6AP ligase function, enhancing E6-E6AP binding, modulating p53 recognition, and protecting E6 from ubiquitination.

Conclusions

  • The N-terminal ordered domain of E6AP plays a critical regulatory role in the E6AP/E6/p53 complex.
  • Structural insights explain E6AP's mechanism in targeting p53 for degradation while protecting HPV E6.
  • This work provides a foundation for understanding viral oncoprotein interactions and developing targeted therapies.

Keywords:

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