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In Vitro Analysis of E3 Ubiquitin Ligase Function
06:06

In Vitro Analysis of E3 Ubiquitin Ligase Function

Published on: May 14, 2021

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Mulan E3 ubiquitin ligase interacts with multiple E2 conjugating enzymes and participates in mitophagy by recruiting

Camilla T Ambivero1, Lucia Cilenti1, Stacey Main1

  • 1Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 12722 Research Parkway, Orlando, FL 32826, USA.

Cellular Signalling
|September 17, 2014
PubMed

Insights

Mulan, an E3 ubiquitin ligase, interacts with four E2 enzymes, including Ube2E3. This interaction facilitates mitophagy regulation through GABARAP binding, clarifying Mulan

Area of Science:

  • Mitochondrial biology
  • Ubiquitin-proteasome system
  • Autophagy and mitophagy

Background:

  • Mulan is an outer mitochondrial membrane E3 ubiquitin ligase involved in cell growth, death, and mitophagy.
  • Its precise mechanism of action and substrate specificity remain largely uncharacterized.
  • The unique topology of Mulan suggests a role in signaling between mitochondria and the cytoplasm.

Purpose of the Study:

  • To identify specific E2 ubiquitin conjugating enzymes that interact with Mulan.
  • To elucidate the molecular mechanism underlying Mulan's function in mitophagy.
  • To explore potential novel substrates and pathways regulated by Mulan.

Main Methods:

  • Modified yeast two-hybrid screens were employed to identify Mulan-E2 enzyme interactions.
  • Specific Mulan E2 complexes were generated by fusing E2 conjugating enzymes to Mulan's RING finger domain.
  • Interaction studies were performed to validate the binding of identified interactors.

Main Results:

  • Four E2 conjugating enzymes (Ube2E2, Ube2E3, Ube2G2, Ube2L3) were identified as specific Mulan interactors.
  • A novel interaction between Mulan-Ube2E3 and GABARAP (a member of the Atg8 family) was discovered.
  • This interaction requires Mulan's LC3-interacting region (LIR) and the presence of Ube2E3.

Conclusions:

  • Mulan functions through specific E2 enzyme interactions, suggesting its involvement in multiple cellular pathways.
  • The interaction with GABARAP provides a mechanistic link for Mulan's role in mitophagy.
  • Mulan acts as a key regulator in mitophagy, bridging mitochondrial status to the autophagic machinery.
Keywords:
E2 ubiquitin conjugating enzymesGABARAPMitochondriaMitophagyMulan E3 ubiquitin ligaseYeast two-hybrid system

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