Related Experiment Video

Updated: Sep 12, 2025

Visualization and Quantification of Endogenous Intra-Organelle Protein Interactions at ER-Mitochondria Contact Sites by Proximity Ligation Assays
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Visualization and Quantification of Endogenous Intra-Organelle Protein Interactions at ER-Mitochondria Contact Sites by Proximity Ligation Assays

Published on: October 20, 2023

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Crystal structure of Fis1 and Bap31 provides information on protein-protein interactions at mitochondria-associated

Minh Duc Nguyen1,2, Yonghyeok Kim1, Seung-Hyun Bae1,3

  • 1Research Institute, National Cancer Center, Goyang-si, Gyeonggi, Republic of Korea.

Communications Biology
|August 6, 2025
PubMed

Insights

Structural insights reveal how Fis1, a mitochondrial fission protein, interacts with Bap31 at ER-mitochondria contact sites. This clarifies the molecular basis of mitochondria-associated ER membranes (MAMs) function.

Area of Science:

  • Cell Biology
  • Structural Biology
  • Biochemistry

Background:

  • Mitochondria and endoplasmic reticulum (ER) interact at mitochondria-associated ER membranes (MAMs), crucial for cellular functions.
  • The mitochondrial protein Fis1 and ER protein Bap31 are known to interact at these sites.

Purpose of the Study:

  • To elucidate the structural basis of the Fis1-Bap31 interaction.
  • To understand the role of Fis1 conformations in regulating interactions at MAMs.

Main Methods:

  • X-ray crystallography was used to determine the structures of human Fis1.
  • A co-crystal structure of Fis1 bound to Bap31 was obtained.

Main Results:

  • Two distinct conformations of the cytosolic domain of human Fis1 were resolved.
  • The crystal structure revealed Bap31 binding to the tetratricopeptide repeat (TPR) domain of Fis1.
  • One Fis1 conformation suggests a potential autoinhibitory mechanism.

Conclusions:

  • The study provides detailed structural insights into the Fis1-Bap31 interaction at ER-mitochondria contact sites.
  • These findings contribute to understanding the molecular mechanisms governing MAMs.

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