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Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale
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Structural insights into CED-3 activation

Yini Li1, Lu Tian2, Ying Zhang2

  • 1Beijing Frontier Research Center for Biological Structures, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China liyini@mail.tsinghua.edu.cn.

Life Science Alliance
|July 4, 2023
PubMed

Insights

Programmed cell death in C. elegans involves CED-3 activation, requiring the CED-4 apoptosome. New cryo-EM structures reveal how CED-4 organization and CARD-CARD interactions regulate CED-3 activation, clarifying this cell death mechanism.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Programmed cell death (PCC) initiation in C. elegans is mediated by CED-3 activation, which depends on the CED-4 apoptosome.
  • The precise mechanism by which CED-4 facilitates CED-3 activation has remained largely unknown despite extensive research.

Purpose of the Study:

  • To elucidate the structural mechanisms underlying CED-4-mediated CED-3 activation in C. elegans.
  • To investigate the role of CED-4 oligomerization and CARD-CARD interactions in regulating programmed cell death.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) to determine structures of the CED-4 apoptosome and CED-4/CED-3 complexes.
  • Biochemical analyses to support structural findings and investigate protein interactions.

Main Results:

  • Cryo-EM revealed multiple oligomeric states for CED-4, both alone and in complex with CED-3, beyond the previously known octamer.
  • Structures captured distinct stages of CED-3 activation, highlighting the role of CARD-CARD interactions in promoting CED-3 activation.
  • Biochemical data confirmed that CARD-CARD interactions are crucial for CED-3 activation.

Conclusions:

  • The dynamic organization of the CED-4 apoptosome is a key regulatory point for initiating programmed cell death.
  • Conserved CARD-CARD interactions are essential for CED-3 activation, providing a molecular basis for programmed cell death initiation.

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