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Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation
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Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation

Published on: March 5, 2018

Structural and biochemical studies on procaspase-8: new insights on initiator caspase activation

Nadine Keller1, Jirí Mares, Oliver Zerbe

  • 1Institute of Biochemistry, University of Zurich, CH-8057 Zurich, Switzerland.

Structure (London, England : 1993)
|March 13, 2009
PubMed

Insights

This study reveals the structure of inactive procaspase-8, showing it requires dimerization for activation. This finding explains why initiator caspases need a platform for their function in apoptosis and inflammation.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Structural Biology

Background:

  • Caspases are cysteine proteases crucial for apoptosis and inflammation.
  • Caspase-8 initiates extrinsic apoptotic pathways but its inactive zymogen structure was unknown.
  • Dysfunctional caspases are implicated in various diseases.

Purpose of the Study:

  • To determine the solution structure of monomeric, unprocessed procaspase-8 catalytic domain.
  • To elucidate the structural basis for procaspase-8 activation and its requirement for dimerization.
  • To investigate the role of dimerization and processing in caspase-8 activity.

Main Methods:

  • Solution structure determination using biophysical techniques.
  • Analysis of monomeric unprocessed procaspase-8 catalytic domain.
  • Site-directed mutagenesis to create specific mutants for activity assays.

Main Results:

  • The solution structure of monomeric, unprocessed procaspase-8 catalytic domain was determined.
  • The linker position and flexibility of active site loops in the zymogen were revealed.
  • Monomeric uncleaved procaspase-8 and dimerization-incompetent mutants showed no activity.

Conclusions:

  • Procaspase-8 is inactive in its monomeric, uncleaved state.
  • Dimerization is essential for initiator caspase-8 activation.
  • The findings provide detailed experimental support for the necessity of a dimerization platform in caspase-8 activation.

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