Structure and activation mechanism of the Drosophila initiator caspase Dronc

J Biol Chem. 2006 Mar 31;281(13):8667-74. doi: 10.1074/jbc.M513232200. Epub 2006 Jan 30.


Activation of an initiator caspase is essential to the execution of apoptosis. The molecular mechanisms by which initiator caspases are activated remain poorly understood. Here we demonstrate that the autocatalytic cleavage of Dronc, an important initiator caspase in Drosophila, results in a drastic enhancement of its catalytic activity in vitro. The autocleaved Dronc forms a homodimer, whereas the uncleaved Dronc zymogen exists exclusively as a monomer. Thus the autocatalytic cleavage in Dronc induces its stable dimerization, which presumably allows the two adjacent monomers to mutually stabilize their active sites, leading to activation. Crystal structure of a prodomain-deleted Dronc zymogen, determined at 2.5 A resolution, reveals an unproductive conformation at the active site, which is consistent with the observation that the zymogen remains catalytically inactive. This study revealed insights into mechanism of Dronc activation, and in conjunction with other observations, suggests diverse mechanisms for the activation of initiator caspases.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Caspases / chemistry*
  • Caspases / genetics
  • Caspases / metabolism
  • Caspases / physiology*
  • Catalysis
  • Chromatography, Gel
  • Conserved Sequence
  • Crystallography, X-Ray
  • Dimerization
  • Drosophila / enzymology*
  • Drosophila Proteins / chemistry*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism
  • Drosophila Proteins / physiology*
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme Activation
  • Enzyme Precursors / chemistry
  • Enzyme Precursors / genetics
  • Enzyme Precursors / metabolism
  • Immunohistochemistry
  • Kinetics
  • Models, Biological
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Secondary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Spectrum Analysis, Raman
  • Ultracentrifugation


  • Drosophila Proteins
  • Enzyme Precursors
  • Recombinant Proteins
  • Caspases
  • dronc protein, Drosophila

Associated data

  • PDB/2FP3