Autoactivation of procaspase-9 by Apaf-1-mediated oligomerization

Mol Cell. 1998 Jun;1(7):949-57. doi: 10.1016/s1097-2765(00)80095-7.

Abstract

Activation of procaspase-9 by Apaf-1 in the cytochrome c/dATP-dependent pathway requires proteolytic cleavage to generate the mature caspase molecule. To elucidate the mechanism of activation of procaspase-9 by Apaf-1, we designed an in vitro Apaf-1-procaspase-9 activation system using recombinant components. Here, we show that deletion of the Apaf-1 WD-40 repeats makes Apaf-1 constitutively active and capable of processing procaspase-9 independent of cytochrome c an dATP. Apaf-1-mediated processing of procaspase-9 occurs at Asp-315 by an intrinsic autocatalytic activity of procaspase-9 itself. We provide evidence that Apaf-1 can form oligomers and may facilitate procaspase-9 autoactivation by oligomerizing its precursor molecules. Once activated, caspase-9 can initiate a caspase cascade involving the downstream executioners caspase-3, -6, and -7.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Apoptosis / genetics
  • Apoptosis / physiology
  • Apoptotic Protease-Activating Factor 1
  • Binding Sites
  • Biopolymers / chemistry
  • Biopolymers / metabolism
  • Caspase 3
  • Caspase 6
  • Caspase 7
  • Caspase 9
  • Caspases*
  • Catalysis
  • Cysteine Endopeptidases / chemistry
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism*
  • Cytochrome c Group / metabolism
  • Dimerization
  • Enzyme Activation
  • Enzyme Precursors / chemistry
  • Enzyme Precursors / genetics
  • Enzyme Precursors / metabolism*
  • Humans
  • Mutation / genetics
  • Protein Processing, Post-Translational
  • Proteins / chemistry
  • Proteins / genetics
  • Proteins / pharmacology*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Repetitive Sequences, Nucleic Acid / genetics
  • Tumor Cells, Cultured / cytology
  • Tumor Cells, Cultured / enzymology

Substances

  • APAF1 protein, human
  • Apoptotic Protease-Activating Factor 1
  • Biopolymers
  • Cytochrome c Group
  • Enzyme Precursors
  • Proteins
  • Recombinant Proteins
  • Adenosine Triphosphate
  • CASP3 protein, human
  • CASP6 protein, human
  • CASP7 protein, human
  • CASP9 protein, human
  • Caspase 3
  • Caspase 6
  • Caspase 7
  • Caspase 9
  • Caspases
  • Cysteine Endopeptidases