Structural basis of procaspase-9 recruitment by the apoptotic protease-activating factor 1.
Caspase-9-mediated apoptosis (programmed cell death) plays a central role in the development and homeostasis of all multicellular organisms. Mature caspase-9 is derived from its procaspase precursor as a result of recruitment by the activating factor Apaf-1. The crystal structures of the caspase-recruitment domain of Apaf-1 by itself and in complex with the prodomain of procaspase-9 have been determined at 1.6 and 2.5 A resolution, respectively. These structures and other evidence reveal that each molecule of Apaf-1 interacts with a molecule of procaspase-9 through two highly charged and complementary surfaces formed by non-conserved residues; these surfaces determine recognition specificity through networks of intermolecular hydrogen bonds and van der Waals interactions. Mutation of the important interface residues in procaspase-9 or Apaf-1 prevents or reduces activation of procaspase-9 in a cell-free system. Wild-type, but not mutant, prodomains of caspase-9 completely inhibit catalytic processing of procaspase-9. Furthermore, analysis of homologues from Caenorhabditis elegans indicates that recruitment of CED-3 by CED-4 is probably mediated by the same set of conserved structural motifs, with a corresponding change in the specificity-determining residues.
Qin
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Department of Chemistry, Princeton University, New Jersey 08544, USA.
Srinivasula
S M
SM
Wu
G
G
Fernandes-Alnemri
T
T
Alnemri
E S
ES
Shi
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D053477:Apoptotic Protease-Activating Factor 1; D001665:Binding Sites; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics; D055672:Static Electricity
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D061945:Caspase Inhibitors; D004792:Enzyme Precursors; D011506:Proteins; D011993:Recombinant Fusion Proteins; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases