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Death domain assembly mechanism revealed by crystal structure of the oligomeric PIDDosome core complex

Hyun Ho Park1, Emmanuelle Logette, Stefan Raunser

  • 1Weill Medical College, Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA.

Cell
|February 10, 2007
PubMed

Insights

Death domain (DD) proteins form signaling complexes. This study reveals the crystal structure of the PIDD DD-RAIDD DD complex, elucidating assembly mechanisms for caspase-2 activation.

Area of Science:

  • Structural biology
  • Molecular signaling

Background:

  • Death domain (DD) superfamily proteins mediate signaling complex assembly for caspase and kinase activation.
  • Mechanisms of these oligomeric complexes remain largely unknown.

Purpose of the Study:

  • To determine the crystal structure of the PIDD DD and RAIDD DD complex.
  • To elucidate the assembly mechanism of the PIDDosome, the core of the caspase-2 activating complex.

Main Methods:

  • X-ray crystallography to determine the structure of the PIDD DD and RAIDD DD complex.
  • Mutagenesis studies to investigate the role of identified interfaces in complex assembly and function.

Main Results:

  • The PIDD DD and RAIDD DD monomers assemble into a 7:5 complex (RAIDD:PIDD).
  • An asymmetric assembly mechanism results in quasi-equivalent environments for all DDs within the complex.
  • Eight unique asymmetric interfaces, classified into three types, mediate the assembly and cover most of the DD surface.
  • Mutagenesis of these interfaces disrupts assembly and impairs caspase-2 activation.

Conclusions:

  • The identified three types of interactions represent key modes for DD superfamily complex assembly.
  • Understanding these interactions provides insights into the mechanisms of caspase-2 activation and broader signaling complex formation.

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