DIMERIZATION AND AUTOPROCESSING OF THE NEDD2 (CASPASE-2) PRECURSOR REQUIRES BOTH THE PRODOMAIN AND THE CARBOXYL-TERMINAL REGIONS

Nedd2 (caspase-2) is a cysteine protease of the caspase family that ha s been demonstrated to play a role in the apoptotic pathway. The 51-kD a precursor of Nedd2 undergoes cleavage into two subunits following va rious apoptotic stimuli. In this study, we have investigated the dimer ization of the Nedd2 precursor (pro-Nedd2) in Saccharomyces cerevisiae and its self-processing activity in vivo. We demonstrate that the exp ression of pro-Nedd2 in yeast cells results in processing of the precu rsor. A catalytically inactive pro-Nedd2 mutant dimerized in yeast, an d the dimerization required both the prodomain and the carboxyl-termin al residues. Aspartate mutants that block the removal of the p14/p12 s ubunits, but not the wild-type Nedd2, were shown to dimerize in yeast cells, suggesting that dimerization occurs prior to processing. In vit ro processing of pro-Nedd2 by recombinant active Nedd2 defined the asp artate residues that are crucial for processing to occur. Both the in vivo and in vitro processing of pro-Nedd2 directly correlated with its ability to induce cell death in transient overexpression experiments.