The human homologue of the yeast polyubiquitination factor Ufd2p is cleaved by caspase 6 and granzyme B during apoptosis.
In the present study, we demonstrate that a human homologue of Ufd2p (a yeast protein that catalyses the formation of long polyubiquitin chains, and is implicated in responses to environmental stress), UFD2 (ubiquitin fusion degradation protein-2), is cleaved during apoptosis induced by multiple stimuli, including UVB irradiation, Fas ligation, staurosporine ... treatment and cytotoxic lymphocyte granule-induced death. Caspase 6 and granzyme B efficiently cleave UFD2 [k(cat)/K(m)=(4-5) x 10(4) M(-1) x s(-1)] at Asp(123), whereas caspases 3 and 7 cleave UFD2 approx. 10-fold less efficiently immediately upstream at Asp(109). Thus UFD2 is added to the growing list of proteins with closely spaced caspase and granzyme B cleavage sites, suggesting the presence of a previously unrecognized, conserved motif. Both cleavage sites are contained and conserved within a novel 300-amino-acid N-terminal domain present in apparent UFD2 orthologues in mice and zebrafish, but absent in all UFD2 family members in lower eukaryotes. Full-length recombinant UFD2 exhibited ubiquitin-protein ligase ('E3')-like ubiquitination activity in vitro, but this activity was abolished in recombinant UFD2 truncated at the granzyme B/caspase 6 cleavage site. Cleavage of UFD2 by caspases or granzyme B within this putative regulatory N-terminal domain might have important functional consequences within the apoptotic cascade.
Mesh Terms:
Amino Acid Motifs, Amino Acid Sequence, Apoptosis, Baculoviridae, Binding Sites, Blotting, Northern, Caspase 6, Caspases, Cloning, Molecular, Enzyme Inhibitors, Fungal Proteins, Granzymes, Hela Cells, Humans, Kinetics, Molecular Sequence Data, Mutagenesis, Site-Directed, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Recombinant Proteins, Saccharomyces cerevisiae Proteins, Sequence Homology, Amino Acid, Serine Endopeptidases, Staurosporine, Tissue Distribution, Ubiquitin, Ubiquitin-Conjugating Enzymes, Ultraviolet Rays
Amino Acid Motifs, Amino Acid Sequence, Apoptosis, Baculoviridae, Binding Sites, Blotting, Northern, Caspase 6, Caspases, Cloning, Molecular, Enzyme Inhibitors, Fungal Proteins, Granzymes, Hela Cells, Humans, Kinetics, Molecular Sequence Data, Mutagenesis, Site-Directed, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Recombinant Proteins, Saccharomyces cerevisiae Proteins, Sequence Homology, Amino Acid, Serine Endopeptidases, Staurosporine, Tissue Distribution, Ubiquitin, Ubiquitin-Conjugating Enzymes, Ultraviolet Rays
Biochem. J.
Date: Feb. 01, 2002
PubMed ID: 11802788
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