Abstract
During apoptosis, hundreds of proteins are cleaved by caspases, most of them by the executioner caspase-3. However, caspase-7, which shares the same substrate primary sequence preference as caspase-3, is better at cleaving poly(ADP ribose) polymerase 1 (PARP) and Hsp90 cochaperone p23, despite a lower intrinsic activity. Here, we identified key lysine residues (K(38)KKK) within the N-terminal domain of caspase-7 as critical elements for the efficient proteolysis of these two substrates. Caspase-7's N-terminal domain binds PARP and improves its cleavage by a chimeric caspase-3 by ∼30-fold. Cellular expression of caspase-7 lacking the critical lysine residues resulted in less-efficient PARP and p23 cleavage compared with cells expressing the wild-type peptidase. We further showed, using a series of caspase chimeras, the positioning of p23 on the enzyme providing us with a mechanistic insight into the binding of the exosite. In summary, we have uncovered a role for the N-terminal domain (NTD) and the N-terminal peptide of caspase-7 in promoting key substrate proteolysis.
| Original language | English |
|---|---|
| Pages (from-to) | 5669-74 |
| Number of pages | 6 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 109 |
| Issue number | 15 |
| DOIs | |
| Publication status | Published - 10 Apr 2012 |
Keywords
- Amino Acid Motifs
- Amino Acid Sequence
- Apoptosis
- Caspase 3/metabolism
- Caspase 7/chemistry
- Cell Line
- Humans
- Intramolecular Oxidoreductases/metabolism
- Models, Molecular
- Molecular Sequence Data
- Poly(ADP-ribose) Polymerases/metabolism
- Prostaglandin-E Synthases
- Protein Structure, Tertiary
- Proteolysis
- Structure-Activity Relationship
- Substrate Specificity