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Mutations of the PC2 substrate binding pocket alter enzyme specificity.
Magdalena M Kacprzak1, Manuel E Than, Luiz Juliano
1Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
The Journal of Biological Chemistry
|July 9, 2005
Summary
Investigating proprotein convertase 2 (PC2) specificity, researchers mutated key residues. The study found that substrate charge significantly impacts PC2 activity, and the binding cleft
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Proprotein convertase 2 (PC2) is a key enzyme in protein processing.
- Understanding PC2 specificity is crucial for deciphering its biological roles.
- The catalytic domain of PC2 shares homology with other proprotein convertases like furin.
Purpose of the Study:
- To investigate the molecular determinants of proprotein convertase 2 (PC2) substrate specificity.
- To identify specific residues within the PC2 catalytic domain that influence substrate recognition.
- To compare PC2 specificity with that of related enzymes, PC1 and furin.
Main Methods:
- Site-directed mutagenesis was employed to alter conserved and specific residues in the PC2 catalytic domain.
- Mutated PC2 enzymes were tested against various proenkephalin-derived and peptide B-derived substrates.
- Substrate specificity was evaluated using positional scanning variants to probe binding pocket interactions.
Main Results:
- Mutations at residue Ser206 abolished PC2 activity, while increased substrate positive charge enhanced specificity.
- The RE281GR mutation, distant from the active site, significantly altered the PC2 specificity pattern.
- Distinct alterations in substrate preference were observed for D278E and N356S mutations.
Conclusions:
- PC2 substrate specificity is influenced by specific residues, particularly those affecting the S6 pocket.
- The overall structure of the substrate-binding cleft, rather than individual residues, primarily dictates PC2 substrate binding.
- Further research into PC2 structure-function relationships can elucidate its role in various biological pathways.