PDBsum entry 4dcp

Hydrolase/hydrolase inhibitor

PDB id: 4dcp

Contents

Protein chains

141 a.a.

95 a.a.

Ligands

ACE-ASP-GLU-VAL-ASJ ×2

Waters ×369

PDB id:

4dcp

Name:

Hydrolase/hydrolase inhibitor

Title:

Crystal structure of caspase 3, l168f mutant

Structure:

Caspase-3 subunit p17. Chain: a, d. Engineered: yes. Mutation: yes. Caspase-3 subunit p12. Chain: b, e. Engineered: yes. Caspase inhibitor ac-devd-cho. Chain: c, f.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli. Expression_system_taxid: 562. Synthetic: yes

Resolution:

1.70Å R-factor: 0.199 R-free: 0.218

Authors:

S.J.Chung,H.J.Kang,S.J.Kim

Key ref:

H.J.Kang et al. (2012). Molecular insight into the role of the leucine residue on the L2 loop in the catalytic activity of caspases 3 and 7. Biosci Rep, 32, 305-313. PubMed id: 22304005

Date:

18-Jan-12 Release date: 12-Dec-12

Protein chains

P42574  (CASP3_HUMAN) -  Caspase-3 from Homo sapiens

Seq: 277 a.a.

Struc: 141 a.a.*

Protein chains

P42574  (CASP3_HUMAN) -  Caspase-3 from Homo sapiens

Seq: 277 a.a.

Struc: 95 a.a.

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: Chains A, B, D, E: E.C.3.4.22.56 - caspase-3.

Biosci Rep 32:305-313 (2012)

PubMed id: 22304005

Molecular insight into the role of the leucine residue on the L2 loop in the catalytic activity of caspases 3 and 7.

H.J.Kang, Y.M.Lee, M.S.Jeong, M.Kim, K.H.Bae, S.J.Kim, S.J.Chung.

ABSTRACT

Various apoptotic signals can activate caspases 3 and 7 by triggering the L2 loop cleavage of their proenzymes. These two enzymes have highly similar structures and functions, and serve as apoptotic executioners. The structures of caspase 7 and procaspase 7 differ significantly in the conformation of the loops constituting the active site, indicating that the enzyme undergoes a large structural change during activation. To define the role of the leucine residue on the L2 loop, which shows the largest movement during enzyme activation but has not yet been studied, Leu168 of caspase 3 and Leu191 of caspase 7 were mutated. Kinetic analysis indicated that the mutation of the leucine residues sometimes improved the Km but also greatly decreased the kcat, resulting in an overall decrease in enzyme activity. The tryptophan fluorescence change at excitation/emission = 280/350 nm upon L2-L2' loop cleavage was found to be higher in catalytically active mutants, including the corresponding wild-type caspase, than in the inactive mutants. The crystal structures of the caspase 3 mutants were solved and compared with that of wild-type. Significant alterations in the conformations of the L1 and L4 loops were found. These results indicate that the leucine residue on the L2 loop has an important role in maintaining the catalytic activity of caspases 3 and 7.