PDBsum entry 4quh

Hydrolase/hydrolase inhibitor

PDB id: 4quh

Contents

Protein chains

233 a.a.

Ligands

GLY-VAL-ASP-ASP-ASP

ACE-ASP-GLU-VAL-ASP-0QE ×2

MRD ×2

AZI ×4

DTT

Waters ×421

PDB id:

4quh

Name:

Hydrolase/hydrolase inhibitor

Title:

Caspase-3 t140g

Structure:

Caspase-3. Chain: a, c. Synonym: casp-3, apopain, cysteine protease cpp32, cpp-32, protein yama, srebp cleavage activity 1, sca-1, caspase-3 subunit p17, caspase-3 subunit p12. Engineered: yes. Mutation: yes. Short peptde. Chain: d.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: casp3, cpp32. Expressed in: escherichia coli. Expression_system_taxid: 562. Synthetic: yes. Synthetic: yes

Resolution:

1.76Å R-factor: 0.155 R-free: 0.187

Authors:

C.Cade,P.D.Swartz,S.H.Mackenzie,A.C.Clark

Key ref:

C.Cade et al. (2014). Modifying caspase-3 activity by altering allosteric networks. Biochemistry, 53, 7582-7595. PubMed id: 25343534 DOI: 10.1021/bi500874k

Date:

10-Jul-14 Release date: 05-Nov-14

Protein chains

P42574  (CASP3_HUMAN) -  Caspase-3 from Homo sapiens

Seq: 277 a.a.

Struc: 233 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.3.4.22.56 - caspase-3.

DOI no: 10.1021/bi500874k

Biochemistry 53:7582-7595 (2014)

PubMed id: 25343534

Modifying caspase-3 activity by altering allosteric networks.

C.Cade, P.Swartz, S.H.MacKenzie, A.C.Clark.

ABSTRACT

Caspases have several allosteric sites that bind small molecules or peptides. Allosteric regulators are known to affect caspase enzyme activity, in general, by facilitating large conformational changes that convert the active enzyme to a zymogen-like form in which the substrate-binding pocket is disordered. Mutations in presumed allosteric networks also decrease activity, although large structural changes are not observed. Mutation of the central V266 to histidine in the dimer interface of caspase-3 inactivates the enzyme by introducing steric clashes that may ultimately affect positioning of a helix on the protein surface. The helix is thought to connect several residues in the active site to the allosteric dimer interface. In contrast to the effects of small molecule allosteric regulators, the substrate-binding pocket is intact in the mutant, yet the enzyme is inactive. We have examined the putative allosteric network, in particular the role of helix 3, by mutating several residues in the network. We relieved steric clashes in the context of caspase-3(V266H), and we show that activity is restored, particularly when the restorative mutation is close to H266. We also mimicked the V266H mutant by introducing steric clashes elsewhere in the allosteric network, generating several mutants with reduced activity. Overall, the data show that the caspase-3 native ensemble includes the canonical active state as well as an inactive conformation characterized by an intact substrate-binding pocket, but with an altered helix 3. The enzyme activity reflects the relative population of each species in the native ensemble.