PMID: 16787777 , Related PDB ids: 2CJX, 2DKO

Authors:

Ganesan R, Mittl PR, Jelakovic S, Grutter MG

Title:

Extended substrate recognition in caspase-3 revealed by high resolution X-ray structure analysis.

Journal:

J Mol Biol. 2006 Jun 23;359(5):1378-88. Epub 2006 May 11.

Abstract:

Caspases are cysteine proteases involved in the signalling cascades of programmed cell death in which caspase-3 plays a central role, since it propagates death signals from intrinsic and extrinsic stimuli to downstream targets. The atomic resolution (1.06 Angstroms) crystal structure of the caspase-3 DEVD-cmk complex reveals the structural basis for substrate selectivity in the S4 pocket. A low-barrier hydrogen bond is observed between the side-chains of the P4 inhibitor aspartic acid and Asp179 of the N-terminal tail of the symmetry related p12 subunit. Site-directed mutagenesis of Asp179 confirmed the significance of this residue in substrate recognition. In the 1.06 Angstroms crystal structure, a radiation damage induced rearrangement of the inhibitor methylketone moiety was observed. The carbon atom that in a substrate would represent the scissile peptide bond carbonyl carbon clearly shows a tetrahedral coordination and resembles the postulated tetrahedral intermediate of the acylation reaction.