1wd9
From Proteopedia
Calcium bound form of human peptidylarginine deiminase type4 (PAD4)
Overview
Peptidylarginine deiminase 4 (PAD4) is a Ca(2+)-dependent enzyme that catalyzes the conversion of protein arginine residues to citrulline. Its gene is a susceptibility locus for rheumatoid arthritis. Here we present the crystal structure of Ca(2+)-free wild-type PAD4, which shows that the polypeptide chain adopts an elongated fold in which the N-terminal domain forms two immunoglobulin-like subdomains, and the C-terminal domain forms an alpha/beta propeller structure. Five Ca(2+)-binding sites, none of which adopt an EF-hand motif, were identified in the structure of a Ca(2+)-bound inactive mutant with and without bound substrate. These structural data indicate that Ca(2+) binding induces conformational changes that generate the active site cleft. Our findings identify a novel mechanism for enzyme activation by Ca(2+) ions, and are important for understanding the mechanism of protein citrullination and for developing PAD-inhibiting drugs for the treatment of rheumatoid arthritis.
About this Structure
1WD9 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structural basis for Ca(2+)-induced activation of human PAD4., Arita K, Hashimoto H, Shimizu T, Nakashima K, Yamada M, Sato M, Nat Struct Mol Biol. 2004 Aug;11(8):777-83. Epub 2004 Jul 11. PMID:15247907 Page seeded by OCA on Sat May 3 13:29:53 2008
