1isg
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Crystal Structure Analysis of BST-1/CD157 with ATPgammaS
OverviewOverview
cADPR is the novel second messenger that elicits calcium release from, intracellular calcium stores and works independently of IP(3). In mammals, the ADP-ribosyl cyclase function is found in two membrane proteins, CD38, and BST-1/CD157. These enzymes, exposed extracellularly, bear cADPR, hydrolase and NAD glycohydrolase activities. In spite of its functional, importance, the structural basis of these enzymatic reactions remains, elusive. We determined the crystal structures of the extracellular region, of human BST-1 at atomic resolution in the free form and in complexes with, five substrate analogues: nicotinamide, NMN, ATPgammaS, ethenoNADP, and, ethenoNAD. The three-dimensional structural views of the reaction centre, with these ligands revealed the mode of substrate binding and the, catalytic mechanism of the multifunctional enzymatic reactions. In each, catalytic cleft of the dimeric enzyme, substrates are recognized, predominantly through van der Waals interactions with two tryptophan, residues, and thereby the N-glycosidic bond of NAD is correctly exposed, near a catalytic glutamate residue. Its carboxyl side-chain stabilizes the, catalytic intermediate of the S(N)-1 type reaction. This conformation of, the catalytic cleft also implies the mechanism of cyclization between the, adenine base and the ribose. The three key residues are invariant among, the sequences of BST-1, CD38, and Aplysia cyclase, and hence this, substrate recognition mode and catalytic scheme appear to be common in the, cyclase family.
About this StructureAbout this Structure
1ISG is a Single protein structure of sequence from Homo sapiens with SAP as ligand. Active as NAD(+) nucleosidase, with EC number 3.2.2.5 Full crystallographic information is available from OCA.
ReferenceReference
Crystallographic studies on human BST-1/CD157 with ADP-ribosyl cyclase and NAD glycohydrolase activities., Yamamoto-Katayama S, Ariyoshi M, Ishihara K, Hirano T, Jingami H, Morikawa K, J Mol Biol. 2002 Feb 22;316(3):711-23. PMID:11866528
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