1r16

Publication Abstract from PubMed

ADP-ribosyl cyclase catalyzes the elimination of nicotinamide from NAD and cyclization to cADPR, a known second messenger in cellular calcium signaling pathways. We have determined to 2.0 A resolution the structure of Aplysia cyclase with ribose-5-phosphate bound covalently at C3' and with the base exchange substrate (BES), pyridylcarbinol, bound to the active site. In addition, further refinement at 2.4 A resolution of the structure of nicotinamide-bound cyclase, which was previously reported, reveals that ribose-5-phosphate is also covalently bound in this structure, and a second nicotinamide site was identified. The structures of native and mutant Glu179Ala cyclase were also solved to 1.7 and 2.0 A respectively. It is proposed that the second nicotinamide site serves to promote cyclization by clearing the active site of the nicotinamide byproduct. Moreover, a ribosylation mechanism can be proposed in which the cyclization reaction proceeds through a covalently bound intermediate.

ADP-ribosyl cyclase; crystal structures reveal a covalent intermediate.,Love ML, Szebenyi DM, Kriksunov IA, Thiel DJ, Munshi C, Graeff R, Lee HC, Hao Q Structure. 2004 Mar;12(3):477-86. PMID:15016363^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.