ADP-ribosyl cyclase; crystal structures reveal a covalent intermediate.
Structure
; 12(3): 477-86, 2004 Mar.
Article
em En
| MEDLINE
| ID: mdl-15016363
ABSTRACT
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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
ADP-Ribosil Ciclase
Limite:
Animals
Idioma:
En
Revista:
Structure
Assunto da revista:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
/
BIOTECNOLOGIA
Ano de publicação:
2004
Tipo de documento:
Article