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A phosphoenzyme mimic, overlapping catalytic sites and reaction coordinate motion for human NAMPT.
A phosphoenzyme mimic, overlapping catalytic sites and reaction coordinate motion for human NAMPT.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2009 Aug 18; Vol. 106 (33), pp. 13748-53. Date of Electronic Publication: 2009 Aug 04. - Publication Year :
- 2009
-
Abstract
- Nicotinamide phosphoribosyltransferase (NAMPT) is highly evolved to capture nicotinamide (NAM) and replenish the nicotinamide adenine dinucleotide (NAD(+)) pool during ADP-ribosylation and transferase reactions. ATP-phosphorylation of an active-site histidine causes catalytic activation, increasing NAM affinity by 160,000. Crystal structures of NAMPT with catalytic site ligands identify the phosphorylation site, establish its role in catalysis, demonstrate unique overlapping ATP and phosphoribosyltransferase sites, and establish reaction coordinate motion. NAMPT structures with beryllium fluoride indicate a covalent H247-BeF(3)(-) as the phosphohistidine mimic. Activation of NAMPT by H247-phosphorylation causes stabilization of the enzyme-phosphoribosylpyrophosphate complex, permitting efficient capture of NAM. Reactant and product structures establish reaction coordinate motion for NAMPT to be migration of the ribosyl anomeric carbon from the pyrophosphate leaving group to the nicotinamide-N1 while the 5-phosphoryl group, the pyrophosphate moiety, and the nicotinamide ring remain fixed in the catalytic site.
- Subjects :
- Adenosine Triphosphatases chemistry
Adenosine Triphosphate chemistry
Binding Sites
Catalysis
Catalytic Domain
Crystallography, X-Ray methods
Diphosphates chemistry
Enzyme Activation
Histidine chemistry
Humans
Kinetics
Motion
Niacinamide chemistry
Phosphorylation
Substrate Specificity
Nicotinamide Phosphoribosyltransferase chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1091-6490
- Volume :
- 106
- Issue :
- 33
- Database :
- MEDLINE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 19666527
- Full Text :
- https://doi.org/10.1073/pnas.0903898106