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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.

Authors :
Burgos ES
Ho MC
Almo SC
Schramm VL
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.

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