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Quinolinate synthetase, an iron–sulfur enzyme in NAD biosynthesis
Author(s) -
Ollagnier-de Choudens Sandrine,
Loiseau Laurent,
Sanakis Yiannis,
Barras Frédéric,
Fontecave Marc
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.05.065
Subject(s) - nad+ kinase , quinolinate , biochemistry , dihydroxyacetone phosphate , cofactor , enzyme , chemistry , nicotinamide adenine dinucleotide , iron–sulfur cluster , nicotinamide adenine dinucleotide phosphate , biosynthesis , oxidase test , amino acid , quinolinic acid , tryptophan
Nicotinamide adenine dinucleotide (NAD) plays a crucial role as a cofactor in numerous essential redox biological reactions. NAD derives from quinolinic acid which is synthesized in Escherichia coli from l ‐aspartate and dihydroxyacetone phosphate (DHAP) as the result of the concerted action of two enzymes, l ‐aspartate oxidase (NadB) and quinolinate synthetase (NadA). We report here the characterization of NadA protein from E. coli . When anaerobically purified, the isolated soluble protein contains 3–3.5 iron and 3–3.5 sulfide/polypeptide chain. Mössbauer spectra of the 57 Fe‐protein revealed that the majority of the iron is in the form of a (4Fe–4S) 2+ cluster. An enzymatic assay for quinolinate synthetase activity was set up and allowed to demonstrate that the cluster is absolutely required for NadA activity. Exposure to air leads to degradation of the cluster and inactivate enzyme.