The reported human NADsyn2 is ammonia-dependent NAD synthetase from a pseudomonad

J Biol Chem. 2003 Aug 29;278(35):33056-9. doi: 10.1074/jbc.M302276200. Epub 2003 May 30.


Nicotinamide-adenine dinucleotide (NAD+) synthetases catalyze the last step in NAD+ metabolism in the de novo, import, and salvage pathways that originate from tryptophan (or aspartic acid), nicotinic acid, and nicotinamide, respectively, and converge on nicotinic acid mononucleotide. NAD+ synthetase converts nicotinic acid adenine dinucleotide to NAD+ via an adenylylated intermediate. All of the known eukaryotic NAD+ synthetases are glutamine-dependent, hydrolyzing glutamine to glutamic acid to provide the attacking ammonia. In the prokaryotic world, some NAD+ synthetases are glutamine-dependent, whereas others can only use ammonia. Earlier, we noted a perfect correlation between presence of a domain related to nitrilase and glutamine dependence and then proved in the accompanying paper (Bieganowski, P., Pace, H. C., and Brenner, C. (2003) J. Biol. Chem. 278, 33049-33055) that the nitrilase-related domain is an essential, obligate intramolecular, thiol-dependent glutamine amidotransferase in the yeast NAD+ synthetase, Qns1. Independently, human NAD+ synthetase was cloned and shown to depend on Cys-175 for glutamine-dependent but not ammonia-dependent NAD+ synthetase activity. Additionally, it was claimed that a 275 amino acid open reading frame putatively amplified from human glioma cell line LN229 encodes a human ammonia-dependent NAD+ synthetase and this was speculated largely to mediate NAD+ synthesis in human muscle tissues. Here we establish that the so-called NADsyn2 is simply ammonia-dependent NAD+ synthetase from Pseudomonas, which is encoded on an operon with nicotinic acid phosphoribosyltransferase and, in some Pseudomonads, with nicotinamidase.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amide Synthases / chemistry*
  • Amide Synthases / genetics*
  • Ammonia / chemistry*
  • Base Sequence
  • Chromosomes, Human, Pair 22 / metabolism
  • Cloning, Molecular
  • CpG Islands
  • Cysteine / chemistry
  • DNA / metabolism
  • Gene Library
  • Glutamic Acid / chemistry
  • Glutamine / chemistry
  • Humans
  • Hydrolysis
  • Molecular Sequence Data
  • Muscles / metabolism
  • NAD / chemistry*
  • Nicotinamidase / metabolism
  • Open Reading Frames
  • Operon
  • Phylogeny
  • Protein Structure, Tertiary
  • Pseudomonas / metabolism*
  • Sequence Homology, Nucleic Acid


  • Glutamine
  • NAD
  • Glutamic Acid
  • Ammonia
  • DNA
  • Nicotinamidase
  • Amide Synthases
  • NAD+ synthase
  • Cysteine