Late onset N-acetylglutamate synthase deficiency caused by hypomorphic alleles

Hum Mutat. 2005 Mar;25(3):293-8. doi: 10.1002/humu.20146.

Abstract

N-acetylglutamate (NAG) is a unique cofactor that is essential for the conversion of ammonia to urea in the liver. N-acetylglutamate synthase (NAGS) catalyzes the formation of NAG. Deficiency of NAGS causes a block in ureagenesis resulting in hyperammonemia. Although a number of mutations have been identified in the NAGS gene, their effects on NAGS enzymatic activity have not been examined. We describe here three mutations in two families with NAGS deficiency. Studies of the purified recombinant mutant proteins revealed deleterious effects on NAGS affinity for substrates, and on the rate of catalysis. These studies provide a better understanding of the function of NAGS, and the mechanisms for deleterious effect of mutations causing inherited NAGS deficiency.

Publication types

  • Case Reports
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Age of Onset
  • Alleles
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Amino-Acid N-Acetyltransferase / chemistry
  • Amino-Acid N-Acetyltransferase / deficiency*
  • Amino-Acid N-Acetyltransferase / genetics
  • Amino-Acid N-Acetyltransferase / physiology
  • Animals
  • Brain Death
  • Catalysis
  • Child
  • Consensus Sequence
  • DNA Mutational Analysis
  • Dietary Proteins / adverse effects
  • Dietary Proteins / pharmacokinetics
  • Fatal Outcome
  • Female
  • Glutamates / metabolism*
  • Glutamic Acid / metabolism
  • Humans
  • Hyperammonemia / enzymology
  • Hyperammonemia / epidemiology
  • Hyperammonemia / genetics*
  • Infant, Newborn
  • Learning Disabilities / genetics
  • Male
  • Molecular Sequence Data
  • Multiple Trauma / surgery
  • Mutagenesis, Site-Directed
  • Mutation, Missense
  • Point Mutation
  • Postoperative Complications
  • RNA Splice Sites / genetics
  • Recombinant Fusion Proteins / metabolism
  • Substrate Specificity
  • Urea / metabolism
  • Vertebrates / genetics

Substances

  • Dietary Proteins
  • Glutamates
  • RNA Splice Sites
  • Recombinant Fusion Proteins
  • Glutamic Acid
  • Urea
  • Amino-Acid N-Acetyltransferase
  • NAGS protein, human
  • N-acetylglutamic acid