Disease relevance of N-acetylornithine

• We have identified in Xanthomonas campestris a novel N-acetylornithine transcarbamylase that replaces ornithine transcarbamylase in the canonic arginine biosynthetic pathway of several Eubacteria [1].
• Arginine auxotrophic phenotype of mutation in pyrA of Salmonella typhimurium: role of N-acetylornithine in the maturation of mutant carbamylphosphate synthetase [2].
• A cloned DNA fragment from Anabaena sp. strain PCC 7120 that complements an arginine auxotrophic mutant from the same organism was found to include an open reading frame encoding a 427-residue polypeptide that is homologous to N-acetylornithine aminotransferase from Bacillus subtilis, Escherichia coli, and Saccharomyces cerevisiae [3].

High impact information on N-acetylornithine

• The specificity for N-acetylornithine is conferred by hydrogen bonding with residues in the proline-rich loop via water molecules and by hydrophobic interactions with residues from the adjacent 80's, 120's, and proline-rich loops [1].
• Mechanistic analysis of the argE-encoded N-acetylornithine deacetylase [4].
• Solvent kinetic isotope effects on the hydrolysis of N-acetylornithine have been determined, and a linear proton inventory suggests that a single proton transfer occurs in a partially rate-limiting step [4].
• The gene encoding N-acetylornithine aminotransferase in bacteria has been named argD [3].
• The enzyme had a very narrow substrate specificity, and could only catalyze the transamination of alpha-ketoglutarate with ornithine or N-acetylornithine, and of glutamate-5-semialdehyde with glutamate and alanine [5].

Biological context of N-acetylornithine

• Moreover, this is the first example of the occurrence of an N-acetylornithine conjugate in the biotransformation of a xenobiotic in animals [6].

Associations of N-acetylornithine with other chemical compounds

• The enzyme catalyses the freely reversible interchange of an acetyl group between N-acetylornithine and glutamate and has a specific activity of 22 mumol.min-1.mg-1 at 37 degrees C and pH 7 [7].

Gene context of N-acetylornithine

• One is the ARG8 gene coding for N-acetylornithine aminotransferase [8].

Analytical, diagnostic and therapeutic context of N-acetylornithine

• Cloning, purification, crystallization and preliminary X-ray crystallographic analysis of the biosynthetic N-acetylornithine aminotransferases from Salmonella typhimurium and Escherichia coli [9].

References