Characterization of the human gene encoding α-aminoadipate aminotransferase (AADAT)

In mammals, the conversion of alpha-aminoadipate to alpha-ketoadipate by alpha-aminoadipate aminotransferase (AADAT) is an intermediate step in lysine degradation. A gene encoding for alpha-aminoadipate aminotransferase and kynurenine aminotransferase activites had been previously identified in the rat (KAT/AadAT). We identified the human gene (AADAT) encoding for AADAT. It has a 2329bp cDNA, a 1278bp open-reading frame, and is predicted to encode 425 amino acids with a mitochondrial cleavage signal and a pyridoxal-phosphate binding site. AADAT is 73% and 72% identical to the mouse and rat orthologs, respectively. The genomic structure spans 30kb and consists of 13 exons. FISH studies localized the gene to 4q32.2. Two transcripts (similar to2.9 and similar to4.7 kb) were identified, with expression highest in liver. Bacterial expression studies confirm that the gene encodes for AADAT activity. The availability of the DNA sequence and enzyme assay will allow further evaluation of individuals suspected to have defects in this enzyme. (C) 2002 Elsevier Science (USA). All rights reserved.