type	Journal Article
authors	Alberati-Giani, D.; Buchli, R.; Malherbe, P.; Broger, C.; Lang, G.; Kohler, C.; Lahm, H. W.; Cesura, A. M.
title	Isolation and expression of a cDNA clone encoding human kynureninase
journal	Eur J Biochem
Activity	3.7.1.3
ui	96314506
year	(1996)
volume	239
number	2
pages	460-8.
keywords	Amino Acid Sequence
abstract	Kynureninase (L-kynurenine hydrolase), a pyridoxal-5'-phosphate- (pyridoxal-P)-dependent enzyme, catalyses the cleavage of L-kynurenine and L-3-hydroxykynurenine into anthranilic and 3-hydroxyanthranilic acids, respectively. In this report, we describe the isolation of a cDNA clone encoding human kynureninase. Degenerate oligonucleotides designed from the amino acid sequences of peptides from rat liver kynureninase, were used as primers for reverse-transcription PCR of rat kidney RNA. The resulting rat cDNA product was then used to screen a human hepatoma cell line (Hep G2) cDNA library. Analysis of a positive cDNA clone showed the presence of an insert of 1651 nucleotides containing an open reading frame coding for a protein of 456 amino acids (theoretical molecular mass = 52357 Da). The predicted amino acid sequence of human kynureninase displayed high similarity to that reported for the rat enzyme and to a Saccharomyces cerevisiae gene product putatively ascribed to kynureninase. Profile analysis of kynureninase primary structure indicated the presence of a pyridoxal-P- binding site consensus sequence assigned to class-V aminotransferases, with Lys276 being the residue binding the cofactor. RNA blot analysis of human tissues, including brain, showed the presence of an approximately 2.0-kb mRNA species in all tissues tested. A second mRNA species (approximately 2.6 kb) was also detected in some tissues. After transfection of HEK-293 cells with the cDNA coding for kynureninase, the K(m) values of L-kynurenine and DL-3-hydroxykynurenine for the recombinant enzyme were 671 +/- 37 microM and 13.2 +/- 2.0 microM, respectively.
last changed	2002/11/12 16:17