Identification of ADP-ribosylation site in human glutamate dehydrogenase isozymes.
FEBS Lett
; 579(19): 4125-30, 2005 Aug 01.
Article
em En
| MEDLINE
| ID: mdl-16023112
ABSTRACT
When the influence of ADP-ribosylation on the activities of the purified human glutamate dehydrogenase isozymes (hGDH1 and hGDH2) was measured in the presence of 100 microM NAD+ for 60 min, hGDH isozymes were inhibited by up to 75%. If incubations were performed for longer time periods up to 3 h, the inhibition of hGDH isozymes did not increased further. This phenomenon may be related to the reversibility of ADP-ribosylation in mitochondria. ADP-ribosylated hDGH isozymes were reactivated by Mg2+-dependent mitochondrial ADP-ribosylcysteine hydrolase. The stoichiometry between incorporated ADP-ribose and GDH subunits shows a modification of one subunit per catalytically active homohexamer. Since ADP and GTP had no effects on the extent of modification, it would appear that the ADP-ribosylation is unlikely to occur in allosteric sites. It has been proposed that Cys residue may be involved in the ADP-ribosylation of GDH, although identification of the reactive Cys residue has not been reported. To identify the reactive Cys residue involved in the ADP-ribosylation, we performed cassette mutagenesis at three different positions (Cys59, Cys119, and Cys274) using synthetic genes of hGDH isozymes. Among the Cys residues tested, only Cys119 mutants showed a significant reduction in the ADP-ribosylation. These results suggest a possibility that the Cys119 residue has an important role in the regulation of hGDH isozymes by ADP-ribosylation.
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Bases de dados:
MEDLINE
Assunto principal:
Adenosina Difosfato Ribose
/
Glutamato Desidrogenase
/
Isoenzimas
Tipo de estudo:
Diagnostic_studies
Limite:
Humans
Idioma:
En
Revista:
FEBS Lett
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Coréia do Sul