Identification of catalytic residues of a very large NAD-glutamate dehydrogenase from Janthinobacterium lividum by site-directed mutagenesis.
Biosci Biotechnol Biochem
; 78(12): 2045-50, 2014.
Article
em En
| MEDLINE
| ID: mdl-25126984
ABSTRACT
We previously found a very large NAD-dependent glutamate dehydrogenase with approximately 170 kDa subunit from Janthinobacterium lividum (Jl-GDH) and predicted that GDH reaction occurred in the central domain of the subunit. To gain further insights into the role of the central domain, several single point mutations were introduced. The enzyme activity was completely lost in all single mutants of R784A, K810A, K820A, D885A, and S1142A. Because, in sequence alignment analysis, these residues corresponded to the residues responsible for glutamate binding in well-known small GDH with approximately 50 kDa subunit, very large GDH and well-known small GDH may share the same catalytic mechanism. In addition, we demonstrated that C1141, one of the three cysteine residues in the central domain, was responsible for the inhibition of enzyme activity by HgCl2, and HgCl2 functioned as an activating compound for a C1141T mutant. At low concentrations, moreover, HgCl2 was found to function as an activating compound for a wild-type Jl-GDH. This suggests that the mechanism for the activation is entirely different from that for the inhibition.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Ácido Glutâmico
/
Subunidades Proteicas
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Burkholderiaceae
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Glutamato Desidrogenase
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Mutação
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Revista:
Biosci Biotechnol Biochem
Assunto da revista:
BIOQUIMICA
/
BIOTECNOLOGIA
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Japão