The NAD-linked aromatic alpha-hydroxy acid dehydrogenase from Trypanosoma cruzi. A new member of the cytosolic malate dehydrogenases group without malate dehydrogenase activity.
Eur J Biochem
; 266(3): 903-10, 1999 Dec.
Article
em En
| MEDLINE
| ID: mdl-10583384
Trypanosoma cruzi, the protozoan parasite causing Chagas disease, contains a novel aromatic alpha-hydroxy acid dehydrogenase. This enzyme is responsible, together with tyrosine aminotransferase, for the catabolism of aromatic amino acids, which leads to the excretion of aromatic lactate derivatives into the culture medium. The gene encoding the aromatic alpha-hydroxy acid dehydrogenase has been cloned through a combined approach using screening of an expression genomic library with antibodies, peptide sequencing and PCR amplification. Its sequence shows high similarity to the cytosolic malate dehydrogenases. However, the enzyme has no malate dehydrogenase activity. The gene seems to be present in a single copy per haploid genome and is differentially expressed throughout the parasite's life cycle, the highest levels being found in the insect forms of T. cruzi. The purified recombinant enzyme, expressed in Escherichia coli, was unable to reduce oxaloacetate and had kinetic constants similar to those of the natural aromatic alpha-hydroxy acid dehydrogenase. Sequence comparisons suggest that the aromatic alpha-hydroxy acid dehydrogenase derives from a cytosolic malate dehydrogenase no longer present in the parasite, made redundant by the presence of a glycosomal malate dehydrogenase as a member of a shuttle device involving the mitochondrial isoenzyme.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Trypanosoma cruzi
/
Proteínas de Protozoários
/
Oxirredutases do Álcool
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Eur J Biochem
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Reino Unido