Determinants of substrate specificity in D-3-phosphoglycerate dehydrogenase. Conversion of the M. tuberculosis enzyme from one that does not use α-ketoglutarate as a substrate to one that does.
Arch Biochem Biophys
; 671: 218-224, 2019 08 15.
Article
em En
| MEDLINE
| ID: mdl-31344342
ABSTRACT
d-3-Phosphoglycerate dehydrogenase (PGDH) converts d-3-phosphoglycerate (PGA) to phosphohydroxypyruvate (PHP) in the first step of l-serine biosynthesis. This reaction is reversible, and some PGDHs are capable of using α-ketoglutarate (αKG) instead of PHP in the reverse direction to produce α-hydroxyglutarate. The enzymes so far shown to have this ability are Type II PGDHs, suggesting that this may be a common feature of the Type II enzymes. Type I PGDHs examined so far do not share this feature. Inspection of PGDH sequences shows that a GCFCI
WXKX motif is commonly found in Type II PGDHs while a GRAGT
WXRX motif is commonly associated with Type I PGDHs. The removal of the cationic side chain at the first position shown above in the Type I PGDH from Mycobacterium tuberculosis converts it to an enzyme capable of using αKG where the native enzyme is not. It also produces an enzyme that regenerates NAD+ in the forward reaction when coupled to phosphoserine aminotransferase, as was previously shown for E. coli PGDH. Substitution of an arginyl residue for a lysyl residue at the second position of ecPGDH, decreases the kcat/Km of the enzyme by approximately 50-fold when using αKG, but only approximately 3-fold when using PHP. This suggests that a PGDH dependent cycle that conserves NAD+ in E. coli may be operative in many other organisms expressing the GCFCI
WXKX motif.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Fosfoglicerato Desidrogenase
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Ácidos Cetoglutáricos
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Mycobacterium tuberculosis
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article