Purification and characterization of the alanine aminotransferase from the hyperthermophilic Archaeon Pyrococcus furiosus and its role in alanine production
Alanine aminotransferase (AlaAT) was purified from cell extracts of the hyperthermophilic archaeon Pyrococcus furiosus by multistep chromatography. The enzyme has an apparent molecular mass of 93.5 kDa, as estimated by gel filtration, and consists of two identical subunits of 46 kDa, as deduced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the gene sequence. The AlaAT displayed a broader substrate specificity than AlaATs from eukaryal sources and exhibited significant activity with alanine, glutamate, and aspartate with either 2-oxoglutarate or pyruvate as the amino acceptor. Optimal activity was found in the pH range of 6.5 to 7.8 and at a temperature of over 95°C. The N-terminal amino acid sequence of the purified AlaAT was determined and enabled the identification of the gene encoding AlaAT (aat) in the P. furiosus genome database. The gene was expressed in Escherichia coli, and the recombinant enzyme was purified. The pH and temperature dependence, molecular mass, and kinetic parameters of the recombinant were indistinguishable from those of the native enzyme from P. furiosus. The kcat/Km values for alanine and pyruvate formation were 41 and 33 s1 mM1, respectively, suggesting that the enzyme is not biased toward either the formation of pyruvate, or alanine. Northern analysis identified a single 1.2-kb transcript for the aat gene. In addition, both the aat and gdh (encoding the glutamate dehydrogenase) transcripts appear to be coregulated at the transcriptional level, because the expression of both genes was induced when the cells were grown on pyruvate. The coordinated control found for the aat and gdh genes is in good agreement with these enzymes acting in a concerted manner to form an electron sink in P. furiosus.
Main Authors: | Ward, D.E., Kengen, S.W.M., van der Oost, J., de Vos, W.M. |
---|---|
Format: | Article/Letter to editor biblioteca |
Language: | English |
Subjects: | Life Science, |
Online Access: | https://research.wur.nl/en/publications/purification-and-characterization-of-the-alanine-aminotransferase |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Similar Items
-
'Pyrococcus furiosus, 30 years on'
by: Kengen, Servé W.M. -
Biochemical adaptations of two sugar kinases from the hyperthermophilic archaeon Pyrococcus furiosus
by: Verhees, C.H., et al. -
Argonaute of the archaeon Pyrococcus furiosus is a DNA-guided nuclease that targets cognate DNA
by: Swarts, D.C., et al. -
Crystallization and quaternary structure analysis of an Lrp-like regulatory protein from the hyperthermophile Pyrococcus furiosus
by: Sedelnikova, S.E., et al. -
Molecular and Biochemical Characterization of a Distinct Type of Fructose-1,6- Bisphosphatase from Pyrococcus furiosus
by: Verhees, C.H., et al.