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Literature summary for 1.1.1.3 extracted from

  • Paris, S.; Viemon, C.; Curien, G.; Dumas, R.
    Mechanism of control of Arabidopsis thaliana aspartate kinase-homoserine dehydrogenase by threonine (2003), J. Biol. Chem., 278, 5361-5366.
    View publication on PubMed

Protein Variants

Protein Variants Comment Organism
Q443A site-directed mutagenesis, altered reaction kinetics for both activities and altered inhibition pattern by L-threonine compared to the wild-type enzyme, asparate kinase activity is completely insensitive to inhibition by L-threonine, overview Arabidopsis thaliana
Q524A site-directed mutagenesis, altered reaction kinetics for both activities and altered inhibition pattern by L-threonine compared to the wild-type enzyme, overview Arabidopsis thaliana

Inhibitors

Inhibitors Comment Organism Structure
L-threonine the regulatory domain of the enzyme contains 2 binding sites, interaction with Gln443 leads to inhibition of the aspartate kinase activity and facilitates the binding of a second threonine on Gln524 leading to inhibition of the homoserine dehydrogenase activity, inhibition of the forward reactions Arabidopsis thaliana

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ required for aspartate kinase activity Arabidopsis thaliana

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
320000
-
wild-type enzyme in presence of L-threonine, gel filtration Arabidopsis thaliana
470000
-
wild-type enzyme in absence of L-threonine, mutant enzymes Q443A and Q524A both in presence or absence of L-threonine, gel filtration Arabidopsis thaliana

Organism

Organism UniProt Comment Textmining
Arabidopsis thaliana
-
bifunctional enzyme showing aspartate dehydrogenase and aspartate kinase activity
-

Reaction

Reaction Comment Organism Reaction ID
L-homoserine + NAD(P)+ = L-aspartate 4-semialdehyde + NAD(P)H + H+ bifunctional enzyme showing aspartate kinase, EC 2.7.2.4, and homoserine dehydrogenase activities Arabidopsis thaliana

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
L-homoserine + NADP+
-
Arabidopsis thaliana L-aspartate 4-semialdehyde + NADPH
-
r

Subunits

Subunits Comment Organism
More primary and secondary structure comparison, the bifunctional enzyme contains 2 homologous subdomains defined by a common loop-alpha helix-loop-beta strand-loop-beta strand motif, the enzymes' regulatory domain is composed of 2 subdomains, amino acid residues 414-453 and 495-534 Arabidopsis thaliana

Synonyms

Synonyms Comment Organism
AK-HSDH
-
Arabidopsis thaliana
aspartate kinase-homoserine dehydrogenase
-
Arabidopsis thaliana

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
37
-
assay at Arabidopsis thaliana

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8
-
assay at Arabidopsis thaliana