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Literature summary 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

EC Number Protein Variants Comment Organism
1.1.1.3 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
1.1.1.3 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
2.7.2.4 I441A site-directed mutagenesis Arabidopsis thaliana
2.7.2.4 I552A site-directed mutagenesis Arabidopsis thaliana
2.7.2.4 Q443A site-directed mutagenesis Arabidopsis thaliana
2.7.2.4 Q524A site-directed mutagenesis Arabidopsis thaliana

Inhibitors

EC Number Inhibitors Comment Organism Structure
1.1.1.3 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
2.7.2.4 L-threonine
-
 Arabidopsis thaliana

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.7.2.4 5.5
-
 ATP
-
 Arabidopsis thaliana
2.7.2.4 11.6
-
 L-aspartate
-
 Arabidopsis thaliana

Metals/Ions

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

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
1.1.1.3 320000
-
 wild-type enzyme in presence of L-threonine, gel filtration Arabidopsis thaliana
1.1.1.3 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
2.7.2.4 470000
-
 gel filtration Arabidopsis thaliana

Organism

EC Number Organism UniProt Comment Textmining
1.1.1.3 Arabidopsis thaliana
-
 bifunctional enzyme showing aspartate dehydrogenase and aspartate kinase activity
-
2.7.2.4 Arabidopsis thaliana
-
-
-

Purification (Commentary)

EC Number Purification (Comment) Organism
2.7.2.4
-
 Arabidopsis thaliana

Reaction

EC Number Reaction Comment Organism Reaction ID
1.1.1.3 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
a

Substrates and Products (Substrate)

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

Subunits

EC Number Subunits Comment Organism
1.1.1.3 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

EC Number Synonyms Comment Organism
1.1.1.3 AK-HSDH
-
 Arabidopsis thaliana
1.1.1.3 aspartate kinase-homoserine dehydrogenase
-
 Arabidopsis thaliana
2.7.2.4 aspartokinase-homoserine dehydrogenase
-
 Arabidopsis thaliana

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
1.1.1.3 37
-
 assay at Arabidopsis thaliana

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
1.1.1.3 8
-
 assay at Arabidopsis thaliana