Bifunctional aspartate kinase/homoserine dehydrogenase I; Derived by automated computational analysis using gene prediction method: Protein Homology; In the C-terminal section; belongs to the homoserine dehydrogenase family.

PLP-dependent threonine dehydratase; Catalyzes the anaerobic formation of alpha-ketobutyrate and ammonia from threonine in a two-step reaction. The first step involved a dehydration of threonine and a production of enamine intermediates (aminocrotonate), which tautomerizes to its imine form (iminobutyrate). Both intermediates are unstable and short-lived. The second step is the nonenzymatic hydrolysis of the enamine/imine intermediates to form 2- ketobutyrate and free ammonia. In the low water environment of the cell, the second step is accelerated by RidA.

Bifunctional aspartate kinase/homoserine dehydrogenase II; Derived by automated computational analysis using gene prediction method: Protein Homology; In the C-terminal section; belongs to the homoserine dehydrogenase family.

Phosphoserine transaminase; Catalyzes the reversible conversion of 3- phosphohydroxypyruvate to phosphoserine and of 3-hydroxy-2-oxo-4- phosphonooxybutanoate to phosphohydroxythreonine; Belongs to the class-V pyridoxal-phosphate-dependent aminotransferase family. SerC subfamily.

Low-specificity L-threonine aldolase; Low- specificity; catalyzes the formation of acetaldehyde and glycine from L-threonine; acts on L-threonine, L-allo-threonine, L-threo-phenylserine, and L-erythro-phenylserine; Derived by automated computational analysis using gene prediction method: Protein Homology.

4-hydroxythreonine-4-phosphate dehydrogenase PdxA; Catalyzes the NAD(P)-dependent oxidation of 4-(phosphooxy)-L- threonine (HTP) into 2-amino-3-oxo-4-(phosphooxy)butyric acid which spontaneously decarboxylates to form 3-amino-2-oxopropyl phosphate (AHAP).

L-threonine 3-dehydrogenase; Catalyzes the NAD(+)-dependent oxidation of L-threonine to 2- amino-3-ketobutyrate; Belongs to the zinc-containing alcohol dehydrogenase family.

Ketol-acid reductoisomerase; Involved in the biosynthesis of branched-chain amino acids (BCAA). Catalyzes an alkyl-migration followed by a ketol-acid reduction of (S)-2-acetolactate (S2AL) to yield (R)-2,3-dihydroxy-isovalerate. In the isomerase reaction, S2AL is rearranged via a Mg-dependent methyl migration to produce 3-hydroxy-3-methyl-2-ketobutyrate (HMKB). In the reductase reaction, this 2-ketoacid undergoes a metal-dependent reduction by NADPH to yield (R)-2,3-dihydroxy-isovalerate.

Lysine-sensitive aspartokinase 3; Catalyzes the formation of 4-phospho-L-aspartate from L-aspartate and ATP; functions in amino acid biosynthesis; lysine sensitive; Derived by automated computational analysis using gene prediction method: Protein Homology; Belongs to the aspartokinase family.