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.

Putative acetolactate synthase large subunit (ilvG); Function proposed based on presence of conserved amino acid motif, structural feature or limited homology; putative enzyme; Belongs to the TPP enzyme family.

poxB; Function of homologous gene experimentally demonstrated in an other organism; enzyme; Belongs to the TPP enzyme family.

3-isopropylmalate dehydrogenase; Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- methylpentanoate (3-isopropylmalate) to 3-carboxy-4-methyl-2- oxopentanoate. The product decarboxylates to 4-methyl-2 oxopentanoate.

Threonine deaminase; 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.

Tartrate dehydrogenase/decarboxylase (TDH) (D-malate dehydrogenase [decarboxylating]); Function of homologous gene experimentally demonstrated in an other organism; enzyme.

2-isopropylmalate synthase; Catalyzes the condensation of the acetyl group of acetyl-CoA with 3-methyl-2-oxobutanoate (2-oxoisovalerate) to form 3-carboxy-3- hydroxy-4-methylpentanoate (2-isopropylmalate); Belongs to the alpha-IPM synthase/homocitrate synthase family. LeuA type 1 subfamily.

Putative decarboxylase, Thiamine pyrophosphate-requiring; Function proposed based on presence of conserved amino acid motif, structural feature or limited homology; enzyme; Belongs to the TPP enzyme family.

Putative oxalyl-CoA decarboxylase (oxc, yfdU); Function proposed based on presence of conserved amino acid motif, structural feature or limited homology; putative enzyme; Belongs to the TPP enzyme family.