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.

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.

Acetolactate synthase; Derived by automated computational analysis using gene prediction method: Protein Homology.

Acetolactate synthase catalytic subunit; Catalyzes the formation of 2-acetolactate from pyruvate; also known as acetolactate synthase large subunit; Derived by automated computational analysis using gene prediction method: Protein Homology.

Dihydroxy-acid dehydratase; Catalyzes the dehydration of 2,3-dihydroxy-3-methylbutanoate to 3-methyl-2-oxobutanoate in valine and isoleucine biosynthesis; Derived by automated computational analysis using gene prediction method: Protein Homology; Belongs to the IlvD/Edd family.

Converts isocitrate to alpha ketoglutarate; Derived by automated computational analysis using gene prediction method: Protein Homology.

Glutamate synthase; Derived by automated computational analysis using gene prediction method: Protein Homology.

hydroxymethylglutaryl-CoA lyase; Catalyzes the formation of acetoacetate and acetyl-CoA from 3-hydroxy-3-methylglutaryl-CoA; Derived by automated computational analysis using gene prediction method: Protein Homology.

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.