LIS - Legume Information System
Information about legume traits for crop improvement
GlycineMine
v5.1.0.3
Glycine data from LIS
v5.1.0.3
Glycine data from LIS
| Type | Domain |
| Description | Ketol-acid reductoisomerase (KARI; ( )), also known as acetohydroxy acid isomeroreductase (AHIR or AHAIR), catalyzes the conversion ofacetohydroxy acids into dihydroxy valerates in the second step of thebiosynthetic pathway for the essential branched-chain amino acids valine, leucine, and isoleucine. KARI catalyzes an unusual two-step reactionconsisting of an alkyl migration in which the substrate, either 2-acetolactate (AL) or 2-aceto-2-hydroxybutarate (AHB), is converted to 3-hydoxy-3-methyl-2-oxobutyrate or 3-hydoxy-3-methyl-2-pentatonate, followed by a NADPH-dependent reduction to give 2,3-dihydroxy-3-isovalerate or 2,3-dihydroxy-3-methylvalerate respectively [ , , , , , ].KARI is present only in bacteria, fungi, and plants, but not in animals. KARIs are divided into two classes on the basis of sequence length andoligomerization state. Class I KARIs are ~340 amino acid residues in length and include all fungal KARIs, whereas class II KARIs are ~490 residues longand include all plant KARIs. Bacterial KARIs can be either class I or class II. KARIs are composed of two types of domains, an N-terminal Rossmann folddomain and one or two C-terminal knotted domains. Two intertwinned knotted domains are required for function, and in the short-chain or class I KARIs,each polypeptide chain has one knotted domain. As a result, dimerization of two monomers forms two complete KARI active sites. In the long-chain or classII KARIs, a duplication of the knotted domain has occurred and, as a result, the protein does not require dimerization to complete its active site[ , , , , , ].The α-helical KARI C-terminal knotted domain can be described as a six- helix core in which helices coil like cable threads around each other, thusforming a bundle [ , , , , ]. |
| Short Name | KARI_C |
