Structural highlights
Function[ILVC_CORGL] 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.[HAMAP-Rule:MF_00435] Publication Abstract from PubMedl-Valine belongs to the branched-chain amino acids (BCAAs) and is an essential amino acid that is crucial for all living organisms. l-Valine is industrially produced by the nonpathogenic bacterium Corynebacterium glutamicum and is synthesized by the BCAA biosynthetic pathway. Ketol-acid reductoisomerase (KARI) is the second enzyme in the BCAA pathway and catalyzes the conversion of (S)-2-acetolactate into (R)-2,3-dihydroxy-isovalerate, or the conversion of (S)-2-aceto-2-hydroxybutyrate into (R)-2,3-dihydroxy-3-methylvalerate. To elucidate the enzymatic properties of KARI from C. glutamicum (CgKARI), we successfully produced CgKARI protein and determined its crystal structure in complex with NADP(+) and two Mg(2+) ions. Based on the complex structure, docking simulations, and site-directed mutagenesis experiments, we revealed that CgKARI belongs to Class I KARI and identified key residues involved in stabilization of the substrate, metal ions, and cofactor. Furthermore, we confirmed the difference in the binding of metal ions that depended on the conformational change. Crystal Structure and Biochemical Characterization of Ketol-Acid Reductoisomerase from Corynebacterium glutamicum.,Lee D, Hong J, Kim KJ J Agric Food Chem. 2019 Jul 25. doi: 10.1021/acs.jafc.9b03262. PMID:31298526[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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This page was last modified 05:51, 7 August 2019.