3ULK

E. coli Ketol-acid reductoisomerase in complex with NADPH and Mg2+

3ULK の概要

• エントリーDOI: 10.2210/pdb3ulk/pdb
• 関連するPDBエントリー: 1yrl 1yve 3FR7 3FR8
• 分子名称: Ketol-acid reductoisomerase, NADPH DIHYDRO-NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE, SULFATE ION, ... (5 entities in total)
• 機能のキーワード: branched-chain amino acid biosynthesis, rossmann fold, reductoisomerase, acetolactate, oxidoreductase
• 由来する生物種: Escherichia coli
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 110744.35

構造登録者

Wong, S.H.,Lonhienne, T.G.A.,Winzor, D.J.,Schenk, G.,Guddat, L.W. (登録日: 2011-11-11, 公開日: 2012-10-17, 最終更新日: 2023-11-01)

主引用文献

Wong, S.H.,Lonhienne, T.G.A.,Winzor, D.J.,Schenk, G.,Guddat, L.W.
Bacterial and plant ketol-acid reductoisomerases have different mechanisms of induced fit during the catalytic cycle
J.Mol.Biol., 424:168-179, 2012

PubMed Abstract: Ketol-acid reductoisomerase (KARI) is the second enzyme in the branched-chain amino acid biosynthesis pathway, which is found in plants, fungi and bacteria but not in animals. This difference in metabolism between animals and microorganisms makes KARI an attractive target for the development of antimicrobial agents. Herein we report the crystal structure of Escherichia coli KARI in complex with Mg(2+) and NADPH at 2.3Å resolution. Ultracentrifugation studies confirm that the enzyme exists as a tetramer in solution, and isothermal titration calorimetry shows that the binding of Mg(2+) increases structural disorder while the binding of NADPH increases the structural rigidity of the enzyme. Comparison of the structure of the E. coli KARI-Mg(2+)-NADPH complex with that of enzyme in the absence of cofactors shows that the binding of Mg(2+) and NADPH opens the interface between the N- and C-domains, thereby allowing access for the substrates to bind: the existence of only a small opening between the domains in the crystal structure of the unliganded enzyme signifies restricted access to the active site. This observation contrasts with that in the plant enzyme, where the N-domain can rotate freely with respect to the C-domain until the binding of Mg(2+) and/or NADPH stabilizes the relative positions of these domains. Support is thereby provided for the idea that plant and bacterial KARIs have evolved different mechanisms of induced fit to prepare the active site for catalysis.

PubMed: 23036858
DOI: 10.1016/j.jmb.2012.09.018

実験手法

X-RAY DIFFRACTION (2.3 Å)