3CIR

E. coli Quinol fumarate reductase FrdA T234A mutation

3CIR の概要

• エントリーDOI: 10.2210/pdb3cir/pdb
• 分子名称: Fumarate reductase flavoprotein subunit, Fumarate reductase iron-sulfur subunit, Fumarate reductase subunit C, ... (8 entities in total)
• 機能のキーワード: electron transport, tricarboxylic acid cycle, oxidoreductase
• 由来する生物種: Escherichia coli; 詳細
• 細胞内の位置: Cell inner membrane; Multi-pass membrane protein: P0A8Q0 P0A8Q3
• タンパク質・核酸の鎖数: 8
• 化学式量合計: 245351.71

構造登録者

Tomasiak, T.M.,Maklashina, E.,Cecchini, G.,Iverson, T.M. (登録日: 2008-03-11, 公開日: 2008-04-01, 最終更新日: 2023-08-30)

主引用文献

Tomasiak, T.M.,Maklashina, E.,Cecchini, G.,Iverson, T.M.
A threonine on the active site loop controls transition state formation in Escherichia coli respiratory complex II.
J.Biol.Chem., 283:15460-15468, 2008

PubMed Abstract: In Escherichia coli, the complex II superfamily members succinate:ubiquinone oxidoreductase (SQR) and quinol:fumarate reductase (QFR) participate in aerobic and anaerobic respiration, respectively. Complex II enzymes catalyze succinate and fumarate interconversion at the interface of two domains of the soluble flavoprotein subunit, the FAD binding domain and the capping domain. An 11-amino acid loop in the capping domain (Thr-A234 to Thr-A244 in quinol:fumarate reductase) begins at the interdomain hinge and covers the active site. Amino acids of this loop interact with both the substrate and a proton shuttle, potentially coordinating substrate binding and the proton shuttle protonation state. To assess the loop's role in catalysis, two threonine residues were mutated to alanine: QFR Thr-A244 (act-T; Thr-A254 in SQR), which hydrogen-bonds to the substrate at the active site, and QFR Thr-A234 (hinge-T; Thr-A244 in SQR), which is located at the hinge and hydrogen-bonds the proton shuttle. Both mutations impair catalysis and decrease substrate binding. The crystal structure of the hinge-T mutation reveals a reorientation between the FAD-binding and capping domains that accompanies proton shuttle alteration. Taken together, hydrogen bonding from act-T to substrate may coordinate with interdomain motions to twist the double bond of fumarate and introduce the strain important for attaining the transition state.

PubMed: 18385138
DOI: 10.1074/jbc.M801372200

実験手法

X-RAY DIFFRACTION (3.65 Å)