2BGI

X-Ray Structure of the Ferredoxin-NADP(H) Reductase from Rhodobacter capsulatus complexed with three molecules of the detergent n-heptyl- beta-D-thioglucoside at 1.7 Angstroms

2BGI の概要

• エントリーDOI: 10.2210/pdb2bgi/pdb
• 関連するPDBエントリー: 2BGJ
• 分子名称: FERREDOXIN-NADP(H) REDUCTASE, FLAVIN-ADENINE DINUCLEOTIDE, heptyl 1-thio-beta-D-glucopyranoside, ... (6 entities in total)
• 機能のキーワード: ferredoxin(flavodoxin)-nadp(h) reductase, flavoproteins, electron transfer, rhodobacter capsulatus, oxidoreductase
• 由来する生物種: RHODOBACTER CAPSULATUS
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 32289.75

構造登録者

Perez-Dorado, J.I.,Hermoso, J.A.,Nogues, I.,Frago, S.,Bittel, C.,Mayhew, S.G.,Gomez-Moreno, C.,Medina, M.,Cortez, N.,Carrillo, N. (登録日: 2004-12-23, 公開日: 2005-09-07, 最終更新日: 2023-12-13)

主引用文献

Nogues, I.,Perez-Dorado, J.I.,Frago, S.,Bittel, C.,Mayhew, S.G.,Gomez-Moreno, C.,Hermoso, J.A.,Medina, M.,Cortez, N.,Carrillo, N.
The Ferredoxin-Nadp(H) Reductase from Rhodobacter Capsulatus: Molecular Structure and Catalytic Mechanism
Biochemistry, 44:11730-, 2005

PubMed Abstract: The photosynthetic bacterium Rhodobacter capsulatus contains a ferredoxin (flavodoxin)-NADP(H) oxidoreductase (FPR) that catalyzes electron transfer between NADP(H) and ferredoxin or flavodoxin. The structure of the enzyme, determined by X-ray crystallography, contains two domains harboring the FAD and NADP(H) binding sites, as is typical of the FPR structural family. The FAD molecule is in a hairpin conformation in which stacking interactions can be established between the dimethylisoalloxazine and adenine moieties. The midpoint redox potentials of the various transitions undergone by R. capsulatus FPR were similar to those reported for their counterparts involved in oxygenic photosynthesis, but its catalytic activity is orders of magnitude lower (1-2 s(-)(1) versus 200-500 s(-)(1)) as is true for most of its prokaryotic homologues. To identify the mechanistic basis for the slow turnover in the bacterial enzymes, we dissected the R. capsulatus FPR reaction into hydride transfer and electron transfer steps, and determined their rates using stopped-flow methods. Hydride exchange between the enzyme and NADP(H) occurred at 30-150 s(-)(1), indicating that this half-reaction does not limit FPR activity. In contrast, electron transfer to flavodoxin proceeds at 2.7 s(-)(1), in the range of steady-state catalysis. Flavodoxin semiquinone was a better electron acceptor for FPR than oxidized flavodoxin under both single turnover and steady-state conditions. The results indicate that one-electron reduction of oxidized flavodoxin limits the enzyme activity in vitro, and support the notion that flavodoxin oscillates between the semiquinone and fully reduced states when FPR operates in vivo.

PubMed: 16128574
DOI: 10.1021/BI0508183

実験手法

X-RAY DIFFRACTION (1.68 Å)