2DTX

Structure of Thermoplasma acidophilum aldohexose dehydrogenase (AldT) in complex with D-mannose

2DTX の概要

• エントリーDOI: 10.2210/pdb2dtx/pdb
• 関連するPDBエントリー: 2dtd 2dte
• 分子名称: Glucose 1-dehydrogenase related protein, beta-D-mannopyranose, SULFATE ION, ... (4 entities in total)
• 機能のキーワード: rossmann fold, oxidoreductase
• 由来する生物種: Thermoplasma acidophilum
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 58620.72

構造登録者

Yasutake, Y.,Nishiya, Y.,Tamura, N.,Tamura, T. (登録日: 2006-07-18, 公開日: 2007-03-27, 最終更新日: 2024-11-06)

主引用文献

Yasutake, Y.,Nishiya, Y.,Tamura, N.,Tamura, T.
Structural Insights into Unique Substrate Selectivity of Thermoplasma acidophilumd-Aldohexose Dehydrogenase
J.Mol.Biol., 367:1034-1046, 2007

PubMed Abstract: The D-aldohexose dehydrogenase from the thermoacidophilic archaea Thermoplasma acidophilum (AldT) belongs to the short-chain dehydrogenase/reductase (SDR) superfamily and catalyzes the oxidation of several monosaccharides with a preference for NAD(+) rather than NADP(+) as a cofactor. It has been found that AldT is a unique enzyme that exhibits the highest dehydrogenase activity against D-mannose. Here, we describe the crystal structures of AldT in ligand-free form, in complex with NADH, and in complex with the substrate D-mannose, at 2.1 A, 1.65 A, and 1.6 A resolution, respectively. The AldT subunit forms a typical SDR fold with an unexpectedly long C-terminal tail and assembles into an intertwined tetramer. The D-mannose complex structure reveals that Glu84 interacts with the axial C2 hydroxyl group of the bound D-mannose. Structural comparison with Bacillus megaterium glucose dehydrogenase (BmGlcDH) suggests that the conformation of the glutamate side-chain is crucial for discrimination between D-mannose and its C2 epimer D-glucose, and the conformation of the glutamate side-chain depends on the spatial arrangement of nearby hydrophobic residues that do not directly interact with the substrate. Elucidation of the D-mannose recognition mechanism of AldT further provides structural insights into the unique substrate selectivity of AldT. Finally, we show that the extended C-terminal tail completely shuts the substrate-binding pocket of the neighboring subunit both in the presence and absence of substrate. The elaborate inter-subunit interactions between the C-terminal tail and the entrance of the substrate-binding pocket imply that the tail may play a pivotal role in the enzyme activity.

PubMed: 17300803
DOI: 10.1016/j.jmb.2007.01.029

実験手法

X-RAY DIFFRACTION (1.6 Å)