1S3D

ARSENATE REDUCTASE R60A MUTANT FROM E. COLI

1S3D の概要

• エントリーDOI: 10.2210/pdb1s3d/pdb
• 関連するPDBエントリー: 1S3C
• 分子名称: Arsenate reductase, SULFATE ION, CESIUM ION, ... (4 entities in total)
• 機能のキーワード: arsc, reductase, arsenite, arsenate, oxidoreductase
• 由来する生物種: Escherichia coli
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 16464.45

構造登録者

Demel, S.,Edwards, B.F. (登録日: 2004-01-13, 公開日: 2005-02-15, 最終更新日: 2024-04-03)

主引用文献

DeMel, S.,Shi, J.,Martin, P.,Rosen, B.P.,Edwards, B.F.
Arginine 60 in the ArsC arsenate reductase of E. coli plasmid R773 determines the chemical nature of the bound As(III) product.
Protein Sci., 13:2330-2340, 2004

PubMed Abstract: Arsenic is a ubiquitous environmental toxic metal. Consequently, organisms detoxify arsenate by reduction to arsenite, which is then excreted or sequestered. The ArsC arsenate reductase from Escherichia coli plasmid R773, the best characterized arsenic-modifying enzyme, has a catalytic cysteine, Cys 12, in the active site, surrounded by an arginine triad composed of Arg 60, Arg 94, and Arg 107. During the reaction cycle, the native enzyme forms a unique monohydroxyl Cys 12-thiol-arsenite adduct that contains a positive charge on the arsenic. We hypothesized previously that this unstable intermediate allows for rapid dissociation of the product arsenite. In this study, the role of Arg 60 in product formation was evaluated by mutagenesis. A total of eight new structures of ArsC were determined at resolutions between 1.3 A and 1.8 A, with R(free) values between 0.18 and 0.25. The crystal structures of R60K and R60A ArsC equilibrated with the product arsenite revealed a covalently bound Cys 12-thiol-dihydroxyarsenite without a charge on the arsenic atom. We propose that this intermediate is more stable than the monohydroxyarsenite intermediate of the native enzyme, resulting in slow release of product and, consequently, loss of activity.

PubMed: 15295115
DOI: 10.1110/ps.04787204

実験手法

X-RAY DIFFRACTION (1.54 Å)