4V2K

Crystal structure of the thiosulfate dehydrogenase TsdA in complex with thiosulfate

4V2K の概要

• エントリーDOI: 10.2210/pdb4v2k/pdb
• 分子名称: THIOSULFATE DEHYDROGENASE, HEME C, THIOSULFATE, ... (4 entities in total)
• 機能のキーワード: oxidoreductase, cytochrome c, his/cys heme, disulfide formation, cysteine modification
• 由来する生物種: ALLOCHROMATIUM VINOSUM
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 28407.53

構造登録者

Grabarczyk, D.B.,Chappell, P.E.,Eisel, B.,Johnson, S.,Lea, S.M.,Berks, B.C. (登録日: 2014-10-10, 公開日: 2015-02-18, 最終更新日: 2024-11-06)

主引用文献

Grabarczyk, D.B.,Chappell, P.E.,Eisel, B.,Johnson, S.,Lea, S.M.,Berks, B.C.
Mechanism of Thiosulfate Oxidation in the Soxa Family of Cysteine-Ligated Cytochromes
J.Biol.Chem., 290:9209-, 2015

PubMed Abstract: Thiosulfate dehydrogenase (TsdA) catalyzes the oxidation of two thiosulfate molecules to form tetrathionate and is predicted to use an unusual cysteine-ligated heme as the catalytic cofactor. We have determined the structure of Allochromatium vinosum TsdA to a resolution of 1.3 Å. This structure confirms the active site heme ligation, identifies a thiosulfate binding site within the active site cavity, and reveals an electron transfer route from the catalytic heme, through a second heme group to the external electron acceptor. We provide multiple lines of evidence that the catalytic reaction proceeds through the intermediate formation of a S-thiosulfonate derivative of the heme cysteine ligand: the cysteine is reactive and is accessible to electrophilic attack; cysteine S-thiosulfonate is formed by the addition of thiosulfate or following the reverse reaction with tetrathionate; the S-thiosulfonate modification is removed through catalysis; and alkylating the cysteine blocks activity. Active site amino acid residues required for catalysis were identified by mutagenesis and are inferred to also play a role in stabilizing the S-thiosulfonate intermediate. The enzyme SoxAX, which catalyzes the first step in the bacterial Sox thiosulfate oxidation pathway, is homologous to TsdA and can be inferred to use a related catalytic mechanism.

PubMed: 25673696
DOI: 10.1074/JBC.M114.618025

実験手法

X-RAY DIFFRACTION (1.29 Å)