2NNF

Structure of the sulfur carrier protein SoxY from Chlorobium limicola f thiosulfatophilum

2NNF の概要

• エントリーDOI: 10.2210/pdb2nnf/pdb
• 関連するPDBエントリー: 2NNC
• 分子名称: Sulfur covalently-binding protein, PHOSPHATE ION (3 entities in total)
• 機能のキーワード: sulfur binding protein, sox, beta sandwich, green sulfur bacterium, ligand binding protein
• 由来する生物種: Chlorobium limicola
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 26205.30

構造登録者

Stout, J.,Van Driessche, G.,Savvides, S.N.,Van Beeumen, J. (登録日: 2006-10-24, 公開日: 2007-03-13, 最終更新日: 2023-12-27)

主引用文献

Stout, J.,Van Driessche, G.,Savvides, S.N.,Van Beeumen, J.
X-ray crystallographic analysis of the sulfur carrier protein SoxY from Chlorobium limicola f. thiosulfatophilum reveals a tetrameric structure.
Protein Sci., 16:589-601, 2007

PubMed Abstract: Dissimilatory oxidation of thiosulfate in the green sulfur bacterium Chlorobium limicola f. thiosulfatophilum is carried out by the ubiquitous sulfur-oxidizing (Sox) multi-enzyme system. In this system, SoxY plays a key role, functioning as the sulfur substrate-binding protein that offers its sulfur substrate, which is covalently bound to a conserved C-terminal cysteine, to another oxidizing Sox enzyme. Here, we report the crystal structures of a stand-alone SoxY protein of C. limicola f. thiosulfatophilum, solved at 2.15 A and 2.40 A resolution using X-ray diffraction data collected at 100 K and room temperature, respectively. The structure reveals a monomeric Ig-like protein, with an N-terminal alpha-helix, that oligomerizes into a tetramer via conserved contact regions between the monomers. The tetramer can be described as a dimer of dimers that exhibits one large hydrophobic contact region in each dimer and two small hydrophilic interface patches in the tetramer. At the tetramer interface patch, two conserved redox-active C-terminal cysteines form an intersubunit disulfide bridge. Intriguingly, SoxY exhibits a dimer/tetramer equilibrium that is dependent on the redox state of the cysteines and on the type of sulfur substrate component bound to them. Taken together, the dimer/tetramer equilibrium, the specific interactions between the subunits in the tetramer, and the significant conservation level of the interfaces strongly indicate that these SoxY oligomers are biologically relevant.

PubMed: 17327392
DOI: 10.1110/ps.062633607

実験手法

X-RAY DIFFRACTION (2.39 Å)