Crystal structure studies on sulfur oxygenase reductase from Acidianus tengchongensis.
Sulfur oxygenase reductase (SOR) simultaneously catalyzes oxidation and reduction of elemental sulfur to produce sulfite, thiosulfate, and sulfide in the presence of molecular oxygen. In this study, crystal structures of wild type and mutants of SOR from Acidianus tengchongensis (SOR-AT) in two different crystal forms were determined and it was observed that 24 identical SOR monomers form a hollow sphere. Within the icosatetramer sphere, the tetramer and trimer channels were proposed as the paths for the substrate and products, respectively. Moreover, a comparison of SOR-AT with SOR-AA (SOR from Acidianus ambivalens) structures showed that significant differences existed at the active site. Firstly, Cys31 is not persulfurated in SOR-AT structures. Secondly, the iron atom is five-coordinated rather than six-coordinated, since one of the water molecules ligated to the iron atom in the SOR-AA structure is lost. Consequently, the binding sites of substrates and a hypothetical catalytic process of SOR were proposed.
Li
Mei
M
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, PR China.
Chen
Zhiwei
Z
Zhang
Pingfeng
P
Pan
Xiaowei
X
Jiang
Chengying
C
An
Xiaomin
X
Liu
Shuangjiang
S
Chang
Wenrui
W
D041541:Acidianus / Q000201:enzymology*; D019843:Archaeal Proteins / Q000737:chemistry*; D001665:Binding Sites; D002384:Catalysis; D003461:Crystallography; D010088:Oxidoreductases / Q000737:chemistry*; D011487:Protein Conformation
D019843:Archaeal Proteins; D010088:Oxidoreductases; C074883:polysulfide reductase