7CQY

Tetrathionate hydrolase from Acidithiobacillus ferrooxidans mutant - D325N

Summary for 7CQY

• Entry DOI: 10.2210/pdb7cqy/pdb
• Descriptor: Tetrathionate hydrolase, SULFATE ION (3 entities in total)
• Functional Keywords: tetrathionate, hydrolase
• Biological source: Acidithiobacillus ferrooxidans
• Total number of polymer chains: 6
• Total formula weight: 301142.04

Authors

Tamada, T.,Hirano, Y. (deposition date: 2020-08-12, release date: 2021-01-27, Last modification date: 2023-11-29)

Primary citation

Kanao, T.,Hase, N.,Nakayama, H.,Yoshida, K.,Nishiura, K.,Kosaka, M.,Kamimura, K.,Hirano, Y.,Tamada, T.
Reaction mechanism of tetrathionate hydrolysis based on the crystal structure of tetrathionate hydrolase from Acidithiobacillus ferrooxidans.
Protein Sci., 30:328-338, 2020

PubMed Abstract: Tetrathionate hydrolase (4THase) plays an important role in dissimilatory sulfur oxidation in the acidophilic iron- and sulfur-oxidizing bacterium Acidithiobacillus ferrooxidans. The structure of recombinant 4THase from A. ferrooxidans (Af-Tth) was determined by X-ray crystallography to a resolution of 1.95 Å. Af-Tth is a homodimer, and its monomer structure exhibits an eight-bladed β-propeller motif. Two insertion loops participate in dimerization, and one loop forms a cavity with the β-propeller region. We observed unexplained electron densities in this cavity of the substrate-soaked structure. The anomalous difference map generated using diffraction data collected at a wavelength of 1.9 Å indicated the presence of polymerized sulfur atoms. Asp325, a highly conserved residue among 4THases, was located near the polymerized sulfur atoms. 4THase activity was completely abolished in the site-specific Af-Tth D325N variant, suggesting that Asp325 plays a crucial role in the first step of tetrathionate hydrolysis. Considering that the Af-Tth reaction occurs only under acidic pH, Asp325 acts as an acid for the tetrathionate hydrolysis reaction. The polymerized sulfur atoms in the active site cavity may represent the intermediate product in the subsequent step.

PubMed: 33103311
DOI: 10.1002/pro.3984

Experimental method

X-RAY DIFFRACTION (2.8003577513 Å)