Sulfite oxidation catalyzed by aa(3)-type cytochrome c oxidase in Acidithiobacillus ferrooxidans.
Sulfite is produced as a toxic intermediate during Acidithiobacillus ferrooxidans sulfur oxidation. A. ferrooxidans D3-2, which posseses the highest copper bioleaching activity, is more resistant to sulfite than other A. ferrooxidans strains, including ATCC 23270. When sulfite oxidase was purified homogeneously from strain D3-2, the oxidized and reduced forms of the purified sulfite oxidase absorption spectra corresponded to those of A. ferrooxidans aa(3)-type cytochrome c oxidase. The confirmed molecular weights of the α-subunit (52.5 kDa), the β-subunit (25 kDa), and the γ-subunit (20 kDa) of the purified sulfite oxidase and the N-terminal amino acid sequences of the γ-subunit of sulfite oxidase (AAKKG) corresponded to those of A. ferrooxidans ATCC 23270 cytochrome c oxidase. The sulfite oxidase activities of the iron- and sulfur-grown A. ferrooxidans D3-2 were much higher than those cytochrome c oxidases purified from A. ferrooxidans strains ATCC 23270, MON-1 and AP19-3. The activities of sulfite oxidase purified from iron- and sulfur-grown strain D3-2 were completely inhibited by an antibody raised against a purified A. ferrooxidans MON-1 aa(3)-type cytochrome c oxidase. This is the first report to indicate that aa(3)-type cytochrome c oxidase catalyzed sulfite oxidation in A. ferrooxidans.
Division of Bioscience, Graduate School of Natural Science and Technology, Okayama University, Japan. sugio@cc.okayama-u.ac.jp
Tsuyoshi
T
Sugio
Ami
A
Ako
Fumiaki
F
Takeuchi
D042763:Acidithiobacillus / Q000201:enzymology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002384:Catalysis; D003576:Electron Transport Complex IV / Q000378:metabolism*; D010084:Oxidation-Reduction; D013447:Sulfites / Q000378:metabolism*
D001426:Bacterial Proteins; D013447:Sulfites; D003576:Electron Transport Complex IV