title: Purification and characterization of sulfide:quinone oxidoreductase from an acidophilic iron-oxidizing bacterium, Acidithiobacillus ferrooxidans.
abstract: Sulfide:quinone oxidoreductase (SQR) was purified from membrane of acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans NASF-1 cells grown on sulfur medium. It was composed of a single polypeptide with an apparent molecular mass of 47 kDa. The apparent K(m) values for sulfide and ubiquinone were 42 and 14 muM respectively. The apparent optimum pH for the SQR activity was about 7.0. A gene encoding a putative SQR of A. ferrooxidans NASF-1 was cloned and sequenced. The gene was expressed in Escherichia coli as a thioredoxin-fusion protein in inclusion bodies in an inactive form. A polyclonal antibody prepared against the recombinant protein reacted immunologically with the purified SQR. Western blotting analysis using the antibody revealed an increased level of SQR synthesis in sulfur-grown A. ferrooxidans NASF-1 cells, implying the involvement of SQR in elemental sulfur oxidation in sulfur-grown A. ferrooxidans NASF-1 cells.
authors.affiliation: Department of Botany and Microbiology, Division of Bioscience, Graduate School of Natural Science and Technology, Okayama University, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Wakai
authors.forename: Mizuho
authors.initials: M
authors.lastname: Tsujita
authors.forename: Mei
authors.initials: M
authors.lastname: Kikumoto
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Manchur
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Kanao
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kamimura
mesh_terms: D042763:Acidithiobacillus / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D002384:Catalysis; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction; D011808:Quinone Reductases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D013455:Sulfur / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D013455:Sulfur; D007501:Iron; D011808:Quinone Reductases; C073412:sulfide quinone reductase