title: Characterization of a novel thiosulfate dehydrogenase from a marine acidophilic sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH.
abstract: A marine acidophilic sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH, was isolated to develop a bioleaching process for NaCl-containing sulfide minerals. Because the sulfur moiety of sulfide minerals is metabolized to sulfate via thiosulfate as an intermediate, we purified and characterized the thiosulfate dehydrogenase (TSD) from strain SH. The enzyme had an apparent molecular mass of 44 kDa and was purified 71-fold from the solubilized membrane fraction. Tetrathionate was the product of the TSD-oxidized thiosulfate and ferricyanide or ubiquinone was the electron acceptor. Maximum enzyme activity was observed at pH 4.0, 40 °C, and 200 mM NaCl. To our knowledge, this is the first report of NaCl-stimulated TSD activity. TSD was structurally different from the previously reported thiosulfate-oxidizing enzymes. In addition, TSD activity was strongly inhibited by 2-heptyl-4-hydroxy-quinoline N-oxide, suggesting that the TSD is a novel thiosulfate:quinone reductase.
authors.affiliation: a Division of Agricultural and Life Science, Graduate School of Environmental and Life Science , Okayama University , Okayama , Japan.
authors.forename: Sultana
authors.initials: S
authors.lastname: Sharmin
authors.affiliation: a Division of Agricultural and Life Science, Graduate School of Environmental and Life Science , Okayama University , Okayama , Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Yoshino
authors.affiliation: a Division of Agricultural and Life Science, Graduate School of Environmental and Life Science , Okayama University , Okayama , Japan.
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Kanao
authors.affiliation: a Division of Agricultural and Life Science, Graduate School of Environmental and Life Science , Okayama University , Okayama , Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kamimura
mesh_terms: D013856:Acidithiobacillus thiooxidans / Q000201:enzymology* / Q000235:genetics; D059001:Aquatic Organisms; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D002462:Cell Membrane / Q000737:chemistry; D004583:Electrons; D005292:Ferricyanides / Q000737:chemistry; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D006912:Hydroxyquinolines / Q000737:chemistry; D007700:Kinetics; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D012965:Sodium Chloride / Q000737:chemistry; D013379:Substrate Specificity; D013885:Thiosulfates / Q000737:chemistry; D014451:Ubiquinone / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D005292:Ferricyanides; D006912:Hydroxyquinolines; D008565:Membrane Proteins; D013885:Thiosulfates; D014451:Ubiquinone; C007931:hexacyanoferrate III; C001333:2-(n-heptyl)-4-hydroxyquinoline N-oxide; D012965:Sodium Chloride; D010088:Oxidoreductases; C432587:thiosulfate dehydrogenase
keywords: Acidithiobacillus thiooxidans; acidophile; marine; thiosulfate dehydrogenase