Isolation and some properties of cytochrome c oxidase purified from a bisulfite ion resistant Thiobacillus ferrooxidans strain, OK1-50.
Sulfite ion (HSO3-) is one of the products when elemental sulfur is oxidized by the hydrogen sulfide:ferric ion oxidoreductase of Thiobacillus ferrooxidans AP19-3. Under the conditions in which HSO3- is accumulated in the cells, the iron oxidase of this bacterium was strongly inhibited by HSO3-. Since cytochrome c oxidase is one of the most important components of the iron oxidase enzyme system in T. ferrooxidans, effects of HSO3- on cytochrome c oxidase activity were studied with the plasma membranes of HSO3(-)-resistant and -sensitive strains of T. ferrooxidans, OK1-50 and AP19-3. The enzyme activity of AP19-3 compared with OK1-50 was strongly inhibited by HSO3-. To investigate the inhibition mechanism of HSO3- in T. ferrooxidans, cytochrome c oxidases were purified from both strains to an electrophoretically homogeneous state. Cytochrome c oxidase activity of a purified OK1-50 enzyme was not inhibited by 5 mM HSO3-. In contrast, the same concentration of HSO3- inhibited the enzyme activity of AP19-3 50%, indicating that the cytochrome c oxidase of OK1-50 was more resistant to HSO3- than that of AP19-3. Cytochrome c oxidases purified from both strains were composed of three subunits. However, the molecular weight of the largest subunit differed between OK1-50 and AP19-3. Apparent molecular weights of the three subunits of cytochrome c oxidases were 53,000, 24,000, and 19,000 for strain AP19-3 and 55,000, 24,000, and 19,000 for strain OK1-50, respectively.
Iwahori
K
K
Department of Biological Function and Genetic Resources Science, Faculty of Agriculture, Okayama University, Japan.
Kamimura
K
K
Sugio
T
T
D004352:Drug Resistance, Microbial; D003576:Electron Transport Complex IV / Q000302:isolation & purification*; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry; D013045:Species Specificity; D013053:Spectrophotometry; D013447:Sulfites / Q000494:pharmacology*; D013855:Thiobacillus / Q000201:enzymology*
D010446:Peptide Fragments; D013447:Sulfites; D003576:Electron Transport Complex IV; C042345:hydrogen sulfite