Ferrous iron oxidation in moderately thermophilic acidophile Sulfobacillus sibiricus N1(T).
The iron-oxidizing system of a moderately thermophilic, extremely acidophilic, gram-positive mixotroph, Sulfobacillus sibiricus N1(T), was studied by spectroscopic, high-performance liquid chromatography and inhibitory analyses. Hemes B, A, and O were detected in membranes of S. sibiricus N1(T). It is proposed that the electron transport chain from Fe²(+) to O₂ is terminated by 2 physiological oxidases: aa₃-type cytochrome, which dominates in the early-exponential phase of growth, and bo₃-type cytochrome, whose role in iron oxidation becomes more prominent upon growth of the culture. Both oxidases were sensitive to cyanide and azide. Cytochrome aa₃ was more sensitive to cyanide and azide, with K(i) values of 4.1 and 2.5 µmol·L⁻¹, respectively, compared with K(i) values for cytochrome bo₃, which were 9.5 µmol·L⁻¹ for cyanide and 7.0 µmol·L⁻¹ for azide. This is the first evidence for the participation of a bo₃-type oxidase in ferrous iron oxidation. The respiratory chain of the mixotroph contains, in addition to the 2 terminal oxidases, a membrane-bound cytochrome b₅₇₃.
Department of Microbiology, Moscow State University, Russian Federation. dinarieva@mail.ru
Tatiana Y
TY
Dinarieva
Anna E
AE
Zhuravleva
Oksana A
OA
Pavlenko
Iraida A
IA
Tsaplina
Alexander I
AI
Netrusov
D001386:Azides / Q000494:pharmacology; D056449:Bacillales; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003486:Cyanides / Q000494:pharmacology; D003580:Cytochromes / Q000737:chemistry / Q000378:metabolism; D004579:Electron Transport; D004734:Energy Metabolism; D005296:Ferrous Compounds / Q000378:metabolism*; D006094:Gram-Positive Bacteria / Q000378:metabolism*; D006418:Heme / Q000032:analysis; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D013057:Spectrum Analysis; D013379:Substrate Specificity
D001386:Azides; D003486:Cyanides; D003580:Cytochromes; D005296:Ferrous Compounds; D006418:Heme; D007501:Iron; D010088:Oxidoreductases; C034236:ferrous oxide