Teixeira M, Batista R, Campos AP, Gomes C, Mendes J, Pacheco I, Anemuller S, Hagen WR. A seven-iron ferredoxin from the thermoacidophilic archaeon Desulfurolobus ambivalens.
EUROPEAN JOURNAL OF BIOCHEMISTRY 1995;
227:322-7. [PMID:
7851403 DOI:
10.1111/j.1432-1033.1995.tb20392.x]
[Citation(s) in RCA: 61] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A seven-iron ferredoxin was isolated from aerobically grown cells of the hyperthermoacidophilic archaeon Desulfurolobus ambivalens (DSM 3772). The protein is monomeric, with an apparent molecular mass of 15 kDa and contains 7 iron atoms/molecule. The N-terminal sequence shows a large similarity (70% identity) with that of the ferredoxin isolated from the archaeon Sulfolobus acidocaldarius. The EPR characteristics in both the native (oxidized) and dithionite-reduced states of this protein allowed an unequivocal identification of a [3Fe-4S]1+/0 center, with a reduction potential of -270 +/- 20 mV, at pH 7.5. The protein also contains a [4Fe-4S]2+/1+ center with a very low reduction potential (Eo = -540 mV, pH 7.0), which yields a rhombic EPR spectrum upon reduction with sodium dithionite at high pH. The reduction potentials of both centers are slightly pH dependent between pH 6 and 9. The [3Fe-4S] ferredoxin center is able to accept electrons from pyruvate oxidase and NADH oxidase isolated from D. ambivalens. This ferredoxin is present in large amounts (at least 130 mg/kg wet cells), which allowed the unequivocal observation of oxidized [3Fe-4S] clusters in intact D. ambivalens cells.
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