REDUCTION AND MOBILIZATION OF IRON BY A NAD(P)H - FLAVIN OXIDOREDUCTASE FROM ESCHERICHIA-COLI
REDUCTION AND MOBILIZATION OF IRON BY A NAD(P)H - FLAVIN OXIDOREDUCTASE FROM ESCHERICHIA-COLI
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DOI：
10.1111/j.1432-1033.1993.tb17591.x
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发表时间：
1993-02-01
期刊：
影响因子：
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通讯作者：
FONTECAVE, M
中科院分区：
文献类型：
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作者：
COVES, J;FONTECAVE, M
铁是所有活细胞的必需元素。微生物对铁的溶解、吸收和运输是由称为铁载体的高效且特异的 Fe3+ 螯合剂控制的。然而，从铁铁载体中动员铁的机制仍然是个谜。在这里，我们证明大肠杆菌含有强大的酶系统，可减少铁铁载体。铁载体对二价铁的亲和力要低得多，然后可以将其释放。该系统之前已被纯化并表征为 NAD(P)H：黄素氧化还原酶 [Fontecave, M.、Eliasson, R. 和 Reichard, P. (1987) J. Biol.。化学。 262、12325-12331）]。它通过 NADH 或 NADPH 催化游离黄素、FMN、FAD 或核黄素的还原。还原的黄素反过来将其电子转移至生理性铁络合物：铁铁载体、柠檬酸铁和铁蛋白。该反应受到分子氧的抑制，并受到 Fe2+ 受体（例如铁嗪或无铁形式的核糖核苷酸还原酶亚基 R2）的极大刺激。我们认为，细胞中铁铁载体中铁的减少和动员可能受到生理亚铁陷阱（例如脱辅基蛋白）的存在的调节。
Iron is an essential element in all living cells. Solubilization, uptake and transport of iron by microorganisms is controlled by highly efficient and specific Fe3+-chelating agents named siderophores. However, mechanisms of mobilization of iron from ferrisiderophores are still enigmatic. Here, we demonstrate that Escherichia coli contains a powerful enzymatic system for the reduction of ferrisiderophores. Siderophores have a much lower affinity for ferrous iron, which then can be liberated. This system has been previously purified and characterized as a NAD(P)H:flavin oxidoreductase [Fontecave, M., Eliasson, R. and Reichard, P. (1987) J. Biol. Chem. 262, 12325-12331)]. It catalyzes the reduction of free flavins, FMN, FAD or riboflavin by NADH or NADPH. Reduced flavins, in turn transfer their electrons to physiological ferric complexes: ferrisiderophores, ferric citrate and ferritins. The reaction is inhibited by molecular oxygen and greatly stimulated by Fe2+-acceptors such as ferrozine or the iron-free form of ribonucleotide reductase subunit R2. We suggest that the reduction and the mobilization of iron from ferrisiderophores in the cell might be regulated by the presence of physiological ferrous traps such as apoproteins.