Three Aromatic Residues are Required for Electron Transfer during Iron Mineralization in Bacterioferritin.
Three Aromatic Residues are Required for Electron Transfer during Iron Mineralization in Bacterioferritin.
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DOI：
10.1002/anie.201507486
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发表时间：
2015-12-01
期刊：
影响因子：
--
通讯作者：
Le Brun NE
中科院分区：
文献类型：
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作者：
Bradley JM;Svistunenko DA;Lawson TL;Hemmings AM;Moore GR;Le Brun NE
铁蛋白是铁储存蛋白，通过二铁亚铁氧化酶位点的活性催化铁氧化和矿化，克服了铁的毒性和生物利用度差的问题。与其他铁蛋白不同，大肠杆菌铁蛋白 (EcBFR) 的氧化二 Fe3+ 位点是稳定的，因此不会充当将 Fe3+ 转移到存储腔中的导管，而是充当真正的催化辅助因子，在驱动腔内 Fe2+ 氧化的同时循环其氧化态。在此，我们证明 EcBFR 矿化取决于二铁位点附近的三个芳香族残基，Tyr25、Tyr58 和 Trp133，并且在 Tyr25 上形成瞬时自由基。数据表明，芳香族残基与先前确定的内表面铁位点一起，通过确保将 BFR 腔中 Fe2+ 氧化产生的两个电子同时传递到二价铁催化位点以安全还原 O2，从而促进矿化。
Ferritins are iron storage proteins that overcome the problems of toxicity and poor bioavailability of iron by catalyzing iron oxidation and mineralization through the activity of a diiron ferroxidase site. Unlike in other ferritins, the oxidized di-Fe3+ site of Escherichia coli bacterioferritin (EcBFR) is stable and therefore does not function as a conduit for the transfer of Fe3+ into the storage cavity, but instead acts as a true catalytic cofactor that cycles its oxidation state while driving Fe2+ oxidation in the cavity. Herein, we demonstrate that EcBFR mineralization depends on three aromatic residues near the diiron site, Tyr25, Tyr58, and Trp133, and that a transient radical is formed on Tyr25. The data indicate that the aromatic residues, together with a previously identified inner surface iron site, promote mineralization by ensuring the simultaneous delivery of two electrons, derived from Fe2+ oxidation in the BFR cavity, to the di-ferric catalytic site for safe reduction of O2.