Redox Control of the Human Iron-Sulfur Repair Protein MitoNEET Activity via Its Iron-Sulfur Cluster
Redox Control of the Human Iron-Sulfur Repair Protein MitoNEET Activity via Its Iron-Sulfur Cluster
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DOI：
10.1074/jbc.m115.711218
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发表时间：
2016-04-01
影响因子：
4.8
通讯作者：
Bouton, Cecile
中科院分区：
文献类型：
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作者：
Golinelli-Cohen, Marie-Pierre;Lescop, Ewen;Bouton, Cecile
人类mitoNEET（mNT）是哺乳动物线粒体外膜的第一个被鉴定的Fe-S蛋白。最近，mNT已被牵连在细胞内铁稳态的关键调节细胞溶质Fe-S修复。在这里，我们的目标是破译mNT触发其Fe-S修复能力的机制。通过使用严格控制的反应结合互补的光谱方法，我们已经确定了由两个氧化还原状态的mNT簇和分子氧簇转移和蛋白质的稳定性所发挥的不同作用。我们明确地表明，只有氧化状态的NT簇触发集群转移到一个通用的受体蛋白，分子氧既不需要集群转移反应，也不影响转移速率。在无脱辅基受体的情况下，大部分氧化的holo-mNT形式在低氧张力下转化回还原的holo-mNT。而还原态的holo-mNT，其[2Fe-2S]（+）结构与氧化态的相似，不容易丢失或转移，因此我们的研究结果表明，mNT是通过铁基氧化还原开关机制来调节其簇的转移的。氧化态是“活性态”，其迅速反应以独立于分子氧引发Fe-S转移，而还原态是“休眠形式”。“最后，我们提出mNT的氧化还原传感功能是细胞适应性反应的关键组成部分，有助于应激敏感的Fe-S蛋白从氧化损伤中恢复。
Human mitoNEET (mNT) is the first identified Fe-S protein of the mammalian outer mitochondrial membrane. Recently, mNT has been implicated in cytosolic Fe-S repair of a key regulator of cellular iron homeostasis. Here, we aimed to decipher the mechanism by which mNT triggers its Fe-S repair capacity. By using tightly controlled reactions combined with complementary spectroscopic approaches, we have determined the differential roles played by both the redox state of the mNT cluster and dioxygen in cluster transfer and protein stability. We unambiguously demonstrated that only the oxidized state of them NT cluster triggers cluster transfer to a generic acceptor protein and that dioxygen is neither required for the cluster transfer reaction nor does it affect the transfer rate. In the absence of apo-acceptors, a large fraction of the oxidized holo-mNT form is converted back to reduced holo-mNT under low oxygen tension. Reduced holo-mNT, which holds a [2Fe-2S](+) with a global protein fold similar to that of the oxidized form is, by contrast, resistant in losing its cluster or in transferring it. Our findings thus demonstrate that mNT uses an iron-based redox switch mechanism to regulate the transfer of its cluster. The oxidized state is the "active state," which reacts promptly to initiate Fe-Stransfer independently of dioxygen, whereas the reduced state is a "dormant form." Finally, we propose that the redox-sensing function of mNT is a key component of the cellular adaptive response to help stress-sensitive Fe-S proteins recover from oxidative injury.