Ferredoxin competes with bacterial frataxin in binding to the desulfurase IscS.
Ferredoxin competes with bacterial frataxin in binding to the desulfurase IscS.
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DOI：
10.1074/jbc.m113.480327
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发表时间：
2013-08-23
期刊：
影响因子：
--
通讯作者：
Pastore A
中科院分区：
文献类型：
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作者：
Yan R;Konarev PV;Iannuzzi C;Adinolfi S;Roche B;Kelly G;Simon L;Martin SR;Py B;Barras F;Svergun DI;Pastore A
背景：细菌的ISC操纵子含有一个确切作用未知的铁氧还蛋白和一个脱硫酶。结果：我们对大肠杆菌铁氧还蛋白与脱硫酶ISCS的络合物进行了结构表征。结论：我们发现铁氧还蛋白在活性部位附近占据凹槽。意义：我们的结果揭示了铁-硫团簇生物发生的机制。细菌铁硫簇(ISC)操纵子是从细菌到灵长类高度保守的一种重要机制，负责铁硫簇的生物发生。在它的组成中，有为簇形成提供硫的脱硫酶ISCS的基因，以及一种特殊的铁还蛋白(FDX)，其作用尚不清楚。初步证据表明，ISCS和FDX相互作用，但对结合部位和相互作用的作用一无所知。在这里，我们使用生物物理工具和诱变的组合来表征相互作用。通过基于实验约束对FDX·ISCS复合体进行建模，我们发现FDX竞争CyaY的结合部位，并位于靠近酶活性部位的空腔中。CyaY是Frataxin的细菌同源物。通过对细菌的体内诱变，我们证明了相互作用表面对于簇形成的重要性。我们的数据首次为FDX在簇组装中的作用提供了结构性的见解。
Background: The bacterial Isc operon contains a ferredoxin whose precise role is unknown and a desulfurase enzyme. Results: We have structurally characterized the complex of Escherichia coli ferredoxin with the desulfurase IscS. Conclusion: We show that ferredoxin occupies a groove close to the active site. Significance: Our results shed light into the mechanism of iron-sulfur cluster biogenesis. The bacterial iron-sulfur cluster (isc) operon is an essential machine that is highly conserved from bacteria to primates and responsible for iron-sulfur cluster biogenesis. Among its components are the genes for the desulfurase IscS that provides sulfur for cluster formation, and a specialized ferredoxin (Fdx) whose role is still unknown. Preliminary evidence suggests that IscS and Fdx interact but nothing is known about the binding site and the role of the interaction. Here, we have characterized the interaction using a combination of biophysical tools and mutagenesis. By modeling the Fdx·IscS complex based on experimental restraints we show that Fdx competes for the binding site of CyaY, the bacterial ortholog of frataxin and sits in a cavity close to the enzyme active site. By in vivo mutagenesis in bacteria we prove the importance of the surface of interaction for cluster formation. Our data provide the first structural insights into the role of Fdx in cluster assembly.