Laboratoire de Chimie Bactérienne, UMR 7283 Aix-Marseille Université-CNRS, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
Mol Microbiol. 2012 Oct;86(1):155-71. doi: 10.1111/j.1365-2958.2012.08181.x. Epub 2012 Sep 12.
Biosynthesis of iron-sulphur (Fe-S) proteins is catalysed by multi-protein systems, ISC and SUF. However, 'non-ISC, non-SUF' Fe-S biosynthesis factors have been described, both in prokaryotes and eukaryotes. Here we report in vitro and in vivo investigations of such a 'non-ISC, non SUF' component, the Nfu proteins. Phylogenomic analysis allowed us to define four subfamilies. Escherichia coli NfuA is within subfamily II. Most members of this subfamily have a Nfu domain fused to a 'degenerate' A-type carrier domain (ATC*) lacking Fe-S cluster co-ordinating Cys ligands. The Nfu domain binds a [4Fe-4S] cluster while the ATC* domain interacts with NuoG (a complex I subunit) and aconitase B (AcnB). In vitro, holo-NfuA promotes maturation of AcnB. In vivo, NfuA is necessary for full activity of complex I under aerobic growth conditions, and of AcnB in the presence of superoxide. NfuA receives Fe-S clusters from IscU/HscBA and SufBCD scaffolds and eventually transfers them to the ATCs IscA and SufA. This study provides significant information on one of the Fe-S biogenesis factors that has been often used as a building block by ISC and/or SUF synthesizing organisms, including bacteria, plants and animals.
铁硫（Fe-S）蛋白的生物合成由多蛋白系统 ISC 和 SUF 催化。然而，在原核生物和真核生物中都已经描述了“非 ISC、非 SUF”Fe-S 生物合成因子。在这里，我们报告了对这样一种“非 ISC、非 SUF”成分 Nfu 蛋白的体外和体内研究。系统发育分析使我们能够定义四个亚科。大肠杆菌 NfuA 属于亚科 II。该亚科的大多数成员都具有与“退化”A型载体结构域（ATC*）融合的 Nfu 结构域，该结构域缺乏 Fe-S 簇配位半胱氨酸配体。Nfu 结构域结合 [4Fe-4S]簇，而 ATC*结构域与复合物 I 亚基 NuoG 和 aconitase B (AcnB) 相互作用。在体外，全酶 NfuA 促进 AcnB 的成熟。在体内，在需氧生长条件下，NfuA 是复合物 I 完全活性所必需的，并且在超氧存在下是 AcnB 所必需的。NfuA 从 IscU/HscBA 和 SufBCD 支架接收 Fe-S 簇，并最终将其转移到 IscA 和 SufA 的 ATCs 上。这项研究提供了关于 Fe-S 生物发生因子之一的重要信息，该因子经常被 ISC 和/或 SUF 合成生物体（包括细菌、植物和动物）用作构建块。
