PDF(Pubmed)
Abstract：
In mitochondria, cysteine desulfurase (Nfs1) plays a central role in the biosynthesis of iron-sulfur (FeS) clusters, cofactors critical for activity of many cellular proteins. Nfs1 functions both as a sulfur donor for cluster assembly and as a binding platform for other proteins functioning in the process. These include not only the dedicated scaffold protein (Isu1) on which FeS clusters are synthesized but also accessory FeS cluster biogenesis proteins frataxin (Yfh1) and ferredoxin (Yah1). Yfh1 has been shown to activate cysteine desulfurase enzymatic activity, whereas Yah1 supplies electrons for the persulfide reduction. While Yfh1 interaction with Nfs1 is well understood, the Yah1-Nfs1 interaction is not. Here, based on the results of biochemical experiments involving purified WT and variant proteins, we report that in Saccharomyces cerevisiae, Yah1 and Yfh1 share an evolutionary conserved interaction site on Nfs1. Consistent with this notion, Yah1 and Yfh1 can each displace the other from Nfs1 but are inefficient competitors when a variant with an altered interaction site is used. Thus, the binding mode of Yah1 and Yfh1 interacting with Nfs1 in mitochondria of S. cerevisiae resembles the mutually exclusive binding of ferredoxin and frataxin with cysteine desulfurase reported for the bacterial FeS cluster assembly system. Our findings are consistent with the generally accepted scenario that the mitochondrial FeS cluster assembly system was inherited from bacterial ancestors of mitochondria.
摘要：
在线粒体中，半胱氨酸脱硫酶（Nfs1）在铁硫（FeS）簇的生物合成中起着核心作用，对许多细胞蛋白的活性至关重要的辅因子。Nfs1既充当簇组装的硫供体，又充当该过程中其他蛋白质的结合平台。这些不仅包括合成FeS簇的专用支架蛋白（Isu1），还包括辅助FeS簇生物发生蛋白共济失调蛋白（Yfh1）和铁氧还蛋白（Yah1）。Yfh1已被证明可以激活半胱氨酸脱硫酶的酶活性，而Yah1为过硫化物还原提供电子。虽然Yfh1与Nfs1的相互作用是众所周知的，Yah1-Nfs1相互作用不是。这里,基于涉及纯化的WT和变异蛋白的生化实验结果，我们报告说，在酿酒酵母中，Yah1和Yfh1在Nfs1上共享一个进化保守的相互作用位点。与这个概念一致，Yah1和Yfh1可以各自从Nfs1取代另一个，但当使用具有改变的相互作用位点的变体时，它们是低效的竞争者。因此，酿酒酵母线粒体中Yah1和Yfh1与Nfs1相互作用的结合模式类似于细菌FeS簇组装系统报道的铁氧还蛋白和共济失调蛋白与半胱氨酸脱硫酶的互斥结合。我们的发现与普遍接受的情况一致，即线粒体FeS簇组装系统是从线粒体的细菌祖先遗传而来的。
