Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina.
Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina.
Biochimie. 2019 Jan;156:118-122. doi: 10.1016/j.biochi.2018.10.009. Epub 2018 Oct 18.
Frataxin plays a key role in cellular iron homeostasis of different organisms. It is engaged in several activities at the FeS cluster assembly machinery and it is also involved in heme biosynthesis. In plants, two genes encoding ferrochelatases (FC1 and FC2) catalyze the incorporation of iron into protoporphyrin IX in the last stage of heme synthesis in chloroplasts. Despite ferrochelatases are absent from other cell compartments, a remaining ferrochelatase activity has been observed in plant mitochondria. Here we analyze the possibility that frataxin acts as the iron donor to protoporphyrin IX for the synthesis of heme groups in plant mitochondria. Our findings show that frataxin catalyzes the formation of heme in vitro when it is incubated with iron and protoporphyrin IX. When frataxin is combined with AtNFS1 and AtISD11 the ferrochelatse activity is increased. These results suggest that frataxin could be the iron donor in the final step of heme synthesis in plant mitochondria, and constitutes an important advance in the elucidation of the mechanisms of heme synthesis in plants.
铁蛋白在不同生物体的细胞铁稳态中发挥关键作用。它参与铁硫簇组装机制的几种活动，也参与血红素生物合成。在植物中，两个编码亚铁螯合酶（FC1 和 FC2）的基因在叶绿体中血红素合成的最后阶段催化铁掺入原卟啉 IX 中。尽管亚铁螯合酶不存在于其他细胞区室中，但在植物线粒体中仍观察到残留的亚铁螯合酶活性。在这里，我们分析了铁蛋白作为铁供体将原卟啉 IX 用于植物线粒体中血红素合成的可能性。我们的研究结果表明，当铁蛋白与铁和原卟啉 IX 孵育时，它可在体外催化血红素的形成。当铁蛋白与 AtNFS1 和 AtISD11 结合时，亚铁螯合酶活性增加。这些结果表明，铁蛋白可能是植物线粒体中血红素合成最后一步的铁供体，这是阐明植物中血红素合成机制的重要进展。
