Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
J Biol Chem. 2011 May 6;286(18):15797-805. doi: 10.1074/jbc.M110.201731. Epub 2011 Mar 2.
Iron-sulfur proteins play an essential role in a variety of biologic processes and exist in multiple cellular compartments. The biogenesis of these proteins has been the subject of extensive investigation, and particular focus has been placed on the pathways that assemble iron-sulfur clusters in the different cellular compartments. Iron-only hydrogenase-like protein 1 (IOP1; also known as nuclear prelamin A recognition factor like protein, or NARFL) is a human protein that is homologous to Nar1, a protein in Saccharomyces cerevisiae that, in turn, is an essential component of the cytosolic iron-sulfur protein assembly pathway in yeast. Previous siRNA-induced knockdown studies using mammalian cells point to a similar role for IOP1 in mammals. In the present studies, we pursued this further by knocking out Iop1 in Mus musculus. We find that Iop1 knock-out results in embryonic lethality before embryonic day 10.5. Acute, inducible global knock-out of Iop1 in adult mice results in lethality and significantly diminished activity of cytosolic aconitase, an iron-sulfur protein, in liver extracts. Inducible knock-out of Iop1 in mouse embryonic fibroblasts results in diminished activity of cytosolic but not mitochondrial aconitase and loss of cell viability. Therefore, just as with knock-out of Nar1 in yeast, we find that knock-out of Iop1/Narfl in mice results in lethality and defective cytosolic iron-sulfur cluster assembly. The findings demonstrate an essential role for IOP1 in this pathway.
铁硫蛋白在多种生物过程中发挥着重要作用，存在于多个细胞区室中。这些蛋白质的生物发生一直是广泛研究的主题，特别关注的是在不同细胞区室中组装铁硫簇的途径。铁-only 氢化酶样蛋白 1（IOP1；也称为核前层蛋白 A 识别因子样蛋白，或 NARFL）是一种人类蛋白，与酿酒酵母中的 Nar1 同源，而 Nar1 又是酵母胞质铁硫蛋白组装途径中的必需成分。先前使用哺乳动物细胞的 siRNA 诱导敲低研究表明，IOP1 在哺乳动物中也具有类似的作用。在本研究中，我们通过敲除 Mus musculus 中的 Iop1 进一步研究了这一点。我们发现，Iop1 敲除导致胚胎在第 10.5 天前死亡。在成年小鼠中急性诱导性全局敲除 Iop1 会导致死亡，并显著降低肝脏提取物中胞质 aconitase（一种铁硫蛋白）的活性。在小鼠胚胎成纤维细胞中诱导性敲除 Iop1 会导致胞质 aconitase 的活性降低，但线粒体 aconitase 的活性不受影响，细胞活力丧失。因此，就像在酵母中敲除 Nar1 一样，我们发现敲除小鼠中的 Iop1/Narfl 会导致死亡和胞质铁硫簇组装缺陷。这些发现表明 IOP1 在该途径中起着至关重要的作用。
