Roy Amit, Solodovnikova Natalia, Nicholson Tracy, Antholine William, Walden William E
Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL 60612, USA.
EMBO J. 2003 Sep 15;22(18):4826-35. doi: 10.1093/emboj/cdg455.
Iron regulatory protein 1 (IRP1) is regulated through the assembly/disassembly of a [4Fe-4S] cluster, which interconverts IRP1 with cytosolic aconitase. A genetic screen to isolate Saccharomyces cerevisiae strains bearing mutations in genes required for the conversion of IRP1 to c-aconitase led to the identification of a previously uncharacterized, essential gene, which we call CFD1 (cytosolic Fe-S cluster deficient). CFD1 encodes a highly conserved, putative P-loop ATPase. A non-lethal mutation of CFD1 (cfd1-1) reduced c-aconitase specific activity in IRP1-transformed yeast by >90%, although IRP1 in these cells could be readily converted to c-aconitase in vitro upon incubation with iron alone. IRP1-transformed cfd1-1 yeast lacked EPR-detectable Fe-S clusters in c-aconitase, pointing to a defect in Fe-S cluster assembly. The specific activity of another cytosolic Fe-S protein, Leu1p, was also inhibited by >90% in cfd1-1 yeast, whereas activity of mitochondrial Fe-S proteins was not inhibited. Consistent with a cytosolic site of activity, Cfd1p was localized in the cytoplasm. To our knowledge, Cfd1p is the first cytoplasmic Fe-S cluster assembly factor described in eukaryotes.
铁调节蛋白1（IRP1）通过[4Fe-4S]簇的组装/拆卸来调节，该簇使IRP1与胞质乌头酸酶相互转化。一项基因筛选旨在分离酿酒酵母菌株，这些菌株在将IRP1转化为胞质乌头酸酶所需的基因中带有突变，从而导致鉴定出一个以前未被表征的必需基因，我们将其称为CFD1（胞质铁硫簇缺陷）。CFD1编码一种高度保守的推定P环ATP酶。CFD1的一个非致死突变（cfd1-1）使IRP1转化的酵母中胞质乌头酸酶的比活性降低了90%以上，尽管这些细胞中的IRP1在仅与铁孵育时在体外可以很容易地转化为胞质乌头酸酶。IRP1转化的cfd1-1酵母在胞质乌头酸酶中缺乏EPR可检测的铁硫簇，表明铁硫簇组装存在缺陷。另一种胞质铁硫蛋白Leu1p的比活性在cfd1-1酵母中也被抑制了90%以上，而线粒体铁硫蛋白的活性没有被抑制。与胞质活性位点一致，Cfd1p定位于细胞质中。据我们所知，Cfd1p是真核生物中描述的第一个胞质铁硫簇组装因子。
