Nakai Y, Nakai M, Hayashi H, Kagamiyama H
Department of Biochemistry, Osaka Medical College, Takatsuki, Osaka 569-8686 Japan.
J Biol Chem. 2001 Mar 16;276(11):8314-20. doi: 10.1074/jbc.M007878200. Epub 2000 Dec 7.
Saccharomyces cerevisiae Nfs1p is mainly found in the mitochondrial matrix and has been shown to participate in iron-sulfur cluster assembly. We show here that Nfs1p contains a potential nuclear localization signal, RRRPR, in its mature part. When this sequence was mutated to RRGSR, the mutant protein could not restore cell growth under chromosomal NFS1-depleted conditions. However, this mutation did not affect the function of Nfs1p in biogenesis of mitochondrial iron-sulfur proteins. The growth defect of the mutant was complemented by simultaneous expression of the mature Nfs1p, which contains the intact nuclear localization signal but lacks its mitochondrial-targeting presequence. These results suggest that a fraction of Nfs1p is localized in the nucleus and is essential for cell viability.
酿酒酵母Nfs1p主要存在于线粒体基质中，并且已被证明参与铁硫簇的组装。我们在此表明，Nfs1p在其成熟部分含有一个潜在的核定位信号RRRPR。当该序列突变为RRGSR时，突变蛋白在染色体NFS1缺失的条件下无法恢复细胞生长。然而，这种突变并不影响Nfs1p在线粒体铁硫蛋白生物合成中的功能。成熟的Nfs1p（其含有完整的核定位信号但缺乏线粒体靶向前序列）的同时表达弥补了突变体的生长缺陷。这些结果表明，一部分Nfs1p定位于细胞核中，并且对细胞活力至关重要。
