Laboratory of Molecular Microbiology, School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul, Republic of Korea.
Biochem Biophys Res Commun. 2011 May 20;408(4):609-14. doi: 10.1016/j.bbrc.2011.04.069. Epub 2011 Apr 22.
The fission yeast Schizosaccharomyces pombe contains two CGFS-type monothiol glutaredoxins, Grx4 and Grx5, which are localized primarily in the nucleus and mitochondria, respectively. We observed involvement of Grx4 in regulating iron-responsive gene expression, which is modulated by a repressor Fep1. Lack of Grx4 caused defects not only in growth but also in the expression of both iron-uptake and iron-utilizing genes regardless of iron availability. In order to unravel how Grx4 is involved in Fep1-mediated regulation, interaction between them was investigated. Co-immunoprecipitation and bimolecular fluorescence complementation (BiFC) revealed that Grx4 physically interacts with Fep1 in vivo. BiFC revealed localized nuclear dots produced by interaction of Grx4 with Fep1. Mutation of cysteine-172 in the CGFS motif to serine (C172S) produced effects similarly observed under Grx4 depletion, such as the loss of iron-dependent gene regulation and the absence of nuclear dots in BiFC analysis. These results suggest that the ability of Grx4 to bind iron, most likely Fe-S cofactor, could be critical in interacting with and modulating the activity of Fep1.
裂殖酵母 Schizosaccharomyces pombe 含有两种 CGFS 型单硫谷胱甘肽还原酶，Grx4 和 Grx5，它们分别主要定位于细胞核和线粒体。我们观察到 Grx4 参与调节铁反应基因的表达，该表达受抑制因子 Fep1 调控。缺乏 Grx4 不仅会导致生长缺陷，还会导致铁摄取和利用基因的表达缺陷，而与铁的可用性无关。为了揭示 Grx4 如何参与 Fep1 介导的调节，研究了它们之间的相互作用。共免疫沉淀和双分子荧光互补（BiFC）显示 Grx4 与 Fep1 在体内物理相互作用。BiFC 显示 Grx4 与 Fep1 相互作用产生的核点局部化。CGFS 基序中半胱氨酸 172 突变为丝氨酸（C172S）产生的效果类似于 Grx4 耗竭时观察到的效果，例如铁依赖性基因调节的丧失和 BiFC 分析中核点的缺失。这些结果表明，Grx4 结合铁（很可能是 Fe-S 辅助因子）的能力对于与 Fep1 相互作用和调节其活性可能至关重要。
