Multi-domain CGFS-type glutaredoxin Grx4 regulates iron homeostasis via direct interaction with a repressor Fep1 in fission yeast |
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Authors: | Kim Kyoung-Dong Kim Hyo-Jin Lee Kyung-Chang Roe Jung-Hye |
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Affiliation: | Laboratory of Molecular Microbiology, School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea |
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Abstract: | 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. |
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Keywords: | Monothiol glutaredoxin Fep1 Iron homeostasis Fission yeast CGFS motif |
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