Dataset Information

Schizosaccharomyces pombe Grx4 regulates the transcriptional repressor Php4 via [2Fe-2S] cluster binding.

ABSTRACT: The fission yeast Schizosaccharomyces pombe expresses the CCAAT-binding factor Php4 in response to iron deprivation. Php4 forms a transcription complex with Php2, Php3, and Php5 to repress the expression of iron proteins as a means to economize iron usage. Previous in vivo results demonstrate that the function and location of Php4 are regulated in an iron-dependent manner by the cytosolic CGFS type glutaredoxin Grx4. In this study, we aimed to biochemically define these protein-protein and protein-metal interactions. Grx4 was found to bind a [2Fe-2S] cluster with spectroscopic features similar to other CGFS glutaredoxins. Grx4 and Php4 also copurify as a complex with a [2Fe-2S] cluster that is spectroscopically distinct from the cluster on Grx4 alone. In vitro titration experiments suggest that these Fe-S complexes may not be interconvertible in the absence of additional factors. Furthermore, conserved cysteines in Grx4 (Cys172) and Php4 (Cys221 and Cys227) are necessary for Fe-S cluster binding and stable complex formation. Together, these results show that Grx4 controls Php4 function through binding of a bridging [2Fe-2S] cluster.

SUBMITTER: Dlouhy AC

PROVIDER: S-EPMC5595146 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Schizosaccharomyces pombe Grx4 regulates the transcriptional repressor Php4 via [2Fe-2S] cluster binding.

Dlouhy Adrienne C AC Beaudoin Jude J Labbé Simon S Outten Caryn E CE

Metallomics : integrated biometal science 20170801 8

The fission yeast Schizosaccharomyces pombe expresses the CCAAT-binding factor Php4 in response to iron deprivation. Php4 forms a transcription complex with Php2, Php3, and Php5 to repress the expression of iron proteins as a means to economize iron usage. Previous in vivo results demonstrate that the function and location of Php4 are regulated in an iron-dependent manner by the cytosolic CGFS type glutaredoxin Grx4. In this study, we aimed to biochemically define these protein-protein and prote ...[more]

PMID: 28725905

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Project description:Due to iron's essential role in cellular metabolism, most organisms must maintain their homeostasis. In this regard, the fission yeast Schizosaccharomyces pombe (sp) uses two transcription factors to regulate intracellular iron levels: spFep1 under iron-rich conditions and spPhp4 under iron-deficient conditions, which are controlled by spGrx4. However, bioinformatics analysis to understand the role of the spGrx4/spFep1/spPhp4 axis in maintaining iron homeostasis in S. pombe is still lacking. Our study aimed to perform bioinformatics analysis on S. pombe proteins and their sequence homologs in Aspergillus flavus (af), Saccharomyces cerevisiae (sc), and Homo sapiens (hs) to understand the role of spGrx4, spFep1, and spPhp4 in maintaining iron homeostasis. The three genes' expression patterns were also examined at various iron concentrations. A multiple sequence alignment analysis of spGrx4 and its sequence homologs revealed a conserved cysteine residue in each PF00085 domain. Blast results showed that hsGLRX3 is most similar to spGrx4. In addition, spFep1 is most closely related in sequence to scDal80, whereas scHap4 is most similar to spFep1. We also found two highly conserved motifs in spFep1 and its sequence homologs that are significant for iron transport systems because they contain residues involved in iron homeostasis. The scHap4 is most similar to spPhp4. Using STRING to analyze protein-protein interactions, we found that spGrx4 interacts strongly with spPhp4 and spFep1. Furthermore, spGrx4, spPhp4, and spFep1 interact with spPhp2, spPhp3, and spPhp5, indicating that the three proteins play cooperative roles in iron homeostasis. At the highest level of Fe, spgrx4 had the highest expression, followed by spfep1, while spphp4 had the lowest expression; a contrast occurred at the lowest level of Fe, where spgrx4 expression remained constant. Our findings support the notion that organisms develop diverse strategies to maintain iron homeostasis.

Dataset Information

Schizosaccharomyces pombe Grx4 regulates the transcriptional repressor Php4 via [2Fe-2S] cluster binding.

Publications

Schizosaccharomyces pombe Grx4 regulates the transcriptional repressor Php4 via [2Fe-2S] cluster binding.

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