The Asp1 pyrophosphatase from S. pombe hosts a [2Fe-2S]2+ cluster in vivo

The Schizosaccharomyces pombe Asp1 protein is a bifunctional kinase/pyrophosphatase that belongs to the highly conserved eukaryotic diphosphoinositol pentakisphosphate kinase PPIP5K/Vip1 family. The N-terminal Asp1 kinase domain generates specific high-energy inositol pyrophosphate (IPP) molecules, which are hydrolyzed by the C-terminal Asp1 pyrophosphatase domain (Asp1(365-920)). Thus, Asp1 activities regulate the intracellular level of a specific class of IPP molecules, which control a wide number of biological processes ranging from cell morphogenesis to chromosome transmission. Recently, it was shown that chemical reconstitution of Asp1(371-920) leads to the formation of a [2Fe-2S] cluster; however, the biological relevance of the cofactor remained under debate. In this study, we provide evidence for the presence of the Fe-S cluster in Asp1(365-920) inside the cell. However, we show that the Fe-S cluster does not influence Asp1 pyrophosphatase activity in vitro or in vivo. Characterization of the as-isolated protein by electronic absorption spectroscopy, mass spectrometry, and X-ray absorption spectroscopy is consistent with the presence of a [2Fe-2S](2+) cluster in the enzyme. Furthermore, we have identified the cysteine ligands of the cluster. Overall, our work reveals that Asp1 contains an Fe-S cluster in vivo that is not involved in its pyrophosphatase activity.

Automated summary

The Asp1 protein is a bifunctional kinase/pyrophosphatase, containing an Fe-S cluster in vivo that does not influence its pyrophosphatase activity.