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Inositol pyrophosphates promote the interaction of SPX domains with the coiled-coil motif of PHR transcription factors to regulate plant phosphate homeostasis

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Ried Martina K., Wild Rebekka, Zhu Jinsheng, Pipercevic Joka, Sturm Kristina, Broger Larissa, Harmel Robert K., Abriata Luciano A., Hothorn Ludwig A., Fiedler Dorothea, Hiller Sebastian, Hothorn Michael,
Project Discovery and mechanistic dissection of novel signaling pathways controlling phosphate homeostasis in eukaryotes
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Original article (peer-reviewed)

Journal Nature Communications
Volume (Issue) 12(1)
Page(s) 384 - 384
Title of proceedings Nature Communications
DOI 10.1038/s41467-020-20681-4

Open Access

Type of Open Access Publisher (Gold Open Access)


Abstract Phosphorus is an essential nutrient taken up by organisms in the form of inorganic phosphate (Pi). Eukaryotes have evolved sophisticated Pi sensing and signaling cascades, enabling them to stably maintain cellular Pi concentrations. Pi homeostasis is regulated by inositol pyrophosphate signaling molecules (PP-InsPs), which are sensed by SPX domain-containing proteins. In plants, PP-InsP-bound SPX receptors inactivate Myb coiled-coil (MYB-CC) Pi starvation response transcription factors (PHRs) by an unknown mechanism. Here we report that a InsP 8 –SPX complex targets the plant-unique CC domain of PHRs. Crystal structures of the CC domain reveal an unusual four-stranded anti-parallel arrangement. Interface mutations in the CC domain yield monomeric PHR1, which is no longer able to bind DNA with high affinity. Mutation of conserved basic residues located at the surface of the CC domain disrupt interaction with the SPX receptor in vitro and in planta, resulting in constitutive Pi starvation responses. Together, our findings suggest that InsP 8 regulates plant Pi homeostasis by controlling the oligomeric state and hence the promoter binding capability of PHRs via their SPX receptors.