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Two bifunctional inositol pyrophosphate kinases/phosphatases control plant phosphate homeostasis

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Zhu Jinsheng, Lau Kelvin, Puschmann Robert, Harmel Robert K, Zhang Youjun, Pries Verena, Gaugler Philipp, Broger Larissa, Dutta Amit K, Jessen Henning J, Schaaf Gabriel, Fernie Alisdair R, Hothorn Ludwig A, Fiedler Dorothea, 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 eLife
Volume (Issue) 8
Page(s) 1 - 25
Title of proceedings eLife
DOI 10.7554/elife.43582

Open Access

URL http://doi.org/10.7554/eLife.43582
Type of Open Access Publisher (Gold Open Access)

Abstract

Many eukaryotic proteins regulating phosphate (Pi) homeostasis contain SPX domains that are receptors for inositol pyrophosphates (PP-InsP), suggesting that PP-InsPs may regulate Pi homeostasis. Here we report that deletion of two diphosphoinositol pentakisphosphate kinases VIH1/2 impairs plant growth and leads to constitutive Pi starvation responses. Deletion of phosphate starvation response transcription factors partially rescues vih1 vih2 mutant phenotypes, placing diphosphoinositol pentakisphosphate kinases in plant Pi signal transduction cascades. VIH1/2 are bifunctional enzymes able to generate and break-down PP-InsPs. Mutations in the kinase active site lead to increased Pi levels and constitutive Pi starvation responses. ATP levels change significantly in different Pi growth conditions. ATP-Mg2+ concentrations shift the relative kinase and phosphatase activities of diphosphoinositol pentakisphosphate kinases in vitro. Pi inhibits the phosphatase activity of the enzyme. Thus, VIH1 and VIH2 relay changes in cellular ATP and Pi concentrations to changes in PP-InsP levels, allowing plants to maintain sufficient Pi levels.
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