Control of eukaryotic phosphate homeostasis by inositol polyphosphate sensor domains

Science. 2016 May 20;352(6288):986-90. doi: 10.1126/science.aad9858.

Rebekka Wild ¹, Ruta Gerasimaite ², Ji-Yul Jung ³, Vincent Truffault ⁴, Igor Pavlovic ⁵, Andrea Schmidt ², Adolfo Saiardi ⁶, Henning Jacob Jessen ⁷, Yves Poirier ⁸, Michael Hothorn ⁹, Andreas Mayer ¹⁰

Affiliations

1 Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland.
2 Department of Biochemistry, University of Lausanne, Lausanne, Switzerland.
3 Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland.
4 Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany.
5 Department of Chemistry and Pharmacy, University of Zürich, Zürich, Switzerland.
6 Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK.
7 Department of Chemistry and Pharmacy, University of Zürich, Zürich, Switzerland. Institute of Organic Chemistry, Albert-Ludwigs-University Freiburg, Freiburg, Germany.
8 Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland. yves.poirier@unil.ch michael.hothorn@unige.ch andreas.mayer@unil.ch.
9 Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, Geneva, Switzerland. yves.poirier@unil.ch michael.hothorn@unige.ch andreas.mayer@unil.ch.
10 Department of Biochemistry, University of Lausanne, Lausanne, Switzerland. yves.poirier@unil.ch michael.hothorn@unige.ch andreas.mayer@unil.ch.

PMID: 27080106 DOI: 10.1126/science.aad9858

Abstract

Phosphorus is a macronutrient taken up by cells as inorganic phosphate (P(i)). How cells sense cellular P(i) levels is poorly characterized. Here, we report that SPX domains--which are found in eukaryotic phosphate transporters, signaling proteins, and inorganic polyphosphate polymerases--provide a basic binding surface for inositol polyphosphate signaling molecules (InsPs), the concentrations of which change in response to P(i) availability. Substitutions of critical binding surface residues impair InsP binding in vitro, inorganic polyphosphate synthesis in yeast, and P(i) transport in Arabidopsis In Plants, InsPs trigger the association of SPX proteins with transcription factors to regulate P(i) starvation responses. We propose that InsPs communicate cytosolic P(i) levels to SPX domains and enable them to interact with a multitude of proteins to regulate P(i) uptake, transport, and storage in fungi, Plants, and Animals.

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