Published October 30, 2025
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NUDIX hydrolases target specific inositol pyrophosphates and regulate phosphate homeostasis and bacterial pathogen susceptibility in Arabidopsis.

Creators

  • 1. Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, University of Bonn, Bonn, 53115, Germany.
  • 2. University of Bonn
  • 3. Department of Chemistry and Pharmacy and CIBSS-Centre for Integrative Biological Signalling Studies, Albert-Ludwigs University Freiburg, Freiburg, 79104, Germany.
  • 4. Protein Mass Spectronomy, Max Planck Institute for Plant Breeding Research, Cologne, 50829, Germany.
  • 5. Department of General Genetics, Center of Plant Molecular Biology (ZMBP) University of Tübingen, Tübingen, 72076, Germany.
  • 6. University of Tübingen
  • 7. Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, 13125, Germany.
  • 8. Humboldt-Universität zu Berlin, Institut für Chemie, Berlin, 12489, Germany.
  • 9. Humboldt University of Berlin
  • 10. UNESCO-Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, 121001, Haryana, India.
  • 11. Molecular Phytomedicine, Institute of Crop Science and Resource Conservation, University of Bonn, Bonn, 53115, Germany.
  • 12. Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, Halle (Saale), 06120, Germany.
  • 13. Department of Crop Bioinformatics, Institute of Crop Science and Resource Conservation, University of Bonn, Bonn, 53115, Germany.
  • 14. Department of Physiology & Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, 06466, Germany.

Description

Inositol pyrophosphates (PP-InsPs) are important signaling molecules that regulate diverse cellular processes in eukaryotes, including energy homeostasis, phosphate (Pi) signaling, and phytohormone perception. Yet, in plants, the enzymes responsible for their turnover remain largely unknown. Using a non-hydrolysable PP-InsP analog in a pull-down approach, we identified a family of Arabidopsis NUDIX-type hydrolases (NUDTs) that group into two closely related subclades. Through in vitro assays, heterologous expression systems, and higher order gene-edited mutants, we explored the substrate specificities and physiological roles of these hydrolases. Using a combination of strong anion exchange high-performance liquid chromatography (SAX-HPLC), polyacrylamide gel electrophoresis (PAGE), and capillary electrophoresis electrospray ionization mass spectrometry (CE-ESI-MS), we found that their PP-InsP pyrophosphatase activity is enantiomer selective and Mg2+ dependent. Specifically, Subclade I NUDTs preferentially hydrolyze 4-InsP7, while Subclade II NUDTs target 3-InsP7, with minor activity against other PP-InsPs, including 5-InsP7. In higher order mutants of Subclade II NUDTs, we observed defects in both Pi and iron homeostasis, accompanied by increased levels of 1/3-InsP7 and 5-InsP7, with a markedly larger increase in 1/3-InsP7. Ectopic expression of NUDTs from both subclades induced local Pi starvation responses (PSRs), while RNA-seq analysis comparing wild-type (WT) and Subclade II nudt12/13/16 loss-of-function plants indicates additional PSR-independent roles, potentially involving 1/3-InsP7 in the regulation of plant defense. Consistently, nudt12/13/16 mutants displayed enhanced resistance to Pseudomonas syringae infection, indicating a role in bacterial pathogen susceptibility. Expanding beyond Subclade II NUDTs, we demonstrated susceptibility of the 3PP-position of PP-InsPs to enzymatic activities unrelated to NUDTs, and found that such activities are conserved across plants and humans. Additionally, we observed that NUDT effectors from pathogenic ascomycete fungi exhibit a substrate specificity similar to Subclade I NUDTs. Collectively, our findings reveal new roles for NUDTs in PP-InsP signaling, plant nutrient and immune responses, and highlight a cross-kingdom conservation of PP-InsP-metabolizing enzymes.
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