The intracellular inositol (pyro)phosphate receptor AtSPX1 reciprocally binds to P1BS DNA

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Whitfield, Hayley L., Gilmartin, Megan, Riley, Andrew M., Shipton, Megan L., Potter, Barry V. L., Hemmings, Andrew M and Brearley, Charles A. (2026) The intracellular inositol (pyro)phosphate receptor AtSPX1 reciprocally binds to P1BS DNA. Nature Communications. ISSN 2041-1723

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Abstract

The response of plants to phosphate starvation engages PHR (CC-MYB-PHOSPHATE STARVATION RESPONSE) transcription factors that bind to P1BS (GNATATNC) promoter elements of phosphate-starvation induced (PSI) genes. The encoded proteins include single-domain SPX (SYG1/Pho81/XPR1) proteins. SPX proteins bind PHR proteins. Current models of SPX1: PHR interaction define only a high-phosphate role for SPX1, as an inositol (pyro)phosphate-dependent negative regulator of PHR. Here, by combination of chemical synthesis, orthogonal binding assays and molecular modeling we report that full-length SPX1 binds P1BS promoter elements and inositol (pyro)phosphates with similar affinity. Inositol (pyro)phosphates and DNA are reciprocally competing ligands of SPX1. Structural models of SPX1: inositol (pyrophosphate) and of SPX1: P1BS interaction are provided beside a working hypothesis of SPX1: PHR1 interaction. The results reveal the low-phosphate function of SPX1. These findings proffer a fundamentally different perspective of SPX involvement in the phosphate starvation response (PSR).

Item Type: Article
Uncontrolled Keywords: abiotic,plant physiology,proteins
Faculty \ School: Faculty of Science > School of Biological Sciences
UEA Research Groups: Faculty of Science > Research Groups > Plant Sciences
Faculty of Science > Research Groups > Molecular Microbiology
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Depositing User: LivePure Connector
Date Deposited: 09 Mar 2026 16:31
Last Modified: 15 Mar 2026 06:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/102276
DOI: 10.1038/s41467-026-69810-5

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