Riemer, E;
Qiu, D;
Laha, D;
Harmel, RK;
Gaugler, P;
Gaugler, V;
Frei, M;
... Giehl, RFH; + view all
(2021)
ITPK1 is an InsP6/ADP phosphotransferase that controls phosphate signaling in Arabidopsis.
Molecular Plant
10.1016/j.molp.2021.07.011.
(In press).
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Abstract
In plants, phosphate (Pi) homeostasis is regulated by the interaction of PHR transcription factors with stand-alone SPX proteins, which act as sensors for inositol pyrophosphates. Here, we combined different methods to obtain a comprehensive picture of how inositol (pyro)phosphate metabolism is regulated by Pi and dependent on the inositol phosphate kinase ITPK1. We found that inositol pyrophosphates are more responsive to Pi than lower inositol phosphates, a response conserved across kingdoms. With CE-ESI-MS we could separate different InsP7 isomers in Arabidopsis and rice, and identify 4/6-InsP7 and a PP-InsP4 isomer hitherto not reported in plants. We found that the inositol pyrophosphates 1/3-InsP7, 5-InsP7 and InsP8 increase severalfold in shoots after Pi resupply and that tissue-specific accumulation of inositol pyrophosphates relies on ITPK1 activities and MRP5-dependent InsP6 compartmentalization. Notably, ITPK1 is critical for Pi-dependent 5-InsP7 and InsP8 synthesis in planta and its activity regulates Pi starvation responses in a PHR-dependent manner. Furthermore, we demonstrate that ITPK1-mediated conversion of InsP6 to 5-InsP7 requires high ATP concentrations and that Arabidopsis ITPK1 has an ADP phosphotransferase activity to dephosphorylate specifically 5-InsP7 under low ATP. Collectively, our study provides deeper insights into Pi-dependent changes in nutritional and energetic states with the synthesis of regulatory inositol pyrophosphates.
| Type: | Article |
|---|---|
| Title: | ITPK1 is an InsP6/ADP phosphotransferase that controls phosphate signaling in Arabidopsis |
| Location: | England |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.molp.2021.07.011 |
| Publisher version: | http://dx.doi.org/10.1016/j.molp.2021.07.011 |
| Language: | English |
| Additional information: | © The Author 2021. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). |
| Keywords: | diphosphoinositol pentakisphosphate kinase, inositol 1,3,4-trisphosphate 5/6-kinase 1, inositol phosphates, inositol pyrophosphates, phosphate homeostasis, phosphate signaling |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Lab for Molecular Cell Bio MRC-UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10134489 |
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