Ammonium and nitrate regulate NH4+ uptake activity of Arabidopsis ammonium transporter AtAMT1;3 via phosphorylation at multiple C-terminal sites
© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Experimental Biology.
| Veröffentlicht in: | Journal of experimental botany. - 1985. - 70(2019), 18 vom: 24. Sept., Seite 4919-4930 |
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| 1. Verfasser: | |
| Weitere Verfasser: | , , , , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2019
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| Zugriff auf das übergeordnete Werk: | Journal of experimental botany |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Ammonium transporter (AMT) ammonium uptake membrane transport multisite phosphorylation nitrogen signals phosphorylation post-translational regulation Ammonium Compounds mehr... |
| Zusammenfassung: | © The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Experimental Biology. In plants, nutrient transporters require tight regulation to ensure optimal uptake in complex environments. The activities of many nutrient transporters are post-translationally regulated by reversible phosphorylation, allowing rapid adaptation to variable environmental conditions. Here, we show that the Arabidopsis root epidermis-expressed ammonium transporter AtAMT1;3 was dynamically (de-)phosphorylated at multiple sites in the cytosolic C-terminal region (CTR) responding to ammonium and nitrate signals. Under ammonium resupply rapid phosphorylation of a Thr residue (T464) in the conserved part of the CTR (CTRC) effectively inhibited AtAMT1;3-dependent NH4+ uptake. Moreover, phosphorylation of Thr (T494), one of three phosphorylation sites in the non-conserved part of the CTR (CRTNC), moderately decreased the NH4+ transport activity of AtAMT1;3, as deduced from functional analysis of phospho-mimic mutants in yeast, oocytes, and transgenic Arabidopsis. Double phospho-mutants indicated a role of T494 in fine-tuning the NH4+ transport activity when T464 was non-phosphorylated. Transient dephosphorylation of T494 with nitrate resupply closely paralleled a transient increase in ammonium uptake. These results suggest that T464 phosphorylation at the CTRC acts as a prime switch to prevent excess ammonium influx, while T494 phosphorylation at the CTRNC fine tunes ammonium uptake in response to nitrate. This provides a sophisticated regulatory mechanism for plant ammonium transporters to achieve optimal ammonium uptake in response to various nitrogen forms |
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| Beschreibung: | Date Completed 27.07.2020 Date Revised 27.07.2020 published: Print Citation Status MEDLINE |
| ISSN: | 1460-2431 |
| DOI: | 10.1093/jxb/erz230 |