Home
Resources
Publications
Ammonium and Nitrate Regulate NH4+ Uptake Activity of Arabidopsis Ammonium Transporter AtAMT1;3 via Phosphorylation at Multiple C-terminal Sites

Ammonium and Nitrate Regulate NH4+ Uptake Activity of Arabidopsis Ammonium Transporter AtAMT1;3 via Phosphorylation at Multiple C-terminal Sites

Xiangyu Wu, Ting Liu, Yongjian Zhang, Fengying Duan, Benjamin Neuhäuser, Uwe Ludewig, Waltraud X Schulze, Lixing Yuan

J Exp Bot. 2019 Sep 24;70(18):4919-4930.

PMID: 31087098

Abstract:

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.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP16919247	Ammonium hexafluorostannate		16919-24-7	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: