A type 2C protein phosphatase activates high-affinity nitrate uptake by dephosphorylating NRT2.1

Yuri Ohkubo, Keiko Kuwata & Yoshikatsu Matsubayashi

Nature Plants volume 7, pages 310–316 (2021)/ Published: 08 March 2021

The nitrate transporter NRT2.1, which plays a central role in high-affinity nitrate uptake in roots, is activated at the post-translational level in response to nitrogen (N) starvation1^,2. However, the critical enzymes required for the post-translational activation of NRT2.1 remain to be identified. Here, we show that a type 2C protein phosphatase, designated CEPD-induced phosphatase (CEPH), activates high-affinity nitrate uptake by directly dephosphorylating Ser501 of NRT2.1, a residue that functions as a negative phospho-switch in Arabidopsis2. CEPH is predominantly expressed in epidermal and cortex cells in roots and is upregulated by N starvation via a CEPDL2/CEPD1/2-mediated long-distance signalling from shoots3^,4. The loss of CEPH leads to marked decreases in high-affinity nitrate uptake, tissue nitrate content and plant biomass. Collectively, our results identify CEPH as a crucial enzyme in the N-starvation-dependent activation of NRT2.1 and provide molecular and mechanistic insights into how plants regulate high-affinity nitrate uptake at the post-translational level in response to the N environment.

See: https://www.nature.com/articles/s41477-021-00870-9

Figure: The blue regions contain the protein CEPH, which activates the nitrate transporter protein NRT2.1 in response to nitrogen deficiency. Photo Source: Nagoya University