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A type 2C protein phosphatase activates high-affinity nitrate uptake by dephosphorylating NRT2.1
Yuri Ohkubo1, Keiko Kuwata2, Yoshikatsu Matsubayashi3
1Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan.
Nature Plants
|March 9, 2021
Summary
A novel protein phosphatase, CEPH, activates nitrate transporter NRT2.1 in plants during nitrogen starvation. This discovery reveals a key mechanism for regulating plant nutrient uptake and growth.
Area of Science:
- Plant Biology
- Molecular Plant Physiology
- Nutrient Signaling
Background:
- High-affinity nitrate uptake in plant roots is crucial for growth and is regulated by the NRT2.1 transporter.
- NRT2.1 activity is modulated post-translationally, but the enzymes involved remain unidentified.
- Nitrogen (N) starvation triggers adaptive responses in plants, including changes in nitrate uptake.
Purpose of the Study:
- To identify the enzyme responsible for the post-translational activation of the nitrate transporter NRT2.1.
- To elucidate the molecular mechanism by which NRT2.1 is activated under nitrogen-deficient conditions.
- To understand the role of this activation in plant adaptation to nitrogen starvation.
Main Methods:
- Biochemical assays to identify protein phosphatase activity.
- Site-directed mutagenesis to analyze the role of specific phosphorylation sites on NRT2.1.
- Analysis of gene expression and protein localization in Arabidopsis thaliana under varying nitrogen conditions.
- Phenotypic analysis of knockout mutants for the identified phosphatase.
Main Results:
- A type 2C protein phosphatase, CEPH, was identified as a key activator of NRT2.1.
- CEPH directly dephosphorylates Ser501 on NRT2.1, relieving its inhibition.
- CEPH expression is induced by N starvation via long-distance signaling and is essential for high-affinity nitrate uptake, nitrate content, and plant biomass.
Conclusions:
- CEPH is a critical enzyme for NRT2.1 activation during nitrogen starvation.
- Dephosphorylation of NRT2.1 by CEPH is a key post-translational regulatory mechanism for nitrate uptake.
- This finding provides insights into plant adaptation to nutrient availability and its impact on growth.
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