RT Journal Article SR Electronic T1 NRT2.1 phosphorylation prevents root high affinity nitrate uptake activity in Arabidopsis thaliana JF bioRxiv FD Cold Spring Harbor Laboratory SP 583542 DO 10.1101/583542 A1 Aurore Jacquot A1 Valentin Chaput A1 Adeline Mauries A1 Zhi Li A1 Pascal Tillard A1 Cécile Fizames A1 Pauline Bonillo A1 Fanny Bellegarde A1 Edith Laugier A1 Véronique Santoni A1 Sonia Hem A1 Antoine Martin A1 Alain Gojon A1 Waltraud Schulze A1 Laurence Lejay YR 2019 UL http://biorxiv.org/content/early/2019/03/20/583542.abstract AB In Arabidopsis thaliana, NRT2.1 codes for a main component of the root nitrate high-affinity transport system. Previous studies revealed that post-translational regulation of NRT2.1 plays an important role in the control of root nitrate uptake and that one mechanism could correspond to NRT2.1 C-terminus processing. To further investigate this hypothesis, we produced transgenic plants with truncated forms of NRT2.1. It revealed an essential sequence for NRT2.1 activity, located between the residues 494-513. Using a phospho-proteomic approach, we found that this sequence contains one phosphorylation site, at serine 501, which can inactivate NRT2.1 function when mimicking the constitutive phosphorylation of this residue in transgenic plants. This phenotype could neither be explained by changes in abundance of NRT2.1 and NAR2.1, a partner protein of NRT2.1, nor by a lack of interaction between these two proteins. Finally, the relative level of serine 501 phosphorylation was found to be modulated by nitrate in wildtype plants. Altogether, these observations allowed us to propose a model for a new and essential mechanism for the regulation of NRT2.1 activity.