| Structural highlights
Function
PTR7_ARATH Dual affinity nitrate transporter. Involved in proton-dependent nitrate uptake and in the regulation of the nitrate transporter NRT2.1. Acts also as a nitrate sensor that trigger a specific signaling pathway stimulating lateral root growth and seed germination. The uptake activity is not required for sensor function. Displays an auxin transport facilitation inhibited by high nitrate concentration. Required to prevent auxin accumulation in preemerged lateral root primordia and young lateral roots when external nitrate concentration is low or null. May be involved in the basipetal transport of auxin out of the lateral root tips. Acts as a bidirectional transporter involved in root-to-shoot nitrate translocation.[1] [2] [3] [4] [5] [6] [7] [8] [9]
Publication Abstract from PubMed
Nitrate is a primary nutrient for plant growth, but its levels in soil can fluctuate by several orders of magnitude. Previous studies have identified Arabidopsis NRT1.1 as a dual-affinity nitrate transporter that can take up nitrate over a wide range of concentrations. The mode of action of NRT1.1 is controlled by phosphorylation of a key residue, Thr 101; however, how this post-translational modification switches the transporter between two affinity states remains unclear. Here we report the crystal structure of unphosphorylated NRT1.1, which reveals an unexpected homodimer in the inward-facing conformation. In this low-affinity state, the Thr 101 phosphorylation site is embedded in a pocket immediately adjacent to the dimer interface, linking the phosphorylation status of the transporter to its oligomeric state. Using a cell-based fluorescence resonance energy transfer assay, we show that functional NRT1.1 dimerizes in the cell membrane and that the phosphomimetic mutation of Thr 101 converts the protein into a monophasic high-affinity transporter by structurally decoupling the dimer. Together with analyses of the substrate transport tunnel, our results establish a phosphorylation-controlled dimerization switch that allows NRT1.1 to uptake nitrate with two distinct affinity modes.
Crystal structure of the plant dual-affinity nitrate transporter NRT1.1.,Sun J, Bankston JR, Payandeh J, Hinds TR, Zagotta WN, Zheng N Nature. 2014 Mar 6;507(7490):73-7. doi: 10.1038/nature13074. Epub 2014 Feb 26. PMID:24572362[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Tsay YF, Schroeder JI, Feldmann KA, Crawford NM. The herbicide sensitivity gene CHL1 of Arabidopsis encodes a nitrate-inducible nitrate transporter. Cell. 1993 Mar 12;72(5):705-13. PMID:8453665
- ↑ Wang R, Liu D, Crawford NM. The Arabidopsis CHL1 protein plays a major role in high-affinity nitrate uptake. Proc Natl Acad Sci U S A. 1998 Dec 8;95(25):15134-9. PMID:9844028
- ↑ Liu KH, Tsay YF. Switching between the two action modes of the dual-affinity nitrate transporter CHL1 by phosphorylation. EMBO J. 2003 Mar 3;22(5):1005-13. PMID:12606566 doi:https://dx.doi.org/10.1093/emboj/cdg118
- ↑ Guo FQ, Young J, Crawford NM. The nitrate transporter AtNRT1.1 (CHL1) functions in stomatal opening and contributes to drought susceptibility in Arabidopsis. Plant Cell. 2003 Jan;15(1):107-17. PMID:12509525
- ↑ Munos S, Cazettes C, Fizames C, Gaymard F, Tillard P, Lepetit M, Lejay L, Gojon A. Transcript profiling in the chl1-5 mutant of Arabidopsis reveals a role of the nitrate transporter NRT1.1 in the regulation of another nitrate transporter, NRT2.1. Plant Cell. 2004 Sep;16(9):2433-47. Epub 2004 Aug 19. PMID:15319483 doi:https://dx.doi.org/10.1105/tpc.104.024380
- ↑ Remans T, Nacry P, Pervent M, Filleur S, Diatloff E, Mounier E, Tillard P, Forde BG, Gojon A. The Arabidopsis NRT1.1 transporter participates in the signaling pathway triggering root colonization of nitrate-rich patches. Proc Natl Acad Sci U S A. 2006 Dec 12;103(50):19206-11. Epub 2006 Dec 5. PMID:17148611 doi:https://dx.doi.org/10.1073/pnas.0605275103
- ↑ Ho CH, Lin SH, Hu HC, Tsay YF. CHL1 functions as a nitrate sensor in plants. Cell. 2009 Sep 18;138(6):1184-94. doi: 10.1016/j.cell.2009.07.004. PMID:19766570 doi:https://dx.doi.org/10.1016/j.cell.2009.07.004
- ↑ Wang R, Xing X, Wang Y, Tran A, Crawford NM. A genetic screen for nitrate regulatory mutants captures the nitrate transporter gene NRT1.1. Plant Physiol. 2009 Sep;151(1):472-8. doi: 10.1104/pp.109.140434. Epub 2009 Jul, 24. PMID:19633234 doi:https://dx.doi.org/10.1104/pp.109.140434
- ↑ Krouk G, Lacombe B, Bielach A, Perrine-Walker F, Malinska K, Mounier E, Hoyerova K, Tillard P, Leon S, Ljung K, Zazimalova E, Benkova E, Nacry P, Gojon A. Nitrate-regulated auxin transport by NRT1.1 defines a mechanism for nutrient sensing in plants. Dev Cell. 2010 Jun 15;18(6):927-37. doi: 10.1016/j.devcel.2010.05.008. PMID:20627075 doi:https://dx.doi.org/10.1016/j.devcel.2010.05.008
- ↑ Sun J, Bankston JR, Payandeh J, Hinds TR, Zagotta WN, Zheng N. Crystal structure of the plant dual-affinity nitrate transporter NRT1.1. Nature. 2014 Mar 6;507(7490):73-7. doi: 10.1038/nature13074. Epub 2014 Feb 26. PMID:24572362 doi:https://dx.doi.org/10.1038/nature13074
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