Publication Date:
2014-02-28
Description:
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.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3968801/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3968801/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sun, Ji -- Bankston, John R -- Payandeh, Jian -- Hinds, Thomas R -- Zagotta, William N -- Zheng, Ning -- NS074545/NS/NINDS NIH HHS/ -- R01EY10329/EY/NEI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2014 Mar 6;507(7490):73-7. doi: 10.1038/nature13074. Epub 2014 Feb 26.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Box 357280, University of Washington, Seattle, Washington 98195, USA. ; Department of Physiology and Biophysics, Box 357290, University of Washington, Seattle, Washington 98195, USA. ; 1] Department of Pharmacology, Box 357280, University of Washington, Seattle, Washington 98195, USA [2] Department of Structural Biology, Genentech Inc., South San Francisco, California 94080, USA. ; 1] Department of Pharmacology, Box 357280, University of Washington, Seattle, Washington 98195, USA [2] Howard Hughes Medical Institute, Box 357280, University of Washington, Seattle, Washington 98195, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24572362" target="_blank"〉PubMed〈/a〉
Keywords:
Amino Acid Sequence
;
Anion Transport Proteins/*chemistry/genetics/metabolism
;
Arabidopsis/*chemistry/genetics
;
Binding Sites
;
Biological Transport
;
Cell Membrane/chemistry/metabolism
;
Crystallography, X-Ray
;
Fluorescence Resonance Energy Transfer
;
Models, Biological
;
Models, Molecular
;
Molecular Sequence Data
;
Mutation/genetics
;
Nitrates/chemistry/metabolism
;
Phosphorylation
;
Phosphothreonine/chemistry/metabolism
;
Plant Proteins/*chemistry/genetics/metabolism
;
*Protein Multimerization
;
Protein Structure, Quaternary
;
Protons
;
Structure-Activity Relationship
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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