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Nature. 2014 Mar 6;507(7490):68-72. doi: 10.1038/nature13116. Epub 2014 Feb 26.

Molecular basis of nitrate uptake by the plant nitrate transporter NRT1.1.

Author information

1
Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
2
1] Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK [2] Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0FA, UK.

Abstract

The NRT1/PTR family of proton-coupled transporters are responsible for nitrogen assimilation in eukaryotes and bacteria through the uptake of peptides. However, in most plant species members of this family have evolved to transport nitrate as well as additional secondary metabolites and hormones. In response to falling nitrate levels, NRT1.1 is phosphorylated on an intracellular threonine that switches the transporter from a low-affinity to high-affinity state. Here we present both the apo and nitrate-bound crystal structures of Arabidopsis thaliana NRT1.1, which together with in vitro binding and transport data identify a key role for His 356 in nitrate binding. Our data support a model whereby phosphorylation increases structural flexibility and in turn the rate of transport. Comparison with peptide transporters further reveals how the NRT1/PTR family has evolved to recognize diverse nitrogenous ligands, while maintaining elements of a conserved coupling mechanism within this superfamily of nutrient transporters.

PMID:
24572366
PMCID:
PMC3982047
DOI:
10.1038/nature13116
[Indexed for MEDLINE]
Free PMC Article

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