%0 Generic %A Wang, Liguang %A Feng, Xueying %A Zhao, Hong %A Wang, Lidong %A An, Lizhe %A Qiu, Quan-Sheng %D 2014 %T Functional Analysis of the Na+,K+/H+ Antiporter PeNHX3 from the Tree Halophyte Populus euphratica in Yeast by Model-Guided Mutagenesis %U https://plos.figshare.com/articles/dataset/Functional_Analysis_of_the_Na_K_H_Antiporter_PeNHX3_from_the_Tree_Halophyte_Populus_euphratica_in_Yeast_by_Model_Guided_Mutagenesis/1130114 %R 10.1371/journal.pone.0104147 %2 https://ndownloader.figshare.com/files/1624515 %2 https://ndownloader.figshare.com/files/1624516 %K Biochemistry %K proteins %K protein structure %K Protein structure prediction %K Transmembrane transport proteins %K biophysics %K Ion transport %K cell biology %K Cellular structures and organelles %K Cell membranes %K Membrane proteins %K Transmembrane proteins %K genetics %K Gene types %K Mutant genes %K mutation %K molecular biology %K Molecular biology techniques %K organisms %K plants %K brassica %K Arabidopsis thaliana %K Plant science %K Plant physiology %K Solute transport %K antiporter %K penhx3 %K halophyte %K yeast %K model-guided %K mutagenesis %X

Na+,K+/H+ antiporters are H+-coupled cotransporters that are crucial for cellular homeostasis. Populus euphratica, a well-known tree halophyte, contains six Na+/H+ antiporter genes (PeNHX1-6) that have been shown to function in salt tolerance. However, the catalytic mechanisms governing their ion transport remain largely unknown. Using the crystal structure of the Na+/H+ antiporter from the Escherichia coli (EcNhaA) as a template, we built the three-dimensional structure of PeNHX3 from P. euphratica. The PeNHX3 model displays the typical TM4-TM11 assembly that is critical for ion binding and translocation. The PeNHX3 structure follows the ‘positive-inside’ rule and exhibits a typical physicochemical property of the transporter proteins. Four conserved residues, including Tyr149, Asn187, Asp188, and Arg356, are indentified in the TM4-TM11 assembly region of PeNHX3. Mutagenesis analysis showed that these reserved residues were essential for the function of PeNHX3: Asn187 and Asp188 (forming a ND motif) controlled ion binding and translocation, and Tyr149 and Arg356 compensated helix dipoles in the TM4-TM11 assembly. PeNHX3 mediated Na+, K+ and Li+ transport in a yeast growth assay. Domain-switch analysis shows that TM11 is crucial to Li+ transport. The novel features of PeNHX3 in ion binding and translocation are discussed.

%I PLOS ONE