Loading…
The Arabidopsis Na+/H+Exchanger AtNHX1 Catalyzes Low Affinity Na+ and K+ Transport in Reconstituted Liposomes
In saline environments, plants accumulate Na+ in vacuoles through the activity of tonoplast Na+/H+ antiporters. The first gene for a putative plant vacuolar Na+/H+ antiporter,AtNHX1, was isolated from Arabidopsis and shown to increase plant tolerance to NaCl. However, AtNHX1mRNA was up-regulated by...
Saved in:
Published in: | The Journal of biological chemistry 2002-01, Vol.277 (4), p.2413-2418 |
---|---|
Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | In saline environments, plants accumulate Na+ in vacuoles through the activity of tonoplast Na+/H+ antiporters. The first gene for a putative plant vacuolar Na+/H+ antiporter,AtNHX1, was isolated from Arabidopsis and shown to increase plant tolerance to NaCl. However, AtNHX1mRNA was up-regulated by Na+ or K+ salts in plants and substituted for the homologous protein of yeast to restore tolerance to several toxic cations. To study the ion selectivity of the AtNHX1 protein, we have purified a histidine-tagged version of the protein from yeast microsomes by Ni2+ affinity chromatography, reconstituted the protein into lipid vesicles, and measured cation-dependent H+ exchange with the fluorescent pH indicator pyranine. The protein catalyzed Na+ and K+ transport with similar affinity in the presence of a pH gradient. Li+ and Cs+ ions were also transported with lower affinity. Ion exchange by AtNHX1 was inhibited 70% by the amiloride analog ethylisopropyl-amiloride. Our data indicate a role for intracellular antiporters in organelle pH control and osmoregulation. |
---|---|
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M105043200 |