OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 148/2/796    most recent pp.108.124248v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Zhao, J. Articles by Hirschi, K. D. Search for Related Content PubMed PubMed Citation Articles by Zhao, J. Articles by Hirschi, K. D. Agricola Articles by Zhao, J. Articles by Hirschi, K. D.

BIOENERGETICS AND PHOTOSYNTHESIS

AtCHX13 Is a Plasma Membrane K⁺ Transporter^{1,[C],[W],[OA]}

United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030 (J.Z., N.-H.C., M.M., N.G., K.D.H.); Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (C.M.M., E.B.B.); Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (S.P., H.S.); Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108 (J.M.W.); and Vegetable and Fruit Improvement Center, Texas A&M University, College Station, Texas 77845 (K.D.H.)

Potassium (K⁺) homeostasis is essential for diverse cellular processes, although how various cation transporters collaborate to maintain a suitable K⁺ required for growth and development is poorly understood. The Arabidopsis (Arabidopsis thaliana) genome contains numerous cation:proton antiporters (CHX), which may mediate K⁺ transport; however, the vast majority of these transporters remain uncharacterized. Here, we show that AtCHX13 (At2g30240) has a role in K⁺ acquisition. AtCHX13 suppressed the sensitivity of yeast (Saccharomyces cerevisiae) mutant cells defective in K⁺ uptake. Uptake experiments using ⁸⁶Rb⁺ as a tracer for K⁺ demonstrated that AtCHX13 mediated high-affinity K⁺ uptake in yeast and in plant cells with a K_m of 136 and 196 µM, respectively. Functional green fluorescent protein-tagged versions localized to the plasma membrane of both yeast and plant. Seedlings of null chx13 mutants were sensitive to K⁺ deficiency conditions, whereas overexpression of AtCHX13 reduced the sensitivity to K⁺ deficiency. Collectively, these results suggest that AtCHX13 mediates relatively high-affinity K⁺ uptake, although the mode of transport is unclear at present. AtCHX13 expression is induced in roots during K⁺-deficient conditions. These results indicate that one role of AtCHX13 is to promote K⁺ uptake into plants when K⁺ is limiting in the environment.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Kendal D. Hirschi (kendalh{at}bcm.tmc.edu).

^[C] Some figures in this article are displayed in color online but in black and white in the print edition.

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.108.124248

^* Corresponding author; e-mail kendalh{at}bcm.tmc.edu.

Received June 9, 2008; accepted July 29, 2008; published August 1, 2008.

This article has been cited by other articles:

				Y. Sawaki, S. Iuchi, Y. Kobayashi, Y. Kobayashi, T. Ikka, N. Sakurai, M. Fujita, K. Shinozaki, D. Shibata, M. Kobayashi, et al. STOP1 Regulates Multiple Genes That Protect Arabidopsis from Proton and Aluminum Toxicities Plant Physiology, May 1, 2009; 150(1): 281 - 294. [Abstract] [Full Text] [PDF]