AtCHX13 is a plasma membrane K+ transporter

Jian Zhao, Ning Hui Cheng, Christy M. Motes, Elison B. Blancaflor, Miranda Moore, Naomi Gonzales, Senthilkumar Padmanaban, Heven Sze, John M. Ward, Kendal D. Hirschi

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

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 Km 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.

Original languageEnglish (US)
Pages (from-to)796-807
Number of pages12
JournalPlant physiology
Volume148
Issue number2
DOIs
StatePublished - Oct 2008

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