AtNHX8, a member of the monovalent cation:proton antiporter-1 family in Arabidopsis thaliana, encodes a putative Li+/H+ antiporter

Rui An, Qi Jun Chen, Mao Feng Chai, Ping Li Lu, Zhao Su, Zhi Xiang Qin, Jia Chen, Xue Chen Wang

Research output: Contribution to journalArticle

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Abstract

The Arabidopsis monovalent cation:proton antiporter-1 (CPA1) family includes eight members, AtNHX1-8. AtNHX1 and AtNHX7/SOS1 have been well characterized as tonoplast and plasma membrane Na+/H+ antiporters, respectively. The proteins AtNHX2-6 have been phylogenetically linked to AtNHX1, while AtNHX8 appears to be related to AtNHX7/SOS1. Here we report functional characterization of AtNHX8. AtNHX8 T-DNA insertion mutants are hypersensitive to lithium ions (Li+) relative to wild-type plants, but not to the other metal ions such as sodium (Na+), potassium (K+) and caesium (Cs+). AtNHX8 overexpression in a triple-deletion yeast mutant AXT3 that exhibits defective Na+/Li + transport specifically suppresses sensitivity to Li+, but does not affect Na+ sensitivity. Likewise, AtNHX8 overexpression complemented sensitivity to Li+, but not Na+, in sos1-1 mutant seedlings, and increased Li+ tolerance of both the sos1-1 mutant and wild-type seedlings. Results of Li+ and K+ measurement of loss-of-function and gain-of-function mutants indicate that AtNHX8 may be responsible for Li+ extrusion, and may be able to maintain K+ acquisition and intracellular ion homeostasis. Subcellular localization of the AtNHX8-enhanced green fluorescent protein (EGFP) fusion protein suggested that AtNHX8 protein is targeted to the plasma membrane. Taken together, our findings suggest that AtNHX8 encodes a putative plasma membrane Li+/H+ antiporter that functions in Li detoxification and ion homeostasis in Arabidopsis.

Original languageEnglish (US)
Pages (from-to)718-728
Number of pages11
JournalPlant Journal
Volume49
Issue number4
DOIs
StatePublished - Feb 1 2007

Fingerprint

Antiporters
Monovalent Cations
antiporters
Arabidopsis
Protons
Arabidopsis thaliana
Ions
mutants
Cell Membrane
Seedlings
plasma membrane
ions
Homeostasis
homeostasis
Sodium-Hydrogen Antiporter
Cesium
Proteins
Lithium
cesium
lithium

All Science Journal Classification (ASJC) codes

  • Genetics
  • Plant Science
  • Cell Biology

Cite this

An, Rui ; Chen, Qi Jun ; Chai, Mao Feng ; Lu, Ping Li ; Su, Zhao ; Qin, Zhi Xiang ; Chen, Jia ; Wang, Xue Chen. / AtNHX8, a member of the monovalent cation:proton antiporter-1 family in Arabidopsis thaliana, encodes a putative Li+/H+ antiporter. In: Plant Journal. 2007 ; Vol. 49, No. 4. pp. 718-728.
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abstract = "The Arabidopsis monovalent cation:proton antiporter-1 (CPA1) family includes eight members, AtNHX1-8. AtNHX1 and AtNHX7/SOS1 have been well characterized as tonoplast and plasma membrane Na+/H+ antiporters, respectively. The proteins AtNHX2-6 have been phylogenetically linked to AtNHX1, while AtNHX8 appears to be related to AtNHX7/SOS1. Here we report functional characterization of AtNHX8. AtNHX8 T-DNA insertion mutants are hypersensitive to lithium ions (Li+) relative to wild-type plants, but not to the other metal ions such as sodium (Na+), potassium (K+) and caesium (Cs+). AtNHX8 overexpression in a triple-deletion yeast mutant AXT3 that exhibits defective Na+/Li + transport specifically suppresses sensitivity to Li+, but does not affect Na+ sensitivity. Likewise, AtNHX8 overexpression complemented sensitivity to Li+, but not Na+, in sos1-1 mutant seedlings, and increased Li+ tolerance of both the sos1-1 mutant and wild-type seedlings. Results of Li+ and K+ measurement of loss-of-function and gain-of-function mutants indicate that AtNHX8 may be responsible for Li+ extrusion, and may be able to maintain K+ acquisition and intracellular ion homeostasis. Subcellular localization of the AtNHX8-enhanced green fluorescent protein (EGFP) fusion protein suggested that AtNHX8 protein is targeted to the plasma membrane. Taken together, our findings suggest that AtNHX8 encodes a putative plasma membrane Li+/H+ antiporter that functions in Li detoxification and ion homeostasis in Arabidopsis.",
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AtNHX8, a member of the monovalent cation:proton antiporter-1 family in Arabidopsis thaliana, encodes a putative Li+/H+ antiporter. / An, Rui; Chen, Qi Jun; Chai, Mao Feng; Lu, Ping Li; Su, Zhao; Qin, Zhi Xiang; Chen, Jia; Wang, Xue Chen.

In: Plant Journal, Vol. 49, No. 4, 01.02.2007, p. 718-728.

Research output: Contribution to journalArticle

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AU - An, Rui

AU - Chen, Qi Jun

AU - Chai, Mao Feng

AU - Lu, Ping Li

AU - Su, Zhao

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AU - Chen, Jia

AU - Wang, Xue Chen

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AB - The Arabidopsis monovalent cation:proton antiporter-1 (CPA1) family includes eight members, AtNHX1-8. AtNHX1 and AtNHX7/SOS1 have been well characterized as tonoplast and plasma membrane Na+/H+ antiporters, respectively. The proteins AtNHX2-6 have been phylogenetically linked to AtNHX1, while AtNHX8 appears to be related to AtNHX7/SOS1. Here we report functional characterization of AtNHX8. AtNHX8 T-DNA insertion mutants are hypersensitive to lithium ions (Li+) relative to wild-type plants, but not to the other metal ions such as sodium (Na+), potassium (K+) and caesium (Cs+). AtNHX8 overexpression in a triple-deletion yeast mutant AXT3 that exhibits defective Na+/Li + transport specifically suppresses sensitivity to Li+, but does not affect Na+ sensitivity. Likewise, AtNHX8 overexpression complemented sensitivity to Li+, but not Na+, in sos1-1 mutant seedlings, and increased Li+ tolerance of both the sos1-1 mutant and wild-type seedlings. Results of Li+ and K+ measurement of loss-of-function and gain-of-function mutants indicate that AtNHX8 may be responsible for Li+ extrusion, and may be able to maintain K+ acquisition and intracellular ion homeostasis. Subcellular localization of the AtNHX8-enhanced green fluorescent protein (EGFP) fusion protein suggested that AtNHX8 protein is targeted to the plasma membrane. Taken together, our findings suggest that AtNHX8 encodes a putative plasma membrane Li+/H+ antiporter that functions in Li detoxification and ion homeostasis in Arabidopsis.

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