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PMID: 9477571 Published · ppublish English Comparative Study Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S.

AtKUP1: an Arabidopsis gene encoding high-affinity potassium transport activity.

The Plant cell ·Vol. 10 ·No. 1 ·1998-01-00 ·Pages 51-62

Kim EJ, Kwak JM, Uozumi N, Schroeder JI

Abstract

Because plants grow under many different types of soil and environmental conditions, we investigated the hypothesis that multiple pathways for K+ uptake exist in plants. We have identified a new family of potassium transporters from Arabidopsis by searching for homologous sequences among the expressed sequence tags of the GenBank database. The deduced amino acid sequences of AtKUP (for Arabidopsis thaliana K+ uptake transporter) cDNAs are highly homologous to the non-plant Kup and HAK1 potassium transporters from Escherichia coli and Schwanniomyces occidentalis, respectively. Interestingly, AtKUP1 and AtKUP2 are able to complement the potassium transport deficiency of an E. coli triple mutant. In addition, transgenic Arabidopsis suspension cells overexpressing AtKUP1 showed increased Rb+ uptake at micromolar concentrations with an apparent K(m) of approximately 22 microM, indicating that AtKUP1 encodes a high-affinity potassium uptake activity in vivo. A small, low-affinity Rb+ uptake component was also detected in AtKUP1-expressing cells. RNA gel blot analysis showed that the various members of the AtKUP family have distinct patterns of expression, with AtKUP3 transcript levels being strongly induced by K+ starvation. It is proposed that plants contain multiple potassium transporters for high-affinity uptake and that the AtKUP family may provide important components of high- and low-affinity K+ nutrition and uptake into various plant cell types.

MeSH Terms
Amino Acid Sequence Animals Arabidopsis/genetics,metabolism Arabidopsis Proteins Biological Transport Carrier Proteins/genetics,metabolism Cation Transport Proteins DNA, Complementary Escherichia coli/genetics Gene Expression Genes, Plant Genetic Complementation Test Models, Molecular Molecular Sequence Data Multigene Family Mutation Oocytes Plant Proteins/genetics,metabolism Plants, Genetically Modified Potassium/metabolism Protein Conformation Recombinant Proteins/metabolism Rubidium/metabolism Sequence Homology, Amino Acid Xenopus
Chemicals
Arabidopsis Proteins Carrier Proteins Cation Transport Proteins DNA, Complementary KUP1 protein, Arabidopsis Plant Proteins Recombinant Proteins Rubidium Potassium
Authors & Affiliations
4 authors, click to expand affiliations / ORCID
Kim E J
Department of Biology, University of California, San Diego, La Jolla 92093, USA. [email protected]
Kwak J M
Uozumi N
Schroeder J I
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Article Info
Journal
The Plant cell
Abbr.
Plant Cell
ISSN
1040-4651
DOI
10.1105/tpc.10.1.51
Email
[email protected]
Published
1998-01-00
Pages
51-62
Language
English
Region
England
NLM ID
9208688
PMCID
PMC143935
Subset
IM
Databases
GENBANK
AF029876
External Links
PubMed source DOI: 10.1105/tpc.10.1.51 PMC Full Text View journal details
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