Skip to main content
PMC home page
The Plant Cell logoLink to The Plant Cell
. 1998 Jan;10(1):63–73. doi: 10.1105/tpc.10.1.63

AtKuP1: a dual-affinity K+ transporter from Arabidopsis.

H H Fu 1, S Luan 1
PMCID: PMC143931  PMID: 9477572

Abstract

Plant roots contain both high- and low-affinity transport systems for uptake of K+ from the soil. In this study, we characterize a K+ transporter that functions in both high- and low-affinity uptake. Using yeast complementation analysis, we isolated a cDNA for a functional K+ transporter from Arabidopsis (referred to as AtKUP1 for Arabidopsis thaliana K+ uptake). When expressed in a yeast mutant, AtKUP1 dramatically increased K+ uptake capacity at both a low and high [K+] range. Kinetic analyses showed that AtKUP1-mediated K+ uptake displays a "biphasic" pattern similar to that observed in plant roots. The transition from the high-affinity phase (K(m) of 44 microM) to the low-affinity phase (K(m) of 11 mM) occurred at 100 to 200 microM external K+. Both low- and high-affinity K+ uptake via AtKUP1 were inhibited by 5 mM or higher concentrations of NaCl. In addition, AtKUP1-mediated K+ uptake was inhibited by K+ channel blockers, including tetraethylammonium, Cs+, and Ba2+. Consistent with a possible function in K+ uptake from the soil, the AtKUP1 gene is primarily expressed in roots. We conclude that the AtKUP1 gene product may function as a K+ transporter in Arabidopsis roots over a broad range of [K+] in the soil.

Full Text

The Full Text of this article is available as a PDF (243.5 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Anderson J. A., Huprikar S. S., Kochian L. V., Lucas W. J., Gaber R. F. Functional expression of a probable Arabidopsis thaliana potassium channel in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A. 1992 May 1;89(9):3736–3740. doi: 10.1073/pnas.89.9.3736. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bañuelos M. A., Klein R. D., Alexander-Bowman S. J., Rodríguez-Navarro A. A potassium transporter of the yeast Schwanniomyces occidentalis homologous to the Kup system of Escherichia coli has a high concentrative capacity. EMBO J. 1995 Jul 3;14(13):3021–3027. doi: 10.1002/j.1460-2075.1995.tb07304.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Becker D. M., Guarente L. High-efficiency transformation of yeast by electroporation. Methods Enzymol. 1991;194:182–187. doi: 10.1016/0076-6879(91)94015-5. [DOI] [PubMed] [Google Scholar]
  4. Bertl A., Anderson J. A., Slayman C. L., Gaber R. F. Use of Saccharomyces cerevisiae for patch-clamp analysis of heterologous membrane proteins: characterization of Kat1, an inward-rectifying K+ channel from Arabidopsis thaliana, and comparison with endogeneous yeast channels and carriers. Proc Natl Acad Sci U S A. 1995 Mar 28;92(7):2701–2705. doi: 10.1073/pnas.92.7.2701. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Blatt M. R. Ion channel gating in plants: physiological implications and integration for stomatal function. J Membr Biol. 1991 Nov;124(2):95–112. doi: 10.1007/BF01870455. [DOI] [PubMed] [Google Scholar]
  6. Cao Y., Ward J. M., Kelly W. B., Ichida A. M., Gaber R. F., Anderson J. A., Uozumi N., Schroeder J. I., Crawford N. M. Multiple genes, tissue specificity, and expression-dependent modulationcontribute to the functional diversity of potassium channels in Arabidopsis thaliana. Plant Physiol. 1995 Nov;109(3):1093–1106. doi: 10.1104/pp.109.3.1093. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Elledge S. J., Mulligan J. T., Ramer S. W., Spottswood M., Davis R. W. Lambda YES: a multifunctional cDNA expression vector for the isolation of genes by complementation of yeast and Escherichia coli mutations. Proc Natl Acad Sci U S A. 1991 Mar 1;88(5):1731–1735. doi: 10.1073/pnas.88.5.1731. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Epstein E., Rains D. W., Elzam O. E. RESOLUTION OF DUAL MECHANISMS OF POTASSIUM ABSORPTION BY BARLEY ROOTS. Proc Natl Acad Sci U S A. 1963 May;49(5):684–692. doi: 10.1073/pnas.49.5.684. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Gassmann W., Schroeder J. I. Inward-Rectifying K+ Channels in Root Hairs of Wheat (A Mechanism for Aluminum-Sensitive Low-Affinity K+ Uptake and Membrane Potential Control). Plant Physiol. 1994 Aug;105(4):1399–1408. doi: 10.1104/pp.105.4.1399. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Gaymard F., Cerutti M., Horeau C., Lemaillet G., Urbach S., Ravallec M., Devauchelle G., Sentenac H., Thibaud J. B. The baculovirus/insect cell system as an alternative to Xenopus oocytes. First characterization of the AKT1 K+ channel from Arabidopsis thaliana. J Biol Chem. 1996 Sep 13;271(37):22863–22870. doi: 10.1074/jbc.271.37.22863. [DOI] [PubMed] [Google Scholar]
  11. Gunn L., Nickoloff J. A. Rapid transfer of low copy-number episomal plasmids from Saccharomyces cerevisiae to Escherichia coli by electroporation. Mol Biotechnol. 1995 Apr;3(2):79–84. doi: 10.1007/BF02789103. [DOI] [PubMed] [Google Scholar]
  12. Kim E. J., Kwak J. M., Uozumi N., Schroeder J. I. AtKUP1: an Arabidopsis gene encoding high-affinity potassium transport activity. Plant Cell. 1998 Jan;10(1):51–62. doi: 10.1105/tpc.10.1.51. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Ko C. H., Gaber R. F. TRK1 and TRK2 encode structurally related K+ transporters in Saccharomyces cerevisiae. Mol Cell Biol. 1991 Aug;11(8):4266–4273. doi: 10.1128/mcb.11.8.4266. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Luan S., Lane W. S., Schreiber S. L. pCyP B: a chloroplast-localized, heat shock-responsive cyclophilin from fava bean. Plant Cell. 1994 Jun;6(6):885–892. doi: 10.1105/tpc.6.6.885. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Maathuis F. J., Sanders D. Contrasting roles in ion transport of two K(+)-channel types in root cells of Arabidopsis thaliana. Planta. 1995;197(3):456–464. doi: 10.1007/BF00196667. [DOI] [PubMed] [Google Scholar]
  16. Maathuis F. J., Sanders D. Mechanism of high-affinity potassium uptake in roots of Arabidopsis thaliana. Proc Natl Acad Sci U S A. 1994 Sep 27;91(20):9272–9276. doi: 10.1073/pnas.91.20.9272. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Müller-Röber B., Ellenberg J., Provart N., Willmitzer L., Busch H., Becker D., Dietrich P., Hoth S., Hedrich R. Cloning and electrophysiological analysis of KST1, an inward rectifying K+ channel expressed in potato guard cells. EMBO J. 1995 Jun 1;14(11):2409–2416. doi: 10.1002/j.1460-2075.1995.tb07238.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Quintero F. J., Blatt M. R. A new family of K+ transporters from Arabidopsis that are conserved across phyla. FEBS Lett. 1997 Sep 29;415(2):206–211. doi: 10.1016/s0014-5793(97)01125-3. [DOI] [PubMed] [Google Scholar]
  19. Rubio F., Gassmann W., Schroeder J. I. Sodium-driven potassium uptake by the plant potassium transporter HKT1 and mutations conferring salt tolerance. Science. 1995 Dec 8;270(5242):1660–1663. doi: 10.1126/science.270.5242.1660. [DOI] [PubMed] [Google Scholar]
  20. Schachtman D. P., Schroeder J. I., Lucas W. J., Anderson J. A., Gaber R. F. Expression of an inward-rectifying potassium channel by the Arabidopsis KAT1 cDNA. Science. 1992 Dec 4;258(5088):1654–1658. doi: 10.1126/science.8966547. [DOI] [PubMed] [Google Scholar]
  21. Schachtman D. P., Schroeder J. I. Structure and transport mechanism of a high-affinity potassium uptake transporter from higher plants. Nature. 1994 Aug 25;370(6491):655–658. doi: 10.1038/370655a0. [DOI] [PubMed] [Google Scholar]
  22. Schleyer M., Bakker E. P. Nucleotide sequence and 3'-end deletion studies indicate that the K(+)-uptake protein kup from Escherichia coli is composed of a hydrophobic core linked to a large and partially essential hydrophilic C terminus. J Bacteriol. 1993 Nov;175(21):6925–6931. doi: 10.1128/jb.175.21.6925-6931.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Schroeder J. I., Ward J. M., Gassmann W. Perspectives on the physiology and structure of inward-rectifying K+ channels in higher plants: biophysical implications for K+ uptake. Annu Rev Biophys Biomol Struct. 1994;23:441–471. doi: 10.1146/annurev.bb.23.060194.002301. [DOI] [PubMed] [Google Scholar]
  24. Sentenac H., Bonneaud N., Minet M., Lacroute F., Salmon J. M., Gaymard F., Grignon C. Cloning and expression in yeast of a plant potassium ion transport system. Science. 1992 May 1;256(5057):663–665. doi: 10.1126/science.1585180. [DOI] [PubMed] [Google Scholar]
  25. Wu S. J., Ding L., Zhu J. K. SOS1, a Genetic Locus Essential for Salt Tolerance and Potassium Acquisition. Plant Cell. 1996 Apr;8(4):617–627. doi: 10.1105/tpc.8.4.617. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Yalovsky S., Trueblood C. E., Callan K. L., Narita J. O., Jenkins S. M., Rine J., Gruissem W. Plant farnesyltransferase can restore yeast Ras signaling and mating. Mol Cell Biol. 1997 Apr;17(4):1986–1994. doi: 10.1128/mcb.17.4.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Plant Cell are provided here courtesy of Oxford University Press

RESOURCES