Abstract
The cDNAs CnHAK1 and CnHAK2, encoding K+ transporters, were amplified from the leaves of the seagrass Cymodocea nodosa. None of these transporters suppressed the K+ deficiency of a Saccharomyces cerevisiae mutant, but both suppressed the equivalent defect of an Escherichia coli mutant. Overexpression of the transporter CnHAK1, but not CnHAK2, mediated very rapid K+ or Rb+ influxes in the E. coli mutant. The concentration dependence of these influxes demonstrated that CnHAK1 is a low-affinity K+ transporter, which does not discriminate between K+ and Rb+. CnHAK1 expressed in E. coli worked in reverse when the external K+ concentrations were low, and we established the condition of a simple functional test of K+ loss for transporters of the Kup-HAK family. In comparison with its homologue barley transporter HvHAK2, CnHAK1 was insensitive to Na+.
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Garciadeblas, B., Benito, B. & Rodríguez-Navarro, A. Molecular cloning and functional expression in bacteria of the potassium transporters CnHAK1 and CnHAK2 of the seagrass Cymodocea nodosa . Plant Mol Biol 50, 623–633 (2002). https://doi.org/10.1023/A:1019951023362
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DOI: https://doi.org/10.1023/A:1019951023362