Channel-mediated high-affinity K+ uptake into guard cells from Arabidopsis.

Brüggemann L, Dietrich P, Becker D, Dreyer I, Palme K, Hedrich R (1999)

Publication Language: English

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 1999

Journal

Proceedings of the National Academy of Sciences of the United States of America National Academy of Sciences

Book Volume: 96

Pages Range: 3298-302

Journal Issue: 6

DOI: 10.1073/pnas.96.6.3298

Abstract

Potassium uptake by higher plants is the result of high- or low-affinity transport accomplished by different sets of transporters. Although K+ channels were thought to mediate low-affinity uptake only, the molecular mechanism of the high-affinity, proton-dependent K+ uptake system is still scant. Taking advantage of the high-current resolution of the patch-clamp technique when applied to the small Arabidopsis thaliana guard cells densely packed with voltage-dependent K+ channels, we could directly record channels working in the concentration range of high-affinity K+ uptake systems. Here we show that the K+ channel KAT1 expressed in Arabidopsis guard cells and yeast is capable of mediating potassium uptake from media containing as little as 10 microM of external K+. Upon reduction of the external K+ content to the micromolar level the voltage dependence of the channel remained unaffected, indicating that this channel type represents a voltage sensor rather than a K+-sensing valve. This behavior results in K+ release through K+ uptake channels whenever the Nernst potential is negative to the activation threshold of the channel. In contrast to the H+-coupled K+ symport shown to account for high-affinity K+ uptake in roots, pH-dependent K+ uptake into guard cells is a result of a shift in the voltage dependence of the K+ channel. We conclude that plant K+ channels activated by acid pH may play an essential role in K+ uptake even from dilute solutions.

Authors with CRIS profile

Petra Dietrich Professur für Zellbiologie der Pflanzen

Involved external institutions

Julius-Maximilians-Universität Würzburg DE Germany (DE) Max-Delbrück-Centrum für Molekulare Medizin / Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch DE Germany (DE)

How to cite

APA:

Brüggemann, L., Dietrich, P., Becker, D., Dreyer, I., Palme, K., & Hedrich, R. (1999). Channel-mediated high-affinity K+ uptake into guard cells from Arabidopsis. Proceedings of the National Academy of Sciences of the United States of America, 96(6), 3298-302. https://dx.doi.org/10.1073/pnas.96.6.3298

MLA:

Brüggemann, Lioubov, et al. "Channel-mediated high-affinity K+ uptake into guard cells from Arabidopsis." Proceedings of the National Academy of Sciences of the United States of America 96.6 (1999): 3298-302.

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