[Seminar] Regulation of potassium uptake and storage

Seminar

Title: Regulation of potassium uptake and storage

Speaker: Jose M. Pardo

Affiliation: Instituto de Bioquimica Vegetal y Fotosintesis (IBVF-CSIC), Sevilla, Spain

Abstract:

Potassium (K) is an essential nutrient for every living organism, but in plants K reaches organismal contents of up to 10% of dry weight. The avidity that plants have for K is a key issue in agriculture. While cytosolic K is kept at homeostatic concentrations close to 100 mM, surplus K is stored in cell vacuoles in large quantities. An array of K transporters and direct regulators (protein kinases and phosphatases, interacting proteins, diffusive chemical messengers) have been identified as the basic elements underpinning K fluxes, but the regulatory networks involved in controlling K homeostasis in individual cells and whole organisms remain largely unknown. Current evidence indicates that active K uptake (i.e., against the electrochemical K gradient) involves K-H symporters at the plasma membrane (HAK, High-Affinity K transporters) and K/H antiporters (NHX) at the tonoplast [1-3]. These transporters, together with K-selective channels that fine-tune the membrane electrical potential by K uptake and release, share common regulators that are focal effectors of K nutrition [4-6].

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2. Barragan, V., et al., Ion Exchangers NHX1 and NHX2 Mediate Active Potassium Uptake into Vacuoles to Regulate Cell Turgor and Stomatal Function in Arabidopsis. Plant Cell, 2012. 24: p. 1127-42.
3. Andrés, Z., et al., Control of vacuolar dynamics and regulation of stomatal aperture by tonoplast potassium uptake. Proceedings of the National Academy of Sciences USA, 2014. 111(17): p. E1806-E1814.
4. Xu, J., et al., A protein kinase, interacting with two calcineurin B-like proteins, regulates K+ transporter AKT1 in Arabidopsis. Cell, 2006. 125(7): p. 1347-1360.
5. Li, L., et al., A Ca2+ signaling pathway regulates a K+ channel for low-K response in Arabidopsis. Proceedings of the National Academy of Sciences, 2006. 103(33): p. 12625-12630.
6. Ragel, P., et al., The CBL-Interacting Protein Kinase CIPK23 Regulates HAK5-Mediated High-Affinity K+ Uptake in Arabidopsis Roots. Plant Physiology, 2015. 169(4): p. 2863-73.