The role of K+ channels in uptake and redistribution of potassium in the model plant Arabidopsis thaliana

Sharma, Tripti; Drèyer, Ingo; Riedelsberger, Janin

doi:10.3389/fpls.2013.00224

Cited by 137 publications

(135 citation statements)

References 139 publications

(219 reference statements)

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“…K ? channels are by far the best characterized enzymes in terms of regulation of ionic input and output, second messengers and transport (Sharma et al 2013). However, little is known about permease-type transporters and antiporters (Gómez-Porras et al 2012).…”

Section: Potassium (K)mentioning

confidence: 99%

Plant and microbe genomics and beyond: potential for developing a novel molecular plant nutrition approach

2015

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Classical soil science approaches have enabled us to establish basic principles of how the soil system functions and have answered numerous practical agricultural application questions. In recent years, efforts have been refocused on better understanding, managing and benefiting from this system that contains one of the most complex biological communities of the planet. Soil biology is seen as being at the center of scientific research of this century, with novel research objectives and goals being set. In addition, plant nutrition has enabled us to understand nutrient uptake, transport and mobilization mechanisms in plants, and both disciplines have converged on the area of microorganism-mediated plant nutrition. The challenge for these scientific areas is to identify microorganism communities and the roles they play in their habitats, as well as the mechanisms that plants have to make better use of nutrients. Genomics and metagenomics, along with microbiological techniques, are contributing greatly to advances in our understanding of living systems that exist in the soil and their interaction with plants. For its part, molecular plant nutrition has made significant progress in understanding the use of nutrients by plant cells, and has identified molecular mechanisms that can improve nutrient use efficiency. Together, molecular soil microbiology and molecular plant nutrition are projected to be a driving force in agriculture and sustainable food production in the coming years. Herewith, we aim to integrate recent literature on basic and applied research concerning plant and microbe genomics in terms of their potential for developing a novel molecular plant nutrition approach, with special emphasis on nitrogen, potassium and phosphorous as the major macronutrients for crop plants.

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Section: Potassium (K)mentioning

confidence: 99%

Plant and microbe genomics and beyond: potential for developing a novel molecular plant nutrition approach

2015

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“…[1][2][3] The genome of the model plant Arabidopsis thaliana contains seven genes coding for voltagedependent K C channel subunits. A functional plant K C channel is built of four a-subunits.…”

Section: Introductionmentioning

confidence: 99%

Identification of regions responsible for the function of the plant K⁺ channels KAT1 and AKT2 in Saccharomyces cerevisiae and Xenopus laevis oocytes

et al. 2017

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The Arabidopsis K C channel KAT1 complements in K C -limited medium the growth of the K C uptake defective Saccharomyces cerevisiae mutant strain CY162, while another K C channel, AKT2, does not. To gain insight into the structural basis for this difference, we constructed 12 recombinant chimeric channels from these two genes. When expressed in CY162, only three of these chimeras fully rescued the growth of CY162 under K C -limited conditions. We conclude that the transmembrane core region of KAT1 is important for its activity in S. cerevisiae. This involves not only the pore region but also parts of its voltage-sensor domain.

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“…A Shaker subunit comprises a short N-terminal sequence, six transmembrane segments (S1-S6), a pore domain between S5 and S6, and a large intracytoplasmic C-terminal region that comprises about two-thirds of the protein, including a C-linker involved in channel targeting and activity (23), a cyclic nucleotide-binding domain (CNBD), an ankyrin protein-protein interaction domain (absent in KAT1, KAT2, and AtKC1), and a K HA (HA for hydrophobic/acidic) domain (24). Depending on the subunits used, inwardly or outwardly rectifying channels can be formed (25,26). Most genes encoding subunits involved in inwardly rectifying channel assembly (KAT1, KAT2, AKT1, and AKT2) are expressed in guard cells (5,27,28), whereas GORK is the only outwardly rectifying channel in this cell type (29).…”

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confidence: 99%

“…GORK is also located in these cells, although its role remains elusive. GORK may initiate plasma membrane repolarization after depolarization evoked by environmental changes (26,31).…”

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confidence: 99%

“…Previous studies have shown that GORK and its SKOR (stelar K ϩ outward rectifier) homolog are sensitive to different signaling factors, such as reactive oxygen species (31,36,37), external K ϩ (26,38,39), and internal and external pH (38,40), and that clustering of GORK channels is correlated with changes in its gating properties (41). Regarding PP2Cs, early physiological studies in guard cells of Nicotiana benthamiana provided evidence that outward K ϩ fluxes were not driven only by depolarization and that PP2C phosphatases could take part in their control.…”

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The Arabidopsis AtPP2CA Protein Phosphatase Inhibits the GORK K+ Efflux Channel and Exerts a Dominant Suppressive Effect on Phosphomimetic-activating Mutations

Lefoulon

Boeglin

Moreau

et al. 2016

Journal of Biological Chemistry

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The regulation of the GORK (Guard Cell Outward Rectifying) Shaker channel mediating a massive K ؉ efflux in Arabidopsis guard cells by the phosphatase AtPP2CA was investigated. Unlike the gork mutant, the atpp2ca mutants displayed a phenotype of reduced transpiration. We found that AtPP2CA interacts physically with GORK and inhibits GORK activity in Xenopus oocytes. Several amino acid substitutions in the AtPP2CA active site, including the dominant interfering G145D mutation, disrupted the GORK-AtPP2CA interaction, meaning that the native conformation of the AtPP2CA active site is required for the GORKAtPP2CA interaction. Furthermore, two serines in the GORK ankyrin domain that mimic phosphorylation (Ser to Glu) or dephosphorylation (Ser to Ala) were mutated. Mutations mimicking phosphorylation led to a significant increase in GORK activity, whereas mutations mimicking dephosphorylation had no effect on GORK. In Xenopus oocytes, the interaction of AtPP2CA with "phosphorylated" or "dephosphorylated" GORK systematically led to inhibition of the channel to the same baseline level. Single-channel recordings indicated that the GORK S722E mutation increases the open probability of the channel in the absence, but not in the presence, of AtPP2CA. The dephosphorylation-independent inactivation mechanism of GORK by AtPP2CA is discussed in relation with well known conformational changes in animal Shaker-like channels that lead to channel opening and closing. In plants, PP2C activity would control the stomatal aperture by regulating both GORK and SLAC1, the two main channels required for stomatal closure.The plant clade A protein phosphatases 2C (PP2Cs) 5 are Mg 2ϩ -and Mn 2ϩ -dependent serine/threonine phosphatases that were first identified as components of the abscisic acid (ABA) signal transduction pathway (1, 2). The clade A APP2C members in Arabidopsis are mostly known as negative regulators of ABA signaling (3). Among this clade, ABI1, ABI2 (4), HAB1 (5), and AtPP2CA (6 -8) are well characterized. These proteins are involved in ABA-regulated germination (7-10). Of these, the ABI1, ABI2, and AtPP2CA genes are highly induced by ABA in guard cells (5). The abi1, abi2, atpp2ca, and hab1 mutants exhibit stomatal phenotypes (1, 4, 5). In particular, the atpp2ca-1 mutant displays impaired control of the stomatal aperture in epidermal strips in response to ABA (7). The role of clade A PP2Cs in stomatal closure in response to ABA has been discovered recently (reviewed in Refs. 11,12). Briefly, the Pyrabactin resistance (PYR)/PYR1-like (PYL)/regulatory component of the ABA receptor (RCAR)-soluble ABA receptors undergo a conformational change upon binding ABA, allowing them to bind and inactivate PP2Cs (13-15) and release the SnRK2.6/OST1 kinase. Without ABA, PP2Cs can bind to OST1 and inactivate it (16, 17). Active OST1 mediates anion efflux through the activation of SLAC1 (18,19). This signaling pathway is important for guard cell plasma membrane depolarization, which drives K ϩ efflux and causes stomatal closure. Besides OST...

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The role of K+ channels in uptake and redistribution of potassium in the model plant Arabidopsis thaliana

Cited by 137 publications

References 139 publications

Plant and microbe genomics and beyond: potential for developing a novel molecular plant nutrition approach

Plant and microbe genomics and beyond: potential for developing a novel molecular plant nutrition approach

Identification of regions responsible for the function of the plant K⁺ channels KAT1 and AKT2 in Saccharomyces cerevisiae and Xenopus laevis oocytes

The Arabidopsis AtPP2CA Protein Phosphatase Inhibits the GORK K+ Efflux Channel and Exerts a Dominant Suppressive Effect on Phosphomimetic-activating Mutations

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The role of K+ channels in uptake and redistribution of potassium in the model plant Arabidopsis thaliana

Cited by 137 publications

References 139 publications

Plant and microbe genomics and beyond: potential for developing a novel molecular plant nutrition approach

Plant and microbe genomics and beyond: potential for developing a novel molecular plant nutrition approach

Identification of regions responsible for the function of the plant K+ channels KAT1 and AKT2 in Saccharomyces cerevisiae and Xenopus laevis oocytes

The Arabidopsis AtPP2CA Protein Phosphatase Inhibits the GORK K+ Efflux Channel and Exerts a Dominant Suppressive Effect on Phosphomimetic-activating Mutations

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Identification of regions responsible for the function of the plant K⁺ channels KAT1 and AKT2 in Saccharomyces cerevisiae and Xenopus laevis oocytes