Regulation of Ion Transporters

Amtmann, Anna; Blatt, Michael R.

doi:10.1002/9780470988862.ch6

Cited by 5 publications

(7 citation statements)

References 231 publications

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“…5 summarizes data for tissue K ϩ concentrations and K ϩ /Na ϩ ratios in the wild-type, skor, and rhd2 mutant Arabidopsis lines assayed 8 days after transfer to fresh medium alone and with the additions of NaCl and H 2 O 2 . We found that K ϩ concentrations in shoot and root tissue of the wild-type plants increased with increasing NaCl in the medium although the K ϩ /Na ϩ ratios decreased significantly, especially in the shoot, consistent with past observations (12,(33)(34)(35). Increasing H 2 O 2 challenge had a similar, albeit much weaker effect.…”

Section: Ros-dependent K ϩ Partitioning Is Suppressed In the Skor Mutsupporting

confidence: 91%

“…Our studies now offer primary evidence that the SKOR K ϩ channel of Arabidopsis is an important target for residue of the channel protein as the minimal requirement for channel regulation by the ROS. Because SKOR is a major pathway for K ϩ transport into the xylem (14) and contributes to charge balance during the loading of other nutrients and metabolites, especially of anions such as NO 3 Ϫ , and their delivery via the transpiration stream, the findings also implicate a mechanistic link between stress-induced ROS production, nutrient partitioning, and long-distance signaling (12,15,31).…”

Section: Discussionmentioning

confidence: 91%

“…Oxidation of Cys residues by H 2 O 2 to form sulfenic acid effects post-translational modifications of proteins generally (1,2), and has an important role in cellular signaling and control of membrane transport in plants (12). H 2 O 2 and related ROS are important signals contributing to root development (4), homeostatic control of guard cell ion channels (5), and regulation of mineral and water flux during nutrient stress (15,36).…”

Section: Discussionmentioning

confidence: 99%

“…It is expressed within the xylem parenchyma of the root where it facilitates K ϩ loading into the xylem (14), thereby contributing directly to K ϩ homeostasis and indirectly, through charge balance, to the transport of other solutes throughout the plant (12,15). Like other members of the Kvlike channel superfamily (16), the functional channel assembles from four monomers with each SKOR monomer incorporating six transmembrane ␣-helices.…”

mentioning

confidence: 99%

“…For example, ROS affect non-selective cation channels during Fucus development (10); they regulate Ca 2ϩ channels and Ca 2ϩ -based signaling (5) as well as voltage-sensitive K ϩ channels of guard cells (11) that are important for stomatal movement; they contribute in responses to drought and pathogen defense (12); and they have been implicated in targeting K ϩ efflux during programmed cell death (13). However, until now virtually nothing has been known of the molecular targets for ROS in plants, nor has a site of action been identified with an ion channel protein.…”

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confidence: 99%

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A Minimal Cysteine Motif Required to Activate the SKOR K+ Channel of Arabidopsis by the Reactive Oxygen Species H2O2*

Garcı́a-Mata

Wang

Gajdanowicz

et al. 2010

Journal of Biological Chemistry

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119

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Reactive oxygen species (ROS) are essential for development and stress signaling in plants. They Reactive oxygen species (ROS) 3 are major signals in virtually every aspect of eukaryotic cell biology (1, 2). In animals, they are important regulators of cell division and muscle contraction among others (3), and in plants they are essential for development (4) and stress signaling, including drought (5, 6) and defense against pathogens (7). Within proteins, ROS target a small subset of amino acids, notably cysteine (Cys) residues, chemically modifying these amino acids and thereby altering protein structure and function (8). Nonetheless, the targeted residues and associated motifs are often poorly defined, the effects wide ranging and protein-specific, thus confounding molecular analyses. Indeed, among the few well documented examples, ROS modifications in mammalian ryanodine-receptor and BK channels have different consequences depending on the positions of the residues targeted (3, 9).For development and signaling in plants, the activities of membrane ion channels are essential, often including their regulation by ROS. For example, ROS affect non-selective cation channels during Fucus development (10); they regulate Ca 2ϩ channels and Ca 2ϩ -based signaling (5) as well as voltage-sensitive K ϩ channels of guard cells (11) that are important for stomatal movement; they contribute in responses to drought and pathogen defense (12); and they have been implicated in targeting K ϩ efflux during programmed cell death (13). However, until now virtually nothing has been known of the molecular targets for ROS in plants, nor has a site of action been identified with an ion channel protein.SKOR is one of two K ϩ channels found in Arabidopsis thaliana that rectify strongly outward, thereby mediating K ϩ efflux from the cell. It is expressed within the xylem parenchyma of the root where it facilitates K ϩ loading into the xylem (14), thereby contributing directly to K ϩ homeostasis and indirectly, through charge balance, to the transport of other solutes throughout the plant (12,15). Like other members of the Kvlike channel superfamily (16), the functional channel assembles from four monomers with each SKOR monomer incorporating six transmembrane ␣-helices. The first four ␣-helices form a positively charged voltage-sensor complex or "paddle" that moves within the membrane in response to voltage and couples this movement to the channel gate. The fifth and sixth ␣-helices line the aqueous pore through the membrane and assemble in a diaphragm or "gate" at the inner membrane surface, which opens/closes to regulate ion flux through the channel. Here we report that K ϩ current through the heterologously expressed SKOR is modulated by H 2 O 2 , thereby identifying the K ϩ channel as a potential target for ROS, and we show that a single Cys within the voltage sensor complex is essential for its ROS sen-

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Section: Ros-dependent K ϩ Partitioning Is Suppressed In the Skor Mutsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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A Minimal Cysteine Motif Required to Activate the SKOR K+ Channel of Arabidopsis by the Reactive Oxygen Species H2O2*

Garcı́a-Mata

Wang

Gajdanowicz

et al. 2010

Journal of Biological Chemistry

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119

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Ion Transport at the Plant Plasma Membrane

Blatt

2008

Encyclopedia of Life Sciences

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Ion Transport at the Plant Plasma Membrane

Wang

Blatt

Chen

2018

Encyclopedia of Life Sciences

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Membrane transport plays a fundamental role in virtually every aspect of homeostasis, signalling, growth and development in plants. At the plasma membrane, the boundary with the outside world, ion and solute fluxes underpin inorganic mineral nutrient uptake, they trigger rapid changes in second messengers such as cytosolic‐free Ca 2+ concentrations and they power the osmotic gradients that drive cell expansion, to name just a few roles. Our understanding of the transporters – the ion pumps that generate an H + electrochemical driving force, H + ion‐coupled symport and antiport systems and ion channels – now, more than ever, builds on developments in molecular genetics, genomics, protein chemistry and crystallography to gain insights into the fine structure and mechanics of these remarkable enzymes. Even so, it is the interface with the biophysical detail of ion transport that drives scientific enquiry in the field and will continue to be essential in informing both the most fundamental research as well as efforts to apply the knowledge gained in resolving some of the dilemmas that face society today. Key Concepts Study of ion transport is the key for our understanding of mineral nutrition in plants. Ion transporters and their biophysical properties form the basis for understanding of the membrane potentials. Plasma membrane H + ‐ATPase of plants and the Na + /K + ‐ATPase of animals are both members of the P‐type membrane ATPase superfamily. The transport of many solutes is coupled by H + across plasma membrane of plant cells. Ion channels carry much larger current than pumps and cotransporters on a unit protein basis. Membrane vesicle traffic regulates ion transport by controlling the population and availability of transporters at the membrane and, in some cases, by direct binding with ion transporters. Plasma membrane ion transporters have coevolved with the evolution of land plants.

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Regulation of Ion Transporters

Cited by 5 publications

References 231 publications

A Minimal Cysteine Motif Required to Activate the SKOR K+ Channel of Arabidopsis by the Reactive Oxygen Species H2O2*

A Minimal Cysteine Motif Required to Activate the SKOR K+ Channel of Arabidopsis by the Reactive Oxygen Species H2O2*

Ion Transport at the Plant Plasma Membrane

Ion Transport at the Plant Plasma Membrane

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