TY  - JOUR
A1  - Banks, Jo Ann
A1  - Nishiyama, Tomoaki
A1  - Hasebe, Mitsuyasu
A1  - Bowman, John L.
A1  - Gribskov, Michael
A1  - dePamphilis, Claude
A1  - Albert, Victor A.
A1  - Aono, Naoki
A1  - Aoyama, Tsuyoshi
A1  - Ambrose, Barbara A.
A1  - Ashton, Neil W.
A1  - Axtell, Michael J.
A1  - Barker, Elizabeth
A1  - Barker, Michael S.
A1  - Bennetzen, Jeffrey L.
A1  - Bonawitz, Nicholas D.
A1  - Chapple, Clint
A1  - Cheng, Chaoyang
A1  - Correa, Luiz Gustavo Guedes
A1  - Dacre, Michael
A1  - DeBarry, Jeremy
A1  - Dreyer, Ingo
A1  - Elias, Marek
A1  - Engstrom, Eric M.
A1  - Estelle, Mark
A1  - Feng, Liang
A1  - Finet, Cedric
A1  - Floyd, Sandra K.
A1  - Frommer, Wolf B.
A1  - Fujita, Tomomichi
A1  - Gramzow, Lydia
A1  - Gutensohn, Michael
A1  - Harholt, Jesper
A1  - Hattori, Mitsuru
A1  - Heyl, Alexander
A1  - Hirai, Tadayoshi
A1  - Hiwatashi, Yuji
A1  - Ishikawa, Masaki
A1  - Iwata, Mineko
A1  - Karol, Kenneth G.
A1  - Koehler, Barbara
A1  - Kolukisaoglu, Uener
A1  - Kubo, Minoru
A1  - Kurata, Tetsuya
A1  - Lalonde, Sylvie
A1  - Li, Kejie
A1  - Li, Ying
A1  - Litt, Amy
A1  - Lyons, Eric
A1  - Manning, Gerard
A1  - Maruyama, Takeshi
A1  - Michael, Todd P.
A1  - Mikami, Koji
A1  - Miyazaki, Saori
A1  - Morinaga, Shin-ichi
A1  - Murata, Takashi
A1  - Müller-Röber, Bernd
A1  - Nelson, David R.
A1  - Obara, Mari
A1  - Oguri, Yasuko
A1  - Olmstead, Richard G.
A1  - Onodera, Naoko
A1  - Petersen, Bent Larsen
A1  - Pils, Birgit
A1  - Prigge, Michael
A1  - Rensing, Stefan A.
A1  - Mauricio Riano-Pachon, Diego
A1  - Roberts, Alison W.
A1  - Sato, Yoshikatsu
A1  - Scheller, Henrik Vibe
A1  - Schulz, Burkhard
A1  - Schulz, Christian
A1  - Shakirov, Eugene V.
A1  - Shibagaki, Nakako
A1  - Shinohara, Naoki
A1  - Shippen, Dorothy E.
A1  - Sorensen, Iben
A1  - Sotooka, Ryo
A1  - Sugimoto, Nagisa
A1  - Sugita, Mamoru
A1  - Sumikawa, Naomi
A1  - Tanurdzic, Milos
A1  - Theissen, Guenter
A1  - Ulvskov, Peter
A1  - Wakazuki, Sachiko
A1  - Weng, Jing-Ke
A1  - Willats, William W. G. T.
A1  - Wipf, Daniel
A1  - Wolf, Paul G.
A1  - Yang, Lixing
A1  - Zimmer, Andreas D.
A1  - Zhu, Qihui
A1  - Mitros, Therese
A1  - Hellsten, Uffe
A1  - Loque, Dominique
A1  - Otillar, Robert
A1  - Salamov, Asaf
A1  - Schmutz, Jeremy
A1  - Shapiro, Harris
A1  - Lindquist, Erika
A1  - Lucas, Susan
A1  - Rokhsar, Daniel
A1  - Grigoriev, Igor V.
T1  - The selaginella genome identifies genetic changes associated with the evolution of vascular plants
JF  - Science
N2  - Vascular plants appeared similar to 410 million years ago, then diverged into several lineages of which only two survive: the euphyllophytes (ferns and seed plants) and the lycophytes. We report here the genome sequence of the lycophyte Selaginella moellendorffii (Selaginella), the first nonseed vascular plant genome reported. By comparing gene content in evolutionarily diverse taxa, we found that the transition from a gametophyte- to a sporophyte-dominated life cycle required far fewer new genes than the transition from a nonseed vascular to a flowering plant, whereas secondary metabolic genes expanded extensively and in parallel in the lycophyte and angiosperm lineages. Selaginella differs in posttranscriptional gene regulation, including small RNA regulation of repetitive elements, an absence of the trans-acting small interfering RNA pathway, and extensive RNA editing of organellar genes.
Y1  - 2011
U6  - https://doi.org/10.1126/science.1203810
SN  - 0036-8075
VL  - 332
IS  - 6032
SP  - 960
EP  - 963
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Dreyer, Ingo
A1  - Blatt, Michael R.
T1  - What makes a gate? : the ins and outs of Kv-like K+ channels in plants
N2  - Gating of K+ and other ion channels is 'hard-wired' within the channel protein. So it remains a puzzle how closely related channels in plants can show an unusually diverse range of biophysical properties. Gating of these channels lies at the heart of K+ mineral nutrition, signalling, abiotic and biotic stress responses in plants. Thus, our knowledge of the molecular mechanics underpinning K+ channel gating will be important for rational engineering of related traits in agricultural crops. Several key studies have added significantly to our understanding of channel gating in plants and have challenged current thinking about analogous processes found in animal K+ channels. Such studies highlight how much of K+ channel gating remains to be explored in plants.
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/13601385
U6  - https://doi.org/10.1016/j.tplants.2009.04.001
SN  - 1360-1385
ER  - 
TY  - JOUR
A1  - Dreyer, Ingo
A1  - Gajdanowicz, Pawel
T1  - Regulation of the gating mode of the Arabidopsis K+ channel AKT2 is important for adaptation to abiotic stress
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/10956433
U6  - https://doi.org/10.1016/j.cbpa.2009.04.426
SN  - 1095-6433
ER  - 
TY  - JOUR
A1  - Dreyer, Ingo
A1  - Poree, Fabien
A1  - Schneider, A.
A1  - Mittelstadt, J.
A1  - Bertl, Adam
A1  - Sentenac, H.
A1  - Thibaud, Jean-Baptiste
A1  - Müller-Röber, Bernd
T1  - Assembly of plant Shaker-like K-out channels requires two distinct sites of the channel alpha-subunit
N2  - SKOR and GORK are outward-rectifying plant potassium channels from Arabidopsis thaliana. They belong to the Shaker superfamily of voltage-dependent K+ channels. Channels of this class are composed of four alpha-subunits and subunit assembly is a prerequisite for channel function. In this study the assembly mechanism of SKOR was investigated using the yeast two-hybrid system and functional assays in Xenopus oocytes and in yeast. We demonstrate that SKOR and GORK physically interact and assemble into heteromeric K-out channels. Deletion mutants and chimeric proteins generated from SKOR and the K-in channel alpha-subunit KAT1 revealed that the cytoplasmic C-terminus of SKOR determines channel assembly. Two domains thatchannel a-subunit KAT1 revealed that the cytoplasmic C-terminus of SKOR determines channel assembly. Two domains that are crucial for channel assembly were identified: i), a proximal interacting region comprising a putative cyclic nucleotide-binding domain together with 33 amino acids just upstream of this domain, and ii), a distal interacting region showing some resemblance to the K-T domain of KAT1. Both regions contributed differently to channel assembly. Whereas the proximal interacting region was found to be active on its own, the distal interacting region required an intact proximal interacting region to be active. K-out alpha-subunits did not assemble with K-in alpha-subunits because of the absence of interaction between their assembly sites
Y1  - 2004
SN  - 0006-3495
ER  - 
TY  - JOUR
A1  - Fernandez-Nino, Miguel
A1  - Giraldo, Daniel
A1  - Lucia Gomez-Porras, Judith
A1  - Dreyer, Ingo
A1  - Gonzalez Barrios, Andres Fernando
A1  - Arevalo-Ferro, Catalina
T1  - A synthetic multi-cellular network of coupled self-sustained oscillators
JF  - PLoS one
N2  - Engineering artificial networks from modular components is a major challenge in synthetic biology. In the past years, single units, such as switches and oscillators, were successfully constructed and implemented. The effective integration of these parts into functional artificial self-regulated networks is currently on the verge of breakthrough. Here, we describe the design of a modular higher-order synthetic genetic network assembled from two independent self-sustained synthetic units: repressilators coupled via a modified quorum-sensing circuit. The isolated communication circuit and the network of coupled oscillators were analysed in mathematical modelling and experimental approaches. We monitored clustering of cells in groups of various sizes. Within each cluster of cells, cells oscillate synchronously, whereas the theoretical modelling predicts complete synchronization of the whole cellular population to be obtained approximately after 30 days. Our data suggest that self-regulated synchronization in biological systems can occur through an intermediate, long term clustering phase. The proposed artificial multicellular network provides a system framework for exploring how a given network generates a specific behaviour.
Y1  - 2017
U6  - https://doi.org/10.1371/journal.pone.0180155
SN  - 1932-6203
VL  - 12
PB  - PLoS
CY  - San Fransisco
ER  - 
TY  - JOUR
A1  - Gajdanowicz, Pawel
A1  - Garcia-Mata, Carlos
A1  - Gonzalez, Wendy
A1  - Morales-Navarro, Samuel Elïas
A1  - Sharma, Tripti
A1  - Gonzalez-Nilo, Fernando Danilo
A1  - Gutowicz, Jan
A1  - Müller-Röber, Bernd
A1  - Blatt, Michael R.
A1  - Dreyer, Ingo
T1  - Distinct roles of the last transmembrane domain in controlling Arabidopsis K+ channel activity
N2  - The family of voltage-gated potassium channels in plants presumably evolved from a common ancestor and includes both inward-rectifying (K-in) channels that allow plant cells to accumulate K+ and outward-rectifying (K-out) channels that mediate K+ efflux. Despite their close structural similarities, the activity of Kin channels is largely independent of K+ and depends only on the transmembrane voltage, whereas that of K-out channels responds to the membrane voltage and the prevailing extracellular K+ concentration. Gating of potassium channels is achieved by structural rearrangements within the last transmembrane domain (S6). Here we investigated the functional equivalence of the S6 helices of the Kin channel KAT1 and the K-out channel SKOR by domain-swapping and site-directed mutagenesis. Channel mutants and chimeras were analyzed after expression in Xenopus oocytes. We identified two discrete regions that influence gating differently in both channels, demonstrating a lack of functional complementarity between KAT1 and SKOR. Our findings are supported by molecular models of KAT1 and SKOR in the open and closed states. The role of the S6 segment in gating evolved differently during specialization of the two channel subclasses, posing an obstacle for the transfer of the K+-sensor from K-out to K-in channels.
Y1  - 2009
UR  - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0028-646X
U6  - https://doi.org/10.1111/j.1469-8137.2008.02749.x
SN  - 0028-646X
ER  - 
TY  - JOUR
A1  - Gajdanowicz, Pawel
A1  - Michard, Erwan
A1  - Sandmann, Michael
A1  - Rocha, Marcio
A1  - Correa, Luiz Gustavo Guedes
A1  - Ramirez-Aguilar, Santiago J.
A1  - Gomez-Porras, Judith L.
A1  - Gonzalez, Wendy
A1  - Thibaud, Jean-Baptiste
A1  - van Dongen, Joost T.
A1  - Dreyer, Ingo
T1  - Potassium (K plus ) gradients serve as a mobile energy source in plant vascular tissues
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - The essential mineral nutrient potassium (K(+)) is the most important inorganic cation for plants and is recognized as a limiting factor for crop yield and quality. Nonetheless, it is only partially understood how K(+) contributes to plant productivity. K(+) is used as a major active solute to maintain turgor and to drive irreversible and reversible changes in cell volume. K(+) also plays an important role in numerous metabolic processes, for example, by serving as an essential cofactor of enzymes. Here, we provide evidence for an additional, previously unrecognized role of K(+) in plant growth. By combining diverse experimental approaches with computational cell simulation, we show that K(+) circulating in the phloem serves as a decentralized energy storage that can be used to overcome local energy limitations. Posttranslational modification of the phloem-expressed Arabidopsis K(+) channel AKT2 taps this "potassium battery," which then efficiently assists the plasma membrane H(+)-ATPase in energizing the transmembrane phloem (re) loading processes.
KW  - channel gating
KW  - energy limiting condition
KW  - phloem reloading
KW  - posttranslational regulation
KW  - potassium channel
Y1  - 2011
U6  - https://doi.org/10.1073/pnas.1009777108
SN  - 0027-8424
VL  - 108
IS  - 2
SP  - 864
EP  - 869
PB  - National Acad. of Sciences
CY  - Washington
ER  - 
TY  - JOUR
A1  - Garcia-Mata, Carlos
A1  - Wang, Jianwen
A1  - Gajdanowicz, Pawel
A1  - Gonzalez, Wendy
A1  - Hills, Adrian
A1  - Donald, Naomi
A1  - Riedelsberger, Janin
A1  - Amtmann, Anna
A1  - Dreyer, Ingo
A1  - Blatt, Michael R.
T1  - A minimal cysteine motif required to activate the SKOR K+ channel of Arabidopsis by the reactive oxygen species H2O2
N2  - Reactive oxygen species (ROS) are essential for development and stress signaling in plants. They contribute to plant defense against pathogens, regulate stomatal transpiration, and influence nutrient uptake and partitioning. Although both Ca2+ and K+ channels of plants are known to be affected, virtually nothing is known of the targets for ROS at a molecular level. Here we report that a single cysteine (Cys) residue within the Kv-like SKOR K+ channel of Arabidopsis thaliana is essential for channel sensitivity to the ROS H2O2. We show that H2O2 rapidly enhanced current amplitude and activation kinetics of heterologously expressed SKOR, and the effects were reversed by the reducing agent dithiothreitol (DTT). Both H2O2 and DTT were active at the outer face of the membrane and current enhancement was strongly dependent on membrane depolarization, consistent with a H2O2-sensitive site on the SKOR protein that is exposed to the outside when the channel is in the open conformation. Cys substitutions identified a single residue, Cys(168) located within the S3 alpha-helix of the voltage sensor complex, to be essential for sensitivity to H2O2. The same Cys residue was a primary determinant for current block by covalent Cys S-methioylation with aqueous methanethiosulfonates. These, and additional data identify Cys168 as a critical target for H2O2, and implicate ROS-mediated control of the K+ channel in regulating mineral nutrient partitioning within the plant.
Y1  - 2010
UR  - http://www.jbc.org/
U6  - https://doi.org/10.1074/jbc.M110.141176
SN  - 0021-9258
ER  - 
TY  - JOUR
A1  - Gonzalez, Wendy
A1  - Riedelsberger, Janin
A1  - Morales-Navarro, Samuel E.
A1  - Caballero, Julio
A1  - Alzate-Morales, Jans H.
A1  - Gonzalez-Nilo, Fernando D.
A1  - Dreyer, Ingo
T1  - The pH sensor of the plant K+-uptake channel KAT1 is built from a sensory cloud rather than from single key amino acids
JF  - The biochemical journal
N2  - The uptake of potassium ions (K+) accompanied by an acidification of the apoplasm is a prerequisite for stomatal opening. The acidification (approximately 2-2.5 pH units) is perceived by voltage-gated inward potassium channels (K-in) that then can open their pores with lower energy cost. The sensory units for extracellular pH in stomatal K-in channels are proposed to be histidines exposed to the apoplasm. However, in the Arabidopsis thaliana stomatal K-in channel KAT1, mutations in the unique histidine exposed to the solvent (His(267)) do not affect the pH dependency. We demonstrate in the present study that His(267) of the KAT1 channel cannot sense pH changes since the neighbouring residue Phe(266) shifts its pK(a) to undetectable values through a cation-pi interaction. Instead, we show that Glu(240) placed in the extracellular loop between transmembrane segments S5 and S6 is involved in the extracellular acid activation mechanism. Based on structural models we propose that this region may serve as a molecular link between the pH- and the voltage-sensor. Like Glu(240), several other titratable residues could contribute to the pH-sensor of KAT1, interact with each other and even connect such residues far away from the voltage-sensor with the gating machinery of the channel.
KW  - Arabidopsis thaliana
KW  - channel protein structure
KW  - channel protein-proton interaction
KW  - KAT1
KW  - pH regulation
KW  - potassium chanel
Y1  - 2012
U6  - https://doi.org/10.1042/BJ20111498
SN  - 0264-6021
VL  - 442
IS  - 7
SP  - 57
EP  - 63
PB  - Portland Press
CY  - London
ER  - 
TY  - JOUR
A1  - Held, Katrin
A1  - Pascaud, Francois
A1  - Eckert, Christian
A1  - Gajdanowicz, Pawel
A1  - Hashimoto, Kenji
A1  - Corratge-Faillie, Claire
A1  - Offenborn, Jan Niklas
A1  - Lacombe, Benoit
A1  - Dreyer, Ingo
A1  - Thibaud, Jean-Baptiste
A1  - Kudla, Jörg
T1  - Calcium-dependent modulation and plasma membrane targeting of the AKT2 potassium channel by the CBL4/CIPK6 calcium sensor/protein kinase complex
JF  - Cell research
N2  - Potassium (K(+)) channel function is fundamental to many physiological processes. However, components and mechanisms regulating the activity of plant K(+) channels remain poorly understood. Here, we show that the calcium (Ca(2+)) sensor CBL4 together with the interacting protein kinase CIPK6 modulates the activity and plasma membrane (PM) targeting of the K(+) channel AKT2 from Arabidopsis thaliana by mediating translocation of AKT2 to the PM in plant cells and enhancing AKT2 activity in oocytes. Accordingly, akt2, cbl4 and cipk6 mutants share similar developmental and delayed flowering phenotypes. Moreover, the isolated regulatory C-terminal domain of CIPK6 is sufficient for mediating CBL4- and Ca(2+)-dependent channel translocation from the endoplasmic reticulum membrane to the PM by a novel targeting pathway that is dependent on dual lipid modifications of CBL4 by myristoylation and palmitoylation. Thus, we describe a critical mechanism of ion-channel regulation where a Ca(2+) sensor modulates K(+) channel activity by promoting a kinase interaction-dependent but phosphorylation-independent translocation of the channel to the PM.
KW  - calcium sensor
KW  - protein kinase
KW  - potassium channel
KW  - signal transduction
Y1  - 2011
U6  - https://doi.org/10.1038/cr.2011.50
SN  - 1001-0602
VL  - 21
IS  - 7
SP  - 1116
EP  - 1130
PB  - Nature Publ. Group
CY  - Shanghai
ER  - 
TY  - JOUR
A1  - Johansson, Ingela
A1  - Wulfetange, Klaas
A1  - Poree, Fabien
A1  - Michard, Erwan
A1  - Gajdanowicz, Pawel
A1  - Lacombe, Benoit
A1  - Sentenac, Herve
A1  - Thibaud, Jean-Baptiste
A1  - Müller-Röber, Bernd
A1  - Blatt, Michael R.
A1  - Dreyer, Ingo
T1  - External K+ modulates the activity of the Arabidopsis potassium channel SKOR via an unusual mechanism
N2  - Plant outward-rectifying K+ channels mediate K+ efflux from guard cells during stomatal closure and from root cells into the xylem for root-shoot allocation of potassium (K). Intriguingly, the gating of these channels depends on the extracellular K+ concentration, although the ions carrying the current are derived from inside the cell. This K+ dependence confers a sensitivity to the extracellular K+ concentration ([K+]) that ensures that the channels mediate K+ efflux only, regardless of the [K+] prevailing outside. We investigated the mechanism of K+-dependent gating of the K+ channel SKOR of Arabidopsis by site-directed mutagenesis. Mutations affecting the intrinsic K+ dependence of gating were found to cluster in the pore and within the sixth transmembrane helix (S6), identifying an 'S6 gating domain' deep within the membrane. Mapping the SKOR sequence to the crystal structure of the voltage-dependent K+ channel KvAP from Aeropyrum pernix suggested interaction between the S6 gating domain and the base of the pore helix, a prediction supported by mutations at this site. These results offer a unique insight into the molecular basis for a physiologically important K+-sensory process in plants
Y1  - 2006
UR  - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0960-7412
U6  - https://doi.org/10.1111/j.1365-313X.2006.02690.X
SN  - 0960-7412
ER  - 
TY  - JOUR
A1  - Lefoulon, Cecile
A1  - Karnik, Rucha
A1  - Honsbein, Annegret
A1  - Gutla, Paul Vijay
A1  - Grefen, Christopher
A1  - Riedelsberger, Janin
A1  - Poblete, Tomas
A1  - Dreyer, Ingo
A1  - Gonzalez, Wendy
A1  - Blatt, Michael R.
T1  - Voltage-sensor transitions of the inward-rectifying K+ channel KAT1 indicate a latching mechanism biased by hydration within the voltage sensor
JF  - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants
N2  - The Kv-like (potassium voltage-dependent) K+ channels at the plasma membrane, including the inward-rectifying KAT1 K+ channel of Arabidopsis (Arabidopsis thaliana), are important targets for manipulating K+ homeostasis in plants. Gating modification, especially, has been identified as a promising means by which to engineer plants with improved characteristics in mineral and water use. Understanding plant K+ channel gating poses several challenges, despite many similarities to that of mammalian Kv and Shaker channel models. We have used site-directed mutagenesis to explore residues that are thought to form two electrostatic countercharge centers on either side of a conserved phenylalanine (Phe) residue within the S2 and S3 alpha-helices of the voltage sensor domain (VSD) of Kv channels. Consistent with molecular dynamic simulations of KAT1, we show that the voltage dependence of the channel gate is highly sensitive to manipulations affecting these residues. Mutations of the central Phe residue favored the closed KAT1 channel, whereas mutations affecting the countercharge centers favored the open channel. Modeling of the macroscopic current kinetics also highlighted a substantial difference between the two sets of mutations. We interpret these findings in the context of the effects on hydration of amino acid residues within the VSD and with an inherent bias of the VSD, when hydrated around a central Phe residue, to the closed state of the channel.
Y1  - 2014
U6  - https://doi.org/10.1104/pp.114.244319
SN  - 0032-0889
SN  - 1532-2548
VL  - 166
IS  - 2
SP  - 960
EP  - U776
PB  - American Society of Plant Physiologists
CY  - Rockville
ER  - 
TY  - JOUR
A1  - Lucia Gomez-Porras, Judith
A1  - Mauricio Riano-Pachon, Diego
A1  - Benito, Begona
A1  - Haro, Rosario
A1  - Sklodowski, Kamil
A1  - Rodriguez-Navarro, Alonso
A1  - Dreyer, Ingo
T1  - Phylogenetic analysis of K+ transporters in bryophytes, lycophytes, and flowering plants indicates a specialization of vascular plants
JF  - Frontiers in plant science
N2  - As heritage from early evolution, potassium (K+) is absolutely necessary for all living cells. It plays significant roles as stabilizer in metabolism and is important for enzyme activation, stabilization of protein synthesis, and neutralization of negative charges on cellular molecules as proteins and nucleic acids. Land plants even enlarged this spectrum of K+ utilization after having gone ashore, despite the fact that K+ is far less available in their new oligotrophic habitats than in sea water. Inevitably, plant cells had to improve and to develop unique transport systems for K+ accumulation and distribution. In the past two decades a manifold of K+ transporters from flowering plants has been identified at the molecular level. The recently published genome of the fern ally Selaginella moellendorffii now helps in providing a better understanding on the molecular changes involved in the colonization of land and the development of the vasculature and the seeds. In this article we present an inventory of K+ transporters of this lycophyte and pigeonhole them together with their relatives from the moss Physcomitrella patens, the monocotyledon Oryza sativa, and two dicotyledonous species, the herbaceous plant Arabidopsis thaliana, and the tree Populus trichocarpa. Interestingly, the transition of green plants from an aqueous to a dry environment coincides with a dramatic reduction in the diversity of voltage-gated potassium channels followed by a diversification on the basis of one surviving K+ channel class. The first appearance of K+ release (K-out) channels in S. moellendorffii that were shown in Arabidopsis to be involved in xylem loading and guard cell closure coincides with the specialization of vascular plants and may indicate an important adaptive step.
KW  - potassium
KW  - transport
KW  - channel
KW  - voltage-dependent
KW  - voltage-independent
KW  - high-affinity
KW  - Selaginella
Y1  - 2012
U6  - https://doi.org/10.3389/fpls.2012.00167
SN  - 1664-462X
VL  - 3
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Michard, Erwan
A1  - Lacombe, Benoît
A1  - Poree, Fabien
A1  - Müller-Röber, Bernd
A1  - Sentenac, Hervé
A1  - Thibaud, Jean-Baptiste
A1  - Dreyer, Ingo
T1  - A unique voltage sensor sensitizes the potassium channel AKT2 to phosphoregulation
N2  - Among all voltage-gated K+ channels from the model plant Arabidopsis thaliana, the weakly rectifying K+ channel (K-weak channel) AKT2 displays unique gating properties. AKT2 is exceptionally regulated by phosphorylation: when nonphosphorylated AKT2 behaves as an inward-rectifying potassium channel; phosphorylation of AKT2 abolishes inward rectification by shifting its activation threshold far positive (>200 mV) so that it closes only at voltages positive of + 100 mV. In its phosphorylated form, AKT2 is thus locked in the open state in the entire physiological voltage range. To understand the molecular grounds of this unique gating behavior, we generated chimeras between AKT2 and the conventional inward-rectifying channel KAT1. The transfer of the pore from KAT1 to AKT2 altered the permeation properties of the channel. However, the gating properties were unaffected, suggesting that the pore region of AKT2 is not responsible for the unique K-weak gating. Instead, a lysine residue in S4, highly conserved among all K-weak channels but absent from other plant K+ channels, was pinpointed in a site-directed mutagenesis approach. Substitution of the lysine by serine or aspartate abolished the "open-lock" characteristic and converted AKT2 into an inward- rectifying channel. Interestingly, phosphoregulation of the mutant AKT2-K197S appeared to be similar to that of the K-in channel KAT1: as suggested by mimicking the phosphorylated and dephosphorylated states, phosphorylation induced a shift of the activation threshold of AKT2-K197S by about +50 mV. We conclude that the lysine residue K197 sensitizes AKT2 to phosphoregulation. The phosphorylation-induced reduction of the activation energy in AKT2 is similar to 6 kT larger than in the K197S mutant. It is discussed that this hypersensitive response of AKT2 to phosphorylation equips a cell with the versatility to establish a potassium gradient and to make efficient use of it
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Naso, Alessia
A1  - Dreyer, Ingo
A1  - Pedemonte, Laura
A1  - Testa, Ilaria
A1  - Gomez-Porras, Judith Lucia
A1  - Usai, Cesare
A1  - Müller-Röber, Bernd
A1  - Diaspro, Alberto
A1  - Gambale, Franco
A1  - Picco, Cristiana
T1  - The role of the C-terminus for functional heteromerization of the plant channel KDC1
N2  - Voltage-gated potassium channels are formed by the assembly of four identical (homotetramer) or different (heterotetramer) subunits. Tetramerization of plant potassium channels involves the C-terminus of the protein. We investigated the role of the C-terminus of KDC1, a Shaker-like inward-rectifying K+ channel that does not form functional homomeric channels, but participates in the formation of heteromeric complexes with other potassium alpha- subunits when expressed in Xenopus oocytes. The interaction of KDC1 with KAT1 was investigated using the yeast two- hybrid system, fluorescence and electrophysiological studies. We found that the KDC1-EGFP fusion protein is not targeted to the plasma membrane of Xenopus oocytes unless it is coexpressed with KAT1. Deletion mutants revealed that the KDC1 C- terminus is involved in heteromerization. Two domains of the C-terminus, the region downstream the putative cyclic nucleotide binding domain and the distal part of the C-terminus called K-HA domain, contributed to a different extent to channel assembly. Whereas the first interacting region of the C-terminus was necessary for channel heteromerization, the removal of the distal KHA domain decreased but did not abolish the formation of heteromeric complexes. Similar results were obtained when coexpressing KDC1 with the KAT1-homolog KDC2 from carrots, thus indicating the physiological significance of the KAT1/KDC1 characterization. Electrophysiological experiments showed furthermore that the heteromerization capacity of KDC1 was negatively influenced by the presence of the enhanced green fluorescence protein fusion.
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/00063495
U6  - https://doi.org/10.1016/j.bpj.2009.02.055
SN  - 0006-3495
ER  - 
TY  - JOUR
A1  - Poree, Fabien
A1  - Wulfetange, K.
A1  - Naso, A.
A1  - Carpaneto, Armando
A1  - Roller, A.
A1  - Natura, G.
A1  - Bertl, Adam
A1  - Sentenac, H.
A1  - Thibaud, Jean-Baptiste
A1  - Dreyer, Ingo
T1  - Plant K-in and K-out channels : Approaching the trait of opposite rectification by analyzing more than 250 KAT1- SKOR chimeras
N2  - Members of the Shaker-like plant K+ channel family share a common structure, but are highly diverse in their function: they behave as either hyperpolarization-activated inward-rectifying (K-in) channels, or leak-like (K-weak) channels, or depolarization-activated outward-rectifying (K-out) channels. Here we created 256 chimeras between the K-in channel KAT1 and the K-out channel SKOR. The chimeras were screened in a potassium-uptake deficient yeast strain to identify those, which mediate potassium inward currents, i.e., which are functionally equivalent to KAT1. This strategy allowed Lis to identify three chimeras which differ from KAT1 in three parts of the polypeptide: the cytosolic N- terminus, the cytosolic C-terminus, and the putative voltage-sensor S4. Additionally, mutations in the K-out Channel SKOR were generated in order to localize molecular entities underlying its depolarization activation. The triple mutant SKOR-D312N-M313L-1314G, carrying amino-acid changes in the S6 segment, was identified as a channel which did not display any rectification in the tested voltage-range. (C) 2005 Elsevier Inc. All rights reserved
Y1  - 2005
SN  - 0006-291X
ER  - 
TY  - JOUR
A1  - Riano-Pachon, Diego Mauricio
A1  - Dreyer, Ingo
A1  - Müller-Röber, Bernd
T1  - Orphan transcripts in Arabidopsis thaliana : identification of several hundred previously unrecognized genes
N2  - Expressed sequence tags (ESTs) represent a huge resource for the discovery of previously unknown genetic information and functional genome assignment. In this study we screened a collection of 178 292 ESTs from Arabidopsis thaliana by testing them against previously annotated genes of the Arabidopsis genome. We identified several hundreds of new transcripts that match the Arabidopsis genome at so far unassigned loci. The transcriptional activity of these loci was independently confirmed by comparison with the Salk Whole Genome Array Data. To a large extent, the newly identified transcriptionally active genomic regions do not encode 'classic' proteins, but instead generate non-coding RNAs and/or small peptide-coding RNAs of presently unknown biological function. More than 560 transcripts identified in this study are not represented by the Affymetrix GeneChip arrays currently widely used for expression profiling in A. thaliana. Our data strongly support the hypothesis that numerous previously unknown genes exist in the Arabidopsis genome
Y1  - 2005
SN  - 0960-7412
ER  - 
TY  - JOUR
A1  - Riedelsberger, Janin
A1  - Dreyer, Ingo
A1  - Gonzalez, Wendy
T1  - Outward Rectification of Voltage-Gated K+ Channels Evolved at Least Twice in Life History
JF  - PLoS one
N2  - Voltage-gated potassium (K+) channels are present in all living systems. Despite high structural similarities in the transmembrane domains (TMD), this K+ channel type segregates into at least two main functional categories-hyperpolarization-activated, inward-rectifying (Kin) and depolarization-activated, outward-rectifying (Kout) channels. Voltage-gated K+ channels sense the membrane voltage via a voltage-sensing domain that is connected to the conduction pathway of the channel. It has been shown that the voltage-sensing mechanism is the same in Kin and Kout channels, but its performance results in opposite pore conformations. It is not known how the different coupling of voltage-sensor and pore is implemented. Here, we studied sequence and structural data of voltage-gated K+ channels from animals and plants with emphasis on the property of opposite rectification. We identified structural hotspots that alone allow already the distinction between Kin and Kout channels. Among them is a loop between TMD S5 and the pore that is very short in animal Kout, longer in plant and animal Kin and the longest in plant Kout channels. In combination with further structural and phylogenetic analyses this finding suggests that outward-rectification evolved twice and independently in the animal and plant kingdom.
Y1  - 2015
U6  - https://doi.org/10.1371/journal.pone.0137600
SN  - 1932-6203
VL  - 10
IS  - 9
PB  - PLoS
CY  - San Fransisco
ER  - 
TY  - JOUR
A1  - Rocchetti, Alessandra
A1  - Sharma, Tripti
A1  - Wulfetange, Camilla
A1  - Scholz-Starke, Joachim
A1  - Grippa, Alexandra
A1  - Carpaneto, Armando
A1  - Dreyer, Ingo
A1  - Vitale, Alessandro
A1  - Czempinski, Katrin
A1  - Pedrazzini, Emanuela
T1  - The putative K+ channel subunit AtKCO3 forms stable dimers in arabidopsis
JF  - Frontiers in plant science
N2  - The permeation pore of K+ channels is formed by four copies of the pore domain. AtKCO3 is the only putative voltage-independent K+ channel subunit of Arabidopsis thaliana with a single pore domain. KCO3-like proteins recently emerged in evolution and, to date, have been found only in the genus Arabidopsis (A. thaliana and A. lyrata). We show that the absence of KCO3 does not cause marked changes in growth under various conditions. Only under osmotic stress we observed reduced root growth of the kco3-1 null-allele line. This phenotype was complemented by expressing a KCO3 mutant with an inactive pore, indicating that the function of KCO3 under osmotic stress does not depend on its direct ability to transport ions. Constitutively overexpressed AtKCO3 or AtKCO3::G FP are efficiently sorted to the tonoplast indicating that the protein is approved by the endoplasmic reticulum quality control. However, vacuoles isolated from transgenic plants do not have significant alterations in current density. Consistently, both AtKCO3 and AtKCO3::GFP are detected as homodimers upon velocity gradient centrifugation, an assembly state that would not allow for activity. We conclude that if AtKCO3 ever functions as a K+ channel, active tetramers are held by particularly weak interactions, are formed only in unknown specific conditions and may require partner proteins.
KW  - Arabidopsis
KW  - membrane proteins
KW  - potassium channels
KW  - protein assembly
KW  - tonoplast
Y1  - 2012
U6  - https://doi.org/10.3389/fpls.2012.00251
SN  - 1664-462X
VL  - 3
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Sato, A
A1  - Gambale, Franco
A1  - Dreyer, Ingo
A1  - Uozumi, N
T1  - Posttranslational inodification affects K+ current of plant K+ channel
Y1  - 2006
ER  - 
TY  - JOUR
A1  - Skłodowski, Kamil
A1  - Riedelsberger, Janin
A1  - Raddatz, Natalia
A1  - Riadi, Gonzalo
A1  - Caballero, Julio
A1  - Chérel, Isabelle
A1  - Schulze, Waltraud
A1  - Graf, Alexander
A1  - Dreyer, Ingo
T1  - The receptor-like pseudokinase MRH1 interacts with the voltage-gated potassium channel AKT2
JF  - Scientific reports
N2  - The potassium channel AKT2 plays important roles in phloem loading and unloading. It can operate as inward-rectifying channel that allows H+-ATPase-energized K+ uptake. Moreover, through reversible post-translational modifications it can also function as an open, K+-selective channel, which taps a ‘potassium battery’, providing additional energy for transmembrane transport processes. Knowledge about proteins involved in the regulation of the operational mode of AKT2 is very limited. Here, we employed a large-scale yeast two-hybrid screen in combination with fluorescence tagging and null-allele mutant phenotype analysis and identified the plasma membrane localized receptor-like kinase MRH1/MDIS2 (AT4G18640) as interaction partner of AKT2. The phenotype of the mrh1-1 knockout plant mirrors that of akt2 knockout plants in energy limiting conditions. Electrophysiological analyses showed that MRH1/MDIS2 failed to exert any functional regulation on AKT2. Using structural protein modeling approaches, we instead gathered evidence that the putative kinase domain of MRH1/MDIS2 lacks essential sites that are indispensable for a functional kinase suggesting that MRH1/MDIS2 is a pseudokinase. We propose that MRH1/MDIS2 and AKT2 are likely parts of a bigger protein complex. MRH1 might help to recruit other, so far unknown partners, which post-translationally regulate AKT2. Additionally, MRH1 might be involved in the recognition of chemical signals.
Y1  - 2017
U6  - https://doi.org/10.1038/srep44611
SN  - 2045-2322
VL  - 7
PB  - Nature Publishing Group
CY  - London
ER  - 
TY  - JOUR
A1  - Voelker, Camilla
A1  - Gomez-Porras, Judith Lucia
A1  - Becker, Dirk
A1  - Hamamoto, Shin
A1  - Uozumi, Nobuyuki
A1  - Gambale, Franco
A1  - Müller-Röber, Bernd
A1  - Czempinski, Katrin
A1  - Dreyer, Ingo
T1  - Roles of tandem-pore K plus channels in plants : a puzzle still to be solved
N2  - The group of voltage-independent K+ channels in Arabidopsis thaliana consists of six members, five tandem-pore channels (TPK1-TPK5) and a single K-ir-like channel (KCO3). All TPK/KCO channels are located at the vacuolar membrane except for TPK4, which was shown to be a plasma membrane channel in pollen. The vacuolar channels interact with 14-3-3 proteins (also called General Regulating Factors, GRFs), indicating regulation at the level of protein-protein interactions. Here we review current knowledge about these ion channels and their genes, and highlight open questions that need to be urgently addressed in future studies to fully appreciate the physiological functions of these ion channels.
Y1  - 2010
UR  - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=1435-8603
U6  - https://doi.org/10.1111/j.1438-8677.2010.00353.x
SN  - 1435-8603
ER  - 
TY  - JOUR
A1  - Wood, C. C.
A1  - Poree, Fabien
A1  - Dreyer, Ingo
A1  - Koehler, G. J.
A1  - Udvardi, M. K.
T1  - Mechanisms of ammonium transport, accumulation, and retention in ooyctes and yeast cells expressing Arabidopsis AtAMT1; 1
N2  - Ammonium is a primary source of N for plants, so knowing how it is transported, stored, and assimilated in plant cells is important for rational approaches to optimise N-use in agriculture. Electrophysiological studies of Arabidopsis AtAMT1;1 expressed in oocytes revealed passive, Delta psi-driven transport of NH4+ through this protein. Expression of AtAMT1;1 in a novel yeast mutant defective in endogenous ammonium transport and vacuolar acidification supported the above mechanism for AtAMT1;1 and revealed a central role for acid vacuoles in storage and retention of ammonia in cells. These results highlight the mechanistic differences between plant AMT proteins and related transporters in bacteria and animal cells, and suggest novel strategies to enhance nitrogen use efficiency in agriculture. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved
Y1  - 2006
UR  - http://www.sciencedirect.com/science/article/pii/S0014579306007332
U6  - https://doi.org/10.1016/j.febslet.2006.06.026
ER  -