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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 -