@inproceedings{GonzalezRiedelsbergerMoralesNavarroetal.2012,
  author    = {Gonzalez, W. and Riedelsberger, J. and Morales-Navarro, S. E. and Caballero, Julio and Alzate-Morales, Jans H. and Gonzalez-Nilo, F. D. and Dreyer, Ingo},
  title     = {The pH sensor of the plant K plus uptake channel KAT1 is built from a sensory cloud rather than from single key amino acids},
  series = {The FEBS journal},
  volume    = {279},
  booktitle = {The FEBS journal},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1742-464X},
  pages     = {455 -- 455},
  year      = {2012},
  language  = {en}
}
@misc{SharmaDreyerRiedelsberger2013,
  author    = {Sharma, Tripti and Dreyer, Ingo and Riedelsberger, Janin},
  title     = {The role of K+ channels in uptake and redistribution of potassium in the model plant Arabidopsis thaliana},
  series = {Frontiers in plant science},
  volume    = {4},
  journal   = {Frontiers in plant science},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {1664-462X},
  doi       = {10.3389/fpls.2013.00224},
  pages     = {16},
  year      = {2013},
  abstract  = {Potassium (K+) is inevitable for plant growth and development. It plays a crucial role in the regulation of enzyme activities, in adjusting the electrical membrane potential and the cellular turgor, in regulating cellular homeostasis and in the stabilization of protein synthesis. Uptake of K+ from the soil and its transport to growing organs is essential for a healthy plant development. Uptake and allocation of K+ are performed by K+ channels and transporters belonging to different protein families. In this review we summarize the knowledge on the versatile physiological roles of plant K+ channels and their behavior under stress conditions in the model plant Arabidopsis thaliana.},
  language  = {en}
}
@article{GarciaMataWangGajdanowiczetal.2010,
  author    = {Garcia-Mata, Carlos and Wang, Jianwen and Gajdanowicz, Pawel and Gonzalez, Wendy and Hills, Adrian and Donald, Naomi and Riedelsberger, Janin and Amtmann, Anna and Dreyer, Ingo and Blatt, Michael R.},
  title     = {A minimal cysteine motif required to activate the SKOR K+ channel of Arabidopsis by the reactive oxygen species H2O2},
  issn      = {0021-9258},
  doi       = {10.1074/jbc.M110.141176},
  year      = {2010},
  abstract  = {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.},
  language  = {en}
}
@article{NasoDreyerPedemonteetal.2009,
  author    = {Naso, Alessia and Dreyer, Ingo and Pedemonte, Laura and Testa, Ilaria and Gomez-Porras, Judith Lucia and Usai, Cesare and M{\"u}ller-R{\"o}ber, Bernd and Diaspro, Alberto and Gambale, Franco and Picco, Cristiana},
  title     = {The role of the C-terminus for functional heteromerization of the plant channel KDC1},
  issn      = {0006-3495},
  doi       = {10.1016/j.bpj.2009.02.055},
  year      = {2009},
  abstract  = {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.},
  language  = {en}
}
@article{GajdanowiczGarciaMataGonzalezetal.2009,
  author    = {Gajdanowicz, Pawel and Garcia-Mata, Carlos and Gonzalez, Wendy and Morales-Navarro, Samuel El{\"i}as and Sharma, Tripti and Gonzalez-Nilo, Fernando Danilo and Gutowicz, Jan and M{\"u}ller-R{\"o}ber, Bernd and Blatt, Michael R. and Dreyer, Ingo},
  title     = {Distinct roles of the last transmembrane domain in controlling Arabidopsis K+ channel activity},
  issn      = {0028-646X},
  doi       = {10.1111/j.1469-8137.2008.02749.x},
  year      = {2009},
  abstract  = {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.},
  language  = {en}
}
@article{DreyerBlatt2009,
  author    = {Dreyer, Ingo and Blatt, Michael R.},
  title     = {What makes a gate? : the ins and outs of Kv-like K+ channels in plants},
  issn      = {1360-1385},
  doi       = {10.1016/j.tplants.2009.04.001},
  year      = {2009},
  abstract  = {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.},
  language  = {en}
}
@article{VoelkerGomezPorrasBeckeretal.2010,
  author    = {Voelker, Camilla and Gomez-Porras, Judith Lucia and Becker, Dirk and Hamamoto, Shin and Uozumi, Nobuyuki and Gambale, Franco and M{\"u}ller-R{\"o}ber, Bernd and Czempinski, Katrin and Dreyer, Ingo},
  title     = {Roles of tandem-pore K plus channels in plants : a puzzle still to be solved},
  issn      = {1435-8603},
  doi       = {10.1111/j.1438-8677.2010.00353.x},
  year      = {2010},
  abstract  = {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.},
  language  = {en}
}
@article{DreyerPoreeSchneideretal.2004,
  author    = {Dreyer, Ingo and Poree, Fabien and Schneider, A. and Mittelstadt, J. and Bertl, Adam and Sentenac, H. and Thibaud, Jean-Baptiste and M{\"u}ller-R{\"o}ber, Bernd},
  title     = {Assembly of plant Shaker-like K-out channels requires two distinct sites of the channel alpha-subunit},
  issn      = {0006-3495},
  year      = {2004},
  abstract  = {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},
  language  = {en}
}
@article{RianoPachonDreyerMuellerRoeber2005,
  author    = {Riano-Pachon, Diego Mauricio and Dreyer, Ingo and M{\"u}ller-R{\"o}ber, Bernd},
  title     = {Orphan transcripts in Arabidopsis thaliana : identification of several hundred previously unrecognized genes},
  issn      = {0960-7412},
  year      = {2005},
  abstract  = {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},
  language  = {en}
}
@article{PoreeWulfetangeNasoetal.2005,
  author    = {Poree, Fabien and Wulfetange, K. and Naso, A. and Carpaneto, Armando and Roller, A. and Natura, G. and Bertl, Adam and Sentenac, H. and Thibaud, Jean-Baptiste and Dreyer, Ingo},
  title     = {Plant K-in and K-out channels : Approaching the trait of opposite rectification by analyzing more than 250 KAT1- SKOR chimeras},
  issn      = {0006-291X},
  year      = {2005},
  abstract  = {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},
  language  = {en}
}