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Pérez‐Alonso M, Guerrero‐Galán C, González Ortega‐Villaizán A, Ortiz‐García P, Scholz SS, Ramos P, Sakakibara H, Kiba T, Ludwig‐Müller J, Krapp A, Oelmüller R, Vicente‐Carbajosa J, Pollmann S. The calcium sensor CBL7 is required for Serendipita indica-induced growth stimulation in Arabidopsis thaliana, controlling defense against the endophyte and K + homoeostasis in the symbiosis. PLANT, CELL & ENVIRONMENT 2022; 45:3367-3382. [PMID: 35984078 PMCID: PMC9804297 DOI: 10.1111/pce.14420] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 08/02/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
Calcium is an important second messenger in plants. The activation of Ca2+ signalling cascades is critical in the activation of adaptive processes in response to environmental stimuli. Root colonization by the growth promoting endophyte Serendipita indica involves the increase of cytosolic Ca2+ levels in Arabidopsis thaliana. Here, we investigated transcriptional changes in Arabidopsis roots during symbiosis with S. indica. RNA-seq profiling disclosed the induction of Calcineurin B-like 7 (CBL7) during early and later phases of the interaction. Consistently, reverse genetic evidence highlighted the functional relevance of CBL7 and tested the involvement of a CBL7-CBL-interacting protein kinase 13 signalling pathway. The loss-of-function of CBL7 abolished the growth promoting effect and affected root colonization. The transcriptomics analysis of cbl7 revealed the involvement of this Ca2+ sensor in activating plant defense responses. Furthermore, we report on the contribution of CBL7 to potassium transport in Arabidopsis. We analysed K+ contents in wild-type and cbl7 plants and observed a significant increase of K+ in roots of cbl7 plants, while shoot tissues demonstrated K+ depletion. Taken together, our work associates CBL7 with an important role in the mutual interaction between Arabidopsis and S. indica and links CBL7 to K+ transport.
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Affiliation(s)
- Marta‐Marina Pérez‐Alonso
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)–Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA/CSIC)Campus de MontegancedoPozuelo de Alarcón (Madrid)Spain
- Umeå Plant Science CenterUmeå UniversityUmeåSweden
| | - Carmen Guerrero‐Galán
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)–Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA/CSIC)Campus de MontegancedoPozuelo de Alarcón (Madrid)Spain
| | - Adrián González Ortega‐Villaizán
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)–Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA/CSIC)Campus de MontegancedoPozuelo de Alarcón (Madrid)Spain
| | - Paloma Ortiz‐García
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)–Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA/CSIC)Campus de MontegancedoPozuelo de Alarcón (Madrid)Spain
| | - Sandra S. Scholz
- Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular BotanyFriedrich‐Schiller‐University JenaJenaGermany
| | - Patricio Ramos
- Centro de Investigación de Estudios Avanzados del MauleUniversidad Católica del MauleTalcaChile
| | - Hitoshi Sakakibara
- RIKEN Center for Sustainable Resource ScienceTsurumiYokohamaJapan
- Department of Applied Biosciences, Graduate School of Bioagricultural SciencesNagoya UniversityNagoyaJapan
| | - Takatoshi Kiba
- RIKEN Center for Sustainable Resource ScienceTsurumiYokohamaJapan
- Department of Applied Biosciences, Graduate School of Bioagricultural SciencesNagoya UniversityNagoyaJapan
| | | | - Anne Krapp
- Université Paris‐Saclay, INRAE, AgroParisTechInstitut Jean‐Pierre BourginVersaillesFrance
| | - Ralf Oelmüller
- Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular BotanyFriedrich‐Schiller‐University JenaJenaGermany
| | - Jesús Vicente‐Carbajosa
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)–Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA/CSIC)Campus de MontegancedoPozuelo de Alarcón (Madrid)Spain
- Departamento de Biotecnología‐Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de BiosistemasUniversidad Politécnica de Madrid (UPM)MadridSpain
| | - Stephan Pollmann
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)–Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA/CSIC)Campus de MontegancedoPozuelo de Alarcón (Madrid)Spain
- Departamento de Biotecnología‐Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de BiosistemasUniversidad Politécnica de Madrid (UPM)MadridSpain
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2
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Lefoulon C. The bare necessities of plant K+ channel regulation. PLANT PHYSIOLOGY 2021; 187:2092-2109. [PMID: 34618033 PMCID: PMC8644596 DOI: 10.1093/plphys/kiab266] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 05/11/2021] [Indexed: 05/29/2023]
Abstract
Potassium (K+) channels serve a wide range of functions in plants from mineral nutrition and osmotic balance to turgor generation for cell expansion and guard cell aperture control. Plant K+ channels are members of the superfamily of voltage-dependent K+ channels, or Kv channels, that include the Shaker channels first identified in fruit flies (Drosophila melanogaster). Kv channels have been studied in depth over the past half century and are the best-known of the voltage-dependent channels in plants. Like the Kv channels of animals, the plant Kv channels are regulated over timescales of milliseconds by conformational mechanisms that are commonly referred to as gating. Many aspects of gating are now well established, but these channels still hold some secrets, especially when it comes to the control of gating. How this control is achieved is especially important, as it holds substantial prospects for solutions to plant breeding with improved growth and water use efficiencies. Resolution of the structure for the KAT1 K+ channel, the first channel from plants to be crystallized, shows that many previous assumptions about how the channels function need now to be revisited. Here, I strip the plant Kv channels bare to understand how they work, how they are gated by voltage and, in some cases, by K+ itself, and how the gating of these channels can be regulated by the binding with other protein partners. Each of these features of plant Kv channels has important implications for plant physiology.
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Affiliation(s)
- Cécile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow G12 8QQ, Scotland
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3
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Monder H, Maillard M, Chérel I, Zimmermann SD, Paris N, Cuéllar T, Gaillard I. Adjustment of K + Fluxes and Grapevine Defense in the Face of Climate Change. Int J Mol Sci 2021; 22:10398. [PMID: 34638737 PMCID: PMC8508874 DOI: 10.3390/ijms221910398] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/18/2021] [Accepted: 09/20/2021] [Indexed: 12/18/2022] Open
Abstract
Grapevine is one of the most economically important fruit crops due to the high value of its fruit and its importance in winemaking. The current decrease in grape berry quality and production can be seen as the consequence of various abiotic constraints imposed by climate changes. Specifically, produced wines have become too sweet, with a stronger impression of alcohol and fewer aromatic qualities. Potassium is known to play a major role in grapevine growth, as well as grape composition and wine quality. Importantly, potassium ions (K+) are involved in the initiation and maintenance of the berry loading process during ripening. Moreover, K+ has also been implicated in various defense mechanisms against abiotic stress. The first part of this review discusses the main negative consequences of the current climate, how they disturb the quality of grape berries at harvest and thus ultimately compromise the potential to obtain a great wine. In the second part, the essential electrical and osmotic functions of K+, which are intimately dependent on K+ transport systems, membrane energization, and cell K+ homeostasis, are presented. This knowledge will help to select crops that are better adapted to adverse environmental conditions.
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Affiliation(s)
- Houssein Monder
- BPMP, Univ Montpellier, CNRS, INRAE, Institut Agro, F-34060 Montpellier, France; (H.M.); (M.M.); (I.C.); (S.D.Z.); (N.P.)
| | - Morgan Maillard
- BPMP, Univ Montpellier, CNRS, INRAE, Institut Agro, F-34060 Montpellier, France; (H.M.); (M.M.); (I.C.); (S.D.Z.); (N.P.)
| | - Isabelle Chérel
- BPMP, Univ Montpellier, CNRS, INRAE, Institut Agro, F-34060 Montpellier, France; (H.M.); (M.M.); (I.C.); (S.D.Z.); (N.P.)
| | - Sabine Dagmar Zimmermann
- BPMP, Univ Montpellier, CNRS, INRAE, Institut Agro, F-34060 Montpellier, France; (H.M.); (M.M.); (I.C.); (S.D.Z.); (N.P.)
| | - Nadine Paris
- BPMP, Univ Montpellier, CNRS, INRAE, Institut Agro, F-34060 Montpellier, France; (H.M.); (M.M.); (I.C.); (S.D.Z.); (N.P.)
| | - Teresa Cuéllar
- CIRAD, UMR AGAP, Univ Montpellier, INRAE, Institut Agro, F-34398 Montpellier, France;
| | - Isabelle Gaillard
- BPMP, Univ Montpellier, CNRS, INRAE, Institut Agro, F-34060 Montpellier, France; (H.M.); (M.M.); (I.C.); (S.D.Z.); (N.P.)
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4
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Isolation and Functional Determination of SKOR Potassium Channel in Purple Osier Willow, Salix purpurea. Int J Genomics 2021; 2021:6669509. [PMID: 33708988 PMCID: PMC7932800 DOI: 10.1155/2021/6669509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 02/09/2021] [Accepted: 02/12/2021] [Indexed: 11/17/2022] Open
Abstract
Potassium (K+) plays key roles in plant growth and development. However, molecular mechanism studies of K+ nutrition in forest plants are largely rare. In plants, SKOR gene encodes for the outward rectifying Shaker-type K+ channel that is responsible for the long-distance transportation of K+ through xylem in roots. In this study, we determined a Shaker-type K+ channel gene in purple osier (Salix purpurea), designated as SpuSKOR, and determined its function using a patch clamp electrophysiological system. SpuSKOR was closely clustered with poplar PtrSKOR in the phylogenetic tree. Quantitative real-time PCR (qRT-PCR) analyses demonstrated that SpuSKOR was predominantly expressed in roots, and expression decreased under K+ depletion conditions. Patch clamp analysis via HEK293-T cells demonstrated that the activity of the SpuSKOR channel was activated when the cell membrane voltage reached at -10 mV, and the channel activity was enhanced along with the increase of membrane voltage. Outward currents were recorded and induced in response to the decrease of external K+ concentration. Our results indicate that SpuSKOR is a typical voltage dependent outwardly rectifying K+ channel in purple osier. This study provides theoretical basis for revealing the mechanism of K+ transport and distribution in woody plants.
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Jarratt-Barnham E, Wang L, Ning Y, Davies JM. The Complex Story of Plant Cyclic Nucleotide-Gated Channels. Int J Mol Sci 2021; 22:ijms22020874. [PMID: 33467208 PMCID: PMC7830781 DOI: 10.3390/ijms22020874] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 12/25/2022] Open
Abstract
Plant cyclic nucleotide-gated channels (CNGCs) are tetrameric cation channels which may be activated by the cyclic nucleotides (cNMPs) adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP). The genome of Arabidopsis thaliana encodes 20 CNGC subunits associated with aspects of development, stress response and immunity. Recently, it has been demonstrated that CNGC subunits form heterotetrameric complexes which behave differently from the homotetramers produced by their constituent subunits. These findings have widespread implications for future signalling research and may help explain how specificity can be achieved by CNGCs that are known to act in disparate pathways. Regulation of complex formation may involve cyclic nucleotide-gated channel-like proteins.
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6
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Dreyer I, Sussmilch FC, Fukushima K, Riadi G, Becker D, Schultz J, Hedrich R. How to Grow a Tree: Plant Voltage-Dependent Cation Channels in the Spotlight of Evolution. TRENDS IN PLANT SCIENCE 2021; 26:41-52. [PMID: 32868178 DOI: 10.1016/j.tplants.2020.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/21/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
Phylogenetic analysis can be a powerful tool for generating hypotheses regarding the evolution of physiological processes. Here, we provide an updated view of the evolution of the main cation channels in plant electrical signalling: the Shaker family of voltage-gated potassium channels and the two-pore cation (K+) channel (TPC1) family. Strikingly, the TPC1 family followed the same conservative evolutionary path as one particular subfamily of Shaker channels (Kout) and remained highly invariant after terrestrialisation, suggesting that electrical signalling was, and remains, key to survival on land. We note that phylogenetic analyses can have pitfalls, which may lead to erroneous conclusions. To avoid these in the future, we suggest guidelines for analyses of ion channel evolution in plants.
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Affiliation(s)
- Ingo Dreyer
- Center for Bioinformatics, Simulation and Modeling (CBSM), Faculty of Engineering, Universidad de Talca, 2 Norte 685, Talca, Chile.
| | - Frances C Sussmilch
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany; School of Natural Sciences, University of Tasmania, Hobart, TAS 7001, Australia
| | - Kenji Fukushima
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Gonzalo Riadi
- Center for Bioinformatics, Simulation and Modeling (CBSM), Faculty of Engineering, Universidad de Talca, 2 Norte 685, Talca, Chile
| | - Dirk Becker
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Jörg Schultz
- Department of Bioinformatics, Biozentrum, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany.
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7
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Garcia K, Guerrero-Galán C, Frank HER, Haider MZ, Delteil A, Conéjéro G, Lambilliotte R, Fizames C, Sentenac H, Zimmermann SD. Fungal Shaker-like channels beyond cellular K+ homeostasis: A role in ectomycorrhizal symbiosis between Hebeloma cylindrosporum and Pinus pinaster. PLoS One 2020; 15:e0242739. [PMID: 33216794 PMCID: PMC7678990 DOI: 10.1371/journal.pone.0242739] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 11/07/2020] [Indexed: 01/04/2023] Open
Abstract
Potassium (K+) acquisition, translocation and cellular homeostasis are mediated by various membrane transport systems in all organisms. We identified and described an ion channel in the ectomycorrhizal fungus Hebeloma cylindrosporum (HcSKC) that harbors features of animal voltage-dependent Shaker-like K+ channels, and investigated its role in both free-living hyphae and symbiotic conditions. RNAi lines affected in the expression of HcSKC were produced and used for in vitro mycorrhizal assays with the maritime pine as host plant, under standard or low K+ conditions. The adaptation of H. cylindrosporum to the downregulation of HcSKC was analyzed by qRT-PCR analyses for other K+-related transport proteins: the transporters HcTrk1, HcTrk2, and HcHAK, and the ion channels HcTOK1, HcTOK2.1, and HcTOK2.2. Downregulated HcSKC transformants displayed greater K+ contents at standard K+ only. In such conditions, plants inoculated with these transgenic lines were impaired in K+ nutrition. Taken together, these results support the hypothesis that the reduced expression of HcSKC modifies the pool of fungal K+ available for the plant and/or affects its symbiotic transfer to the roots. Our study reveals that the maintenance of K+ transport in H. cylindrosporum, through the regulation of HcSKC expression, is required for the K+ nutrition of the host plant.
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Affiliation(s)
- Kevin Garcia
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, California, United States of America
| | | | - Hannah E. R. Frank
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, California, United States of America
| | | | - Amandine Delteil
- BPMP, Université de Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France
| | - Geneviève Conéjéro
- BPMP, Université de Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France
- Plateforme Histocytologie et Imagerie Cellulaire Végétale, INRA-CIRAD Montpellier, France
| | - Raphaël Lambilliotte
- BPMP, Université de Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France
| | - Cécile Fizames
- BPMP, Université de Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France
| | - Hervé Sentenac
- BPMP, Université de Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France
| | - Sabine D. Zimmermann
- BPMP, Université de Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France
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8
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Adem GD, Chen G, Shabala L, Chen ZH, Shabala S. GORK Channel: A Master Switch of Plant Metabolism? TRENDS IN PLANT SCIENCE 2020; 25:434-445. [PMID: 31964604 DOI: 10.1016/j.tplants.2019.12.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/23/2019] [Accepted: 12/10/2019] [Indexed: 05/18/2023]
Abstract
Potassium regulates a plethora of metabolic and developmental response in plants, and upon exposure to biotic and abiotic stresses a substantial K+ loss occurs from plant cells. The outward-rectifying potassium efflux GORK channels are central to this stress-induced K+ loss from the cytosol. In the mammalian systems, signaling molecules such as gamma-aminobutyric acid, G-proteins, ATP, inositol, and protein phosphatases were shown to operate as ligands controlling many K+ efflux channels. Here we present the evidence that the same molecules may also regulate GORK channels in plants. This mechanism enables operation of the GORK channels as a master switch of the cell metabolism, thus adjusting intracellular K+ homeostasis to altered environmental conditions, to maximize plant adaptive potential.
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Affiliation(s)
- Getnet D Adem
- Tasmanian Institute for Agriculture, University of Tasmania, Hobart, TAS 7001, Australia
| | - Guang Chen
- Collaborative Innovation Centre for Grain Industry, College of Agriculture, Yangtze University, Jingzhou 434025, China; College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Lana Shabala
- Tasmanian Institute for Agriculture, University of Tasmania, Hobart, TAS 7001, Australia
| | - Zhong-Hua Chen
- School of Science and Health, Western Sydney University, Penrith, NSW 2751, Australia; Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia.
| | - Sergey Shabala
- Tasmanian Institute for Agriculture, University of Tasmania, Hobart, TAS 7001, Australia; International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China.
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9
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Villette J, Cuéllar T, Verdeil JL, Delrot S, Gaillard I. Grapevine Potassium Nutrition and Fruit Quality in the Context of Climate Change. FRONTIERS IN PLANT SCIENCE 2020; 11:123. [PMID: 32174933 PMCID: PMC7054452 DOI: 10.3389/fpls.2020.00123] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 01/28/2020] [Indexed: 06/01/2023]
Abstract
Potassium (K+) nutrition is of relevant interest for winegrowers because it influences grapevine growth, berry composition, as well as must and wine quality. Indeed, wine quality strongly depends on berry composition at harvest. However, K+ content of grape berries increased steadily over the last decades, in part due to climate change. Currently, the properties and qualities of many fruits are also impacted by environment. In grapevine, this disturbs berry properties resulting in unbalanced wines with poor organoleptic quality and low acidity. This requires a better understanding of the molecular basis of K+ accumulation and its control along grape berry development. This mini-review summarizes our current knowledge on K+ nutrition in relation with fruit quality in the context of a changing environment.
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Affiliation(s)
- Jérémy Villette
- BPMP, Univ Montpellier, CNRS, INRAE, SupAgro, Montpellier, France
| | - Teresa Cuéllar
- CIRAD, UMR AGAP, Univ Montpellier, INRA, Montpellier SupAgro, Montpellier, France
| | - Jean-Luc Verdeil
- CIRAD, UMR AGAP, Univ Montpellier, INRA, Montpellier SupAgro, Montpellier, France
| | - Serge Delrot
- EGFV, Bordeaux Sciences Agro, INRAE, Université de Bordeaux, ISVV, Villenave d’Ornon, France
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10
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Dreyer I, Vergara-Jaque A, Riedelsberger J, González W. Exploring the fundamental role of potassium channels in novel model plants. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:5985-5989. [PMID: 31738434 DOI: 10.1093/jxb/erz413] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This article comments on:Villette J, Cuéllar T, Zimmermann SD, Verdeil JL, Gaillard I. 2019. Unique features of the grapevine VvK5.1 channel support novel functions for outward K+ channels in plants. Journal of Experimental Botany 70, 6181–6193.
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Affiliation(s)
- Ingo Dreyer
- Centro de Bioinformática y Simulación Molecular (CBSM), Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Ariela Vergara-Jaque
- Centro de Bioinformática y Simulación Molecular (CBSM), Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Janin Riedelsberger
- Centro de Bioinformática y Simulación Molecular (CBSM), Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Wendy González
- Centro de Bioinformática y Simulación Molecular (CBSM), Facultad de Ingeniería, Universidad de Talca, Talca, Chile
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11
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Villette J, Cuéllar T, Zimmermann SD, Verdeil JL, Gaillard I. Unique features of the grapevine VvK5.1 channel support novel functions for outward K+ channels in plants. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:6181-6193. [PMID: 31327013 PMCID: PMC6859719 DOI: 10.1093/jxb/erz341] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 07/15/2019] [Indexed: 05/04/2023]
Abstract
Grapevine (Vitis vinifera L.), one of the most important fruit crops, is a model plant for studying the physiology of fleshy fruits. Here, we report on the characterization of a new grapevine Shaker-type K+ channel, VvK5.1. Phylogenetic analysis revealed that VvK5.1 belongs to the SKOR-like subfamily. Our functional characterization of VvK5.1 in Xenopus oocytes confirms that it is an outwardly rectifying K+ channel that displays strict K+ selectivity. Gene expression level analyses by real-time quantitative PCR showed that VvK5.1 expression was detected in berries, roots, and flowers. In contrast to its Arabidopsis thaliana counterpart that is involved in K+ secretion in the root pericycle, allowing root to shoot K+ translocation, VvK5.1 expression territory is greatly enlarged. Using in situ hybridization we showed that VvK5.1 is expressed in the phloem and perivascular cells of berries and in flower pistil. In the root, in addition to being expressed in the root pericycle like AtSKOR, a strong expression of VvK5.1 is detected in small cells facing the xylem that are involved in lateral root formation. This fine and selective expression pattern of VvK5.1 at the early stage of lateral root primordia supports a role for outward channels to switch on cell division initiation.
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Affiliation(s)
- Jérémy Villette
- BPMP, Université Montpellier, CNRS, INRA, SupAgro, Montpellier, France
| | - Teresa Cuéllar
- CIRAD, UMR AGAP, F-34398 Montpellier, France
- Université Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
| | | | - Jean-Luc Verdeil
- CIRAD, UMR AGAP, F-34398 Montpellier, France
- Université Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
| | - Isabelle Gaillard
- BPMP, Université Montpellier, CNRS, INRA, SupAgro, Montpellier, France
- Correspondence:
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12
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Riedelsberger J, Obando PA, Gonzalez W. Yeast strain Saccharomyces cerevisiae BYT45 lacking the cation extrusion systems ENA1-5 and NHA1 is suitable for the characterization of TASK-3 potassium channel antagonists. FEMS Yeast Res 2019; 19:5524363. [PMID: 31247642 DOI: 10.1093/femsyr/foz044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 06/24/2019] [Indexed: 11/13/2022] Open
Abstract
Finding new potential antagonists of potassium channels is a continuing task. TASK potassium channels operate over a large physiological range of membrane voltages, why they are thought to contribute to the excitability and resting potential of mammalian membrane potentials. Additionally, they are regulated by extracellular stimuli like changes in pH and K+ concentrations. TASK malfunctions are associated with diseases, which makes them popular targets for the search of new antagonists. Identification of channel inhibitors can be a time-consuming and expensive project. Here, we present an easy-to-use and inexpensive yeast system for the expression of the two-pore domain K+ channel TASK-3, and for the characterization of TASK-3 antagonists. The Saccharomyces cerevisiae strain BYT45 was used to express guinea pig TASK-3. The system allowed the expression and characterization of TASK-3 at variable pH values and K+ concentrations. Three known TASK-3 antagonists have been tested in the BYT45 yeast system: PK-THPP, ZnCl2 and Bupivacaine. Their inhibitory effect on TASK-3 was tested in solid and liquid media assays, and half maximal inhibitory concentrations were estimated. Although the system is less sensitive than more refined systems, the antagonistic activity could be confirmed for all three inhibitors.
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Affiliation(s)
- Janin Riedelsberger
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, 3460000 Talca, Chile
| | - Patricia A Obando
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, 3460000 Talca, Chile
| | - Wendy Gonzalez
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, 3460000 Talca, Chile.,Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Centro de Bioinformática y Simulación Molecular, Universidad de Talca, 2 Norte 685, 3460000 Talca, Chile
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13
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Locascio A, Andrés-Colás N, Mulet JM, Yenush L. Saccharomyces cerevisiae as a Tool to Investigate Plant Potassium and Sodium Transporters. Int J Mol Sci 2019; 20:E2133. [PMID: 31052176 PMCID: PMC6539216 DOI: 10.3390/ijms20092133] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 12/20/2022] Open
Abstract
Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On the other hand, sodium must be extruded from the plant or accumulated either in the vacuole or in specific plant structures. Maintaining a high intracellular K+/Na+ ratio under adverse environmental conditions or in the presence of salt is essential to maintain cellular homeostasis and to avoid toxicity. The baker's yeast, Saccharomyces cerevisiae, has been used to identify and characterize participants in potassium and sodium homeostasis in plants for many years. Its utility resides in the fact that the electric gradient across the membrane and the vacuoles is similar to plants. Most plant proteins can be expressed in yeast and are functional in this unicellular model system, which allows for productive structure-function studies for ion transporting proteins. Moreover, yeast can also be used as a high-throughput platform for the identification of genes that confer stress tolerance and for the study of protein-protein interactions. In this review, we summarize advances regarding potassium and sodium transport that have been discovered using the yeast model system, the state-of-the-art of the available techniques and the future directions and opportunities in this field.
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Affiliation(s)
- Antonella Locascio
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - Nuria Andrés-Colás
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - José Miguel Mulet
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - Lynne Yenush
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
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14
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Ragel P, Raddatz N, Leidi EO, Quintero FJ, Pardo JM. Regulation of K + Nutrition in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:281. [PMID: 30949187 PMCID: PMC6435592 DOI: 10.3389/fpls.2019.00281] [Citation(s) in RCA: 130] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 02/20/2019] [Indexed: 05/17/2023]
Abstract
Modern agriculture relies on mineral fertilization. Unlike other major macronutrients, potassium (K+) is not incorporated into organic matter but remains as soluble ion in the cell sap contributing up to 10% of the dry organic matter. Consequently, K+ constitutes a chief osmoticum to drive cellular expansion and organ movements, such as stomata aperture. Moreover, K+ transport is critical for the control of cytoplasmic and luminal pH in endosomes, regulation of membrane potential, and enzyme activity. Not surprisingly, plants have evolved a large ensemble of K+ transporters with defined functions in nutrient uptake by roots, storage in vacuoles, and ion translocation between tissues and organs. This review describes critical transport proteins governing K+ nutrition, their regulation, and coordinated activity, and summarizes our current understanding of signaling pathways activated by K+ starvation.
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Affiliation(s)
- Paula Ragel
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Seville, Spain
- Centre for Organismal Studies, Universität Heidelberg, Heidelberg, Germany
| | - Natalia Raddatz
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Seville, Spain
| | - Eduardo O. Leidi
- Instituto de Recursos Naturales y Agrobiologia de Sevilla, Consejo Superior de Investigaciones Cientificas, Seville, Spain
| | - Francisco J. Quintero
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Seville, Spain
| | - José M. Pardo
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Seville, Spain
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15
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Ragel P, Raddatz N, Leidi EO, Quintero FJ, Pardo JM. Regulation of K + Nutrition in Plants. FRONTIERS IN PLANT SCIENCE 2019. [PMID: 30949187 DOI: 10.3389/fpls.2019.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Modern agriculture relies on mineral fertilization. Unlike other major macronutrients, potassium (K+) is not incorporated into organic matter but remains as soluble ion in the cell sap contributing up to 10% of the dry organic matter. Consequently, K+ constitutes a chief osmoticum to drive cellular expansion and organ movements, such as stomata aperture. Moreover, K+ transport is critical for the control of cytoplasmic and luminal pH in endosomes, regulation of membrane potential, and enzyme activity. Not surprisingly, plants have evolved a large ensemble of K+ transporters with defined functions in nutrient uptake by roots, storage in vacuoles, and ion translocation between tissues and organs. This review describes critical transport proteins governing K+ nutrition, their regulation, and coordinated activity, and summarizes our current understanding of signaling pathways activated by K+ starvation.
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Affiliation(s)
- Paula Ragel
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Seville, Spain
- Centre for Organismal Studies, Universität Heidelberg, Heidelberg, Germany
| | - Natalia Raddatz
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Seville, Spain
| | - Eduardo O Leidi
- Instituto de Recursos Naturales y Agrobiologia de Sevilla, Consejo Superior de Investigaciones Cientificas, Seville, Spain
| | - Francisco J Quintero
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Seville, Spain
| | - José M Pardo
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Seville, Spain
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16
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van Kleeff PJM, Gao J, Mol S, Zwart N, Zhang H, Li KW, de Boer AH. The Arabidopsis GORK K +-channel is phosphorylated by calcium-dependent protein kinase 21 (CPK21), which in turn is activated by 14-3-3 proteins. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2018; 125:219-231. [PMID: 29475088 DOI: 10.1016/j.plaphy.2018.02.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 02/11/2018] [Accepted: 02/13/2018] [Indexed: 05/23/2023]
Abstract
Potassium (K+) is a vital ion for many processes in the plant and fine-tuned ion channels control the K+-fluxes across the plasma membrane. GORK is an outward-rectifying K+-channel with important functions in stomatal closure and in root K+-homeostasis. In this study, post-translational modification of the Arabidopsis GORK ion channel and its regulation by 14-3-3 proteins was investigated. To investigate the possible interaction between GORK and 14-3-3s an in vivo pull-down from an Arabidopsis protein extract with recombinant GORK C-terminus (GORK-C) indeed identified endogenous 14-3-3s (LAMBDA, CHI, NU) as binding partners in a phosphorylation dependent manner. However, a direct interaction between 14-3-3's and GORK-C could not be demonstrated. Since the pull-down of 14-3-3s was phosphorylation dependent, we determined GORK-C as substrate for CPK21 phosphorylation and identified three CPK21 phospho-sites in the GORK protein (T344, S518 and S649). Moreover, interaction of 14-3-3 to CPK21 strongly stimulates its kinase activity; an effect that can result in increased GORK phosphorylation and change in activity. Using the non-invasive vibrating probe technique, we measured the predominantly GORK mediated salt induced K+-efflux from wild-type, gork, cpk21, aha2 and 14-3-3 mutant roots. The mutants cpk21 and aha2 did not show statistical significant differences compared to WT. However, two (out of six) 14-3-3 isoforms, CHI and PHI, have a clear function in the salt induced K+-efflux. In conclusion, our results show that GORK can be phosphorylated by CPK21 and suggest that 14-3-3 proteins control GORK activity through binding with and activation of CPK21.
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Affiliation(s)
- P J M van Kleeff
- Department of Structural Biology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
| | - J Gao
- Department of Structural Biology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
| | - S Mol
- Department of Structural Biology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
| | - N Zwart
- Department of Structural Biology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
| | - H Zhang
- Netherlands Proteomics Centre, Utrecht University - H.R. Kruyt gebouw, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
| | - K W Li
- Department of Molecular and Cellular Neurobiology, Faculty of Earth and Life Sciences, Center for Neurogenomics and Cognitive Research, Neuroscience Campus, Amsterdam, The Netherlands.
| | - A H de Boer
- Department of Structural Biology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
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17
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Alaimo A, Nuñez E, Aivar P, Fernández-Orth J, Gomis-Perez C, Bernardo-Seisdedos G, Malo C, Villarroel A. Calmodulin confers calcium sensitivity to the stability of the distal intracellular assembly domain of Kv7.2 channels. Sci Rep 2017; 7:13425. [PMID: 29044210 PMCID: PMC5647379 DOI: 10.1038/s41598-017-13811-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 09/29/2017] [Indexed: 01/03/2023] Open
Abstract
Tetrameric coiled-coil structures are present in many ion channels, often adjacent to a calmodulin (CaM) binding site, although the relationship between the two is not completely understood. Here we examine the dynamic properties of the ABCD domain located in the intracellular C-terminus of tetrameric, voltage-dependent, potassium selective Kv7.2 channels. This domain encompasses the CaM binding site formed by helices A and B, followed by helix C, which is linked to the helix D coiled-coil. The data reveals that helix D stabilizes CaM binding, promoting trans-binding (CaM embracing neighboring subunits), and they suggest that the ABCD domain can be exchanged between subunits of the tetramer. Exchange is faster when mutations in AB weaken the CaM interaction. The exchange of ABCD domains is slower in the presence of Ca2+, indicating that CaM stabilization of the tetrameric assembly is enhanced when loaded with this cation. Our observations are consistent with a model that involves a dynamic mechanism of helix D assembly, which supports reciprocal allosteric coupling between the A-B module and the coiled-coil formed by the helix D. Thus, formation of the distal helix D tetramer influences CaM binding and CaM-dependent Kv7.2 properties, whereas reciprocally, CaM and Ca2+ influence the dynamic behavior of the helix D coiled-coil.
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Affiliation(s)
- Alessandro Alaimo
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Eider Nuñez
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Paloma Aivar
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Juncal Fernández-Orth
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Carolina Gomis-Perez
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Ganeko Bernardo-Seisdedos
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Covadonga Malo
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Alvaro Villarroel
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain.
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18
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Saito S, Hoshi N, Zulkifli L, Widyastuti S, Goshima S, Dreyer I, Uozumi N. Identification of regions responsible for the function of the plant K + channels KAT1 and AKT2 in Saccharomyces cerevisiae and Xenopus laevis oocytes. Channels (Austin) 2017; 11:510-516. [PMID: 28933647 DOI: 10.1080/19336950.2017.1372066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Arabidopsis K+ channel KAT1 complements in K+-limited medium the growth of the K+ uptake defective Saccharomyces cerevisiae mutant strain CY162, while another K+ 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+-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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Affiliation(s)
- Shunya Saito
- a Department of Biomolecular Engineering , Graduate School of Engineering, Tohoku University , Sendai , Japan
| | - Naomi Hoshi
- a Department of Biomolecular Engineering , Graduate School of Engineering, Tohoku University , Sendai , Japan
| | - Lalu Zulkifli
- a Department of Biomolecular Engineering , Graduate School of Engineering, Tohoku University , Sendai , Japan
| | - Sri Widyastuti
- b Bioscience and Biotechnology Center , Nagoya University , Nagoya , Japan
| | - Shinobu Goshima
- b Bioscience and Biotechnology Center , Nagoya University , Nagoya , Japan
| | - Ingo Dreyer
- c Centro de Bioinformática y Simulación Molecular , Facultad de Ingeniería, Universidad de Talca , Talca , Chile
| | - Nobuyuki Uozumi
- a Department of Biomolecular Engineering , Graduate School of Engineering, Tohoku University , Sendai , Japan
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19
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Sklodowski K, Riedelsberger J, Raddatz N, Riadi G, Caballero J, Chérel I, Schulze W, Graf A, Dreyer I. The receptor-like pseudokinase MRH1 interacts with the voltage-gated potassium channel AKT2. Sci Rep 2017; 7:44611. [PMID: 28300158 PMCID: PMC5353636 DOI: 10.1038/srep44611] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 01/25/2017] [Indexed: 12/23/2022] Open
Abstract
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.
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Affiliation(s)
- Kamil Sklodowski
- Heisenberg Group of Biophysics and Molecular Plant Biology, Institute of Biochemistry and Biology, Molecular Biology, University of Potsdam, D-14476 Potsdam-Golm, Germany
- Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany
- ETH Zürich, Department of Biology, CH-8092 Zürich, Switzerland
| | - Janin Riedelsberger
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Natalia Raddatz
- Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), E-28223 Pozuelo de Alarcón (Madrid), Spain
- Instituto de Biología Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas, E-41092 Sevilla, Spain
| | - Gonzalo Riadi
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Julio Caballero
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Isabelle Chérel
- Biochimie et Physiologie Moléculaire des Plantes, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5004, Institut National de la Recherche Agronomique U386, Montpellier SupAgro, Université Montpellier II, F-34060 Montpellier cedex 2, France
| | - Waltraud Schulze
- Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany
- Department of Plant Systems Biology, University of Hohenheim, D-70593 Stuttgart, Germany
| | - Alexander Graf
- Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany
| | - Ingo Dreyer
- Heisenberg Group of Biophysics and Molecular Plant Biology, Institute of Biochemistry and Biology, Molecular Biology, University of Potsdam, D-14476 Potsdam-Golm, Germany
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
- Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), E-28223 Pozuelo de Alarcón (Madrid), Spain
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20
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Garriga M, Raddatz N, Véry AA, Sentenac H, Rubio-Meléndez ME, González W, Dreyer I. Cloning and functional characterization of HKT1 and AKT1 genes of Fragaria spp.-Relationship to plant response to salt stress. JOURNAL OF PLANT PHYSIOLOGY 2017; 210:9-17. [PMID: 28039842 DOI: 10.1016/j.jplph.2016.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 12/08/2016] [Accepted: 12/11/2016] [Indexed: 05/03/2023]
Abstract
Commercial strawberry, Fragaria x ananassa Duch., is a species sensitive to salinity. Under saline conditions, Na+ uptake by the plant is increased, while K+ uptake is significantly reduced. Maintaining an adequate K+/Na+ cytosolic ratio determines the ability of the plant to survive in saline environments. The goal of the present work was to clone and functionally characterize the genes AKT1 and HKT1 involved in K+ and Na+ transport in strawberry and to determine the relationship of these genes with the responses of three Fragaria spp. genotypes having different ecological adaptations to salt stress. FaHKT1 and FcHKT1 proteins from F. x ananassa and F. chiloensis have 98.1% of identity, while FaAKT1 and FcAKT1 identity is 99.7%. FaHKT1 and FaAKT1 from F. x ananassa, were functionally characterized in Xenopus oocytes. FaHKT1, belongs to the group I of HKT transporters and is selective for Na+. Expression of FaAKT1 in oocytes showed that the protein is a typical inward-rectifying and highly K+-selective channel. The relative expression of Fragaria HKT1 and AKT1 genes was studied in roots of F. x ananassa cv. Camarosa and of F. chiloensis (accessions Bau and Cucao) grown under salt stress. The expression of AKT1 was transiently increased in 'Camarosa', decreased in 'Cucao' and was not affected in 'Bau' upon salt stress. HKT1 expression was significantly increased in roots of 'Cucao' and was not affected in the other two genotypes. The increased relative expression of HKT1 and decreased expression of AKT1 in 'Cucao' roots correlates with the higher tolerance to salinity of this genotype in comparison with 'Camarosa' and 'Bau'.
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Affiliation(s)
- Miguel Garriga
- Facultad de Ciencias Agrarias, Universidad de Talca, Casilla 747, Talca, Chile.
| | - Natalia Raddatz
- Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), E-28223 Pozuelo de Alarcón, Madrid, Spain
| | - Anne-Aliénor Véry
- Biochimie et Physiologie Moléculaire des Plantes, UMR 5004, ENSA.M INRA CNRS UMII, 34060 Montpellier, Cedex 2, France
| | - Hervé Sentenac
- Biochimie et Physiologie Moléculaire des Plantes, UMR 5004, ENSA.M INRA CNRS UMII, 34060 Montpellier, Cedex 2, France
| | - María E Rubio-Meléndez
- Facultad de Ciencias Agrarias, Universidad de Talca, Casilla 747, Talca, Chile; Instituto de Ciencias Biológicas, Universidad de Talca, Casilla 747, Talca, Chile
| | - Wendy González
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Casilla 721, Talca, Chile
| | - Ingo Dreyer
- Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), E-28223 Pozuelo de Alarcón, Madrid, Spain; Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Casilla 721, Talca, Chile.
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21
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Zhang A, Ren HM, Tan YQ, Qi GN, Yao FY, Wu GL, Yang LW, Hussain J, Sun SJ, Wang YF. S-type Anion Channels SLAC1 and SLAH3 Function as Essential Negative Regulators of Inward K+ Channels and Stomatal Opening in Arabidopsis. THE PLANT CELL 2016. [PMID: 27002025 PMCID: PMC4863386 DOI: 10.1105/tpc.15.01050] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Drought stress induces stomatal closure and inhibits stomatal opening simultaneously. However, the underlying molecular mechanism is still largely unknown. Here we show that S-type anion channels SLAC1 and SLAH3 mainly inhibit inward K+ (K+in) channel KAT1 by protein-protein interaction, and consequently prevent stomatal opening in Arabidopsis. Voltage-clamp results demonstrated that SLAC1 inhibited KAT1 dramatically, but did not inhibit KAT2. SLAH3 inhibited KAT1 to a weaker degree relative to SLAC1. Both the N terminus and the C terminuses of SLAC1 inhibited KAT1, but the inhibition by the N terminus was stronger. The C terminus was essential for the inhibition of KAT1 by SLAC1. Furthermore, drought stress strongly up-regulated the expression of SLAC1 and SLAH3 in Arabidopsis guard cells, and the over-expression of wild type and truncated SLAC1 dramatically impaired K+in currents of guard cells and light-induced stomatal opening. Additionally, the inhibition of KAT1 by SLAC1 and KC1 only partially overlapped, suggesting that SLAC1 and KC1 inhibited K+in channels using different molecular mechanisms. Taken together, we discovered a novel regulatory mechanism for stomatal movement, in which singling pathways for stomatal closure and opening are directly coupled together by protein-protein interaction between SLAC1/SLAH3 and KAT1 in Arabidopsis.
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Affiliation(s)
- An Zhang
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Hui-Min Ren
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghaic China [CN]
| | - Yan-Qiu Tan
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghaic China [CN]
| | - Guo-Ning Qi
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Fen-Yong Yao
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Gui-Li Wu
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Lu-Wen Yang
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Jamshaid Hussain
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Shu-Jing Sun
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Yong-Fei Wang
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai POSTAL_CODE: 200032 China [CN]
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22
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Zhang A, Ren HM, Tan YQ, Qi GN, Yao FY, Wu GL, Yang LW, Hussain J, Sun SJ, Wang YF. S-type Anion Channels SLAC1 and SLAH3 Function as Essential Negative Regulators of Inward K+ Channels and Stomatal Opening in Arabidopsis. THE PLANT CELL 2016; 28:949-955. [PMID: 27002025 PMCID: PMC4863386 DOI: 10.1105/tpc.16.01050] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 02/22/2016] [Accepted: 03/17/2016] [Indexed: 05/08/2023]
Abstract
Drought stress induces stomatal closure and inhibits stomatal opening simultaneously. However, the underlying molecular mechanism is still largely unknown. Here we show that S-type anion channels SLAC1 and SLAH3 mainly inhibit inward K+ (K+in) channel KAT1 by protein-protein interaction, and consequently prevent stomatal opening in Arabidopsis. Voltage-clamp results demonstrated that SLAC1 inhibited KAT1 dramatically, but did not inhibit KAT2. SLAH3 inhibited KAT1 to a weaker degree relative to SLAC1. Both the N terminus and the C terminuses of SLAC1 inhibited KAT1, but the inhibition by the N terminus was stronger. The C terminus was essential for the inhibition of KAT1 by SLAC1. Furthermore, drought stress strongly up-regulated the expression of SLAC1 and SLAH3 in Arabidopsis guard cells, and the over-expression of wild type and truncated SLAC1 dramatically impaired K+in currents of guard cells and light-induced stomatal opening. Additionally, the inhibition of KAT1 by SLAC1 and KC1 only partially overlapped, suggesting that SLAC1 and KC1 inhibited K+in channels using different molecular mechanisms. Taken together, we discovered a novel regulatory mechanism for stomatal movement, in which singling pathways for stomatal closure and opening are directly coupled together by protein-protein interaction between SLAC1/SLAH3 and KAT1 in Arabidopsis.
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Affiliation(s)
- An Zhang
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Hui-Min Ren
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghaic China [CN]
| | - Yan-Qiu Tan
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghaic China [CN]
| | - Guo-Ning Qi
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Fen-Yong Yao
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Gui-Li Wu
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Lu-Wen Yang
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Jamshaid Hussain
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Shu-Jing Sun
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai China [CN]
| | - Yong-Fei Wang
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences CITY: Shanghai STATE: Shanghai POSTAL_CODE: 200032 China [CN]
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23
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Drechsler N, Zheng Y, Bohner A, Nobmann B, von Wirén N, Kunze R, Rausch C. Nitrate-Dependent Control of Shoot K Homeostasis by the Nitrate Transporter1/Peptide Transporter Family Member NPF7.3/NRT1.5 and the Stelar K+ Outward Rectifier SKOR in Arabidopsis. PLANT PHYSIOLOGY 2015; 169:2832-47. [PMID: 26508776 PMCID: PMC4677904 DOI: 10.1104/pp.15.01152] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/25/2015] [Indexed: 05/03/2023]
Abstract
Root-to-shoot translocation and shoot homeostasis of potassium (K) determine nutrient balance, growth, and stress tolerance of vascular plants. To maintain the cation-anion balance, xylem loading of K(+) in the roots relies on the concomitant loading of counteranions, like nitrate (NO3 (-)). However, the coregulation of these loading steps is unclear. Here, we show that the bidirectional, low-affinity Nitrate Transporter1 (NRT1)/Peptide Transporter (PTR) family member NPF7.3/NRT1.5 is important for the NO3 (-)-dependent K(+) translocation in Arabidopsis (Arabidopsis thaliana). Lack of NPF7.3/NRT1.5 resulted in K deficiency in shoots under low NO3 (-) nutrition, whereas the root elemental composition was unchanged. Gene expression data corroborated K deficiency in the nrt1.5-5 shoot, whereas the root responded with a differential expression of genes involved in cation-anion balance. A grafting experiment confirmed that the presence of NPF7.3/NRT1.5 in the root is a prerequisite for proper root-to-shoot translocation of K(+) under low NO3 (-) supply. Because the depolarization-activated Stelar K(+) Outward Rectifier (SKOR) has previously been described as a major contributor for root-to-shoot translocation of K(+) in Arabidopsis, we addressed the hypothesis that NPF7.3/NRT1.5-mediated NO3 (-) translocation might affect xylem loading and root-to-shoot K(+) translocation through SKOR. Indeed, growth of nrt1.5-5 and skor-2 single and double mutants under different K/NO3 (-) regimes revealed that both proteins contribute to K(+) translocation from root to shoot. SKOR activity dominates under high NO3 (-) and low K(+) supply, whereas NPF7.3/NRT1.5 is required under low NO3 (-) availability. This study unravels nutritional conditions as a critical factor for the joint activity of SKOR and NPF7.3/NRT1.5 for shoot K homeostasis.
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Affiliation(s)
- Navina Drechsler
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.)
| | - Yue Zheng
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.)
| | - Anne Bohner
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.)
| | - Barbara Nobmann
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.)
| | - Nicolaus von Wirén
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.)
| | - Reinhard Kunze
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.)
| | - Christine Rausch
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.)
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24
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Lin TF, Lin IW, Chen SC, Wu HH, Yang CS, Fang HY, Chiu MM, Jeng CJ. The subfamily-specific assembly of Eag and Erg K+ channels is determined by both the amino and the carboxyl recognition domains. J Biol Chem 2014; 289:22815-22834. [PMID: 25008323 DOI: 10.1074/jbc.m114.574814] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A functional voltage-gated K(+) (Kv) channel comprises four pore-forming α-subunits, and only members of the same Kv channel subfamily may co-assemble to form heterotetramers. The ether-à-go-go family of Kv channels (KCNH) encompasses three distinct subfamilies: Eag (Kv10), Erg (Kv11), and Elk (Kv12). Members of different ether-à-go-go subfamilies, such as Eag and Erg, fail to form heterotetramers. Although a short stretch of amino acid sequences in the distal C-terminal section has been implicated in subfamily-specific subunit assembly, it remains unclear whether this region serves as the sole and/or principal subfamily recognition domain for Eag and Erg. Here we aim to ascertain the structural basis underlying the subfamily specificity of ether-à-go-go channels by generating various chimeric constructs between rat Eag1 and human Erg subunits. Biochemical and electrophysiological characterizations of the subunit interaction properties of a series of different chimeric and truncation constructs over the C terminus suggested that the putative C-terminal recognition domain is dispensable for subfamily-specific assembly. Further chimeric analyses over the N terminus revealed that the N-terminal region may also harbor a subfamily recognition domain. Importantly, exchanging either the N-terminal or the C-terminal domain alone led to a virtual loss of the intersubfamily assembly boundary. By contrast, simultaneously swapping both recognition domains resulted in a reversal of subfamily specificity. Our observations are consistent with the notion that both the N-terminal and the C-terminal recognition domains are required to sustain the subfamily-specific assembly of rat Eag1 and human Erg.
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Affiliation(s)
- Ting-Feng Lin
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - I-Wen Lin
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Shu-Ching Chen
- Department of Medical Research, National Taiwan University Hospital, Taipei 10051, Taiwan
| | - Hao-Han Wu
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Chi-Sheng Yang
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Hsin-Yu Fang
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Mei-Miao Chiu
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Chung-Jiuan Jeng
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan; Brain Research Center, National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan and.
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25
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Véry AA, Nieves-Cordones M, Daly M, Khan I, Fizames C, Sentenac H. Molecular biology of K+ transport across the plant cell membrane: what do we learn from comparison between plant species? JOURNAL OF PLANT PHYSIOLOGY 2014; 171:748-69. [PMID: 24666983 DOI: 10.1016/j.jplph.2014.01.011] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 01/30/2014] [Indexed: 05/20/2023]
Abstract
Cloning and characterizations of plant K(+) transport systems aside from Arabidopsis have been increasing over the past decade, favored by the availability of more and more plant genome sequences. Information now available enables the comparison of some of these systems between species. In this review, we focus on three families of plant K(+) transport systems that are active at the plasma membrane: the Shaker K(+) channel family, comprised of voltage-gated channels that dominate the plasma membrane conductance to K(+) in most environmental conditions, and two families of transporters, the HAK/KUP/KT K(+) transporter family, which includes some high-affinity transporters, and the HKT K(+) and/or Na(+) transporter family, in which K(+)-permeable members seem to be present in monocots only. The three families are briefly described, giving insights into the structure of their members and on functional properties and their roles in Arabidopsis or rice. The structure of the three families is then compared between plant species through phylogenic analyses. Within clusters of ortologues/paralogues, similarities and differences in terms of expression pattern, functional properties and, when known, regulatory interacting partners, are highlighted. The question of the physiological significance of highlighted differences is also addressed.
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Affiliation(s)
- Anne-Aliénor Véry
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France.
| | - Manuel Nieves-Cordones
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France
| | - Meriem Daly
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France; Laboratoire d'Ecologie et d'Environnement, Faculté des Sciences Ben M'sik, Université Hassan II-Mohammedia, Avenue Cdt Driss El Harti, BP 7955, Sidi Othmane, Casablanca, Morocco
| | - Imran Khan
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France; Department of Agronomy, University of Agriculture, Faisalabad, Pakistan
| | - Cécile Fizames
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France
| | - Hervé Sentenac
- Biochimie & Physiologie Moléculaire des Plantes, UMR 5004 CNRS/386 INRA/SupAgro Montpellier/Université Montpellier 2, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France
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26
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Anschütz U, Becker D, Shabala S. Going beyond nutrition: regulation of potassium homoeostasis as a common denominator of plant adaptive responses to environment. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:670-87. [PMID: 24635902 DOI: 10.1016/j.jplph.2014.01.009] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 01/14/2014] [Accepted: 01/17/2014] [Indexed: 05/18/2023]
Abstract
Partially and fully completed plant genome sequencing projects in both lower and higher plants allow drawing a comprehensive picture of the molecular and structural diversities of plant potassium transporter genes and their encoded proteins. While the early focus of the research in this field was aimed on the structure-function studies and understanding of the molecular mechanisms underlying K(+) transport, availability of Arabidopsis thaliana mutant collections in combination with micro-array techniques have significantly advanced our understanding of K(+) channel physiology, providing novel insights into the transcriptional regulation of potassium homeostasis in plants. More recently, posttranslational regulation of potassium transport systems has moved into the center stage of potassium transport research. The current review is focused on the most exciting developments in this field. By summarizing recent work on potassium transporter regulation we show that potassium transport in general, and potassium channels in particular, represent important targets and are mediators of the cellular responses during different developmental stages in a plant's life cycle. We show that regulation of intracellular K(+) homeostasis is essential to mediate plant adaptive responses to a broad range of abiotic and biotic stresses including drought, salinity, and oxidative stress. We further link post-translational regulation of K(+) channels with programmed cell death and show that K(+) plays a critical role in controlling the latter process. Thus, is appears that K(+) is not just the essential nutrient required to support optimal plant growth and yield but is also an important signaling agent mediating a wide range of plant adaptive responses to environment.
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Affiliation(s)
- Uta Anschütz
- University of Wuerzburg, Plant Molecular Biology & Biophysics, Wuerzburg, Germany
| | - Dirk Becker
- University of Wuerzburg, Plant Molecular Biology & Biophysics, Wuerzburg, Germany.
| | - Sergey Shabala
- School of Agricultural Science, University of Tasmania, Hobart, Australia
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27
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Adem GD, Roy SJ, Zhou M, Bowman JP, Shabala S. Evaluating contribution of ionic, osmotic and oxidative stress components towards salinity tolerance in barley. BMC PLANT BIOLOGY 2014; 14:113. [PMID: 24774965 PMCID: PMC4021550 DOI: 10.1186/1471-2229-14-113] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 04/24/2014] [Indexed: 05/18/2023]
Abstract
BACKGROUND Salinity tolerance is a physiologically multi-faceted trait attributed to multiple mechanisms. Three barley (Hordeum vulgare) varieties contrasting in their salinity tolerance were used to assess the relative contribution of ionic, osmotic and oxidative stress components towards overall salinity stress tolerance in this species, both at the whole-plant and cellular levels. In addition, transcriptional changes in the gene expression profile were studied for key genes mediating plant ionic and oxidative homeostasis (NHX; RBOH; SOD; AHA and GORK), to compare a contribution of transcriptional and post-translational factors towards the specific components of salinity tolerance. RESULTS Our major findings are two-fold. First, plant tissue tolerance was a dominating component that has determined the overall plant responses to salinity, with root K(+) retention ability and reduced sensitivity to stress-induced hydroxyl radical production being the main contributing tolerance mechanisms. Second, it was not possible to infer which cultivars were salinity tolerant based solely on expression profiling of candidate genes at one specific time point. For the genes studied and the time point selected that transcriptional changes in the expression of these specific genes had a small role for barley's adaptive responses to salinity. CONCLUSIONS For better tissue tolerance, sodium sequestration, K(+) retention and resistance to oxidative stress all appeared to be crucial. Because these traits are highly interrelated, it is suggested that a major progress in crop breeding for salinity tolerance can be achieved only if these complementary traits are targeted at the same time. This study also highlights the essentiality of post translational modifications in plant adaptive responses to salinity.
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Affiliation(s)
- Getnet Dino Adem
- School of Land and Food, University of Tasmania, Private Bag 54, Hobart Tas 7001, Australia
| | - Stuart J Roy
- Australian Centre for Plant Functional Genomics, Private Mail Bag 1, Glen Osmond SA 5064, Australia
- University of Adelaide, Private Mail Bag 1, Glen Osmond SA 5064, Australia
| | - Meixue Zhou
- School of Land and Food, University of Tasmania, Private Bag 54, Hobart Tas 7001, Australia
| | - John P Bowman
- School of Land and Food, University of Tasmania, Private Bag 54, Hobart Tas 7001, Australia
| | - Sergey Shabala
- School of Land and Food, University of Tasmania, Private Bag 54, Hobart Tas 7001, Australia
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28
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Nieves-Cordones M, Chavanieu A, Jeanguenin L, Alcon C, Szponarski W, Estaran S, Chérel I, Zimmermann S, Sentenac H, Gaillard I. Distinct amino acids in the C-linker domain of the Arabidopsis K+ channel KAT2 determine its subcellular localization and activity at the plasma membrane. PLANT PHYSIOLOGY 2014; 164:1415-29. [PMID: 24406792 PMCID: PMC3938630 DOI: 10.1104/pp.113.229757] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/05/2014] [Indexed: 05/18/2023]
Abstract
Shaker K(+) channels form the major K(+) conductance of the plasma membrane in plants. They are composed of four subunits arranged around a central ion-conducting pore. The intracellular carboxy-terminal region of each subunit contains several regulatory elements, including a C-linker region and a cyclic nucleotide-binding domain (CNBD). The C-linker is the first domain present downstream of the sixth transmembrane segment and connects the CNBD to the transmembrane core. With the aim of identifying the role of the C-linker in the Shaker channel properties, we performed subdomain swapping between the C-linker of two Arabidopsis (Arabidopsis thaliana) Shaker subunits, K(+) channel in Arabidopsis thaliana2 (KAT2) and Arabidopsis thaliana K(+) rectifying channel1 (AtKC1). These two subunits contribute to K(+) transport in planta by forming heteromeric channels with other Shaker subunits. However, they display contrasting behavior when expressed in tobacco mesophyll protoplasts: KAT2 forms homotetrameric channels active at the plasma membrane, whereas AtKC1 is retained in the endoplasmic reticulum when expressed alone. The resulting chimeric/mutated constructs were analyzed for subcellular localization and functionally characterized. We identified two contiguous amino acids, valine-381 and serine-382, located in the C-linker carboxy-terminal end, which prevent KAT2 surface expression when mutated into the equivalent residues from AtKC1. Moreover, we demonstrated that the nine-amino acid stretch 312TVRAASEFA320 that composes the first C-linker α-helix located just below the pore is a crucial determinant of KAT2 channel activity. A KAT2 C-linker/CNBD three-dimensional model, based on animal HCN (for Hyperpolarization-activated, cyclic nucleotide-gated K(+)) channels as structure templates, has been built and used to discuss the role of the C-linker in plant Shaker inward channel structure and function.
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Affiliation(s)
- Manuel Nieves-Cordones
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier cedex 2, France (M.N.-C., L.J., C.A., W.S., I.C., S.Z., H.S., I.G.); and
- Institut des Biomolécules Max Mousseron, Unité Mixte de Recherche 5247, Faculté de Pharmacie, 34093 Montpellier cedex, France (A.C., S.E.)
| | - Alain Chavanieu
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier cedex 2, France (M.N.-C., L.J., C.A., W.S., I.C., S.Z., H.S., I.G.); and
- Institut des Biomolécules Max Mousseron, Unité Mixte de Recherche 5247, Faculté de Pharmacie, 34093 Montpellier cedex, France (A.C., S.E.)
| | | | - Carine Alcon
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier cedex 2, France (M.N.-C., L.J., C.A., W.S., I.C., S.Z., H.S., I.G.); and
- Institut des Biomolécules Max Mousseron, Unité Mixte de Recherche 5247, Faculté de Pharmacie, 34093 Montpellier cedex, France (A.C., S.E.)
| | - Wojciech Szponarski
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier cedex 2, France (M.N.-C., L.J., C.A., W.S., I.C., S.Z., H.S., I.G.); and
- Institut des Biomolécules Max Mousseron, Unité Mixte de Recherche 5247, Faculté de Pharmacie, 34093 Montpellier cedex, France (A.C., S.E.)
| | - Sebastien Estaran
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier cedex 2, France (M.N.-C., L.J., C.A., W.S., I.C., S.Z., H.S., I.G.); and
- Institut des Biomolécules Max Mousseron, Unité Mixte de Recherche 5247, Faculté de Pharmacie, 34093 Montpellier cedex, France (A.C., S.E.)
| | - Isabelle Chérel
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier cedex 2, France (M.N.-C., L.J., C.A., W.S., I.C., S.Z., H.S., I.G.); and
- Institut des Biomolécules Max Mousseron, Unité Mixte de Recherche 5247, Faculté de Pharmacie, 34093 Montpellier cedex, France (A.C., S.E.)
| | - Sabine Zimmermann
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier cedex 2, France (M.N.-C., L.J., C.A., W.S., I.C., S.Z., H.S., I.G.); and
- Institut des Biomolécules Max Mousseron, Unité Mixte de Recherche 5247, Faculté de Pharmacie, 34093 Montpellier cedex, France (A.C., S.E.)
| | - Hervé Sentenac
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier cedex 2, France (M.N.-C., L.J., C.A., W.S., I.C., S.Z., H.S., I.G.); and
- Institut des Biomolécules Max Mousseron, Unité Mixte de Recherche 5247, Faculté de Pharmacie, 34093 Montpellier cedex, France (A.C., S.E.)
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Nieves-Cordones M, Gaillard I. Involvement of the S4-S5 linker and the C-linker domain regions to voltage-gating in plant Shaker channels: comparison with animal HCN and Kv channels. PLANT SIGNALING & BEHAVIOR 2014; 9:e972892. [PMID: 25482770 PMCID: PMC4622754 DOI: 10.4161/15592316.2014.972892] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Among the different transport systems present in plant cells, Shaker channels constitute the major pathway for K(+) in the plasma membrane. Plant Shaker channels are members of the 6 transmembrane-1 pore (6TM-1P) cation channel superfamily as the animal Shaker (Kv) and HCN channels. All these channels are voltage-gated K(+) channels: Kv channels are outward-rectifiers, opened at depolarized voltages and HCN channels are inward-rectifiers, opened by membrane hyperpolarization. Among plant Shaker channels, we can find outward-rectifiers, inward-rectifiers and also weak-rectifiers, with weak voltage dependence. Despite the absence of crystal structures of plant Shaker channels, functional analyses coupled to homology modeling, mostly based on Kv and HCN crystals, have permitted the identification of several regions contributing to plant Shaker channel gating. In the present mini-review, we make an update on the voltage-gating mechanism of plant Shaker channels which seem to be comparable to that proposed for HCN channels.
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Affiliation(s)
- Manuel Nieves-Cordones
- Biochimie et Physiologie Moléculaire des Plantes; Institut de Biologie Intégrative des Plantes; Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2; Montpellier, France
- Correspondence to: Manuel Nieves-Cordones; , Isabelle Gaillard;
| | - Isabelle Gaillard
- Biochimie et Physiologie Moléculaire des Plantes; Institut de Biologie Intégrative des Plantes; Unité Mixte de Recherche 5004 Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386 Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2; Montpellier, France
- Correspondence to: Manuel Nieves-Cordones; , Isabelle Gaillard;
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Abdel-Hamid H, Chin K, Moeder W, Shahinas D, Gupta D, Yoshioka K. A suppressor screen of the chimeric AtCNGC11/12 reveals residues important for intersubunit interactions of cyclic nucleotide-gated ion channels. PLANT PHYSIOLOGY 2013; 162:1681-93. [PMID: 23735507 PMCID: PMC3707543 DOI: 10.1104/pp.113.217539] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 06/01/2013] [Indexed: 05/23/2023]
Abstract
To investigate the structure-function relationship of plant cyclic nucleotide-gated ion channels (CNGCs), we identified a total of 29 mutant alleles of the chimeric AtCNGC11/12 gene that induces multiple defense responses in the Arabidopsis (Arabidopsis thaliana) mutant, constitutive expresser of PR genes22 (cpr22). Based on computational modeling, two new alleles, S100 (AtCNGC11/12:G459R) and S137 (AtCNGC11/12:R381H), were identified as counterparts of human CNGA3 (a human CNGC) mutants. Both mutants lost all cpr22-mediated phenotypes. Transient expression in Nicotiana benthamiana as well as functional complementation in yeast (Saccharomyces cerevisiae) showed that both AtCNGC11/12:G459R and AtCNGC11/12:R381H have alterations in their channel function. Site-directed mutagenesis coupled with fast-protein liquid chromatography using recombinantly expressed C-terminal peptides indicated that both mutations significantly influence subunit stoichiometry to form multimeric channels. This observation was confirmed by bimolecular fluorescence complementation in planta. Taken together, we have identified two residues that are likely important for subunit interaction for plant CNGCs and likely for animal CNGCs as well.
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Sharma T, Dreyer I, Riedelsberger J. The role of K(+) channels in uptake and redistribution of potassium in the model plant Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2013; 4:224. [PMID: 23818893 PMCID: PMC3694395 DOI: 10.3389/fpls.2013.00224] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/09/2013] [Indexed: 05/17/2023]
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.
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Affiliation(s)
- Tripti Sharma
- Molecular Biology, Institute for Biochemistry and Biology, University of PotsdamPotsdam, Germany
- IMPRS-PMPG, Max-Planck Institute of Molecular Plant PhysiologyPotsdam, Germany
| | - Ingo Dreyer
- Centro de Biotecnologia y Genomica de Plantas, Universidad Politécnica de MadridMadrid, Spain
- *Correspondence: Ingo Dreyer, Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, Pozuelo de Alarcón, Madrid E-28223, Spain e-mail:
| | - Janin Riedelsberger
- Molecular Biology, Institute for Biochemistry and Biology, University of PotsdamPotsdam, Germany
- IMPRS-PMPG, Max-Planck Institute of Molecular Plant PhysiologyPotsdam, Germany
- Janin Riedelsberger, Molecular Biology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24/25, House 20, D-14476 Potsdam, Germany e-mail:
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Abstract
Since the first recordings of single potassium channel activities in the plasma membrane of guard cells more than 25 years ago, patch-clamp studies discovered a variety of ion channels in all cell types and plant species under inspection. Their properties differed in a cell type- and cell membrane-dependent manner. Guard cells, for which the existence of plant potassium channels was initially documented, advanced to a versatile model system for studying plant ion channel structure, function, and physiology. Interestingly, one of the first identified potassium-channel genes encoding the Shaker-type channel KAT1 was shown to be highly expressed in guard cells. KAT1-type channels from Arabidopsis thaliana and its homologs from other species were found to encode the K+-selective inward rectifiers that had already been recorded in early patch-clamp studies with guard cells. Within the genome era, additional Arabidopsis Shaker-type channels appeared. All nine members of the Arabidopsis Shaker family are localized at the plasma membrane, where they either operate as inward rectifiers, outward rectifiers, weak voltage-dependent channels, or electrically silent, but modulatory subunits. The vacuole membrane, in contrast, harbors a set of two-pore K+ channels. Just very recently, two plant anion channel families of the SLAC/SLAH and ALMT/QUAC type were identified. SLAC1/SLAH3 and QUAC1 are expressed in guard cells and mediate Slow- and Rapid-type anion currents, respectively, that are involved in volume and turgor regulation. Anion channels in guard cells and other plant cells are key targets within often complex signaling networks. Here, the present knowledge is reviewed for the plant ion channel biology. Special emphasis is drawn to the molecular mechanisms of channel regulation, in the context of model systems and in the light of evolution.
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Affiliation(s)
- Rainer Hedrich
- University of Wuerzburg, Institute for Molecular Plant Physiology and Biophysics, Wuerzburg, Germany; and King Saud University, Riyadh, Saudi Arabia
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Hills A, Chen ZH, Amtmann A, Blatt MR, Lew VL. OnGuard, a computational platform for quantitative kinetic modeling of guard cell physiology. PLANT PHYSIOLOGY 2012; 159:1026-42. [PMID: 22635116 PMCID: PMC3387691 DOI: 10.1104/pp.112.197244] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 05/20/2012] [Indexed: 05/17/2023]
Abstract
Stomatal guard cells play a key role in gas exchange for photosynthesis while minimizing transpirational water loss from plants by opening and closing the stomatal pore. Foliar gas exchange has long been incorporated into mathematical models, several of which are robust enough to recapitulate transpirational characteristics at the whole-plant and community levels. Few models of stomata have been developed from the bottom up, however, and none are sufficiently generalized to be widely applicable in predicting stomatal behavior at a cellular level. We describe here the construction of computational models for the guard cell, building on the wealth of biophysical and kinetic knowledge available for guard cell transport, signaling, and homeostasis. The OnGuard software was constructed with the HoTSig library to incorporate explicitly all of the fundamental properties for transporters at the plasma membrane and tonoplast, the salient features of osmolite metabolism, and the major controls of cytosolic-free Ca²⁺ concentration and pH. The library engenders a structured approach to tier and interrelate computational elements, and the OnGuard software allows ready access to parameters and equations 'on the fly' while enabling the network of components within each model to interact computationally. We show that an OnGuard model readily achieves stability in a set of physiologically sensible baseline or Reference States; we also show the robustness of these Reference States in adjusting to changes in environmental parameters and the activities of major groups of transporters both at the tonoplast and plasma membrane. The following article addresses the predictive power of the OnGuard model to generate unexpected and counterintuitive outputs.
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Affiliation(s)
| | | | - Anna Amtmann
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.H., Z.-H.C., A.A., M.R.B.); and Physiological Laboratory, University of Cambridge, Cambridge CB2 3EG, United Kingdom (V.L.L.)
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The pH sensor of the plant K+-uptake channel KAT1 is built from a sensory cloud rather than from single key amino acids. Biochem J 2012; 442:57-63. [DOI: 10.1042/bj20111498] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
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 (Kin) that then can open their pores with lower energy cost. The sensory units for extracellular pH in stomatal Kin channels are proposed to be histidines exposed to the apoplasm. However, in the Arabidopsis thaliana stomatal Kin channel KAT1, mutations in the unique histidine exposed to the solvent (His267) do not affect the pH dependency. We demonstrate in the present study that His267 of the KAT1 channel cannot sense pH changes since the neighbouring residue Phe266 shifts its pKa to undetectable values through a cation–π interaction. Instead, we show that Glu240 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 Glu240, 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.
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Abstract
Potassium (K(+) ) is the most abundant inorganic cation in plant cells. Unlike animals, plants lack sodium/potassium exchangers. Instead, plant cells have developed unique transport systems for K(+) accumulation and release. An essential role in potassium uptake and efflux is played by potassium channels. Since the first molecular characterization of K(+) channels from Arabidopsis thaliana in 1992, a large number of studies on plant potassium channels have been conducted. Potassium channels are considered to be one of the best characterized class of membrane proteins in plants. Nevertheless, knowledge on plant potassium channels is still incomplete. This minireview focuses on recent developments in the research of potassium transport in plants with a strong focus on voltage-gated potassium channels.
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Affiliation(s)
- Ingo Dreyer
- Centro de Biotecnologia y Genomica de Plantas, Universidad Politécnica de Madrid, Madrid, Spain.
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Jeanguenin L, Alcon C, Duby G, Boeglin M, Chérel I, Gaillard I, Zimmermann S, Sentenac H, Véry AA. AtKC1 is a general modulator of Arabidopsis inward Shaker channel activity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 67:570-582. [PMID: 21518051 DOI: 10.1111/j.1365-313x.2011.04617.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A functional Shaker potassium channel requires assembly of four α-subunits encoded by a single gene or various genes from the Shaker family. In Arabidopsis thaliana, AtKC1, a Shaker α-subunit that is silent when expressed alone, has been shown to regulate the activity of AKT1 by forming heteromeric AtKC1-AKT1 channels. Here, we investigated whether AtKC1 is a general regulator of channel activity. Co-expression in Xenopus oocytes of a dominant negative (pore-mutated) AtKC1 subunit with the inward Shaker channel subunits KAT1, KAT2 or AKT2, or the outward subunits SKOR or GORK, revealed that the three inward subunits functionally interact with AtKC1 while the outward ones cannot. Localization experiments in plant protoplasts showed that KAT2 was able to re-locate AtKC1 fused to GFP from endomembranes to the plasma membrane, indicating that heteromeric AtKC1-KAT2 channels are efficiently targeted to the plasma membrane. Functional properties of heteromeric channels involving AtKC1 and KAT1, KAT2 or AKT2 were analysed by voltage clamp after co-expression of the respective subunits in Xenopus oocytes. AtKC1 behaved as a regulatory subunit within the heterotetrameric channel, reducing the macroscopic conductance and negatively shifting the channel activation potential. Expression studies showed that AtKC1 and its identified Shaker partners have overlapping expression patterns, supporting the hypothesis of a general regulation of inward channel activity by AtKC1 in planta. Lastly, AtKC1 disruption appeared to reduce plant biomass production, showing that AtKC1-mediated channel activity regulation is required for normal plant growth.
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Affiliation(s)
- Linda Jeanguenin
- Biochimie et Physiologie Moléculaire des Plantes, UMR CNRS (5004)/INRA (388)/SupAgro/UM2, Campus INRA/Montpellier SupAgro, 2 Place Viala, 34060 Montpellier Cedex 2, France
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Chen IH, Hu JH, Jow GM, Chuang CC, Lee TT, Liu DC, Jeng CJ. Distal end of carboxyl terminus is not essential for the assembly of rat Eag1 potassium channels. J Biol Chem 2011; 286:27183-96. [PMID: 21646358 DOI: 10.1074/jbc.m111.233825] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The assembly of four pore-forming α-subunits into tetramers is a prerequisite for the formation of functional K(+) channels. A short carboxyl assembly domain (CAD) in the distal end of the cytoplasmic carboxyl terminus has been implicated in the assembly of Eag α-subunits, a subfamily of the ether-à-go-go K(+) channel family. The precise role of CAD in the formation of Eag tetrameric channels, however, remains unclear. Moreover, it has not been determined whether other protein regions also contribute to the assembly of Eag subunits. We addressed these questions by studying the biophysical properties of a series of different rat Eag1 (rEag1) truncation mutants. Two truncation mutants without CAD (K848X and W823X) yielded functional phenotypes similar to those for wild-type (WT) rEag1 channels. Furthermore, nonfunctional rEag1 truncation mutants lacking the distal region of the carboxyl terminus displayed substantial dominant-negative effects on the functional expression of WT as well as K848X and W823X channels. Our co-immunoprecipitation studies further revealed that truncation mutants containing no CAD indeed displayed significant association with rEag1-WT subunits. Finally, surface biotinylation and protein glycosylation analyses demonstrated that progressive truncations of the carboxyl terminus resulted in aggravating disruptions of membrane trafficking and glycosylation of rEag1 proteins. Overall, our data suggest that the distal carboxyl terminus, including CAD, is dispensable for the assembly of rEag1 K(+) channels but may instead be essential for ensuring proper protein biosynthesis. We propose that the S6 segment and the proximal carboxyl terminus may constitute the principal subunit recognition site for the assembly of rEag1 channels.
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Affiliation(s)
- I-Hsiu Chen
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei 12212, Taiwan
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39
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Functional Classification of Plant Plasma Membrane Transporters. THE PLANT PLASMA MEMBRANE 2011. [DOI: 10.1007/978-3-642-13431-9_6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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41
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Voelker C, Gomez-Porras JL, Becker D, Hamamoto S, Uozumi N, Gambale F, Mueller-Roeber B, Czempinski K, Dreyer I. Roles of tandem-pore K+ channels in plants - a puzzle still to be solved. PLANT BIOLOGY (STUTTGART, GERMANY) 2010; 12 Suppl 1:56-63. [PMID: 20712621 DOI: 10.1111/j.1438-8677.2010.00353.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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.
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Affiliation(s)
- C Voelker
- Institute of Biochemistry and Biology, Molecular Biology, University of Potsdam, Potsdam-Golm, Germany.
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42
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Garcia-Mata C, Wang J, Gajdanowicz P, Gonzalez W, Hills A, Donald N, Riedelsberger J, Amtmann A, Dreyer I, Blatt MR. A minimal cysteine motif required to activate the SKOR K+ channel of Arabidopsis by the reactive oxygen species H2O2. J Biol Chem 2010; 285:29286-94. [PMID: 20605786 DOI: 10.1074/jbc.m110.141176] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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 Ca(2+) 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 H(2)O(2). We show that H(2)O(2) rapidly enhanced current amplitude and activation kinetics of heterologously expressed SKOR, and the effects were reversed by the reducing agent dithiothreitol (DTT). Both H(2)O(2) and DTT were active at the outer face of the membrane and current enhancement was strongly dependent on membrane depolarization, consistent with a H(2)O(2)-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 α-helix of the voltage sensor complex, to be essential for sensitivity to H(2)O(2). The same Cys residue was a primary determinant for current block by covalent Cys S-methioylation with aqueous methanethiosulfonates. These, and additional data identify Cys(168) as a critical target for H(2)O(2), and implicate ROS-mediated control of the K(+) channel in regulating mineral nutrient partitioning within the plant.
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Affiliation(s)
- Carlos Garcia-Mata
- Laboratory of Plant Physiology and Biophysics, Faculty of Biomedical and Life Sciences, Plant Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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K+ transport characteristics of the plasma membrane tandem-pore channel TPK4 and pore chimeras with its vacuolar homologs. FEBS Lett 2010; 584:2433-9. [PMID: 20412800 DOI: 10.1016/j.febslet.2010.04.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2010] [Revised: 04/08/2010] [Accepted: 04/14/2010] [Indexed: 11/23/2022]
Abstract
Vacuolar tandem-pore channels could not be analysed in Xenopus oocytes so far, due to misguided translocation. Owing to the conservation of their pore regions, we were able to prepare functional pore-chimeras between the plasma membrane localised TPK4 and vacuolar TPKs. Thereby, we found evidence that TPK2, TPK3 and TPK5, just like TPK4, form potassium-selective channels with instantaneous current kinetics. Homology modelling and mutational analyses identified a pore-located aspartate residue (Asp110), which is involved in potassium permeation as well as in inward rectification of TPK4. Furthermore, dominant-negative mutations in the selectivity filter of either pore one or two (Asp86,Asp200) rendered TPK4 non-functional. This observation supports the notion that the functional TPK4 channel complex is formed by two subunits.
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Riedelsberger J, Sharma T, Gonzalez W, Gajdanowicz P, Morales-Navarro SE, Garcia-Mata C, Mueller-Roeber B, González-Nilo FD, Blatt MR, Dreyer I. Distributed structures underlie gating differences between the kin channel KAT1 and the Kout channel SKOR. MOLECULAR PLANT 2010; 3:236-245. [PMID: 20007672 DOI: 10.1093/mp/ssp096] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The family of voltage-gated (Shaker-like) potassium channels in plants 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, K(in) and K(out) channels differ in their gating sensitivity towards voltage and the extracellular K(+) concentration. We have carried out a systematic program of domain swapping between the K(out) channel SKOR and the K(in) channel KAT1 to examine the impacts on gating of the pore regions, the S4, S5, and the S6 helices. We found that, in particular, the N-terminal part of the S5 played a critical role in KAT1 and SKOR gating. Our findings were supported by molecular dynamics of KAT1 and SKOR homology models. In silico analysis revealed that during channel opening and closing, displacement of certain residues, especially in the S5 and S6 segments, is more pronounced in KAT1 than in SKOR. From our analysis of the S4-S6 region, we conclude that gating (and K(+)-sensing in SKOR) depend on a number of structural elements that are dispersed over this approximately 145-residue sequence and that these place additional constraints on configurational rearrangement of the channels during gating.
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Affiliation(s)
- Janin Riedelsberger
- Universität Potsdam, Institut für Biochemie und Biologie, Molekularbiologie, Heisenberg-Gruppe Biophysik und Molekulare Pflanzenbiologie BPMPB, Karl-Liebknecht-Strasse 24-25, Haus 20, Potsdam-Golm, Germany
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45
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Lebaudy A, Pascaud F, Véry AA, Alcon C, Dreyer I, Thibaud JB, Lacombe B. Preferential KAT1-KAT2 heteromerization determines inward K+ current properties in Arabidopsis guard cells. J Biol Chem 2009; 285:6265-74. [PMID: 20040603 DOI: 10.1074/jbc.m109.068445] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Guard cells adjust their volume by changing their ion content due to intense fluxes that, for K(+), are believed to flow through inward or outward Shaker channels. Because Shaker channels can be homo- or heterotetramers and Arabidopsis guard cells express at least five genes encoding inward Shaker subunits, including the two major ones, KAT1 and KAT2, the molecular identity of inward Shaker channels operating therein is not yet completely elucidated. Here, we first addressed the properties of KAT1-KAT2 heteromers by expressing KAT1-KAT2 tandems in Xenopus oocytes. Then, computer analyses of the data suggested that coexpression of free KAT1 and KAT2 subunits resulted mainly in heteromeric channels made of two subunits of each type due to some preferential association of KAT1-KAT2 heterodimers at the first step of channel assembly. This was further supported by the analysis of KAT2 effect on KAT1 targeting in tobacco cells. Finally, patch-clamp recordings of native inward channels in wild-type and mutant genotypes strongly suggested that this preferential heteromerization occurs in planta and that Arabidopsis guard cell inward Shaker channels are mainly heteromers of KAT1 and KAT2 subunits.
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Affiliation(s)
- Anne Lebaudy
- Biochimie et Physiologie Moléculaire des Plantes, CNRS UMR 5004, Institut National de la Recherche Agronomique U386, Montpellier SupAgro, Université Montpellier II, Place Viala, 34060 Montpellier Cedex, France
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46
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Naso A, Dreyer I, Pedemonte L, Testa I, Gomez-Porras JL, Usai C, Mueller-Rueber B, Diaspro A, Gambale F, Picco C. The role of the C-terminus for functional heteromerization of the plant channel KDC1. Biophys J 2009; 96:4063-74. [PMID: 19450478 DOI: 10.1016/j.bpj.2009.02.055] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 02/06/2009] [Accepted: 02/17/2009] [Indexed: 12/25/2022] Open
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 K(HA) 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.
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Affiliation(s)
- Alessia Naso
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, 16149 Genoa, Italy
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47
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Dreyer I, Blatt MR. What makes a gate? The ins and outs of Kv-like K+ channels in plants. TRENDS IN PLANT SCIENCE 2009; 14:383-90. [PMID: 19540150 DOI: 10.1016/j.tplants.2009.04.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 04/06/2009] [Accepted: 04/07/2009] [Indexed: 05/18/2023]
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.
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Affiliation(s)
- Ingo Dreyer
- Heisenberg-Group BPMPB, Institut für Biochemie und Biologie, Universität Potsdam, Karl-Liebknecht-Strasse 24/25, Potsdam-Golm, Germany
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48
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Gajdanowicz P, Garcia-Mata C, Gonzalez W, Morales-Navarro SE, Sharma T, González-Nilo FD, Gutowicz J, Mueller-Roeber B, Blatt MR, Dreyer I. Distinct roles of the last transmembrane domain in controlling Arabidopsis K+ channel activity. THE NEW PHYTOLOGIST 2009; 182:380-391. [PMID: 19192193 DOI: 10.1111/j.1469-8137.2008.02749.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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 K(in) 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 K(in) 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.
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Affiliation(s)
- Pawel Gajdanowicz
- Universität Potsdam, Institut für Biochemie und Biologie, Heisenberg-Gruppe Biophysik und Molekulare Pflanzenbiologie, 14476 Potsdam/Golm, Germany
| | - Carlos Garcia-Mata
- Laboratory of Plant Physiology and Biophysics, IBLS Plant Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
- Laboratorio de Fisiologia Molecular e Integrativa, Institutos de Investigaciones Biologicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Buenos Aires, Argentina
| | - Wendy Gonzalez
- Universität Potsdam, Institut für Biochemie und Biologie, Heisenberg-Gruppe Biophysik und Molekulare Pflanzenbiologie, 14476 Potsdam/Golm, Germany
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Casilla 721, Talca, Chile
| | | | - Tripti Sharma
- Universität Potsdam, Institut für Biochemie und Biologie, Heisenberg-Gruppe Biophysik und Molekulare Pflanzenbiologie, 14476 Potsdam/Golm, Germany
- Max-Planck Institute of Molecular Plant Physiology, 14476 Potsdam/Golm, Germany
| | | | - Jan Gutowicz
- Department of Physical Chemistry of Microorganisms, Institute of Genetics and Microbiology, University of Wrocław, 51148 Wrocław, Poland
| | - Bernd Mueller-Roeber
- Max-Planck Institute of Molecular Plant Physiology, 14476 Potsdam/Golm, Germany
- Universität Potsdam, Institut für Biochemie und Biologie, Abteilung Molekularbiologie, 14476 Potsdam/Golm, Germany
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, IBLS Plant Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Ingo Dreyer
- Universität Potsdam, Institut für Biochemie und Biologie, Heisenberg-Gruppe Biophysik und Molekulare Pflanzenbiologie, 14476 Potsdam/Golm, Germany
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49
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Abstract
Distinct potassium, anion, and calcium channels in the plasma membrane and vacuolar membrane of plant cells have been identified and characterized by patch clamping. Primarily owing to advances in Arabidopsis genetics and genomics, and yeast functional complementation, many of the corresponding genes have been identified. Recent advances in our understanding of ion channel genes that mediate signal transduction and ion transport are discussed here. Some plant ion channels, for example, ALMT and SLAC anion channel subunits, are unique. The majority of plant ion channel families exhibit homology to animal genes; such families include both hyperpolarization- and depolarization-activated Shaker-type potassium channels, CLC chloride transporters/channels, cyclic nucleotide-gated channels, and ionotropic glutamate receptor homologs. These plant ion channels offer unique opportunities to analyze the structural mechanisms and functions of ion channels. Here we review gene families of selected plant ion channel classes and discuss unique structure-function aspects and their physiological roles in plant cell signaling and transport.
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Affiliation(s)
- John M. Ward
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108;
| | - Pascal Mäser
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
| | - Julian I. Schroeder
- Division of Biological Sciences, Cell and Developmental Biology Section, University of California, San Diego, La Jolla, California 92093;
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50
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Dunkel M, Latz A, Schumacher K, Müller T, Becker D, Hedrich R. Targeting of vacuolar membrane localized members of the TPK channel family. MOLECULAR PLANT 2008; 1:938-49. [PMID: 19825594 DOI: 10.1093/mp/ssn064] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Four members of the tandem-pore potassium channel family of Arabidopsis thaliana (TPK1, 2, 3, and 5) reside in the vacuolar membrane, whereas TPK4 is a plasma membrane K(+)-channel. By constructing chimeras between TPK1 and TPK4, we attempted to identify channel domains involved in the trafficking process and found that the TPK1 cytoplasmic C-terminal domain (CT) is critical for the ER- as well as Golgi-sorting steps. Following site-directed mutagenesis, we identified a diacidic motif (DLE) required for ER-export of TPK1. However, this diacidic motif in the C-terminus is not conserved among other members of the TPK family, and TPK3 sorting is independent of its CT. Moreover, the 14-3-3 binding site of TPK1, essential for channel activation, is not involved in channel sorting.
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Affiliation(s)
- Marcel Dunkel
- University of Würzburg, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
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