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Yuan G, Nong T, Hunpatin OS, Shi C, Su X, Wang Q, Liu H, Dai P, Ning Y. Research Progress on Plant Shaker K + Channels. PLANTS (BASEL, SWITZERLAND) 2024; 13:1423. [PMID: 38794493 PMCID: PMC11125005 DOI: 10.3390/plants13101423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/16/2024] [Accepted: 05/16/2024] [Indexed: 05/26/2024]
Abstract
Plant growth and development are driven by intricate processes, with the cell membrane serving as a crucial interface between cells and their external environment. Maintaining balance and signal transduction across the cell membrane is essential for cellular stability and a host of life processes. Ion channels play a critical role in regulating intracellular ion concentrations and potentials. Among these, K+ channels on plant cell membranes are of paramount importance. The research of Shaker K+ channels has become a paradigm in the study of plant ion channels. This study offers a comprehensive overview of advancements in Shaker K+ channels, including insights into protein structure, function, regulatory mechanisms, and research techniques. Investigating Shaker K+ channels has enhanced our understanding of the regulatory mechanisms governing ion absorption and transport in plant cells. This knowledge offers invaluable guidance for enhancing crop yields and improving resistance to environmental stressors. Moreover, an extensive review of research methodologies in Shaker K+ channel studies provides essential reference solutions for researchers, promoting further advancements in ion channel research.
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Affiliation(s)
- Guang Yuan
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Tongjia Nong
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Oluwaseyi Setonji Hunpatin
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Chuhan Shi
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Xiaoqing Su
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Qian Wang
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
| | - Haobao Liu
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
| | - Peigang Dai
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
| | - Yang Ning
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
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Chen X, Luo M, Mo C, Li W, Ji Y, Xie Q, Jiang X. MeCIPK10 regulates the transition of the K + transport activity of MeAKT2 between low- and high-affinity molds in cassava. JOURNAL OF PLANT PHYSIOLOGY 2023; 280:153861. [PMID: 36399835 DOI: 10.1016/j.jplph.2022.153861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/04/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
AKT1 is an inward-rectifying K+ channel that was originally thought to function only within a low-affinity K+ concentration range. However, the growth of an akt1 mutant of Arabidopsis was shown to be severely inhibited within a high-affinity range. This suggested that AKT1 may also be a high-affinity K+ transporter, but it remains unclear how the two modes of AKT1 coordinate to uptake K+. One gene (MeAKT2) encodes for a putatively inward-rectifying K+ channel and was isolated from cassava. Relative to other tissues, the MeAKT2 gene was expressed mainly in roots, and its transcriptional level was observed to be significantly increased under low-K+ conditions. Functional analyses were performed using a yeast expression system. When MeAKT2 was expressed alone in yeast cells, transgenic yeast could grow only in nutrient media supplied with >0.5 mM potassium. A yeast two-hybrid assay showed that both MeCIPK10 and MeCIPK12 clearly interacted with MeAKT2. Additionally, 0.05 mM K+ was sufficient for the growth of yeast cells co-expressing MeAKT2 with MeCIPK10, but also their co-expression significantly enhanced the growth capacity of yeast cells in the low range of K+ concentrations. Change in K+ uptake rate in co-transgenic yeast cells grown across a wide range of K+ concentrations showed that MeAKT2-mediated K+ uptake displayed a biphasic pattern, but also the switching from low-to high-affinity K+ uptake was regulated by CIPK10. This indicated that MeAKT2 functioned as a dual-affinity transporter to uptake K+ under both low- and high-affinity K+ conditions.
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Affiliation(s)
- Xiuzhen Chen
- National Center for Technology Innovation of Saline-Alkali Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, China; Hainan Key Laboratory for Biotechnology of Salt Tolerant Crops/Institute of Tropical Crops, Hainan University, Haikou, 570228, China; Lixia District Center for Disease Control and Prevention, Jinan, 250014, China
| | - Minghua Luo
- National Center for Technology Innovation of Saline-Alkali Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, China; Hainan Key Laboratory for Biotechnology of Salt Tolerant Crops/Institute of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Chunyan Mo
- Hainan Key Laboratory for Biotechnology of Salt Tolerant Crops/Institute of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Wenjia Li
- Hainan Key Laboratory for Biotechnology of Salt Tolerant Crops/Institute of Tropical Crops, Hainan University, Haikou, 570228, China
| | - Yiying Ji
- National Center for Technology Innovation of Saline-Alkali Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, China
| | - Qing Xie
- National Center for Technology Innovation of Saline-Alkali Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, China.
| | - Xingyu Jiang
- National Center for Technology Innovation of Saline-Alkali Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, China; Hainan Key Laboratory for Biotechnology of Salt Tolerant Crops/Institute of Tropical Crops, Hainan University, Haikou, 570228, China.
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3
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Structural basis for the activity regulation of a potassium channel AKT1 from Arabidopsis. Nat Commun 2022; 13:5682. [PMID: 36167696 PMCID: PMC9515098 DOI: 10.1038/s41467-022-33420-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 09/16/2022] [Indexed: 11/25/2022] Open
Abstract
The voltage-gated potassium channel AKT1 is responsible for primary K+ uptake in Arabidopsis roots. AKT1 is functionally activated through phosphorylation and negatively regulated by a potassium channel α-subunit AtKC1. However, the molecular basis for the modulation mechanism remains unclear. Here we report the structures of AKT1, phosphorylated-AKT1, a constitutively-active variant, and AKT1-AtKC1 complex. AKT1 is assembled in 2-fold symmetry at the cytoplasmic domain. Such organization appears to sterically hinder the reorientation of C-linkers during ion permeation. Phosphorylated-AKT1 adopts an alternate 4-fold symmetric conformation at cytoplasmic domain, which indicates conformational changes associated with symmetry switch during channel activation. To corroborate this finding, we perform structure-guided mutagenesis to disrupt the dimeric interface and identify a constitutively-active variant Asp379Ala mediates K+ permeation independently of phosphorylation. This variant predominantly adopts a 4-fold symmetric conformation. Furthermore, the AKT1-AtKC1 complex assembles in 2-fold symmetry. Together, our work reveals structural insight into the regulatory mechanism for AKT1. Arabidopsis thaliana potassium channel AKT1 is responsible for primary K + uptake from soil, which is functionally activated through phosphorylation and negatively regulated by an α-subunit AtKC1. Here, the authors report the structures of AKT1 at different states, revealing a 2- fold to 4-fold symmetry switch at cytoplasmic domain associated with AKT1 activity regulation.
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Mao Y, Yin Y, Cui X, Wang H, Su X, Qin X, Liu Y, Hu Y, Shen X. Homologous Cloning of Potassium Channel Genes From the Superior Apple Rootstock Line 12-2, Which is Tolerant to Apple Replant Disease. Front Genet 2022; 13:803160. [PMID: 35154275 PMCID: PMC8826240 DOI: 10.3389/fgene.2022.803160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Abstract
Potassium channels are important ion channels that are responsible for the absorption of potassium in the plant nutrient uptake system. In this study, we used homologous molecular cloning to obtain 8 K+ channel genes from the superior apple rootstock line 12-2 (self-named): MsAKT1-1, MsKAT3-2, MsKAT1-3, MsK2P3-4, MsK2P3-5, MsK2P5-6, MsK2P3-7, and MsK2P3-8. Their lengths varied from 942 bp (MsK2P5-6) to 2625 bp (MsAKT1-1), and the number of encoded amino acids varied from 314 (MsK2P5-6) to 874 (MsAKT1-1). Subcellular localization predictions showed that MsAKT1-1, MsKAT3-2, and MsKAT1-3 were localized on the plasma membrane, and MsK2P3-4, MsK2P3-5, MsK2P5-6, MsK2P3-7, and MsK2P3-8 were localized on the vacuole and plasma membrane. The 8 K+ channel proteins contained α helices, extended strands, β turns, and random coils. MsKAT1-3 had four transmembrane structures, MsKAT3-2 had six, and the other six K+ channel genes had five. Protein structure domain analysis showed that MsAKT1-1 contained nine protein domains, followed by MsKAT3-2 with four, MsKAT1-3 with three, and the other five two-pore domain K+ channel proteins with two. Semi-quantitative RT-PCR detection of the K+ channel genes showed that their expression levels were high in roots. qRT-PCR analysis showed that the relative expression levels of the 8 genes changed after exposure to ARD stress. The above results provide a theoretical basis for further research on the functions of potassium channel genes in 12-2 and a scientific basis for the breeding of ARD-resistant rootstock.
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Affiliation(s)
- Yunfei Mao
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - Yijun Yin
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - Xueli Cui
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - Haiyan Wang
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - XiaFei Su
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - Xin Qin
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - Yangbo Liu
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - Yanli Hu
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - Xiang Shen
- National Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China
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Kashtoh H, Baek KH. Structural and Functional Insights into the Role of Guard Cell Ion Channels in Abiotic Stress-Induced Stomatal Closure. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10122774. [PMID: 34961246 PMCID: PMC8707303 DOI: 10.3390/plants10122774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 11/25/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
A stomatal pore is formed by a pair of specialized guard cells and serves as a major gateway for water transpiration and atmospheric CO2 influx for photosynthesis in plants. These pores must be tightly controlled, as inadequate CO2 intake and excessive water loss are devastating for plants. When the plants are exposed to extreme weather conditions such as high CO2 levels, O3, low air humidity, and drought, the turgor pressure of the guard cells exhibits an appropriate response against these stresses, which leads to stomatal closure. This phenomenon involves a complex network of ion channels and their regulation. It is well-established that the turgor pressure of guard cells is regulated by ions transportation across the membrane, such as anions and potassium ions. In this review, the guard cell ion channels are discussed, highlighting the structure and functions of key ion channels; the SLAC1 anion channel and KAT1 potassium channel, and their regulatory components, emphasizing their significance in guard cell response to various stimuli.
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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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Uehara C, Takeda K, Ibuki T, Furuta T, Hoshi N, Tanudjaja E, Uozumi N. Analysis of Arabidopsis TPK2 and KCO3 reveals structural properties required for K + channel function. Channels (Austin) 2020; 14:336-346. [PMID: 33016199 PMCID: PMC7757853 DOI: 10.1080/19336950.2020.1825894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Arabidopsis thaliana contains five tandem-pore domain potassium channels, TPK1-TPK5 and the related one-pore domain potassium channel, KCO3. Although KCO3 is unlikely to be an active channel, it still has a physiological role in plant cells. TPK2 is most similar to KCO3 and both are localized to the tonoplast. However, their function remains poorly understood. Here, taking advantage of the similarities between TPK2 and KCO3, we evaluated Ca2+ binding to the EF hands in TPK2, and the elements of KCO3 required for K+ channel activity. Presence of both EF-hand motifs in TPK2 resulted in Ca2+ binding, but EF1 or EF2 alone failed to interact with Ca2+. The EF hands were not required for K+ transport activity. EF1 contains two cysteines separated by two amino acids. Replacement of both cysteines with serines in TPK2 increased Ca2+ binding. We generated a two-pore domain chimeric K+ channel by replacing the missing pore region in KCO3 with a pore domain of TPK2. Alternatively, we generated two versions of simple one-pore domain K+ channels by removal of an extra region from KCO3. The chimera and one of the simple one-pore variants were functional channels. This strongly suggests that KCO3 is not a pseudogene and KCO3 retains components required for the formation of a functional K+ channel and oligomerization. Our results contribute to our understanding of the structural properties required for K+ channel activity.
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Affiliation(s)
- Chihiro Uehara
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University , Sendai, Japan
| | - Kota Takeda
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University , Sendai, Japan.,Bioscience and Biotechnology Center, Nagoya University , Nagoya, Japan
| | - Tatsuki Ibuki
- Bioscience and Biotechnology Center, Nagoya University , Nagoya, Japan
| | - Tadaomi Furuta
- School of Life Science and Technology, Tokyo Institute of Technology , Yokohama, Japan
| | - Naomi Hoshi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University , Sendai, Japan
| | - Ellen Tanudjaja
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University , Sendai, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University , Sendai, Japan
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8
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Chen G, Chen Q, Qi K, Xie Z, Yin H, Wang P, Wang R, Huang Z, Zhang S, Wang L, Wu J. Identification of Shaker K + channel family members in Rosaceae and a functional exploration of PbrKAT1. PLANTA 2019; 250:1911-1925. [PMID: 31523779 DOI: 10.1007/s00425-019-03275-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 09/06/2019] [Indexed: 05/20/2023]
Abstract
PbrKAT1, which is inhibited by external Na+ in Xenopus laevis oocytes, is characterized as encoding a typical inward rectifying channel that is mainly expressed in guard cells. Potassium (K+) is the most abundant cation in plant cells necessary for plant growth and development. The uptake and transport of K+ are mainly completed through transporters and channels, and the Shaker family genes are the most studied K+ channels in plants. However, there is far less information about this family in Rosaceae species. We performed a genome-wide analysis and identified Shaker K+ channel gene family members in Rosaceae. We cloned and characterized a Shaker K+ channel KAT1 from pear (Pyrus × bretschneideri). In total, 36 Shaker K+ channel genes were identified from Rosaceae species and were classified into five subgroups based on structural characteristics and a phylogenetic analysis. Whole-genome and dispersed duplications were the primary forces underlying Shaker K+ channel gene family expansion in Rosaceae, and purifying selection played a key role in the evolution of Shaker K+ channel genes. β-Glucuronidase and qRT-PCR assays revealed that PbrKAT1 was mainly expressed in leaves, especially in guard cells. PbrKAT1 displayed a typical inward-rectifying current when expressed in Xenopus laevis oocytes. The activity of PbrKAT1 was inhibited by external sodium ions, possibly playing an important role in the regulation of salt tolerance in pear. These results provide valuable information on evolution, expression and functions of the Shaker K+ channel gene family in plants.
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Affiliation(s)
- Guodong Chen
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Qian Chen
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Kaijie Qi
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhihua Xie
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Hao Yin
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Peng Wang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Runze Wang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhi Huang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Shaoling Zhang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Li Wang
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Juyou Wu
- Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China.
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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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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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Locascio A, Marqués MC, García-Martínez G, Corratgé-Faillie C, Andrés-Colás N, Rubio L, Fernández JA, Véry AA, Mulet JM, Yenush L. BCL2-ASSOCIATED ATHANOGENE4 Regulates the KAT1 Potassium Channel and Controls Stomatal Movement. PLANT PHYSIOLOGY 2019; 181:1277-1294. [PMID: 31451552 PMCID: PMC6836829 DOI: 10.1104/pp.19.00224] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 08/05/2019] [Indexed: 05/18/2023]
Abstract
Potassium (K+) is a key monovalent cation necessary for multiple aspects of cell growth and survival. In plants, this cation also plays a key role in the control of stomatal movement. KAT1 and its homolog KAT2 are the main inward rectifying channels present in guard cells, mediating K+ influx into these cells, resulting in stomatal opening. To gain further insight into the regulation of these channels, we performed a split-ubiquitin protein-protein interaction screen searching for KAT1 interactors in Arabidopsis (Arabidopsis thaliana). We characterized one of these candidates, BCL2-ASSOCIATED ATHANOGENE4 (BAG4), in detail using biochemical and genetic approaches to confirm this interaction and its effect on KAT1 activity. We show that BAG4 improves KAT1-mediated K+ transport in two heterologous systems and provide evidence that in plants, BAG4 interacts with KAT1 and favors the arrival of KAT1 at the plasma membrane. Importantly, lines lacking or overexpressing the BAG4 gene show altered KAT1 plasma membrane accumulation and alterations in stomatal movement. Our data allowed us to identify a KAT1 regulator and define a potential target for the plant BAG family. The identification of physiologically relevant regulators of K+ channels will aid in the design of approaches that may impact drought tolerance and pathogen susceptibility.
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Affiliation(s)
- Antonella Locascio
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain
| | - Maria Carmen Marqués
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain
| | - Guillermo García-Martínez
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain
| | - Claire Corratgé-Faillie
- Biochimie et Physiologie Moléculaire des Plantes, Université Montpellier, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique (INRA), SupAgro Montpellier, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France
| | - Nuria Andrés-Colás
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain
| | - Lourdes Rubio
- Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos S/N, 29010 Málaga, Spain
| | - José Antonio Fernández
- Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos S/N, 29010 Málaga, Spain
| | - Anne-Aliénor Véry
- Biochimie et Physiologie Moléculaire des Plantes, Université Montpellier, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique (INRA), SupAgro Montpellier, Campus SupAgro-INRA, 34060 Montpellier Cedex 2, France
| | - José Miguel Mulet
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain
| | - Lynne Yenush
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain
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12
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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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13
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The Complex Fine-Tuning of K⁺ Fluxes in Plants in Relation to Osmotic and Ionic Abiotic Stresses. Int J Mol Sci 2019; 20:ijms20030715. [PMID: 30736441 PMCID: PMC6387338 DOI: 10.3390/ijms20030715] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 01/17/2019] [Accepted: 01/29/2019] [Indexed: 12/19/2022] Open
Abstract
As the main cation in plant cells, potassium plays an essential role in adaptive responses, especially through its involvement in osmotic pressure and membrane potential adjustments. K+ homeostasis must, therefore, be finely controlled. As a result of different abiotic stresses, especially those resulting from global warming, K⁺ fluxes and plant distribution of this ion are disturbed. The hormone abscisic acid (ABA) is a key player in responses to these climate stresses. It triggers signaling cascades that ultimately lead to modulation of the activities of K⁺ channels and transporters. After a brief overview of transcriptional changes induced by abiotic stresses, this review deals with the post-translational molecular mechanisms in different plant organs, in Arabidopsis and species of agronomical interest, triggering changes in K⁺ uptake from the soil, K⁺ transport and accumulation throughout the plant, and stomatal regulation. These modifications involve phosphorylation/dephosphorylation mechanisms, modifications of targeting, and interactions with regulatory partner proteins. Interestingly, many signaling pathways are common to K⁺ and Cl-/NO3- counter-ion transport systems. These cross-talks are also addressed.
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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. [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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15
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Adams E, Miyazaki T, Saito S, Uozumi N, Shin R. Cesium Inhibits Plant Growth Primarily Through Reduction of Potassium Influx and Accumulation in Arabidopsis. PLANT & CELL PHYSIOLOGY 2019; 60:63-76. [PMID: 30219884 DOI: 10.1093/pcp/pcy188] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Indexed: 05/17/2023]
Abstract
Cesium (Cs+) is known to compete with the macronutrient potassium (K+) inside and outside of plants and to inhibit plant growth at high concentrations. However, the detailed molecular mechanisms of how Cs+ exerts its deleterious effects on K+ accumulation in plants are not fully elucidated. Here, we show that mutation in a member of the major K+ channel AKT1-KC1 complex renders Arabidopsis thaliana hypersensitive to Cs+. Higher severity of the phenotype and K+ loss were observed for these mutants in response to Cs+ than to K+ deficiency. Electrophysiological analysis demonstrated that Cs+, but not sodium, rubidium or ammonium, specifically inhibited K+ influx through the AKT1-KC1 complex. In contrast, Cs+ did not inhibit K+ efflux through the homomeric AKT1 channel that occurs in the absence of KC1, leading to a vast loss of K+. Our observation suggests that reduced K+ accumulation due to blockage/competition in AKT1 and other K+ transporters/channels by Cs+ plays a major role in plant growth retardation. This report describes the mechanical role of Cs+ in K+ accumulation, and in turn in plant performance, providing actual evidence at the plant level for what has long been believed, i.e. K+ channels are, therefore AKT1 is, 'blocked' by Cs+.
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Affiliation(s)
- Eri Adams
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan
| | - Takae Miyazaki
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan
| | - Shunya Saito
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Ryoung Shin
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan
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16
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Jegla T, Busey G, Assmann SM. Evolution and Structural Characteristics of Plant Voltage-Gated K + Channels. THE PLANT CELL 2018; 30:2898-2909. [PMID: 30389753 PMCID: PMC6354262 DOI: 10.1105/tpc.18.00523] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/09/2018] [Accepted: 10/30/2018] [Indexed: 05/18/2023]
Abstract
Plant voltage-gated K+ channels have been referred to as "plant Shakers" in reference to animal Shaker channels, the first K+ channels identified. Recent advances in our knowledge of K+ channel evolution and structure have significantly deepened the divide between these plant and animal K+ channels, suggesting that it is time to completely retire the "plant Shaker" designation. Evolutionary genomics reveals that plant voltage-gated K+ channels and metazoan Shakers derive from distinct prokaryotic ancestors. The plant channels belong to a lineage that includes cyclic nucleotide-gated channels and metazoan ether-à-go-go and hyperpolarization-activated, cyclic nucleotide-gated channels. We refer to this lineage as the CNBD channel superfamily, because all these channels share a cytoplasmic gating domain homologous to cyclic nucleotide binding domains. The first structures of CNBD superfamily channels reveal marked differences in coupling between the voltage sensor and ion-conducting pore relative to metazoan Shaker channels. Viewing plant voltage-gated K+ channel function through the lens of CNBD superfamily structures should lead to insights into how these channels are regulated.
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Affiliation(s)
- Timothy Jegla
- Department of Biology and Huck Institute for the Life Sciences, Penn State University, 230 Life Sciences Building, University Park, Pennsylvania 16802
| | - Gregory Busey
- Department of Biology, Penn State University, 225 Life Sciences Building, University Park, Pennsylvania 16802
| | - Sarah M Assmann
- Department of Biology, Penn State University, 354 North Frear, University Park, Pennsylvania 16802
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17
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18
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Gao YQ, Wu WH, Wang Y. The K + channel KZM2 is involved in stomatal movement by modulating inward K + currents in maize guard cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:662-675. [PMID: 28891257 DOI: 10.1111/tpj.13712] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 08/28/2017] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
Stomata are the major gates in plant leaf that allow water and gas exchange, which is essential for plant transpiration and photosynthesis. Stomatal movement is mainly controlled by the ion channels and transporters in guard cells. In Arabidopsis, the inward Shaker K+ channels, such as KAT1 and KAT2, are responsible for stomatal opening. However, the characterization of inward K+ channels in maize guard cells is limited. In the present study, we identified two KAT1-like Shaker K+ channels, KZM2 and KZM3, which were highly expressed in maize guard cells. Subcellular analysis indicated that KZM2 and KZM3 can localize at the plasma membrane. Electrophysiological characterization in HEK293 cells revealed that both KZM2 and KZM3 were inward K+ (Kin ) channels, but showing distinct channel kinetics. When expressed in Xenopus oocytes, only KZM3, but not KZM2, can mediate inward K+ currents. However, KZM2 can interact with KZM3 forming heteromeric Kin channel. In oocytes, KZM2 inhibited KZM3 channel conductance and negatively shifted the voltage dependence of KZM3. The activation of KZM2-KZM3 heteromeric channel became slower than the KZM3 channel. Patch-clamping results showed that the inward K+ currents of maize guard cells were significantly increased in the KZM2 RNAi lines. In addition, the RNAi lines exhibited faster stomatal opening after light exposure. In conclusion, the presented results demonstrate that KZM2 functions as a negative regulator to modulate the Kin channels in maize guard cells. KZM2 and KZM3 may form heteromeric Kin channel and control stomatal opening in maize.
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Affiliation(s)
- Yong-Qiang Gao
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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19
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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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21
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Jozefkowicz C, Sigaut L, Scochera F, Soto G, Ayub N, Pietrasanta LI, Amodeo G, González Flecha FL, Alleva K. PIP Water Transport and Its pH Dependence Are Regulated by Tetramer Stoichiometry. Biophys J 2016; 110:1312-21. [PMID: 27028641 DOI: 10.1016/j.bpj.2016.01.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 12/28/2015] [Accepted: 01/19/2016] [Indexed: 01/27/2023] Open
Abstract
Many plasma membrane channels form oligomeric assemblies, and heterooligomerization has been described as a distinctive feature of some protein families. In the particular case of plant plasma membrane aquaporins (PIPs), PIP1 and PIP2 monomers interact to form heterotetramers. However, the biological properties of the different heterotetrameric configurations formed by PIP1 and PIP2 subunits have not been addressed yet. Upon coexpression of tandem PIP2-PIP1 dimers in Xenopus oocytes, we can address, for the first time to our knowledge, the functional properties of single heterotetrameric species having 2:2 stoichiometry. We have also coexpressed PIP2-PIP1 dimers with PIP1 and PIP2 monomers to experimentally investigate the localization and biological activity of each tetrameric assembly. Our results show that PIP2-PIP1 heterotetramers can assemble with 3:1, 1:3, or 2:2 stoichiometry, depending on PIP1 and PIP2 relative expression in the cell. All PIP2-PIP1 heterotetrameric species localize at the plasma membrane and present the same water transport capacity. Furthermore, the contribution of any heterotetrameric assembly to the total water transport through the plasma membrane doubles the contribution of PIP2 homotetramers. Our results also indicate that plasma membrane water transport can be modulated by the coexistence of different tetrameric species and by intracellular pH. Moreover, all the tetrameric species present similar cooperativity behavior for proton sensing. These findings throw light on the functional properties of PIP tetramers, showing that they have flexible stoichiometry dependent on the quantity of PIP1 and PIP2 molecules available. This represents, to our knowledge, a novel regulatory mechanism to adjust water transport across the plasma membrane.
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Affiliation(s)
- Cintia Jozefkowicz
- Instituto de Química y Fisicoquímica Biológica Alejandro C. Paladini (IQUIFIB), Universidad de Buenos Aires, Consejo National de Investigaciones Científicas y Técnicas (UBA-CONICET), Buenos Aires, Argentina
| | - Lorena Sigaut
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Física de Buenos Aires (IFIBA), CONICET, Ciudad Universitaria, Buenos Aires, Argentina
| | - Florencia Scochera
- Instituto de Química y Fisicoquímica Biológica Alejandro C. Paladini (IQUIFIB), Universidad de Buenos Aires, Consejo National de Investigaciones Científicas y Técnicas (UBA-CONICET), Buenos Aires, Argentina; Departamento de Fisicomatemática, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gabriela Soto
- Instituto de Genética Ewald A. Favret, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Argentina
| | - Nicolás Ayub
- Instituto de Genética Ewald A. Favret, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Argentina
| | - Lía Isabel Pietrasanta
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Física de Buenos Aires (IFIBA), CONICET, Ciudad Universitaria, Buenos Aires, Argentina; Centro de Microscopías Avanzadas, Facultad de Ciencias Exactas y Naturales, UBA-CONICET, Buenos Aires, Argentina
| | - Gabriela Amodeo
- Departamento de Biodiversidad y Biología Experimental, Instituto de Biodiversidad y Biología Experimental y Aplicada, Facultad de Ciencias Exactas y Naturales, UBA-CONICET, Buenos Aires, Argentina
| | - F Luis González Flecha
- Instituto de Química y Fisicoquímica Biológica Alejandro C. Paladini (IQUIFIB), Universidad de Buenos Aires, Consejo National de Investigaciones Científicas y Técnicas (UBA-CONICET), Buenos Aires, Argentina
| | - Karina Alleva
- Instituto de Química y Fisicoquímica Biológica Alejandro C. Paladini (IQUIFIB), Universidad de Buenos Aires, Consejo National de Investigaciones Científicas y Técnicas (UBA-CONICET), Buenos Aires, Argentina; Departamento de Fisicomatemática, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
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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. [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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23
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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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24
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Kleist TJ, Luan S. Constant change: dynamic regulation of membrane transport by calcium signalling networks keeps plants in tune with their environment. PLANT, CELL & ENVIRONMENT 2016; 39:467-481. [PMID: 26139029 DOI: 10.1111/pce.12599] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 05/20/2015] [Accepted: 05/21/2015] [Indexed: 06/04/2023]
Abstract
Despite substantial variation and irregularities in their environment, plants must conform to spatiotemporal demands on the molecular composition of their cytosol. Cell membranes are the major interface between organisms and their environment and the basis for controlling the contents and intracellular organization of the cell. Membrane transport proteins (MTPs) govern the flow of molecules across membranes, and their activities are closely monitored and regulated by cell signalling networks. By continuously adjusting MTP activities, plants can mitigate the effects of environmental perturbations, but effective implementation of this strategy is reliant on precise coordination among transport systems that reside in distinct cell types and membranes. Here, we examine the role of calcium signalling in the coordination of membrane transport, with an emphasis on potassium transport. Potassium is an exceptionally abundant and mobile ion in plants, and plant potassium transport has been intensively studied for decades. Classic and recent studies have underscored the importance of calcium in plant environmental responses and membrane transport regulation. In reviewing recent advances in our understanding of the coding and decoding of calcium signals, we highlight established and emerging roles of calcium signalling in coordinating membrane transport among multiple subcellular locations and distinct transport systems in plants, drawing examples from the CBL-CIPK signalling network. By synthesizing classical studies and recent findings, we aim to provide timely insights on the role of calcium signalling networks in the modulation of membrane transport and its importance in plant environmental responses.
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Affiliation(s)
- Thomas J Kleist
- University of California, Berkeley, Department of Plant & Microbial Biology, Berkeley, CA, 94720, USA
| | - Sheng Luan
- University of California, Berkeley, Department of Plant & Microbial Biology, Berkeley, CA, 94720, USA
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Safiarian MJ, Pertl-Obermeyer H, Lughofer P, Hude R, Bertl A, Obermeyer G. Lost in traffic? The K(+) channel of lily pollen, LilKT1, is detected at the endomembranes inside yeast cells, tobacco leaves, and lily pollen. FRONTIERS IN PLANT SCIENCE 2015; 6:47. [PMID: 25713578 PMCID: PMC4322604 DOI: 10.3389/fpls.2015.00047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 01/16/2015] [Indexed: 05/26/2023]
Abstract
Fertilization in plants relies on fast growth of pollen tubes through the style tissue toward the ovules. This polarized growth depends on influx of ions and water to increase the tube's volume. K(+) inward rectifying channels were detected in many pollen species, with one identified in Arabidopsis. Here, an Arabidopsis AKT1-like channel (LilKT1) was identified from Lilium longiflorum pollen. Complementation of K(+) uptake deficient yeast mutants was only successful when the entire LilKT1 C-terminus was replaced by the AKT1 C-terminus. No signals were observed in the plasma membrane (PM) of pollen tubes after expression of fluorescence-tagged LilKT1 nor were any LilKT1-derived peptides detectable in the pollen PM by mass spectrometry analysis. In contrast, fluorescent LilKT1 partly co-localized with the lily PM H(+) ATPase LilHA2 in the PM of tobacco leaf cells, but exhibited a punctual fluorescence pattern and also sub-plasma membrane localization. Thus, incorporation of LilKT1 into the pollen PM seems tighter controlled than in other cells with still unknown trafficking signals in LilKT1's C-terminus, resulting in channel densities below detection limits. This highly controlled incorporation might have physiological reasons: an uncontrolled number of K(+) inward channels in the pollen PM will give an increased water influx due to the raising cytosolic K(+) concentration, and finally, causing the tube to burst.
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Affiliation(s)
- Minou J. Safiarian
- Molecular Plant Biophysics and Biochemistry, Department of Molecular Biology, University of SalzburgSalzburg, Austria
| | - Heidi Pertl-Obermeyer
- Molecular Plant Biophysics and Biochemistry, Department of Molecular Biology, University of SalzburgSalzburg, Austria
- Plant Systems Biology, University of HohenheimStuttgart, Germany
| | - Peter Lughofer
- Molecular Plant Biophysics and Biochemistry, Department of Molecular Biology, University of SalzburgSalzburg, Austria
| | - Rene Hude
- Molecular Plant Biophysics and Biochemistry, Department of Molecular Biology, University of SalzburgSalzburg, Austria
| | - Adam Bertl
- Yeast Membrane Biology, Department of Biology, Darmstadt University of TechnologyDarmstadt, Germany
| | - Gerhard Obermeyer
- Molecular Plant Biophysics and Biochemistry, Department of Molecular Biology, University of SalzburgSalzburg, Austria
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Daras G, Rigas S, Tsitsekian D, Iacovides TA, Hatzopoulos P. Potassium transporter TRH1 subunits assemble regulating root-hair elongation autonomously from the cell fate determination pathway. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 231:131-7. [PMID: 25575998 DOI: 10.1016/j.plantsci.2014.11.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 11/24/2014] [Accepted: 11/28/2014] [Indexed: 05/17/2023]
Abstract
Trichoblasts of trh1 plants form root-hair initiation sites that fail to undergo tip growth resulting in a tiny root-hair phenotype. TRH1 belongs to Arabidopsis KT/KUP/HAK potassium transporter family controlling root-hair growth and gravitropism. Double mutant combinations between trh1 and root-hair mutants affecting cell fate or root-hair initiation exhibited additive phenotypes, suggesting that TRH1 acts independently and developmentally downstream of root-hair initiation. Bimolecular Fluorescence Complementation (BiFC), upon TRH1-YFP(C) and TRH1-YFP(N) co-transformation into tobacco epidermal cells, led to fluorescence emission indicative of TRH1 subunit homodimerization. Yeast two-hybrid analysis revealed two types of interactions. The hydrophilic segment between the second and the third transmembrane domain extending from residues Q105 to T141 is competent for a relatively weak interaction, whereas the region at the C-terminal beyond the last transmembrane domain, extending from amino acids R565 to A729, strongly self-interacts. These domains likely facilitate the co-assembly of TRH1 subunits forming an active K(+) transport system within cellular membrane structures. The results support the role of TRH1 acting as a convergence point between the developmental root-hair pathway and the environmental/hormonal signaling pathway to preserve auxin homeostasis ensuring plant adaptation in changing environments.
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Affiliation(s)
- Gerasimos Daras
- Department of Biotechnology, Agricultural University of Athens, Iera Odos 75,118 55, Athens, Greece.
| | - Stamatis Rigas
- Department of Biotechnology, Agricultural University of Athens, Iera Odos 75,118 55, Athens, Greece.
| | - Dikran Tsitsekian
- Department of Biotechnology, Agricultural University of Athens, Iera Odos 75,118 55, Athens, Greece.
| | - Tefkros A Iacovides
- Department of Biotechnology, Agricultural University of Athens, Iera Odos 75,118 55, Athens, Greece.
| | - Polydefkis Hatzopoulos
- Department of Biotechnology, Agricultural University of Athens, Iera Odos 75,118 55, Athens, Greece.
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Kollist H, Nuhkat M, Roelfsema MRG. Closing gaps: linking elements that control stomatal movement. THE NEW PHYTOLOGIST 2014; 203:44-62. [PMID: 24800691 DOI: 10.1111/nph.12832] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 03/27/2014] [Indexed: 05/18/2023]
Abstract
Stomata are an attractive experimental system in plant biology, because the responses of guard cells to environmental signals can be directly linked to changes in the aperture of stomatal pores. In this review, the mechanics of stomatal movement are discussed in relation to ion transport in guard cells. Emphasis is placed on the ion pumps, transporters, and channels in the plasma membrane, as well as in the vacuolar membrane. The biophysical properties of transport proteins for H(+), K(+), Ca(2+), and anions are discussed and related to their function in guard cells during stomatal movements. Guard cell signaling pathways for ABA, CO2, ozone, microbe-associated molecular patterns (MAMPs) and blue light are presented. Special attention is given to the regulation of the slow anion channel (SLAC) and SLAC homolog (SLAH)-type anion channels by the ABA signalosome. Over the last decade, several knowledge gaps in the regulation of ion transport in guard cells have been closed. The current state of knowledge is an excellent starting point for tackling important open questions concerning stress tolerance in plants.
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Affiliation(s)
- Hannes Kollist
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia
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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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Nieves-Cordones M, Alemán F, Martínez V, Rubio F. K+ uptake in plant roots. The systems involved, their regulation and parallels in other organisms. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:688-95. [PMID: 24810767 DOI: 10.1016/j.jplph.2013.09.021] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 09/26/2013] [Accepted: 09/28/2013] [Indexed: 05/20/2023]
Abstract
Potassium (K(+)) is an essential macronutrient for plants. It is taken into the plant by the transport systems present in the plasma membranes of root epidermal and cortical cells. The identity of these systems and their regulation is beginning to be understood and the systems of K(+) transport in the model species Arabidopsis thaliana remain far better characterized than in any other plant species. Roots can activate different K(+) uptake systems to adapt to their environment, important to a sessile organism that needs to cope with a highly variable environment. The mechanisms of K(+) acquisition in the model species A. thaliana are the best characterized at the molecular level so far. According to the current model, non-selective channels are probably the main pathways for K(+) uptake at high concentrations (>10mM), while at intermediate concentrations (1mM), the inward rectifying channel AKT1 dominates K(+) uptake. Under lower concentrations of external K(+) (100μM), AKT1 channels, together with the high-affinity K(+) uptake system HAK5 contribute to K(+) acquisition, and at extremely low concentrations (<10μM) the only system capable of taking up K(+) is HAK5. Depending on the species the high-affinity system has been named HAK5 or HAK1, but in all cases it fulfills the same functions. The activation of these systems as a function of the K(+) availability is achieved by different mechanisms that include phosphorylation of AKT1 or induction of HAK5 transcription. Some of the characteristics of the systems for root K(+) uptake are shared by other organisms, whilst others are specific to plants. This indicates that some crucial properties of the ancestral of K(+) transport systems have been conserved through evolution while others have diverged among different kingdoms.
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Affiliation(s)
| | - Fernando Alemán
- Departamento de Nutrición Vegetal, CEBAS-CSIC, Campus de Espinardo, Murcia 30100, Spain
| | - Vicente Martínez
- Departamento de Nutrición Vegetal, CEBAS-CSIC, Campus de Espinardo, Murcia 30100, Spain
| | - Francisco Rubio
- Departamento de Nutrición Vegetal, CEBAS-CSIC, Campus de Espinardo, Murcia 30100, Spain.
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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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31
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Xu J, Tian X, Egrinya Eneji A, Li Z. Functional characterization of GhAKT1, a novel Shaker-like K⁺ channel gene involved in K⁺ uptake from cotton (Gossypium hirsutum). Gene 2014; 545:61-71. [PMID: 24802116 DOI: 10.1016/j.gene.2014.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/16/2014] [Accepted: 05/02/2014] [Indexed: 10/25/2022]
Abstract
Shaker-like potassium (K(+)) channels in plants play an important role in K(+) absorption and transport. In this study, we characterized a Shaker-like K(+) channel gene GhAKT1 from the roots of Gossypium hirsutum cv. Liaomian17. Phylogenetic analysis showed that the GhAKT1 belongs to the AKT1-subfamily in the Shaker-like K(+) channel family. Confocal imaging of a GhAKT1-green fluorescent fusion protein (GFP) in transgenic Arabidopsis plants indicated that GhAKT1 is localized in the plasma membrane. Transcript analysis located GhAKT1 predominantly in cotton leaves with low abundance in roots, stem and shoot apex. Similarly, β-glucuronidase (GUS) activity was detected in both leaves and roots of PGhAKT1::GUS transgenic Arabidopsis plants. In roots, the GUS signals appeared in the epidermis, cortex and endodermis and root hairs, suggesting the contribution of GhAKT1 to K(+) uptake. In leaves, GhAKT1 was expressed in differentiated leaf primordial as well as mesophyll cells and veins of expanded leaves, pointing to its involvement in cell elongation and K(+) transport and distribution in leaves. Severe K(+) deficiency did not affect the expression of GhAKT1 gene. GhAKT1-overexpression in either the Arabidopsis wild-type or akt1 mutant enhanced the growth of transgenic seedlings under low K(+) deficiency and raised the net K(+) influx in roots at 100μM external K(+) concentration, within the range of operation of the high-affinity K(+) uptake system. The application of 2mM BaCl2 resulted in net K(+) efflux in roots, and eliminated the differences between GhAKT1-overexpression lines and their acceptors indicating that the K(+) uptake mediated by GhAKT1 is also as Ba(2+)-sensitive as AtAKT1.
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Affiliation(s)
- Juan Xu
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Agronomy, China Agricultural University, Beijing 100193, China
| | - Xiaoli Tian
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Agronomy, China Agricultural University, Beijing 100193, China.
| | - A Egrinya Eneji
- Department of Soil Science, Faculty of Agriculture, Forestry and Wildlife Resources Management, University of Calabar, Nigeria
| | - Zhaohu Li
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Agronomy, China Agricultural University, Beijing 100193, China
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32
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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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Chérel I, Lefoulon C, Boeglin M, Sentenac H. Molecular mechanisms involved in plant adaptation to low K(+) availability. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:833-48. [PMID: 24293613 DOI: 10.1093/jxb/ert402] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Potassium is a major inorganic constituent of the living cell and the most abundant cation in the cytosol. It plays a role in various functions at the cell level, such as electrical neutralization of anionic charges, protein synthesis, long- and short-term control of membrane polarization, and regulation of the osmotic potential. Through the latter function, K(+) is involved at the whole-plant level in osmotically driven functions such as cell movements, regulation of stomatal aperture, or phloem transport. Thus, plant growth and development require that large amounts of K(+) are taken up from the soil and translocated to the various organs. In most ecosystems, however, soil K(+) availability is low and fluctuating, so plants have developed strategies to take up K(+) more efficiently and preserve vital functions and growth when K(+) availability is becoming limited. These strategies include increased capacity for high-affinity K(+) uptake from the soil, K(+) redistribution between the cytosolic and vacuolar pools, ensuring cytosolic homeostasis, and modification of root system development and architecture. Our knowledge about the mechanisms and signalling cascades involved in these different adaptive responses has been rapidly growing during the last decade, revealing a highly complex network of interacting processes. This review is focused on the different physiological responses induced by K(+) deprivation, their underlying molecular events, and the present knowledge and hypotheses regarding the mechanisms responsible for K(+) sensing and signalling.
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Affiliation(s)
- Isabelle Chérel
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France
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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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38
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Abstract
As one of the most important mineral nutrient elements, potassium (K(+)) participates in many plant physiological processes and determines the yield and quality of crop production. In this review, we summarize K(+) signaling processes and K(+) transport regulation in higher plants, especially in plant responses to K(+)-deficiency stress. Plants perceive external K(+) fluctuations and generate the initial K(+) signal in root cells. This signal is transduced into the cytoplasm and encoded as Ca(2+) and reactive oxygen species signaling. K(+)-deficiency-induced signals are subsequently decoded by cytoplasmic sensors, which regulate the downstream transcriptional and posttranslational responses. Eventually, plants produce a series of adaptive events in both physiological and morphological alterations that help them survive K(+) deficiency.
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Affiliation(s)
- Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry, National Center of Plant Gene Research (Beijing), College of Biological Sciences, China Agricultural University, Beijing 100193, China
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39
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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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40
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Rocchetti A, Sharma T, Wulfetange C, Scholz-Starke J, Grippa A, Carpaneto A, Dreyer I, Vitale A, Czempinski K, Pedrazzini E. The putative K(+) channel subunit AtKCO3 forms stable dimers in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2012; 3:251. [PMID: 23162563 PMCID: PMC3495302 DOI: 10.3389/fpls.2012.00251] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 10/22/2012] [Indexed: 05/20/2023]
Abstract
The permeation pore of K(+) channels is formed by four copies of the pore domain. AtKCO3 is the only putative voltage-independent K(+) channel subunit of Arabidopsis thaliana with a single pore domain. KCO3-like proteins recently emerged in evolution and, to date, have been found only in the genus Arabidopsis (A. thaliana and A. lyrata). We show that the absence of KCO3 does not cause marked changes in growth under various conditions. Only under osmotic stress we observed reduced root growth of the kco3-1 null-allele line. This phenotype was complemented by expressing a KCO3 mutant with an inactive pore, indicating that the function of KCO3 under osmotic stress does not depend on its direct ability to transport ions. Constitutively overexpressed AtKCO3 or AtKCO3::GFP are efficiently sorted to the tonoplast indicating that the protein is approved by the endoplasmic reticulum quality control. However, vacuoles isolated from transgenic plants do not have significant alterations in current density. Consistently, both AtKCO3 and AtKCO3::GFP are detected as homodimers upon velocity gradient centrifugation, an assembly state that would not allow for activity. We conclude that if AtKCO3 ever functions as a K(+) channel, active tetramers are held by particularly weak interactions, are formed only in unknown specific conditions and may require partner proteins.
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Affiliation(s)
- Alessandra Rocchetti
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle RicercheMilano, Italy
- Alessandra Rocchetti and Tripti Sharma have contributed equally to the work
| | - Tripti Sharma
- Institute of Biochemistry and Biology, University of PotsdamPotsdam-Golm, Germany
- Alessandra Rocchetti and Tripti Sharma have contributed equally to the work
| | - Camilla Wulfetange
- Institute of Biochemistry and Biology, University of PotsdamPotsdam-Golm, Germany
| | | | - Alexandra Grippa
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle RicercheMilano, Italy
| | - Armando Carpaneto
- Istituto di Biofisica, Consiglio Nazionale delle RicercheGenova, Italy
| | - Ingo Dreyer
- Institute of Biochemistry and Biology, University of PotsdamPotsdam-Golm, Germany
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de MadridMadrid, Spain
| | - Alessandro Vitale
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle RicercheMilano, Italy
| | - Katrin Czempinski
- Institute of Biochemistry and Biology, University of PotsdamPotsdam-Golm, Germany
| | - Emanuela Pedrazzini
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle RicercheMilano, Italy
- *Correspondence: Emanuela Pedrazzini, Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, via Bassini 15, 20133 Milano, Italy. e-mail:
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41
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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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43
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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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44
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Wang Y, He L, Li HD, Xu J, Wu WH. Potassium channel α-subunit AtKC1 negatively regulates AKT1-mediated K+ uptake in Arabidopsis roots under low-K+ stress. Cell Res 2010; 20:826-37. [DOI: 10.1038/cr.2010.74] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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45
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Abstract
Potassium (K(+)) is one of the essential macronutrients for plant growth and development. However, K(+) content in soils is usually limited so that the crop yields are restricted. Plants may adapt to K(+)-deficient environment by adjusting their physiological and morphological status, indicating that plants may have evolved their sensing and signaling mechanisms in response to K(+)-deficiency. This short review particularly discusses some components as possible sensors or signal transducers involved in plant sensing and signaling in response to K(+)-deficiency, such as K(+) channels and transporters, H(+)-ATPase, some cytoplasmic enzymes, etc. Possible involvement of Ca²(+) and ROS signals in plant responses to K(+)-deficiency is also discussed.
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Affiliation(s)
- Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), National Plant Gene Research Centre (Beijing), College of Biological Sciences, China Agricultural University, Beijing 100193, China
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46
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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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47
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Ion Channels and Plant Stress: Past, Present, and Future. ION CHANNELS AND PLANT STRESS RESPONSES 2010. [DOI: 10.1007/978-3-642-10494-7_1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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48
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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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49
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Honsbein A, Sokolovski S, Grefen C, Campanoni P, Pratelli R, Paneque M, Chen Z, Johansson I, Blatt MR. A tripartite SNARE-K+ channel complex mediates in channel-dependent K+ nutrition in Arabidopsis. THE PLANT CELL 2009; 21:2859-77. [PMID: 19794113 PMCID: PMC2768940 DOI: 10.1105/tpc.109.066118] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 07/28/2009] [Accepted: 09/03/2009] [Indexed: 05/17/2023]
Abstract
A few membrane vesicle trafficking (SNARE) proteins in plants are associated with signaling and transmembrane ion transport, including control of plasma membrane ion channels. Vesicle traffic contributes to the population of ion channels at the plasma membrane. Nonetheless, it is unclear whether these SNAREs also interact directly to affect channel gating and, if so, what functional impact this might have on the plant. Here, we report that the Arabidopsis thaliana SNARE SYP121 binds to KC1, a regulatory K(+) channel subunit that assembles with different inward-rectifying K(+) channels to affect their activities. We demonstrate that SYP121 interacts preferentially with KC1 over other Kv-like K(+) channel subunits and that KC1 interacts specifically with SYP121 but not with its closest structural and functional homolog SYP122 nor with another related SNARE SYP111. SYP121 promoted gating of the inward-rectifying K(+) channel AKT1 but only when heterologously coexpressed with KC1. Mutation in any one of the three genes, SYP121, KC1, and AKT1, selectively suppressed the inward-rectifying K(+) current in Arabidopsis root epidermal protoplasts as well as K(+) acquisition and growth in seedlings when channel-mediated K(+) uptake was limiting. That SYP121 should be important for gating of a K(+) channel and its role in inorganic mineral nutrition demonstrates an unexpected role for SNARE-ion channel interactions, apparently divorced from signaling and vesicle traffic. Instead, it suggests a role in regulating K(+) uptake coordinately with membrane expansion for cell growth.
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50
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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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