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Kunz HH, Armbruster U, Mühlbauer S, de Vries J, Davis GA. Chloroplast ion homeostasis - what do we know and where should we go? THE NEW PHYTOLOGIST 2024. [PMID: 38515227 DOI: 10.1111/nph.19661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 02/01/2024] [Indexed: 03/23/2024]
Abstract
Plant yields heavily depend on proper macro- and micronutrient supply from the soil. In the leaf cells, nutrient ions fulfill specific roles in biochemical reactions, especially photosynthesis housed in the chloroplast. Here, a well-balanced ion homeostasis is maintained by a number of ion transport proteins embedded in the envelope and thylakoid membranes. Ten years ago, the first alkali metal transporters from the K+ EFFLUX ANTIPORTER family were discovered in the model plant Arabidopsis. Since then, our knowledge about the physiological importance of these carriers and their substrates has greatly expanded. New insights into the role of alkali ions in plastid gene expression and photoprotective mechanisms, both prerequisites for plant productivity in natural environments, were gained. The discovery of a Cl- channel in the thylakoid and several additional plastid alkali and alkali metal transport proteins have advanced the field further. Nevertheless, scientists still have long ways to go before a complete systemic understanding of the chloroplast's ion transportome will emerge. In this Tansley review, we highlight and discuss the achievements of the last decade. More importantly, we make recommendations on what areas to prioritize, so the field can reach the next milestones. One area, laid bare by our similarity-based comparisons among phototrophs is our lack of knowledge what ion transporters are used by cyanobacteria to buffer photosynthesis fluctuations.
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Affiliation(s)
- Hans-Henning Kunz
- Plant Biochemistry, Biology, LMU Munich, Großhadernerstr. 2-4, 82152, Planegg-Martinsried, Germany
| | - Ute Armbruster
- Institute of Molecular Photosynthesis, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
- CEPLAS - Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
| | - Susanne Mühlbauer
- Plant Biochemistry, Biology, LMU Munich, Großhadernerstr. 2-4, 82152, Planegg-Martinsried, Germany
| | - Jan de Vries
- Department of Applied Bioinformatics, Institute for Microbiology and Genetics, Goettingen Center for Molecular Biosciences (GZMB), Campus Institute Data Science (CIDAS), University of Goettingen, Goldschmidtstr. 1, D-37077, Göttingen, Germany
| | - Geoffry A Davis
- Plant Biochemistry, Biology, LMU Munich, Großhadernerstr. 2-4, 82152, Planegg-Martinsried, Germany
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
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2
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Kuntz M, Dimnet L, Pullara S, Moyet L, Rolland N. The Main Functions of Plastids. Methods Mol Biol 2024; 2776:89-106. [PMID: 38502499 DOI: 10.1007/978-1-0716-3726-5_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Plastids are semi-autonomous organelles like mitochondria and derive from a cyanobacterial ancestor that was engulfed by a host cell. During evolution, they have recruited proteins originating from the nuclear genome, and only parts of their ancestral metabolic properties were conserved and optimized to limit functional redundancy with other cell compartments. Furthermore, large disparities in metabolic functions exist among various types of plastids, and the characterization of their various metabolic properties is far from being accomplished. In this review, we provide an overview of the main functions, known to be achieved by plastids or shared by plastids and other compartments of the cell. In short, plastids appear at the heart of all main plant functions.
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Affiliation(s)
- Marcel Kuntz
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRAE, Univ. Grenoble Alpes, IRIG, CEA Grenoble, Grenoble, France.
| | - Laura Dimnet
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRAE, Univ. Grenoble Alpes, IRIG, CEA Grenoble, Grenoble, France
| | - Sara Pullara
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRAE, Univ. Grenoble Alpes, IRIG, CEA Grenoble, Grenoble, France
| | - Lucas Moyet
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRAE, Univ. Grenoble Alpes, IRIG, CEA Grenoble, Grenoble, France
| | - Norbert Rolland
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRAE, Univ. Grenoble Alpes, IRIG, CEA Grenoble, Grenoble, France
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3
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Fukuda Y, Ishiyama C, Kawai-Yamada M, Hashida SN. Adjustment of light-responsive NADP dynamics in chloroplasts by stromal pH. Nat Commun 2023; 14:7148. [PMID: 37932304 PMCID: PMC10628217 DOI: 10.1038/s41467-023-42995-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 10/26/2023] [Indexed: 11/08/2023] Open
Abstract
Cyclic electron transfer (CET) predominates when NADP+ is at basal levels, early in photosynthetic induction; however, the mechanism underlying the subsequent supply of NADP+ to fully drive steady-state linear electron transfer remains unclear. Here, we investigated whether CET is involved in de novo NADP+ supply in Arabidopsis thaliana and measured chloroplastic NADP dynamics to evaluate responsiveness to variable light, photochemical inhibitors, darkness, and CET activity. The sum of oxidized and reduced forms shows that levels of NADP and NAD increase and decrease, respectively, in response to light; levels of NADP and NAD decrease and increase in the dark, respectively. Moreover, consistent with the pH change in the stroma, the pH preference of chloroplast NAD+ phosphorylation and NADP+ dephosphorylation is alkaline and weakly acidic, respectively. Furthermore, CET is correlated with upregulation of light-responsive NADP level increases and downregulation of dark-responsive NADP level reductions. These findings are consistent with CET helping to regulate NADP pool size via stromal pH regulation under fluctuating light conditions.
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Affiliation(s)
- Yusuke Fukuda
- Civil Engineering Research & Environmental Studies (CERES), Inc., 1646, Abiko, Chiba, 270-1194, Japan
| | - Chinami Ishiyama
- Civil Engineering Research & Environmental Studies (CERES), Inc., 1646, Abiko, Chiba, 270-1194, Japan
| | - Maki Kawai-Yamada
- Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Shin-Nosuke Hashida
- Sustainable System Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646, Abiko, Chiba, 270-1194, Japan.
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Kreis E, König K, Misir M, Niemeyer J, Sommer F, Schroda M. TurboID reveals the proxiomes of Chlamydomonas proteins involved in thylakoid biogenesis and stress response. PLANT PHYSIOLOGY 2023; 193:1772-1796. [PMID: 37310689 PMCID: PMC10602608 DOI: 10.1093/plphys/kiad335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 04/24/2023] [Accepted: 05/04/2023] [Indexed: 06/14/2023]
Abstract
In Chlamydomonas (Chlamydomonas reinhardtii), the VESICLE-INDUCING PROTEIN IN PLASTIDS 1 and 2 (VIPP1 and VIPP2) play roles in the sensing and coping with membrane stress and in thylakoid membrane biogenesis. To gain more insight into these processes, we aimed to identify proteins interacting with VIPP1/2 in the chloroplast and chose proximity labeling (PL) for this purpose. We used the transient interaction between the nucleotide exchange factor CHLOROPLAST GRPE HOMOLOG 1 (CGE1) and the stromal HEAT SHOCK PROTEIN 70B (HSP70B) as test system. While PL with APEX2 and BioID proved to be inefficient, TurboID resulted in substantial biotinylation in vivo. TurboID-mediated PL with VIPP1/2 as baits under ambient and H2O2 stress conditions confirmed known interactions of VIPP1 with VIPP2, HSP70B, and the CHLOROPLAST DNAJ HOMOLOG 2 (CDJ2). Proteins identified in the VIPP1/2 proxiomes can be grouped into proteins involved in the biogenesis of thylakoid membrane complexes and the regulation of photosynthetic electron transport, including PROTON GRADIENT REGULATION 5-LIKE 1 (PGRL1). A third group comprises 11 proteins of unknown function whose genes are upregulated under chloroplast stress conditions. We named them VIPP PROXIMITY LABELING (VPL). In reciprocal experiments, we confirmed VIPP1 in the proxiomes of VPL2 and PGRL1. Our results demonstrate the robustness of TurboID-mediated PL for studying protein interaction networks in the chloroplast of Chlamydomonas and pave the way for analyzing functions of VIPPs in thylakoid biogenesis and stress responses.
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Affiliation(s)
- Elena Kreis
- Molekulare Biotechnologie & Systembiologie, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 23, D-67663 Kaiserslautern, Germany
| | - Katharina König
- Molekulare Biotechnologie & Systembiologie, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 23, D-67663 Kaiserslautern, Germany
| | - Melissa Misir
- Molekulare Biotechnologie & Systembiologie, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 23, D-67663 Kaiserslautern, Germany
| | - Justus Niemeyer
- Molekulare Biotechnologie & Systembiologie, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 23, D-67663 Kaiserslautern, Germany
| | - Frederik Sommer
- Molekulare Biotechnologie & Systembiologie, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 23, D-67663 Kaiserslautern, Germany
| | - Michael Schroda
- Molekulare Biotechnologie & Systembiologie, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 23, D-67663 Kaiserslautern, Germany
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Bulychev AA, Shapiguzov SY, Alova AV. Electrical Signals at the Plasma Membrane and Their Influence on Chlorophyll Fluorescence of Chara Chloroplasts in vivo. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1455-1466. [PMID: 38105017 DOI: 10.1134/s0006297923100048] [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: 05/31/2023] [Revised: 06/30/2023] [Accepted: 07/02/2023] [Indexed: 12/19/2023]
Abstract
Action potentials of plant cells are engaged in the regulation of many cell processes, including photosynthesis and cytoplasmic streaming. Excitable cells of characean algae submerged in a medium with an elevated K+ content are capable of generating hyperpolarizing electrical responses. These active responses of plasma membrane originate upon the passage of inward electric current comparable in strength to natural currents circulating in illuminated Chara internodes. So far, it remained unknown whether the hyperpolarizing electrical signals in Chara affect the photosynthetic activity. Here, we showed that the negative shift of cell membrane potential, which drives K+ influx into the cytoplasm, is accompanied by a delayed decrease in the actual yield of chlorophyll fluorescence F' and the maximal fluorescence yield Fm' under low background light (12.5 µmol m-2 s-1). The transient changes in F' and Fm' were evident only under illumination, which suggests their close relation to the photosynthetic energy conversion in chloroplasts. Passing the inward current caused an increase in pH at the cell surface (pHo), which reflected high H+/OH- conductance of the plasmalemma and indicated a decrease in cytoplasmic pH due to the H+ entry into the cell. The shifts in pHo arising in response to the first hyperpolarizing pulse disappeared upon repeated stimulation, thus indicating the long-term inactivation of plasmalemmal H+/OH- conductance. Suppression of plasmalemmal H+ fluxes did not abolish the hyperpolarizing responses and the analyzed changes in chlorophyll fluorescence. These results suggest that K+ fluxes between the extracellular medium, cytoplasm, and stroma are involved in the functional changes of chloroplasts reflected by transients of F' and Fm'.
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Affiliation(s)
| | | | - Anna V Alova
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
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Zhang X, Wang L, Pan T, Wu X, Shen J, Jiang L, Tajima H, Blumwald E, Qiu QS. Plastid KEA-type cation/H + antiporters are required for vacuolar protein trafficking in Arabidopsis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:2157-2174. [PMID: 37252889 DOI: 10.1111/jipb.13537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 05/28/2023] [Indexed: 06/01/2023]
Abstract
Arabidopsis plastid antiporters KEA1 and KEA2 are critical for plastid development, photosynthetic efficiency, and plant development. Here, we show that KEA1 and KEA2 are involved in vacuolar protein trafficking. Genetic analyses found that the kea1 kea2 mutants had short siliques, small seeds, and short seedlings. Molecular and biochemical assays showed that seed storage proteins were missorted out of the cell and the precursor proteins were accumulated in kea1 kea2. Protein storage vacuoles (PSVs) were smaller in kea1 kea2. Further analyses showed that endosomal trafficking in kea1 kea2 was compromised. Vacuolar sorting receptor 1 (VSR1) subcellular localizations, VSR-cargo interactions, and p24 distribution on the endoplasmic reticulum (ER) and Golgi apparatus were affected in kea1 kea2. Moreover, plastid stromule growth was reduced and plastid association with the endomembrane compartments was disrupted in kea1 kea2. Stromule growth was regulated by the cellular pH and K+ homeostasis maintained by KEA1 and KEA2. The organellar pH along the trafficking pathway was altered in kea1 kea2. Overall, KEA1 and KEA2 regulate vacuolar trafficking by controlling the function of plastid stromules via adjusting pH and K+ homeostasis.
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Affiliation(s)
- Xiao Zhang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 73000, China
- Academy of Plateau Science and Sustainability, School of Life Sciences, Qinghai Normal University, Xining, 810000, China
- College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, China
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, 730000, China
| | - Lu Wang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 73000, China
- Academy of Plateau Science and Sustainability, School of Life Sciences, Qinghai Normal University, Xining, 810000, China
- College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, China
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, 730000, China
| | - Ting Pan
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 73000, China
| | - Xuexia Wu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 73000, China
| | - Jinbo Shen
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, 311300, China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China
| | - Hiromi Tajima
- Department of Plant Sciences, University of California, Davis, CA, 95616, USA
| | - Eduardo Blumwald
- Department of Plant Sciences, University of California, Davis, CA, 95616, USA
| | - Quan-Sheng Qiu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 73000, China
- Academy of Plateau Science and Sustainability, School of Life Sciences, Qinghai Normal University, Xining, 810000, China
- College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, China
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, 730000, China
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Rasmussen T. The Potassium Efflux System Kef: Bacterial Protection against Toxic Electrophilic Compounds. MEMBRANES 2023; 13:membranes13050465. [PMID: 37233526 DOI: 10.3390/membranes13050465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 04/21/2023] [Accepted: 04/23/2023] [Indexed: 05/27/2023]
Abstract
Kef couples the potassium efflux with proton influx in gram-negative bacteria. The resulting acidification of the cytosol efficiently prevents the killing of the bacteria by reactive electrophilic compounds. While other degradation pathways for electrophiles exist, Kef is a short-term response that is crucial for survival. It requires tight regulation since its activation comes with the burden of disturbed homeostasis. Electrophiles, entering the cell, react spontaneously or catalytically with glutathione, which is present at high concentrations in the cytosol. The resulting glutathione conjugates bind to the cytosolic regulatory domain of Kef and trigger activation while the binding of glutathione keeps the system closed. Furthermore, nucleotides can bind to this domain for stabilization or inhibition. The binding of an additional ancillary subunit, called KefF or KefG, to the cytosolic domain is required for full activation. The regulatory domain is termed K+ transport-nucleotide binding (KTN) or regulator of potassium conductance (RCK) domain, and it is also found in potassium uptake systems or channels in other oligomeric arrangements. Bacterial RosB-like transporters and K+ efflux antiporters (KEA) of plants are homologs of Kef but fulfill different functions. In summary, Kef provides an interesting and well-studied example of a highly regulated bacterial transport system.
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Affiliation(s)
- Tim Rasmussen
- Rudolf Virchow Center and Biocenter, Institute of Biochemistry II, Julius-Maximilians-Universität Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
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Photosynthetic acclimation to changing environments. Biochem Soc Trans 2023; 51:473-486. [PMID: 36892145 DOI: 10.1042/bst20211245] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/03/2023] [Accepted: 02/21/2023] [Indexed: 03/10/2023]
Abstract
Plants are exposed to environments that fluctuate of timescales varying from seconds to months. Leaves that develop in one set of conditions optimise their metabolism to the conditions experienced, in a process called developmental acclimation. However, when plants experience a sustained change in conditions, existing leaves will also acclimate dynamically to the new conditions. Typically this process takes several days. In this review, we discuss this dynamic acclimation process, focussing on the responses of the photosynthetic apparatus to light and temperature. We briefly discuss the principal changes occurring in the chloroplast, before examining what is known, and not known, about the sensing and signalling processes that underlie acclimation, identifying likely regulators of acclimation.
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Zheng S, Su M, Shi Z, Gao H, Ma C, Zhu S, Zhang L, Wu G, Wu W, Wang J, Zhang J, Zhang T. Exogenous sucrose influences KEA1 and KEA2 to regulate abscisic acid-mediated primary root growth in Arabidopsis. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 317:111209. [PMID: 35193734 DOI: 10.1016/j.plantsci.2022.111209] [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: 11/04/2021] [Revised: 01/24/2022] [Accepted: 02/03/2022] [Indexed: 06/14/2023]
Abstract
Arabidopsis K+-efflux antiporter (KEA)1 and KEA2 are chloroplast inner envelope membrane K+/H+ antiporters that play an important role in plastid development and seedling growth. However, the function of KEA1 and KEA2 during early seedling development is poorly understood. In this work, we found that in Arabidopsis, KEA1 and KEA2 mediated primary root growth by regulating photosynthesis and the ABA signaling pathway. Phenotypic analyses revealed that in the absence of sucrose, the primary root length of the kea1kea2 mutant was significantly shorter than that of the wild-type Columbia-0 (Col-0) plant. However, this phenotype could be remedied by the external application of sucrose. Meanwhile, HPLC-MS/MS results showed that in sucrose-free medium, ABA accumulation in the kea1kea2 mutant was considerably lower than that in Col-0. Transcriptome analysis revealed that many key genes involved in ABA signals were repressed in the kea1kea2 mutant. We concluded that KEA1 and KEA2 deficiency not only affected photosynthesis but was also involved in primary root growth likely through an ABA-dependent manner. This study confirmed the new function of KEA1 and KEA2 in affecting primary root growth.
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Affiliation(s)
- Sheng Zheng
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China; Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining 810016, China.
| | - Min Su
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Zhongfei Shi
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Haixia Gao
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Cheng Ma
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Shan Zhu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China
| | - Lina Zhang
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Guofan Wu
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Wangze Wu
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Juan Wang
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Jinping Zhang
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
| | - Tengguo Zhang
- College of Life Sciences, Northwest Normal University, Lanzhou 730070, China.
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Trinh MDL, Masuda S. Chloroplast pH Homeostasis for the Regulation of Photosynthesis. FRONTIERS IN PLANT SCIENCE 2022; 13:919896. [PMID: 35693183 PMCID: PMC9174948 DOI: 10.3389/fpls.2022.919896] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 05/04/2022] [Indexed: 05/16/2023]
Abstract
The pH of various chloroplast compartments, such as the thylakoid lumen and stroma, is light-dependent. Light illumination induces electron transfer in the photosynthetic apparatus, coupled with proton translocation across the thylakoid membranes, resulting in acidification and alkalization of the thylakoid lumen and stroma, respectively. Luminal acidification is crucial for inducing regulatory mechanisms that protect photosystems against photodamage caused by the overproduction of reactive oxygen species (ROS). Stromal alkalization activates enzymes involved in the Calvin-Benson-Bassham (CBB) cycle. Moreover, proton translocation across the thylakoid membranes generates a proton gradient (ΔpH) and an electric potential (ΔΨ), both of which comprise the proton motive force (pmf) that drives ATP synthase. Then, the synthesized ATP is consumed in the CBB cycle and other chloroplast metabolic pathways. In the dark, the pH of both the chloroplast stroma and thylakoid lumen becomes neutral. Despite extensive studies of the above-mentioned processes, the molecular mechanisms of how chloroplast pH can be maintained at proper levels during the light phase for efficient activation of photosynthesis and other metabolic pathways and return to neutral levels during the dark phase remain largely unclear, especially in terms of the precise control of stromal pH. The transient increase and decrease in chloroplast pH upon dark-to-light and light-to-dark transitions have been considered as signals for controlling other biological processes in plant cells. Forward and reverse genetic screening approaches recently identified new plastid proteins involved in controlling ΔpH and ΔΨ across the thylakoid membranes and chloroplast proton/ion homeostasis. These proteins have been conserved during the evolution of oxygenic phototrophs and include putative photosynthetic protein complexes, proton transporters, and/or their regulators. Herein, we summarize the recently identified protein players that control chloroplast pH and influence photosynthetic efficiency in plants.
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Affiliation(s)
- Mai Duy Luu Trinh
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Shinji Masuda
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
- *Correspondence: Shinji Masuda,
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Azeem F, Zameer R, Rehman Rashid MA, Rasul I, Ul-Allah S, Siddique MH, Fiaz S, Raza A, Younas A, Rasool A, Ali MA, Anwar S, Siddiqui MH. Genome-wide analysis of potassium transport genes in Gossypium raimondii suggest a role of GrHAK/KUP/KT8, GrAKT2.1 and GrAKT1.1 in response to abiotic stress. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 170:110-122. [PMID: 34864561 DOI: 10.1016/j.plaphy.2021.11.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 06/13/2023]
Abstract
Potassium (K+) is an important macro-nutrient for plants, which comprises almost 10% of plant's dry mass. It plays a crucial role in the growth of plants as well as other important processes related to metabolism and stress tolerance. Plants have a complex and well-organized potassium distribution system (channels and transporters). Cotton is the most important economic crop, which is the primary source of natural fiber. Soil deficiency in K+ can negatively affect yield and fiber quality of cotton. However, potassium transport system in cotton is poorly studied. Current study identified 43 Potassium Transport System (PTS) genes in Gossypium raimondii genome. Based on conserved domains, transmembrane domains, and motif structures, these genes were classified as K+ transporters (2 HKTs, 7 KEAs, and 16 KUP/HAK/KTs) and K+ channels (11 Shakers and 7 TPKs/KCO). The phylogenetic comparison of GrPTS genes from Arabidopsis thaliana, Glycine max, Oryza sativa, Medicago truncatula and Cicer arietinum revealed variations in PTS gene conservation. Evolutionary analysis predicted that most GrPTS genes were segmentally duplicated. Gene structure analysis showed that the intron/exon organization of these genes was conserved in specific-family. Chromosomal localization demonstrated a random distribution of PTS genes across all the thirteen chromosomes except chromosome six. Many stress responsive cis-regulatory elements were predicted in promoter regions of GrPTS genes. The RNA-seq data analysis followed by qRT-PCR validation demonstrated that PTS genes potentially work in groups against environmental factors. Moreover, a transporter gene (GrHAK/KUP/KT8) and two channel genes (GrAKT2.1 and GrAKT1.1) are important candidate genes for plant stress response. These results provide useful information for further functional characterization of PTS genes with the breeding aim of stress-resistant cultivars.
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Affiliation(s)
- Farrukh Azeem
- Department of Bioinformatics and Biotechnology, Govt. College University, Faisalabad, Pakistan
| | - Roshan Zameer
- Department of Bioinformatics and Biotechnology, Govt. College University, Faisalabad, Pakistan
| | | | - Ijaz Rasul
- Department of Bioinformatics and Biotechnology, Govt. College University, Faisalabad, Pakistan
| | - Sami Ul-Allah
- College of Agriculture, Bahauddin Zakariya University, Bahadur Sub-Campus, Layyah, Pakistan
| | | | - Sajid Fiaz
- Department of Plant Breeding and Genetics, The University of Haripur, 22620, Haripir, Pakistan.
| | - Ali Raza
- Fujian Provincial Key Laboratory of Crop Molecular and Cell Biology, Oil Crops Research Institute, Center of Legume Crop Genetics and Systems Biology/College of Agriculture, Fujian Agriculture and Forestry University (FAFU), Fuzhou, Fujian, 350002, China
| | - Afifa Younas
- Department of Botany, Lahore College for Women University, Lahore, Pakistan
| | - Asima Rasool
- Department of Bioinformatics and Biotechnology, Govt. College University, Faisalabad, Pakistan
| | - Muhammad Amjad Ali
- Department of Plant Pathology, University of Agriculture, Faisalabad, Pakistan
| | - Sultana Anwar
- Department of Agronomy, University of Florida, Gainesville, USA
| | - Manzer H Siddiqui
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
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Völkner C, Holzner LJ, Day PM, Ashok AD, de Vries J, Bölter B, Kunz HH. Two plastid POLLUX ion channel-like proteins are required for stress-triggered stromal Ca2+release. PLANT PHYSIOLOGY 2021; 187:2110-2125. [PMID: 34618095 PMCID: PMC8644588 DOI: 10.1093/plphys/kiab424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Two decades ago, large cation currents were discovered in the envelope membranes of Pisum sativum L. (pea) chloroplasts. The deduced K+-permeable channel was coined fast-activating chloroplast cation channel but its molecular identity remained elusive. To reveal candidates, we mined proteomic datasets of isolated pea envelopes. Our search uncovered distant members of the nuclear POLLUX ion channel family. Since pea is not amenable to molecular genetics, we used Arabidopsis thaliana to characterize the two gene homologs. Using several independent approaches, we show that both candidates localize to the chloroplast envelope membrane. The proteins, designated PLASTID ENVELOPE ION CHANNELS (PEC1/2), form oligomers with regulator of K+ conductance domains protruding into the intermembrane space. Heterologous expression of PEC1/2 rescues yeast mutants deficient in K+ uptake. Nuclear POLLUX ion channels cofunction with Ca2+ channels to generate Ca2+ signals, critical for establishing mycorrhizal symbiosis and root development. Chloroplasts also exhibit Ca2+ transients in the stroma, probably to relay abiotic and biotic cues between plastids and the nucleus via the cytosol. Our results show that pec1pec2 loss-of-function double mutants fail to trigger the characteristic stromal Ca2+ release observed in wild-type plants exposed to external stress stimuli. Besides this molecular abnormality, pec1pec2 double mutants do not show obvious phenotypes. Future studies of PEC proteins will help to decipher the plant's stress-related Ca2+ signaling network and the role of plastids. More importantly, the discovery of PECs in the envelope membrane is another critical step towards completing the chloroplast ion transport protein inventory.
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Affiliation(s)
- Carsten Völkner
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Lorenz Josef Holzner
- Department of Plant Biochemistry, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Philip M Day
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Amra Dhabalia Ashok
- Department of Applied Bioinformatics, University of Goettingen, Institute for Microbiology and Genetics, 37077 Göttingen,Germany
- International Max Planck Research School for Genome Science, 37077 Göttingen, Germany
| | - Jan de Vries
- Department of Applied Bioinformatics, University of Goettingen, Institute for Microbiology and Genetics, 37077 Göttingen,Germany
- International Max Planck Research School for Genome Science, 37077 Göttingen, Germany
- Applied Bioinformatics, Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, Göttingen,Germany
- Campus Institute Data Science (CIDAS), University of Goettingen, 37077 Göttingen, Germany
| | - Bettina Bölter
- Department of Plant Biochemistry, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Hans-Henning Kunz
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
- Department of Plant Biochemistry, LMU Munich, 82152 Planegg-Martinsried, Germany
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Homecoming: rewinding the reductive evolution of the chloroplast genome for increasing crop yields. Nat Commun 2021; 12:6734. [PMID: 34795241 PMCID: PMC8602674 DOI: 10.1038/s41467-021-26975-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/28/2021] [Indexed: 11/29/2022] Open
Abstract
Developing more productive and sustainable crops will be essential to achieving food security in coming decades. A core process in plant evolution has been the transfer of chloroplast-encoded genes to the nuclear genome. We propose reverting this process as a new approach to improve plant disease resistance and photosynthesis in future crops.
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DeTar RA, Barahimipour R, Manavski N, Schwenkert S, Höhner R, Bölter B, Inaba T, Meurer J, Zoschke R, Kunz HH. Loss of inner-envelope K+/H+ exchangers impairs plastid rRNA maturation and gene expression. THE PLANT CELL 2021; 33:2479-2505. [PMID: 34235544 PMCID: PMC8364240 DOI: 10.1093/plcell/koab123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/30/2021] [Indexed: 05/08/2023]
Abstract
The inner-envelope K+ EFFLUX ANTIPORTERS (KEA) 1 and 2 are critical for chloroplast development, ion homeostasis, and photosynthesis. However, the mechanisms by which changes in ion flux across the envelope affect organelle biogenesis remained elusive. Chloroplast development requires intricate coordination between the nuclear genome and the plastome. Many mutants compromised in plastid gene expression (PGE) display a virescent phenotype, that is delayed greening. The phenotypic appearance of Arabidopsis thaliana kea1 kea2 double mutants fulfills this criterion, yet a link to PGE has not been explored. Here, we show that a simultaneous loss of KEA1 and KEA2 results in maturation defects of the plastid ribosomal RNAs. This may be caused by secondary structure changes of rRNA transcripts and concomitant reduced binding of RNA-processing proteins, which we documented in the presence of skewed ion homeostasis in kea1 kea2. Consequently, protein synthesis and steady-state levels of plastome-encoded proteins remain low in mutants. Disturbance in PGE and other signs of plastid malfunction activate GENOMES UNCOUPLED 1-dependent retrograde signaling in kea1 kea2, resulting in a dramatic downregulation of GOLDEN2-LIKE transcription factors to halt expression of photosynthesis-associated nuclear-encoded genes (PhANGs). PhANG suppression delays the development of fully photosynthesizing kea1 kea2 chloroplasts, probably to avoid progressing photo-oxidative damage. Overall, our results reveal that KEA1/KEA2 function impacts plastid development via effects on RNA-metabolism and PGE.
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Affiliation(s)
- Rachael Ann DeTar
- Plant Physiology, School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA
| | - Rouhollah Barahimipour
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Nikolay Manavski
- Plant Sciences, Department I, LMU Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Serena Schwenkert
- Plant Sciences, Department I, LMU Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Ricarda Höhner
- Plant Physiology, School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA
| | - Bettina Bölter
- Plant Sciences, Department I, LMU Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Takehito Inaba
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Jörg Meurer
- Plant Sciences, Department I, LMU Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Reimo Zoschke
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Hans-Henning Kunz
- Plant Physiology, School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA
- Plant Sciences, Department I, LMU Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
- Author for correspondence:
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15
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Kameoka T, Okayasu T, Kikuraku K, Ogawa T, Sawa Y, Yamamoto H, Ishikawa T, Maruta T. Cooperation of chloroplast ascorbate peroxidases and proton gradient regulation 5 is critical for protecting Arabidopsis plants from photo-oxidative stress. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 107:876-892. [PMID: 34028907 DOI: 10.1111/tpj.15352] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 05/24/2023]
Abstract
High-light (HL) stress enhances the production of H2 O2 from the photosynthetic electron transport chain in chloroplasts, potentially causing photo-oxidative damage. Although stromal and thylakoid membrane-bound ascorbate peroxidases (sAPX and tAPX, respectively) are major H2 O2 -scavenging enzymes in chloroplasts, their knockout mutants do not exhibit a visible phenotype under HL stress. Trans-thylakoid proton gradient (∆pH)-dependent mechanisms exist for controlling H2 O2 production from photosynthesis, such as thermal dissipation of light energy and downregulation of electron transfer between photosystems II and I, and these may compensate for the lack of APXs. To test this hypothesis, we focused on a proton gradient regulation 5 (pgr5) mutant, wherein both ∆pH-dependent mechanisms are impaired, and an Arabidopsis sapx tapx double mutant was crossed with the pgr5 single mutant. The sapx tapx pgr5 triple mutant exhibited extreme sensitivity to HL compared with its parental lines. This phenotype was consistent with cellular redox perturbations and enhanced expression of many oxidative stress-responsive genes. These findings demonstrate that the PGR5-dependent mechanisms compensate for chloroplast APXs, and vice versa. An intriguing finding was that the failure of induction of non-photochemical quenching in pgr5 (because of the limitation in ∆pH formation) was partially recovered in sapx tapx pgr5. Further genetic studies suggested that this recovery was dependent on the NADH dehydrogenase-like complex-dependent pathway for cyclic electron flow around photosystem I. Together with data from the sapx tapx npq4 mutant, we discuss the interrelationship between APXs and ∆pH-dependent mechanisms under HL stress.
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Affiliation(s)
- Takashi Kameoka
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Takaya Okayasu
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Kana Kikuraku
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori, 680-8553, Japan
| | - Takahisa Ogawa
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori, 680-8553, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Yoshihiro Sawa
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Hiroshi Yamamoto
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Takahiro Ishikawa
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori, 680-8553, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Takanori Maruta
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori, 680-8553, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
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