1
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Wegener M, Persicke M, Dietz KJ. Reprogramming the translatome during daily light transitions as affected by cytosolic glyceraldehyde-3-phosphate dehydrogenases GAPC1/C2. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:2494-2509. [PMID: 38156667 DOI: 10.1093/jxb/erad509] [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: 08/14/2023] [Accepted: 12/27/2023] [Indexed: 01/03/2024]
Abstract
Dark-light and light-dark transitions during the day are switching points of leaf metabolism that strongly affect the regulatory state of the cells, and this change is hypothesized to affect the translatome. The cytosolic glyceraldehyde-3-phosphate dehydrogenases GAPC1 and GAPC2 function in glycolysis, and carbohydrate and energy metabolism, but GAPC1/C2 also shows moonlighting functions in gene expression and post-transcriptional regulation. In this study we examined the rapid reprogramming of the translatome that occurs within 10 min at the end of the night and the end of the day in wild-type (WT) Arabidopsis and a gapc1/c2 double-knockdown mutant. Metabolite profiling compared to the WT showed that gapc1/c2 knockdown led to increases in a set of metabolites at the start of day, particularly intermediates of the citric acid cycle and linked pathways. Differences in metabolite changes were also detected at the end of the day. Only small sets of transcripts changed in the total RNA pool; however, RNA-sequencing revealed major alterations in polysome-associated transcripts at the light-transition points. The most pronounced difference between the WT and gapc1/c2 was seen in the reorganization of the translatome at the start of the night. Our results are in line with the proposed hypothesis that GAPC1/C2 play a role in the control of the translatome during light/dark transitions.
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Affiliation(s)
- Melanie Wegener
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Universitätsstr.25, D-33615, Bielefeld, Germany
| | - Marcus Persicke
- Center for Biotechnology-CeBiTec, Bielefeld University, Universitätsstr. 27, D-33615 Bielefeld, Germany
| | - Karl-Josef Dietz
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Universitätsstr.25, D-33615, Bielefeld, Germany
- Center for Biotechnology-CeBiTec, Bielefeld University, Universitätsstr. 27, D-33615 Bielefeld, Germany
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2
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Zheng Q, Hu J, Tan Q, Hu H, Sun C, Lei K, Tian Z, Dai T. Improved chloroplast Pi allocation helps sustain electron transfer to enhance photosynthetic low-phosphorus tolerance of wheat. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 201:107880. [PMID: 37437346 DOI: 10.1016/j.plaphy.2023.107880] [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: 04/04/2023] [Revised: 06/24/2023] [Accepted: 07/05/2023] [Indexed: 07/14/2023]
Abstract
Phosphorus (P) deficit limits high wheat (Triticum aestivum L.) yields. Breeding low-P-tolerant cultivars is vital for sustainable agriculture and food security, but the low-P adaptation mechanisms are largely not understood. Two wheat cultivars, ND2419 (low-P-tolerant) and ZM366 (low-P-sensitive) were used in this study. They were grown under hydroponic conditions with low-P (0.015 mM) or normal-P (1 mM). Low-P suppressed biomass accumulation and net photosynthetic rate (A) in both cultivars, whereas ND2419 was relatively less suppressed. Intercellular CO2 concentration did not decrease with the decline of stomatal conductance. Additionally, maximum electron transfer rate (Jmax) decreased sooner than maximum carboxylation rate (Vcmax). Results indicate that impeded electron transfer is directly responsible for decreased A. Under low-P, ND2419 exhibited greater PSII functionality (potential activity (Fv/Fo), maximum quantum efficiency (Fv/Fm), photochemical quenching (qL) and non-photochemical quenching (NPQ) required for electron transfer than ZM366, resulting more ATP for Rubisco activation. Furthermore, ND2419 maintained higher chloroplast Pi concentrations by enhancing chloroplast Pi allocation, compared with ZM366. Overall, the low-P-tolerant cultivar sustained electron transfer under low-P by enhancing chloroplast Pi allocation, allowing more ATP synthesis for Rubisco activation, ultimately presenting stronger photosynthesis capacities. The improved chloroplasts Pi allocation may provide new insights into improve low-P tolerance.
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Affiliation(s)
- Qiaomei Zheng
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Jinling Hu
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Qingwen Tan
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Hang Hu
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Chuanjiao Sun
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Kangqi Lei
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Zhongwei Tian
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Tingbo Dai
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
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Barlow AN, Manu MS, Saladi SM, Tarr PT, Yadav Y, Thinn AMM, Zhu Y, Laganowsky AD, Clemons WM, Ramasamy S. Structures of Get3d reveal a distinct architecture associated with the emergence of photosynthesis. J Biol Chem 2023; 299:104752. [PMID: 37100288 PMCID: PMC10248533 DOI: 10.1016/j.jbc.2023.104752] [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: 02/16/2023] [Revised: 04/16/2023] [Accepted: 04/21/2023] [Indexed: 04/28/2023] Open
Abstract
Homologs of the protein Get3 have been identified in all domains yet remain to be fully characterized. In the eukaryotic cytoplasm, Get3 delivers tail-anchored (TA) integral membrane proteins, defined by a single transmembrane helix at their C terminus, to the endoplasmic reticulum. While most eukaryotes have a single Get3 gene, plants are notable for having multiple Get3 paralogs. Get3d is conserved across land plants and photosynthetic bacteria and includes a distinctive C-terminal α-crystallin domain. After tracing the evolutionary origin of Get3d, we solve the Arabidopsis thaliana Get3d crystal structure, identify its localization to the chloroplast, and provide evidence for a role in TA protein binding. The structure is identical to that of a cyanobacterial Get3 homolog, which is further refined here. Distinct features of Get3d include an incomplete active site, a "closed" conformation in the apo-state, and a hydrophobic chamber. Both homologs have ATPase activity and are capable of binding TA proteins, supporting a potential role in TA protein targeting. Get3d is first found with the development of photosynthesis and conserved across 1.2 billion years into the chloroplasts of higher plants across the evolution of photosynthesis suggesting a role in the homeostasis of photosynthetic machinery.
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Affiliation(s)
- Alexandra N Barlow
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - M S Manu
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, India
| | - Shyam M Saladi
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - Paul T Tarr
- Howard Hughes Medical Institute and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Yashpal Yadav
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, India
| | - Aye M M Thinn
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - Yun Zhu
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | | | - William M Clemons
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA.
| | - Sureshkumar Ramasamy
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, India.
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4
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Zhang P, Guo X, Gao J, Liu H, Wan C, Li J, Zhang Q, Song Y, Ding C. A Dual-Control Strategy by Phosphate Ions and Local Microviscosity for Tracking Adenosine Triphosphate Metabolism in Mitochondria and Cellular Activity Dynamically. ACS Sens 2021; 6:4225-4233. [PMID: 34709795 DOI: 10.1021/acssensors.1c01850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Adenosine triphosphate (ATP) acts as the main energy source for growth and development in organisms, and the disorder reflects the mitochondrial damage to a large extent. Therefore, an efficient tool for the evaluation of the ATP metabolic level is important to track mitochondrial health, providing an additional perspective for an in-depth long-term study on living activities. Herein, a twisted intramolecular charge transfer (TICT) framework is utilized to build up a sensitive receptor, Mito-VP, with a negligible background to target mitochondrial ATP metabolism by monitoring the phosphate ion (Pi) level upon ATP hydrolysis under the overall consideration of the structural and functional features of mitochondria. The responsive fluorescence could be lighted on under the dual control of Pi and local microviscosity, and the two steps of ATP hydrolysis could be captured through fluorescence. In addition to the well-behaved mitochondrial targeting, the energy metabolism at cellular and organism levels has been clarified via mitosis and zebrafish development, respectively.
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Affiliation(s)
- Peng Zhang
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Xinjie Guo
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Jian Gao
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Haihong Liu
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Chenyang Wan
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Jiajia Li
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Qian Zhang
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Yuqing Song
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
| | - Caifeng Ding
- Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science, MOE, Shandong Key Laboratory of Biochemical Analysis, Key Laboratory of Analytical Chemistry for Life Science in Universities of Shandong, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
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5
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Kleczkowski LA, Igamberdiev AU. Magnesium Signaling in Plants. Int J Mol Sci 2021; 22:1159. [PMID: 33503839 PMCID: PMC7865908 DOI: 10.3390/ijms22031159] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 01/16/2021] [Accepted: 01/19/2021] [Indexed: 01/02/2023] Open
Abstract
Free magnesium (Mg2+) is a signal of the adenylate (ATP+ADP+AMP) status in the cells. It results from the equilibrium of adenylate kinase (AK), which uses Mg-chelated and Mg-free adenylates as substrates in both directions of its reaction. The AK-mediated primary control of intracellular [Mg2+] is finely interwoven with the operation of membrane-bound adenylate- and Mg2+-translocators, which in a given compartment control the supply of free adenylates and Mg2+ for the AK-mediated equilibration. As a result, [Mg2+] itself varies both between and within the compartments, depending on their energetic status and environmental clues. Other key nucleotide-utilizing/producing enzymes (e.g., nucleoside diphosphate kinase) may also be involved in fine-tuning of the intracellular [Mg2+]. Changes in [Mg2+] regulate activities of myriads of Mg-utilizing/requiring enzymes, affecting metabolism under both normal and stress conditions, and impacting photosynthetic performance, respiration, phloem loading and other processes. In compartments controlled by AK equilibrium (cytosol, chloroplasts, mitochondria, nucleus), the intracellular [Mg2+] can be calculated from total adenylate contents, based on the dependence of the apparent equilibrium constant of AK on [Mg2+]. Magnesium signaling, reflecting cellular adenylate status, is likely widespread in all eukaryotic and prokaryotic organisms, due simply to the omnipresent nature of AK and to its involvement in adenylate equilibration.
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Affiliation(s)
- Leszek A. Kleczkowski
- Department of Plant Physiology, Umeå Plant Science Centre, University of Umeå, 901 87 Umeå, Sweden
| | - Abir U. Igamberdiev
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL A1B3X9, Canada;
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6
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Bellasio C. A generalised dynamic model of leaf-level C 3 photosynthesis combining light and dark reactions with stomatal behaviour. PHOTOSYNTHESIS RESEARCH 2019; 141:99-118. [PMID: 30471008 DOI: 10.1007/s11120-018-0601-1] [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: 03/16/2018] [Accepted: 10/27/2018] [Indexed: 05/16/2023]
Abstract
Global food demand is rising, impelling us to develop strategies for improving the efficiency of photosynthesis. Classical photosynthesis models based on steady-state assumptions are inherently unsuitable for assessing biochemical and stomatal responses to rapid variations in environmental drivers. To identify strategies to increase photosynthetic efficiency, we need models that account for the timing of CO2 assimilation responses to dynamic environmental stimuli. Herein, I present a dynamic process-based photosynthetic model for C3 leaves. The model incorporates both light and dark reactions, coupled with a hydro-mechanical model of stomatal behaviour. The model achieved a stable and realistic rate of light-saturated CO2 assimilation and stomatal conductance. Additionally, it replicated complete typical assimilatory response curves (stepwise change in CO2 and light intensity at different oxygen levels) featuring both short lag times and full photosynthetic acclimation. The model also successfully replicated transient responses to changes in light intensity (light flecks), CO2 concentration, and atmospheric oxygen concentration. This dynamic model is suitable for detailed ecophysiological studies and has potential for superseding the long-dominant steady-state approach to photosynthesis modelling. The model runs as a stand-alone workbook in Microsoft® Excel® and is freely available to download along with a video tutorial.
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Affiliation(s)
- Chandra Bellasio
- Research School of Biology, Australian National University, Acton, ACT, 2601, Australia.
- University of the Balearic Islands, 07122, Palma, Illes Balears, Spain.
- Trees and Timber Institute, National Research Council of Italy, Sesto Fiorentino, 50019, Florence, Italy.
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7
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Gao J, Wang F, Sun J, Tian Z, Hu H, Jiang S, Luo Q, Xu Y, Jiang D, Cao W, Dai T. Enhanced Rubisco activation associated with maintenance of electron transport alleviates inhibition of photosynthesis under low nitrogen conditions in winter wheat seedlings. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:5477-5488. [PMID: 30239847 DOI: 10.1093/jxb/ery315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 09/03/2018] [Indexed: 06/08/2023]
Abstract
Studying the response of photosynthesis to low nitrogen (N) and the underlying physiological mechanism can provide a theoretical basis for breeding N-efficient cultivars and optimizing N management. We conducted hydroponic experiments using two wheat (Triticum aestivum) cultivars, Zaoyangmai (low N sensitive) and Yangmai158 (low N tolerant), with either 0.25 mM N as a low N (LN) treatment or 5 mM N as a control. Under LN, a decrease in net photosynthetic rate (Pn) was attributed to reduction in the maximum Rubisco carboxylation rate, which then accelerated a reduction in the maximum ribulose-1,5-bisphosphate regeneration rate, and the reduction in Pn was 5-35% less in Yangmai158 than in Zaoyangmai. Yangmai158 maintained a 10-25% higher Rubisco concentration, especially in the upper leaves, and up-regulated Rubisco activase activity compared with Zaoyangmai to increase the Rubisco activation to sustain Rubisco carboxylation under LN conditions. In addition, Yangmai158 increased electron flux to the photorespiratory carbon oxidation cycle and alternative electron flux to maintain a faster electron transport rate and avoid photodamage. In conclusion, the LN-tolerant cultivar showed enhanced Rubisco activation and sustained electron transport to maintain a greater photosynthetic capacity under LN conditions.
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Affiliation(s)
- Jingwen Gao
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Feng Wang
- Center of Excellence for Soil Biology, College of Resources and Environment, Southwest University, Beibei, Chongqing, P. R. China
| | - Jianyun Sun
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Zhongwei Tian
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Hang Hu
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Suyu Jiang
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Qiuci Luo
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Yun Xu
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Dong Jiang
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Weixing Cao
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
| | - Tingbo Dai
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, P. R. China
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8
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Takagi D, Amako K, Hashiguchi M, Fukaki H, Ishizaki K, Goh T, Fukao Y, Sano R, Kurata T, Demura T, Sawa S, Miyake C. Chloroplastic ATP synthase builds up a proton motive force preventing production of reactive oxygen species in photosystem I. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 91:306-324. [PMID: 28380278 DOI: 10.1111/tpj.13566] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 03/29/2017] [Accepted: 04/03/2017] [Indexed: 05/19/2023]
Abstract
Over-reduction of the photosynthetic electron transport (PET) chain should be avoided, because the accumulation of reducing electron carriers produces reactive oxygen species (ROS) within photosystem I (PSI) in thylakoid membranes and causes oxidative damage to chloroplasts. To prevent production of ROS in thylakoid membranes the H+ gradient (ΔpH) needs to be built up across the thylakoid membranes to suppress the over-reduction state of the PET chain. In this study, we aimed to identify the critical component that stimulates ΔpH formation under illumination in higher plants. To do this, we screened ethyl methane sulfonate (EMS)-treated Arabidopsis thaliana, in which the formation of ΔpH is impaired and the PET chain caused over-reduction under illumination. Subsequently, we isolated an allelic mutant that carries a missense mutation in the γ-subunit of chloroplastic CF0 CF1 -ATP synthase, named hope2. We found that hope2 suppressed the formation of ΔpH during photosynthesis because of the high H+ efflux activity from the lumenal to stromal side of the thylakoid membranes via CF0 CF1 -ATP synthase. Furthermore, PSI was in a more reduced state in hope2 than in wild-type (WT) plants, and hope2 was more vulnerable to PSI photoinhibition than WT under illumination. These results suggested that chloroplastic CF0 CF1 -ATP synthase adjusts the redox state of the PET chain, especially for PSI, by modulating H+ efflux activity across the thylakoid membranes. Our findings suggest the importance of the buildup of ΔpH depending on CF0 CF1 -ATP synthase to adjust the redox state of the reaction center chlorophyll P700 in PSI and to suppress the production of ROS in PSI during photosynthesis.
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Affiliation(s)
- Daisuke Takagi
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
- Core Research for Environmental Science and Technology, Japan Science and Technology Agency, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076, Japan
| | - Katsumi Amako
- Faculty of Nutrition, Kobe Gakuin University, Kobe, 651-2180, Japan
| | - Masaki Hashiguchi
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Hidehiro Fukaki
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan
| | - Kimitsune Ishizaki
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan
| | - Tatsuaki Goh
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan
| | - Yoichiro Fukao
- Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Ikoma, 630-0192, Japan
| | - Ryosuke Sano
- Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Ikoma, 630-0192, Japan
| | - Tetsuya Kurata
- Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Ikoma, 630-0192, Japan
- Graduate School of Life Sciences, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, 980-8578, Japan
| | - Taku Demura
- Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), Ikoma, 630-0192, Japan
| | - Shinichiro Sawa
- Graduate School of Science and Technology, Kumamoto University, Kurokami, Tyuou-ku, Kumamoto, 860-8555, Japan
| | - Chikahiro Miyake
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
- Core Research for Environmental Science and Technology, Japan Science and Technology Agency, 7 Gobancho, Chiyoda-ku, Tokyo, 102-0076, Japan
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9
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Diensthuber RP, Tominaga M, Preller M, Hartmann FK, Orii H, Chizhov I, Oiwa K, Tsiavaliaris G. Kinetic mechanism of Nicotiana tabacum myosin-11 defines a new type of a processive motor. FASEB J 2015; 29:81-94. [PMID: 25326536 DOI: 10.1096/fj.14-254763] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The 175-kDa myosin-11 from Nicotiana tabacum (Nt(175kDa)myosin-11) is exceptional in its mechanical activity as it is the fastest known processive actin-based motor, moving 10 times faster than the structurally related class 5 myosins. Although this ability might be essential for long-range organelle transport within larger plant cells, the kinetic features underlying the fast processive movement of Nt(175kDa)myosin-11 still remain unexplored. To address this, we generated a single-headed motor domain construct and carried out a detailed kinetic analysis. The data demonstrate that Nt(175kDa)myosin-11 is a high duty ratio motor, which remains associated with actin most of its enzymatic cycle. However, different from other processive myosins that establish a high duty ratio on the basis of a rate-limiting ADP-release step, Nt(175kDa)myosin-11 achieves a high duty ratio by a prolonged duration of the ATP-induced isomerization of the actin-bound states and ADP release kinetics, both of which in terms of the corresponding time constants approach the total ATPase cycle time. Molecular modeling predicts that variations in the charge distribution of the actin binding interface might contribute to the thermodynamic fine-tuning of the kinetics of this myosin. Our study unravels a new type of a high duty ratio motor and provides important insights into the molecular mechanism of processive movement of higher plant myosins.
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Affiliation(s)
- Ralph P Diensthuber
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Motoki Tominaga
- Live Cell Molecular Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, Japan; Science and Technology Agency, PRESTO, Saitama, Japan
| | - Matthias Preller
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany; Centre for Structural Systems Biology, German Electron Synchrotron (DESY), Hamburg, Germany
| | - Falk K Hartmann
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Hidefumi Orii
- Graduate School of Life Science, University of Hyogo, Hyogo, Japan; and
| | - Igor Chizhov
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Kazuhiro Oiwa
- Graduate School of Life Science, University of Hyogo, Hyogo, Japan; and Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe, Japan
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10
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Nunes C, Primavesi LF, Patel MK, Martinez-Barajas E, Powers SJ, Sagar R, Fevereiro PS, Davis BG, Paul MJ. Inhibition of SnRK1 by metabolites: tissue-dependent effects and cooperative inhibition by glucose 1-phosphate in combination with trehalose 6-phosphate. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 63:89-98. [PMID: 23257075 DOI: 10.1016/j.plaphy.2012.11.011] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/15/2012] [Indexed: 05/02/2023]
Abstract
SnRK1 of the SNF1/AMPK group of protein kinases is an important regulatory protein kinase in plants. SnRK1 was recently shown as a target of the sugar signal, trehalose 6-phosphate (T6P). Glucose 6-phosphate (G6P) can also inhibit SnRK1 and given the similarity in structure to T6P, we sought to establish if each could impart distinct inhibition of SnRK1. Other central metabolites, glucose 1-phosphate (G1P), fructose 6-phosphate and UDP-glucose were also tested, and additionally ribose 5-phosphate (R5P), recently reported to inhibit SnRK1 strongly in wheat grain tissue. For the metabolites that inhibited SnRK1, kinetic models show that T6P, G1P and G6P each provide distinct regulation (50% inhibition of SnRK1 at 5.4 μM, 480 μM, >1 mM, respectively). Strikingly, G1P in combination with T6P inhibited SnRK1 synergistically. R5P, in contrast to the other inhibitors, inhibited SnRK1 in green tissues only. We show that this is due to consumption of ATP in the assay mediated by phosphoribulokinase during conversion of R5P to ribulose-1,5-bisphosphate. The accompanying loss of ATP limits the activity of SnRK1 giving rise to an apparent inhibition of SnRK1. Inhibition of SnRK1 by R5P in wheat grain preparations can be explained by the presence of green pericarp tissue; this exposes an important caveat in the assessment of potential protein kinase inhibitors. Data provide further insight into the regulation of SnRK1 by metabolites.
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Affiliation(s)
- Cátia Nunes
- Plant Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom
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11
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Heber U. From horse thief to professor: confessions of a plant physiologist. PHOTOSYNTHESIS RESEARCH 2012; 112:1-12. [PMID: 22399437 DOI: 10.1007/s11120-012-9725-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 02/03/2012] [Indexed: 05/31/2023]
Abstract
Can 50 years of research, performed between ignorance and the wish to know, and executed between hope, despair, satisfaction and pain, be compressed into an abstract? What has been done in more than 50 years may be expressed in four words: it was worth it. If I had another life, I would do it again. In the beginning of my career, life was an enigma. It still is. Molecular details of the workings of life had been largely unknown when I began. Now, at the end, I still wish to know details: how is light, master of life, manipulated to either support life, when photosynthesis is possible, or to protect it when light endangers it. What is the molecular and the physical nature of the biological mechanisms which control both, energy conservation and energy dissipation, in photosynthesis?
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Affiliation(s)
- Ulrich Heber
- Julius-von-Sachs-Institute, University of Würzburg, 97082 Würzburg, Germany.
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12
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Tcherkez G, Mahé A, Boex-Fontvieille E, Gout E, Guérard F, Bligny R. Experimental evidence of phosphoenolpyruvate resynthesis from pyruvate in illuminated leaves. PLANT PHYSIOLOGY 2011; 157:86-95. [PMID: 21730197 PMCID: PMC3165900 DOI: 10.1104/pp.111.180711] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 06/30/2011] [Indexed: 05/18/2023]
Abstract
Day respiration is the cornerstone of nitrogen assimilation since it provides carbon skeletons to primary metabolism for glutamate (Glu) and glutamine synthesis. However, recent studies have suggested that the tricarboxylic acid pathway is rate limiting and mitochondrial pyruvate dehydrogenation is partly inhibited in the light. Pyruvate may serve as a carbon source for amino acid (e.g. alanine) or fatty acid synthesis, but pyruvate metabolism is not well documented, and neither is the possible resynthesis of phosphoenolpyruvate (PEP). Here, we examined the capacity of pyruvate to convert back to PEP using (13)C and (2)H labeling in illuminated cocklebur (Xanthium strumarium) leaves. We show that the intramolecular labeling pattern in Glu, 2-oxoglutarate, and malate after (13)C-3-pyruvate feeding was consistent with (13)C redistribution from PEP via the PEP-carboxylase reaction. Furthermore, the deuterium loss in Glu after (2)H(3)-(13)C-3-pyruvate feeding suggests that conversion to PEP and back to pyruvate washed out (2)H atoms to the solvent. Our results demonstrate that in cocklebur leaves, PEP resynthesis occurred as a flux from pyruvate, approximately 0.5‰ of the net CO(2) assimilation rate. This is likely to involve pyruvate inorganic phosphate dikinase and the fundamental importance of this flux for PEP and inorganic phosphate homeostasis is discussed.
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Affiliation(s)
- Guillaume Tcherkez
- Institut de Biologie des Plantes, Centre National de la Recherche Scientifique Unité Mixte de Recherche 8618, France.
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Pärnik T, Ivanova H, Keerberg O. Photorespiratory and respiratory decarboxylations in leaves of C3 plants under different CO2 concentrations and irradiances. PLANT, CELL & ENVIRONMENT 2007; 30:1535-1544. [PMID: 17986155 DOI: 10.1111/j.1365-3040.2007.01725.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We used an advanced radiogasometric method to study the effects of short-term changes in CO2 concentration ([CO2]) on the rates and substrates of photorespiratory and respiratory decarboxylations under steady-state photosynthesis and in the dark. Experiments were carried out on Plantago lanceolata, Poa trivialis, Secale cereale, Triticum aestivum, Helianthus annuus and Arabidopsis thaliana plants. Rates of photorespiration and respiration measured at a low [CO2] (40 micromol mol(-1)) were equal to those at normal [CO2] (360 micromol mol(-1)). Under low [CO2], the substrates of decarboxylation reactions were derived mainly from stored photosynthates, while under normal [CO2] primary photosynthates were preferentially consumed. An increase in [CO2] from 320 to 2300 micromol mol(-1) brought about a fourfold decrease in the rate of photorespiration with a concomitant 50% increase in the rate of respiration in the light. Respiration in the dark did not depend on [CO2] up to 30 mmol mol(-1). A positive correlation was found between the rate of respiration in the dark and the rate of photosynthesis during the preceding light period. The respiratory decarboxylation of stored photosynthates was suppressed by light. The extent of light inhibition decreased with increasing [CO2]; no inhibition was detected at 30 mmol mol(-1) CO2.
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Affiliation(s)
- T Pärnik
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia
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14
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Ohmann E, Borriss R, Rindt KP. Glucose-6-phosphat-Dehydrogenase in autotrophen Mikroorganismen. II. Die Regulation der Aktivität der Glucose-6-phosphat-Dehydrogenase in Euglena gracilis und Rhodopseudomonas spheroides. J Basic Microbiol 2007. [DOI: 10.1002/jobm.19700100104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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15
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Mehta N, Panda A, Roy AS, Datta SN. Unique Rate Expression for Glucose Production in C4 Plants. J Phys Chem B 2007; 111:919-21. [PMID: 17266243 DOI: 10.1021/jp067758a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A physicochemical interpretation of a recently formulated temperature-dependent, steady-state rate expression for the production of glucose equivalent in C(4) plants is given here. We show that the rate equation is applicable to a wide range of C(4) plants.
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Preiss J. Regulation of adenosine diphosphate glucose pyrophosphorylase. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 46:317-81. [PMID: 345767 DOI: 10.1002/9780470122914.ch5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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17
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Cruz JA, Kanazawa A, Treff N, Kramer DM. Storage of light-driven transthylakoid proton motive force as an electric field (Deltapsi) under steady-state conditions in intact cells of Chlamydomonas reinhardtii. PHOTOSYNTHESIS RESEARCH 2005; 85:221-33. [PMID: 16075322 DOI: 10.1007/s11120-005-4731-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2004] [Accepted: 03/29/2005] [Indexed: 05/03/2023]
Abstract
Proton motive force (pmf) is physiologically stored as either a DeltapH or a membrane potential (Deltapsi) across bacterial and mitochondrial energetic membranes. In the case of chloroplasts, previous work (Cruz et al. 2001, Biochemistry 40: 1226-1237) indicates that Deltapsi is a significant fraction of pmf, in vivo, and in vitro as long as the activities of counterions are relatively low. Kinetic analysis of light-induced changes in the electrochromic shift (ECS) in intact leaves was consistent with these observations. In this work, we took advantage of the spectroscopic properties of the green alga, Chlamydomonas reinhardtii, to demonstrate that light-driven Deltapsi was stored in vivo over the hours time scale. Analysis of the light-induced ECS kinetics suggested that the steady-state Deltapsi in 400 micromol photons m(-2) s(-1) red light was between 20 and 90 mV and that this represented about 60% of the light-induced increase in pmf. By extrapolation, it was surmised that about half of total (basal and light-induced) pmf is held as Deltapsi. It is hypothesized that Deltapsi is stabilized either by maintaining low chloroplast ionic strength or by active membrane ion transporters. In addition to the strong implications for regulation of photosynthesis by the xanthophyll cycle, these results imply that pmf partitioning is important across a wide range of species.
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Affiliation(s)
- Jeffrey A Cruz
- Institute of Biological Chemistry, Washington State University, Pullman, 99164-6340, USA.
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18
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Igamberdiev AU, Kleczkowski LA. Membrane potential, adenylate levels and Mg2+ are interconnected via adenylate kinase equilibrium in plant cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1607:111-9. [PMID: 14670601 DOI: 10.1016/j.bbabio.2003.09.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Concentrations of adenylate species and free magnesium (Mg(2+)) within cells are mediated by the equilibrium governed by adenylate kinase (AK), the enzyme abundant in plants in chloroplast stroma and intermembrane spaces of chloroplasts and mitochondria. Ratios of free and Mg-bound adenylates (linked to the values of [Mg(2+)] established under AK equilibrium) can be rationalized in terms of the overall dependence of concentrations of Mg(2+) and free and Mg-bound adenylates, as well as electric potential values across the inner membranes of mitochondria and chloroplasts. The potential across the inner mitochondrial membrane, by driving adenylate translocators, equilibrates free adenylates across the inner membrane according to the Nernst equation and contributes to the ATP(total)/ADP(total) ratio in the cytosol. The ratio affects the exchange of free adenylates with chloroplasts and this, in turn, influences the value of potential across the inner chloroplast membrane. From measurements of subcellular ATP(total)/ADP(total) ratios, we suggest a method of estimating the values of potential across inner membranes of mitochondria and chloroplasts in vivo, which allows a comparison of the operation of these organelles under different physiological conditions. We discuss also how the equilibration of adenylates by AK drives adenylate transport across membranes, and establishes [Mg(2+)] in the cytosol and chloroplast stroma, maintaining the rates of photosynthesis and respiration. This provides a tool for metabolomic research, by which the determined concentrations of adenylate species could be used for computation of essential metabolic parameters in the cell and in subcellular compartments.
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Affiliation(s)
- Abir U Igamberdiev
- Department of Plant Science, Faculty of Agriculture and Food Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
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19
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Forti G, Furia A, Bombelli P, Finazzi G. In vivo changes of the oxidation-reduction state of NADP and of the ATP/ADP cellular ratio linked to the photosynthetic activity in Chlamydomonas reinhardtii. PLANT PHYSIOLOGY 2003; 132:1464-74. [PMID: 12857827 PMCID: PMC167085 DOI: 10.1104/pp.102.018861] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2002] [Revised: 01/15/2003] [Accepted: 01/28/2003] [Indexed: 05/18/2023]
Abstract
The ATP/ADP and NADP/NADPH ratios have been measured in whole-cell extract of the green alga Chlamydomonas reinhardtii, to understand their availability for CO(2) assimilation by the Calvin cycle in vivo. Measurements were performed during the dark-light transition of both aerobic and anaerobic cells, under illumination with saturating or low light intensity. Two different patterns of behavior were observed: (a) In anaerobic cells, during the lag preceding O(2) evolution, ATP was synthesized without changes in the NADP/NADPH ratio, consistently with the operation of cyclic electron flow. (b) In aerobiosis, illumination increased the ATP/ADP ratio independently of the intensity used, whereas the amount of NADPH was decreased at limiting photon flux and regained the dark-adapted level under saturating photon flux. Moreover, under these conditions, the addition of low concentrations of uncouplers stimulated photosynthetic O(2) evolution. These observations suggest that the photosynthetic generation of reducing equivalents rather than the rate of ATP formation limits the photosynthetic assimilation of CO(2) in C. reinhardtii cells. This situation is peculiar to C. reinhardtii, because neither NADPH nor ATP limited this process in plant leaves, as shown by their increase upon illumination in barley (Hordeum vulgare) leaves, independent of light intensity. Experiments are presented and were designed to evaluate the contribution of different physiological processes that might increase the photosynthetic ATP/NADPH ratio-the Mehler reaction, respiratory ATP supply following the transfer of reducing equivalents via the malate/oxaloacetate shuttle, and cyclic electron flow around PSI-to this metabolic situation.
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Affiliation(s)
- Giorgio Forti
- Istituto di Biofisica del Consiglio Nazionale delle Ricerche, Sezione di Milano, Dipartimento di Biologia dell'Università di Milano, Via Celoria 26, Milano 20133, Italy.
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20
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Igamberdiev AU, Kleczkowski LA. Implications of adenylate kinase-governed equilibrium of adenylates on contents of free magnesium in plant cells and compartments. Biochem J 2001; 360:225-31. [PMID: 11696011 PMCID: PMC1222221 DOI: 10.1042/0264-6021:3600225] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
On the basis of the equilibrium of adenylate kinase (AK; EC 2.7.4.3), which interconverts MgATP and free AMP with MgADP and free ADP, an approach has been worked out to calculate concentrations of free magnesium (Mg(2+)), based on concentrations of total ATP, ADP and AMP in plant tissues and in individual subcellular compartments. Based on reported total adenylate contents, [Mg(2+)] in plant tissues and organelles varies significantly depending on light and dark regimes, plant age and developmental stage. In steady-state conditions, [Mg(2+)] in chloroplasts is similar in light and darkness (in the millimolar range), whereas in the cytosol it is very low in the light and increases to about 0.4 mM in darkness. During the dark-to-light transition (photosynthetic induction), the [Mg(2+)] in chloroplasts falls to low values (0.2 mM or less), corresponding to a delay in photosynthetic oxygen evolution. This delay is considered to result from lower activities of Mg-dependent enzymes in the Calvin cycle. In mitochondria, the changes in [Mg(2+)] are similar but smoother. On the other hand, when the transition from light to darkness is considered, an initial increase in [Mg(2+)] occurs in both chloroplasts and mitochondria, which may be of importance for the control of key regulatory enzymes (e.g. mitochondrial malic enzyme and pyruvate dehydrogenase complex) and for processes connected with light-enhanced dark respiration. A rationale is presented for a possible role of [MgATP]/[MgADP] ratio (rather than [ATP(total)]/[ADP(total)]) as an important component of metabolic cellular control. It is postulated that assays of total adenylates may provide an accurate measure of [Mg(2+)] in plant tissues/cells and subcellular compartments, given that the adenylates are equilibrated by AK.
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Affiliation(s)
- A U Igamberdiev
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, 901-87 Umeå, Sweden
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21
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Gardeström P. Adenylate ratios in the cytosol, chloroplasts and mitochondria of barley leaf protoplasts during photosynthesis at different carbon dioxide concentrations. FEBS Lett 2001. [DOI: 10.1016/0014-5793(87)81567-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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22
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van Voorthuysen T, Regierer B, Springer F, Dijkema C, Vreugdenhil D, Kossmann J. Introduction of polyphosphate as a novel phosphate pool in the chloroplast of transgenic potato plants modifies carbohydrate partitioning. J Biotechnol 2000; 77:65-80. [PMID: 10674215 DOI: 10.1016/s0168-1656(99)00208-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Potato plants (Solanum tuberosum L., cv. Désirée) were transformed with the polyphosphate kinase gene from Escherichia coli fused to the leader sequence of the ferredoxin oxidoreductase gene (FNR) from Spinacea oleracea under the control of the leaf specific St-LS1 promoter to introduce a novel phosphate pool in the chloroplasts of green tissues. Transgenic plants (cpPPK) in tissue culture developed necrotic lesions in older leaves and showed earlier leaf senescence while greenhouse plants showed no noticeable phenotype. Leaves of cpPPK plants contained less starch but higher concentrations of soluble sugars. The presence of polyphosphate in cpPPK leaves was demonstrated by toluidine blue staining and unambiguously verified and quantified by in vitro 31P-NMR of extracts. Polyphosphate accumulated during leaf development from 0.06 in juvenile leaves to 0.83 mg P g-1 DW in old leaves and had an average chain length of 18 residues in mature leaves. In situ 31P-NMR on small leaf pieces perfused with well-oxygenated medium showed only 0.036 mg P g-1 DW polyphosphate that was, however, greatly increased upon treatment with 50 mM ammonium sulfate at pH 7.3. This phenomenon along with a yield of 0.47 mg P g-1 DW polyphosphate from an extract of the same leaf material suggests that 93% of the polyphosphate pool is immobile. This conclusion is substantiated by the observation that no differences in polyphosphate pool sizes could be discerned between darkened and illuminated leaves, leaves treated with methylviologen or anaerobis and control leaves, treatments causing a change in the pool of ATP available for polyPi synthesis. Results are discussed in the context of the chelating properties of polyphosphates for cations and its consequences for the partitioning of photoassimilate between starch and soluble sugars.
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Affiliation(s)
- T van Voorthuysen
- Department of Plant Sciences, Wageningen University, The Netherlands
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23
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Laber B, Maurer W, Hanke C, Gräfe S, Ehlert S, Messerschmidt A, Clausen T. Characterization of recombinant Arabidopsis thaliana threonine synthase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 263:212-21. [PMID: 10429206 DOI: 10.1046/j.1432-1327.1999.00487.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Threonine synthase (TS) catalyses the last step in the biosynthesis of threonine, the pyridoxal 5'-phosphate dependent conversion of L-homoserine phosphate (HSerP) into L-threonine and inorganic phosphate. Recombinant Arabidopsis thaliana TS (aTS) was characterized to compare a higher plant TS with its counterparts from Escherichia coli and yeast. This comparison revealed several unique properties of aTS: (a) aTS is a regulatory enzyme whose activity was increased up to 85-fold by S-adenosyl-L-methionine (SAM) and specifically inhibited by AMP; (b) HSerP analogues shown previously to be potent inhibitors of E. coli TS failed to inhibit aTS; and (c) aTS was a dimer, while the E. coli and yeast enzymes are monomers. The N-terminal region of aTS is essential for its regulatory properties and protects against inhibition by HSerP analogues, as an aTS devoid of 77 N-terminal residues was neither activated by SAM nor inhibited by AMP, but was inhibited by HSerP analogues. The C-terminal region of aTS seems to be involved in dimer formation, as the N-terminally truncated aTS was also found to be a dimer. These conclusions are supported by a multiple amino-acid sequence alignment, which revealed the existence of two TS subfamilies. aTS was classified as a member of subfamily 1 and its N-terminus is at least 35 residues longer than those of any nonplant TS. Monomeric E. coli and yeast TS are members of subfamily 2, characterized by C-termini extending about 50 residues over those of subfamily 1 members. As a first step towards a better understanding of the properties of aTS, the enzyme was crystallized by the sitting drop vapour diffusion method. The crystals diffracted to beyond 0.28 nm resolution and belonged to the space group P222 (unit cell parameters: a = 6.16 nm, b = 10.54 nm, c = 14.63 nm, alpha = beta = gamma = 90 degrees).
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Affiliation(s)
- B Laber
- Hoechst Schering AgrEvo GmbH, Biochemical Research, Frankfurt am Main, Germany.
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24
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Schleucher J, Vanderveer PJ, Sharkey TD. Export of carbon from chloroplasts at night. PLANT PHYSIOLOGY 1998; 118:1439-45. [PMID: 9847119 PMCID: PMC34761 DOI: 10.1104/pp.118.4.1439] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/1998] [Accepted: 09/04/1998] [Indexed: 05/17/2023]
Abstract
Hexose export from chloroplasts at night has been inferred in previous studies of mutant and transgenic plants. We have tested whether hexose export is the normal route of carbon export from chloroplasts at night. We used nuclear magnetic resonance to distinguish glucose (Glc) made from hexose export and Glc made from triose export. Glc synthesized in vitro from fructose-6-phosphate in the presence of deuterium-labeled water had deuterium incorporated at C-2, whereas synthesis from triose phosphates caused C-2 through C-5 to become deuterated. In both tomato (Lycopersicon esculentum L. ) and bean (Phaseolus vulgaris L.), Glc from sucrose made at night in the presence of deuterium-enriched water was deuterated only in the C-2 position, indicating that >75% of carbon is exported as hexoses at night. In darkness the phosphate in the cytosol was 28 mM, whereas that in the chloroplasts was 5 mM, but hexose phosphates were 10-fold higher in the cytosol than in the chloroplasts. Therefore, hexose phosphates would not move out of chloroplasts without the input of energy. We conclude that most carbon leaves chloroplasts at night as Glc, maltose, or higher maltodextrins under normal conditions.
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25
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Pettersson G. Control properties of the Calvin photosynthesis cycle at physiological carbon dioxide concentrations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1997. [DOI: 10.1016/s0005-2728(97)00080-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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26
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Krömer S, Gardeström P, Samuelsson G. Regulation of the supply of oxaloacetate for mitochondrial metabolism via phosphoenolpyruvate carboxylase in barley leaf protoplasts. II. Effects of metabolites on PEPC activity at different activation states of the protein. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1289:351-61. [PMID: 8620019 DOI: 10.1016/0304-4165(95)00165-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The regulation of the supply of oxaloacetate (OAA) for mitochondrial metabolism via phosphoenolpyruvate carboxylase (PEPC) by metabolites is studied in barley (Hordeum vulgare L.) leaf protoplasts in light or darkness as well as under photorespiratory or non-photorespiratory conditions. Measurements on PEPC activity were performed on samples quickly frozen in liquid nitrogen to break the cell and stop metabolism and thus preserve the in vivo activation state. Glycine, serine, pyruvate, acetyl-CoA, glycolate, fructose 1,6-bisphosphate, fructose 2,6-bisphosphate and ADP had no significant effect on PEPC activity. Malate, aspartate and glutamate were strong inhibitors of PEPC activity decreasing the activity more in light versus darkness. However, at the physiological cytosolic concentration of these metabolites under the respective conditions, inhibition of PEPC activity was about the same with the exception of aspartate which inhibits more under non-photorespiratory than under photorespiratory conditions. 2-Oxoglutarate and glyoxylate decreased PEPC activity by 20 to 40% in the range of its physiological cytosolic concentration. Inhibition by physiological cytosolic concentrations of glutamine was limited. Glucose 6-phosphate, fructose 6-phosphate, 3-phosphoglycerate, dihydroxyacetonphosphate and P(i) stimulated PEPC activity significantly in their physiological cytosolic concentration range. Physiological cytosolic concentrations of glucose 6-phosphate and fructose 6-phosphate activated PEPC activity to about the same extent under all conditions applied, while 3-phosphoglycerate and dihydroxyacetonphosphate stimulating stronger under non-photorespiratory versus photorespiratory conditions. Moreover, dihydroxyacetonphosphate stimulated PEPC activity more in light versus darkness under non-photorespiratory conditions. P(i) activation of PEPC activity decreases in light versus darkness under non-photorespiratory conditions. Stimulation of PEPC activity by citrate in its physiological concentration range is limited. Glucose 1-phosphate and AMP activated PEPC activity only at concentrations higher than their physiological levels in the cytosol. Determinations of PEPC activity in the presence of different malate/glucose 6-phosphate ratios revealed that glucose 6-phosphate totally relieved the inhibitory effect of malate. The regulatory properties of PEPC activity will be discussed in relation to its functions in C3 plants.
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Affiliation(s)
- S Krömer
- Department of Plant Physiology, University of Umeå, Sweden.
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27
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Spalding EP. An apparatus for studying rapid electrophysiological responses to light demonstrated on Arabidopsis leaves. Photochem Photobiol 1995; 62:934-9. [PMID: 8570735 DOI: 10.1111/j.1751-1097.1995.tb09159.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
An apparatus for making high-resolution measurements of electrophysiological changes induced by light in plant cells was constructed. Its main components were a xenon arc lamp, an electronic shutter, a liquid light-guide, a computer equipped with an analog-to-digital converter and a computer program that controlled the shutter and data acquisition. The apparatus was used to examine transient changes in membrane potential (Vm) that occur upon illumination in Arabidopsis leaves. Light-on induced a transient hyperpolarization of 4 mV after a lag time of 0.53 s. It was followed by a much larger transient depolarization that peaked 31 s after light-on. The Vm returned to near its original value after approximately 3 min. The early changes in Vm have been proposed to result from effects of photosynthetically produced ATP on the activities of H(+)-ATPases and K+ channels at the plasma membrane. The kinetics of the initial hyperpolarization were found to be reasonably consistent with such a mechanism. It is expected that the apparatus described here will be useful in future investigations of this and other electrophysiological responses to light.
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Affiliation(s)
- E P Spalding
- Department of Botany, University of Wisconsin, Madison 53706, USA
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Moore BD, Sharkey TD, Seemann JR. Intracellular localization of CA1P and CA1P phosphatase activity in leaves of Phaseolus vulgaris L. PHOTOSYNTHESIS RESEARCH 1995; 45:219-224. [PMID: 24301533 DOI: 10.1007/bf00015562] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/1995] [Accepted: 08/07/1995] [Indexed: 06/02/2023]
Abstract
CA1P and CA1P phosphatase occur in the chloroplasts of leaf mesophyll cells of many species. However, whether either may occur exclusively in the chloroplast has not yet been established. To examine their intracellular distribution, mature, dark-or light-treated leaves of Phaseolus vulgaris were frozen, lyophilized and then centrifuged in density gradients of heptane and tetrachloroethylene. After gradient fractionation, both CA1P and CA1P phosphatase activity co-segregated with chloroplast material. Distribution analyses using sub-cellular compartment markers indicated that both CA1P and CA1P phosphatase do occur exclusively in leaf chloroplasts.
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Affiliation(s)
- B D Moore
- Department of Biochemistry, University of Nevada, 89557, Reno, NV, USA
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29
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Metabolite levels in the chloroplast and extrachloroplast compartments of barley leaf protoplasts during the initial phase of photosynthetic induction. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1993. [DOI: 10.1016/0005-2728(93)90235-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Dreier W, Preusser E, Gründel M. The Regulation of the Activity of Soluble Starch Synthase in Spinach Leaves by a Calcium-Calmodulin Dependent Protein Kinase. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s0015-3796(11)80013-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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32
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Gilmore AM, Yamamoto HY. Dark induction of zeaxanthin-dependent nonphotochemical fluorescence quenching mediated by ATP. Proc Natl Acad Sci U S A 1992; 89:1899-903. [PMID: 1542689 PMCID: PMC48561 DOI: 10.1073/pnas.89.5.1899] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Zeaxanthin-dependent nonphotochemical fluorescence quenching is a light-induced activity in plants that apparently protects against the potentially damaging effects of excess light. We report a dark-induced nonphotochemical quenching in thylakoids of Lactuca sativa L. cv. Romaine mediated by ATP. This effect is due to low lumen pH from hydrolysis-dependent proton pumping and hence required an active ATPase. The induction was optimal at 0.3 mM ATP, a physiological concentration, and occurred under conditions of little or no reverse electron flow. The properties of ATP-induced quenching were in all respects examined similar to light-induced quenching, including antimycin inhibition of quenching induction but not delta pH. We conclude that zeaxanthin-dependent quenching depends directly on lumen pH and that the role of light is indirect. Although it is known that zeaxanthin and low lumen pH are insufficient for quenching to occur, the results apparently exclude the redox state of an electron-transport carrier or formation of light-induced carotenoid triplets as a further requirement. We propose that a slow pH-dependent conformational change together with zeaxanthin cause static quenching in the pigment bed; possibly antimycin inhibits this change. Furthermore, we suggest from the ability of ATP to sustain quenching in the dark for extended periods that persistent or slowly reversible zeaxanthin quenching often observed in vivo may be due to sustained delta pH from ATP hydrolysis.
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Affiliation(s)
- A M Gilmore
- University of Hawaii, Department of Plant Molecular Physiology, Honolulu 96822
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33
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Dynamics of Nucleotides in Plants Studied on a Cellular Basis. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s0074-7696(08)62027-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
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34
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Cerović ZG, Vučinić Z, Walker DA. Photosynthetic oxygen evolution and chlorophyll fluorescence in intact isolated chloroplasts on a solid support: the influence of orthophosphate. PLANTA 1991; 184:248-253. [PMID: 24194077 DOI: 10.1007/bf00197954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/27/1990] [Indexed: 06/02/2023]
Abstract
We devised recently a method to trap intact isolated chloroplasts on a solid support consisting of membrane filters made of cellulose nitrate (Cerović et al., 1987, Plant Physiol. 84, 1249-1251). The addition of alkaline phosphatase to the reaction medium enabled continuous photosynthesis by spinach (Spinacia oleracea L.) chloroplasts to be sustained by hydrolysis of newly produced and exported triose phosphates and recycling of orthophosphate. In this system, simultaneous measurements of chlorophyll fluorescence and oxygen evolution were performed and their dependence on orthophosphate concentration was investigated. Optimal photosynthesis was obtained at a much higher initial orthophosphate concentration (2-4 mM) compared to intact chloroplasts in suspension. Secondary kinetics of chlorophyll fluorescence yield were observed and were shown to depend on the initial orthophosphate concentration.
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Affiliation(s)
- Z G Cerović
- Institute of Botany and Botanical Garden, Faculty of Biology, University of Belgrade, Takovska 43, 11 000, Belgrade, Yugoslavia
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35
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Madhusudana Rao J, Raviraj Arulanantham A, Terry N. Diurnal changes in adenylates and nicotinamide nucleotides in sugar beet leaves. PHOTOSYNTHESIS RESEARCH 1990; 23:205-212. [PMID: 24421062 DOI: 10.1007/bf00035011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/1989] [Accepted: 05/11/1989] [Indexed: 06/03/2023]
Abstract
Sugar beets (Beta vulgaris L. cv. F58-554H1) were cultured hydroponically in growth chambers at 25°C, with a photon flux density of 500 μmol m(-2)s(-1). Measurements were made of net CO2 exchange, leaf adenylates (ATP, ADP and AMP), and leaf nicotinamide nucleotides (NAD(+), NADP(+), NADH, NADPH), over the diurnal period (16h light/8 h dark) and during photosynthetic induction. All the measurements were carried out on recently expanded leaves from 5-week-old plants. When the lights were switched on in the growth chamber, the rate of photosynthetic CO2 uptake, and the levels of leaf ATP and NADPH increased to a maximum in 30 min and remained there throughout the light period. The increase in ATP over the first few minutes of illumination was associated with the phosphorylation of ADP to ATP and the increase in NADPH with the reduction of NADP(+); subsequently, the increase in ATP was associated with an increase in total adenylates while the increase in NADPH was associated with an accumulation of NADP(+) and NADPH due to the light-driven phosphorylation of NAD(+) to NADP(+). On return to darkness, ATP and NADPH values decreased much more slowly, requiring 2 to 4 hours to reach minimum values. From these results we suggest that (i) the total adenylate and NADPH and NADP(+) (but not NAD(+) and NADH) pools increase following exposure to light; (ii) the increase in pool size is not accompanied by any large change in the energy or redox states of the system; and (iii) the measured ratios of ATP/ADP and NADPH/NADP(+) for intact leaves are low and constant during steady-state illumination.
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Affiliation(s)
- J Madhusudana Rao
- Department of Plant and Soil Biology, University of California, 94720, Berkeley, CA, USA
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36
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Budde RJ, Randall DD. Pea leaf mitochondrial pyruvate dehydrogenase complex is inactivated in vivo in a light-dependent manner. Proc Natl Acad Sci U S A 1990; 87:673-6. [PMID: 11607058 PMCID: PMC53327 DOI: 10.1073/pnas.87.2.673] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We examined the effect of light on the activity of the mitochondrial pyruvate dehydrogenase complex (mt-PDC) by using intact green pea (Pisum sativum) seedlings. Upon illumination there is an initial drop in mtPDC activity followed by oscillations that dampen during the initial period of photosynthesis to a steady-state level of one-fourth or less of the mtPDC activity measured in the dark. The initial light-dependent decrease in mtPDC activity is inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (an inhibitor of photosystem II of photosynthesis) and does not occur in etiolated seedlings. Therefore, the effect of light is indirect and most likely associated with photosynthesis and/or photorespiration. Conditions that would be unfavorable for photorespiration also inhibited the light-dependent decrease in mtPDC activity.
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Affiliation(s)
- R J Budde
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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37
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Pollok M, Heber U, Naik MS. Inhibition of stomatal opening in sunflower leaves by carbon monoxide, and reversal of inhibition by light. PLANTA 1989; 178:223-230. [PMID: 24212752 DOI: 10.1007/bf00393198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/1988] [Accepted: 01/02/1989] [Indexed: 06/02/2023]
Abstract
When leaves of Helianthus annuus, whose stomates had been opened in the dark in the absence of CO2, were exposed to 25% carbon monoxide (CO), stomatal conductivity for water vapor decreased from about 0.4 to 0.2 cm·s(-1). The CO effect on stomatal aperture required a CO/O2 ratio of about 25. As this ratio was decreased the stomata opened, indicating that inhibitio of cytochrome-c oxidase by CO is competitive in respect to O2. Photosynthetically active red light was unable to reverse CO-induced stomatal closure even at high irradiances, when CO2 was absent. When it was present, stomatal opening was occasionally, but not consistently observed. Carbon monoxide did not inhibit photosynthetic carbon reduction in leaves of Helianthus.In contrast to red light, very weak blue light (405 nm) increased the stomatal aperture in the presence of CO. It also increased leaf ATP/ADP ratios which had been decreased in the presence of CO. The blue-light effect was not related to photosynthesis. Neither could it be explained by photodissociation of the cytochrome a 3-CO complex which has an absorption maximum at 430 nm. The data indicate that ATP derived from mitochondrial oxidative phosphorylation provides energy for stomatal opening in sunflower leaves in the dark as well as in the light. Indirect transfer of ATP from chloroplasts to the cytosol via the triose phosphate/phosphoglycerate exchange which is mediated by the phosphate translocator of the chloroplast envelope can support stomatal opening only if metabolite concentrations are high enough for efficient shuttle transfer of ATP. Blue light causes stomatal opening in the presence of CO by stimulating ATP synthesis.
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Affiliation(s)
- M Pollok
- Institute of Botany and Pharmaceutical Biology of the University of Würzburg, D-8700, Würzburg, Germany
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38
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Laisk A, Oja V, Kiirats O, Raschke K, Heber U. The state of the photosynthetic apparatus in leaves as analyzed by rapid gas exchange and optical methods: the pH of the chloroplast stroma and activation of enzymes in vivo. PLANTA 1989; 177:350-358. [PMID: 24212428 DOI: 10.1007/bf00403593] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/1988] [Accepted: 10/03/1988] [Indexed: 06/02/2023]
Abstract
The exchange of CO2 and O2 was measured in leaves using specially constructed equipment capable of responding to rapid transients. Optical measurements provided information on cytochrome f and P 700 oxidation in the light. The following results were obtained: i) The solubilization of CO2 was used to calculate the pH of the chloroplast stroma in darkened leaves. Values ranged from pH 7.8 to pH 8.0 in different C3 plants. ii) Illumination of predarkened leaves of Helianthus annuus L. resulted in three distinct phases of O2 evolution that illustrate the complexity of light activation of the photosynthetic apparatus. A first burst of O2 is attributed to the reduction of electron carriers of the electron-transport chain. While plastoquinone was reduced, cytochrome f was oxidized. Appreciable oxidation of P 700 became possible only during the second O2 burst, which indicates the reduction of the phosphoglycerate pool. Extensive oxidation required the opening of an electron gate on the reducing side of photosystem I. The subsequent slow rise in O2 evolution towards a steady state reflects activation of the Calvin cycle and is the result of CO2 assimilation. iii) Light-dependent CO2 uptake by predarkened leaves occurred in four phases, three of them based on pH changes in the chloroplast stroma. Initial CO2 uptake was small and probably caused by protonation of reduced plastoquinone. In the second phase, which coincided with the reduction of the pool of phosphoglycerate, the initial alkalization of the chloroplast stroma was substantially increased. In the third phase, the stroma alkalization decreased, and the fourth phase was dominated by CO2 assimilation. iv) Respiratory CO2 production was partially suppressed in the light during the second phase of O2 evolution while phosphoglycerate was being reduced.
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Affiliation(s)
- A Laisk
- Astrofüüsika Ja Atmosfäärifüüsika Institut, Eesti NSV Teaduste Akadeemia, Tartu, Eesti, USSR
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Kleczkowski LA, Randall DD. Purification and characterization of D-glycerate-3-kinase from maize leaves. PLANTA 1988; 173:221-229. [PMID: 24226402 DOI: 10.1007/bf00403014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/1987] [Accepted: 08/11/1987] [Indexed: 06/02/2023]
Abstract
Glycerate kinase (GK; EC 2.7.1.31) from maize (Zea mays L.) leaves was purified by a sequence of ammonium-sulfate precipitations and chromatography on diethylaminoethyl-cellulose, hydroxyapatite, Sephadex G-75SF and dye ligand (Green A) columns. The purest preparation was almost 1300-fold enriched and had a specific activity of 68 μmol · min(-1) · (mg protein) (-1). The enzyme was a monomer of a relative molecular mass (Mr) of 44 kDa (kdalton) as determined by gel filtration, electrophoresis in dissociating conditions and by immunoblots. The enzyme was only weakly recognized by polyclonal antibodies against purified spinach GK, indicating substantial differences in molecular structure of the two proteins. Highly reducing conditions stabilized GK activity and were required for activation of crude leaf enzyme. The enzyme had a broad pH optimum of 6.8-8.5, and formed 3-phosphoglycerate and ADP as reaction products. Apparent K ms for D-glycerate and Mg-ATP were 0.11 and 0.25 mM, respectively. The enzyme was strongly affected by a number of phosphoesters, especially by 3-phosphoglycerate (K i= 0.36 mM), fructose bisphosphates and nucleoside bisphosphates. Inhibition by 3-phosphoglycerate was competitive to Mg-ATP and noncompetitive to D-glycerate. Pyruvate was found noncompetitive to D-glycerate (K is=4 mM). The ratio of stromal concentration of Mg-ATP to phosphoesters, particularly to 3-phosphoglycerate, may be of importance in the regulation of GK during C4-photosynthesis.
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Affiliation(s)
- L A Kleczkowski
- Department of Biochemistry, Univerity of Missouri, 117 Schweitzer Hall, 65211, Columbia, MO, USA
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40
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Gans P, Rebeille F. Light inhibition of mitochondrial respiration in a mutant of Chlamydomonas reinhardtii devoid of ribulose-1,5-bisphosphate carboxylase/oxygenase activity. Arch Biochem Biophys 1988; 260:109-17. [PMID: 3341736 DOI: 10.1016/0003-9861(88)90430-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The effect of light on mitochondrial respiration has been investigated in Chlamydomonas reinhardtii rcl-u-1-10-6C, a mutant devoid of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity. No CO2 uptake was observed in the light, confirming that there was no Rubisco activity, but the CO2 evolution rate was diminished by 65 to 80%. This inhibition was ascribable to a decrease in the tricarboxylic acid cycle (Krebs cycle) activity. At the same time, O2 evolution associated with stimulation of the O2 uptake appears. Darkness or addition of DCMU fully reversed the effect of light, indicating that the inhibitory process is linked to photosystem activities. Levels of pyridine nucleotides (NAD(H) and NADP(H)) and adenine nucleotides (ATP and ADP), the most probable mediators of the interaction between photosynthesis and respiration, were measured in dark and in light. During a dark to light transition the level of NADPH increased significantly whereas the NAD(H) pool remained almost fully oxidized. The level of ADP was always extremely low. These results suggest that the inhibition of Krebs cycle activity is due to a competition for cytosolic ADP between chloroplastic photophosphorylations and oxidative phosphorylations.
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Affiliation(s)
- P Gans
- Department de Biologie, C.E.N. de Cadarache, Saint-Paul-lez-Durance, France
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41
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Furbank RT, Foyer CH, Walker DA. Interactions between ribulose-1,5-bisphosphate carboxylase and stromal metabolites. II. Corroboration of the role of this enzyme as a metabolite buffer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1987. [DOI: 10.1016/0005-2728(87)90186-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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42
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Boyle FA, Keys AJ. The state of activation of ribulose-1,5-bisphosphate carboxylase in wheat leaves. PHOTOSYNTHESIS RESEARCH 1987; 11:97-108. [PMID: 24435486 DOI: 10.1007/bf00018268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/1985] [Revised: 03/07/1986] [Indexed: 06/03/2023]
Abstract
In light and in darkness, exposure of leaf segments to CO2-free atmospheres caused a marked reduction in extractable RuBP carboxylase activity. By contrast, darkness caused a relatively small decrease in carboxylase activity in extracts from leaf segments kept in air containing CO2. Recovery of carboxylase activity in leaves during illumination in air after exposure to CO2-free conditions paralleled recovery of capacity for photosynthesis; in darkness recovery of carboxylase activity in leaves was slower than in the light. Extracts from leaves exposed to CO2-free conditions recovered activity when provided with CO2 and Mg(2+); there were clearly, however, substances in the extracts that modified the activity achieved and caused anomalous decreases and increases with time after extraction. Studies of the effect of orthophosphate on the activity of purified wheat carboxylase in vitro were consistent with the view that many of the effects observed on the activity of crude leaf extracts were due to orthophosphate content.
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Affiliation(s)
- F A Boyle
- Rothamsted Experimental Station, AL5 2JQ, Harpenden, Herts, UK
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Prinsley RT, Leegood RC. Factors affecting photosynthetic induction in spinach leaves. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1986. [DOI: 10.1016/0005-2728(86)90031-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dietz KJ, Heber U. Light and CO2 limitation of photosynthesis and states of the reactions regenerating ribulose 1,5-bisphosphate or reducing 3-phosphoglycerate. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1986. [DOI: 10.1016/0005-2728(86)90215-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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46
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Kaiser WM, Schröppel-Meier G, Wirth E. Enzyme activities in an artificial stroma medium : An experimental model for studying effects of dehydration on photosynthesis. PLANTA 1986; 167:292-299. [PMID: 24241865 DOI: 10.1007/bf00391429] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/1985] [Accepted: 10/24/1985] [Indexed: 06/02/2023]
Abstract
When spinach leaf tissue was subjected to evaporative dehydration, photosynthetic capacity at very high (5%) CO2 concentration and saturating irradiance (300 W·m(-2)), decreased in parallel to the relative water content (RWC). A 50% inhibition was observed at 60-40% RWC. In order to examine whether the inhibition was caused by increased solute concentrations in chloroplasts or cytoplasm, an artificial stroma medium (ASM) was set up containing all major osmotically relevant solutes measured in isolated intact spinach chloroplasts. Subsequently, the response of enzyme activities to normal and to increased concentrations of ASM was examined. Inhibition of enzymes by a concerted increase of all solutes was well correlated to the in-vivo response of photosynthesis to dehydration (60% inhibition at double-strength ASM). Inhibitory solutes were mainly divalent inorganic anions, such as sulfate and phosphate. Inhibition of ribulose-1,5-bisphosphate carboxylase by these ions as studied in more detail. Inhibition of the enzyme by sulfate and phosphate was competitive with respect to ribulose-1,5-bisphosphate, but not with respect to CO2. The KI for sulfate was 2.1 mmol·l(-1) and for phosphate 0.57 mmol·l(-1). Sugars and amino acids at the concentrations found in spinach chloroplasts did not prevent inhibition of enzymes by anions. The results indicate that increased anion concentrations in cells and organelles are responsible for primary, quickly reversible effects of moderate dehydration on plant tissues.
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Affiliation(s)
- W M Kaiser
- Lehrstuhl Botanik I der Universität, Mittlerer Dallenbergweg 64, D-8700, Würzburg, Federal Republic of Germany
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Klaus RE, Berger MG, Fock HP. Effect of light intensity on ammonia assimilation in maize leaves. PHOTOSYNTHESIS RESEARCH 1985; 6:221-228. [PMID: 24442920 DOI: 10.1007/bf00049278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/1984] [Revised: 11/16/1984] [Indexed: 06/03/2023]
Abstract
The effect of light on the metabolism of ammonia was studied by subjecting detached maize leaves to 150 or 1350 μmol m(-2) s(-1) PAR during incubation with the leaf base in 2 mM (15)NH4Cl. After up to 60 min, leaves were extracted. Ammonia, glutamine, glycine, serine, alanine, and aspartate were separated by isothermal distillation and ion exchange chromatography. (15)N enrichments were analyzed by emission spectroscopy. The uptake of ammonium chloride did not influence CO2 assimilation (8.3 and 17.4 μmol m(-1) s(-1) at 150 and 1350 μmol m(-2) s(-1) PAR, respectively). Leaves kept at high light intensity contained more serine and less alanine than leaves from low light treatments. Within 1 h of incubation the enrichment of ammonia extracted from leaves rose to approximately 20% (15)N. In the high light regime the amino acids contained up to 15% (15)N, whereas in low light (15)N enrichments were small (up to 6%). The kinetics of (15)N incorporation indicated that NH3 was firstly assimilated into glutamine and then into glutamate. After 15 min (15)N was also found in glycine, serine and alanine. At high light intensity nearly half of the (15)N was incorporated in glycine. On the other hand, at low light intensity alanine was the predominant (15)N sink. It is concluded that light influences ammonia assimilation at the glutamine synthetase reaction.
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Affiliation(s)
- R E Klaus
- Fachbereich Biologie der Universität Kaiserslautern, Postfach 3049, D-6750, Kaiserslautern, FRG
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Kleczkowski LA, Randall DD, Zahler WL. The substrate specificity, kinetics, and mechanism of glycerate-3-kinase from spinach leaves. Arch Biochem Biophys 1985; 236:185-94. [PMID: 2981505 DOI: 10.1016/0003-9861(85)90618-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Glycerate-3-kinase (EC 2.7.1.31) from spinach leaves shows absolute specificity for D-glycerate as phosphate acceptor, yielding 3-phosphoglycerate as a product. ATP complexed with either Mg2+ or Mn2+ is the preferred phosphate donor. The enzyme has Km (D-glycerate) = 0.25 mM, Km (Mg-ATP) = 0.21 mM, Vmax = 300 mumol min-1 mg protein-1, and a turnover number = 12,000 X min-1. The equilibrium constant for the reaction is approximately 300 at pH 7.8. Pyrophosphate, 3-phosphoglycerate and ribulose 1,5-bisphosphate are the strongest inhibitors among the phosphorylated and nonphosphorylated metabolites tested; however, their regulatory role in vivo is questioned. Substrate kinetics, as well as product and analog inhibition data, are consistent with a sequential random mechanism. The distinct characteristic of the glycerate kinase-catalyzed reaction is the formation of a dead-end complex between the enzyme, D-glycerate, and 3-phosphoglycerate.
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49
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Preiss J. Starch, sucrose biosynthesis and partition of carbon in plants are regulated by orthophosphate and triose-phosphates. Trends Biochem Sci 1984. [DOI: 10.1016/0968-0004(84)90043-4] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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50
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