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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Bouvier JW, Emms DM, Kelly S. Rubisco is evolving for improved catalytic efficiency and CO 2 assimilation in plants. Proc Natl Acad Sci U S A 2024; 121:e2321050121. [PMID: 38442173 PMCID: PMC10945770 DOI: 10.1073/pnas.2321050121] [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: 11/30/2023] [Accepted: 01/25/2024] [Indexed: 03/07/2024] Open
Abstract
Rubisco is the primary entry point for carbon into the biosphere. However, rubisco is widely regarded as inefficient leading many to question whether the enzyme can adapt to become a better catalyst. Through a phylogenetic investigation of the molecular and kinetic evolution of Form I rubisco we uncover the evolutionary trajectory of rubisco kinetic evolution in angiosperms. We show that rbcL is among the 1% of slowest-evolving genes and enzymes on Earth, accumulating one nucleotide substitution every 0.9 My and one amino acid mutation every 7.2 My. Despite this, rubisco catalysis has been continually evolving toward improved CO2/O2 specificity, carboxylase turnover, and carboxylation efficiency. Consistent with this kinetic adaptation, increased rubisco evolution has led to a concomitant improvement in leaf-level CO2 assimilation. Thus, rubisco has been slowly but continually evolving toward improved catalytic efficiency and CO2 assimilation in plants.
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Affiliation(s)
- Jacques W Bouvier
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - David M Emms
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Steven Kelly
- Department of Biology, University of Oxford, Oxford OX1 3RB, United Kingdom
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3
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Clapero V, Arrivault S, Stitt M. Natural variation in metabolism of the Calvin-Benson cycle. Semin Cell Dev Biol 2024; 155:23-36. [PMID: 36959059 DOI: 10.1016/j.semcdb.2023.02.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 02/24/2023] [Accepted: 02/24/2023] [Indexed: 03/25/2023]
Abstract
The Calvin-Benson cycle (CBC) evolved over 2 billion years ago but has been subject to massive selection due to falling atmospheric carbon dioxide, rising atmospheric oxygen and changing nutrient and water availability. In addition, large groups of organisms have evolved carbon-concentrating mechanisms (CCMs) that operate upstream of the CBC. Most previous studies of CBC diversity focused on Rubisco kinetics and regulation. Quantitative metabolite profiling provides a top-down strategy to uncover inter-species diversity in CBC operation. CBC profiles were recently published for twenty species including terrestrial C3 species, terrestrial C4 species that operate a biochemical CCM, and cyanobacteria and green algae that operate different types of biophysical CCM. Distinctive profiles were found for species with different modes of photosynthesis, revealing that evolution of the various CCMs was accompanied by co-evolution of the CBC. Diversity was also found between species that share the same mode of photosynthesis, reflecting lineage-dependent diversity of the CBC. Connectivity analysis uncovers constraints due to pathway and thermodynamic topology, and reveals that cross-species diversity in the CBC is driven by changes in the balance between regulated enzymes and in the balance between the CBC and the light reactions or end-product synthesis.
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Affiliation(s)
- Vittoria Clapero
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Golm, D-14476 Potsdam, Germany
| | - Stéphanie Arrivault
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Golm, D-14476 Potsdam, Germany.
| | - Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Golm, D-14476 Potsdam, Germany
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4
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Kumar V, Wegener M, Knieper M, Kaya A, Viehhauser A, Dietz KJ. Strategies of Molecular Signal Integration for Optimized Plant Acclimation to Stress Combinations. Methods Mol Biol 2024; 2832:3-29. [PMID: 38869784 DOI: 10.1007/978-1-0716-3973-3_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Plant growth and survival in their natural environment require versatile mitigation of diverse threats. The task is especially challenging due to the largely unpredictable interaction of countless abiotic and biotic factors. To resist an unfavorable environment, plants have evolved diverse sensing, signaling, and adaptive molecular mechanisms. Recent stress studies have identified molecular elements like secondary messengers (ROS, Ca2+, etc.), hormones (ABA, JA, etc.), and signaling proteins (SnRK, MAPK, etc.). However, major gaps remain in understanding the interaction between these pathways, and in particular under conditions of stress combinations. Here, we highlight the challenge of defining "stress" in such complex natural scenarios. Therefore, defining stress hallmarks for different combinations is crucial. We discuss three examples of robust and dynamic plant acclimation systems, outlining specific plant responses to complex stress overlaps. (a) The high plasticity of root system architecture is a decisive feature in sustainable crop development in times of global climate change. (b) Similarly, broad sensory abilities and apparent control of cellular metabolism under adverse conditions through retrograde signaling make chloroplasts an ideal hub. Functional specificity of the chloroplast-associated molecular patterns (ChAMPs) under combined stresses needs further focus. (c) The molecular integration of several hormonal signaling pathways, which bring together all cellular information to initiate the adaptive changes, needs resolving.
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Affiliation(s)
- Vijay Kumar
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Melanie Wegener
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Madita Knieper
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Armağan Kaya
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Andrea Viehhauser
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Karl-Josef Dietz
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany.
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5
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Sharkey TD. The discovery of rubisco. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:510-519. [PMID: 35689795 DOI: 10.1093/jxb/erac254] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 06/09/2022] [Indexed: 06/15/2023]
Abstract
Rubisco is possibly the most important enzyme on Earth, certainly in terms of amount. This review describes the initial reports of ribulose 1,5-bisphosphate carboxylating activity. Discoveries of core concepts are described, including its quaternary structure, the requirement for post-translational modification, and its role as an oxygenase as well as a carboxylase. Finally, the requirement for numerous chaperonins for assembly of rubisco in plants is described.
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Affiliation(s)
- Thomas D Sharkey
- MSU-DOE Plant Research Laboratory, Plant Resilience Institute, and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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6
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Ishihara H, Alseekh S, Feil R, Perera P, George GM, Niedźwiecki P, Arrivault S, Zeeman SC, Fernie AR, Lunn JE, Smith AM, Stitt M. Rising rates of starch degradation during daytime and trehalose 6-phosphate optimize carbon availability. PLANT PHYSIOLOGY 2022; 189:1976-2000. [PMID: 35486376 PMCID: PMC9342969 DOI: 10.1093/plphys/kiac162] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 03/11/2022] [Indexed: 05/06/2023]
Abstract
Many plants, including Arabidopsis (Arabidopsis thaliana), accumulate starch in the light and remobilize it to support maintenance and growth at night. Starch synthesis and degradation are usually viewed as temporally separate processes. Recently, we reported that starch is also degraded in the light. Degradation rates are generally low early in the day but rise with time. Here, we show that the rate of degradation in the light depends on time relative to dawn rather than dusk. We also show that degradation in the light is inhibited by trehalose 6-phosphate, a signal for sucrose availability. The observed responses of degradation in the light can be simulated by a skeletal model in which the rate of degradation is a function of starch content divided by time remaining until dawn. The fit is improved by extension to include feedback inhibition of starch degradation by trehalose 6-phosphate. We also investigate possible functions of simultaneous starch synthesis and degradation in the light, using empirically parameterized models and experimental approaches. The idea that this cycle buffers growth against falling rates of photosynthesis at twilight is supported by data showing that rates of protein and cell wall synthesis remain high during a simulated dusk twilight. Degradation of starch in the light may also counter over-accumulation of starch in long photoperiods and stabilize signaling around dusk. We conclude that starch degradation in the light is regulated by mechanisms similar to those that operate at night and is important for stabilizing carbon availability and signaling, thus optimizing growth in natural light conditions.
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Affiliation(s)
- Hirofumi Ishihara
- Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Saleh Alseekh
- Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
- Center for Plant Systems Biology and Biotechnology, Plovdiv 4000, Bulgaria
| | - Regina Feil
- Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Pumi Perera
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Gavin M George
- Institute of Molecular Plant Biology, ETH Zürich, Zürich, Switzerland
| | - Piotr Niedźwiecki
- Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Stephanie Arrivault
- Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Samuel C Zeeman
- Institute of Molecular Plant Biology, ETH Zürich, Zürich, Switzerland
| | - Alisdair R Fernie
- Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
- Center for Plant Systems Biology and Biotechnology, Plovdiv 4000, Bulgaria
| | - John E Lunn
- Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Alison M Smith
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
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7
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Wieloch T, Augusti A, Schleucher J. Anaplerotic flux into the Calvin-Benson cycle: hydrogen isotope evidence for in vivo occurrence in C 3 metabolism. THE NEW PHYTOLOGIST 2022; 234:405-411. [PMID: 35020197 PMCID: PMC9305100 DOI: 10.1111/nph.17957] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 12/22/2021] [Indexed: 05/02/2023]
Abstract
As the central carbon uptake pathway in photosynthetic cells, the Calvin-Benson cycle is among the most important biochemical cycles for life on Earth. A carbon flux of anaplerotic origin (i.e. through the chloroplast-localized oxidative branch of the pentose phosphate pathway) into the Calvin-Benson cycle was proposed recently. Here, we measured intramolecular deuterium abundances in leaf starch of Helianthus annuus grown at varying ambient CO2 concentrations, Ca . Additionally, we modelled deuterium fractionations expected for the anaplerotic pathway and compared modelled with measured fractionations. We report deuterium fractionation signals at H1 and H2 of starch glucose. Below a Ca change point, these signals increase with decreasing Ca consistent with modelled fractionations by anaplerotic flux. Under standard conditions (Ca = 450 ppm corresponding to intercellular CO2 concentrations, Ci , of 328 ppm), we estimate negligible anaplerotic flux. At Ca = 180 ppm (Ci = 140 ppm), more than 10% of the glucose-6-phosphate entering the starch biosynthesis pathway is diverted into the anaplerotic pathway. In conclusion, we report evidence consistent with anaplerotic carbon flux into the Calvin-Benson cycle in vivo. We propose the flux may help to: maintain high levels of ribulose 1,5-bisphosphate under source-limited growth conditions to facilitate photorespiratory nitrogen assimilation required to build-up source strength; and counteract oxidative stress.
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Affiliation(s)
- Thomas Wieloch
- Department of Medical Biochemistry and BiophysicsUmeå UniversityUmeå90187Sweden
| | - Angela Augusti
- Research Institute on Terrestrial EcosystemsNational Research CouncilPorano (TR)05010Italy
| | - Jürgen Schleucher
- Department of Medical Biochemistry and BiophysicsUmeå UniversityUmeå90187Sweden
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8
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DiBiase C, Godtfredsen E, Dahl J, Shapiro A, Brown K, Martin A, Wermuth A, Heschel MS. Maternal flower color, ultraviolet protection, and germination in
Ipomopsis aggregata
(Polemoniaceae). POPUL ECOL 2022. [DOI: 10.1002/1438-390x.12111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Charlotte DiBiase
- Department of Organismal Biology and Ecology Colorado College Colorado Springs Colorado USA
| | - Elsa Godtfredsen
- Department of Organismal Biology and Ecology Colorado College Colorado Springs Colorado USA
| | - Julian Dahl
- Department of Organismal Biology and Ecology Colorado College Colorado Springs Colorado USA
| | - Alex Shapiro
- Department of Organismal Biology and Ecology Colorado College Colorado Springs Colorado USA
| | - Keirsten Brown
- Department of Organismal Biology and Ecology Colorado College Colorado Springs Colorado USA
| | - Amanda Martin
- Department of Organismal Biology and Ecology Colorado College Colorado Springs Colorado USA
| | - Anna Wermuth
- Department of Organismal Biology and Ecology Colorado College Colorado Springs Colorado USA
| | - M. Shane Heschel
- Department of Organismal Biology and Ecology Colorado College Colorado Springs Colorado USA
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9
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Sarkar S, Dey A, Kumar V, Batiha GES, El-Esawi MA, Tomczyk M, Ray P. Fungal Endophyte: An Interactive Endosymbiont With the Capability of Modulating Host Physiology in Myriad Ways. FRONTIERS IN PLANT SCIENCE 2021; 12:701800. [PMID: 34659281 PMCID: PMC8514756 DOI: 10.3389/fpls.2021.701800] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 07/28/2021] [Indexed: 05/23/2023]
Abstract
Endophytic fungi ubiquitously dwell inside the tissue-spaces of plants, mostly asymptomatically. They grow either intercellularly or intracellularly in a particular host plant to complete the whole or part of their life cycle. They have been found to be associated with almost all the plants occurring in a natural ecosystem. Due to their important role in the survival of plants (modulate photosynthesis, increase nutrient uptake, alleviate the effect of various stresses) they have been selected to co-evolve with their hosts through the course of evolution. Many years of intense research have discovered their tremendous roles in increasing the fitness of the plants in both normal and stressed conditions. There are numerous literature regarding the involvement of various endophytic fungi in enhancing plant growth, nutrient uptake, stress tolerance, etc. But, there are scant reports documenting the specific mechanisms employed by fungal endophytes to manipulate plant physiology and exert their effects. In this review, we aim to document the probable ways undertaken by endophytic fungi to alter different physiological parameters of their host plants. Our objective is to present an in-depth elucidation about the impact of fungal endophytes on plant physiology to make this evolutionarily conserved symbiotic interaction understandable from a broader perspective.
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Affiliation(s)
- Sohini Sarkar
- Department of Life Sciences, Presidency University, Kolkata, India
| | - Abhijit Dey
- Department of Life Sciences, Presidency University, Kolkata, India
| | - Vinay Kumar
- Department of Biotechnology, Modern College of Arts, Science and Commerce, Savitribai Phule Pune University, Ganeshkhind, Pune, India
| | - Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour, AlBeheira, Egypt
| | | | - Michał Tomczyk
- Departament of Pharmacognosy, Medical University of Białystok, Białystok, Poland
| | - Puja Ray
- Department of Life Sciences, Presidency University, Kolkata, India
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10
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Stitt M, Luca Borghi G, Arrivault S. Targeted metabolite profiling as a top-down approach to uncover interspecies diversity and identify key conserved operational features in the Calvin-Benson cycle. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5961-5986. [PMID: 34473300 PMCID: PMC8411860 DOI: 10.1093/jxb/erab291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/21/2021] [Indexed: 05/02/2023]
Abstract
Improving photosynthesis is a promising avenue to increase crop yield. This will be aided by better understanding of natural variance in photosynthesis. Profiling of Calvin-Benson cycle (CBC) metabolites provides a top-down strategy to uncover interspecies diversity in CBC operation. In a study of four C4 and five C3 species, principal components analysis separated C4 species from C3 species and also separated different C4 species. These separations were driven by metabolites that reflect known species differences in their biochemistry and pathways. Unexpectedly, there was also considerable diversity between the C3 species. Falling atmospheric CO2 and changing temperature, nitrogen, and water availability have driven evolution of C4 photosynthesis in multiple lineages. We propose that analogous selective pressures drove lineage-dependent evolution of the CBC in C3 species. Examples of species-dependent variation include differences in the balance between the CBC and the light reactions, and in the balance between regulated steps in the CBC. Metabolite profiles also reveal conserved features including inactivation of enzymes in low irradiance, and maintenance of CBC metabolites at relatively high levels in the absence of net CO2 fixation. These features may be important for photosynthetic efficiency in low light, fluctuating irradiance, and when stomata close due to low water availability.
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Affiliation(s)
- Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Gian Luca Borghi
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Stéphanie Arrivault
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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11
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In vitro activity of reconstituted rubisco enzyme from Gloeobacter violaceus. J Biosci 2021. [DOI: 10.1007/s12038-021-00188-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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Sipari N, Lihavainen J, Shapiguzov A, Kangasjärvi J, Keinänen M. Primary Metabolite Responses to Oxidative Stress in Early-Senescing and Paraquat Resistant Arabidopsis thaliana rcd1 (Radical-Induced Cell Death1). FRONTIERS IN PLANT SCIENCE 2020; 11:194. [PMID: 32180786 PMCID: PMC7059619 DOI: 10.3389/fpls.2020.00194] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 02/10/2020] [Indexed: 05/04/2023]
Abstract
Rcd1 (radical-induced cell death1) is an Arabidopsis thaliana mutant, which exhibits high tolerance to paraquat [methyl viologen (MV)], herbicide that interrupts photosynthetic electron transport chain causing the formation of superoxide and inhibiting NADPH production in the chloroplast. To understand the biochemical mechanisms of MV-resistance and the role of RCD1 in oxidative stress responses, we performed metabolite profiling of wild type (Col-0) and rcd1 plants in light, after MV exposure and after prolonged darkness. The function of RCD1 has been extensively studied at transcriptomic and biochemical level, but comprehensive metabolite profiling of rcd1 mutant has not been conducted until now. The mutant plants exhibited very different metabolic features from the wild type under light conditions implying enhanced glycolytic activity, altered nitrogen and nucleotide metabolism. In light conditions, superoxide production was elevated in rcd1, but no metabolic markers of oxidative stress were detected. Elevated senescence-associated metabolite marker levels in rcd1 at early developmental stage were in line with its early-senescing phenotype and possible mitochondrial dysfunction. After MV exposure, a marked decline in the levels of glycolytic and TCA cycle intermediates in Col-0 suggested severe plastidic oxidative stress and inhibition of photosynthesis and respiration, whereas in rcd1 the results indicated sustained photosynthesis and respiration and induction of energy salvaging pathways. The accumulation of oxidative stress markers in both plant lines indicated that MV-resistance in rcd1 derived from the altered regulation of cellular metabolism and not from the restricted delivery of MV into the cells or chloroplasts. Considering the evidence from metabolomic, transcriptomic and biochemical studies, we propose that RCD1 has a negative effect on reductive metabolism and rerouting of the energy production pathways. Thus, the altered, highly active reductive metabolism, energy salvaging pathways and redox transfer between cellular compartments in rcd1 could be sufficient to avoid the negative effects of MV-induced toxicity.
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Affiliation(s)
- Nina Sipari
- Viikki Metabolomics Unit, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
- *Correspondence: Nina Sipari,
| | - Jenna Lihavainen
- Viikki Metabolomics Unit, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Alexey Shapiguzov
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | - Jaakko Kangasjärvi
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Markku Keinänen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
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13
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Borghi GL, Moraes TA, Günther M, Feil R, Mengin V, Lunn JE, Stitt M, Arrivault S. Relationship between irradiance and levels of Calvin-Benson cycle and other intermediates in the model eudicot Arabidopsis and the model monocot rice. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:5809-5825. [PMID: 31353406 PMCID: PMC6812724 DOI: 10.1093/jxb/erz346] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/22/2019] [Indexed: 05/02/2023]
Abstract
Metabolite profiles provide a top-down overview of the balance between the reactions in a pathway. We compared Calvin-Benson cycle (CBC) intermediate profiles in different conditions in Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) to learn which features of CBC regulation differ and which are shared between these model eudicot and monocot C3 species. Principal component analysis revealed that CBC intermediate profiles follow different trajectories in Arabidopsis and rice as irradiance increases. The balance between subprocesses or reactions differed, with 3-phosphoglycerate reduction being favoured in Arabidopsis and ribulose 1,5-bisphosphate regeneration in rice, and sedoheptulose-1,7-bisphosphatase being favoured in Arabidopsis compared with fructose-1,6-bisphosphatase in rice. Photosynthesis rates rose in parallel with ribulose 1,5-bisphosphate levels in Arabidopsis, but not in rice. Nevertheless, some responses were shared between Arabidopsis and rice. Fructose 1,6-bisphosphate and sedoheptulose-1,7-bisphosphate were high or peaked at very low irradiance in both species. Incomplete activation of fructose-1,6-bisphosphatase and sedoheptulose-1,7-bisphosphatase may prevent wasteful futile cycles in low irradiance. End-product synthesis is inhibited and high levels of CBC intermediates are maintained in low light or in low CO2 in both species. This may improve photosynthetic efficiency in fluctuating irradiance, and facilitate rapid CBC flux to support photorespiration and energy dissipation in low CO2.
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Affiliation(s)
- Gian Luca Borghi
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | | | - Manuela Günther
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Regina Feil
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Virginie Mengin
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - John E Lunn
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Stéphanie Arrivault
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
- Correspondence:
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14
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Zhong B, He D, Chen R, Gao T, Wang Y, Chen H, Zhang Y, Wang D. Understanding photoelectrochemical kinetics in a model CO 2 fixation reaction. Phys Chem Chem Phys 2019; 21:17517-17520. [PMID: 31380550 DOI: 10.1039/c9cp03541a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Kinetic studies of photo- and photoelectro-catalysis fixation of CO2 are rare. Herein, a typical CO2 reduction addition to trans-stilbene is studied. Through Tafel analyses, the reaction rate-determining step (RDS) is identified as the first step of an anion free radical generation from the substrate, and the reaction order is 0.5.
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Affiliation(s)
- Bingju Zhong
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, Jiangsu, P. R. China.
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15
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Abstract
The availability of renewable energy technologies is increasing dramatically across the globe thanks to their growing maturity. However, large scale electrical energy storage and retrieval will almost certainly be a required in order to raise the penetration of renewable sources into the grid. No present energy storage technology has the perfect combination of high power and energy density, low financial and environmental cost, lack of site restrictions, long cycle and calendar lifespan, easy materials availability, and fast response time. Engineered electroactive microbes could address many of the limitations of current energy storage technologies by enabling rewired carbon fixation, a process that spatially separates reactions that are normally carried out together in a photosynthetic cell and replaces the least efficient with non-biological equivalents. If successful, this could allow storage of renewable electricity through electrochemical or enzymatic fixation of carbon dioxide and subsequent storage as carbon-based energy storage molecules including hydrocarbons and non-volatile polymers at high efficiency. In this article we compile performance data on biological and non-biological component choices for rewired carbon fixation systems and identify pressing research and engineering challenges.
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Vaseghi MJ, Chibani K, Telman W, Liebthal MF, Gerken M, Schnitzer H, Mueller SM, Dietz KJ. The chloroplast 2-cysteine peroxiredoxin functions as thioredoxin oxidase in redox regulation of chloroplast metabolism. eLife 2018; 7:38194. [PMID: 30311601 PMCID: PMC6221545 DOI: 10.7554/elife.38194] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 10/07/2018] [Indexed: 12/20/2022] Open
Abstract
Thiol-dependent redox regulation controls central processes in plant cells including photosynthesis. Thioredoxins reductively activate, for example, Calvin-Benson cycle enzymes. However, the mechanism of oxidative inactivation is unknown despite its importance for efficient regulation. Here, the abundant 2-cysteine peroxiredoxin (2-CysPrx), but not its site-directed variants, mediates rapid inactivation of reductively activated fructose-1,6-bisphosphatase and NADPH-dependent malate dehydrogenase (MDH) in the presence of the proper thioredoxins. Deactivation of phosphoribulokinase (PRK) and MDH was compromised in 2cysprxAB mutant plants upon light/dark transition compared to wildtype. The decisive role of 2-CysPrx in regulating photosynthesis was evident from reoxidation kinetics of ferredoxin upon darkening of intact leaves since its half time decreased 3.5-times in 2cysprxAB. The disadvantage of inefficient deactivation turned into an advantage in fluctuating light. Physiological parameters like MDH and PRK inactivation, photosynthetic kinetics and response to fluctuating light fully recovered in 2cysprxAB mutants complemented with 2-CysPrxA underlining the significance of 2-CysPrx. The results show that the 2-CysPrx serves as electron sink in the thiol network important to oxidize reductively activated proteins and represents the missing link in the reversal of thioredoxin-dependent regulation.
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Affiliation(s)
- Mohamad-Javad Vaseghi
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
| | - Kamel Chibani
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
| | - Wilena Telman
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
| | - Michael Florian Liebthal
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
| | - Melanie Gerken
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
| | - Helena Schnitzer
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
| | - Sara Mareike Mueller
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
| | - Karl-Josef Dietz
- Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Bielefeld, Germany
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Akashi H, Okamura E, Nishihama R, Kohchi T, Hirai MY. Identification and Biochemical Characterization of the Serine Biosynthetic Enzyme 3-Phosphoglycerate Dehydrogenase in Marchantia polymorpha. FRONTIERS IN PLANT SCIENCE 2018; 9:956. [PMID: 30061906 PMCID: PMC6054995 DOI: 10.3389/fpls.2018.00956] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/13/2018] [Indexed: 05/29/2023]
Abstract
L-serine is an important molecule in all living organisms, and thus its biosynthesis is considered to be regulated according to demand. 3-Phosphoglycerate dehydrogenase (PGDH), the first committed enzyme of the phosphorylated pathway of L-serine biosynthesis, is regulated by negative feedback from L-serine in bacteria. In the case of the vascular plant Arabidopsis thaliana, two PGDH isozymes out of three are inhibited by L-serine and activated by L-alanine, L-valine, L-methionine, L-homoserine, and L-homocysteine, suggesting a more complicated regulatory mechanism of L-serine biosynthesis in A. thaliana than in bacteria. However, it remains to be clarified whether the activation mechanism of PGDH by amino acids is conserved in land plants. In this study, we identified the sole isozyme of PGDH in the liverwort Marchantia polymorpha (MpPGDH) and elucidated its biochemical characteristics. MpPGDH cDNA encodes a 65.6 kDa protein that contains a putative transit peptide for chloroplast localization. MpPGDH shares 75-80% identity with A. thaliana isozymes and forms a homotetramer in vitro. Recombinant MpPGDH exhibited an optimal pH of 9.0, apparent Michaelis constants of 0.49 ± 0.04 and 0.096 ± 0.010 mM for 3-PGA and NAD+, respectively, and apparent maximum velocity of 5.65 ± 0.10 μmol⋅min-1⋅mg-1, similar to those of A. thaliana isozymes. Phosphate ions were found to stabilize MpPGDH, suggesting that phosphate ions are also a crucial factor in the regulation of serine biosynthesis via the phosphorylated pathway in Marchantia polymorpha. MpPGDH was inhibited by L-serine in a cooperative manner and was activated by L-alanine, L-valine, L-methionine, L-homoserine, and L-homocysteine to a lesser extent than it is in A. thaliana. The results suggest that an ancestral PGDH of land plants was inhibited byL-serine and slightly activated by five other amino acids.
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Affiliation(s)
- Hiromichi Akashi
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Eiji Okamura
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | | | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Masami Y. Hirai
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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Yang SY, Huang TK, Kuo HF, Chiou TJ. Role of vacuoles in phosphorus storage and remobilization. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3045-3055. [PMID: 28077447 DOI: 10.1093/jxb/erw481] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Vacuoles play a fundamental role in storage and remobilization of various nutrients, including phosphorus (P), an essential element for cell growth and development. Cells acquire P primarily in the form of inorganic orthophosphate (Pi). However, the form of P stored in vacuoles varies by organism and tissue. Algae and yeast store polyphosphates (polyPs), whereas plants store Pi and inositol phosphates (InsPs) in vegetative tissues and seeds, respectively. In this review, we summarize how vacuolar P molecules are stored and reallocated and how these processes are regulated and co-ordinated. The roles of SYG1/PHO81/XPR1 (SPX)-domain-containing membrane proteins in allocating vacuolar P are outlined. We also highlight the importance of vacuolar P in buffering the cytoplasmic Pi concentration to maintain cellular homeostasis when the external P supply fluctuates, and present additional roles for vacuolar polyP and InsP besides being a P reserve. Furthermore, we discuss the possibility of alternative pathways to recycle Pi from other P metabolites in vacuoles. Finally, future perspectives for researching this topic and its potential application in agriculture are proposed.
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Affiliation(s)
- Shu-Yi Yang
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Teng-Kuei Huang
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Hui-Fen Kuo
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Tzyy-Jen Chiou
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
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Sena L, Uversky VN. Comparison of the intrinsic disorder propensities of the RuBisCO activase enzyme from the motile and non-motile oceanic green microalgae. INTRINSICALLY DISORDERED PROTEINS 2016; 4:e1253526. [PMID: 28232899 PMCID: PMC5314929 DOI: 10.1080/21690707.2016.1253526] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 10/20/2016] [Accepted: 10/22/2016] [Indexed: 10/20/2022]
Abstract
Green oceanic microalgae are efficient converters of solar energy into the biomass via the photosynthesis process, with the first step of carbon fixation in the photosynthesis being controlled by the enzyme ribulose-1, 5-bisphosphate carboxylase/oxygenase (RuBisCO), which is a large proteinaceous machine composed of large (L, 52 kDa) and small (S, 12 kDa) subunits arranged as a L8S8 hexadecamer that catalyzes the formation of 2 phosphoglyceric acid molecules from one ribulose 1,5-bisphosphate (RuBP) molecule and one of carbon dioxide (CO2) and that is considered as the most abundant protein on Earth. The catalytic efficiency of this protein is controlled by the RuBisCO activase (RCA) that interacts with RuBisCO and promotes the CO2 entrance to the active site of RuBisCO by removing RuBP. One of the peculiar features of RCA is the presence of functional disordered tails that might play a role in RCA-RuBisCO interaction. Based on their ability to move, microalgae are grouped into 2 major class, motile and non-motile. Motile microalgae have an obvious advantage over their non-motile counterparts because of their ability to actively migrate within the water column to find the most optimal environmental conditions. We hypothesizes that the RCA could be functionally different in the non-motile and motile microalgae. To check this hypothesis, we conducted a comparative computational analysis of the RCAs from the representatives of the non-motile (Ostreococcus tauri) and motile (Tetraselmis sp. GSL018) green oceanic microalgae.
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Affiliation(s)
- Lucia Sena
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
- USF Health Byrd Alzheimer Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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Vadiveloo A, Moheimani N, Kosterink NR, Cosgrove J, Parlevliet D, Gonzalez-Garcia C, Lubián LM. Photosynthetic performance of two Nannochloropsis spp. under different filtered light spectra. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.08.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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21
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Rodriguez GE, Reed DC, Holbrook SJ. Blade life span, structural investment, and nutrient allocation in giant kelp. Oecologia 2016; 182:397-404. [PMID: 27342660 DOI: 10.1007/s00442-016-3674-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 06/11/2016] [Indexed: 10/21/2022]
Abstract
The turnover of plant biomass largely determines the amount of energy flowing through an ecosystem and understanding the processes that regulate turnover has been of interest to ecologists for decades. Leaf life span theory has proven useful in explaining patterns of leaf turnover in relation to resource availability, but the predictions of this theory have not been tested for macroalgae. We measured blade life span, size, thickness, nitrogen content, pigment content, and maximum photosynthetic rate (P max) in the giant kelp (Macrocystis pyrifera) along a strong resource (light) gradient to test whether the predictions of leaf life span theory applied to this alga. We found that shorter blade life spans and larger blade areas were associated with increased light availability. In addition, nitrogen and P max decreased with blade age, and their decrease was greater in shorter lived blades. These observations are generally consistent with patterns observed for higher plants and the prevailing theory of leaf life span. By contrast, variation observed in pigments of giant kelp was inconsistent with that predicted by leaf life span theory, as blades growing in the most heavily shaded portion of the forest had the lowest chlorophyll content. This result may reflect the dual role of macroalgal blades in carbon fixation and nutrient absorption and the ability of giant kelp to modify blade physiology to optimize the acquisition of light and nutrients. Thus, the marine environment may place demands on resource acquisition and allocation that have not been previously considered with respect to leaf life span optimization.
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Affiliation(s)
- Gabriel E Rodriguez
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Daniel C Reed
- Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.
| | - Sally J Holbrook
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
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22
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Alagesan S, Gaudana SB, Wangikar PP. Rhythmic oscillations in KaiC1 phosphorylation and ATP/ADP ratio in nitrogen-fixing cyanobacteriumCyanothecesp. ATCC 51142. BIOL RHYTHM RES 2015. [DOI: 10.1080/09291016.2015.1116737] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Dietz KJ. Efficient high light acclimation involves rapid processes at multiple mechanistic levels. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2401-14. [PMID: 25573858 DOI: 10.1093/jxb/eru505] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Like no other chemical or physical parameter, the natural light environment of plants changes with high speed and jumps of enormous intensity. To cope with this variability, photosynthetic organisms have evolved sensing and response mechanisms that allow efficient acclimation. Most signals originate from the chloroplast itself. In addition to very fast photochemical regulation, intensive molecular communication is realized within the photosynthesizing cell, optimizing the acclimation process. Current research has opened up new perspectives on plausible but mostly unexpected complexity in signalling events, crosstalk, and process adjustments. Within seconds and minutes, redox states, levels of reactive oxygen species, metabolites, and hormones change and transmit information to the cytosol, modifying metabolic activity, gene expression, translation activity, and alternative splicing events. Signalling pathways on an intermediate time scale of several minutes to a few hours pave the way for long-term acclimation. Thereby, a new steady state of the transcriptome, proteome, and metabolism is realized within rather short time periods irrespective of the previous acclimation history to shade or sun conditions. This review provides a time line of events during six hours in the 'stressful' life of a plant.
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Affiliation(s)
- Karl-Josef Dietz
- Biochemistry and Physiology of Plants, Faculty of Biology, W5-134, Bielefeld University, University Street 25, 33501 Bielefeld, Germany
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24
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Ions channels/transporters and chloroplast regulation. Cell Calcium 2014; 58:86-97. [PMID: 25454594 DOI: 10.1016/j.ceca.2014.10.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/01/2014] [Accepted: 10/04/2014] [Indexed: 12/28/2022]
Abstract
Ions play fundamental roles in all living cells and their gradients are often essential to fuel transports, to regulate enzyme activities and to transduce energy within and between cells. Their homeostasis is therefore an essential component of the cell metabolism. Ions must be imported from the extracellular matrix to their final subcellular compartments. Among them, the chloroplast is a particularly interesting example because there, ions not only modulate enzyme activities, but also mediate ATP synthesis and actively participate in the building of the photosynthetic structures by promoting membrane-membrane interaction. In this review, we first provide a comprehensive view of the different machineries involved in ion trafficking and homeostasis in the chloroplast, and then discuss peculiar functions exerted by ions in the frame of photochemical conversion of absorbed light energy.
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Mettler T, Mühlhaus T, Hemme D, Schöttler MA, Rupprecht J, Idoine A, Veyel D, Pal SK, Yaneva-Roder L, Winck FV, Sommer F, Vosloh D, Seiwert B, Erban A, Burgos A, Arvidsson S, Schönfelder S, Arnold A, Günther M, Krause U, Lohse M, Kopka J, Nikoloski Z, Mueller-Roeber B, Willmitzer L, Bock R, Schroda M, Stitt M. Systems Analysis of the Response of Photosynthesis, Metabolism, and Growth to an Increase in Irradiance in the Photosynthetic Model Organism Chlamydomonas reinhardtii. THE PLANT CELL 2014; 26:2310-2350. [PMID: 24894045 PMCID: PMC4114937 DOI: 10.1105/tpc.114.124537] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 04/17/2014] [Accepted: 05/06/2014] [Indexed: 05/18/2023]
Abstract
We investigated the systems response of metabolism and growth after an increase in irradiance in the nonsaturating range in the algal model Chlamydomonas reinhardtii. In a three-step process, photosynthesis and the levels of metabolites increased immediately, growth increased after 10 to 15 min, and transcript and protein abundance responded by 40 and 120 to 240 min, respectively. In the first phase, starch and metabolites provided a transient buffer for carbon until growth increased. This uncouples photosynthesis from growth in a fluctuating light environment. In the first and second phases, rising metabolite levels and increased polysome loading drove an increase in fluxes. Most Calvin-Benson cycle (CBC) enzymes were substrate-limited in vivo, and strikingly, many were present at higher concentrations than their substrates, explaining how rising metabolite levels stimulate CBC flux. Rubisco, fructose-1,6-biosphosphatase, and seduheptulose-1,7-bisphosphatase were close to substrate saturation in vivo, and flux was increased by posttranslational activation. In the third phase, changes in abundance of particular proteins, including increases in plastidial ATP synthase and some CBC enzymes, relieved potential bottlenecks and readjusted protein allocation between different processes. Despite reasonable overall agreement between changes in transcript and protein abundance (R2 = 0.24), many proteins, including those in photosynthesis, changed independently of transcript abundance.
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Affiliation(s)
- Tabea Mettler
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Timo Mühlhaus
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Dorothea Hemme
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | | | - Jens Rupprecht
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Adam Idoine
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Daniel Veyel
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Sunil Kumar Pal
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Liliya Yaneva-Roder
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Flavia Vischi Winck
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany
| | - Frederik Sommer
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Daniel Vosloh
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Bettina Seiwert
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Alexander Erban
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Asdrubal Burgos
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Samuel Arvidsson
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany
| | | | - Anne Arnold
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Manuela Günther
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Ursula Krause
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Marc Lohse
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Joachim Kopka
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Zoran Nikoloski
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Bernd Mueller-Roeber
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany
| | - Lothar Willmitzer
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Michael Schroda
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
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Martins SCV, Araújo WL, Tohge T, Fernie AR, DaMatta FM. In high-light-acclimated coffee plants the metabolic machinery is adjusted to avoid oxidative stress rather than to benefit from extra light enhancement in photosynthetic yield. PLoS One 2014; 9:e94862. [PMID: 24733284 PMCID: PMC3986255 DOI: 10.1371/journal.pone.0094862] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 03/20/2014] [Indexed: 12/31/2022] Open
Abstract
Coffee (Coffea arabica L.) has been traditionally considered as shade-demanding, although it performs well without shade and even out-yields shaded coffee. Here we investigated how coffee plants adjust their metabolic machinery to varying light supply and whether these adjustments are supported by a reprogramming of the primary and secondary metabolism. We demonstrate that coffee plants are able to adjust its metabolic machinery to high light conditions through marked increases in its antioxidant capacity associated with enhanced consumption of reducing equivalents. Photorespiration and alternative pathways are suggested to be key players in reductant-consumption under high light conditions. We also demonstrate that both primary and secondary metabolism undergo extensive reprogramming under high light supply, including depression of the levels of intermediates of the tricarboxylic acid cycle that were accompanied by an up-regulation of a range of amino acids, sugars and sugar alcohols, polyamines and flavonoids such as kaempferol and quercetin derivatives. When taken together, the entire dataset is consistent with these metabolic alterations being primarily associated with oxidative stress avoidance rather than representing adjustments in order to facilitate the plants from utilizing the additional light to improve their photosynthetic performance.
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Affiliation(s)
- Samuel C. V. Martins
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Wagner L. Araújo
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
- Max-Planck-Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Takayuki Tohge
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany
| | - Alisdair R. Fernie
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany
| | - Fábio M. DaMatta
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
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Vogel MO, Moore M, König K, Pecher P, Alsharafa K, Lee J, Dietz KJ. Fast retrograde signaling in response to high light involves metabolite export, MITOGEN-ACTIVATED PROTEIN KINASE6, and AP2/ERF transcription factors in Arabidopsis. THE PLANT CELL 2014; 26:1151-65. [PMID: 24668746 PMCID: PMC4001375 DOI: 10.1105/tpc.113.121061] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/31/2014] [Accepted: 02/28/2014] [Indexed: 05/18/2023]
Abstract
Regulation of the expression of nuclear genes encoding chloroplast proteins allows for metabolic adjustment in response to changing environmental conditions. This regulation is linked to retrograde signals that transmit information on the metabolic state of the chloroplast to the nucleus. Transcripts of several APETALA2/ETHYLENE RESPONSE FACTOR transcription factors (AP2/ERF-TFs) were found to respond within 10 min after transfer of low-light-acclimated Arabidopsis thaliana plants to high light. Initiation of this transcriptional response was completed within 1 min after transfer to high light. The fast responses of four AP2/ERF genes, ERF6, RRTF1, ERF104, and ERF105, were entirely deregulated in triose phosphate/phosphate translocator (tpt) mutants. Similarly, activation of MITOGEN-ACTIVATED PROTEIN KINASE6 (MPK6) was upregulated after 1 min in the wild type but not in the tpt mutant. Based on this, together with altered transcript regulation in mpk6 and erf6 mutants, a retrograde signal transmission model is proposed starting with metabolite export through the triose phosphate/phosphate translocator with subsequent MPK6 activation leading to initiation of AP2/ERF-TF gene expression and other downstream gene targets. The results show that operational retrograde signaling in response to high light involves a metabolite-linked pathway in addition to previously described redox and hormonal pathways.
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Affiliation(s)
- Marc Oliver Vogel
- Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany
| | - Marten Moore
- Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany
| | - Katharina König
- Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany
| | - Pascal Pecher
- Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Khalid Alsharafa
- Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany
| | - Justin Lee
- Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Karl-Josef Dietz
- Biochemistry and Physiology of Plants, Bielefeld University, 33501 Bielefeld, Germany
- Address correspondence to
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Heiber I, Cai W, Baier M. Linking chloroplast antioxidant defense to carbohydrate availability: the transcript abundance of stromal ascorbate peroxidase is sugar-controlled via ascorbate biosynthesis. MOLECULAR PLANT 2014; 7:58-70. [PMID: 24203232 DOI: 10.1093/mp/sst154] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
All genes encoding chloroplast antioxidant enzymes are nuclear-encoded and posttranscriptionally targeted to chloroplasts. The transcript levels of most of them decreased upon sucrose feeding like the transcript levels of many genes encoding components of the photosynthetic electron transport chain. However, the transcript abundance of stromal ascorbate peroxidase (s-APX; At4g08390) increased. Due to mild sugar application conditions, the plants kept the phosphorylation status of the ADP+ATP pool and the redox states of the NADPH+NADP+ and the ascorbate pools under control, which excludes them as signals in s-APX regulation. Correlation with ascorbate pool size regulation and comparison of transcript abundance regulation in the starch-biosynthetic mutant adg1, the ascorbate biosynthesis mutant vtc1, and the abscisic acid (ABA) biosynthetic mutant aba2 showed a link between sugar induction of s-APX and ascorbate biosynthesis.
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Affiliation(s)
- Isabelle Heiber
- a Former address: Plant Physiology and Biochemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
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Davis MC, Fiehn O, Durnford DG. Metabolic acclimation to excess light intensity in Chlamydomonas reinhardtii. PLANT, CELL & ENVIRONMENT 2013; 36:1391-405. [PMID: 23346954 DOI: 10.1111/pce.12071] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/10/2013] [Indexed: 05/08/2023]
Abstract
There are several well-described acclimation responses to excess light in green algae but the effect on metabolism has not been thoroughly investigated. This study examines the metabolic changes during photoacclimation to high-light (HL) stress in Chlamydomonas reinhardtii using nuclear magnetic resonance and mass spectrometry. Using principal component analysis, a clear metabolic response to HL intensity was observed on global metabolite pools, with major changes in the levels of amino acids and related nitrogen metabolites. Amino acid pools increased during short-term photoacclimation, but were especially prominent in HL-acclimated cultures. Unexpectedly, we observed an increase in mitochondrial metabolism through downstream photorespiratory pathways. The expression of two genes encoding key enzymes in the photorespiratory pathway, glycolate dehydrogenase and malate synthase, were highly responsive to the HL stress. We propose that this pathway contributes to metabolite pools involved in nitrogen assimilation and may play a direct role in photoacclimation. Our results suggest that primary and secondary metabolism is highly pliable and plays a critical role in coping with the energetic imbalance during HL exposure and a necessary adjustment to support an increased growth rate that is an effective energy sink for the excess reducing power generated during HL stress.
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Affiliation(s)
- Maria C Davis
- Department of Biology, University of New Brunswick, Fredericton, NB E3B 5A3, Canada
| | - Oliver Fiehn
- Genome Center, University of California Davis, Davis, CA, 95616, USA
| | - Dion G Durnford
- Department of Biology, University of New Brunswick, Fredericton, NB, Canada, E3B 5A3
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Pal SK, Liput M, Piques M, Ishihara H, Obata T, Martins MC, Sulpice R, van Dongen JT, Fernie AR, Yadav UP, Lunn JE, Usadel B, Stitt M. Diurnal changes of polysome loading track sucrose content in the rosette of wild-type arabidopsis and the starchless pgm mutant. PLANT PHYSIOLOGY 2013; 162:1246-65. [PMID: 23674104 PMCID: PMC3707535 DOI: 10.1104/pp.112.212258] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 04/26/2013] [Indexed: 05/18/2023]
Abstract
Growth is driven by newly fixed carbon in the light, but at night it depends on reserves, like starch, that are laid down in the light. Unless plants coordinate their growth with diurnal changes in the carbon supply, they will experience acute carbon starvation during the night. Protein synthesis represents a major component of cellular growth. Polysome loading was investigated during the diurnal cycle, an extended night, and low CO2 in Arabidopsis (Arabidopsis thaliana) Columbia (Col-0) and in the starchless phosphoglucomutase (pgm) mutant. In Col-0, polysome loading was 60% to 70% in the light, 40% to 45% for much of the night, and less than 20% in an extended night, while in pgm, it fell to less than 25% early in the night. Quantification of ribosomal RNA species using quantitative reverse transcription-polymerase chain reaction revealed that polysome loading remained high for much of the night in the cytosol, was strongly light dependent in the plastid, and was always high in mitochondria. The rosette sucrose content correlated with overall and with cytosolic polysome loading. Ribosome abundance did not show significant diurnal changes. However, compared with Col-0, pgm had decreased and increased abundance of plastidic and mitochondrial ribosomes, respectively. Incorporation of label from (13)CO2 into protein confirmed that protein synthesis continues at a diminished rate in the dark. Modeling revealed that a decrease in polysome loading at night is required to balance protein synthesis with the availability of carbon from starch breakdown. Costs are also reduced by using amino acids that accumulated in the previous light period. These results uncover a tight coordination of protein synthesis with the momentary supply of carbon.
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Affiliation(s)
| | | | | | - Hirofumi Ishihara
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Toshihiro Obata
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Marina C.M. Martins
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | | | - Joost T. van Dongen
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Alisdair R. Fernie
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | | | - John E. Lunn
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | | | - Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
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Carmo-Silva AE, Salvucci ME. The regulatory properties of Rubisco activase differ among species and affect photosynthetic induction during light transitions. PLANT PHYSIOLOGY 2013; 161:1645-55. [PMID: 23417088 PMCID: PMC3613445 DOI: 10.1104/pp.112.213348] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Accepted: 02/14/2013] [Indexed: 05/04/2023]
Abstract
Rubisco's catalytic chaperone, Rubisco activase (Rca), uses the energy from ATP hydrolysis to restore catalytic competence to Rubisco. In Arabidopsis (Arabidopsis thaliana), inhibition of Rca activity by ADP is fine tuned by redox regulation of the α-isoform. To elucidate the mechanism for Rca regulation in species containing only the redox-insensitive β-isoform, the response of activity to ADP was characterized for different Rca forms. When assayed in leaf extracts, Rubisco activation was significantly inhibited by physiological ratios of ADP to ATP in species containing both α-Rca and β-Rca (Arabidopsis and camelina [Camelina sativa]) or just the β-Rca (tobacco [Nicotiana tabacum]). However, Rca activity was insensitive to ADP inhibition in an Arabidopsis transformant, rwt43, which expresses only Arabidopsis β-Rca, although not in a transformant of Arabidopsis that expresses a tobacco-like β-Rca. ATP hydrolysis by recombinant Arabidopsis β-Rca was much less sensitive to inhibition by ADP than recombinant tobacco β-Rca. Mutation of 17 amino acids in the tobacco β-Rca to the corresponding Arabidopsis residues reduced ADP sensitivity. In planta, Rubisco deactivated at low irradiance except in the Arabidopsis rwt43 transformant containing an ADP-insensitive Rca. Induction of CO2 assimilation after transition from low to high irradiance was much more rapid in the rwt43 transformant compared with plants containing ADP-sensitive Rca forms. The faster rate of photosynthetic induction and a greater enhancement of growth under a fluctuating light regime by the rwt43 transformant compared with wild-type Arabidopsis suggests that manipulation of Rca regulation might provide a strategy for enhancing photosynthetic performance in certain variable light environments.
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Affiliation(s)
| | - Michael E. Salvucci
- United States Department of Agriculture, Agricultural Research Service, Arid-Land Agricultural Research Center, Maricopa, Arizona 85138
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Hofmann LC, Straub S, Bischof K. Elevated CO2 levels affect the activity of nitrate reductase and carbonic anhydrase in the calcifying rhodophyte Corallina officinalis. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:899-908. [PMID: 23314813 PMCID: PMC3580807 DOI: 10.1093/jxb/ers369] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The concentration of CO(2) in global surface ocean waters is increasing due to rising atmospheric CO(2) emissions, resulting in lower pH and a lower saturation state of carbonate ions. Such changes in seawater chemistry are expected to impact calcification in calcifying marine organisms. However, other physiological processes related to calcification might also be affected, including enzyme activity. In a mesocosm experiment, macroalgal communities were exposed to three CO(2) concentrations (380, 665, and 1486 µatm) to determine how the activity of two enzymes related to inorganic carbon uptake and nutrient assimilation in Corallina officinalis, an abundant calcifying rhodophyte, will be affected by elevated CO(2) concentrations. The activity of external carbonic anhydrase, an important enzyme functioning in macroalgal carbon-concentrating mechanisms, was inversely related to CO(2) concentration after long-term exposure (12 weeks). Nitrate reductase, the enzyme responsible for reduction of nitrate to nitrite, was stimulated by CO(2) and was highest in algae grown at 665 µatm CO(2). Nitrate and phosphate uptake rates were inversely related to CO(2), while ammonium uptake was unaffected, and the percentage of inorganic carbon in the algal skeleton decreased with increasing CO(2). The results indicate that the processes of inorganic carbon and nutrient uptake and assimilation are affected by elevated CO(2) due to changes in enzyme activity, which change the energy balance and physiological status of C. officinalis, therefore affecting its competitive interactions with other macroalgae. The ecological implications of the physiological changes in C. officinalis in response to elevated CO(2) are discussed.
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Affiliation(s)
- Laurie C Hofmann
- Marine Botany, Bremen Marine Ecology Centre for Research and Education, University of Bremen, Leobener Str. NW2, Bremen, Germany.
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Liu R, Yuan G, Joe CL, Lightburn TE, Tan KL, Wang D. Silicon nanowires as photoelectrodes for carbon dioxide fixation. Angew Chem Int Ed Engl 2012; 51:6709-12. [PMID: 22615263 PMCID: PMC3480189 DOI: 10.1002/anie.201202569] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Indexed: 01/06/2023]
Affiliation(s)
| | | | - Candice L. Joe
- Merkert Chemistry Center, Department of Chemistry, Boston College, 2609 Beacon St. Chestnut Hill, MA, USA 02467
| | - Thomas E. Lightburn
- Merkert Chemistry Center, Department of Chemistry, Boston College, 2609 Beacon St. Chestnut Hill, MA, USA 02467
| | - Kian L. Tan
- Merkert Chemistry Center, Department of Chemistry, Boston College, 2609 Beacon St. Chestnut Hill, MA, USA 02467
| | - Dunwei Wang
- Merkert Chemistry Center, Department of Chemistry, Boston College, 2609 Beacon St. Chestnut Hill, MA, USA 02467
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Liu R, Yuan G, Joe CL, Lightburn TE, Tan KL, Wang D. Silicon Nanowires as Photoelectrodes for Carbon Dioxide Fixation. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202569] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Thermodynamic constraints shape the structure of carbon fixation pathways. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1646-59. [PMID: 22609686 DOI: 10.1016/j.bbabio.2012.05.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/07/2012] [Accepted: 05/09/2012] [Indexed: 11/27/2022]
Abstract
Thermodynamics impose a major constraint on the structure of metabolic pathways. Here, we use carbon fixation pathways to demonstrate how thermodynamics shape the structure of pathways and determine the cellular resources they consume. We analyze the energetic profile of prototypical reactions and show that each reaction type displays a characteristic change in Gibbs energy. Specifically, although carbon fixation pathways display a considerable structural variability, they are all energetically constrained by two types of reactions: carboxylation and carboxyl reduction. In fact, all adenosine triphosphate (ATP) molecules consumed by carbon fixation pathways - with a single exception - are used, directly or indirectly, to power one of these unfavorable reactions. When an indirect coupling is employed, the energy released by ATP hydrolysis is used to establish another chemical bond with high energy of hydrolysis, e.g. a thioester. This bond is cleaved by a downstream enzyme to energize an unfavorable reaction. Notably, many pathways exhibit reduced ATP requirement as they couple unfavorable carboxylation or carboxyl reduction reactions to exergonic reactions other than ATP hydrolysis. In the most extreme example, the reductive acetyl coenzyme A (acetyl-CoA) pathway bypasses almost all ATP-consuming reactions. On the other hand, the reductive pentose phosphate pathway appears to be the least ATP-efficient because it is the only carbon fixation pathway that invests ATP in metabolic aims other than carboxylation and carboxyl reduction. Altogether, our analysis indicates that basic thermodynamic considerations accurately predict the resource investment required to support a metabolic pathway and further identifies biochemical mechanisms that can decrease this requirement.
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Combinatorial signal integration by APETALA2/Ethylene Response Factor (ERF)-transcription factors and the involvement of AP2-2 in starvation response. Int J Mol Sci 2012; 13:5933-5951. [PMID: 22754341 PMCID: PMC3382747 DOI: 10.3390/ijms13055933] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 04/21/2012] [Accepted: 05/08/2012] [Indexed: 12/24/2022] Open
Abstract
Transcription factors of the APETALA 2/Ethylene Response Factor (AP2/ERF)- family have been implicated in diverse processes during development, stress acclimation and retrograde signaling. Fifty-three leaf-expressed AP2/ERFs were screened for their transcriptional response to abscisic acid (ABA), 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), methylviologen (MV), sucrose and high or low light, respectively, and revealed high reactivity to these effectors. Six of them (AP2-2, ARF14, CEJ1, ERF8, ERF11, RAP2.5) were selected for combinatorial response analysis to ABA, DCMU and high light. Additive, synergistic and antagonistic effects demonstrated that these transcription factors are components of multiple signaling pathways. AP2-2 (At1g79700) was subjected to an in depth study. AP2-2 transcripts were high under conditions linked to limited carbohydrate availability and stress and down-regulated in extended light phase, high light or in the presence of sugar. ap2-2 knock out plants had unchanged metabolite profiles and transcript levels of co-expressed genes in extended darkness. However, ap2-2 revealed more efficient germination and faster early growth under high sugar, osmotic or salinity stress, but the difference was abolished in the absence of sugar or during subsequent growth. It is suggested that AP2-2 is involved in mediating starvation-related and hormonal signals.
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Marcus Y, Altman-Gueta H, Wolff Y, Gurevitz M. Rubisco mutagenesis provides new insight into limitations on photosynthesis and growth in Synechocystis PCC6803. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:4173-82. [PMID: 21551078 PMCID: PMC3153676 DOI: 10.1093/jxb/err116] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Orthophosphate (Pi) stimulates the activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) while paradoxically inhibiting its catalysis. Of three Pi-binding sites, the roles of the 5P- and latch sites have been documented, whereas that of the 1P-site remained unclear. Conserved residues at the 1P-site of Rubisco from the cyanobacterium Synechocystis PCC6803 were substituted and the kinetic properties of the enzyme derivatives and effects on cell photosynthesis and growth were examined. While Pi-stimulated Rubisco activation diminished for enzyme mutants T65A/S and G404A, inhibition of catalysis by Pi remained unchanged. Together with previous studies, the results suggest that all three Pi-binding sites are involved in stimulation of Rubisco activation, whereas only the 5P-site is involved in inhibition of catalysis. While all the mutations reduced the catalytic turnover of Rubisco (K(cat)) between 6- and 20-fold, the photosynthesis and growth rates under saturating irradiance and inorganic carbon (Ci) concentrations were only reduced 40-50% (in the T65A/S mutants) or not at all (G404A mutant). Analysis of the mutant cells revealed a 3-fold increase in Rubisco content that partially compensated for the reduced K(cat) so that the carboxylation rate per chlorophyll was one-third of that in the wild type. Correlation between the kinetic properties of Rubisco and the photosynthetic rate (P(max)) under saturating irradiance and Ci concentrations indicate that a >60% reduction in K(cat) can be tolerated before P(max) in Synechocystsis PCC6803 is affected. These results indicate that the limitation of Rubisco activity on the rate of photosynthesis in Synechocystis is low. Determination of Calvin cycle metabolites revealed that unlike in higher plants, cyanobacterial photosynthesis is constrained by phosphoglycerate reduction probably due to limitation of ATP or NADPH.
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Affiliation(s)
- Yehouda Marcus
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
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Shi Y, Lou K, Li C. Growth and photosynthetic efficiency promotion of sugar beet (Beta vulgaris L.) by endophytic bacteria. PHOTOSYNTHESIS RESEARCH 2010; 105:5-13. [PMID: 20405213 DOI: 10.1007/s11120-010-9547-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Accepted: 03/26/2010] [Indexed: 05/18/2023]
Abstract
Very little is known about the physiological interactions between plants and endophytic bacteria. We investigated the impact of three endophytic bacteria, Bacillus pumilus 2-1, Chryseobacterium indologene 2-2, and Acinetobacter johnsonii 3-1, on the photosynthetic capacity and growth of sugar beet. Endophyte-free plants were obtained first and infected with the bacteria. Measurements of total chlorophyll content revealed very significant differences between endophyte-free beet plants and some infected by endophytic bacteria. The maximum photochemical yield (Fv/Fm) was used to determine any photosynthetic effect on plants caused by biotic or abiotic factors. After 30 days of growth, there was significantly higher Fv/Fm for endophyte-infected than endophyte-free plants. The light response curves of beet showed that photosynthetic capacity was significantly increased in endophyte-infected plants. Photosynthesis of endophyte-free plants was saturated at 1,300 micromol m(-2) s(-1), whereas endophyte-infected plants were not saturated at the irradiance used. The effect seemed to be due to promotion of electron transport in the thylakoid membranes. Promotion of photosynthetic capacity in sugar beet was due to increased chlorophyll content, leading to a consequent increased carbohydrate synthesis. It is possible that the increased maximum yield of photosynthesis in sugar beet was promoted by phytohormones and produced by the bacteria.
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Affiliation(s)
- Yingwu Shi
- Institute of Microbiology, Xinjiang Academy of Agriculture Science, Urumqi, Xinjiang, China.
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Tsuyama M, Kobayashi Y. Reduction of the primary donor P700 of photosystem I during steady-state photosynthesis under low light in Arabidopsis. PHOTOSYNTHESIS RESEARCH 2009; 99:37-47. [PMID: 18975133 DOI: 10.1007/s11120-008-9379-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 10/06/2008] [Indexed: 05/27/2023]
Abstract
During steady-state photosynthesis in low-light, 830-nm absorption (A(830)) by leaves was close to that in darkness in Arabidopsis, indicating that the primary donor P700 in the reaction center of photosystem I (PSI) was in reduced form. However, P700 was not fully oxidized by a saturating light pulse, suggesting the presence of a population of PSI centers with reduced P700 that remains thermodynamically stable during the application of the saturating light pulse (i.e., reduced-inactive P700). To substantiate this, the effects of methyl viologen (MV) and far-red light on P700 oxidation by the saturating light pulse were analyzed, and the cumulative effects of repetitive application of the saturating light pulse on photosynthesis were analyzed using a mutant crr2-2 with impaired PSI cyclic electron flow. We concluded that the reduced-inactive P700 in low-light as revealed by saturating light pulse indicates limitations of electron flow at the PSI acceptor side.
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Affiliation(s)
- Michito Tsuyama
- Department of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
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The Role of Peroxiredoxins in Oxygenic Photosynthesis of Cyanobacteria and Higher Plants: Peroxide Detoxification or Redox Sensing? PHOTOPROTECTION, PHOTOINHIBITION, GENE REGULATION, AND ENVIRONMENT 2008. [DOI: 10.1007/1-4020-3579-9_19] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Guo B, Jin Y, Wussler C, Blancaflor EB, Motes CM, Versaw WK. Functional analysis of the Arabidopsis PHT4 family of intracellular phosphate transporters. THE NEW PHYTOLOGIST 2008; 177:889-898. [PMID: 18086223 DOI: 10.1111/j.1469-8137.2007.02331.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The transport of phosphate (Pi) between subcellular compartments is central to metabolic regulation. Although some of the transporters involved in controlling the intracellular distribution of Pi have been identified in plants, others are predicted from genetic, biochemical and bioinformatics studies. Heterologous expression in yeast, and gene expression and localization in plants were used to characterize all six members of an Arabidopsis thaliana membrane transporter family designated here as PHT4. PHT4 proteins share similarity with SLC17/type I Pi transporters, a diverse group of animal proteins involved in the transport of Pi, organic anions and chloride. All of the PHT4 proteins mediate Pi transport in yeast with high specificity. Bioinformatic analysis and localization of PHT4-GFP fusion proteins indicate that five of the proteins are targeted to the plastid envelope, and the sixth resides in the Golgi apparatus. PHT4 genes are expressed in both roots and leaves, although two of the genes are expressed predominantly in leaves and one mostly in roots. These expression patterns, together with Pi transport activities and subcellular locations, suggest roles for PHT4 proteins in the transport of Pi between the cytosol and chloroplasts, heterotrophic plastids and the Golgi apparatus.
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Affiliation(s)
| | | | | | - E B Blancaflor
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - C M Motes
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - W K Versaw
- Department of Biology
- Molecular and Environmental Plant Sciences Program, Texas A&M University, College Station, TX 77843, USA
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Zhu XG, de Sturler E, Long SP. Optimizing the distribution of resources between enzymes of carbon metabolism can dramatically increase photosynthetic rate: a numerical simulation using an evolutionary algorithm. PLANT PHYSIOLOGY 2007; 145:513-26. [PMID: 17720759 PMCID: PMC2048738 DOI: 10.1104/pp.107.103713] [Citation(s) in RCA: 245] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 07/22/2007] [Indexed: 05/16/2023]
Abstract
The distribution of resources between enzymes of photosynthetic carbon metabolism might be assumed to have been optimized by natural selection. However, natural selection for survival and fecundity does not necessarily select for maximal photosynthetic productivity. Further, the concentration of a key substrate, atmospheric CO(2), has changed more over the past 100 years than the past 25 million years, with the likelihood that natural selection has had inadequate time to reoptimize resource partitioning for this change. Could photosynthetic rate be increased by altered partitioning of resources among the enzymes of carbon metabolism? This question is addressed using an "evolutionary" algorithm to progressively search for multiple alterations in partitioning that increase photosynthetic rate. To do this, we extended existing metabolic models of C(3) photosynthesis by including the photorespiratory pathway (PCOP) and metabolism to starch and sucrose to develop a complete dynamic model of photosynthetic carbon metabolism. The model consists of linked differential equations, each representing the change of concentration of one metabolite. Initial concentrations of metabolites and maximal activities of enzymes were extracted from the literature. The dynamics of CO(2) fixation and metabolite concentrations were realistically simulated by numerical integration, such that the model could mimic well-established physiological phenomena. For example, a realistic steady-state rate of CO(2) uptake was attained and then reattained after perturbing O(2) concentration. Using an evolutionary algorithm, partitioning of a fixed total amount of protein-nitrogen between enzymes was allowed to vary. The individual with the higher light-saturated photosynthetic rate was selected and used to seed the next generation. After 1,500 generations, photosynthesis was increased substantially. This suggests that the "typical" partitioning in C(3) leaves might be suboptimal for maximizing the light-saturated rate of photosynthesis. An overinvestment in PCOP enzymes and underinvestment in Rubisco, sedoheptulose-1,7-bisphosphatase, and fructose-1,6-bisphosphate aldolase were indicated. Increase in sink capacity, such as increase in ADP-glucose pyrophosphorylase, was also indicated to lead to increased CO(2) uptake rate. These results suggest that manipulation of partitioning could greatly increase carbon gain without any increase in the total protein-nitrogen investment in the apparatus for photosynthetic carbon metabolism.
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Affiliation(s)
- Xin-Guang Zhu
- Department of Plant Biology and Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Baker NR, Harbinson J, Kramer DM. Determining the limitations and regulation of photosynthetic energy transduction in leaves. PLANT, CELL & ENVIRONMENT 2007; 30:1107-25. [PMID: 17661750 DOI: 10.1111/j.1365-3040.2007.01680.x] [Citation(s) in RCA: 243] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The light-dependent production of ATP and reductants by the photosynthetic apparatus in vivo involves a series of electron and proton transfers. Consideration is given as to how electron fluxes through photosystem I (PSI), using absorption spectroscopy, and through photosystem II (PSII), using chlorophyll fluorescence analyses, can be estimated in vivo. Measurements of light-induced electrochromic shifts using absorption spectroscopy provide a means of analyzing the proton fluxes across the thylakoid membranes in vivo. Regulation of these electron and proton fluxes is required for the thylakoids to meet the fluctuating metabolic demands of the cell. Chloroplasts exhibit a wide and flexible range of mechanisms to regulate electron and proton fluxes that enable chloroplasts to match light use for ATP and reductant production with the prevailing metabolic requirements. Non-invasive probing of electron fluxes through PSI and PSII, and proton fluxes across the thylakoid membranes can provide insights into the operation of such regulatory processes in vivo.
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Affiliation(s)
- Neil R Baker
- Department of Biological Sciences, University of Essex, Colchester, CO4 3SQ, Essex, UK.
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Hohmann-Marriott MF, Blankenship RE. Variable fluorescence in green sulfur bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:106-13. [PMID: 17189610 DOI: 10.1016/j.bbabio.2006.11.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 11/01/2006] [Accepted: 11/07/2006] [Indexed: 11/22/2022]
Abstract
Green sulfur bacteria possess a complex photosynthetic machinery. The dominant light harvesting systems are chlorosomes, which consist of bacteriochlorophyll c, d or e oligomers with small amounts of protein. The chlorosomes are energetically coupled to the membrane-embedded iron sulfur-type reaction center via a bacteriochlorophyll a-containing baseplate protein and the Fenna-Matthews-Olson (FMO) antenna protein. The fluorescence yield and spectral properties of these photosynthetic complexes were investigated in intact cells of several species of green sulfur bacteria under physiological, anaerobic conditions. Surprisingly, green sulfur bacteria show a complex modulation of fluorescence yield upon illumination that is very similar to that observed in oxygenic phototrophs. Within a few seconds of illumination, the fluorescence reaches a maximum, which decreases within a minute of illumination to a lower steady state. Fluorescence spectroscopy reveals that the fluorescence yield during both processes is primarily modulated on the FMO-protein level, while the emission from chlorosomes remains mostly unchanged. The two most likely candidates that modulate bacteriochlorophyll fluorescence are (1) direct excitation quenching at the FMO-protein level and (2) indirect modulation of FMO-protein fluorescence by the reduction state of electron carriers that are part of the reaction center.
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Wormuth D, Baier M, Kandlbinder A, Scheibe R, Hartung W, Dietz KJ. Regulation of gene expression by photosynthetic signals triggered through modified CO2 availability. BMC PLANT BIOLOGY 2006; 6:15. [PMID: 16916444 PMCID: PMC1579212 DOI: 10.1186/1471-2229-6-15] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Accepted: 08/17/2006] [Indexed: 05/11/2023]
Abstract
BACKGROUND To coordinate metabolite fluxes and energy availability, plants adjust metabolism and gene expression to environmental changes through employment of interacting signalling pathways. RESULTS Comparing the response of Arabidopsis wild-type plants with that of the mutants adg1, pgr1 and vtc1 upon altered CO2-availability, the regulatory role of the cellular energy status, photosynthetic electron transport, the redox state and concentration of ascorbate and glutathione and the assimilatory force was analyzed in relation to the transcript abundance of stress-responsive nuclear encoded genes and psaA and psbA encoding the reaction centre proteins of photosystem I and II, respectively. Transcript abundance of Bap1, Stp1, psaA and psaB was coupled with seven metabolic parameters. Especially for psaA and psaB, the complex analysis demonstrated that the assumed PQ-dependent redox control is subordinate to signals linked to the relative availability of 3-PGA and DHAP, which define the assimilatory force. For the transcripts of sAPx and Csd2 high correlations with the calculated redox state of NADPH were observed in pgr1, but not in wild-type, suggesting that in wild-type plants signals depending on thylakoid acidification overlay a predominant redox-signal. Strongest correlation with the redox state of ascorbate was observed for 2CPA, whose transcript abundance regulation however was almost insensitive to the ascorbate content demonstrating dominance of redox regulation over metabolite sensing. CONCLUSION In the mutants, signalling pathways are partially uncoupled, demonstrating dominance of metabolic control of photoreaction centre expression over sensing the redox state of the PQ-pool. The balance between the cellular redox poise and the energy signature regulates sAPx and Csd2 transcript abundance, while 2CPA expression is primarily redox-controlled.
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Affiliation(s)
- Dennis Wormuth
- Biochemistry and Physiology of Plants, Bielefeld University – W5, 33501 Bielefeld, Germany
| | - Margarete Baier
- Biochemistry and Physiology of Plants, Bielefeld University – W5, 33501 Bielefeld, Germany
| | - Andrea Kandlbinder
- Biochemistry and Physiology of Plants, Bielefeld University – W5, 33501 Bielefeld, Germany
| | - Renate Scheibe
- Plant Physiology, University of Osnabrück, FB 5, 49069 Osnabrück, Germany
| | - Wolfram Hartung
- Molecular Plant Physiology and Biophysics, Julius von Sachs-Institut für Biowissenschaften, 97082 Würzburg, Germany
| | - Karl-Josef Dietz
- Biochemistry and Physiology of Plants, Bielefeld University – W5, 33501 Bielefeld, Germany
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Baier M, Ströher E, Dietz KJ. The acceptor availability at photosystem I and ABA control nuclear expression of 2-Cys peroxiredoxin-A in Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2004; 45:997-1006. [PMID: 15356325 DOI: 10.1093/pcp/pch114] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The redox-regulated 2-Cys peroxiredoxin-A (2CPA) promoter, which drives expression of a dominant chloroplast antioxidant enzyme, responds to signals originating from the photosynthetic electron transport downstream of PSI. Modulation of CO(2)- and NO(3)(-) -reduction rates in reporter gene plants expressing glucuronidase under control of the Arabidopsis thaliana 2CPA promoter revealed that promoter activity correlates with the availability of electron acceptors at PSI. The photosynthetic redox-regulation can be simulated by oxidant and antioxidant treatments. Inhibitor studies with PD98059 and staurosporine showed that a mitogen-activated protein kinase kinase transmits the oxidative response, while the antioxidant signal is transmitted by a serine/threonine kinase. Analysis of 2CPA promoter regulation in the abscisic acid (ABA)-biosynthetic mutants aba2 and aba3 and the ABA-insensitive mutants abi1 and abi2 support a regulatory circuitry in which the redox signal cross-talks with the ABA-signaling cascade downstream of ABI1 and ABI2.
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Labate MTV, Ko K, Ko ZW, Pinto LSRC, Real MJUD, Romano MR, Barja PR, Granell A, Friso G, van Wijk KJ, Brugnoli E, Labate CA. Constitutive expression of pea Lhcb 1-2 in tobacco affects plant development, morphology and photosynthetic capacity. PLANT MOLECULAR BIOLOGY 2004; 55:701-14. [PMID: 15604711 DOI: 10.1007/s11103-004-1963-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Lhcb1-2 from pea was constitutively expressed in transgenic tobacco plants and assessed for functional impact. The successful assembly of the encoded proteins into LHCII trimers was confirmed by electrospray tandem mass spectrometry. Constitutive production of LHCb1-2 led to increased number of thylakoid membranes per chloroplast, increased grana stacking, higher chloroplast numbers per palisade cell and increased photosynthetic capacity at low irradiance, both on a chlorophyll and leaf area basis. The transgenic plants also displayed increased cell volume, larger leaves, higher leaf number per plant at flowering, increased biomass and increased seed weight, when grown under low irradiance levels. Under high irradiance, both transgenic and wild type plants displayed similar photosynthetic rates when tested at 25 degrees C; however, the non-photochemical quenching (NPQ) and qE values increased in the transgenic plants. The exposure of transgenic plants to a photoinhibitory treatment (4 degrees C for 4 h, under continuous illumination) resulted in more detrimental impairment of photosynthesis, since recovery was slower than the non-transgenic plants. These data indicate that constitutive expression of additional Lhcb1-2 transgenes led to a series of changes at all levels of the plant (cellular, leaf and whole organism), and a delay in flowering and senescence. The additional production of the pea protein appears to be accommodated by increasing cellular structures such as the number of thylakoids per chloroplast, organelle volume, organelles per cell, and leaf expansion. The presence of the trimeric pea protein in the tobacco LHCII, however, caused a possible change in the organization of the associated super-complex, that in turn limited photosynthesis at low temperature.
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Affiliation(s)
- Mônica T V Labate
- Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba-São Paulo, CP 83, CEP 13400-970 Brazil
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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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Dietz KJ. Redox control, redox signaling, and redox homeostasis in plant cells. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 228:141-93. [PMID: 14667044 DOI: 10.1016/s0074-7696(03)28004-9] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Redox chemistry is a key feature of life. Oxidized substrates are reduced to synthesize functional molecules; reduced substrates are oxidized for energy supply. In addition, cells must fight against uncontrolled oxidation of essential constituents, a process that continuously occurs in an atmosphere of 21% O2. The redox situation is further complicated in plants with their highly reactive photosynthetic metabolism. To this end it is now well established that redox regulation is a central element in adjusting plant metabolism and development to the prevailing environmental conditions. This review introduces general redox chemistry and the main components of the cellular redox network, namely pyridine nucleotides, ascorbate, glutathione, lipoic acid, tocopherol, thioredoxins, glutaredoxins, peroxiredoxins, and other thiol proteins. Examples for redox sensing, transduction, redox-regulated enzymes and transcription, and the function of regulatory circuits are presented. Emphasis is placed on redox regulation of photosynthesis, which is the best understood metabolism governed by redox control on essentially all levels, ranging from gene transcription to translation, assembly and turnover, as well as short-term adaptation by state transition and enzyme activity. Increasing evidence shows the importance of redox regulation in the context of transport, plant development, and programmed cell death.
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Affiliation(s)
- Karl-Josef Dietz
- Biochemistry and Physiology of Plants, W5-134, Faculty of Biology, University of Bielefeld, 33501 Bielefeld, Germany
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