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Smith MA, Benidickson KH, Plaxton WC. In Vivo Phosphorylation of the Cytosolic Glucose-6-Phosphate Dehydrogenase Isozyme G6PD6 in Phosphate-Resupplied Arabidopsis thaliana Suspension Cells and Seedlings. PLANTS (BASEL, SWITZERLAND) 2023; 13:31. [PMID: 38202338 PMCID: PMC10780934 DOI: 10.3390/plants13010031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/11/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024]
Abstract
Glucose-6-phosphate dehydrogenase (G6PD) catalyzes the first committed step of the oxidative pentose phosphate pathway (OPPP). Our recent phosphoproteomics study revealed that the cytosolic G6PD6 isozyme became hyperphosphorylated at Ser12, Thr13 and Ser18, 48 h following phosphate (Pi) resupply to Pi-starved (-Pi) Arabidopsis thaliana cell cultures. The aim of the present study was to assess whether G6PD6 phosphorylation also occurs in shoots or roots following Pi resupply to -Pi Arabidopsis seedlings, and to investigate its relationship with G6PD activity. Interrogation of phosphoproteomic databases indicated that N-terminal, multi-site phosphorylation of G6PD6 and its orthologs is quite prevalent. However, the functions of these phosphorylation events remain unknown. Immunoblotting with an anti-(pSer18 phosphosite-specific G6PD6) antibody confirmed that G6PD6 from Pi-resupplied, but not -Pi, Arabidopsis cell cultures or seedlings (i.e., roots) was phosphorylated at Ser18; this correlated with a significant increase in extractable G6PD activity, and biomass accumulation. Peptide kinase assays of Pi-resupplied cell culture extracts indicated that G6PD6 phosphorylation at Ser18 is catalyzed by a Ca2+-dependent protein kinase (CDPK), which correlates with the 'CDPK-like' targeting motif that flanks Ser18. Our results support the hypothesis that N-terminal phosphorylation activates G6PD6 to enhance OPPP flux and thus the production of reducing power (i.e., NADPH) and C-skeletons needed to establish the rapid resumption of growth that ensures Pi-resupply to -Pi Arabidopsis.
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Affiliation(s)
| | | | - William C. Plaxton
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada; (M.A.S.); (K.H.B.)
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2
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He JZ, Dorion S, Carmona-Rojas LM, Rivoal J. Carbon Fluxes in Potato ( Solanum tuberosum) Remain Stable in Cell Cultures Exposed to Nutritional Phosphate Deficiency. BIOLOGY 2023; 12:1190. [PMID: 37759596 PMCID: PMC10525292 DOI: 10.3390/biology12091190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 08/29/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023]
Abstract
Nutritional phosphate deficiency is a major limitation to plant growth. Here, we monitored fluxes in pathways supporting respiratory metabolism in potato (Solanum tuberosum) cell cultures growing in control or limiting phosphate conditions. Sugar uptake was quantified using [U-14C]sucrose as precursor. Carbohydrate degradation through glycolysis and respiratory pathways was estimated using the catabolism of [U-14C]sucrose to 14CO2. Anaplerotic carbon flux was assessed by labeling with NaH14CO3. The data showed that these metabolic fluxes displayed distinct patterns over culture time. However, phosphate depletion had relatively little impact on the various fluxes. Sucrose uptake was higher during the first six days of culture, followed by a decline, which was steeper in Pi-sufficient cells. Anaplerotic pathway flux was more important at day three and decreased thereafter. In contrast, the flux between sucrose and CO2 was at a maximum in the mid-log phase of the culture, with a peak at Day 6. Metabolization of [U-14C]sucrose into neutral, basic and acidic fractions was also unaffected by phosphate nutrition. Hence, the well-documented changes in central metabolism enzymes activities in response to Pi deficiency do not drastically modify metabolic fluxes, but rather result in the maintenance of the carbon fluxes that support respiration.
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Affiliation(s)
- Jiang Zhou He
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Rue Sherbrooke Est, Montréal, QC H1X 2B2, Canada; (J.Z.H.); (S.D.); (L.M.C.-R.)
| | - Sonia Dorion
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Rue Sherbrooke Est, Montréal, QC H1X 2B2, Canada; (J.Z.H.); (S.D.); (L.M.C.-R.)
| | - Laura Michell Carmona-Rojas
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Rue Sherbrooke Est, Montréal, QC H1X 2B2, Canada; (J.Z.H.); (S.D.); (L.M.C.-R.)
- Grupo de Biotecnologiía, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medelliín 050010, Colombia
| | - Jean Rivoal
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Rue Sherbrooke Est, Montréal, QC H1X 2B2, Canada; (J.Z.H.); (S.D.); (L.M.C.-R.)
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3
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Lingwan M, Shagun S, Pahwa F, Kumar A, Verma DK, Pant Y, Kamatam LVK, Kumari B, Nanda RK, Sunil S, Masakapalli SK. Phytochemical rich Himalayan Rhododendron arboreum petals inhibit SARS-CoV-2 infection in vitro. J Biomol Struct Dyn 2023; 41:1403-1413. [PMID: 34961411 DOI: 10.1080/07391102.2021.2021287] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Phytochemicals with potential to competitively bind to the host receptors or inhibit SARS-CoV-2 replication, may prove to be useful as adjunct therapeutics for COVID-19. We profiled and investigated the phytochemicals of Rhododendron arboreum petals sourced from Himalayan flora, undertook in vitro studies and found it as a promising candidate against SARS-CoV-2. The phytochemicals were reported in various scientific investigations to act against a range of virus in vitro and in vivo, which prompted us to test against SARS-CoV-2. In vitro assays of R. arboreum petals hot aqueous extract confirmed dose dependent reduction in SARS-CoV-2 viral load in infected Vero E6 cells (80% inhibition at 1 mg/ml; IC50 = 173 µg/ml) and phytochemicals profiled were subjected to molecular docking studies against SARS CoV-2 target proteins. The molecules 5-O-Feruloyl-quinic acid, 3-Caffeoyl-quinic acid, 5-O-Coumaroyl-D-quinic acid, Epicatechin and Catechin showed promising binding affinity with SARS-CoV-2 Main protease (MPro; PDB ID: 6LU7; responsible for viral replication) and Human Angiotensin Converting Enzyme-2 (ACE2; PDB ID: 1R4L; mediate viral entry in the host). Molecular dynamics (MD) simulation of 5-O-Feruloyl-quinic acid, an abundant molecule in the extract complexed with the target proteins showed stable interactions. Taken together, the phytochemical profiling, in silico analysis and in vitro anti-viral assay revealed that the petals extract act upon MPro and may be inhibiting SARS-CoV-2 replication. This is the first report highlighting R. arboreum petals as a reservoir of antiviral phytochemicals with potential anti-SARS-CoV-2 activity using an in vitro system.
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Affiliation(s)
- Maneesh Lingwan
- BioX Centre, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, India
| | - Shagun Shagun
- BioX Centre, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, India
| | - Falak Pahwa
- Translational Health Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Ankit Kumar
- Vector Borne Disease Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Dileep Kumar Verma
- Vector Borne Disease Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Yogesh Pant
- BioX Centre, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, India
| | - Lingarao V K Kamatam
- BioX Centre, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, India
| | - Bandna Kumari
- BioX Centre, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, India
| | - Ranjan Kumar Nanda
- Translational Health Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Sujatha Sunil
- Vector Borne Disease Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Shyam Kumar Masakapalli
- BioX Centre, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, India
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4
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Smith EN, Ratcliffe RG, Kruger NJ. Isotopically non-stationary metabolic flux analysis of heterotrophic Arabidopsis thaliana cell cultures. FRONTIERS IN PLANT SCIENCE 2023; 13:1049559. [PMID: 36699846 PMCID: PMC9868915 DOI: 10.3389/fpls.2022.1049559] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Fluxes are the ultimate phenotype of metabolism and their accurate quantification is fundamental to any understanding of metabolic networks. Steady state metabolic flux analysis has been the method of choice for quantifying fluxes in heterotrophic cells, but it is unable to measure fluxes during short-lived metabolic states, such as a transient oxidative load. Isotopically non-stationary metabolic flux analysis (INST-MFA) can be performed over shorter timescales (minutes - hours) and might overcome this limitation. INST-MFA has recently been applied to photosynthesising leaves, but agriculturally important tissues such as roots and storage organs, or plants during the night are heterotrophic. Here we outline the application of INST-MFA to heterotrophic plant cells. Using INST-MFA we were able to identify changes in the fluxes supported by phosphoenolpyruvate carboxylase and malic enzyme under oxidative load, highlighting the potential of INST-MFA to measure fluxes during short-lived metabolic states. We discuss the challenges in applying INST-MFA, and highlight further development required before it can be routinely used to quantify fluxes in heterotrophic plant cells.
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Affiliation(s)
- Edward N. Smith
- Molecular Plant Biology, Department of Biology, University of Oxford, Oxford, United Kingdom
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - R. George Ratcliffe
- Molecular Plant Biology, Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. Kruger
- Molecular Plant Biology, Department of Biology, University of Oxford, Oxford, United Kingdom
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Soumya PR, Vengavasi K, Pandey R. Adaptive strategies of plants to conserve internal phosphorus under P deficient condition to improve P utilization efficiency. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2022; 28:1981-1993. [PMID: 36573147 PMCID: PMC9789281 DOI: 10.1007/s12298-022-01255-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 11/17/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Phosphorus (P) is one of the limiting factors for plant growth and productivity due to its slow diffusion and immobilization in the soil which necessitates application of phosphatic fertilizers to meet the crop demand and obtain maximum yields. However, plants have evolved mechanisms to adapt to low P stress conditions either by increasing acquisition (alteration of belowground processes) or by internal inorganic P (Pi) utilization (cellular Pi homeostasis) or both. In this review, we have discussed the adaptive strategies that conserve the use of P and maintain cellular Pi homeostasis in the cytoplasm. These strategies involve modification in membrane lipid composition, flavanol/anthocyanin level, scavenging and reutilization of Pi adsorbed in cell wall pectin, remobilization of Pi during senescence by enzymes like RNases and purple acid phosphatases, alternative mitochondrial electron transport, and glycolytic pathways. The remobilization of Pi from senescing tissues and its internal redistribution to various cellular organelles is mediated by various Pi transporters. Although much efforts have been made to enhance P acquisition efficiency, an understanding of the physiological mechanisms conserving internal Pi and their manipulation would be useful for plants that can utilize P more efficiently to produce optimum growth per unit P uptake.
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Affiliation(s)
- Preman R. Soumya
- Mineral Nutrition Laboratory, Division of Plant Physiology, ICAR-Indian Agricultural Research Institute, New Delhi, 110 012 India
- Present Address: Regional Agricultural Research Station, Kerala Agricultural University, Ambalavayal, Wayanad, Kerala 673593 India
| | - Krishnapriya Vengavasi
- Division of Crop Production, ICAR-Sugarcane Breeding Institute, Coimbatore, Tamil Nadu 641007 India
| | - Renu Pandey
- Mineral Nutrition Laboratory, Division of Plant Physiology, ICAR-Indian Agricultural Research Institute, New Delhi, 110 012 India
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6
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Jindal S, Iyer MS, Jyoti P, Masakapalli SK, Venkatesh KV. Mutants lacking global regulators, fis and arcA, in Escherichia coli enhanced growth fitness under acetate metabolism by pathway reprogramming. Appl Microbiol Biotechnol 2022; 106:3231-3243. [PMID: 35416487 DOI: 10.1007/s00253-022-11890-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 03/20/2022] [Accepted: 03/21/2022] [Indexed: 11/25/2022]
Abstract
Global regulatory transcription factors play a significant role in controlling microbial metabolism under genetic and environmental perturbations. A system-level effect of carbon sources such as acetate on microbial metabolism under disrupted global regulators has not been well established. Acetate is one of the major substrates available in various nutrient niches such as the mammalian gut and a keto diet. A substantial amount of acetate gets secreted in aerobic metabolism. Therefore, investigating the study on acetate metabolism is highly significant. It is known that the global regulators fis and arcA regulate acetate uptake genes in E. coli under glucose conditions. This study deciphered the growth and flux distribution of E. coli transcription regulatory knockouts Δfis, ΔarcA and double deletion mutant, ΔarcAΔfis under acetate using 13C-metabolic flux analysis (MFA), which has not been investigated before. We observed that the mutants exhibited an expeditious growth rate (~ 1.2-1.6-fold) with a proportionate increase in acetate uptake rates compared to the wild type. 13C-MFA displayed the distinct metabolic reprogramming of intracellular fluxes via the TCA cycle, anaplerotic pathway and gluconeogenesis, which conferred an advantage of a faster growth rate with better carbon usage in all the mutants. This resulted in higher metabolic fluxes through the TCA cycle (~ 18-90%), lower gluconeogenesis (~ 15-35%) and higher CO2 and ATP production with the proportional increase in growth rate. The study reveals a novel insight by stating the sub-optimality of the wild-type strain grown under acetate substrate aerobically. These mutant strains efficiently oxidize acetate, thus acting as potential candidates for the biosynthesis of isoprenoids, biofuels, vitamins and various pharmaceutical products.Key Points• Mutants exhibited a better balance between energy and precursor synthesis than WT.• Leveraged in the unravelling of regulatory control under various nutrient shifts.• Metabolic readjustment resulted in optimal biomass requirement and faster growth.
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Affiliation(s)
- Shikha Jindal
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Mahesh S Iyer
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Poonam Jyoti
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, 175075, India
| | - Shyam Kumar Masakapalli
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, 175075, India.
| | - K V Venkatesh
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
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7
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Lingwan M, Masakapalli SK. A robust method of extraction and GC-MS analysis of Monophenols exhibited UV-B mediated accumulation in Arabidopsis. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2022; 28:533-543. [PMID: 35400881 PMCID: PMC8943066 DOI: 10.1007/s12298-022-01150-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 02/12/2022] [Accepted: 02/16/2022] [Indexed: 05/20/2023]
Abstract
UNLABELLED Studies on specialized metabolites like phenolics are of immense interest owing to their significance to agriculture, nutrition and health. In plants, phenolics accumulate and exhibit spatial and temporal regulations in response to growth conditions. Robust methodologies aimed at efficient extraction of plant phenolics, their qualitative and quantitative analysis is desired. We optimized the analytical and experimental bottlenecks that captured free, ester, glycoside and wall-bound phenolics after acid or alkali treatments of the tissue extracts and subsequent GC-MS analysis. Higher recovery of phenolics from the methanolic extracts was achieved through (a) Ultrasonication assisted extraction along with Methyl tert-butyl ether (MTBE) enrichment (b) nitrogen gas drying and (c) their derivatization using MSTFA for GC-MS analysis. The optimized protocol was tested on Arabidopsis rosette exposed to UV-B radiation (280-315 nm) which triggered enhanced levels of 11 monophenols and might be attributed to photoprotection and other physiological roles. Interestingly, coumaric acid (308 m/z) and caffeic acid (396 m/z) levels were enhanced by 12-14 folds under UV-B. Other phenolics such as cinnamic acid (220 m/z), hydroxybenzoic acid (282 m/z), vanillic acid (312 m/z, gallic acid (458 m/z), ferulic acid (338 m/z), benzoic acid (194 m/z), sinapinic acid (368 m/z) and protocatechuic acid (370 m/z) also showed elevated levels by about 1 to 4 folds. The protocol also comprehensively captured the variations in the levels of ester, glycoside and wall-bounded phenolics with high reproducibility and sensitivity. The robust method of extraction and GC-MS analysis can readily be adopted for studying phenolics in plant systems. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s12298-022-01150-2.
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Affiliation(s)
- Maneesh Lingwan
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, 175075 Kamand, Himachal Pradesh India
| | - Shyam Kumar Masakapalli
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, 175075 Kamand, Himachal Pradesh India
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Dellero Y, Berardocco S, Berges C, Filangi O, Bouchereau A. Validation of carbon isotopologue distribution measurements by GC-MS and application to 13C-metabolic flux analysis of the tricarboxylic acid cycle in Brassica napus leaves. FRONTIERS IN PLANT SCIENCE 2022; 13:885051. [PMID: 36704152 PMCID: PMC9871494 DOI: 10.3389/fpls.2022.885051] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 11/28/2022] [Indexed: 05/14/2023]
Abstract
The estimation of metabolic fluxes in photosynthetic organisms represents an important challenge that has gained interest over the last decade with the development of 13C-Metabolic Flux Analysis at isotopically non-stationary steady-state. This approach requires a high level of accuracy for the measurement of Carbon Isotopologue Distribution in plant metabolites. But this accuracy has still not been evaluated at the isotopologue level for GC-MS, leading to uncertainties for the metabolic fluxes calculated based on these fragments. Here, we developed a workflow to validate the measurements of CIDs from plant metabolites with GC-MS by producing tailor-made E. coli standard extracts harboring a predictable binomial CID for some organic and amino acids. Overall, most of our TMS-derivatives mass fragments were validated with these standards and at natural isotope abundance in plant matrices. Then, we applied this validated MS method to investigate the light/dark regulation of plant TCA cycle by incorporating U-13C-pyruvate to Brassica napus leaf discs. We took advantage of pathway-specific isotopologues/isotopomers observed between two and six hours of labeling to show that the TCA cycle can operate in a cyclic manner under both light and dark conditions. Interestingly, this forward cyclic flux mode has a nearly four-fold higher contribution for pyruvate-to-citrate and pyruvate-to-malate fluxes than the phosphoenolpyruvate carboxylase (PEPc) flux reassimilating carbon derived from some mitochondrial enzymes. The contribution of stored citrate to the mitochondrial TCA cycle activity was also questioned based on dynamics of 13C-enrichment in citrate, glutamate and succinate and variations of citrate total amounts under light and dark conditions. Interestingly, there was a light-dependent 13C-incorporation into glycine and serine showing that decarboxylations from pyruvate dehydrogenase complex and TCA cycle enzymes were actively reassimilated and could represent up to 5% to net photosynthesis.
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Affiliation(s)
- Younès Dellero
- Institute for Genetics, Environment and Plant Protection (IGEPP), National Research Institute for Agriculture, Food and Environment (INRAE), Université Rennes, Institut Agro, Le Rheu, France
- Metabolic Profiling and Metabolomics platform (P2M2), Institute for Genetics, Environment and Plant Protection (IGEPP), Biopolymers Interactions Assemblies (BIA), Le Rheu, France
- MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France
- *Correspondence: Younès Dellero,
| | - Solenne Berardocco
- Institute for Genetics, Environment and Plant Protection (IGEPP), National Research Institute for Agriculture, Food and Environment (INRAE), Université Rennes, Institut Agro, Le Rheu, France
- Metabolic Profiling and Metabolomics platform (P2M2), Institute for Genetics, Environment and Plant Protection (IGEPP), Biopolymers Interactions Assemblies (BIA), Le Rheu, France
| | - Cécilia Berges
- MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France
- Toulouse Biotechnology Institute, Université de Toulouse, National center for Scientific Research (CNRS), National Institute for Research for Agriculture, Food and Environment (INRAE), National Institute of Applied Sciences (INSA), Toulouse, France
| | - Olivier Filangi
- Institute for Genetics, Environment and Plant Protection (IGEPP), National Research Institute for Agriculture, Food and Environment (INRAE), Université Rennes, Institut Agro, Le Rheu, France
- Metabolic Profiling and Metabolomics platform (P2M2), Institute for Genetics, Environment and Plant Protection (IGEPP), Biopolymers Interactions Assemblies (BIA), Le Rheu, France
- MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France
| | - Alain Bouchereau
- Institute for Genetics, Environment and Plant Protection (IGEPP), National Research Institute for Agriculture, Food and Environment (INRAE), Université Rennes, Institut Agro, Le Rheu, France
- Metabolic Profiling and Metabolomics platform (P2M2), Institute for Genetics, Environment and Plant Protection (IGEPP), Biopolymers Interactions Assemblies (BIA), Le Rheu, France
- MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France
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9
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Smith EN, Schwarzländer M, Ratcliffe RG, Kruger NJ. Shining a light on NAD- and NADP-based metabolism in plants. TRENDS IN PLANT SCIENCE 2021; 26:1072-1086. [PMID: 34281784 DOI: 10.1016/j.tplants.2021.06.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 05/20/2023]
Abstract
The pyridine nucleotides nicotinamide adenine dinucleotide [NAD(H)] and nicotinamide adenine dinucleotide phosphate [NADP(H)] simultaneously act as energy transducers, signalling molecules, and redox couples. Recent research into photosynthetic optimisation, photorespiration, immunity, hypoxia/oxygen signalling, development, and post-harvest metabolism have all identified pyridine nucleotides as key metabolites. Further understanding will require accurate description of NAD(P)(H) metabolism, and genetically encoded fluorescent biosensors have recently become available for this purpose. Although these biosensors have begun to provide novel biological insights, their limitations must be considered and the information they provide appropriately interpreted. We provide a framework for understanding NAD(P)(H) metabolism and explore what fluorescent biosensors can, and cannot, tell us about plant biology, looking ahead to the pressing questions that could be answered with further development of these tools.
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Affiliation(s)
- Edward N Smith
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK; Current address: Department of Molecular Systems Biology, University of Groningen, 9747 AG Groningen, The Netherlands.
| | - Markus Schwarzländer
- Institute of Plant Biology and Biotechnology (IBBP), Westfälische Wilhelms-Universität Münster, D-48143 Münster, Germany
| | | | - Nicholas J Kruger
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
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10
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Jyoti P, Patil N, Masakapalli SK. Insights into the Polyhydroxybutyrate Biosynthesis in Ralstonia solanacearum Using Parallel 13C Tracers and Comparative Genome Analysis. ACS Chem Biol 2021; 16:1215-1222. [PMID: 34143620 DOI: 10.1021/acschembio.1c00249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bacterial accumulation of poly(3-hydroxybutyrate) [P(3HB)] is a metabolic strategy often adopted to cope with challenging surroundings. Ralstonia solanacearum, a phytopathogen, seems to be an ideal candidate with inherent ability to accumulate this biodegradable polymer of high industrial relevance. This study is focused on investigating the metabolic networks that channel glucose into P(3HB) using comparative genome analysis, 13C tracers, microscopy, gas chromatography-mass spectrometry (GC-MS), and proton nuclear magnetic resonance (1H NMR). Comparative genome annotation of 87 R. solanacearum strains confirmed the presence of a conserved P(3HB) biosynthetic pathway genes in the chromosome. Parallel 13C glucose feeding ([1-13C], [1,2-13C]) analysis mapped the glucose oxidation to 3-hydroxybutyrate (3HB), the metabolic precursor of P(3HB) via the Entner-Doudoroff pathway (ED pathway), potentially to meet the NADPH demands. Fluorescence microscopy, GC-MS, and 1H NMR analysis further confirmed the ability of R. solanacearum to accumulate P(3HB) granules. In addition, it is demonstrated that the carbon/nitrogen (C/N) ratio influences the P(3HB) yields, thereby highlighting the need to further optimize the bioprocessing parameters. This study provided key insights into the biosynthetic abilities of R. solanacearum as a promising P(3HB) producer.
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Affiliation(s)
- Poonam Jyoti
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand 175075, Himachal Pradesh, India
| | - Nitin Patil
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand 175075, Himachal Pradesh, India
| | - Shyam Kumar Masakapalli
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand 175075, Himachal Pradesh, India
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11
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Carrera DÁ, George GM, Fischer-Stettler M, Galbier F, Eicke S, Truernit E, Streb S, Zeeman SC. Distinct plastid fructose bisphosphate aldolases function in photosynthetic and non-photosynthetic metabolism in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:3739-3755. [PMID: 33684221 PMCID: PMC8628874 DOI: 10.1093/jxb/erab099] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 03/01/2021] [Indexed: 05/31/2023]
Abstract
Plastid metabolism is critical in both photoautotrophic and heterotrophic plant cells. In chloroplasts, fructose-1,6-bisphosphate aldolase (FBA) catalyses the formation of both fructose 1,6-bisphosphate and sedoheptulose 1,7-bisphosphate within the Calvin-Benson cycle. Three Arabidopsis genes, AtFBA1-AtFBA3, encode plastidial isoforms of FBA, but the contribution of each isoform is unknown. Phylogenetic analysis indicates that FBA1 and FBA2 derive from a recently duplicated gene, while FBA3 is a more ancient paralog. fba1 mutants are phenotypically indistinguishable from the wild type, while both fba2 and fba3 have reduced growth. We show that FBA2 is the major isoform in leaves, contributing most of the measurable activity. Partial redundancy with FBA1 allows both single mutants to survive, but combining both mutations is lethal, indicating a block of photoautotrophy. In contrast, FBA3 is expressed predominantly in heterotrophic tissues, especially the leaf and root vasculature, but not in the leaf mesophyll. We show that the loss of FBA3 affects plastidial glycolytic metabolism of the root, potentially limiting the biosynthesis of essential compounds such as amino acids. However, grafting experiments suggest that fba3 is dysfunctional in leaf phloem transport, and we suggest that a block in photoassimilate export from leaves causes the buildup of high carbohydrate concentrations and retarded growth.
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Affiliation(s)
| | - Gavin M George
- Department of Biology, ETH Zurich, 8092
Zurich, Switzerland
| | | | | | - Simona Eicke
- Department of Biology, ETH Zurich, 8092
Zurich, Switzerland
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12
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Dissanayaka DMSB, Ghahremani M, Siebers M, Wasaki J, Plaxton WC. Recent insights into the metabolic adaptations of phosphorus-deprived plants. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:199-223. [PMID: 33211873 DOI: 10.1093/jxb/eraa482] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 10/13/2020] [Indexed: 06/11/2023]
Abstract
Inorganic phosphate (Pi) is an essential macronutrient required for many fundamental processes in plants, including photosynthesis and respiration, as well as nucleic acid, protein, and membrane phospholipid synthesis. The huge use of Pi-containing fertilizers in agriculture demonstrates that the soluble Pi levels of most soils are suboptimal for crop growth. This review explores recent advances concerning the understanding of adaptive metabolic processes that plants have evolved to alleviate the negative impact of nutritional Pi deficiency. Plant Pi starvation responses arise from complex signaling pathways that integrate altered gene expression with post-transcriptional and post-translational mechanisms. The resultant remodeling of the transcriptome, proteome, and metabolome enhances the efficiency of root Pi acquisition from the soil, as well as the use of assimilated Pi throughout the plant. We emphasize how the up-regulation of high-affinity Pi transporters and intra- and extracellular Pi scavenging and recycling enzymes, organic acid anion efflux, membrane remodeling, and the remarkable flexibility of plant metabolism and bioenergetics contribute to the survival of Pi-deficient plants. This research field is enabling the development of a broad range of innovative and promising strategies for engineering phosphorus-efficient crops. Such cultivars are urgently needed to reduce inputs of unsustainable and non-renewable Pi fertilizers for maximum agronomic benefit and long-term global food security and ecosystem preservation.
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Affiliation(s)
- D M S B Dissanayaka
- Department of Crop Science, Faculty of Agriculture, University of Peradeniya, Peradeniya, Sri Lanka
- Graduate School of Biosphere Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan
| | - Mina Ghahremani
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Meike Siebers
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg, Cologne, Germany
- Institute of Plant Genetics, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Jun Wasaki
- Graduate School of Biosphere Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan
- Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan
| | - William C Plaxton
- Department of Biology, Queen's University, Kingston, Ontario, Canada
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13
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Mehta D, Ghahremani M, Pérez-Fernández M, Tan M, Schläpfer P, Plaxton WC, Uhrig RG. Phosphate and phosphite have a differential impact on the proteome and phosphoproteome of Arabidopsis suspension cell cultures. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:924-941. [PMID: 33184936 DOI: 10.1111/tpj.15078] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/01/2020] [Accepted: 10/19/2020] [Indexed: 05/21/2023]
Abstract
Phosphorus absorbed in the form of phosphate (H2 PO4- ) is an essential but limiting macronutrient for plant growth and agricultural productivity. A comprehensive understanding of how plants respond to phosphate starvation is essential for the development of more phosphate-efficient crops. Here we employed label-free proteomics and phosphoproteomics to quantify protein-level responses to 48 h of phosphate versus phosphite (H2 PO3- ) resupply to phosphate-deprived Arabidopsis thaliana suspension cells. Phosphite is similarly sensed, taken up and transported by plant cells as phosphate, but cannot be metabolized or used as a nutrient. Phosphite is thus a useful tool for differentiating between non-specific processes related to phosphate sensing and transport and specific responses to phosphorus nutrition. We found that responses to phosphate versus phosphite resupply occurred mainly at the level of protein phosphorylation, complemented by limited changes in protein abundance, primarily in protein translation, phosphate transport and scavenging, and central metabolism proteins. Altered phosphorylation of proteins involved in core processes such as translation, RNA splicing and kinase signaling was especially important. We also found differential phosphorylation in response to phosphate and phosphite in 69 proteins, including splicing factors, translation factors, the PHT1;4 phosphate transporter and the HAT1 histone acetyltransferase - potential phospho-switches signaling changes in phosphorus nutrition. Our study illuminates several new aspects of the phosphate starvation response and identifies important targets for further investigation and potential crop improvement.
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Affiliation(s)
- Devang Mehta
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, AB, T6G 2E9, Canada
| | - Mina Ghahremani
- Department of Biology, Queen's University, 116 Barrie St., Kingston, ON, K7L 3N6, Canada
| | - Maria Pérez-Fernández
- Departamento de Sistemas Físicos Químicos y Naturales, Universidad Pablo de Olavide, Ecology Area. Faculty os Experimental Sciences. Carretera de Utrera Km 1, Sevilla, 41013, Spain
| | - Maryalle Tan
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, AB, T6G 2E9, Canada
| | - Pascal Schläpfer
- Department of Biology, Institute of Molecular Plant Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - William C Plaxton
- Department of Biology, Queen's University, 116 Barrie St., Kingston, ON, K7L 3N6, Canada
| | - R Glen Uhrig
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, AB, T6G 2E9, Canada
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14
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Bhatia M, Thakur J, Suyal S, Oniel R, Chakraborty R, Pradhan S, Sharma M, Sengupta S, Laxman S, Masakapalli SK, Bachhawat AK. Allosteric inhibition of MTHFR prevents futile SAM cycling and maintains nucleotide pools in one-carbon metabolism. J Biol Chem 2020; 295:16037-16057. [PMID: 32934008 PMCID: PMC7681022 DOI: 10.1074/jbc.ra120.015129] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/12/2020] [Indexed: 01/05/2023] Open
Abstract
Methylenetetrahydrofolate reductase (MTHFR) links the folate cycle to the methionine cycle in one-carbon metabolism. The enzyme is known to be allosterically inhibited by SAM for decades, but the importance of this regulatory control to one-carbon metabolism has never been adequately understood. To shed light on this issue, we exchanged selected amino acid residues in a highly conserved stretch within the regulatory region of yeast MTHFR to create a series of feedback-insensitive, deregulated mutants. These were exploited to investigate the impact of defective allosteric regulation on one-carbon metabolism. We observed a strong growth defect in the presence of methionine. Biochemical and metabolite analysis revealed that both the folate and methionine cycles were affected in these mutants, as was the transsulfuration pathway, leading also to a disruption in redox homeostasis. The major consequences, however, appeared to be in the depletion of nucleotides. 13C isotope labeling and metabolic studies revealed that the deregulated MTHFR cells undergo continuous transmethylation of homocysteine by methyltetrahydrofolate (CH3THF) to form methionine. This reaction also drives SAM formation and further depletes ATP reserves. SAM was then cycled back to methionine, leading to futile cycles of SAM synthesis and recycling and explaining the necessity for MTHFR to be regulated by SAM. The study has yielded valuable new insights into the regulation of one-carbon metabolism, and the mutants appear as powerful new tools to further dissect out the intersection of one-carbon metabolism with various pathways both in yeasts and in humans.
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Affiliation(s)
- Muskan Bhatia
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, S.A.S. Nagar, Punjab, India
| | - Jyotika Thakur
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, India
| | - Shradha Suyal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, S.A.S. Nagar, Punjab, India
| | - Ruchika Oniel
- Institute for Stem Cell Science and Regenerative Medicine (inStem), NCBS-TIFR Campus, Bangalore, India
| | - Rahul Chakraborty
- Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Shalini Pradhan
- Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Monika Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, S.A.S. Nagar, Punjab, India
| | - Shantanu Sengupta
- Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine (inStem), NCBS-TIFR Campus, Bangalore, India
| | - Shyam Kumar Masakapalli
- BioX Center, School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, India
| | - Anand Kumar Bachhawat
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, S.A.S. Nagar, Punjab, India.
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Tivendale ND, Hanson AD, Henry CS, Hegeman AD, Millar AH. Enzymes as Parts in Need of Replacement - and How to Extend Their Working Life. TRENDS IN PLANT SCIENCE 2020; 25:661-669. [PMID: 32526171 DOI: 10.1016/j.tplants.2020.02.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 06/11/2023]
Abstract
Enzymes catalyze reactions in vivo at different rates and each enzyme molecule has a lifetime limit before it is degraded and replaced to enable catalysis to continue. Considering these rates together as a unitless ratio of catalytic cycles until replacement (CCR) provides a new quantitative tool to assess the replacement schedule of and energy investment into enzymes as they relate to function. Here, we outline the challenges of determining CCRs and new approaches to overcome them and then assess the CCRs of selected enzymes in bacteria and plants to reveal a range of seven orders of magnitude for this ratio. Modifying CCRs in plants holds promise to lower cellular costs, to tailor enzymes for particular environments, and to breed enzyme improvements for crop productivity.
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Affiliation(s)
- Nathan D Tivendale
- ARC Centre for Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, M316, Perth, WA 6009, Australia
| | - Andrew D Hanson
- Horticultural Sciences Department, University of Florida, PO Box 110690, Gainesville, FL 32611-0690, USA
| | - Christopher S Henry
- Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439, USA; Computation Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Adrian D Hegeman
- Department of Horticultural Science, Department of Plant and Microbial Biology, and The Microbial and Plant Genomics Institute, University of Minnesota, 1970 Folwell Avenue, Saint Paul, MN 55108-6007, USA
| | - A Harvey Millar
- ARC Centre for Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, M316, Perth, WA 6009, Australia.
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The Entner-Doudoroff and Nonoxidative Pentose Phosphate Pathways Bypass Glycolysis and the Oxidative Pentose Phosphate Pathway in Ralstonia solanacearum. mSystems 2020; 5:5/2/e00091-20. [PMID: 32156794 PMCID: PMC7065512 DOI: 10.1128/msystems.00091-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Understanding the metabolic versatility of Ralstonia solanacearum is important, as it regulates the trade-off between virulence and metabolism (1, 2) in a wide range of plant hosts. Due to a lack of clear evidence until this work, several published research papers reported on the potential roles of glycolysis and the oxidative pentose phosphate pathway (OxPPP) in R. solanacearum (3, 4). This work provided evidence from 13C stable isotope feeding and genome annotation-based comparative metabolic network analysis that the Entner-Doudoroff pathway and non-OxPPP bypass glycolysis and OxPPP during the oxidation of glucose, a component of the host xylem pool that serves as a potential carbon source (5). The outcomes help better define the central carbon metabolic network of R. solanacearum that can be integrated with 13C metabolic flux analysis as well as flux balance analysis studies for defining the metabolic phenotypes. The study highlights the need to critically examine phytopathogens whose metabolism is poorly understood. In Ralstonia solanacearum, a devastating phytopathogen whose metabolism is poorly understood, we observed that the Entner-Doudoroff (ED) pathway and nonoxidative pentose phosphate pathway (non-OxPPP) bypass glycolysis and OxPPP under glucose oxidation. Evidence derived from 13C stable isotope feeding and genome annotation-based comparative metabolic network analysis supported the observations. Comparative metabolic network analysis derived from the currently available 53 annotated R. solanacearum strains, including a recently reported strain (F1C1), representing the four phylotypes, confirmed the lack of key genes coding for phosphofructokinase (pfk-1) and phosphogluconate dehydrogenase (gnd) enzymes that are relevant for glycolysis and OxPPP, respectively. R. solanacearum F1C1 cells fed with [13C]glucose (99% [1-13C]glucose or 99% [1,2-13C]glucose or 40% [13C6]glucose) followed by gas chromatography-mass spectrometry (GC-MS)-based labeling analysis of fragments from amino acids, glycerol, and ribose provided clear evidence that rather than glycolysis and the OxPPP, the ED pathway and non-OxPPP are the main routes sustaining metabolism in R. solanacearum. The 13C incorporation in the mass ions of alanine (m/z 260 and m/z 232), valine (m/z 288 and m/z 260), glycine (m/z 218), serine (m/z 390 and m/z 362), histidine (m/z 440 and m/z 412), tyrosine (m/z 466 and m/z 438), phenylalanine (m/z 336 and m/z 308), glycerol (m/z 377), and ribose (m/z 160) mapped the pathways supporting the observations. The outcomes help better define the central carbon metabolic network of R. solanacearum that can be integrated with 13C metabolic flux analysis as well as flux balance analysis studies for defining the metabolic phenotypes. IMPORTANCE Understanding the metabolic versatility of Ralstonia solanacearum is important, as it regulates the trade-off between virulence and metabolism (1, 2) in a wide range of plant hosts. Due to a lack of clear evidence until this work, several published research papers reported on the potential roles of glycolysis and the oxidative pentose phosphate pathway (OxPPP) in R. solanacearum (3, 4). This work provided evidence from 13C stable isotope feeding and genome annotation-based comparative metabolic network analysis that the Entner-Doudoroff pathway and non-OxPPP bypass glycolysis and OxPPP during the oxidation of glucose, a component of the host xylem pool that serves as a potential carbon source (5). The outcomes help better define the central carbon metabolic network of R. solanacearum that can be integrated with 13C metabolic flux analysis as well as flux balance analysis studies for defining the metabolic phenotypes. The study highlights the need to critically examine phytopathogens whose metabolism is poorly understood.
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Allen DK, Young JD. Tracing metabolic flux through time and space with isotope labeling experiments. Curr Opin Biotechnol 2019; 64:92-100. [PMID: 31864070 PMCID: PMC7302994 DOI: 10.1016/j.copbio.2019.11.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 11/02/2019] [Accepted: 11/04/2019] [Indexed: 12/11/2022]
Abstract
Metabolism is dynamic and must function in context-specific ways to adjust to changes in the surrounding cellular and ecological environment. When isotopic tracers are used, metabolite flow (i.e. metabolic flux) can be quantified through biochemical networks to assess metabolic pathway operation. The cellular activities considered across multiple tissues and organs result in the observed phenotype and can be analyzed to discover emergent, whole-system properties of biology and elucidate misconceptions about network operation. However, temporal and spatial challenges remain significant hurdles and require novel approaches and creative solutions. We survey current investigations in higher plant and animal systems focused on dynamic isotope labeling experiments, spatially resolved measurement strategies, and observations from re-analysis of our own studies that suggest prospects for future work. Related discoveries will be necessary to push the frontier of our understanding of metabolism to suggest novel solutions to cure disease and feed a growing future world population.
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Affiliation(s)
- Doug K Allen
- United States Department of Agriculture-Agricultural Research Service, Plant Genetics Research Unit, 975 North Warson Road, St. Louis, MO 63132, United States; Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, United States.
| | - Jamey D Young
- Department of Chemical & Biomolecular Engineering, Vanderbilt University, PMB 351604, 2301 Vanderbilt Place, Nashville, TN 37235, United States; Department of Molecular Physiology & Biophysics, Vanderbilt University, PMB 351604, 2301 Vanderbilt Place, Nashville, TN 37235, United States.
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18
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Limitations of Deuterium-Labelled Substrates for Quantifying NADPH Metabolism in Heterotrophic Arabidopsis Cell Cultures. Metabolites 2019; 9:metabo9100205. [PMID: 31569392 PMCID: PMC6835633 DOI: 10.3390/metabo9100205] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/19/2019] [Accepted: 09/26/2019] [Indexed: 01/21/2023] Open
Abstract
NADPH is the primary source of cellular reductant for biosynthesis, and strategies for increasing productivity via metabolic engineering need to take account of the requirement for reducing power. In plants, while the oxidative pentose phosphate pathway is the most direct route for NADPH production in heterotrophic tissues, there is increasing evidence that other pathways make significant contributions to redox balance. Deuterium-based isotopic labelling strategies have recently been developed to quantify the relative production of NADPH from different pathways in mammalian cells, but the application of these methods to plants has not been critically evaluated. In this study, LC-MS was used to measure deuterium incorporation into metabolites extracted from heterotrophic Arabidopsis cell cultures grown on [1-2H]glucose or D2O. The results show that a high rate of flavin-enzyme-catalysed water exchange obscures labelling of NADPH from deuterated substrates and that this exchange cannot be accurately accounted for due to exchange between triose- and hexose-phosphates. In addition, the duplication of NADPH generating reactions between subcellular compartments can confound analysis based on whole cell extracts. Understanding how the structure of the metabolic network affects the applicability of deuterium labelling methods is a prerequisite for development of more effective flux determination strategies, ensuring data are both quantitative and representative of endogenous biological processes.
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19
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He JZ, Dorion S, Lacroix M, Rivoal J. Sustained substrate cycles between hexose phosphates and free sugars in phosphate-deficient potato (Solanum tuberosum) cell cultures. PLANTA 2019; 249:1319-1336. [PMID: 30627889 DOI: 10.1007/s00425-019-03088-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 01/03/2019] [Indexed: 06/09/2023]
Abstract
Futile cycling between free sugars and hexose phosphates occurring under phosphate deficiency could be involved in the maintenance of a threshold level of free cellular phosphate to preserve respiratory metabolism. We studied the metabolic response of potato cell cultures growing in Pi sufficient (2.5 mM, +Pi) or deficient (125 µM, -Pi) conditions. Under Pi deficiency, cellular growth was severely affected, however -Pi cells were able to maintain a low but steady level of free Pi. We surveyed the activities of 33 primary metabolic enzymes during the course of a 12 days Pi deficiency period. Our results show that many of these enzymes had higher specific activity in -Pi cells. Among these, we found typical markers of Pi deficiency such as phosphoenolpyruvate phosphatase and phosphoenolpyruvate carboxylase as well as enzymes involved in the biosynthesis of organic acids. Intriguingly, several ATP-consuming enzymes such as hexokinase (HK) and phosphofructokinase also displayed increased activity in -Pi condition. For HK, this was associated with an increase in the steady state of a specific HK polypeptide. Quantification of glycolytic intermediates showed a pronounced decrease in phosphate esters under Pi deficiency. Adenylate levels also decreased in -Pi cells, but the Adenylate Energy Charge was not affected by the treatment. To investigate the significance of HK induction under low Pi, [U-14C]-glucose tracer studies were conducted. We found in vivo evidence of futile cycling between pools of hexose phosphates and free sugars under Pi deficiency. Our study suggests that the futile cycling between hexose phosphates and free sugars which is active under +Pi conditions is sustained under Pi deficiency. The possibility that this process represents a metabolic adaptation to Pi deficiency is discussed with respect to Pi homeostasis in Pi-deficient conditions.
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Affiliation(s)
- Jiang Zhou He
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke est, Montréal, Qc, H1X 2B2, Canada
| | - Sonia Dorion
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke est, Montréal, Qc, H1X 2B2, Canada
| | - Mélanie Lacroix
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke est, Montréal, Qc, H1X 2B2, Canada
| | - Jean Rivoal
- Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke est, Montréal, Qc, H1X 2B2, Canada.
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O'Leary BM, Asao S, Millar AH, Atkin OK. Core principles which explain variation in respiration across biological scales. THE NEW PHYTOLOGIST 2019; 222:670-686. [PMID: 30394553 DOI: 10.1111/nph.15576] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 10/18/2018] [Indexed: 05/02/2023]
Abstract
Contents Summary 670 I. Introduction 671 II. Principle 1 - Plant respiration performs three distinct functions 673 III. Principle 2 - Metabolic pathway flexibility underlies plant respiratory performance 676 IV. Principle 3 - Supply and demand interact over time to set plant respiration rate 677 V. Principle 4 - Plant respiratory acclimation involves adjustments in enzyme capacities 679 VI. Principle 5 - Respiration is a complex trait that helps to define, and is impacted by, plant lifestyle strategies 680 VII. Future directions 680 Acknowledgements 682 References 682 SUMMARY: Respiration is a core biological process that has important implications for the biochemistry, physiology, and ecology of plants. The study of plant respiration is thus conducted from several different perspectives by a range of scientific disciplines with dissimilar objectives, such as metabolic engineering, crop breeding, and climate-change modelling. One aspect in common among the different objectives is a need to understand and quantify the variation in respiration across scales of biological organization. The central tenet of this review is that different perspectives on respiration can complement each other when connected. To better accommodate interdisciplinary thinking, we identify distinct mechanisms which encompass the variation in respiratory rates and functions across biological scales. The relevance of these mechanisms towards variation in plant respiration are explained in the context of five core principles: (1) respiration performs three distinct functions; (2) metabolic pathway flexibility underlies respiratory performance; (3) supply and demand interact over time to set respiration rates; (4) acclimation involves adjustments in enzyme capacities; and (5) respiration is a complex trait that helps to define, and is impacted by, plant lifestyle strategies. We argue that each perspective on respiration rests on these principles to varying degrees and that broader appreciation of how respiratory variation occurs can unite research across scales.
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Affiliation(s)
- Brendan M O'Leary
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia
| | - Shinichi Asao
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
| | - A Harvey Millar
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia
| | - Owen K Atkin
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
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Yadav A, Lingwan M, Yadukrishnan P, Masakapalli SK, Datta S. BBX31 promotes hypocotyl growth, primary root elongation and UV-B tolerance in Arabidopsis. PLANT SIGNALING & BEHAVIOR 2019; 14:e1588672. [PMID: 30835612 PMCID: PMC6512910 DOI: 10.1080/15592324.2019.1588672] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 02/22/2019] [Indexed: 05/20/2023]
Abstract
Photomorphogenesis is an important developmental process that helps the seedlings adapt to external light conditions. B-Box proteins are a family of transcription factors that regulate photomorphogenic responses. BBX31 negatively regulates photomorphogenesis under visible light. In contrast, it promotes photomorphogenesis under UV-B and enhances tolerance to high doses of UV-B radiation. BBX31 and HY5 independently and oppositely regulate the ability of seedlings to adapt to varying light intensities. BBX31 also regulates primary root elongation under low intensities of white light. GC-MS and HPLC-based metabolite profiling identified differential accumulation of multiple primary and secondary metabolites in 35S:BBX31 that might enhance tolerance to UV-B.
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Affiliation(s)
- Arpita Yadav
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, Madhya Pradesh, India
| | - Maneesh Lingwan
- School of Basic Sciences, Indian Institute of Technology (IIT), Mandi, Himachal Pradesh, India
| | - Premachandran Yadukrishnan
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, Madhya Pradesh, India
| | - Shyam Kumar Masakapalli
- School of Basic Sciences, Indian Institute of Technology (IIT), Mandi, Himachal Pradesh, India
- Shyam Kumar Masakapalli Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Sourav Datta
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, Madhya Pradesh, India
- CONTACT Sourav Datta
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Intracellular Fate of Universally Labelled 13C Isotopic Tracers of Glucose and Xylose in Central Metabolic Pathways of Xanthomonas oryzae. Metabolites 2018; 8:metabo8040066. [PMID: 30326608 PMCID: PMC6316632 DOI: 10.3390/metabo8040066] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/26/2018] [Accepted: 10/11/2018] [Indexed: 11/16/2022] Open
Abstract
The goal of this study is to map the metabolic pathways of poorly understood bacterial phytopathogen, Xanthomonas oryzae (Xoo) BXO43 fed with plant mimicking media XOM2 containing glutamate, methionine and either 40% [13C₅] xylose or 40% [13C₆] glucose. The metabolic networks mapped using the KEGG mapper and the mass isotopomer fragments of proteinogenic amino acids derived from GC-MS provided insights into the activities of Xoo central metabolic pathways. The average 13C in histidine, aspartate and other amino acids confirmed the activities of PPP, the TCA cycle and amino acid biosynthetic routes, respectively. The similar labelling patterns of amino acids (His, Ala, Ser, Val and Gly) from glucose and xylose feeding experiments suggests that PPP would be the main metabolic route in Xoo. Owing to the lack of annotated gene phosphoglucoisomerase in BXO43, the 13C incorporation in alanine could not be attributed to the competing pathways and hence warrants additional positional labelling experiments. The negligible presence of 13C incorporation in methionine brings into question its potential role in metabolism and pathogenicity. The extent of the average 13C labelling in several amino acids highlighted the contribution of pre-existing pools that need to be accounted for in 13C-flux analysis studies. This study provided the first qualitative insights into central carbon metabolic pathway activities in Xoo.
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Gutiérrez-Luna FM, Hernández-Domínguez EE, Valencia-Turcotte LG, Rodríguez-Sotres R. Review: "Pyrophosphate and pyrophosphatases in plants, their involvement in stress responses and their possible relationship to secondary metabolism". PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 267:11-19. [PMID: 29362089 DOI: 10.1016/j.plantsci.2017.10.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 10/19/2017] [Accepted: 10/26/2017] [Indexed: 05/14/2023]
Abstract
Pyrophosphate (PPi) is produced as byproduct of biosynthesis in the cytoplasm, nucleus, mitochondria and chloroplast, or in the tonoplast and Golgi by membrane-bound H+-pumping pyrophosphatases (PPv). Inorganic pyrophosphatases (E.C. 3.6.1.1; GO:0004427) impulse various biosynthetic reactions by recycling PPi and are essential to living cells. Soluble and membrane-bound enzymes of high specificity have evolved in different protein families and multiple pyrophosphatases are encoded in all plant genomes known to date. The soluble proteins are present in cytoplasm, extracellular space, inside chloroplasts, and perhaps inside mitochondria, nucleus or vacuoles. The cytoplasmic isoforms may compete for PPi with the PPv enzymes and how PPv and soluble activities are controlled is currently unknown, yet the cytoplasmic PPi concentration is high and fairly constant. Manipulation of the PPi metabolism impacts primary metabolism and vice versa, indicating a tight link between PPi levels and carbohydrate metabolism. These enzymes appear to play a role in germination, development and stress adaptive responses. In addition, the transgenic overexpression of PPv has been used to enhance plant tolerance to abiotic stress, but the reasons behind this tolerance are not completely understood. Finally, the relationship of PPi to stress suggest a currently unexplored link between PPi and secondary metabolism.
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Affiliation(s)
- Francisca Morayna Gutiérrez-Luna
- FACULTAD DE QUÍMICA, UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO, Ave. Universidad 3000, Cd. Universitaria, Del. Coyoacán, P.C. 04510, Mexico City, Mexico.
| | | | - Lilián Gabriela Valencia-Turcotte
- FACULTAD DE QUÍMICA, UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO, Ave. Universidad 3000, Cd. Universitaria, Del. Coyoacán, P.C. 04510, Mexico City, Mexico.
| | - Rogelio Rodríguez-Sotres
- FACULTAD DE QUÍMICA, UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO, Ave. Universidad 3000, Cd. Universitaria, Del. Coyoacán, P.C. 04510, Mexico City, Mexico.
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24
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Zhang X, Misra A, Nargund S, Coleman GD, Sriram G. Concurrent isotope-assisted metabolic flux analysis and transcriptome profiling reveal responses of poplar cells to altered nitrogen and carbon supply. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:472-488. [PMID: 29193384 DOI: 10.1111/tpj.13792] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 11/15/2017] [Accepted: 11/23/2017] [Indexed: 05/20/2023]
Abstract
Reduced nitrogen is indispensable to plants. However, its limited availability in soil combined with the energetic and environmental impacts of nitrogen fertilizers motivates research into molecular mechanisms toward improving plant nitrogen use efficiency (NUE). We performed a systems-level investigation of this problem by employing multiple 'omics methodologies on cell suspensions of hybrid poplar (Populus tremula × Populus alba). Acclimation and growth of the cell suspensions in four nutrient regimes ranging from abundant to deficient supplies of carbon and nitrogen revealed that cell growth under low-nitrogen levels was associated with substantially higher NUE. To investigate the underlying metabolic and molecular mechanisms, we concurrently performed steady-state 13 C metabolic flux analysis with multiple isotope labels and transcriptomic profiling with cDNA microarrays. The 13 C flux analysis revealed that the absolute flux through the oxidative pentose phosphate pathway (oxPPP) was substantially lower (~threefold) under low-nitrogen conditions. Additionally, the flux partitioning ratio between the tricarboxylic acid cycle and anaplerotic pathways varied from 84%:16% under abundant carbon and nitrogen to 55%:45% under deficient carbon and nitrogen. Gene expression data, together with the flux results, suggested a plastidic localization of the oxPPP as well as transcriptional regulation of certain metabolic branchpoints, including those between glycolysis and the oxPPP. The transcriptome data also indicated that NUE-improving mechanisms may involve a redirection of excess carbon to aromatic metabolic pathways and extensive downregulation of potentially redundant genes (in these heterotrophic cells) that encode photosynthetic and light-harvesting proteins, suggesting the recruitment of these proteins as nitrogen sinks in nitrogen-abundant conditions.
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Affiliation(s)
- Xiaofeng Zhang
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Ashish Misra
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Shilpa Nargund
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Gary D Coleman
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, 20742, USA
| | - Ganesh Sriram
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, 20742, USA
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25
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Lima VF, de Souza LP, Williams TCR, Fernie AR, Daloso DM. Gas Chromatography-Mass Spectrometry-Based 13C-Labeling Studies in Plant Metabolomics. Methods Mol Biol 2018; 1778:47-58. [PMID: 29761430 DOI: 10.1007/978-1-4939-7819-9_4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Stable-isotope labeling analysis has been used to discover new metabolic pathways and their key regulatory points in a wide range of organisms. Given the complexity of the plant metabolic network, this analysis provides information complementary to that obtained from metabolite profiling that can be used to understand how plants cope with adverse conditions, and how metabolism varies between different cells, tissues, and organs. Here we describe the experimental procedures from sample harvesting and extraction to mass spectral analysis and interpretation that allow the researcher to perform 13C-labeling experiments. A wide range of plant material, from single cells to whole plants, can be used to investigate the metabolic fate of the 13C from a predefined tracer. Thus, a key point of this analysis is to choose the correct biological system, the substrate and the condition to be investigated; all of which implicitly relies on the biological question to be investigated. Rapid sample quenching and a careful data analysis are also critical points in such studies. By contrast to other metabolomic approaches, stable-isotope labeling can provide information concerning the fluxes through metabolic networks, which is essential for understanding and manipulating metabolic phenotypes and therefore of pivotal importance for both systems biology and plant metabolic engineering.
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Affiliation(s)
- Valéria F Lima
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, CE, Brazil
| | | | | | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Danilo M Daloso
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, CE, Brazil.
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26
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Cavalcanti JHF, Quinhones CGS, Schertl P, Brito DS, Eubel H, Hildebrandt T, Nunes-Nesi A, Braun HP, Araújo WL. Differential impact of amino acids on OXPHOS system activity following carbohydrate starvation in Arabidopsis cell suspensions. PHYSIOLOGIA PLANTARUM 2017; 161:451-467. [PMID: 28767134 DOI: 10.1111/ppl.12612] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/20/2017] [Accepted: 07/25/2017] [Indexed: 06/07/2023]
Abstract
Plant respiration mostly depends on the activity of glycolysis and the oxidation of organic acids in the tricarboxylic acid cycle to synthesize ATP. However, during stress situations plant cells also use amino acids as alternative substrates to donate electrons through the electron-transfer flavoprotein (ETF)/ETF:ubiquinone oxidoreductase (ETF/ETFQO) complex to the mitochondrial electron transport chain (mETC). Given this, we investigated changes of the oxidative phosphorylation (OXPHOS) system in Arabidopsis thaliana cell culture under carbohydrate starvation supplied with a range of amino acids. Induction of isovaleryl-CoA dehydrogenase (IVDH) activity was observed under carbohydrate starvation which was associated with increased amounts of IVDH protein detected by immunoblotting. Furthermore, activities of the protein complexes of the mETC were reduced under carbohydrate starvation. We also observed that OXPHOS system activity behavior is differently affected by different amino acids and that proteins associated with amino acids catabolism are upregulated in cells following carbohydrate starvation. Collectively, our results support the contention that ETF/ETFQO is an essential pathway to donate electrons to the mETC and that amino acids are alternative substrates to maintain respiration under carbohydrate starvation.
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Affiliation(s)
- João Henrique F Cavalcanti
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil
- Institut für Pflanzengenetik, Leibniz Universität Hannover, 30419, Hannover, Germany
| | - Carla G S Quinhones
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil
- Institut für Pflanzengenetik, Leibniz Universität Hannover, 30419, Hannover, Germany
| | - Peter Schertl
- Institut für Pflanzengenetik, Leibniz Universität Hannover, 30419, Hannover, Germany
| | - Danielle S Brito
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil
- Institut für Pflanzengenetik, Leibniz Universität Hannover, 30419, Hannover, Germany
| | - Holger Eubel
- Institut für Pflanzengenetik, Leibniz Universität Hannover, 30419, Hannover, Germany
| | - Tatjana Hildebrandt
- Institut für Pflanzengenetik, Leibniz Universität Hannover, 30419, Hannover, Germany
| | - Adriano Nunes-Nesi
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil
| | - Hans-Peter Braun
- Institut für Pflanzengenetik, Leibniz Universität Hannover, 30419, Hannover, Germany
| | - Wagner L Araújo
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil
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27
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Cell-Type Specific Metabolic Flux Analysis: A Challenge for Metabolic Phenotyping and a Potential Solution in Plants. Metabolites 2017; 7:metabo7040059. [PMID: 29137184 PMCID: PMC5746739 DOI: 10.3390/metabo7040059] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 12/22/2022] Open
Abstract
Stable isotope labelling experiments are used routinely in metabolic flux analysis (MFA) to determine the metabolic phenotype of cells and tissues. A complication arises in multicellular systems because single cell measurements of transcriptomes, proteomes and metabolomes in multicellular organisms suggest that the metabolic phenotype will differ between cell types. In silico analysis of simulated metabolite isotopomer datasets shows that cellular heterogeneity confounds conventional MFA because labelling data averaged over multiple cell types does not necessarily yield averaged flux values. A potential solution to this problem—the use of cell-type specific reporter proteins as a source of cell-type specific labelling data—is proposed and the practicality of implementing this strategy in the roots of Arabidopsis thaliana seedlings is explored. A protocol for the immunopurification of ectopically expressed green fluorescent protein (GFP) from Arabidopsis thaliana seedlings using a GFP-binding nanobody is developed, and through GC-MS analysis of protein hydrolysates it is established that constitutively expressed GFP reports accurately on the labelling of total protein in root tissues. It is also demonstrated that the constitutive expression of GFP does not perturb metabolism. The principal obstacle to the implementation of the method in tissues with cell-type specific GFP expression is the sensitivity of the GC-MS system.
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28
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Hendry JI, Prasannan C, Ma F, Möllers KB, Jaiswal D, Digmurti M, Allen DK, Frigaard NU, Dasgupta S, Wangikar PP. Rerouting of carbon flux in a glycogen mutant of cyanobacteria assessed via isotopically non-stationary 13 C metabolic flux analysis. Biotechnol Bioeng 2017; 114:2298-2308. [PMID: 28600876 DOI: 10.1002/bit.26350] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/09/2017] [Accepted: 06/09/2017] [Indexed: 01/14/2023]
Abstract
Cyanobacteria, which constitute a quantitatively dominant phylum, have attracted attention in biofuel applications due to favorable physiological characteristics, high photosynthetic efficiency and amenability to genetic manipulations. However, quantitative aspects of cyanobacterial metabolism have received limited attention. In the present study, we have performed isotopically non-stationary 13 C metabolic flux analysis (INST-13 C-MFA) to analyze rerouting of carbon in a glycogen synthase deficient mutant strain (glgA-I glgA-II) of the model cyanobacterium Synechococcus sp. PCC 7002. During balanced photoautotrophic growth, 10-20% of the fixed carbon is stored in the form of glycogen via a pathway that is conserved across the cyanobacterial phylum. Our results show that deletion of glycogen synthase gene orchestrates cascading effects on carbon distribution in various parts of the metabolic network. Carbon that was originally destined to be incorporated into glycogen gets partially diverted toward alternate storage molecules such as glucosylglycerol and sucrose. The rest is partitioned within the metabolic network, primarily via glycolysis and tricarboxylic acid cycle. A lowered flux toward carbohydrate synthesis and an altered distribution at the glucose-1-phosphate node indicate flexibility in the network. Further, reversibility of glycogen biosynthesis reactions points toward the presence of futile cycles. Similar redistribution of carbon was also predicted by Flux Balance Analysis. The results are significant to metabolic engineering efforts with cyanobacteria where fixed carbon needs to be re-routed to products of interest. Biotechnol. Bioeng. 2017;114: 2298-2308. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- John I Hendry
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Charulata Prasannan
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,DBT-Pan IIT Center for Bioenergy, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Fangfang Ma
- Donald Danforth Plant Science Center, US Department of Agriculture, St. Louis, Missouri, 63132
| | - K Benedikt Möllers
- Department of Biology, University of Copenhagen, Helsingør, 3000, Denmark
| | - Damini Jaiswal
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Madhuri Digmurti
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Doug K Allen
- Donald Danforth Plant Science Center, US Department of Agriculture, St. Louis, Missouri, 63132.,Agricultural Research Service, US Department of Agriculture, St. Louis, Missouri, 63132
| | | | - Santanu Dasgupta
- Reliance Research and Development Centre, Reliance Corporate Park, Reliance Industries Ltd., Thane-Belapur Road, Ghansoli, Navi Mumbai, 400 701, India
| | - Pramod P Wangikar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,DBT-Pan IIT Center for Bioenergy, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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29
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Maralingannavar V, Parmar D, Pant T, Gadgil C, Panchagnula V, Gadgil M. CHO Cells adapted to inorganic phosphate limitation show higher growth and higher pyruvate carboxylase flux in phosphate replete conditions. Biotechnol Prog 2017; 33:749-758. [PMID: 28220676 DOI: 10.1002/btpr.2450] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/02/2017] [Indexed: 11/07/2022]
Abstract
Inorganic phosphate (Pi ) is an essential ion involved in diverse cellular processes including metabolism. Changes in cellular metabolism upon long term adaptation to Pi limitation have been reported in E. coli. Given the essential role of Pi , adaptation to Pi limitation may also result in metabolic changes in animal cells. In this study, we have adapted CHO cells producing recombinant IgG to limiting Pi conditions for 75 days. Not surprisingly, adapted cells showed better survival under Pi limitation. Here, we report the finding that such cells also showed better growth characteristics compared to control in batch culture replete with Pi (higher peak density and integral viable cell density), accompanied by a lower specific oxygen uptake rate and cytochrome oxidase activity towards the end of exponential phase. Surprisingly, the adapted cells grew to a lower peak density under glucose limitation. This suggests long term Pi limitation may lead to selection for an altered metabolism with higher dependence on glucose availability for biomass assimilation compared to control. Steady state U-13 C glucose labeling experiments suggest that adapted cells have a higher pyruvate carboxylase flux. Consistent with this observation, supplementation with aspartate abolished the peak density difference whereas supplementation with serine did not abolish the difference. This supports the hypothesis that cell growth in the adapted culture might be higher due to a higher pyruvate carboxylase flux. Decreased fitness under carbon limitation and mutations in the sucABCD operon has been previously reported in E. coli upon long term adaptation to Pi limitation, suggestive of a similarity in cellular response among such diverse species. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:749-758, 2017.
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Affiliation(s)
- Vishwanathgouda Maralingannavar
- Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.,CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune
| | - Dharmeshkumar Parmar
- Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.,CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune
| | - Tejal Pant
- Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India
| | - Chetan Gadgil
- Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.,CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune
| | - Venkateswarlu Panchagnula
- Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.,CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune
| | - Mugdha Gadgil
- Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.,CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune
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30
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Shane MW, Feil R, Lunn JE, Plaxton WC. Light-dependent activation of phosphoenolpyruvate carboxylase by reversible phosphorylation in cluster roots of white lupin plants: diurnal control in response to photosynthate supply. ANNALS OF BOTANY 2016; 118:637-643. [PMID: 27063365 PMCID: PMC5055616 DOI: 10.1093/aob/mcw040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/18/2015] [Accepted: 01/22/2016] [Indexed: 05/03/2023]
Abstract
Background and Aims Phosphoenolpyruvate carboxylase (PEPC) is a tightly regulated enzyme that controls carbohydrate partitioning to organic acid anions (malate, citrate) excreted in copious amounts by cluster roots of inorganic phosphate (Pi)-deprived white lupin plants. Excreted malate and citrate solubilize otherwise inaccessible sources of mineralized soil Pi for plant uptake. The aim of this study was to test the hypotheses that (1) PEPC is post-translationally activated by reversible phosphorylation in cluster roots of illuminated white lupin plants, and (2) light-dependent phosphorylation of cluster root PEPC is associated with elevated intracellular levels of sucrose and its signalling metabolite, trehalose-6-phosphate. Methods White lupin plants were cultivated hydroponically at low Pi levels (≤1 µm) and subjected to various light/dark pretreatments. Cluster root PEPC activity and in vivo phosphorylation status were analysed to assess the enzyme's diurnal, post-translational control in response to light and dark. Levels of various metabolites, including sucrose and trehalose-6-phosphate, were also quantified in cluster root extracts using enzymatic and spectrometric methods. Key Results During the daytime the cluster root PEPC was activated by phosphorylation at its conserved N-terminal seryl residue. Darkness triggered a progressive reduction in PEPC phosphorylation to undetectable levels, and this was correlated with 75-80 % decreases in concentrations of sucrose and trehalose-6- phosphate. Conclusions Reversible, light-dependent regulatory PEPC phosphorylation occurs in cluster roots of Pi-deprived white lupin plants. This likely facilitates the well-documented light- and sucrose-dependent exudation of Pi-solubilizing organic acid anions by the cluster roots. PEPC's in vivo phosphorylation status appears to be modulated by sucrose translocated from CO2-fixing leaves into the non-photosynthetic cluster roots.
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Affiliation(s)
- Michael W. Shane
- School of Plant Biology (M084), Faculty of Natural and Agricultural Sciences, The University of Western Australia, Crawley 6009, Australia
- Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, and College of Forestry, Guangxi University, Daxuedonglu 100, Nanning 530004, Guangxi, China
| | - Regina Feil
- Department of Metabolic Networks, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - John E. Lunn
- Department of Metabolic Networks, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - William C. Plaxton
- Department of Biology, Queen’s University, Kingston, Ontario K7L 3N6, Canada
- Department of Biomedical and Molecular Biosciences Queen’s University, Kingston, Ontario K7L 3N6, Canada
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31
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Esteban R, Ariz I, Cruz C, Moran JF. Review: Mechanisms of ammonium toxicity and the quest for tolerance. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 248:92-101. [PMID: 27181951 DOI: 10.1016/j.plantsci.2016.04.008] [Citation(s) in RCA: 186] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 04/14/2016] [Accepted: 04/16/2016] [Indexed: 05/21/2023]
Abstract
Ammonium sensitivity of plants is a worldwide problem, constraining crop production. Prolonged application of ammonium as the sole nitrogen source may result in physiological and morphological disorders that lead to decreased plant growth and toxicity. The main causes of ammonium toxicity/tolerance described until now include high ammonium assimilation by plants and/or low sensitivity to external pH acidification. The various ammonium transport-related components, especially the non-electrogenic influx of NH3 (related to the depletion of (15)N) and the electrogenic influx of NH4(+), may contribute to ammonium accumulation, and therefore to NH3 toxicity. However, this accumulation may be influenced by increasing K(+) concentration in the root medium. Recently, new insights have been provided by "omics" studies, leading to a suggested involvement of GDP mannose-pyrophosphorylase in the response pathways of NH4(+) stress. In this review, we highlight the cross-talk signaling between nitrate, auxins and NO, and the importance of the connection of the plants' urea cycle to metabolism of polyamines. Overall, the tolerance and amelioration of ammonium toxicity are outlined to improve the yield of ammonium-grown plants. This review identifies future directions of research, focusing on the putative importance of aquaporins in ammonium influx, and on genes involved in ammonium sensitivity and tolerance.
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Affiliation(s)
- Raquel Esteban
- Institute of Agrobiotechnology, IdAB-CSIC-UPNA-Government of Navarre, Avda. de Pamplona 123, E-31192 Mutilva, Navarre, Spain
| | - Idoia Ariz
- Faculdade de Ciências, Centro Ecologia Evolução e Alterações Ambientais, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Cristina Cruz
- Faculdade de Ciências, Centro Ecologia Evolução e Alterações Ambientais, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Jose Fernando Moran
- Institute of Agrobiotechnology, IdAB-CSIC-UPNA-Government of Navarre, Avda. de Pamplona 123, E-31192 Mutilva, Navarre, Spain.
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32
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Hodges M, Dellero Y, Keech O, Betti M, Raghavendra AS, Sage R, Zhu XG, Allen DK, Weber APM. Perspectives for a better understanding of the metabolic integration of photorespiration within a complex plant primary metabolism network. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3015-26. [PMID: 27053720 DOI: 10.1093/jxb/erw145] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Photorespiration is an essential high flux metabolic pathway that is found in all oxygen-producing photosynthetic organisms. It is often viewed as a closed metabolic repair pathway that serves to detoxify 2-phosphoglycolic acid and to recycle carbon to fuel the Calvin-Benson cycle. However, this view is too simplistic since the photorespiratory cycle is known to interact with several primary metabolic pathways, including photosynthesis, nitrate assimilation, amino acid metabolism, C1 metabolism and the Krebs (TCA) cycle. Here we will review recent advances in photorespiration research and discuss future priorities to better understand (i) the metabolic integration of the photorespiratory cycle within the complex network of plant primary metabolism and (ii) the importance of photorespiration in response to abiotic and biotic stresses.
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Affiliation(s)
- Michael Hodges
- Institute of Plant Sciences Paris-Saclay, Université Paris-Sud, CNRS, INRA, Université d'Evry, 91405 Orsay Cedex, France
| | - Younès Dellero
- Institute of Plant Sciences Paris-Saclay, Université Paris-Sud, CNRS, INRA, Université d'Evry, 91405 Orsay Cedex, France
| | - Olivier Keech
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, SE-90187 Umeå, Sweden
| | - Marco Betti
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, Universidad de Sevilla, 141012 Sevilla, Spain
| | - Agepati S Raghavendra
- School of Life Sciences, Department of Plant Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Rowan Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S3B2, Canada
| | - Xin-Guang Zhu
- CAS-MPG Partner Institutes for Computational Biology, Shanghai Institutes for Biological Sciences, CAS, Shanghai 200031, China
| | - Doug K Allen
- United States Department of Agriculture-Agricultural Research Service, Plant Genetics Research Unit, Donald Danforth Plant Science Center, St Louis, MO 63132, USA
| | - Andreas P M Weber
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Science (CEPLAS), Heinrich-Heine-Universität, Universitätsstraße 1, and Cluster of Excellence on Plant Sciences, 40225 Düsseldorf, Germany
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33
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Allen DK. Assessing compartmentalized flux in lipid metabolism with isotopes. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1226-1242. [PMID: 27003250 DOI: 10.1016/j.bbalip.2016.03.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 03/13/2016] [Accepted: 03/14/2016] [Indexed: 12/28/2022]
Abstract
Metabolism in plants takes place across multiple cell types and within distinct organelles. The distributions equate to spatial heterogeneity; though the limited means to experimentally assess metabolism frequently involve homogenizing tissues and mixing metabolites from different locations. Most current isotope investigations of metabolism therefore lack the ability to resolve spatially distinct events. Recognition of this limitation has resulted in inspired efforts to advance metabolic flux analysis and isotopic labeling techniques. Though a number of these efforts have been applied to studies in central metabolism; recent advances in instrumentation and techniques present an untapped opportunity to make similar progress in lipid metabolism where the use of stable isotopes has been more limited. These efforts will benefit from sophisticated radiolabeling reports that continue to enrich our knowledge on lipid biosynthetic pathways and provide some direction for stable isotope experimental design and extension of MFA. Evidence for this assertion is presented through the review of several elegant stable isotope studies and by taking stock of what has been learned from radioisotope investigations when spatial aspects of metabolism were considered. The studies emphasize that glycerolipid production occurs across several locations with assembly of lipids in the ER or plastid, fatty acid biosynthesis occurring in the plastid, and the generation of acetyl-CoA and glycerol-3-phosphate taking place at multiple sites. Considering metabolism in this context underscores the cellular and subcellular organization that is important to enhanced production of glycerolipids in plants. An attempt is made to unify salient features from a number of reports into a diagrammatic model of lipid metabolism and propose where stable isotope labeling experiments and further flux analysis may help address questions in the field. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Doug K Allen
- United States Department of Agriculture, Agricultural Research Service, 975 North Warson Road, St. Louis, MO 63132, United States; Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, United States.
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Dersch LM, Beckers V, Wittmann C. Green pathways: Metabolic network analysis of plant systems. Metab Eng 2016; 34:1-24. [DOI: 10.1016/j.ymben.2015.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/30/2015] [Accepted: 12/01/2015] [Indexed: 12/18/2022]
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Allen DK. Quantifying plant phenotypes with isotopic labeling & metabolic flux analysis. Curr Opin Biotechnol 2015; 37:45-52. [PMID: 26613198 DOI: 10.1016/j.copbio.2015.10.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/04/2015] [Accepted: 10/06/2015] [Indexed: 12/14/2022]
Abstract
Analyses of metabolic flux using stable isotopes in plants have traditionally been restricted to tissues with presumed homogeneous cell populations and long metabolic steady states such as developing seeds, cell suspensions, or cultured roots and root tips. It is now possible to describe these and other metabolically more dynamic tissues such as leaves in greater detail using novel methods in mass spectrometry, isotope labeling strategies, and transient labeling-based flux analyses. Such studies are necessary for a systems level description of plant function that more closely represents biological reality, and provides insights into the genes that will need to be modified as natural resources become ever more limited and environments change.
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Affiliation(s)
- Doug K Allen
- United States Department of Agriculture-Agricultural Research Service, Plant Genetics Research Unit, 975 North Warson Road, St. Louis, MO 63132, United States; Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, United States.
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36
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Royo B, Moran JF, Ratcliffe RG, Gupta KJ. Nitric oxide induces the alternative oxidase pathway in Arabidopsis seedlings deprived of inorganic phosphate. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:6273-80. [PMID: 26163703 PMCID: PMC4588884 DOI: 10.1093/jxb/erv338] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Phosphate starvation compromises electron flow through the cytochrome pathway of the mitochondrial electron transport chain, and plants commonly respond to phosphate deprivation by increasing flow through the alternative oxidase (AOX). To test whether this response is linked to the increase in nitric oxide (NO) production that also increases under phosphate starvation, Arabidopsis thaliana seedlings were grown for 15 d on media containing either 0 or 1mM inorganic phosphate. The effects of the phosphate supply on growth, the production of NO, respiration, the AOX level and the production of superoxide were compared for wild-type (WT) seedlings and the nitrate reductase double mutant nia. Phosphate deprivation increased NO production in WT roots, and the AOX level and the capacity of the alternative pathway to consume electrons in WT seedlings; whereas the same treatment failed to stimulate NO production and AOX expression in the nia mutant, and the plants had an altered growth phenotype. The NO donor S-nitrosoglutathione rescued the growth phenotype of the nia mutants under phosphate deprivation to some extent, and it also increased the respiratory capacity of AOX. It is concluded that NO is required for the induction of the AOX pathway when seedlings are grown under phosphate-limiting conditions.
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Affiliation(s)
- Beatriz Royo
- Department of Plant Sciences, University of Oxford, South Park Road, Oxford OX1 3RB, UK Institute of Agrobiotechnology, IdAB-CSIC-Public University of Navarre-Government of Navarre, Avda. Pamplona 123, E-31192, Mutilva, Navarre, Spain
| | - Jose F Moran
- Institute of Agrobiotechnology, IdAB-CSIC-Public University of Navarre-Government of Navarre, Avda. Pamplona 123, E-31192, Mutilva, Navarre, Spain
| | - R George Ratcliffe
- Department of Plant Sciences, University of Oxford, South Park Road, Oxford OX1 3RB, UK
| | - Kapuganti J Gupta
- Department of Plant Sciences, University of Oxford, South Park Road, Oxford OX1 3RB, UK National Institute of Plant Genome Research, Aruna Asaf Ali Marg, Jawaharlal Nehru University, New Delhi, Delhi 110067, India
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Zhang T, Zhang A, Qiu S, Yang S, Wang X. Current Trends and Innovations in Bioanalytical Techniques of Metabolomics. Crit Rev Anal Chem 2015; 46:342-51. [DOI: 10.1080/10408347.2015.1079475] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Hernández I, Munné-Bosch S. Linking phosphorus availability with photo-oxidative stress in plants. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2889-900. [PMID: 25740928 DOI: 10.1093/jxb/erv056] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plants have evolved a plethora of mechanisms to circumvent the potential damaging effects of living under low phosphorus availability in the soil. These mechanisms include different levels of organization, from root-shoot signalling at the whole-plant level to specific biochemical responses at the subcellular level, such as reductions in photosynthesis and the consequent activation of photo- and antioxidant mechanisms in chloroplasts. Some recent studies clearly indicate that severe phosphorus deficiency can lead to alterations in the photosynthetic apparatus, including reductions in CO2 assimilation rates, a down-regulation of photosynthesis-related genes and photoinhibition at the photosystem II level, thus causing potential photo-oxidative stress. Photo-oxidative stress is characterized by an increased production of reactive oxygen species in chloroplasts, which at low concentrations can serve a signalling, protective role, but when present at high concentrations can cause damage to lipids, proteins and nucleic acids, thus leading to irreversible injuries. We discuss here the mechanisms that phosphate-starved plants have evolved to withstand photo-oxidative stress, including changes at the subcellular level (e.g. activation of photo- and antioxidant protection mechanisms in chloroplasts), cellular and tissular levels (e.g. activation of photorespiration and anthocyanin accumulation) and whole-plant level (alterations in source-sink relationships modulated by hormones). Of particular importance is the current evidence demonstrating that phosphate-starved plants activate simultaneous responses at multiple levels, from transcriptional changes to root-shoot signalling, to prevent oxidative damage. In this review, we summarize current knowledge about the occurrence of photo-oxidative stress in phosphate-starved plants and highlight the mechanisms these plants have evolved to prevent oxidative damage under phosphorus limitation at the subcellular, cellular and whole-plant levels.
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Affiliation(s)
- Iker Hernández
- Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, E-08028 Barcelona, Spain
| | - Sergi Munné-Bosch
- Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, E-08028 Barcelona, Spain
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Fluxes through plant metabolic networks: measurements, predictions, insights and challenges. Biochem J 2015; 465:27-38. [PMID: 25631681 DOI: 10.1042/bj20140984] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although the flows of material through metabolic networks are central to cell function, they are not easy to measure other than at the level of inputs and outputs. This is particularly true in plant cells, where the network spans multiple subcellular compartments and where the network may function either heterotrophically or photoautotrophically. For many years, kinetic modelling of pathways provided the only method for describing the operation of fragments of the network. However, more recently, it has become possible to map the fluxes in central carbon metabolism using the stable isotope labelling techniques of metabolic flux analysis (MFA), and to predict intracellular fluxes using constraints-based modelling procedures such as flux balance analysis (FBA). These approaches were originally developed for the analysis of microbial metabolism, but over the last decade, they have been adapted for the more demanding analysis of plant metabolic networks. Here, the principal features of MFA and FBA as applied to plants are outlined, followed by a discussion of the insights that have been gained into plant metabolic networks through the application of these time-consuming and non-trivial methods. The discussion focuses on how a system-wide view of plant metabolism has increased our understanding of network structure, metabolic perturbations and the provision of reducing power and energy for cell function. Current methodological challenges that limit the scope of plant MFA are discussed and particular emphasis is placed on the importance of developing methods for cell-specific MFA.
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Allen DK, Bates PD, Tjellström H. Tracking the metabolic pulse of plant lipid production with isotopic labeling and flux analyses: Past, present and future. Prog Lipid Res 2015; 58:97-120. [PMID: 25773881 DOI: 10.1016/j.plipres.2015.02.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 01/30/2015] [Accepted: 02/11/2015] [Indexed: 11/25/2022]
Abstract
Metabolism is comprised of networks of chemical transformations, organized into integrated biochemical pathways that are the basis of cellular operation, and function to sustain life. Metabolism, and thus life, is not static. The rate of metabolites transitioning through biochemical pathways (i.e., flux) determines cellular phenotypes, and is constantly changing in response to genetic or environmental perturbations. Each change evokes a response in metabolic pathway flow, and the quantification of fluxes under varied conditions helps to elucidate major and minor routes, and regulatory aspects of metabolism. To measure fluxes requires experimental methods that assess the movements and transformations of metabolites without creating artifacts. Isotopic labeling fills this role and is a long-standing experimental approach to identify pathways and quantify their metabolic relevance in different tissues or under different conditions. The application of labeling techniques to plant science is however far from reaching it potential. In light of advances in genetics and molecular biology that provide a means to alter metabolism, and given recent improvements in instrumentation, computational tools and available isotopes, the use of isotopic labeling to probe metabolism is becoming more and more powerful. We review the principal analytical methods for isotopic labeling with a focus on seminal studies of pathways and fluxes in lipid metabolism and carbon partitioning through central metabolism. Central carbon metabolic steps are directly linked to lipid production by serving to generate the precursors for fatty acid biosynthesis and lipid assembly. Additionally some of the ideas for labeling techniques that may be most applicable for lipid metabolism in the future were originally developed to investigate other aspects of central metabolism. We conclude by describing recent advances that will play an important future role in quantifying flux and metabolic operation in plant tissues.
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Affiliation(s)
- Doug K Allen
- United States Department of Agriculture, Agricultural Research Service, 975 North Warson Road, St. Louis, MO 63132, United States; Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, United States.
| | - Philip D Bates
- Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, MS 39406, United States
| | - Henrik Tjellström
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, United States; Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824, United States
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Schwender J, König C, Klapperstück M, Heinzel N, Munz E, Hebbelmann I, Hay JO, Denolf P, De Bodt S, Redestig H, Caestecker E, Jakob PM, Borisjuk L, Rolletschek H. Transcript abundance on its own cannot be used to infer fluxes in central metabolism. FRONTIERS IN PLANT SCIENCE 2014; 5:668. [PMID: 25506350 PMCID: PMC4246676 DOI: 10.3389/fpls.2014.00668] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 11/10/2014] [Indexed: 05/18/2023]
Abstract
An attempt has been made to define the extent to which metabolic flux in central plant metabolism is reflected by changes in the transcriptome and metabolome, based on an analysis of in vitro cultured immature embryos of two oilseed rape (Brassica napus) accessions which contrast for seed lipid accumulation. Metabolic flux analysis (MFA) was used to constrain a flux balance metabolic model which included 671 biochemical and transport reactions within the central metabolism. This highly confident flux information was eventually used for comparative analysis of flux vs. transcript (metabolite). Metabolite profiling succeeded in identifying 79 intermediates within the central metabolism, some of which differed quantitatively between the two accessions and displayed a significant shift corresponding to flux. An RNA-Seq based transcriptome analysis revealed a large number of genes which were differentially transcribed in the two accessions, including some enzymes/proteins active in major metabolic pathways. With a few exceptions, differential activity in the major pathways (glycolysis, TCA cycle, amino acid, and fatty acid synthesis) was not reflected in contrasting abundances of the relevant transcripts. The conclusion was that transcript abundance on its own cannot be used to infer metabolic activity/fluxes in central plant metabolism. This limitation needs to be borne in mind in evaluating transcriptome data and designing metabolic engineering experiments.
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Affiliation(s)
- Jörg Schwender
- Brookhaven National Laboratory, Department of Biological, Environmental and Climate SciencesUpton, NY, USA
| | - Christina König
- Leibniz-Institut für Pflanzengenetik und KulturpflanzenforschungGatersleben, Germany
| | - Matthias Klapperstück
- Leibniz-Institut für Pflanzengenetik und KulturpflanzenforschungGatersleben, Germany
| | - Nicolas Heinzel
- Leibniz-Institut für Pflanzengenetik und KulturpflanzenforschungGatersleben, Germany
| | - Eberhard Munz
- Leibniz-Institut für Pflanzengenetik und KulturpflanzenforschungGatersleben, Germany
- University of Würzburg, Institute of Experimental Physics 5Würzburg, Germany
| | - Inga Hebbelmann
- Brookhaven National Laboratory, Department of Biological, Environmental and Climate SciencesUpton, NY, USA
| | - Jordan O. Hay
- Brookhaven National Laboratory, Department of Biological, Environmental and Climate SciencesUpton, NY, USA
| | - Peter Denolf
- Bayer CropScience NV, Trait ResearchZwijnaarde, Belgium
| | | | | | | | - Peter M. Jakob
- University of Würzburg, Institute of Experimental Physics 5Würzburg, Germany
| | - Ljudmilla Borisjuk
- Leibniz-Institut für Pflanzengenetik und KulturpflanzenforschungGatersleben, Germany
| | - Hardy Rolletschek
- Leibniz-Institut für Pflanzengenetik und KulturpflanzenforschungGatersleben, Germany
- *Correspondence: Hardy Rolletschek, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse 3, 06466 Gatersleben, Germany e-mail:
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