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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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Kilburn R, Fedosejevs ET, Mehta D, Soleimani F, Ghahremani M, Monaghan J, Thelen JJ, Uhrig RG, Snedden WA, Plaxton WC. Substrate profiling of the Arabidopsis Ca 2+-dependent protein kinase AtCPK4 and its Ricinus communis ortholog RcCDPK1. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023; 331:111675. [PMID: 36931565 DOI: 10.1016/j.plantsci.2023.111675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 03/10/2023] [Accepted: 03/12/2023] [Indexed: 06/18/2023]
Abstract
AtCPK4 and AtCPK11 are Arabidopsis thaliana Ca2+-dependent protein kinase (CDPK) paralogs that have been reported to positively regulate abscisic acid (ABA) signal transduction by phosphorylating ABA-responsive transcription factor-4 (AtABF4). By contrast, RcCDPK1, their closest Ricinus communis ortholog, participates in the control of anaplerotic carbon flux in developing castor oil seeds by catalyzing inhibitory phosphorylation of bacterial-type phosphoenolpyruvate carboxylase at Ser451. LC-MS/MS revealed that AtCPK4 and RcCDPK1 transphosphorylated several common, conserved residues of AtABF4 and its castor ortholog, TRANSCRIPTION FACTOR RESPONSIBLE FOR ABA REGULATON. Arabidopsis atcpk4/atcpk11 mutants displayed an ABA-insensitive phenotype that corroborated the involvement of AtCPK4/11 in ABA signaling. A kinase-client assay was employed to identify additional AtCPK4/RcCDPK1 targets. Both CDPKs were separately incubated with a library of 2095 peptides representative of Arabidopsis protein phosphosites; five overlapping targets were identified including PLANT INTRACELLULAR RAS-GROUP-RELATED LEUCINE-RICH REPEAT PROTEIN-9 (AtPIRL9) and the E3-ubiquitin ligase ARABIDOPSIS TOXICOS EN LEVADURA 6 (AtATL6). AtPIRL9 and AtATL6 residues phosphorylated by AtCPK4/RcCDPK1 conformed to a CDPK recognition motif that was conserved amongst their respective orthologs. Collectively, this study provides evidence for novel AtCPK4/RcCDPK1 substrates, which may help to expand regulatory networks linked to Ca2+- and ABA-signaling, immune responses, and central carbon metabolism.
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Affiliation(s)
- Ryan Kilburn
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Eric T Fedosejevs
- Department of Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, 1201 Rollins Street, Columbia, MO 65211, USA
| | - Devang Mehta
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2E9
| | - Faranak Soleimani
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Mina Ghahremani
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Jacqueline Monaghan
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Jay J Thelen
- Department of Biochemistry, Christopher S. Bond Life Sciences Center, University of Missouri, 1201 Rollins Street, Columbia, MO 65211, USA
| | - R Glen Uhrig
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2E9
| | - Wayne A Snedden
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - William C Plaxton
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
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Chen S, Peng W, Ansah EO, Xiong F, Wu Y. Encoded C 4 homologue enzymes genes function under abiotic stresses in C3 plant. PLANT SIGNALING & BEHAVIOR 2022; 17:2115634. [PMID: 36102341 PMCID: PMC9481101 DOI: 10.1080/15592324.2022.2115634] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 08/12/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Plant organisms assimilate CO2 through the photosynthetic pathway, which facilitates in the synthesis of sugar for plant development. As environmental elements including water level, CO2 concentration, temperature and soil characteristics change, the plants may recruit series of genes to help adapt the hostile environments and challenges. C4 photosynthesis plants are an excellent example of plant evolutionary adaptation to diverse condition. Compared with C3 photosynthesis plants, C4 photosynthesis plants have altered leaf anatomy and new metabolism for CO2 capture, with multiple related enzymes such as phosphoenolpyruvate carboxylase (PEPCase), pyruvate orthophosphate dikinase (PPDK), NAD(P)-malic enzyme (NAD(P)-ME), NAD(P) - malate dehydrogenase (NAD(P)-MDH) and carbonic anhydrases (CA), identified to participate in the carbon concentrating mechanism (CCM) pathway. Recently, great achievements about C4 CCM-related genes have been made in the dissection of C3 plant development processes involving various stresses. In this review, we describe the functions of C4 CCM-related homologous genes in carbon and nitrogen metabolism in C3 plants. We further summarize C4 CCM-related homologous genes' functions in response to stresses in C3 plants. The understanding of C4 CCM-related genes' function in response to abiotic stress in plant is important to modify the crop plants for climate diversification.
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Affiliation(s)
- Simin Chen
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops/Joint International Research Laboratory of Agriculture & Agri-Product Safety, Yangzhou University, Yangzhou, China
| | - Wangmenghan Peng
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops/Joint International Research Laboratory of Agriculture & Agri-Product Safety, Yangzhou University, Yangzhou, China
| | - Ebenezer Ottopah Ansah
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops/Joint International Research Laboratory of Agriculture & Agri-Product Safety, Yangzhou University, Yangzhou, China
| | - Fei Xiong
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops/Joint International Research Laboratory of Agriculture & Agri-Product Safety, Yangzhou University, Yangzhou, China
| | - Yunfei Wu
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops/Joint International Research Laboratory of Agriculture & Agri-Product Safety, Yangzhou University, Yangzhou, China
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4
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de la Osa C, Pérez‐López J, Feria A, Baena G, Marino D, Coleto I, Pérez‐Montaño F, Gandullo J, Echevarría C, García‐Mauriño S, Monreal JA. Knock-down of phosphoenolpyruvate carboxylase 3 negatively impacts growth, productivity, and responses to salt stress in sorghum (Sorghum bicolor L.). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 111:231-249. [PMID: 35488514 PMCID: PMC9539949 DOI: 10.1111/tpj.15789] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 04/21/2022] [Accepted: 04/25/2022] [Indexed: 06/14/2023]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is a carboxylating enzyme with important roles in plant metabolism. Most studies in C4 plants have focused on photosynthetic PEPC, but less is known about non-photosynthetic PEPC isozymes, especially with respect to their physiological functions. In this work, we analyzed the precise roles of the sorghum (Sorghum bicolor) PPC3 isozyme by the use of knock-down lines with the SbPPC3 gene silenced (Ppc3 lines). Ppc3 plants showed reduced stomatal conductance and plant size, a delay in flowering time, and reduced seed production. In addition, silenced plants accumulated stress indicators such as Asn, citrate, malate, and sucrose in roots and showed higher citrate synthase activity, even in control conditions. Salinity further affected stomatal conductance and yield and had a deeper impact on central metabolism in silenced plants compared to wild type, more notably in roots, with Ppc3 plants showing higher nitrate reductase and NADH-glutamate synthase activity in roots and the accumulation of molecules with a higher N/C ratio. Taken together, our results show that although SbPPC3 is predominantly a root protein, its absence causes deep changes in plant physiology and metabolism in roots and leaves, negatively affecting maximal stomatal opening, growth, productivity, and stress responses in sorghum plants. The consequences of SbPPC3 silencing suggest that this protein, and maybe orthologs in other plants, could be an important target to improve plant growth, productivity, and resistance to salt stress and other stresses where non-photosynthetic PEPCs may be implicated.
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Affiliation(s)
- Clara de la Osa
- Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de SevillaSevillaSpain
| | - Jesús Pérez‐López
- Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de SevillaSevillaSpain
| | - Ana‐Belén Feria
- Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de SevillaSevillaSpain
| | - Guillermo Baena
- Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de SevillaSevillaSpain
| | - Daniel Marino
- Departamento de Biología Vegetal y Ecología, Facultad de Ciencia y TecnologíaUniversidad del País Vasco (UPV/EHU)LeioaSpain
- IkerbasqueBasque Foundation for ScienceBilbaoSpain
| | - Inmaculada Coleto
- Departamento de Biología Vegetal y Ecología, Facultad de Ciencia y TecnologíaUniversidad del País Vasco (UPV/EHU)LeioaSpain
| | | | - Jacinto Gandullo
- Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de SevillaSevillaSpain
| | - Cristina Echevarría
- Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de SevillaSevillaSpain
| | - Sofía García‐Mauriño
- Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de SevillaSevillaSpain
| | - José A. Monreal
- Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de SevillaSevillaSpain
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5
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Kilburn R, Gerdis SA, She YM, Snedden WA, Plaxton WC. Autophosphorylation Inhibits RcCDPK1, a Dual-Specificity Kinase that Phosphorylates Bacterial-Type Phosphoenolpyruvate Carboxylase in Castor Oil Seeds. PLANT & CELL PHYSIOLOGY 2022; 63:683-698. [PMID: 35246690 DOI: 10.1093/pcp/pcac030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/01/2022] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is a tightly regulated enzyme that plays a crucial anaplerotic role in central plant metabolism. Bacterial-type PEPC (BTPC) of developing castor oil seeds (COS) is highly expressed as a catalytic and regulatory subunit of a novel Class-2 PEPC heteromeric complex. Ricinus communis Ca2+-dependent protein kinase-1 (RcCDPK1) catalyzes in vivo inhibitory phosphorylation of COS BTPC at Ser451. Autokinase activity of recombinant RcCDPK1 was detected and 42 autophosphorylated Ser, Thr or Tyr residues were mapped via liquid chromatography-tandem mass spectrometry. Prior autophosphorylation markedly attenuated the ability of RcCDPK1 to transphosphorylate its BTPC substrate at Ser451. However, fully dephosphorylated RcCDPK1 rapidly autophosphorylated during the initial stages of a BTPC transphosphorylation assay. This suggests that Ca2+-dependent binding of dephospho-RcCDPK1 to BTPC may trigger a structural change that leads to rapid autophosphorylation and subsequent substrate transphosphorylation. Tyr30 was identified as an autophosphorylation site via LC-MS/MS and immunoblotting with a phosphosite-specific antibody. Tyr30 occurs at the junction of RcCDPK1's N-terminal variable (NTVD) and catalytic domains and is widely conserved in plant and protist CDPKs. Interestingly, a reduced rate and extent of BTPC transphosphorylation occurred with a RcCDPK1Y30F mutant. Prior research demonstrated that RcCDPK1's NTVD is essential for its Ca2+-dependent autophosphorylation or BTPC transphosphorylation activities but plays no role in target recognition. We propose that Tyr30 autophosphorylation facilitates a Ca2+-dependent interaction between the NTVD and Ca2+-activation domain that primes RcCDPK1 for transphosphorylating BTPC at Ser451. Our results provide insights into links between the post-translational control of COS anaplerosis, Ca2+-dependent signaling and the biological significance of RcCDPK1 autophosphorylation.
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Affiliation(s)
- Ryan Kilburn
- Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Suzanne A Gerdis
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON K1A OC6, Canada
| | - Yi-Min She
- Centre for Biologics Evaluation, Biologic and Radiopharmaceutical Drugs Directorate, Health Canada, Ottawa, ON K1A OK9, Canada
| | - Wayne A Snedden
- Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada
| | - William C Plaxton
- Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada
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6
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Cao J, Cheng G, Wang L, Maimaitijiang T, Lan H. Genome-Wide Identification and Analysis of the Phosphoenolpyruvate Carboxylase Gene Family in Suaeda aralocaspica, an Annual Halophyte With Single-Cellular C 4 Anatomy. FRONTIERS IN PLANT SCIENCE 2021; 12:665279. [PMID: 34527003 PMCID: PMC8435749 DOI: 10.3389/fpls.2021.665279] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) plays pivotal roles in the carbon fixation of photosynthesis and a variety of metabolic and stress pathways. Suaeda aralocaspica belongs to a single-cellular C4 species and carries out a photosynthetic pathway in an unusually elongated chlorenchyma cell, which is expected to have PEPCs with different characteristics. To identify the different isoforms of PEPC genes in S. aralocaspica and comparatively analyze their expression and regulation patterns as well as the biochemical and enzymatic properties in this study, we characterized a bacterial-type PEPC (BTPC; SaPEPC-4) in addition to the two plant-type PEPCs (PTPCs; SaPEPC-1 and SaPEPC-2) using a genome-wide identification. SaPEPC-4 presented a lower expression level in all test combinations with an unknown function; two SaPTPCs showed distinct subcellular localizations and different spatiotemporal expression patterns but positively responded to abiotic stresses. Compared to SaPEPC-2, the expression of SaPEPC-1 specifically in chlorenchyma cell tissues was much more active with the progression of development and under various stresses, particularly sensitive to light, implying the involvement of SaPEPC-1 in a C4 photosynthetic pathway. In contrast, SaPEPC-2 was more like a non-photosynthetic PEPC. The expression trends of two SaPTPCs in response to light, development, and abiotic stresses were also matched with the changes in PEPC activity in vivo (native) or in vitro (recombinant), and the biochemical properties of the two recombinant SaPTPCs were similar in response to various effectors while the catalytic efficiency, substrate affinity, and enzyme activity of SaPEPC-2 were higher than that of SaPEPC-1 in vitro. All the different properties between these two SaPTPCs might be involved in transcriptional (e.g., specific cis-elements), posttranscriptional [e.g., 5'-untranslated region (5'-UTR) secondary structure], or translational (e.g., PEPC phosphorylation/dephosphorylation) regulatory events. The comparative studies on the different isoforms of the PEPC gene family in S. aralocaspica may help to decipher their exact role in C4 photosynthesis, plant growth/development, and stress resistance.
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7
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O'Leary B, Plaxton WC. Multifaceted functions of post-translational enzyme modifications in the control of plant glycolysis. CURRENT OPINION IN PLANT BIOLOGY 2020; 55:28-37. [PMID: 32200227 DOI: 10.1016/j.pbi.2020.01.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/24/2020] [Accepted: 01/31/2020] [Indexed: 06/10/2023]
Abstract
Glycolysis is a central feature of metabolism and its regulation plays important roles during plant developmental and stress responses. Recent advances in proteomics and mass spectrometry have documented extensive and dynamic post-translational modifications (PTMs) of most glycolytic enzymes in diverse plant tissues. Protein PTMs represent fundamental regulatory events that integrate signalling and gene expression with cellular metabolic networks, and can regulate glycolytic enzyme activity, localization, protein:protein interactions, moonlighting functions, and turnover. Serine/threonine phosphorylation and redox PTMs of cysteine thiol groups appear to be the most prevalent forms of reversible covalent modification involved in plant glycolytic control. Additional PTMs including monoubiquitination also have important functions. However, the molecular functions and mechanisms of most glycolytic enzyme PTMs remain unknown, and represent important objectives for future studies.
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Affiliation(s)
- Brendan O'Leary
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009, Australia
| | - William C Plaxton
- Department of Biology, Queen's University, Kingston, Ontario K7L3N6, Canada.
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8
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Yamamoto N, Sugimoto T, Takano T, Sasou A, Morita S, Yano K, Masumura T. The plant-type phospho enolpyruvate carboxylase Gmppc2 is developmentally induced in immature soy seeds at the late maturation stage: a potential protein biomarker for seed chemical composition. Biosci Biotechnol Biochem 2020; 84:552-562. [PMID: 31771419 DOI: 10.1080/09168451.2019.1696179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/18/2019] [Indexed: 12/18/2022]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is a carbon-fixing enzyme with critical roles in seed development. Previously we observed a positive correlation between PEPC activity and protein content in mature seeds among soybean cultivars and varietal differences of PEPC activity in immature seeds, which is concordant with seed protein accumulation. Here, we report a PEPC isoform (Gmppc2) which is preferentially expressed in immature soybean seeds at the late maturation stage. Gmppc2 was co-expressed with enzyme genes involved in starch degradation: α-amylase, hexokinase, and α-glucan phosphorylase. Gmppc2 was developmentally induced in the external seed coats, internal seed coats, hypocotyls, and cotyledons at the late maturation stage. The expression of Gmppc2 protein was negatively regulated by the application of a nitrogen fertilizer, which suppressed nodule formation. These results imply that Gmppc2 is involved in the metabolism of nitrogen originated from nodules into seeds, and Gmppc2 might be applicable as a biomarker of seed protein content.Abbreviations: PEP: phosphoenolpyruvate; PEPC: phosphoenolpyruvate carboxylase; RNA-Seq: RNA sequencing; PCA: principal component analysis; SE: standard error.
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Affiliation(s)
- Naoki Yamamoto
- Laboratory of Genetic Engineering, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
- Laboratory of Bioinformatics, Department of Life Sciences, School of Agriculture, Meiji University, Kanagawa, Japan
| | - Toshio Sugimoto
- Plant Nutrition Laboratory, Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | - Tomoyuki Takano
- Laboratory of Bioinformatics, Department of Life Sciences, School of Agriculture, Meiji University, Kanagawa, Japan
| | - Ai Sasou
- Laboratory of Genetic Engineering, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Shigeto Morita
- Laboratory of Genetic Engineering, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
- Biotechnology Research Department, Kyoto Prefectural Agriculture, Forestry and Fisheries Technology Research Center, Kyoto, Japan
| | - Kentaro Yano
- Laboratory of Bioinformatics, Department of Life Sciences, School of Agriculture, Meiji University, Kanagawa, Japan
| | - Takehiro Masumura
- Laboratory of Genetic Engineering, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
- Biotechnology Research Department, Kyoto Prefectural Agriculture, Forestry and Fisheries Technology Research Center, Kyoto, Japan
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9
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Gandullo J, Monreal JA, Álvarez R, Díaz I, García-Mauriño S, Echevarría C. Anionic Phospholipids Induce Conformational Changes in Phosphoenolpyruvate Carboxylase to Increase Sensitivity to Cathepsin Proteases. FRONTIERS IN PLANT SCIENCE 2019; 10:582. [PMID: 31143196 PMCID: PMC6521631 DOI: 10.3389/fpls.2019.00582] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 04/18/2019] [Indexed: 06/09/2023]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is a cytosolic, homotetrameric enzyme that serves a variety of functions in plants, acting as the primary form of CO2 fixation in the C4 photosynthesis pathway (C4-PEPC). In a previous work we have shown that C4-PEPC bind anionic phospholipids, resulting in PEPC inactivation. Also, we showed that PEPC can associate with membranes and to be partially proteolyzed. However, the mechanism controlling this remains unknown. Using semi purified-PEPC from sorghum leaf and a panel of PEPC-specific antibodies, we analyzed the conformational changes in PEPC induced by anionic phospholipids to cause the inactivation of the enzyme. Conformational changes observed involved the exposure of the C-terminus of PEPC from the native, active enzyme conformation. Investigation of the protease activity associated with PEPC demonstrated that cysteine proteases co-purify with the enzyme, with protease-specific substrates revealing cathepsin B and L as the major protease species present. The anionic phospholipid-induced C-terminal exposed conformation of PEPC appeared highly sensitive to the identified cathepsin protease activity and showed initial proteolysis of the enzyme beginning at the N-terminus. Taken together, these data provide the first evidence that anionic phospholipids promote not only the inactivation of the PEPC enzyme, but also its proteolysis.
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Affiliation(s)
- Jacinto Gandullo
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - José-Antonio Monreal
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Rosario Álvarez
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Isabel Díaz
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
| | - Sofía García-Mauriño
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Cristina Echevarría
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Seville, Spain
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10
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Zhao Y, Guo A, Wang Y, Hua J. Evolution of PEPC gene family in Gossypium reveals functional diversification and GhPEPC genes responding to abiotic stresses. Gene 2019; 698:61-71. [PMID: 30825597 DOI: 10.1016/j.gene.2019.02.061] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 02/10/2019] [Accepted: 02/23/2019] [Indexed: 12/24/2022]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) family genes play important roles in regulating plant growth and abiotic stress response. Based on the sequenced Gossypium genomes, we performed comprehensive analysis of PEPC homolog genes in cotton, which six, six, eleven and ten PEPC genes were identified in Gossypium arboreum (A2), G. raimondii (D5), G. hirsutum (AD1) and G. barbadense (AD2), respectively. These genes were divided into six subgroups: PEPC-i, PEPC-ii, PEPC-iii, PEPC-iv, PEPC-v and PEPC-vi; PEPC genes in each subgroup displayed conserved gene structure and motifs. Segmental duplication and whole genome duplication (WGD) events yielded the expansion of PEPC genes. Expression assays showed that the duplicated PEPC genes displayed diverse expression patterns, indicating that they experienced functional divergence. Of which, genes in PEPC-iv subgroup played crucial role for substrate distribution in cottonseed. Cis-elements, putative miRNAs and expression analyses showed that GhPEPC homologs might respond to abiotic stresses, expression levels of GhPEPC1 and GhPEPC2/GhPEPC2D genes were larger induced than other GhPEPC genes under cold, heat, salt, and drought stresses, indicating the crucial roles in abiotic stresses response. Present study serves new information to decipher the evolution and function of PEPC genes in Gossypium.
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Affiliation(s)
- Yanpeng Zhao
- Laboratory of Cotton Genetics, Genomics and Breeding, Beijing Key Laboratory of Crop Genetic Improvement, Key Laboratory of Crop Heterosis and Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
| | - Anhui Guo
- Laboratory of Cotton Genetics, Genomics and Breeding, Beijing Key Laboratory of Crop Genetic Improvement, Key Laboratory of Crop Heterosis and Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
| | - Yumei Wang
- Research Institute of Cash Crops, Hubei Academy of Agricultural Sciences, Wuhan 430064, Hubei, China
| | - Jinping Hua
- Laboratory of Cotton Genetics, Genomics and Breeding, Beijing Key Laboratory of Crop Genetic Improvement, Key Laboratory of Crop Heterosis and Utilization, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
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11
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Wei L, El Hajjami M, Shen C, You W, Lu Y, Li J, Jing X, Hu Q, Zhou W, Poetsch A, Xu J. Transcriptomic and proteomic responses to very low CO 2 suggest multiple carbon concentrating mechanisms in Nannochloropsis oceanica. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:168. [PMID: 31297156 PMCID: PMC6599299 DOI: 10.1186/s13068-019-1506-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 06/18/2019] [Indexed: 05/20/2023]
Abstract
BACKGROUND In industrial oleaginous microalgae such as Nannochloropsis spp., the key components of the carbon concentration mechanism (CCM) machineries are poorly defined, and how they are mobilized to facilitate cellular utilization of inorganic carbon remains elusive. RESULTS For Nannochloropsis oceanica, to unravel genes specifically induced by CO2 depletion which are thus potentially underpinning its CCMs, transcriptome, proteome and metabolome profiles were tracked over 0 h, 3 h, 6 h, 12 h and 24 h during cellular response from high CO2 level (HC; 50,000 ppm) to very low CO2 (VLC; 100 ppm). The activity of a biophysical CCM is evidenced based on induction of transcripts encoding a bicarbonate transporter and two carbonic anhydrases under VLC. Moreover, the presence of a potential biochemical CCM is supported by the upregulation of a number of key C4-like pathway enzymes in both protein abundance and enzymatic activity under VLC, consistent with a mitochondria-implicated C4-based CCM. Furthermore, a basal CCM underpinned by VLC-induced upregulation of photorespiration and downregulation of ornithine-citrulline shuttle and the ornithine urea cycles is likely present, which may be responsible for efficient recycling of mitochondrial CO2 for chloroplastic carbon fixation. CONCLUSIONS Nannochloropsis oceanica appears to mobilize a comprehensive set of CCMs in response to very low CO2. Its genes induced by the stress are quite distinct from those of Chlamydomonas reinhardtii and Phaeodactylum tricornutum, suggesting tightly regulated yet rather unique CCMs. These findings can serve the first step toward rational engineering of the CCMs for enhanced carbon fixation and biomass productivity in industrial microalgae.
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Affiliation(s)
- Li Wei
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong China
- University of Chinese Academy of Science, Beijing, China
| | - Mohamed El Hajjami
- Department of Plant Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Chen Shen
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong China
- University of Chinese Academy of Science, Beijing, China
| | - Wuxin You
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong China
- Department of Plant Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Yandu Lu
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong China
- University of Chinese Academy of Science, Beijing, China
| | - Jing Li
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong China
- University of Chinese Academy of Science, Beijing, China
| | - Xiaoyan Jing
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong China
- University of Chinese Academy of Science, Beijing, China
| | - Qiang Hu
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei China
- University of Chinese Academy of Science, Beijing, China
| | - Wenxu Zhou
- Department of Chemistry and Biochemistry, Center for Chemical Biology, Texas Tech University, Lubbock, TX USA
| | - Ansgar Poetsch
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong China
- Department of Plant Biochemistry, Ruhr University Bochum, Bochum, Germany
- School of Biomedical and Healthcare Sciences, University of Plymouth, Plymouth, UK
| | - Jian Xu
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong China
- University of Chinese Academy of Science, Beijing, China
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12
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Connell MB, Lee MJY, Li J, Plaxton WC, Jia Z. Structural and biochemical characterization of citrate binding to AtPPC3, a plant-type phosphoenolpyruvate carboxylase from Arabidopsis thaliana. J Struct Biol 2018; 204:507-512. [PMID: 30419358 DOI: 10.1016/j.jsb.2018.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/02/2018] [Accepted: 11/09/2018] [Indexed: 11/30/2022]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is a tightly regulated cytosolic enzyme situated at a crucial branch point of central plant metabolism. The structure of AtPPC3, a C3 PEPC isozyme of the model plant Arabidopsis thaliana, in complex with the inhibitors aspartate and citrate was solved at 2.2-Å resolution. This represents the first PEPC structure with citrate bound. Aspartate and citrate binding sites are in close proximity (5.1-5.3 Å) and interactions between citrate and specific residues were identified. Citrate functions as a mixed (allosteric) inhibitor as it reduced AtPPC3's Vmax while increasing Km(PEP) values. The PEP saturation data gave an excellent fit to the mixed inhibition model, yielding Ki and Ki' (citrate) values of 9.3 and 42.5 mM, respectively. Citrate and aspartate inhibition of AtPPC3 was non-additive, likely due to their closely positioned binding sites, their similar negative charge, and type of binding residues. Fewer interactions and lower affinity for citrate support its observed weaker inhibition of AtPPC3 relative to aspartate. Citrate does not appear to induce further conformational change beyond aspartate owing to the similar structural mechanism of inhibition. AtPPC3 largely exhibits root-specific expression in Arabidopsis, where it is markedly upregulated during stresses such as excessive salinity or nutritional Pi deprivation that necessitate large increases in anaplerotic PEP carboxylation. The cytosolic citrate concentration of potato tubers suggests that AtPPC3's inhibition by citrate may be physiologically relevant. Our results provide novel insights into the structural basis of allosteric PEPC control and the kinetic effects brought about upon inhibitor binding.
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Affiliation(s)
- Matthew B Connell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Michael J Y Lee
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Jerry Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - William C Plaxton
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada; Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada.
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada.
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13
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Poschenrieder C, Fernández JA, Rubio L, Pérez L, Terés J, Barceló J. Transport and Use of Bicarbonate in Plants: Current Knowledge and Challenges Ahead. Int J Mol Sci 2018; 19:E1352. [PMID: 29751549 PMCID: PMC5983714 DOI: 10.3390/ijms19051352] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 04/27/2018] [Accepted: 04/28/2018] [Indexed: 01/09/2023] Open
Abstract
Bicarbonate plays a fundamental role in the cell pH status in all organisms. In autotrophs, HCO₃− may further contribute to carbon concentration mechanisms (CCM). This is especially relevant in the CO₂-poor habitats of cyanobacteria, aquatic microalgae, and macrophytes. Photosynthesis of terrestrial plants can also benefit from CCM as evidenced by the evolution of C₄ and Crassulacean Acid Metabolism (CAM). The presence of HCO₃− in all organisms leads to more questions regarding the mechanisms of uptake and membrane transport in these different biological systems. This review aims to provide an overview of the transport and metabolic processes related to HCO₃− in microalgae, macroalgae, seagrasses, and terrestrial plants. HCO₃− transport in cyanobacteria and human cells is much better documented and is included for comparison. We further comment on the metabolic roles of HCO₃− in plants by focusing on the diversity and functions of carbonic anhydrases and PEP carboxylases as well as on the signaling role of CO₂/HCO₃− in stomatal guard cells. Plant responses to excess soil HCO₃− is briefly addressed. In conclusion, there are still considerable gaps in our knowledge of HCO₃− uptake and transport in plants that hamper the development of breeding strategies for both more efficient CCM and better HCO₃− tolerance in crop plants.
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Affiliation(s)
- Charlotte Poschenrieder
- Plant Physiology Lab., Bioscience Faculty, Universidad Autónoma de Barcelona, 08193 Barcelona, Spain.
| | - José Antonio Fernández
- Department Biologia. Vegetal, Campus Teatinos, Universidad de Málaga, 29071 Málaga, Spain.
| | - Lourdes Rubio
- Department Biologia. Vegetal, Campus Teatinos, Universidad de Málaga, 29071 Málaga, Spain.
| | - Laura Pérez
- Plant Physiology Lab., Bioscience Faculty, Universidad Autónoma de Barcelona, 08193 Barcelona, Spain.
| | - Joana Terés
- Plant Physiology Lab., Bioscience Faculty, Universidad Autónoma de Barcelona, 08193 Barcelona, Spain.
| | - Juan Barceló
- Plant Physiology Lab., Bioscience Faculty, Universidad Autónoma de Barcelona, 08193 Barcelona, Spain.
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14
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Ting MKY, She YM, Plaxton WC. Transcript profiling indicates a widespread role for bacterial-type phosphoenolpyruvate carboxylase in malate-accumulating sink tissues. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:5857-5869. [PMID: 29240945 PMCID: PMC5854131 DOI: 10.1093/jxb/erx399] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is an important regulatory enzyme situated at a key branch point of central plant metabolism. Plant genomes encode several plant-type PEPC (PTPC) isozymes, along with a distantly related bacterial-type PEPC (BTPC). BTPC is expressed at high levels in developing castor oil seeds where it tightly interacts with co-expressed PTPC polypeptides to form unusual hetero-octameric Class-2 PEPC complexes that are desensitized to allosteric inhibition by L-malate. Analysis of RNA-Seq and microarray transcriptome datasets revealed two distinct patterns of tissue-specific BTPC expression in vascular plants. Species such as Arabidopsis thaliana, strawberry, rice, maize, and poplar mainly exhibited pollen- or floral-specific BTPC expression. By contrast, BTPC transcripts were relatively abundant in developing castor, cotton, and soybean seeds, cassava tubers, as well as immature tomato, cucumber, grape, and avocado fruit. Immunoreactive 118 kDa BTPC polypeptides were detected on immunoblots of cucumber and tomato fruit extracts. Co-immunoprecipitation established that as in castor, BTPCs physically interact with endogenous PTPCs to form Class-2 PEPC complexes in tomato and cucumber fruit. We hypothesize that Class-2 PEPCs simultaneously maintain rapid anaplerotic PEP carboxylation and respiratory CO2 refixation in diverse, biosynthetically active sinks that accumulate high malate levels.
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Affiliation(s)
- Michael K Y Ting
- Department of Biology, Queen’s University, Kingston, Ontario, Canada
| | - Yi-Min She
- Centre for Biologics Evaluation Biologics and Genetic Therapies Directorate, Health Canada, Ottawa, Ontario, Canada
| | - William C Plaxton
- Department of Biology, Queen’s University, Kingston, Ontario, Canada
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- Correspondence:
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15
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Sui X, Shan N, Hu L, Zhang C, Yu C, Ren H, Turgeon R, Zhang Z. The complex character of photosynthesis in cucumber fruit. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:1625-1637. [PMID: 28369547 PMCID: PMC5441898 DOI: 10.1093/jxb/erx034] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The surface area of a mature green cucumber (Cucumis sativa L.) fruit is comparable with that of a functional leaf, but the characteristics of fruit photosynthesis and its contribution to growth are poorly understood. Here, the photosynthetic properties of two genotypes of cucumber (dark green and light green fruits) were studied using a combination of electron microscopy, immunogold enzyme localization, chlorophyll fluorescence imaging, isotope tracer, and fruit darkening techniques. Chlorophyll content of the exocarp is similar to that of leaves, but there are no distinctive palisade and spongy tissues. The efficiency of PSII is similar to that in leaves, but with lower non-photochemical quenching (NPQ). Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is found mainly in the exocarp, while phosphoenolpyruvate carboxylase (PEPC) is primarily localized to vascular bundles and placenta tissue. Rubisco and PEPC expression at both transcriptional and translational levels increases concurrently during fruit growth. The contribution of fruit photosynthesis in exocarp to its own C accumulation is 9.4%, while ~88% of respiratory CO2 in fruit was captured and re-fixed. Photosynthesis by cucumber fruits, through direct fixation of atmospheric CO2 and recapture of respired CO2, as verified by 14CO2 uptake and gas exchange, makes an important contribution to fruit growth.
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Affiliation(s)
- Xiaolei Sui
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Nan Shan
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Liping Hu
- Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Cankui Zhang
- Department of Agronomy, Purdue University, West Lafayette, IN 47907, USA
| | - Changqing Yu
- Ecological Laboratory, Ecotech Ecological Technology Ltd, Beijing 100190, China
| | - Huazhong Ren
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Robert Turgeon
- Plant Biology Section, Cornell University, Ithaca, NY 14853, USA
| | - Zhenxian Zhang
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Horticulture, China Agricultural University, Beijing 100193, China
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16
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O’Leary BM, Plaxton WC. Mechanisms and Functions of Post-translational Enzyme Modifications in the Organization and Control of Plant Respiratory Metabolism. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2017. [DOI: 10.1007/978-3-319-68703-2_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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17
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Brikis CJ, Zarei A, Trobacher CP, DeEll JR, Akama K, Mullen RT, Bozzo GG, Shelp BJ. Ancient Plant Glyoxylate/Succinic Semialdehyde Reductases: GLYR1s Are Cytosolic, Whereas GLYR2s Are Localized to Both Mitochondria and Plastids. FRONTIERS IN PLANT SCIENCE 2017; 8:601. [PMID: 28484477 PMCID: PMC5399074 DOI: 10.3389/fpls.2017.00601] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 04/03/2017] [Indexed: 05/18/2023]
Abstract
Plant NADPH-dependent glyoxylate/succinic semialdehyde reductases 1 and 2 (GLYR1 and GLYR2) are considered to be involved in detoxifying harmful aldehydes, thereby preserving plant health during exposure to various abiotic stresses. Phylogenetic analysis revealed that the two GLYR isoforms appeared in the plant lineage prior to the divergence of the Chlorophyta and Streptophyta, which occurred approximately 750 million years ago. Green fluorescent protein fusions of apple (Malus x domestica Borkh.), rice (Oryza sativa L.) and Arabidopsis thaliana [L.] Heynh GLYRs were transiently expressed in tobacco (Nicotiana tabaccum L.) suspension cells or Arabidopsis protoplasts, as well in methoxyfenozide-induced, stably transformed Arabidopsis seedlings. The localization of apple GLYR1 confirmed that this isoform is cytosolic, whereas apple, rice and Arabidopsis GLYR2s were localized to both mitochondria and plastids. These findings highlight the potential involvement of GLYRs within distinct compartments of the plant cell.
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Affiliation(s)
| | - Adel Zarei
- Department of Plant Agriculture, University of Guelph, GuelphON, Canada
| | | | - Jennifer R. DeEll
- Ontario Ministry of Agriculture Food and Rural Affairs, SimcoeON, Canada
| | - Kazuhito Akama
- Department of Biological Science, Shimane UniversityMatsue, Japan
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, GuelphON, Canada
| | - Gale G. Bozzo
- Department of Plant Agriculture, University of Guelph, GuelphON, Canada
| | - Barry J. Shelp
- Department of Plant Agriculture, University of Guelph, GuelphON, Canada
- *Correspondence: Barry J. Shelp,
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18
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Arabidopsis aldehyde dehydrogenase 10 family members confer salt tolerance through putrescine-derived 4-aminobutyrate (GABA) production. Sci Rep 2016; 6:35115. [PMID: 27725774 PMCID: PMC5057122 DOI: 10.1038/srep35115] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 09/26/2016] [Indexed: 11/26/2022] Open
Abstract
Polyamines represent a potential source of 4-aminobutyrate (GABA) in plants exposed to abiotic stress. Terminal catabolism of putrescine in Arabidopsis thaliana involves amine oxidase and the production of 4-aminobutanal, which is a substrate for NAD+-dependent aminoaldehyde dehydrogenase (AMADH). Here, two AMADH homologs were chosen (AtALDH10A8 and AtALDH10A9) as candidates for encoding 4-aminobutanal dehydrogenase activity for GABA synthesis. The two genes were cloned and soluble recombinant proteins were produced in Escherichia coli. The pH optima for activity and catalytic efficiency of recombinant AtALDH10A8 with 3-aminopropanal as substrate was 10.5 and 8.5, respectively, whereas the optima for AtALDH10A9 were approximately 9.5. Maximal activity and catalytic efficiency were obtained with NAD+ and 3-aminopropanal, followed by 4-aminobutanal; negligible activity was obtained with betaine aldehyde. NAD+ reduction was accompanied by the production of GABA and β-alanine, respectively, with 4-aminobutanal and 3-aminopropanal as substrates. Transient co-expression systems using Arabidopsis cell suspension protoplasts or onion epidermal cells and several organelle markers revealed that AtALDH10A9 was peroxisomal, but AtALDH10A8 was cytosolic, although the N-terminal 140 amino acid sequence of AtALDH10A8 localized to the plastid. Root growth of single loss-of-function mutants was more sensitive to salinity than wild-type plants, and this was accompanied by reduced GABA accumulation.
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19
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The calcium-dependent protein kinase RcCDPK2 phosphorylates sucrose synthase at Ser11 in developing castor oil seeds. Biochem J 2016; 473:3667-3682. [PMID: 27512054 DOI: 10.1042/bcj20160531] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 08/10/2016] [Indexed: 12/11/2022]
Abstract
Imported sucrose is cleaved by sucrose synthase (SUS) as a critical initial reaction in the biosynthesis of storage end-products by developing seeds. Although SUS is phosphorylated at a conserved seryl residue by an apparent CDPK (Ca2+-dependent protein kinase) in diverse plant tissues, the functions and mechanistic details of this process remain obscure. Thus, the native CDPK that phosphorylates RcSUS1 (Ricinus communis SUS1) at Ser11 in developing COS (castor oil seeds) was highly purified and identified as RcCDPK2 by MS/MS. Purified RcSUS1-K (-kinase) and heterologously expressed RcCDPK2 catalyzed Ca2+-dependent Ser11 phosphorylation of RcSUS1 and its corresponding dephosphopeptide, while exhibiting a high affinity for free Ca2+ ions [K0.5(Ca2+) < 0.4 µM]. RcSUS1-K activity, RcCDPK2 expression, and RcSUS1 Ser11 phosphorylation peaked during early COS development and then declined in parallel. The elimination of sucrose import via fruit excision triggered RcSUS1 dephosphorylation but did not alter RcSUS1-K activity, suggesting a link between sucrose signaling and posttranslational RcCDPK2 control. Both RcCDPK2-mCherry and RcSUS1-EYFP co-localized throughout the cytosol when transiently co-expressed in tobacco suspension cells, although RcCDPK2-mCherry was also partially localized to the nucleus. Subcellular fractionation revealed that ∼20% of RcSUS1-K activity associates with microsomal membranes in developing COS, as does RcSUS1. In contrast with RcCDPK1, which catalyzes inhibitory phosphorylation of COS bacterial-type phosphoenolpyruvate carboxylase at Ser451, RcCDPK2 exhibited broad substrate specificity, a wide pH-activity profile centered at pH 8.5, and insensitivity to metabolite effectors or thiol redox status. Our combined results indicate a possible link between cytosolic Ca2+-signaling and the control of photosynthate partitioning during COS development.
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Ruiz-Ballesta I, Baena G, Gandullo J, Wang L, She YM, Plaxton WC, Echevarría C. New insights into the post-translational modification of multiple phosphoenolpyruvate carboxylase isoenzymes by phosphorylation and monoubiquitination during sorghum seed development and germination. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3523-36. [PMID: 27194739 PMCID: PMC4892742 DOI: 10.1093/jxb/erw186] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Phosphoenolpyruvate carboxylase (PEPC; E.C. 4.1.1.31) was characterized in developing and germinating sorghum seeds, focusing on the transcript and polypeptide abundance of multiple plant-type phosphoenolpyruvate carboxylase (PTPC) genes, and the post-translational modification of each isoenzyme by phosphorylation versus monoubiquitination during germination. We observed high levels of SbPPC4 (Sb07g014960) transcripts during early development (stage I), and extensive transcript abundance of SbPPC2 (Sb02g021090) and SbPPC3 (Sb04g008720) throughout the entire life cycle of the seed. Although tandem mass spectrometry (MS) analysis of immunopurified PTPC indicated that four different PTPC isoenzymes were expressed in the developing and germinating seeds, SbPPC3 was the most abundant isozyme of the developing seed, and of the embryo and the aleurone layer of germinating seeds. In vivo phosphorylation of the different PTPC isoenzymes at their conserved N-terminal seryl phosphorylation site during germination was also established by MS/MS analysis. Furthermore, three of the four isoenzymes were partially monoubiquitinated, with MS/MS pinpointing SbPPC2 and SbPPC3 monoubiquitination at the conserved Lys-630 and Lys-624 residues, respectively. Our results demonstrate that monoubiquitination and phosphorylation simultaneously occur in vivo with different PTPC isozymes during seed germination. In addition, we show that PTPC monoubiquitination in germinating sorghum seeds always increases at stage II (emergence of the radicle), is maintained during the aerobic period of rapid cell division and reserve mobilization, and remains relatively constant until stage IV-V when coleoptiles initiate the formation of the photosynthetic tissues.
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Affiliation(s)
- Isabel Ruiz-Ballesta
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Avda Reina Mercedes nº 6, 41012 Sevilla, Spain
| | - Guillermo Baena
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Avda Reina Mercedes nº 6, 41012 Sevilla, Spain
| | - Jacinto Gandullo
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Avda Reina Mercedes nº 6, 41012 Sevilla, Spain
| | - Liqun Wang
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, 3888 Chenhua Road, Shanghai 201602, China State Key Laboratory of Crop Genetics and Germplasm Enhancement, Soybean Research Institute, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Yi-Min She
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, 3888 Chenhua Road, Shanghai 201602, China
| | | | - Cristina Echevarría
- Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Avda Reina Mercedes nº 6, 41012 Sevilla, Spain
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Deng H, Zhang LS, Zhang GQ, Zheng BQ, Liu ZJ, Wang Y. Evolutionary history of PEPC genes in green plants: Implications for the evolution of CAM in orchids. Mol Phylogenet Evol 2016; 94:559-564. [DOI: 10.1016/j.ympev.2015.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 10/07/2015] [Accepted: 10/08/2015] [Indexed: 11/15/2022]
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22
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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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Muramatsu M, Suzuki R, Yamazaki T, Miyao M. Comparison of plant-type phosphoenolpyruvate carboxylases from rice: identification of two plant-specific regulatory regions of the allosteric enzyme. PLANT & CELL PHYSIOLOGY 2015; 56:468-480. [PMID: 25505033 DOI: 10.1093/pcp/pcu189] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is a key enzyme of primary metabolism in bacteria, algae and vascular plants, and it undergoes allosteric regulation by various metabolic effectors. Rice (Oryza sativa) has five plant-type PEPCs, four cytosolic and one chloroplastic. We investigated their kinetic properties using recombinant proteins and found that, like most plant-type PEPCs, rice cytosolic isozymes were activated by glucose 6-phosphate and by alkaline pH. In contrast, no such activation was observed for the chloroplastic isozyme, Osppc4. In addition, Osppc4 showed low affinity for the substrate phosphoenolpyruvate (PEP) and very low sensitivities to allosteric inhibitors aspartate and glutamate. By comparing the isozyme amino acid sequences and three-dimensional structures simulated on the basis of the reported crystal structures, we identified two regions where Osppc4 has unique features that can be expected to affect its kinetic properties. One is the N-terminal extension; replacement of the extension of Osppc2a (cytosolic) with that from Osppc4 reduced the aspartate and glutamate sensitivities to about one-tenth of the wild-type values but left the PEP affinity unaffected. The other is the N-terminal loop, in which a conserved lysine at the N-terminal end is replaced with a glutamate-alanine pair in Osppc4. Replacement of the lysine of Osppc2a with glutamate-alanine lowered the PEP affinity to a quarter of the wild-type level (down to the Osppc4 level), without affecting inhibitor sensitivity. Both the N-terminal extension and the N-terminal loop are specific to plant-type PEPCs, suggesting that plant-type isozymes acquired these regions so that their activity could be regulated properly at the sites where they function.
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Affiliation(s)
- Masayuki Muramatsu
- Functional Plant Research Unit, National Institute of Agrobiological Sciences, Kannondai, Tsukuba, 305-8602 Japan
| | - Rintaro Suzuki
- Biomolecular Research Unit, National Institute of Agrobiological Sciences, Kannondai, Tsukuba, 305-8602 Japan
| | - Toshimasa Yamazaki
- Biomolecular Research Unit, National Institute of Agrobiological Sciences, Kannondai, Tsukuba, 305-8602 Japan
| | - Mitsue Miyao
- Functional Plant Research Unit, National Institute of Agrobiological Sciences, Kannondai, Tsukuba, 305-8602 Japan
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Zarei A, Trobacher CP, Cooke AR, Meyers AJ, Hall JC, Shelp BJ. Apple fruit copper amine oxidase isoforms: peroxisomal MdAO1 prefers diamines as substrates, whereas extracellular MdAO2 exclusively utilizes monoamines. PLANT & CELL PHYSIOLOGY 2015; 56:137-47. [PMID: 25378687 DOI: 10.1093/pcp/pcu155] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
4-Aminobutyrate (GABA) accumulates in apple fruit during controlled atmosphere storage. A potential source of GABA is the polyamine putrescine, which can be oxidized via copper-containing amine oxidase (CuAO), resulting in the production 4-aminobutanal/Δ(1)-pyrroline, with the consumption of O2 and release of H2O2 and ammonia. Five putative CuAO genes (MdAO genes) were cloned from apple (Malus domestica Borkh. cv. Empire) fruit, and the deduced amino acid sequences found to contain the active sites typically conserved in CuAOs. Genes encoding two of these enzymes, MdAO1 and MdAO2, were highly expressed in apple fruit and selected for further analysis. Amino acid sequence analysis predicted the presence of a C-terminal peroxisomal targeting signal 1 tripeptide in MdAO1 and an N-terminal signal peptide and N-glycosylation site in MdAO2. Transient expression of green fluorescent fusion proteins in Arabidopsis protoplasts or onion epidermal cells revealed a peroxisomal localization for MdAO1 and an extracellular localization for MdAO2. The enzymatic activities of purified recombinant MdAO1 and MdAO2 were measured continuously as H2O2 production using a coupled reaction. MdAO1 did not use monoamines or polyamines and displayed high catalytic efficiency for 1,3-diaminopropane, putrescine and cadaverine, whereas MdAO2 exclusively utilized aliphatic and aromatic monoamines, including 2-phenylethylamine and tyramine. Together, these results indicate that MdAO1 may contribute to GABA production via putrescine oxidation in the peroxisome of apple fruit under controlled atmosphere conditions. MdAO2 seems to be involved in deamination of 2-phenylethylamine, which is a step in the biosynthesis of 2-phenylethanol, a contributor to fruit flavor and flower fragrance.
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Affiliation(s)
- Adel Zarei
- Department of Plant Agriculture, University of Guelph, 50 Stone Road E, Guelph, Canada N1G 2W1
| | - Christopher P Trobacher
- Department of Plant Agriculture, University of Guelph, 50 Stone Road E, Guelph, Canada N1G 2W1
| | - Alison R Cooke
- Department of Plant Agriculture, University of Guelph, 50 Stone Road E, Guelph, Canada N1G 2W1
| | - Ashley J Meyers
- School of Environmental Sciences, University of Guelph, 50 Stone Road E, Guelph, Canada N1G 2W1
| | - J Christopher Hall
- School of Environmental Sciences, University of Guelph, 50 Stone Road E, Guelph, Canada N1G 2W1
| | - Barry J Shelp
- Department of Plant Agriculture, University of Guelph, 50 Stone Road E, Guelph, Canada N1G 2W1
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Fedosejevs ET, Ying S, Park J, Anderson EM, Mullen RT, She YM, Plaxton WC. Biochemical and molecular characterization of RcSUS1, a cytosolic sucrose synthase phosphorylated in vivo at serine 11 in developing castor oil seeds. J Biol Chem 2014; 289:33412-24. [PMID: 25313400 PMCID: PMC4246097 DOI: 10.1074/jbc.m114.585554] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 10/06/2014] [Indexed: 11/06/2022] Open
Abstract
Sucrose synthase (SUS) catalyzes the UDP-dependent cleavage of sucrose into UDP-glucose and fructose and has become an important target for improving seed crops via metabolic engineering. A UDP-specific SUS homotetramer composed of 93-kDa subunits was purified to homogeneity from the triacylglyceride-rich endosperm of developing castor oil seeds (COS) and identified as RcSUS1 by mass spectrometry. RcSUS1 transcripts peaked during early development, whereas levels of SUS activity and immunoreactive 93-kDa SUS polypeptides maximized during mid-development, becoming undetectable in fully mature COS. The cytosolic location of the enzyme was established following transient expression of RcSUS1-enhanced YFP in tobacco suspension cells and fluorescence microscopy. Immunological studies using anti-phosphosite-specific antibodies revealed dynamic and high stoichiometric in vivo phosphorylation of RcSUS1 at its conserved Ser-11 residue during COS development. Incorporation of (32)P(i) from [γ-(32)P]ATP into a RcSUS1 peptide substrate, alongside a phosphosite-specific ELISA assay, established the presence of calcium-dependent RcSUS1 (Ser-11) kinase activity. Approximately 10% of RcSUS1 was associated with COS microsomal membranes and was hypophosphorylated relative to the remainder of RcSUS1 that partitioned into the soluble, cytosolic fraction. Elimination of sucrose supply caused by excision of intact pods of developing COS abolished RcSUS1 transcription while triggering the progressive dephosphorylation of RcSUS1 in planta. This did not influence the proportion of RcSUS1 associated with microsomal membranes but instead correlated with a subsequent marked decline in SUS activity and immunoreactive RcSUS1 polypeptides. Phosphorylation at Ser-11 appears to protect RcSUS1 from proteolysis, rather than influence its kinetic properties or partitioning between the soluble cytosol and microsomal membranes.
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Affiliation(s)
| | | | - Joonho Park
- the Department of Fine Chemistry, Seoul National University of Science and Technology, Nowon-Gu, Seoul 139-743, Korea
| | - Erin M Anderson
- the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada, and
| | - Robert T Mullen
- the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada, and
| | - Yi-Min She
- the Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai 201602, China
| | - William C Plaxton
- From the Departments of Biology and Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada,
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Phosphorylation of bacterial-type phosphoenolpyruvate carboxylase by a Ca2+-dependent protein kinase suggests a link between Ca2+ signalling and anaplerotic pathway control in developing castor oil seeds. Biochem J 2014; 458:109-18. [PMID: 24266766 DOI: 10.1042/bj20131191] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The aim of the present study was to characterize the native protein kinase [BTPC (bacterial-type phosphoenolpyruvate carboxylase)-K (BTPC Ser451 kinase)] that in vivo phosphorylates Ser451 of the BTPC subunits of an unusual Class-2 PEP (phosphoenolpyruvate) carboxylase hetero-octameric complex of developing COS (castor oil seeds). COS BTPC-K was highly purified by PEG fractionation and hydrophobic size-exclusion anion-exchange and affinity chromatographies. BTPC-K phosphorylated BTPC strictly at Ser451 (Km=1.0 μM; pH optimum=7.3), a conserved target residue occurring within an intrinsically disordered region, as well as the protein histone III-S (Km=1.7 μM), but not a COS plant-type PEP carboxylase or sucrose synthase or α-casein. Its activity was Ca2+- (K0.5=2.7 μM) and ATP- (Km=6.6 μM) dependent, and markedly inhibited by trifluoperazine, 3-phosphoglycerate and PEP, but insensitive to calmodulin or 14-3-3 proteins. BTPC-K exhibited a native molecular mass of ~63 kDa and was soluble rather than membrane-bound. Inactivation and reactivation occurred upon BTPC-K's incubation with GSSG and then DTT respectively. Ser451 phosphorylation by BTPC-K inhibited BTPC activity by ~50% when assayed under suboptimal conditions (pH 7.3, 1 mM PEP and 10 mM L-malate). Our collective results indicate a possible link between cytosolic Ca2+ signalling and anaplerotic flux control in developing COS.
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Stitt M, Gibon Y. Why measure enzyme activities in the era of systems biology? TRENDS IN PLANT SCIENCE 2014; 19:256-65. [PMID: 24332227 DOI: 10.1016/j.tplants.2013.11.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 11/05/2013] [Accepted: 11/08/2013] [Indexed: 05/22/2023]
Abstract
Information about the abundance and biological activities of proteins is essential to reveal how genes affect phenotypes. Over the past decade, mass spectrometry (MS)-based proteomics has revolutionized the identification and quantification of proteins, and the detection of post-translational modifications. Interpretation of proteomics data depends on information about the biological activities of proteins, which has created a bottleneck in research. This review focuses on enzymes in central metabolism. We examine the methods used for measuring enzyme activities, and discuss how these methods provide information about the kinetic and regulatory properties of enzymes, their turnover, and how this information can be integrated into metabolic models. We also discuss how robotized assays could enable the genetic networks that control enzyme abundance to be analyzed.
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Affiliation(s)
- Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam-Golm, Germany.
| | - Yves Gibon
- INRA, University of Bordeaux, UMR 1332 Fruit Biology and Pathology, F-33883 Villenave d'Ornon, France
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28
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Doubnerová Hýsková V, Miedzińska L, Dobrá J, Vankova R, Ryšlavá H. Phosphoenolpyruvate carboxylase, NADP-malic enzyme, and pyruvate, phosphate dikinase are involved in the acclimation of Nicotiana tabacum L. to drought stress. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:19-25. [PMID: 24484954 DOI: 10.1016/j.jplph.2013.10.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 09/24/2013] [Accepted: 10/07/2013] [Indexed: 05/21/2023]
Abstract
Drought stress is one of the most frequent forms of abiotic stresses, which occurs under condition of limited water availability. In this work, the possible participation of phosphoenolpyruvate carboxylase (EC 4.1.1.31; PEPC), NADP-malic enzyme (EC 1.1.1.40; NADP-ME), and pyruvate, phosphate dikinase (EC 2.7.9.1; PPDK) in response to drought of tobacco plants (Nicotiana tabacum L., cv. W38) was investigated. Enzyme specific activities in tobacco leaves of drought stressed plants were significantly increased after 11 days of stress, PEPC 2.3-fold, NADP-ME 3.9-fold, and PPDK 2.7-fold compared to control plants. The regulation of PEPC and NADP-ME activities were studied on transcriptional level by the quantitative RT PCR and on translational level - immunochemically. The amount of NADP-ME protein and transcription of mRNA for chloroplastic NADP-ME isoform were increased indicating their enhanced synthesis de novo. On the other hand, mRNA for cytosolic isoform of NADP-ME was decreased. The changes in PEPC protein and PEPC mRNA were not substantial. Therefore regulation of PEPC activity by phosphorylation was evaluated and found to be involved in the stress response. During recovery, activities of the tested enzymes returned close to their basal levels.
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Affiliation(s)
- Veronika Doubnerová Hýsková
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, Prague 2, 128 40, Czech Republic.
| | - Lucia Miedzińska
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, Prague 2, 128 40, Czech Republic
| | - Jana Dobrá
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, Praha 6, 165 02, Czech Republic
| | - Radomira Vankova
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, Praha 6, 165 02, Czech Republic
| | - Helena Ryšlavá
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, Prague 2, 128 40, Czech Republic
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Shane MW, Fedosejevs ET, Plaxton WC. Reciprocal control of anaplerotic phosphoenolpyruvate carboxylase by in vivo monoubiquitination and phosphorylation in developing proteoid roots of phosphate-deficient harsh hakea. PLANT PHYSIOLOGY 2013; 161:1634-44. [PMID: 23407057 PMCID: PMC3613444 DOI: 10.1104/pp.112.213496] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 02/12/2013] [Indexed: 05/08/2023]
Abstract
Accumulating evidence indicates important functions for phosphoenolpyruvate (PEP) carboxylase (PEPC) in inorganic phosphate (Pi)-starved plants. This includes controlling the production of organic acid anions (malate, citrate) that are excreted in copious amounts by proteoid roots of nonmycorrhizal species such as harsh hakea (Hakea prostrata). This, in turn, enhances the bioavailability of mineral-bound Pi by solubilizing Al(3+), Fe(3+), and Ca(2+) phosphates in the rhizosphere. Harsh hakea thrives in the nutrient-impoverished, ancient soils of southwestern Australia. Proteoid roots from Pi-starved harsh hakea were analyzed over 20 d of development to correlate changes in malate and citrate exudation with PEPC activity, posttranslational modifications (inhibitory monoubiquitination versus activatory phosphorylation), and kinetic/allosteric properties. Immature proteoid roots contained an equivalent ratio of monoubiquitinated 110-kD and phosphorylated 107-kD PEPC polypeptides (p110 and p107, respectively). PEPC purification, immunoblotting, and mass spectrometry indicated that p110 and p107 are subunits of a 430-kD heterotetramer and that they both originate from the same plant-type PEPC gene. Incubation with a deubiquitinating enzyme converted the p110:p107 PEPC heterotetramer of immature proteoid roots into a p107 homotetramer while significantly increasing the enzyme's activity under suboptimal but physiologically relevant assay conditions. Proteoid root maturation was paralleled by PEPC activation (e.g. reduced Km [PEP] coupled with elevated I50 [malate and Asp] values) via in vivo deubiquitination of p110 to p107, and subsequent phosphorylation of the deubiquitinated subunits. This novel mechanism of posttranslational control is hypothesized to contribute to the massive synthesis and excretion of organic acid anions that dominates the carbon metabolism of the mature proteoid roots.
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Affiliation(s)
- Michael W Shane
- School of Plant Biology, Faculty of Science, University of Western Australia, Crawley, Western Australia 6009, Australia.
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30
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Sweetlove LJ, Fernie AR. The spatial organization of metabolism within the plant cell. ANNUAL REVIEW OF PLANT BIOLOGY 2013; 64:723-46. [PMID: 23330793 DOI: 10.1146/annurev-arplant-050312-120233] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Identifying the correct subcellular locations for all enzymes and metabolites in plant metabolic networks is a major challenge, but is critically important for the success of the new generation of large-scale metabolic models that are driving a network-level appreciation of metabolic behavior. Even though the subcellular compartmentation of many central metabolic processes is thought to be well understood, recent gene-by-gene studies have revealed several unexpected enzyme localizations. Metabolite transport between subcellular compartments is crucial because it fundamentally affects the metabolic network structure. Although new metabolite transporters are being steadily identified, modeling work suggests that we have barely scratched the surface of the catalog of intracellular metabolite transporter proteins. In addition to compartmentation among organelles, it is increasingly apparent that microcompartment formation via the interactions of enzyme groups with intracellular membranes, the cytoskeleton, or other proteins is an important regulatory mechanism. In particular, this mechanism can promote metabolite channeling within the metabolic microcompartment, which can help control reaction specificity as well as dictate flux routes through the network. This has clear relevance for both synthetic biology in general and the engineering of plant metabolic networks in particular.
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Affiliation(s)
- Lee J Sweetlove
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.
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