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Eceiza MV, Jimenez-Martinez C, Gil-Monreal M, Barco-Antoñanzas M, Font-Farre M, Huybrechts M, van der Hoorn RL, Cuypers A, Royuela M, Zabalza A. Role of glutathione S-transferases in the mode of action of herbicides that inhibit amino acid synthesis in Amaranthus palmeri. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 208:108506. [PMID: 38461753 DOI: 10.1016/j.plaphy.2024.108506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/29/2024] [Accepted: 03/04/2024] [Indexed: 03/12/2024]
Abstract
Acetolactate synthase inhibitors (ALS inhibitors) and glyphosate are two classes of herbicides that act by inhibiting an enzyme in the biosynthetic pathway of branched-chain or aromatic amino acids, respectively. Besides amino acid synthesis inhibition, both herbicides trigger similar physiological effects in plants. The main aim of this study was to evaluate the role of glutathione metabolism, with special emphasis on glutathione S-transferases (GSTs), in the mode of action of glyphosate and ALS inhibitors in Amaranthus palmeri. For that purpose, plants belonging to a glyphosate-sensitive (GLS) and a glyphosate-resistant (GLR) population were treated with different doses of glyphosate, and plants belonging to an ALS-inhibitor sensitive (AIS) and an ALS-inhibitor resistant (AIR) population were treated with different doses of the ALS inhibitor nicosulfuron. Glutathione-related contents, GST activity, and related gene expressions (glutamate-cysteine ligase, glutathione reductase, Phi GST and Tau GST) were analysed in leaves. According to the results of the analytical determinations, there were virtually no basal differences between GLS and GLR plants or between AIS and AIR plants. Glutathione synthesis and turnover did not follow a clear pattern in response to herbicides, but GST activity and gene expression (especially Phi GSTs) increased with both herbicides in treated sensitive plants, possibly related to the rocketing H2O2 accumulation. As GSTs offered the clearest results, these were further investigated with a multiple resistant (MR) population, compressing target-site resistance to both glyphosate and the ALS inhibitor pyrithiobac. As in single-resistant plants, measured parameters in the MR population were unaffected by herbicides, meaning that the increase in GST activity and expression occurs due to herbicide interactions with the target enzymes.
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Affiliation(s)
- Mikel V Eceiza
- Institute for Multidisciplinary Research in Applied Biology (IMAB), Universidad Pública de Navarra (UPNA), Campus de Arrosadia, Pamplona, Spain
| | - Clara Jimenez-Martinez
- Institute for Multidisciplinary Research in Applied Biology (IMAB), Universidad Pública de Navarra (UPNA), Campus de Arrosadia, Pamplona, Spain
| | - Miriam Gil-Monreal
- Institute for Multidisciplinary Research in Applied Biology (IMAB), Universidad Pública de Navarra (UPNA), Campus de Arrosadia, Pamplona, Spain
| | - María Barco-Antoñanzas
- Institute for Multidisciplinary Research in Applied Biology (IMAB), Universidad Pública de Navarra (UPNA), Campus de Arrosadia, Pamplona, Spain
| | - Maria Font-Farre
- The Plant Chemetics Laboratory, Department of Biology Sciences, University of Oxford, Oxford, UK
| | - Michiel Huybrechts
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, B-3590, Diepenbeek, Belgium
| | - RenierA L van der Hoorn
- The Plant Chemetics Laboratory, Department of Biology Sciences, University of Oxford, Oxford, UK
| | - Ann Cuypers
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, B-3590, Diepenbeek, Belgium
| | - Mercedes Royuela
- Institute for Multidisciplinary Research in Applied Biology (IMAB), Universidad Pública de Navarra (UPNA), Campus de Arrosadia, Pamplona, Spain
| | - Ana Zabalza
- Institute for Multidisciplinary Research in Applied Biology (IMAB), Universidad Pública de Navarra (UPNA), Campus de Arrosadia, Pamplona, Spain.
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Kharwar S, Mishra AK. Nitrogen and Redox Metabolism in Cyanobacterium Anabaena sp. PCC 7120 Exposed to Different Sulfate Regimes. Curr Microbiol 2023; 80:265. [PMID: 37393301 DOI: 10.1007/s00284-023-03374-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 06/13/2023] [Indexed: 07/03/2023]
Abstract
Sulfur is an important key nutrient required for the growth and development of cyanobacteria. Several reports showed the effect of sulfate limitation in unicellular and filamentous cyanobacteria, but such studies have not yet been reported in heterocytous cyanobacteria to ascribe the mechanisms of nitrogen and thiol metabolisms. Thus, the present work was carried out to appraise the impacts of sulfate limitation on nitrogen and thiol metabolisms in Anabaena sp. PCC 7120 by analyzing the contents as well as enzymes of nitrogen and thiol metabolisms. Cells of Anabaena sp. PCC 7120 were exposed to different regimes of sulfate, i.e., 300, 30, 3, and 0 µM. Application of reduced concentration of sulfate showed negative impact on the cyanobacterium. Sulfate-limiting conditions reduces nitrogen-containing compounds in the cells of Anabaena. Additionally, reduced activities of nitrogen metabolic enzymes represented the role of sulfate in nitrogen metabolism. However, decreased activities of thiol metabolic enzymes indicated that sulfate-limited cyanobacterial cells have lower amount of glutathione and total thiol contents. Reduced accumulation of thiol components in the stressed cells indicated that sulfate-limited cells have lower ability to withstand stressful condition. Hence, Anabaena displays differential response to different concentrations of sulfate, and thus, stipulated that sulfur plays an important role in nitrogen and thiol metabolisms. To the best of our knowledge, this is the first report demonstrating the impact of sulfate stress on nitrogen and redox metabolisms in heterocytous cyanobacteria. This preliminary study provides a baseline idea that may help improve the production of paddy.
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Affiliation(s)
- Surbhi Kharwar
- Laboratory of Microbial Genetics, Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
- Department of Botany, University of Lucknow, Lucknow, 226007, India
| | - Arun Kumar Mishra
- Laboratory of Microbial Genetics, Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
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3
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Wang M, Ogé L, Pérez Garcia MD, Launay-Avon A, Clément G, Le Gourrierec J, Hamama L, Sakr S. Antagonistic Effect of Sucrose Availability and Auxin on Rosa Axillary Bud Metabolism and Signaling, Based on the Transcriptomics and Metabolomics Analysis. FRONTIERS IN PLANT SCIENCE 2022; 13:830840. [PMID: 35392520 PMCID: PMC8982072 DOI: 10.3389/fpls.2022.830840] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
Shoot branching is crucial for successful plant development and plant response to environmental factors. Extensive investigations have revealed the involvement of an intricate regulatory network including hormones and sugars. Recent studies have demonstrated that two major systemic regulators-auxin and sugar-antagonistically regulate plant branching. However, little is known regarding the molecular mechanisms involved in this crosstalk. We carried out two complementary untargeted approaches-RNA-seq and metabolomics-on explant stem buds fed with different concentrations of auxin and sucrose resulting in dormant and non-dormant buds. Buds responded to the combined effect of auxin and sugar by massive reprogramming of the transcriptome and metabolome. The antagonistic effect of sucrose and auxin targeted several important physiological processes, including sink strength, the amino acid metabolism, the sulfate metabolism, ribosome biogenesis, the nucleic acid metabolism, and phytohormone signaling. Further experiments revealed a role of the TOR-kinase signaling pathway in bud outgrowth through at least downregulation of Rosa hybrida BRANCHED1 (RhBRC1). These new findings represent a cornerstone to further investigate the diverse molecular mechanisms that drive the integration of endogenous factors during shoot branching.
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Affiliation(s)
- Ming Wang
- Dryland-Technology Key Laboratory of Shandong Province, College of Agronomy, Qingdao Agricultural University, Qingdao, China
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
| | - Laurent Ogé
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
| | | | - Alexandra Launay-Avon
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Université Paris-Sud, Université d’Evry, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Gilles Clément
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Jose Le Gourrierec
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
| | - Latifa Hamama
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
| | - Soulaiman Sakr
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
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A molecular switch in sulfur metabolism to reduce arsenic and enrich selenium in rice grain. Nat Commun 2021; 12:1392. [PMID: 33654102 PMCID: PMC7925690 DOI: 10.1038/s41467-021-21282-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 01/15/2021] [Indexed: 12/18/2022] Open
Abstract
Rice grains typically contain high levels of toxic arsenic but low levels of the essential micronutrient selenium. Anthropogenic arsenic contamination of paddy soils exacerbates arsenic toxicity in rice crops resulting in substantial yield losses. Here, we report the identification of the gain-of-function arsenite tolerant 1 (astol1) mutant of rice that benefits from enhanced sulfur and selenium assimilation, arsenic tolerance, and decreased arsenic accumulation in grains. The astol1 mutation promotes the physical interaction of the chloroplast-localized O-acetylserine (thiol) lyase protein with its interaction partner serine-acetyltransferase in the cysteine synthase complex. Activation of the serine-acetyltransferase in this complex promotes the uptake of sulfate and selenium and enhances the production of cysteine, glutathione, and phytochelatins, resulting in increased tolerance and decreased translocation of arsenic to grains. Our findings uncover the pivotal sensing-function of the cysteine synthase complex in plastids for optimizing stress resilience and grain quality by regulating a fundamental macronutrient assimilation pathway. Contamination of paddy soils can lead to toxic arsenic accumulation in rice grains and low levels of the micronutrient selenium. Here the authors show that a gain of function mutant affecting an O-acetylserine (thiol) lyase enhances sulfur and selenium assimilation while reducing arsenic accumulation in grains.
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Whitcomb SJ, Rakpenthai A, Brückner F, Fischer A, Parmar S, Erban A, Kopka J, Hawkesford MJ, Hoefgen R. Cysteine and Methionine Biosynthetic Enzymes Have Distinct Effects on Seed Nutritional Quality and on Molecular Phenotypes Associated With Accumulation of a Methionine-Rich Seed Storage Protein in Rice. FRONTIERS IN PLANT SCIENCE 2020; 11:1118. [PMID: 32793268 PMCID: PMC7387578 DOI: 10.3389/fpls.2020.01118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/07/2020] [Indexed: 06/11/2023]
Abstract
Staple crops in human and livestock diets suffer from deficiencies in certain "essential" amino acids including methionine. With the goal of increasing methionine in rice seed, we generated a pair of "Push × Pull" double transgenic lines, each containing a methionine-dense seed storage protein (2S albumin from sunflower, HaSSA) and an exogenous enzyme for either methionine (feedback desensitized cystathionine gamma synthase from Arabidopsis, AtD-CGS) or cysteine (serine acetyltransferase from E. coli, EcSAT) biosynthesis. In both double transgenic lines, the total seed methionine content was approximately 50% higher than in their untransformed parental line, Oryza sativa ssp. japonica cv. Taipei 309. HaSSA-containing rice seeds were reported to display an altered seed protein profile, speculatively due to insufficient sulfur amino acid content. However, here we present data suggesting that this may result from an overloaded protein folding machinery in the endoplasmic reticulum rather than primarily from redistribution of limited methionine from endogenous seed proteins to HaSSA. We hypothesize that HaSSA-associated endoplasmic reticulum stress results in redox perturbations that negatively impact sulfate reduction to cysteine, and we speculate that this is mitigated by EcSAT-associated increased sulfur import into the seed, which facilitates additional synthesis of cysteine and glutathione. The data presented here reveal challenges associated with increasing the methionine content in rice seed, including what may be relatively low protein folding capacity in the endoplasmic reticulum and an insufficient pool of sulfate available for additional cysteine and methionine synthesis. We propose that future approaches to further improve the methionine content in rice should focus on increasing seed sulfur loading and avoiding the accumulation of unfolded proteins in the endoplasmic reticulum. Oryza sativa ssp. japonica: urn:lsid:ipni.org:names:60471378-2.
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Affiliation(s)
- Sarah J. Whitcomb
- Laboratory of Amino Acid and Sulfur Metabolism, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Apidet Rakpenthai
- Laboratory of Amino Acid and Sulfur Metabolism, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Franziska Brückner
- Laboratory of Amino Acid and Sulfur Metabolism, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Axel Fischer
- Bioinformatics Infrastructure Group, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Saroj Parmar
- Plant Sciences Department, Rothamsted Research, Harpenden, United Kingdom
| | - Alexander Erban
- Applied Metabolome Analysis Infrastructure Group, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Joachim Kopka
- Applied Metabolome Analysis Infrastructure Group, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | | | - Rainer Hoefgen
- Laboratory of Amino Acid and Sulfur Metabolism, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
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Rajab H, Khan MS, Wirtz M, Malagoli M, Qahar F, Hell R. Sulfur metabolic engineering enhances cadmium stress tolerance and root to shoot iron translocation in Brassica napus L. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 152:32-43. [PMID: 32387912 DOI: 10.1016/j.plaphy.2020.04.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/12/2020] [Accepted: 04/12/2020] [Indexed: 05/20/2023]
Abstract
Serine acetyltransferase (SAT) (EC 2.3.1.30) is the rate-limiting enzyme of cysteine (Cys) biosynthesis, providing the decisive precursor for the ubiquitous defense thiol glutathione (GSH). Together with O-acetylserine (thiol) lyase (OAS-TL; EC 2.5.1.47) SAT generates Cys in the cytosol, plastids, and mitochondria of vascular plants. The current study aimed to overproduce Cys and GSH for enhanced stress tolerance via overexpression of the feedback-insensitive isoform of serine acetyltransferase from tobacco, i.e., NtSAT4. Constitutive overexpression of NtSAT4 in Brassica napus resulted in the 2.6-fold-4-fold higher SAT activity in different subcellular compartment-specific lines. This higher SAT activity led to a 2.5-fold-3.5-fold higher steady-state level of free Cys and 2.2-fold-5.3-fold elevated level of GSH in leaves compared with nontransformed plants. Among the compartment-specific lines, the mitochondrial targeted NtSAT4 overexpressor line M-182 showed the highest levels of Cys (3.5-fold) and GSH (5.3-fold) compared with wild-type plants. Overexpression of NtSAT4 conferred a physiological advantage in terms of enhanced tolerance against oxidative stress with hydrogen peroxide and the heavy metal cadmium (Cd). The NtSAT4 overexpressor lines showed a significantly higher amount of iron (Fe) translocation from roots to shoots compared with nontransformed plants. Overall, these results suggest that overexpression of NtSAT4 is a promising approach to creating plants with tolerance to heavy metals and oxidative stress and, in addition, may potentially improve plant nutrition in terms of enhanced Fe translocation from roots to shoots.
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Affiliation(s)
- Hala Rajab
- Institute of Biotechnology and Genetic Engineering, The University of Agriculture Peshawar, 25130, Peshawar, Pakistan; Centre for Organismal Studies (COS), Heidelberg University, 69120, Heidelberg, Germany
| | - Muhammad Sayyar Khan
- Institute of Biotechnology and Genetic Engineering, The University of Agriculture Peshawar, 25130, Peshawar, Pakistan.
| | - Markus Wirtz
- Centre for Organismal Studies (COS), Heidelberg University, 69120, Heidelberg, Germany
| | - Mario Malagoli
- Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Legnaro, PD, Italy
| | - Fariha Qahar
- Institute of Biotechnology and Genetic Engineering, The University of Agriculture Peshawar, 25130, Peshawar, Pakistan
| | - Rüdiger Hell
- Centre for Organismal Studies (COS), Heidelberg University, 69120, Heidelberg, Germany
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7
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Wang L, Yang W, Song Y, Gu Y, Hu Y. A double-indole structure fluorescent probe for monitoring sulfur dioxide derivatives with distinct ratiometric fluorescence signals in mammalian cells. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 225:117495. [PMID: 31491614 DOI: 10.1016/j.saa.2019.117495] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 08/25/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
Based on the addition reaction of the sulfur dioxide derivative to the CC double bond, the probe HDI was designed and synthesized. The two-channel fluorescent probe HDI changed from orange to colorless and the fluorescence changed from red to blue when the bisulfite was detected. And the probe responds rapidly to bisulfite within 2 min, with high sensitivity and specificity. In addition, the probe can be used to detect the concentration of bisulfite with a low detection limit (80 nM). Cytological experiments have also demonstrated that probe HDI has low cytotoxicity and could be used for ratiometric detection of sulfur dioxide derivatives in living cells.
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Affiliation(s)
- Li Wang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, South Puzhu Road, Nanjing 211816, China
| | - Wenge Yang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, South Puzhu Road, Nanjing 211816, China
| | - Yiyi Song
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, South Puzhu Road, Nanjing 211816, China
| | - Yuanyun Gu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, South Puzhu Road, Nanjing 211816, China
| | - Yonghong Hu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, South Puzhu Road, Nanjing 211816, China.
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Zeng R, Farooq MU, Wang L, Su Y, Zheng T, Ye X, Jia X, Zhu J. Study on Differential Protein Expression in Natural Selenium-Enriched and Non-Selenium-Enriched Rice Based on iTRAQ Quantitative Proteomics. Biomolecules 2019; 9:biom9040130. [PMID: 30935009 PMCID: PMC6523350 DOI: 10.3390/biom9040130] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/18/2019] [Accepted: 03/25/2019] [Indexed: 12/14/2022] Open
Abstract
This work was designated to scrutinize the protein differential expression in natural selenium-enriched and non-selenium-enriched rice using the Isobaric-tags for relative and absolute quantification (iTRAQ) proteomics approach. The extracted proteins were subjected to enzyme digestion, desalting, and identified by iTRAQ coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology. High pH C18 separation analysis was performed, and the data were then analyzed by Protein PilotTM (V4.5) search engine. Protein differential expression was searched out by comparing relatively quantified proteins. The analysis was conducted using gene ontology (GO), cluster of orthologous groups of proteins (COG) and Kyoto encyclopedia of genes and genomes (KEGG) metabolic pathways. A total of 3235 proteins were detected and 3161 proteins were quantified, of which 401 were differential proteins. 208 down-regulated and 193 up-regulated proteins were unveiled. 77 targeted significant differentially expressed proteins were screened out for further analysis, and were classified into 10 categories: oxidoreductases, transferases, isomerases, heat shock proteins, lyases, hydrolases, ligases, synthetases, tubulin, and actin. The results indicated that the anti-stress, anti-oxidation, active oxygen metabolism, carbohydrate and amino acid metabolism of natural selenium-enriched rice was higher than that of non-selenium rice. The activation of the starch synthesis pathway was found to be bounteous in non-selenium-enriched rice. Cysteine synthase (CYS) and methyltransferase (metE) might be the two key proteins that cause amino acid differences. OsAPx02, CatC, riPHGPX, HSP70 and HSP90 might be the key enzymes regulating antioxidant and anti-stress effect differences in two types of rice. This study provides basic information about deviations in protein mechanism and secondary metabolites in selenium-enriched and non-selenium-enriched rice.
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Affiliation(s)
- Rui Zeng
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
- Dujiangyan Agricultural and Rural Bureau, Dujiangyan 611830, Sichuan, China.
| | - Muhammad Umer Farooq
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Li Wang
- Meishan Vocational & Technical College, Meishan 62000, Sichuan, China.
| | - Yang Su
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Tengda Zheng
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Xiaoying Ye
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Xiaomei Jia
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Jianqing Zhu
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
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Tuzet A, Rahantaniaina MS, Noctor G. Analyzing the Function of Catalase and the Ascorbate-Glutathione Pathway in H 2O 2 Processing: Insights from an Experimentally Constrained Kinetic Model. Antioxid Redox Signal 2019; 30:1238-1268. [PMID: 30044135 DOI: 10.1089/ars.2018.7601] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
SIGNIFICANCE Plant stress involves redox signaling linked to reactive oxygen species such as hydrogen peroxide (H2O2), which can be generated at high rates in photosynthetic cells. The systems that process H2O2 include catalase (CAT) and the ascorbate-glutathione pathway, but interactions between them remain unclear. Modeling can aid interpretation and pinpoint areas for investigation. Recent Advances: Based on emerging data and concepts, we introduce a new experimentally constrained kinetic model to analyze interactions between H2O2, CAT, ascorbate, glutathione, and NADPH. The sensitivity points required for accurate simulation of experimental observations are analyzed, and the implications for H2O2-linked redox signaling are discussed. CRITICAL ISSUES We discuss several implications of the modeled results, in particular the following. (i) CAT and ascorbate peroxidase can share the load in H2O2 processing even in optimal conditions. (ii) Intracellular H2O2 concentrations more than the low μM range may rarely occur. (iii) Ascorbate redox turnover is largely independent of glutathione until ascorbate peroxidation exceeds a certain value. (iv) NADPH availability may determine glutathione redox status through its influence on monodehydroascorbate reduction. (v) The sensitivity of glutathione status to oxidative stress emphasizes its potential suitability as a sensor of increased H2O2. FUTURE DIRECTIONS Important future questions include the roles of other antioxidative systems in interacting with CAT and the ascorbate-glutathione pathway as well as the nature and significance of processes that achieve redox exchange between different subcellular compartments. Progress in these areas is likely to be favored by integrating kinetic modeling analyses into experimentally based programs, allowing each approach to inform the other.
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Affiliation(s)
- Andrée Tuzet
- 1 Unité Mixte de Recherche ECOSYS/Pôle BIOCLIMATOLOGIE, INRA-AgroParisTech, Thiverval-Grignon, France
| | - Marie-Sylviane Rahantaniaina
- 1 Unité Mixte de Recherche ECOSYS/Pôle BIOCLIMATOLOGIE, INRA-AgroParisTech, Thiverval-Grignon, France.,2 Institute of Plant Sciences Paris-Saclay (IPS2), UMR 9213/UMR1403, Université Paris-Sud, CNRS, INRA, Université d'Evry, Université Paris-Diderot, Sorbonne Paris-Cité, Orsay, France
| | - Graham Noctor
- 2 Institute of Plant Sciences Paris-Saclay (IPS2), UMR 9213/UMR1403, Université Paris-Sud, CNRS, INRA, Université d'Evry, Université Paris-Diderot, Sorbonne Paris-Cité, Orsay, France
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10
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Hua Y, Wang C, Wang S, Liu Z, Liu X, Zou L, Gu W, Luo Y, Liu J. iTRAQ-Based Quantitative Proteomic Analysis of Pseudostellaria heterophylla from Geo-Authentic Habitat and Cultivated Bases. CURR PROTEOMICS 2019. [DOI: 10.2174/1570164616666181116124050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Pseudostellaria heterophylla is an important tonic traditional Chinese medicine.
However, the molecular changes in the herb from geo-authentic habitat and cultivated bases remain
to be explored.
Objective:
The purpose of this research was to study differences in P. heterophylla from geo-authentic
habitat and cultivated bases.
Methods:
High-throughput technologies of transcriptomic and proteomic were used to identify proteins.
Isobaric Tags for Relative and Absolute Quantification (iTRAQ) MS/MS has been utilized to
evaluate changes in P. heterophylla from geo-authentic habitat and cultivated bases.
Results:
In this study, a total of 3775 proteins were detected, and 140 differentially expressed proteins
were found in P. heterophylla from geo-authentic habitat and cultivated bases. 44 significantly differential
expressed proteins were identified based on functional analysis classified into nine categories.
Five differentially expressed proteins were confirmed at the gene expression level by Quantitative realtime
PCR. Catabolic metabolism, carbohydrate metabolism, and response to stress of oxidoreductases
and transferases in P. heterophylla from geo-authentic habitat were stronger than in those from cultivated
bases, but protein folding and response to stress of heat shock proteins, isomerases, rubisco large
subunit-binding proteins, chaperone proteins, and luminal-binding proteins in herbs from cultivated
bases were more active. ADG1 and TKTA could be the critical proteins to regulate sucrose; MFP2 and
CYS may be the crucial proteins that control the metabolism of fatty acids and amino acids.
Conclusion:
These results will provide the basic information for exploring the differences in secondary
metabolites in P. heterophylla from geo-authentic habitat and cultivated bases and the protein mechanism
of its quality formation.
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Affiliation(s)
- Yujiao Hua
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
| | - Chengcheng Wang
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
| | - Shengnan Wang
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
| | - Zixiu Liu
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
| | - Xunhong Liu
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
| | - Lisi Zou
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
| | - Wei Gu
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
| | - Yiyuan Luo
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
| | - Juanxiu Liu
- School of Pharmacy, Nanjing University of Chinese Medicine, No. 138, Xianlin Road, Nanjing 210023, China
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11
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Cytosolic Cysteine Synthase Switch Cysteine and Mimosine Production in Leucaena leucocephala. Appl Biochem Biotechnol 2018; 186:613-632. [PMID: 29691793 DOI: 10.1007/s12010-018-2745-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 03/21/2018] [Indexed: 10/17/2022]
Abstract
In higher plants, multiple copies of the cysteine synthase gene are present for cysteine biosynthesis. Some of these genes also have the potential to produce various kinds of β-substitute alanine. In the present study, we cloned a 1275-bp cDNA for cytosolic O-acetylserine(thiol)lyase (cysteine synthase) (Cy-OASTL) from Leucaena leucocephala. The purified protein product showed a dual function of cysteine and mimosine synthesis. Kinetics studies showed pH optima of 7.5 and 8.0, while temperature optima of 40 and 35 °C, respectively, for cysteine and mimosine synthesis. The kinetic parameters such as apparent Km, kcat were determined for both cysteine and mimosine synthesis with substrates O-acetylserine (OAS) and Na2S or 3-hydroxy-4-pyridone (3H4P). From the in vitro results with the common substrate OAS, the apparent kcat for Cys production is over sixfold higher than mimosine synthesis and the apparent Km is 3.7 times lower, suggesting Cys synthesis is the favored pathway.
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12
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Yeon JY, Yoo SJ, Takagi H, Kang HA. A Novel Mitochondrial Serine O-Acetyltransferase, OpSAT1, Plays a Critical Role in Sulfur Metabolism in the Thermotolerant Methylotrophic Yeast Ogataea parapolymorpha. Sci Rep 2018; 8:2377. [PMID: 29402922 PMCID: PMC5799214 DOI: 10.1038/s41598-018-20630-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 01/22/2018] [Indexed: 12/03/2022] Open
Abstract
In most bacteria and plants, direct biosynthesis of cysteine from sulfide via O-acetylserine (OAS) is essential to produce sulfur amino acids from inorganic sulfur. Here, we report the functional analysis of a novel mitochondrial serine O-acetyltransferase (SAT), responsible for converting serine into OAS, in the thermotolerant methylotrophic yeast Ogataea parapolymorpha. Domain analysis of O. parapolymorpha SAT (OpSat1p) and other fungal SATs revealed that these proteins possess a mitochondrial targeting sequence (MTS) at the N-terminus and an α/β hydrolase 1 domain at the C-terminal region, which is quite different from the classical SATs of bacteria and plants. Noticeably, OpSat1p is functionally interchangeable with Escherichia coli SAT, CysE, despite that it displays much less enzymatic activity, with marginal feedback inhibition by cysteine, compared to CysE. The Opsat1Δ-null mutant showed remarkably reduced intracellular levels of cysteine and glutathione, implying OAS generation defect. The MTS of OpSat1p directs the mitochondrial targeting of a reporter protein, thus, supporting the localization of OpSat1p in the mitochondria. Intriguingly, the OpSat1p variant lacking MTS restores the OAS auxotrophy, but not the cysteine auxotrophy of the Opsat1Δ mutant strain. This is the first study on a mitochondrial SAT with critical function in sulfur assimilatory metabolism in fungal species.
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Affiliation(s)
- Ji Yoon Yeon
- Department of Life Science, Chung-Ang University, Seoul, 06974, Korea
| | - Su Jin Yoo
- Department of Life Science, Chung-Ang University, Seoul, 06974, Korea
| | - Hiroshi Takagi
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, 630-0192, Japan.
| | - Hyun Ah Kang
- Department of Life Science, Chung-Ang University, Seoul, 06974, Korea.
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13
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Hua Y, Wang S, Liu Z, Liu X, Zou L, Gu W, Hou Y, Ma Y, Luo Y, Liu J. iTRAQ-based quantitative proteomic analysis of cultivated Pseudostellaria heterophylla and its wild-type. J Proteomics 2016; 139:13-25. [DOI: 10.1016/j.jprot.2016.02.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/20/2016] [Accepted: 02/23/2016] [Indexed: 01/24/2023]
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14
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Considine MJ, Foyer CH. Metabolic responses to sulfur dioxide in grapevine (Vitis vinifera L.): photosynthetic tissues and berries. FRONTIERS IN PLANT SCIENCE 2015; 6:60. [PMID: 25750643 PMCID: PMC4335272 DOI: 10.3389/fpls.2015.00060] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 01/22/2015] [Indexed: 05/20/2023]
Abstract
Research on sulfur metabolism in plants has historically been undertaken within the context of industrial pollution. Resolution of the problem of sulfur pollution has led to sulfur deficiency in many soils. Key questions remain concerning how different plant organs deal with reactive and potentially toxic sulfur metabolites. In this review, we discuss sulfur dioxide/sulfite assimilation in grape berries in relation to gene expression and quality traits, features that remain significant to the food industry. We consider the intrinsic metabolism of sulfite and its consequences for fruit biology and postharvest physiology, comparing the different responses in fruit and leaves. We also highlight inconsistencies in what is considered the "ambient" environmental or industrial exposures to SO2. We discuss these findings in relation to the persistent threat to the table grape industry that intergovernmental agencies will revoke the industry's exemption to the worldwide ban on the use of SO2 for preservation of fresh foods. Transcriptome profiling studies on fruit suggest that added value may accrue from effects of SO2 fumigation on the expression of genes encoding components involved in processes that underpin traits related to customer satisfaction, particularly in table grapes, where SO2 fumigation may extend for several months.
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Affiliation(s)
- Michael J. Considine
- School of Plant Biology, and The UWA Institute of Agriculture, University of Western Australia, Crawley, WA, Australia
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, Yorkshire, UK
- Irrigated Agriculture and Diversification, Department of Agriculture and Food Western Australia, South Perth, WA, Australia
| | - Christine H. Foyer
- School of Plant Biology, and The UWA Institute of Agriculture, University of Western Australia, Crawley, WA, Australia
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, Yorkshire, UK
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15
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Rodríguez-Hernández MDC, Moreno DA, Carvajal M, Martínez-Ballesta MDC. Genotype influences sulfur metabolism in broccoli (Brassica oleracea L.) under elevated CO2 and NaCl stress. PLANT & CELL PHYSIOLOGY 2014; 55:2047-2059. [PMID: 25246493 DOI: 10.1093/pcp/pcu130] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Climatic change predicts elevated salinity in soils as well as increased carbon dioxide dioxide [CO2] in the atmosphere. The present study aims to determine the effect of combined salinity and elevated [CO2] on sulfur (S) metabolism and S-derived phytochemicals in green and purple broccoli (cv. Naxos and cv. Viola, respectively). Elevated [CO2] involved the amelioration of salt stress, especially in cv. Viola, where a lower biomass reduction by salinity was accompanied by higher sodium (Na(+)) and chloride (Cl(-)) compartmentation in the vacuole. Moreover, salinity and elevated [CO2] affected the mineral and glucosinolate contents and the activity of biosynthetic enzymes of S-derived compounds and the degradative enzyme of glucosinolate metabolism, myrosinase, as well as the related amino acids and the antioxidant glutathione (GSH). In cv. Naxos, elevated [CO2] may trigger the antioxidant response to saline stress by means of increased GSH concentration. Also, in cv. Naxos, indolic glucosinolates were more influenced by the NaCl×CO2 interaction whereas in cv. Viola the aliphatic glucosinolates were significantly increased by these conditions. Salinity and elevated [CO2] enhanced the S cellular partitioning and metabolism affecting the myrosinase-glucosinolate system.
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Affiliation(s)
- María del Carmen Rodríguez-Hernández
- Department of Plant Nutrition, Centro de Edafologia y Biologia Aplicada del Segura (CEBAS-CSIC), Campus de Espinardo, Edificio 25, E-Murcia, 30100, Spain
| | - Diego A Moreno
- Department of Food Science and Technology, Centro de Edafologia y Biologia Aplicada del Segura (CEBAS-CSIC), Campus de Espinardo, Edificio 25, E-Murcia, 30100, Spain
| | - Micaela Carvajal
- Department of Plant Nutrition, Centro de Edafologia y Biologia Aplicada del Segura (CEBAS-CSIC), Campus de Espinardo, Edificio 25, E-Murcia, 30100, Spain
| | - María del Carmen Martínez-Ballesta
- Department of Plant Nutrition, Centro de Edafologia y Biologia Aplicada del Segura (CEBAS-CSIC), Campus de Espinardo, Edificio 25, E-Murcia, 30100, Spain
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16
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Zechmann B. Compartment-specific importance of glutathione during abiotic and biotic stress. FRONTIERS IN PLANT SCIENCE 2014; 5:566. [PMID: 25368627 PMCID: PMC4202713 DOI: 10.3389/fpls.2014.00566] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 10/01/2014] [Indexed: 05/19/2023]
Abstract
The tripeptide thiol glutathione (γ-L-glutamyl-L-cysteinyl-glycine) is the most important sulfur containing antioxidant in plants and essential for plant defense against abiotic and biotic stress conditions. It is involved in the detoxification of reactive oxygen species (ROS), redox signaling, the modulation of defense gene expression, and the regulation of enzymatic activities. Even though changes in glutathione contents are well documented in plants and its roles in plant defense are well established, still too little is known about its compartment-specific importance during abiotic and biotic stress conditions. Due to technical advances in the visualization of glutathione and the redox state through microscopical methods some progress was made in the last few years in studying the importance of subcellular glutathione contents during stress conditions in plants. This review summarizes the data available on compartment-specific importance of glutathione in the protection against abiotic and biotic stress conditions such as high light stress, exposure to cadmium, drought, and pathogen attack (Pseudomonas, Botrytis, tobacco mosaic virus). The data will be discussed in connection with the subcellular accumulation of ROS during these conditions and glutathione synthesis which are both highly compartment specific (e.g., glutathione synthesis takes place in chloroplasts and the cytosol). Thus this review will reveal the compartment-specific importance of glutathione during abiotic and biotic stress conditions.
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Affiliation(s)
- Bernd Zechmann
- Center for Microscopy and Imaging, Baylor University, Waco, TX, USA
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17
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Gill SS, Anjum NA, Hasanuzzaman M, Gill R, Trivedi DK, Ahmad I, Pereira E, Tuteja N. Glutathione and glutathione reductase: a boon in disguise for plant abiotic stress defense operations. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 70:204-12. [PMID: 23792825 DOI: 10.1016/j.plaphy.2013.05.032] [Citation(s) in RCA: 234] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 05/24/2013] [Indexed: 05/05/2023]
Abstract
Abiotic stresses such as salinity, drought, clilling, heavy metal are the major limiting factors for crop productivity. These stresses induce the overproduction of reactive oxygen species (ROS) which are highly reactive and toxic, which must be minimized to protect the cell from oxidative damage. The cell organelles, particularly chloroplast and mitochondria are the major sites of ROS production in plants where excessive rate of electron flow takes place. Plant cells are well equipped to efficiently scavenge ROS and its reaction products by the coordinated and concerted action of antioxidant machinery constituted by vital enzymatic and non-enzymatic antioxidant components. Glutathione reductase (GR, EC 1.6.4.2) and tripeptide glutathione (GSH, γ-Glutamyl-Cysteinyl-Glycine) are two major components of ascorbate-glutathione (AsA-GSH) pathway which play significant role in protecting cells against ROS and its reaction products-accrued potential anomalies. Both GR and GSH are physiologically linked together where, GR is a NAD(P)H-dependent enzymatic antioxidant and efficiently maintains the reduced pool of GSH - a cellular thiol. The differential modulation of both GR and GSH in plants has been widely implicated for the significance of these two enigmatic antioxidants as major components of plant defense operations. Considering recent informations gained through molecular-genetic studies, the current paper presents an overview of the structure, localization, biosynthesis (for GSH only), discusses GSH and GR significance in abiotic stress (such as salinity, drought, clilling, heavy metal)-exposed crop plants and also points out unexplored aspects in the current context for future studies.
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Affiliation(s)
- Sarvajeet Singh Gill
- Stress Physiology and Molecular Biology Lab, Centre for Biotechnology, Faculty of Life Sciences, MD University, Rohtak 124 001, India.
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18
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Tahir J, Watanabe M, Jing HC, Hunter DA, Tohge T, Nunes-Nesi A, Brotman Y, Fernie AR, Hoefgen R, Dijkwel PP. Activation of R-mediated innate immunity and disease susceptibility is affected by mutations in a cytosolic O-acetylserine (thiol) lyase in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:118-30. [PMID: 22974487 DOI: 10.1111/tpj.12021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 09/05/2012] [Accepted: 09/10/2012] [Indexed: 05/09/2023]
Abstract
O-acetylserine (thiol) lyases (OASTLs) are evolutionarily conserved proteins among many prokaryotes and eukaryotes that perform sulfur acquisition and synthesis of cysteine. A mutation in the cytosolic OASTL-A1 protein ONSET OF LEAF DEATH3 (OLD3) was previously shown to reduce the OASTL activity of the old3-1 protein in vitro and cause auto-necrosis in specific Arabidopsis accessions. Here we investigated why a mutation in this protein causes auto-necrosis in some but not other accessions. The auto-necrosis was found to depend on Recognition of Peronospora Parasitica 1 (RPP1)-like disease resistance R gene(s) from an evolutionarily divergent R gene cluster that is present in Ler-0 but not the reference accession Col-0. RPP1-like gene(s) show a negative epistatic interaction with the old3-1 mutation that is not linked to reduced cysteine biosynthesis. Metabolic profiling and transcriptional analysis further indicate that an effector triggered-like immune response and metabolic disorder are associated with auto-necrosis in old3-1 mutants, probably activated by an RPP1-like gene. However, the old3-1 protein in itself results in largely neutral changes in primary plant metabolism, stress defence and immune responses. Finally, we showed that lack of a functional OASTL-A1 results in enhanced disease susceptibility against infection with virulent and non-virulent Pseudomonas syringae pv. tomato DC3000 strains. These results reveal an interaction between the cytosolic OASTL and components of plant immunity.
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Affiliation(s)
- Jibran Tahir
- Institute of Molecular BioSciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - Mutsumi Watanabe
- Max-Planck-Institut fuer Molekulare Pflanzenphysiologie, Wissenschaftspark Golm, Am Muehlenberg 1, Potsdam-Golm, 14476, Germany
| | - Hai-Chun Jing
- Centre for Bioenergy Plants Research and Development, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China, and
| | - Donald A Hunter
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand
| | - Takayuki Tohge
- Max-Planck-Institut fuer Molekulare Pflanzenphysiologie, Wissenschaftspark Golm, Am Muehlenberg 1, Potsdam-Golm, 14476, Germany
| | - Adriano Nunes-Nesi
- Max-Planck-Institut fuer Molekulare Pflanzenphysiologie, Wissenschaftspark Golm, Am Muehlenberg 1, Potsdam-Golm, 14476, Germany
| | - Yariv Brotman
- Max-Planck-Institut fuer Molekulare Pflanzenphysiologie, Wissenschaftspark Golm, Am Muehlenberg 1, Potsdam-Golm, 14476, Germany
| | - Alisdair R Fernie
- Max-Planck-Institut fuer Molekulare Pflanzenphysiologie, Wissenschaftspark Golm, Am Muehlenberg 1, Potsdam-Golm, 14476, Germany
| | - Rainer Hoefgen
- Max-Planck-Institut fuer Molekulare Pflanzenphysiologie, Wissenschaftspark Golm, Am Muehlenberg 1, Potsdam-Golm, 14476, Germany
| | - Paul P Dijkwel
- Institute of Molecular BioSciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
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19
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García-Giménez JL, Markovic J, Dasí F, Queval G, Schnaubelt D, Foyer CH, Pallardó FV. Nuclear glutathione. Biochim Biophys Acta Gen Subj 2012; 1830:3304-16. [PMID: 23069719 DOI: 10.1016/j.bbagen.2012.10.005] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/21/2012] [Accepted: 10/08/2012] [Indexed: 12/24/2022]
Abstract
Glutathione (GSH) is a linchpin of cellular defences in plants and animals with physiologically-important roles in the protection of cells from biotic and abiotic stresses. Moreover, glutathione participates in numerous metabolic and cell signalling processes including protein synthesis and amino acid transport, DNA repair and the control of cell division and cell suicide programmes. While it is has long been appreciated that cellular glutathione homeostasis is regulated by factors such as synthesis, degradation, transport, and redox turnover, relatively little attention has been paid to the influence of the intracellular partitioning on glutathione and its implications for the regulation of cell functions and signalling. We focus here on the functions of glutathione in the nucleus, particularly in relation to physiological processes such as the cell cycle and cell death. The sequestration of GSH in the nucleus of proliferating animal and plant cells suggests that common redox mechanisms exist for DNA regulation in G1 and mitosis in all eukaryotes. We propose that glutathione acts as "redox sensor" at the onset of DNA synthesis with roles in maintaining the nuclear architecture by providing the appropriate redox environment for the DNA replication and safeguarding DNA integrity. In addition, nuclear GSH may be involved in epigenetic phenomena and in the control of nuclear protein degradation by nuclear proteasome. Moreover, by increasing the nuclear GSH pool and reducing disulfide bonds on nuclear proteins at the onset of cell proliferation, an appropriate redox environment is generated for the stimulation of chromatin decompaction. This article is part of a Special Issue entitled Cellular functions of glutathione.
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20
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Noctor G, Mhamdi A, Chaouch S, Han Y, Neukermans J, Marquez-Garcia B, Queval G, Foyer CH. Glutathione in plants: an integrated overview. PLANT, CELL & ENVIRONMENT 2012; 35:454-84. [PMID: 21777251 DOI: 10.1111/j.1365-3040.2011.02400.x] [Citation(s) in RCA: 784] [Impact Index Per Article: 65.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plants cannot survive without glutathione (γ-glutamylcysteinylglycine) or γ-glutamylcysteine-containing homologues. The reasons why this small molecule is indispensable are not fully understood, but it can be inferred that glutathione has functions in plant development that cannot be performed by other thiols or antioxidants. The known functions of glutathione include roles in biosynthetic pathways, detoxification, antioxidant biochemistry and redox homeostasis. Glutathione can interact in multiple ways with proteins through thiol-disulphide exchange and related processes. Its strategic position between oxidants such as reactive oxygen species and cellular reductants makes the glutathione system perfectly configured for signalling functions. Recent years have witnessed considerable progress in understanding glutathione synthesis, degradation and transport, particularly in relation to cellular redox homeostasis and related signalling under optimal and stress conditions. Here we outline the key recent advances and discuss how alterations in glutathione status, such as those observed during stress, may participate in signal transduction cascades. The discussion highlights some of the issues surrounding the regulation of glutathione contents, the control of glutathione redox potential, and how the functions of glutathione and other thiols are integrated to fine-tune photorespiratory and respiratory metabolism and to modulate phytohormone signalling pathways through appropriate modification of sensitive protein cysteine residues.
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Affiliation(s)
- Graham Noctor
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, Orsay cedex, France.
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21
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Kim WS, Chronis D, Juergens M, Schroeder AC, Hyun SW, Jez JM, Krishnan HB. Transgenic soybean plants overexpressing O-acetylserine sulfhydrylase accumulate enhanced levels of cysteine and Bowman-Birk protease inhibitor in seeds. PLANTA 2012; 235:13-23. [PMID: 21805150 DOI: 10.1007/s00425-011-1487-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 07/07/2011] [Indexed: 05/08/2023]
Abstract
Soybeans provide an excellent source of protein in animal feed. Soybean protein quality can be enhanced by increasing the concentration of sulfur-containing amino acids. Previous attempts to increase the concentration of sulfur-containing amino acids through the expression of heterologous proteins have met with limited success. Here, we report a successful strategy to increase the cysteine content of soybean seed through the overexpression of a key sulfur assimilatory enzyme. We have generated several transgenic soybean plants that overexpress a cytosolic isoform of O-acetylserine sulfhydrylase (OASS). These transgenic soybean plants exhibit a four- to tenfold increase in OASS activity when compared with non-transformed wild-type. The OASS activity in the transgenic soybeans was significantly higher at all the stages of seed development. Unlike the non-transformed soybean plants, there was no marked decrease in the OASS activity even at later stages of seed development. Overexpression of cytosolic OASS resulted in a 58-74% increase in protein-bound cysteine levels compared with non-transformed wild-type soybean seeds. A 22-32% increase in the free cysteine levels was also observed in transgenic soybeans overexpressing OASS. Furthermore, these transgenic soybean plants showed a marked increase in the accumulation of Bowman-Birk protease inhibitor, a cysteine-rich protein. The overall increase in soybean total cysteine content (both free and protein-bound) satisfies the recommended levels required for the optimal growth of monogastric animals.
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Affiliation(s)
- Won-Seok Kim
- Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA
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22
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Koffler BE, Maier R, Zechmann B. Subcellular distribution of glutathione precursors in Arabidopsis thaliana. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2011; 53:930-41. [PMID: 22050910 PMCID: PMC3588602 DOI: 10.1111/j.1744-7909.2011.01085.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Glutathione is an important antioxidant and has many important functions in plant development, growth and defense. Glutathione synthesis and degradation is highly compartment-specific and relies on the subcellular availability of its precursors, cysteine, glutamate, glycine and γ-glutamylcysteine especially in plastids and the cytosol which are considered as the main centers for glutathione synthesis. The availability of glutathione precursors within these cell compartments is therefore of great importance for successful plant development and defense. The aim of this study was to investigate the compartment-specific importance of glutathione precursors in Arabidopsis thaliana. The subcellular distribution was compared between wild type plants (Col-0), plants with impaired glutathione synthesis (glutathione deficient pad2-1 mutant, wild type plants treated with buthionine sulfoximine), and one complemented line (OE3) with restored glutathione synthesis. Immunocytohistochemistry revealed that the inhibition of glutathione synthesis induced the accumulation of the glutathione precursors cysteine, glutamate and glycine in most cell compartments including plastids and the cytosol. A strong decrease could be observed in γ-glutamylcysteine (γ-EC) contents in these cell compartments. These experiments demonstrated that the inhibition of γ-glutamylcysteine synthetase (GSH1) - the first enzyme of glutathione synthesis - causes a reduction of γ-EC levels and an accumulation of all other glutathione precursors within the cells.
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23
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Na G, Salt DE. Differential regulation of serine acetyltransferase is involved in nickel hyperaccumulation in Thlaspi goesingense. J Biol Chem 2011; 286:40423-32. [PMID: 21930704 PMCID: PMC3220491 DOI: 10.1074/jbc.m111.247411] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 09/02/2011] [Indexed: 11/06/2022] Open
Abstract
When growing in its native habitat, Thlaspi goesingense can hyperaccumulate 1.2% of its shoot dry weight as nickel. We reported previously that both constitutively elevated activity of serine acetyltransferase (SAT) and concentration of glutathione (GSH) are involved in the ability of T. goesingense to tolerate nickel. A feature of SAT is its feedback inhibition by L-cysteine. To understand the role of this regulation of SAT by Cys on GSH-mediated nickel tolerance in T. goesingense, we characterized the enzymatic properties of SATs from T. goesingense. We demonstrate that all three isoforms of SAT in T. goesingense are insensitive to inhibition by Cys. Further, two amino acids (proline and alanine) in the C-terminal region of the cytosolic SAT (SAT-c) from T. goesingense are responsible for converting the enzyme from a Cys-sensitive to a Cys-insensitive form. Furthermore, the Cys-insensitive isoform of SAT-c confers elevated resistance to nickel when expressed in Escherichia coli and Arabidopsis thaliana, supporting a role for altered regulation of SAT by Cys in nickel tolerance in T. goesingense.
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Affiliation(s)
- GunNam Na
- From the Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907
| | - David E. Salt
- From the Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907
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24
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Noctor G, Queval G, Mhamdi A, Chaouch S, Foyer CH. Glutathione. THE ARABIDOPSIS BOOK 2011; 9:e0142. [PMID: 22303267 PMCID: PMC3267239 DOI: 10.1199/tab.0142] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Glutathione is a simple sulfur compound composed of three amino acids and the major non-protein thiol in many organisms, including plants. The functions of glutathione are manifold but notably include redox-homeostatic buffering. Glutathione status is modulated by oxidants as well as by nutritional and other factors, and can influence protein structure and activity through changes in thiol-disulfide balance. For these reasons, glutathione is a transducer that integrates environmental information into the cellular network. While the mechanistic details of this function remain to be fully elucidated, accumulating evidence points to important roles for glutathione and glutathione-dependent proteins in phytohormone signaling and in defense against biotic stress. Work in Arabidopsis is beginning to identify the processes that govern glutathione status and that link it to signaling pathways. As well as providing an overview of the components that regulate glutathione homeostasis (synthesis, degradation, transport, and redox turnover), the present discussion considers the roles of this metabolite in physiological processes such as light signaling, cell death, and defense against microbial pathogen and herbivores.
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Affiliation(s)
- Graham Noctor
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, 91405 Orsay cedex, France
| | - Guillaume Queval
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, 91405 Orsay cedex, France
- Present address: Department of Plant Systems Biology, Flanders Institute for Biotechnology and Department of Plant Biotechnologyand Genetics, Gent University, 9052 Gent, Belgium
| | - Amna Mhamdi
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, 91405 Orsay cedex, France
| | - Sejir Chaouch
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, 91405 Orsay cedex, France
| | - Christine H. Foyer
- Centre for Plant Sciences, Faculty of Biology, University of Leeds, Leeds, LS2 9JT, UK
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25
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Shibagaki N, Grossman AR. Binding of cysteine synthase to the STAS domain of sulfate transporter and its regulatory consequences. J Biol Chem 2010; 285:25094-102. [PMID: 20529854 DOI: 10.1074/jbc.m110.126888] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sulfate ion (SO(4)(2-)) is transported into plant root cells by SO(4)(2-) transporters and then mostly reduced to sulfide (S(2-)). The S(2-) is then bonded to O-acetylserine through the activity of cysteine synthase (O-acetylserine (thiol)lyase or OASTL) to form cysteine, the first organic molecule of the SO(4)(2-) assimilation pathway. Here, we show that a root plasma membrane SO(4)(2-) transporter of Arabidopsis, SULTR1;2, physically interacts with OASTL. The interaction was initially demonstrated using a yeast two-hybrid system and corroborated by both in vivo and in vitro binding assays. The domain of SULTR1;2 shown to be important for association with OASTL is called the STAS domain. This domain is at the C terminus of the transporter and extends from the plasma membrane into the cytoplasm. The functional relevance of the OASTL-STAS interaction was investigated using yeast mutant cells devoid of endogenous SO(4)(2-) uptake activity but co-expressing SULTR1;2 and OASTL. The analysis of SO(4)(2-) transport in these cells suggests that the binding of OASTL to the STAS domain in this heterologous system negatively impacts transporter activity. In contrast, the activity of purified OASTL measured in vitro was enhanced by co-incubation with the STAS domain of SULTR1;2 but not with the analogous domain of the SO(4)(2-) transporter isoform SULTR1;1, even though the SULTR1;1 STAS peptide also interacts with OASTL based on the yeast two-hybrid system and in vitro binding assays. These observations suggest a regulatory model in which interactions between SULTR1;2 and OASTL coordinate internalization of SO(4)(2-) with the energetic/metabolic state of plant root cells.
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Affiliation(s)
- Nakako Shibagaki
- Department of Plant Biology, The Carnegie Institution for Science, Stanford, California 94305, USA.
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Tabe L, Wirtz M, Molvig L, Droux M, Hell R. Overexpression of serine acetlytransferase produced large increases in O-acetylserine and free cysteine in developing seeds of a grain legume. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:721-33. [PMID: 19939888 PMCID: PMC2814105 DOI: 10.1093/jxb/erp338] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 10/06/2009] [Accepted: 10/26/2009] [Indexed: 05/18/2023]
Abstract
There have been many attempts to increase concentrations of the nutritionally essential sulphur amino acids by modifying their biosynthetic pathway in leaves of transgenic plants. This report describes the first modification of cysteine biosynthesis in developing seeds; those of the grain legume, narrow leaf lupin (Lupinus angustifolius, L.). Expression in developing lupin embryos of a serine acetyltransferase (SAT) from Arabidopsis thaliana (AtSAT1 or AtSerat 2;1) was associated with increases of up to 5-fold in the concentrations of O-acetylserine (OAS), the immediate product of SAT, and up to 26-fold in free cysteine, resulting in some of the highest in vivo concentrations of these metabolites yet reported. Despite the dramatic changes in free cysteine in developing embryos of SAT overexpressers, concentrations of free methionine in developing embryos, and the total cysteine and methionine concentrations in mature seeds were not significantly altered. Pooled F(2) seeds segregating for the SAT transgene and for a transgene encoding a methionine- and cysteine-rich sunflower seed storage protein also had increased OAS and free cysteine, but not free methionine, during development, and no increase in mature seed total sulphur amino acids compared with controls lacking SAT overexpression. The data support the view that the cysteine biosynthetic pathway is active in developing seeds, and indicate that SAT activity limits cysteine biosynthesis, but that cysteine supply is not limiting for methionine biosynthesis or for storage protein synthesis in maturing lupin embryos in conditions of adequate sulphur nutrition. OAS and free methionine, but not free cysteine, were implicated as signalling metabolites controlling expression of a gene for a cysteine-rich seed storage protein.
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Affiliation(s)
- Linda Tabe
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601 Australia.
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Haas FH, Heeg C, Queiroz R, Bauer A, Wirtz M, Hell R. Mitochondrial serine acetyltransferase functions as a pacemaker of cysteine synthesis in plant cells. PLANT PHYSIOLOGY 2008; 148:1055-67. [PMID: 18753283 PMCID: PMC2556817 DOI: 10.1104/pp.108.125237] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 08/25/2008] [Indexed: 05/20/2023]
Abstract
Cysteine (Cys) synthesis in plants is carried out by two sequential reactions catalyzed by the rate-limiting enzyme serine acetyltransferase (SAT) and excess amounts of O-acetylserine(thiol)lyase. Why these reactions occur in plastids, mitochondria, and cytosol of plants remained unclear. Expression of artificial microRNA (amiRNA) against Sat3 encoding mitochondrial SAT3 in transgenic Arabidopsis (Arabidopsis thaliana) plants demonstrates that mitochondria are the most important compartment for the synthesis of O-acetylserine (OAS), the precursor of Cys. Reduction of RNA levels, protein contents, SAT enzymatic activity, and phenotype strongly correlate in independent amiSAT3 lines and cause significantly retarded growth. The expression of the other four Sat genes in the Arabidopsis genome are not affected by amiRNA-SAT3 according to quantitative real-time polymerase chain reaction and microarray analyses. Application of radiolabeled serine to leaf pieces revealed severely reduced incorporation rates into Cys and even more so into glutathione. Accordingly, steady-state levels of OAS are 4-fold reduced. Decrease of sulfate reduction-related genes is accompanied by an accumulation of sulfate in amiSAT3 lines. These results unequivocally show that mitochondria provide the bulk of OAS in the plant cell and are the likely site of flux regulation. Together with recent data, the cytosol appears to be a major site of Cys synthesis, while plastids contribute reduced sulfur as sulfide. Thus, Cys synthesis in plants is significantly different from that in nonphotosynthetic eukaryotes at the cellular level.
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Affiliation(s)
- Florian H Haas
- Heidelberg Institute for Plant Sciences, Heidelberg University, Heidelberg, Germany
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28
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Watanabe M, Mochida K, Kato T, Tabata S, Yoshimoto N, Noji M, Saito K. Comparative genomics and reverse genetics analysis reveal indispensable functions of the serine acetyltransferase gene family in Arabidopsis. THE PLANT CELL 2008; 20:2484-96. [PMID: 18776059 PMCID: PMC2570737 DOI: 10.1105/tpc.108.060335] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 08/07/2008] [Accepted: 08/18/2008] [Indexed: 05/19/2023]
Abstract
Ser acetyltransferase (SERAT), which catalyzes O-acetyl-Ser (OAS) formation, plays a key role in sulfur assimilation and Cys synthesis. Despite several studies on SERATs from various plant species, the in vivo function of multiple SERAT genes in plant cells remains unaddressed. Comparative genomics studies with the five genes of the SERAT gene family in Arabidopsis thaliana indicated that all three Arabidopsis SERAT subfamilies are conserved across five plant species with available genome sequences. Single and multiple knockout mutants of all Arabidopsis SERAT gene family members were analyzed. All five quadruple mutants with a single gene survived, with three mutants showing dwarfism. However, the quintuple mutant lacking all SERAT genes was embryo-lethal. Thus, all five isoforms show functional redundancy in vivo. The developmental and compartment-specific roles of each SERAT isoform were also demonstrated. Mitochondrial SERAT2;2 plays a predominant role in cellular OAS formation, while plastidic SERAT2;1 contributes less to OAS formation and subsequent Cys synthesis. Three cytosolic isoforms, SERAT1;1, SERAT3;1, and SERAT3;2, may play a major role during seed development. Thus, the evolutionally conserved SERAT gene family is essential in cellular processes, and the substrates and products of SERAT must be exchangeable between the cytosol and organelles.
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Affiliation(s)
- Mutsumi Watanabe
- Graduate School of Pharmaceutical Sciences, Chiba University, Inage-ku, Chiba 263-8522, Japan
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29
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Stiller I, Dancs G. Increasing the nutritive value of potato by metabolic engineering of cysteine content. ACTA ALIMENTARIA 2008. [DOI: 10.1556/aalim.2007.0021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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30
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Hell R, Wirtz M. Metabolism of Cysteine in Plants and Phototrophic Bacteria. SULFUR METABOLISM IN PHOTOTROPHIC ORGANISMS 2008. [DOI: 10.1007/978-1-4020-6863-8_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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31
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Watanabe M, Kusano M, Oikawa A, Fukushima A, Noji M, Saito K. Physiological roles of the beta-substituted alanine synthase gene family in Arabidopsis. PLANT PHYSIOLOGY 2008; 146:310-20. [PMID: 18024555 PMCID: PMC2230570 DOI: 10.1104/pp.107.106831] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 11/02/2007] [Indexed: 05/18/2023]
Abstract
The beta-substituted alanine (Ala) synthase (Bsas) family in the large superfamily of pyridoxal 5'-phosphate-dependent enzymes comprises cysteine (Cys) synthase (CSase) [O-acetyl-serine (thiol) lyase] and beta-cyano-Ala synthase (CASase) in plants. Nine genomic sequences encode putative Bsas proteins in Arabidopsis thaliana. The physiological roles of these Bsas isoforms in vivo were investigated by the characterization of T-DNA insertion mutants. Analyses of gene expression, activities of CSase and CASase, and levels of Cys and glutathione in the bsas mutants indicated that cytosolic Bsas1;1, plastidic Bsas2;1, and mitochondrial Bsas2;2 play major roles in Cys biosynthesis. Cytosolic Bsas1;1 has the most dominant contribution both in leaf and root, and mitochondrial Bsas2;2 plays a significant role in root. Mitochondrial Bsas3;1 is a genuine CASase. Nontargeted metabolome analyses of knockout mutants were carried out by a combination of gas chromatography time-of-flight mass spectrometry and capillary electrophoresis time-of-flight mass spectrometry. The level of gamma-glutamyl-beta-cyano-Ala decreased in the mutant bsas3;1, indicating the crucial role of Bsas3;1 in beta-cyano-Ala metabolism in vivo.
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Affiliation(s)
- Mutsumi Watanabe
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
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32
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Wirtz M, Hell R. Dominant-negative modification reveals the regulatory function of the multimeric cysteine synthase protein complex in transgenic tobacco. THE PLANT CELL 2007; 19:625-39. [PMID: 17293569 PMCID: PMC1867341 DOI: 10.1105/tpc.106.043125] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 12/21/2006] [Accepted: 01/23/2007] [Indexed: 05/13/2023]
Abstract
Cys synthesis in plants constitutes the entry of reduced sulfur from assimilatory sulfate reduction into metabolism. The catalyzing enzymes serine acetyltransferase (SAT) and O-acetylserine (OAS) thiol lyase (OAS-TL) reversibly form the heterooligomeric Cys synthase complex (CSC). Dominant-negative mutation of the CSC showed the crucial function for the regulation of Cys biosynthesis in vivo. An Arabidopsis thaliana SAT was overexpressed in the cytosol of transgenic tobacco (Nicotiana tabacum) plants in either enzymatically active or inactive forms that were both shown to interact efficiently with endogenous tobacco OAS-TL proteins. Active SAT expression resulted in a 40-fold increase in SAT activity and strong increases in the reaction intermediate OAS as well as Cys, glutathione, Met, and total sulfur contents. However, inactive SAT expression produced much greater enhancing effects, including 30-fold increased Cys levels, attributable, apparently, to the competition of inactive transgenic SAT with endogenous tobacco SAT for binding to OAS-TL. Expression levels of tobacco SAT and OAS-TL remained unaffected. Flux control coefficients suggested that the accumulation of OAS and Cys in both types of transgenic plants was accomplished by different mechanisms. These data provide evidence that the CSC and its subcellular compartmentation play a crucial role in the control of Cys biosynthesis, a unique function for a plant metabolic protein complex.
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Affiliation(s)
- Markus Wirtz
- Heidelberg Institute of Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
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33
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Ali V, Nozaki T. Current therapeutics, their problems, and sulfur-containing-amino-acid metabolism as a novel target against infections by "amitochondriate" protozoan parasites. Clin Microbiol Rev 2007; 20:164-87. [PMID: 17223627 PMCID: PMC1797636 DOI: 10.1128/cmr.00019-06] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The "amitochondriate" protozoan parasites of humans Entamoeba histolytica, Giardia intestinalis, and Trichomonas vaginalis share many biochemical features, e.g., energy and amino acid metabolism, a spectrum of drugs for their treatment, and the occurrence of drug resistance. These parasites possess metabolic pathways that are divergent from those of their mammalian hosts and are often considered to be good targets for drug development. Sulfur-containing-amino-acid metabolism represents one such divergent metabolic pathway, namely, the cysteine biosynthetic pathway and methionine gamma-lyase-mediated catabolism of sulfur-containing amino acids, which are present in T. vaginalis and E. histolytica but absent in G. intestinalis. These pathways are potentially exploitable for development of drugs against amoebiasis and trichomoniasis. For instance, L-trifluoromethionine, which is catalyzed by methionine gamma-lyase and produces a toxic product, is effective against T. vaginalis and E. histolytica parasites in vitro and in vivo and may represent a good lead compound. In this review, we summarize the biology of these microaerophilic parasites, their clinical manifestation and epidemiology of disease, chemotherapeutics, the modes of action of representative drugs, and problems related to these drugs, including drug resistance. We further discuss our approach to exploit unique sulfur-containing-amino-acid metabolism, focusing on development of drugs against E. histolytica.
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Affiliation(s)
- Vahab Ali
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
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Liu F, Yoo BC, Lee JY, Pan W, Harmon AC. Calcium-regulated phosphorylation of soybean serine acetyltransferase in response to oxidative stress. J Biol Chem 2006; 281:27405-15. [PMID: 16854983 DOI: 10.1074/jbc.m604548200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycine max serine acetyltransferase 2;1 (GmSerat2;1) is a member of a family of enzymes that catalyze the first reaction in the biosynthesis of cysteine from serine. It was identified by interaction cloning as a protein that binds to calcium-dependent protein kinase. In vitro phosphorylation assays showed that GmSerat2;1, but not GmSerat2;1 mutants (S378A or S378D), were phosphorylated by soybean calcium-dependent protein kinase isoforms. Recombinant GmSerat2;1 was also phosphorylated by soybean cell extract in a Ca2+-dependent manner. Phosphorylation of recombinant GmSerat2;1 had no effect on its catalytic activity but rendered the enzyme insensitive to the feedback inhibition by cysteine. In transient expression analyses, fluorescently tagged GmSerat2;1 localized in the cytoplasm and with plastids. Phosphorylation state-specific antibodies showed that an increase in GmSerat2;1 phosphorylation occurred in vivo within 5 min of treatment of soybean cells with 0.5 mM hydrogen peroxide, whereas GmSerat2;1 protein synthesis was not significantly induced until 1 h after oxidant challenge. Internal Ca2+ was required in the induction of both GmSerat2;1 phosphorylation and synthesis. Treatment of cells with calcium antagonists showed that externally derived Ca2+ was important for retaining GmSerat2;1 at a basal level of phosphorylation but was not necessary for its hydrogen peroxide-induced synthesis. Protein phosphatase type 1, but not type 2A or alkaline phosphatase, dephosphorylated native GmSerat2;1 in vitro. These results support the hypothesis that GmSerat2;1 is regulated by calcium-dependent protein kinase phosphorylation in vivo and suggest that increased GmSerat2;1 synthesis and phosphorylation in response to active oxygen species could play a role in anti-oxidative stress response.
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Affiliation(s)
- Fenglong Liu
- Program in Plant Molecular and Cellular Biology and the Department of Botany, University of Florida, Gainesville, Florida 32611-8526, USA
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35
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Matityahu I, Kachan L, Bar Ilan I, Amir R. Transgenic tobacco plants overexpressing the Met25 gene of Saccharomyces cerevisiae exhibit enhanced levels of cysteine and glutathione and increased tolerance to oxidative stress. Amino Acids 2006; 30:185-94. [PMID: 16193226 DOI: 10.1007/s00726-005-0250-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2004] [Accepted: 05/23/2005] [Indexed: 10/25/2022]
Abstract
The cysteine biosynthesis pathway differs between plants and the yeast Saccharomyces cerevisiae. The yeast MET25 gene encoded to O-acetylhomoserine sulfhydrylase (AHS) catalyzed the reaction that form homocysteine, which later can be converted into cystiene. In vitro studies show that this enzyme possesses also the activity of O-acetyl(thiol)lyase (OASTL) that catalyzes synthesis of cysteine in plants. In this study, we generated transgenic tobacco plants expressing the yeast MET25 gene under the control of a constitutive promoter and targeted the yeast protein to the cytosol or to the chloroplasts. Both sets of transgenic plants were taller and greener than wild-type plants. Addition of SO(2), the substrate of the yeast enzyme caused a significant elevation of the glutathione content in representative plants from each of the two sets of transgenic plants expressing the yeast gene. Determination of non-protein thiol content indicated up to four-folds higher cysteine and 2.5-fold glutathione levels in these plants. In addition, the leaf discs of the transgenic plants were more tolerant to toxic levels of sulphite, and to paraquat, an herbicide generating active oxygen species.
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Affiliation(s)
- I Matityahu
- Plant Science Laboratory, Migal -- Galilee Technology Center, Kiryat Shmona, Israel
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36
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Wirtz M, Hell R. Functional analysis of the cysteine synthase protein complex from plants: structural, biochemical and regulatory properties. JOURNAL OF PLANT PHYSIOLOGY 2006; 163:273-86. [PMID: 16386330 DOI: 10.1016/j.jplph.2005.11.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 11/29/2005] [Accepted: 11/30/2005] [Indexed: 05/05/2023]
Abstract
Cysteine synthesis in plants represents the final step of assimilatory sulfate reduction and the almost exclusive entry reaction of reduced sulfur into metabolism not only of plants, but also the human food chain in general. It is accomplished by the sequential reaction of two enzymes, serine acetyltransferase (SAT) and O-acetylserine (thiol) lyase (OAS-TL). Together they form the hetero-oligomeric cysteine synthase complex (CSC). Recent evidence is reviewed that identifies the dual function of the CSC as a sensor and as part of a regulatory circuit that controls cellular sulfur homeostasis. Computational modeling of three-dimensional structures of plant SAT and OAS-TL based on the crystal structure of the corresponding bacterial enzymes supports quaternary conformations of SAT as a dimer of trimers and OAS-TL as a homodimer. These findings suggest an overall alpha6beta4 structure of the subunits of the plant CSC. Kinetic measurements of CSC dissociation triggered by the reaction intermediate O-acetylserine as well as CSC stabilization by sulfide indicate quantitative reactions that are suited to fine-tune the equilibrium between free and associated CSC subunits. In addition, in vitro data show that SAT requires binding to OAS-TL for full activity, while at the same time bound OAS-TL becomes inactivated. Since OAS concentrations inside cells increase upon sulfate deficiency, whereas sulfide concentrations most likely decrease, these data suggest the dissociation of the CSC in vivo, accompanied by inactivation of SAT and activation of OAS-TL function in their free homo-oligomer states. Biochemical evidence describes this protein-interaction based mechanism as reversible, thus closing the regulatory circuit. The properties of the CSC and its subunits are therefore consistent with models of positive regulation of sulfate uptake and reduction in plants by OAS as well as a demand-driven repression/de-repression by a sulfur intermediate, such as sulfide.
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Affiliation(s)
- Markus Wirtz
- Heidelberg Institute of Plant Sciences (HIP), University of Heidelberg, Im Neuenheimer Feld 360, 69120 Heidelberg, Germany
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37
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Sors TG, Ellis DR, Salt DE. Selenium uptake, translocation, assimilation and metabolic fate in plants. PHOTOSYNTHESIS RESEARCH 2005; 86:373-89. [PMID: 16307305 DOI: 10.1007/s11120-005-5222-9] [Citation(s) in RCA: 300] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Accepted: 04/10/2005] [Indexed: 05/02/2023]
Abstract
The chemical and physical resemblance between selenium (Se) and sulfur (S) establishes that both these elements share common metabolic pathways in plants. The presence of isologous Se and S compounds indicates that these elements compete in biochemical processes that affect uptake, translocation and assimilation throughout plant development. Yet, minor but crucial differences in reactivity and other metabolic interactions infer that some biochemical processes involving Se may be excluded from those relating to S. This review examines the current understanding of physiological and biochemical relationships between S and Se metabolism by highlighting their similarities and differences in relation to uptake, transport and assimilation pathways as observed in Se hyperaccumulator and non-accumulator plant species. The exploitation of genetic resources used in bioengineering strategies of plants is illuminating the function of sulfate transporters and key enzymes of the S assimilatory pathway in relation to Se accumulation and final metabolic fate. These strategies are providing the basic framework by which to resolve questions relating to the essentiality of Se in plants and the mechanisms utilized by Se hyperaccumulators to circumvent toxicity. In addition, such approaches may assist in the future application of genetically engineered Se accumulating plants for environmental renewal and human health objectives.
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Affiliation(s)
- T G Sors
- Horticulture and Landscape Architecture, Center for Plant Environmental Stress Physiology, Purdue University, 1165 Horticulture Building, West Lafayette, IN 47907, USA
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Wirtz M, Droux M. Synthesis of the sulfur amino acids: cysteine and methionine. PHOTOSYNTHESIS RESEARCH 2005; 86:345-62. [PMID: 16307301 DOI: 10.1007/s11120-005-8810-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Accepted: 06/15/2005] [Indexed: 05/05/2023]
Abstract
This review will assess new features reported for the molecular and biochemical aspects of cysteine and methionine biosynthesis in Arabidopsis thaliana with regards to early published data from other taxa including crop plants and bacteria (Escherichia coli as a model). By contrast to bacteria and fungi, plant cells present a complex organization, in which the sulfur network takes place in multiple sites. Particularly, the impact of sulfur amino-acid biosynthesis compartmentalization will be addressed in respect to localization of sulfur reduction. To this end, the review will focus on regulation of sulfate reduction by synthesis of cysteine through the cysteine synthase complex and the synthesis of methionine and its derivatives. Finally, regulatory aspects of sulfur amino-acid biosynthesis will be explored with regards to interlacing processes such as photosynthesis, carbon and nitrogen assimilation.
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Affiliation(s)
- Markus Wirtz
- Heidelberg Institute of Plant Sciences (HIP), University of Heidelberg, Im Neuenheimer Feld 360, 69120 Heidelberg, Germany.
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Martin MN, Tarczynski MC, Shen B, Leustek T. The role of 5'-adenylylsulfate reductase in controlling sulfate reduction in plants. PHOTOSYNTHESIS RESEARCH 2005; 86:309-23. [PMID: 16328785 DOI: 10.1007/s11120-005-9006-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Accepted: 06/27/2005] [Indexed: 05/05/2023]
Abstract
Cysteine is the first organic product of sulfate assimilation and as such is the precursor of all molecules containing reduced sulfur including methionine, glutathione, and their many metabolites. In plants, 5'-adenylylsulfate (APS) reductase is hypothesized to be a key regulatory point in sulfate assimilation and reduction. APS reductase catalyzes the two-electron reduction of APS to sulfite using glutathione as an electron donor. This paper reviews the experimental basis for this hypothesis. In addition, the results of an experiment designed to test the hypothesis by bypassing the endogenous APS reductase and its regulatory mechanisms are described. Two different bacterial assimilatory reductases were expressed in transgenic Zea mays, the thioredoxin-dependent APS reductase from Pseudomonas aeruginosa and the thioredoxin-dependent 3'-phosphoadenylylsulfate reductase from Escherichia coli. Each of them was placed under transcriptional control of the ubiquitin promoter and the protein products were targeted to chloroplasts. The leaves of transgenic Z. mays lines showed significant accumulation of reduced organic thiol compounds including cysteine, gamma-glutamylcysteine, and glutathione; and reduced inorganic forms of sulfur including sulfite and thiosulfate. Both bacterial enzymes appeared to be equally capable of deregulating the assimilative sulfate reduction pathway. The reduced sulfur compounds accumulated to such high levels that the transgenic plants showed evidence of toxicity. The results provide additional evidence that APS reductase is a major control point for sulfate reduction in Z. mays.
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Affiliation(s)
- Melinda N Martin
- Department of Plant Biology and Pathology, Biotechnology Center for Agriculture and the Environment, Rutgers University, New Brunswick, NJ 08901-8520, USA
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40
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Mendoza-Cózatl D, Loza-Tavera H, Hernández-Navarro A, Moreno-Sánchez R. Sulfur assimilation and glutathione metabolism under cadmium stress in yeast, protists and plants. FEMS Microbiol Rev 2005; 29:653-71. [PMID: 16102596 DOI: 10.1016/j.femsre.2004.09.004] [Citation(s) in RCA: 243] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Revised: 08/03/2004] [Accepted: 09/17/2004] [Indexed: 11/28/2022] Open
Abstract
Glutathione (gamma-glu-cys-gly; GSH) is usually present at high concentrations in most living cells, being the major reservoir of non-protein reduced sulfur. Because of its unique redox and nucleophilic properties, GSH serves in bio-reductive reactions as an important line of defense against reactive oxygen species, xenobiotics and heavy metals. GSH is synthesized from its constituent amino acids by two ATP-dependent reactions catalyzed by gamma-glutamylcysteine synthetase and glutathione synthetase. In yeast, these enzymes are found in the cytosol, whereas in plants they are located in the cytosol and chloroplast. In protists, their location is not well established. In turn, the sulfur assimilation pathway, which leads to cysteine biosynthesis, involves high and low affinity sulfate transporters, and the enzymes ATP sulfurylase, APS kinase, PAPS reductase or APS reductase, sulfite reductase, serine acetyl transferase, O-acetylserine/O-acetylhomoserine sulfhydrylase and, in some organisms, also cystathionine beta-synthase and cystathionine gamma-lyase. The biochemical and genetic regulation of these pathways is affected by oxidative stress, sulfur deficiency and heavy metal exposure. Cells cope with heavy metal stress using different mechanisms, such as complexation and compartmentation. One of these mechanisms in some yeast, plants and protists is the enhanced synthesis of the heavy metal-chelating molecules GSH and phytochelatins, which are formed from GSH by phytochelatin synthase (PCS) in a heavy metal-dependent reaction; Cd(2+) is the most potent activator of PCS. In this work, we review the biochemical and genetic mechanisms involved in the regulation of sulfate assimilation-reduction and GSH metabolism when yeast, plants and protists are challenged by Cd(2+).
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Affiliation(s)
- David Mendoza-Cózatl
- Departamento de Bioquímica, Instituto Nacional de Cardiología, Juan Badiano 1, Col. Sección XVI Tlalpan, México.
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Sperandio B, Polard P, Ehrlich DS, Renault P, Guédon E. Sulfur amino acid metabolism and its control in Lactococcus lactis IL1403. J Bacteriol 2005; 187:3762-78. [PMID: 15901700 PMCID: PMC1112055 DOI: 10.1128/jb.187.11.3762-3778.2005] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cysteine and methionine availability influences many processes in the cell. In bacteria, transcription of the specific genes involved in the synthesis of these two amino acids is usually regulated by different mechanisms or regulators. Pathways for the synthesis of cysteine and methionine and their interconversion were experimentally determined for Lactococcus lactis, a lactic acid bacterium commonly found in food. A new gene, yhcE, was shown to be involved in methionine recycling to cysteine. Surprisingly, 18 genes, representing almost all genes of these pathways, are under the control of a LysR-type activator, FhuR, also named CmbR. DNA microarray experiments showed that FhuR targets are restricted to this set of 18 genes clustered in seven transcriptional units, while cysteine starvation modifies the transcription level of several other genes potentially involved in oxidoreduction processes. Purified FhuR binds a 13-bp box centered 46 to 53 bp upstream of the transcriptional starts from the seven regulated promoters, while a second box with the same consensus is present upstream of the first binding box, separated by 8 to 10 bp. O-Acetyl serine increases FhuR binding affinity to its binding boxes. The overall view of sulfur amino acid metabolism and its regulation in L. lactis indicates that CysE could be a master enzyme controlling the activity of FhuR by providing its effector, while other controls at the enzymatic level appear to be necessary to compensate the absence of differential regulation of the genes involved in the interconversion of methionine and cysteine and other biosynthesis genes.
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Affiliation(s)
- Brice Sperandio
- Génétique Microbienne, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas cedex, France
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Sors TG, Ellis DR, Na GN, Lahner B, Lee S, Leustek T, Pickering IJ, Salt DE. Analysis of sulfur and selenium assimilation in Astragalus plants with varying capacities to accumulate selenium. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 42:785-97. [PMID: 15941393 DOI: 10.1111/j.1365-313x.2005.02413.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Several Astragalus species have the ability to hyperaccumulate selenium (Se) when growing in their native habitat. Given that the biochemical properties of Se parallel those of sulfur (S), we examined the activity of key S assimilatory enzymes ATP sulfurylase (ATPS), APS reductase (APR), and serine acetyltransferase (SAT), as well as selenocysteine methyltransferase (SMT), in eight Astragalus species with varying abilities to accumulate Se. Se hyperaccumulation was found to positively correlate with shoot accumulation of S-methylcysteine (MeCys) and Se-methylselenocysteine (MeSeCys), in addition to the level of SMT enzymatic activity. However, no correlation was observed between Se hyperaccumulation and ATPS, APR, and SAT activities in shoot tissue. Transgenic Arabidopsis thaliana overexpressing both ATPS and APR had a significant enhancement of selenate reduction as a proportion of total Se, whereas SAT overexpression resulted in only a slight increase in selenate reduction to organic forms. In general, total Se accumulation in shoots was lower in the transgenic plants overexpressing ATPS, PaAPR, and SAT. Root growth was adversely affected by selenate treatment in both ATPS and SAT overexpressors and less so in the PaAPR transgenic plants. Such observations support our conclusions that ATPS and APR are major contributors of selenate reduction in planta. However, Se hyperaccumulation in Astragalus is not driven by an overall increase in the capacity of these enzymes, but rather by either an increased Se flux through the S assimilatory pathway, generated by the biosynthesis of the sink metabolites MeCys or MeSeCys, or through an as yet unidentified Se assimilation pathway.
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Affiliation(s)
- Thomas G Sors
- Center for Plant Environmental Stress Physiology, 1165 Horticulture Building, Purdue University, West Lafayette, IN 47907, USA
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Hopkins L, Parmar S, Błaszczyk A, Hesse H, Hoefgen R, Hawkesford MJ. O-acetylserine and the regulation of expression of genes encoding components for sulfate uptake and assimilation in potato. PLANT PHYSIOLOGY 2005; 138:433-40. [PMID: 15805476 PMCID: PMC1104196 DOI: 10.1104/pp.104.057521] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Revised: 02/04/2005] [Accepted: 02/13/2005] [Indexed: 05/18/2023]
Abstract
cDNAs encoding a high-affinity sulfate transporter and an adenosine 5'-phosphosulfate reductase from potato (Solanum tuberosum L. cv Desiree) have been cloned and used to examine the hypothesis that sulfate uptake and assimilation is transcriptionally regulated and that this is mediated via intracellular O-acetylserine (OAS) pools. Gas chromotography coupled to mass spectrometry was used to quantify OAS and its derivative, N-acetylserine. Treatment with external OAS increased sulfate transporter and adenosine 5'-phosphosulfate reductase gene expression consistent with a model of transcriptional induction by OAS. To investigate this further, the Escherichia coli gene cysE (serine acetyltransferase EC 2.3.1.30), which synthesizes OAS, has been expressed in potato to modify internal metabolite pools. Transgenic lines, with increased cysteine and glutathione pools, particularly in the leaves, had increased sulfate transporter expression in the roots. However, the small increases in the OAS pools were not supportive of the hypothesis that this molecule is the signal of sulfur (S) nutritional status. In addition, although during S starvation the content of S-containing compounds decreased (consistent with derepression as a mechanism of regulation), OAS pools increased only following extended starvation, probably as a consequence of the S starvation. Taken together, expression of these genes may be induced by a demand-driven model, via a signal from the shoots, which is not OAS. Rather, the signal may be the depletion of intermediates of the sulfate assimilation pathway, such as sulfide, in the roots. Finally, sulfate transporter activity did not increase in parallel with transcript and protein abundance, indicating additional posttranslational regulatory mechanisms.
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Affiliation(s)
- Laura Hopkins
- Crop Performance and Improvement Division, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
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Riemenschneider A, Riedel K, Hoefgen R, Papenbrock J, Hesse H. Impact of reduced O-acetylserine(thiol)lyase isoform contents on potato plant metabolism. PLANT PHYSIOLOGY 2005; 137:892-900. [PMID: 15728339 PMCID: PMC1065390 DOI: 10.1104/pp.104.057125] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2004] [Revised: 01/03/2005] [Accepted: 01/03/2005] [Indexed: 05/20/2023]
Abstract
Plant cysteine (Cys) synthesis can occur in three cellular compartments: the chloroplast, cytoplasm, and mitochondrion. Cys formation is catalyzed by the enzyme O-acetylserine(thiol)lyase (OASTL) using O-acetylserine (OAS) and sulfide as substrates. To unravel the function of different isoforms of OASTL in cellular metabolism, a transgenic approach was used to down-regulate specifically the plastidial and cytosolic isoforms in potato (Solanum tuberosum). This approach resulted in decreased RNA, protein, and enzymatic activity levels. Intriguingly, H(2)S-releasing capacity was also reduced in these lines. Unexpectedly, the thiol levels in the transgenic lines were, regardless of the selected OASTL isoform, significantly elevated. Furthermore, levels of metabolites such as serine, OAS, methionine, threonine, isoleucine, and lysine also increased in the investigated transgenic lines. This indicates that higher Cys levels might influence methionine synthesis and subsequently pathway-related amino acids. The increase of serine and OAS points to suboptimal Cys synthesis in transgenic plants. Taking these findings together, it can be assumed that excess OASTL activity regulates not only Cys de novo synthesis but also its homeostasis. A model for the regulation of Cys levels in plants is proposed.
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Johnson CM, Roderick SL, Cook PF. The serine acetyltransferase reaction: acetyl transfer from an acylpantothenyl donor to an alcohol. Arch Biochem Biophys 2005; 433:85-95. [PMID: 15581568 DOI: 10.1016/j.abb.2004.08.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2004] [Revised: 08/09/2004] [Indexed: 10/26/2022]
Abstract
Serine acetyltransferase is a member of the left-handed parallel beta-helix family of enzymes that catalyzes the committed step in the de novo synthesis of l-cysteine in bacteria and plants. The enzyme has an ordered kinetic mechanism with acetyl CoA bound prior to l-serine and O-acetyl-l-serine released prior to CoA. The rate-limiting step along the reaction pathway is the nucleophilic attack of the serine hydroxyl on the thioester of acetyl CoA. Product release contributes to rate-limitation at saturating concentrations of reactants. The reaction is catalyzed by an active site general base with a pK of 7, which accepts a proton from the serine hydroxyl as a tetrahedral intermediate is formed between the reactants, and donates it to the thiol of CoA as the intermediate collapses to give products. This mechanism is likely the same for all O-acyltransferases that catalyze their reaction by direct attack of the alcohol on the acyl donor, using an active-site histidine as the general base. Serine acetyltransferase is regulated by feedback inhibition by the end product l-cysteine, which acts by binding to the serine site in the active site and inducing a conformational change that prevents reactant binding. The enzyme also associates with O-acetylserine sulfhydrylase, the final enzyme in the biosynthetic pathway, which contributes to stabilizing the acetyltransferase.
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Affiliation(s)
- Corey M Johnson
- Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, OK 73019, USA
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Galili G, Amir R, Hoefgen R, Hesse H. Improving the levels of essential amino acids and sulfur metabolites in plants. Biol Chem 2005; 386:817-31. [PMID: 16164407 DOI: 10.1515/bc.2005.097] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractPlants represent the major source of food for humans, either directly or indirectly through their use as livestock feeds. Plant foods are not nutritionally balanced because they contain low proportions of a number of essential metabolites, such as vitamins and amino acids, which humans and a significant proportion of their livestock cannot produce on their own. Among the essential amino acids needed in human diets, Lys, Met, Thr and Trp are considered as the most important because they are present in only low levels in plant foods. In the present review, we discuss approaches to improve the levels of the essential amino acids Lys and Met, as well as of sulfur metabolites, in plants using metabolic engineering approaches. We also focus on specific examples for which a deeper understanding of the regulation of metabolic networks in plants is needed for tailor-made improvements of amino acid metabolism with minimal interference in plant growth and productivity.
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Affiliation(s)
- Gad Galili
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
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Nozaki T, Ali V, Tokoro M. Sulfur-Containing Amino Acid Metabolism in Parasitic Protozoa. ADVANCES IN PARASITOLOGY 2005; 60:1-99. [PMID: 16230102 DOI: 10.1016/s0065-308x(05)60001-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sulfur-containing amino acids play indispensable roles in a wide variety of biological activities including protein synthesis, methylation, and biosynthesis of polyamines and glutathione. Biosynthesis and catabolism of these amino acids need to be carefully regulated to achieve the requirement of the above-mentioned activities and also to eliminate toxicity attributable to the amino acids. Genome-wide analyses of enzymes involved in the metabolic pathways of sulfur-containing amino acids, including transsulfuration, sulfur assimilatory de novo cysteine biosynthesis, methionine cycle, and degradation, using genome databases available from a variety of parasitic protozoa, reveal remarkable diversity between protozoan parasites and their mammalian hosts. Thus, the sulfur-containing amino acid metabolic pathways are a rational target for the development of novel chemotherapeutic and prophylactic agents against diseases caused by protozoan parasites. These pathways also demonstrate notable heterogeneity among parasites, suggesting that the metabolism of sulfur-containing amino acids reflects the diversity of parasitism among parasite species, and probably influences their biology and pathophysiology such as virulence competence and stress defense.
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Affiliation(s)
- Tomoyoshi Nozaki
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
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Sundby C, Härndahl U, Gustavsson N, Ahrman E, Murphy DJ. Conserved methionines in chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1703:191-202. [PMID: 15680227 DOI: 10.1016/j.bbapap.2004.09.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2004] [Revised: 08/24/2004] [Accepted: 09/02/2004] [Indexed: 10/26/2022]
Abstract
Heat shock proteins counteract heat and oxidative stress. In chloroplasts, a small heat shock protein (Hsp21) contains a set of conserved methionines, which date back to early in the emergence of terrestrial plants. Methionines M49, M52, M55, M59, M62, M67 are located on one side of an amphipathic helix, which may fold back over two other conserved methionines (M97 and M101), to form a binding groove lined with methionines, for sequence-independent recognition of peptides with an overall hydrophobic character. The sHsps protect other proteins from aggregation by binding to their hydrophobic surfaces, which become exposed under stress. Data are presented showing that keeping the conserved methionines in Hsp21 in a reduced form is a prerequisite to maintain such binding. The chloroplast generates reactive oxygen species under both stress and unstressed conditions, but this organelle is also a highly reducing cellular compartment. Chloroplasts contain a specialized isoform of the enzyme, peptide methionine sulfoxide reductase, the expression of which is light-induced. Recombinant proteins were used to measure that this reductase can restore Hsp21 methionines after sulfoxidation. This paper also describes how methionine sulfoxidation-reduction can be directly assessed by mass spectrometry, how methionine-to-leucine substitution affects Hsp21, and discusses the possible role for an Hsp21 methionine sulfoxidation-reduction cycle in quenching reactive oxygen species.
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Affiliation(s)
- Cecilia Sundby
- Department of Biochemistry, Center for Chemistry and Chemical Engineering, Lund University, P O Box 124, S-221 00 Lund, Sweden.
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Saito K. Sulfur assimilatory metabolism. The long and smelling road. PLANT PHYSIOLOGY 2004; 136:2443-50. [PMID: 15375200 PMCID: PMC523311 DOI: 10.1104/pp.104.046755] [Citation(s) in RCA: 209] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 06/22/2004] [Accepted: 06/23/2004] [Indexed: 05/18/2023]
Affiliation(s)
- Kazuki Saito
- Graduate School of Pharmaceutical Sciences, Chiba University, Inage-ku, Chiba 263-8522, Japan.
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Hesse H, Nikiforova V, Gakière B, Hoefgen R. Molecular analysis and control of cysteine biosynthesis: integration of nitrogen and sulphur metabolism. JOURNAL OF EXPERIMENTAL BOTANY 2004; 55:1283-92. [PMID: 15133050 DOI: 10.1093/jxb/erh136] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Since cysteine is the first committed molecule in plant metabolism containing both sulphur and nitrogen, the regulation of its biosynthesis is critically important. Cysteine itself is required for the production of an abundance of key metabolites in diverse pathways. Plants alter their metabolism to compensate for sulphur and nitrogen deficiencies as best as they can, but limitations in either nutrient not only curb a plant's ability to synthesize cysteine, but also restrict protein synthesis. Nutrients such as nitrate and sulphate (and carbon) act as signals; they trigger molecular mechanisms that modify biosynthetic pathways and thereby have a profound impact on metabolite fluxes. Cysteine biosynthesis is modified by regulators acting at the site of uptake and throughout the plant system. Recent data point to the existence of nutrient-specific signal transduction pathways that relay information about external and internal nutrient concentrations, resulting in alterations to cysteine biosynthesis. Progress in this field has led to the cloning of genes that play pivotal roles in nutrient-induced changes in cysteine formation.
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Affiliation(s)
- Holger Hesse
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department of Molecular Physiology, Am Muehlenberg 1, D-14476 Golm, Germany.
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