1
|
Raihan MT, Tanaka Y, Ishikawa T. Characterization of chloroplastic thioredoxin dependent glutathione peroxidase like protein in Euglena gracilis: biochemical and functional perspectives. Biosci Biotechnol Biochem 2024; 88:1034-1046. [PMID: 38925644 DOI: 10.1093/bbb/zbae087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 06/15/2024] [Indexed: 06/28/2024]
Abstract
Euglena gracilis, a fascinating organism in the scientific realm, exhibits characteristics of both animals and plants. It maintains redox homeostasis through a variety of enzymatic and non-enzymatic antioxidant molecules. In contrast to mammals, Euglena possesses nonselenocysteine glutathione peroxidase homologues that regulate its intracellular pools of reactive oxygen species. In the present study, a full-length cDNA of chloroplastic EgGPXL-1 was isolated and subjected to biochemical and functional characterization. Recombinant EgGPXL-1 scavenged H2O2 and t-BOOH, utilizing thioredoxin as an electron donor rather than glutathione. Despite its monomeric nature, EgGPXL-1 exhibits allosteric behavior with H2O2 as the electron acceptor and follows typical Michaelis-Menten kinetics with t-BOOH. Suppression of EgGPXL-1 gene expression under normal and high-light conditions did not induce critical situations in E. gracilis, suggesting the involvement of compensatory mechanisms in restoring normal conditions.
Collapse
Affiliation(s)
- Md Topu Raihan
- The United Graduate School of Agricultural Sciences, Tottori University, Tottori, Japan
| | - Yasuhiro Tanaka
- The United Graduate School of Agricultural Sciences, Tottori University, Tottori, Japan
| | - Takahiro Ishikawa
- The United Graduate School of Agricultural Sciences, Tottori University, Tottori, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Shimane, Japan
| |
Collapse
|
2
|
Raihan MT, Ishikawa T. Biochemical and Functional Profiling of Thioredoxin-Dependent Cytosolic GPX-like Proteins in Euglena gracilis. Biomolecules 2024; 14:765. [PMID: 39062479 PMCID: PMC11275057 DOI: 10.3390/biom14070765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 06/11/2024] [Accepted: 06/12/2024] [Indexed: 07/28/2024] Open
Abstract
Unlike plants and animals, the phytoflagellate Euglena gracilis lacks catalase and contains a non-selenocysteine glutathione peroxidase-like protein (EgGPXL), two peroxiredoxins (EgPrx1 and EgPrx4), and one ascorbate peroxidase in the cytosol to maintain reactive oxygen species (ROS) homeostasis. In the present study, the full-length cDNA of three cytosolic EgGPXLs was obtained and further characterized biochemically and functionally. These EgGPXLs used thioredoxin instead of glutathione as an electron donor to reduce the levels of H2O2 and t-BOOH. The specific peroxidase activities of these enzymes for H2O2 and t-BOOH were 1.3 to 4.9 and 0.79 to 3.5 µmol/min/mg protein, respectively. Cytosolic EgGPXLs and EgPrx1/EgPrx4 were silenced simultaneously to investigate the synergistic effects of these genes on the physiological function of E. gracilis. The suppression of cytosolic EgGPXL genes was unable to induce any critical phenomena in Euglena under normal (100 μmol photons m-2 s-1) and high-light conditions (350 μmol photons m-2 s-1) at both autotrophic and heterotrophic states. Unexpectedly, the suppression of EgGPXL genes was able to rescue the EgPrx1/EgPrx4-silenced cell line from a critical situation. This study explored the potential resilience of Euglena to ROS, even with restriction of the cytosolic antioxidant system, indicating the involvement of some compensatory mechanisms.
Collapse
Affiliation(s)
- Md Topu Raihan
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8550, Japan;
| | - Takahiro Ishikawa
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8550, Japan;
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan
| |
Collapse
|
3
|
Ishida T, Tanaka Y, Maruta T, Ishikawa T. The D-mannose/L-galactose pathway plays a predominant role in ascorbate biosynthesis in the liverwort Marchantia polymorpha but is not regulated by light and oxidative stress. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:805-817. [PMID: 37983622 DOI: 10.1111/tpj.16530] [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: 07/11/2023] [Revised: 10/06/2023] [Accepted: 10/21/2023] [Indexed: 11/22/2023]
Abstract
Ascorbate plays an indispensable role in plants, functioning as both an antioxidant and a cellular redox buffer. It is widely acknowledged that the ascorbate biosynthesis in the photosynthetic tissues of land plants is governed by light-mediated regulation of the D-mannose/L-galactose (D-Man/L-Gal) pathway. At the core of this light-dependent regulation lies the VTC2 gene, encoding the rate-limiting enzyme GDP-L-Gal phosphorylase. The VTC2 expression is regulated by signals via the photosynthetic electron transport system. In this study, we directed our attention to the liverwort Marchantia polymorpha, representing one of the basal land plants, enabling us to conduct an in-depth analysis of its ascorbate biosynthesis. The M. polymorpha genome harbors a solitary gene for each enzyme involved in the D-Man/L-Gal pathway, including VTC2, along with three lactonase orthologs, which may be involved in the alternative ascorbate biosynthesis pathway. Through supplementation experiments with potential precursors, we observed that only L-Gal exhibited effectiveness in ascorbate biosynthesis. Furthermore, the generation of VTC2-deficient mutants through genome editing unveiled the inability of thallus regeneration in the absence of L-Gal supplementation, thereby revealing the importance of the D-Man/L-Gal pathway in ascorbate biosynthesis within M. polymorpha. Interestingly, gene expression analyses unveiled a distinct characteristic of M. polymorpha, where none of the genes associated with the D-Man/L-Gal pathway, including VTC2, showed upregulation in response to light, unlike other known land plants. This study sheds light on the exceptional nature of M. polymorpha as a land plant that has evolved distinctive mechanisms concerning ascorbate biosynthesis and its regulation.
Collapse
Affiliation(s)
- Tetsuya Ishida
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Yasuhiro Tanaka
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-minami, Tottori, 680-8550, Japan
| | - Takanori Maruta
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-minami, Tottori, 680-8550, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Takahiro Ishikawa
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-minami, Tottori, 680-8550, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| |
Collapse
|
4
|
Chen Z, Zhu J, Du M, Chen Z, Liu Q, Zhu H, Lei A, Wang J. A Synthetic Biology Perspective on the Bioengineering Tools for an Industrial Microalga: Euglena gracilis. Front Bioeng Biotechnol 2022; 10:882391. [PMID: 35464731 PMCID: PMC9020809 DOI: 10.3389/fbioe.2022.882391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 03/11/2022] [Indexed: 11/13/2022] Open
Abstract
Euglena is a genus of single-celled eukaryotes that show both plant- and animal-like characteristics. Euglena gracilis, a model species, is of great academic interest for studying endosymbiosis and chloroplast development. As an industrial species, E. gracilis is also of primary biotechnological and economic importance as high value-added food, medicine, and cosmetic and high-quality feedstock for jet-fuel production because of its cells containing many high-value products, such as vitamins, amino acids, pigments, unsaturated fatty acids, and carbohydrate paramylon, as metabolites. For more than half a century, E. gracilis has been used as an industrial biotechnology platform for fundamental biology research, mainly exploring relevant physiological and biochemical method studies. Although many researchers focused on genetic engineering tools for E. gracilis in recent years, little progress has been achieved because of the lack of high-quality genome information and efficient techniques for genetic operation. This article reviewed the progress of the genetic transformation of E. gracilis, including methods for the delivery of exogenous materials and other advanced biotechnological tools for E. gracilis, such as CRISPR and RNA interference. We hope to provide a reference to improve the research in functional genomics and synthetic biology of Euglena.
Collapse
Affiliation(s)
- Zhenfan Chen
- College of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, China
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Jiayi Zhu
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Ming Du
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Zixi Chen
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Qiong Liu
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
- Shenzhen-Hong Kong Institute of Brain Science, Shenzhen, China
| | - Hui Zhu
- College of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, China
| | - Anping Lei
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Jiangxin Wang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
- *Correspondence: Jiangxin Wang,
| |
Collapse
|
5
|
Identification of the Aldo-Keto Reductase Responsible for d-Galacturonic Acid Conversion to l-Galactonate in Saccharomyces cerevisiae. J Fungi (Basel) 2021; 7:jof7110914. [PMID: 34829203 PMCID: PMC8622349 DOI: 10.3390/jof7110914] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/22/2021] [Accepted: 10/25/2021] [Indexed: 12/03/2022] Open
Abstract
d-galacturonic acid (d-GalUA) is the main constituent of pectin, a complex polysaccharide abundant in several agro-industrial by-products such as sugar beet pulp or citrus peel. During several attempts to valorise d-GalUA by engineering the popular cell factory Saccharomyces cerevisiae, it became obvious that d-GalUA is, to a certain degree, converted to l-galactonate (l-GalA) by an endogenous enzymatic activity. The goal of the current work was to clarify the identity of the responsible enzyme(s). A protein homology search identified three NADPH-dependent unspecific aldo-keto reductases in baker’s yeast (encoded by GCY1, YPR1 and GRE3) that show sequence similarities to known d-GalUA reductases from filamentous fungi. Characterization of the respective deletion mutants and an in vitro enzyme assay with a Gcy1 overproducing strain verified that Gcy1 is mainly responsible for the detectable reduction of d-GalUA to l-GalA.
Collapse
|
6
|
Sodeyama T, Nishikawa H, Harai K, Takeshima D, Sawa Y, Maruta T, Ishikawa T. The d-mannose/l-galactose pathway is the dominant ascorbate biosynthetic route in the moss Physcomitrium patens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 107:1724-1738. [PMID: 34245628 DOI: 10.1111/tpj.15413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/16/2021] [Accepted: 07/06/2021] [Indexed: 05/14/2023]
Abstract
Ascorbate is an abundant and indispensable redox compound in plants. Genetic and biochemical studies have established the d-mannose/l-galactose (d-Man/l-Gal) pathway as the predominant ascorbate biosynthetic pathway in streptophytes, while the d-galacturonate (d-GalUA) pathway is found in prasinophytes and euglenoids. Based on the presence of the complete set of genes encoding enzymes involved in the d-Man/l-Gal pathway and an orthologous gene encoding aldonolactonase (ALase) - a key enzyme for the d-GalUA pathway - Physcomitrium patens may possess both pathways. Here, we have characterized the moss ALase as a functional lactonase and evaluated the ascorbate biosynthesis capability of the two pathways using knockout mutants. Physcomitrium patens expresses two ALase paralogs, namely PpALase1 and PpALase2. Kinetic analyses with recombinant enzymes indicated that PpALase1 is a functional enzyme catalyzing the conversion of l-galactonic acid to the final precursor l-galactono-1,4-lactone and that it also reacts with dehydroascorbate as a substrate. Interestingly, mutants lacking PpALase1 (Δal1) showed 1.2-fold higher total ascorbate content than the wild type, and their dehydroascorbate content was increased by 50% compared with that of the wild type. In contrast, the total ascorbate content of mutants lacking PpVTC2-1 (Δvtc2-1) or PpVTC2-2 (Δvtc2-2), which encode the rate-limiting enzyme GDP-l-Gal phosphorylase in the d-Man/l-Gal pathway, was markedly decreased to 46 and 17%, respectively, compared with that of the wild type. Taken together, the dominant ascorbate biosynthetic pathway in P. patens is the d-Man/l-Gal pathway, not the d-GalUA pathway, and PpALase1 may play a significant role in ascorbate metabolism by facilitating dehydroascorbate degradation rather than ascorbate biosynthesis.
Collapse
Affiliation(s)
- Tsubasa Sodeyama
- Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Hitoshi Nishikawa
- Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Kenji Harai
- Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Daiki Takeshima
- Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Yoshihiro Sawa
- Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Takanori Maruta
- Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Takahiro Ishikawa
- Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| |
Collapse
|
7
|
Tamaki S, Mochida K, Suzuki K. Diverse Biosynthetic Pathways and Protective Functions against Environmental Stress of Antioxidants in Microalgae. PLANTS (BASEL, SWITZERLAND) 2021; 10:1250. [PMID: 34205386 PMCID: PMC8234872 DOI: 10.3390/plants10061250] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 01/08/2023]
Abstract
Eukaryotic microalgae have been classified into several biological divisions and have evolutionarily acquired diverse morphologies, metabolisms, and life cycles. They are naturally exposed to environmental stresses that cause oxidative damage due to reactive oxygen species accumulation. To cope with environmental stresses, microalgae contain various antioxidants, including carotenoids, ascorbate (AsA), and glutathione (GSH). Carotenoids are hydrophobic pigments required for light harvesting, photoprotection, and phototaxis. AsA constitutes the AsA-GSH cycle together with GSH and is responsible for photooxidative stress defense. GSH contributes not only to ROS scavenging, but also to heavy metal detoxification and thiol-based redox regulation. The evolutionary diversity of microalgae influences the composition and biosynthetic pathways of these antioxidants. For example, α-carotene and its derivatives are specific to Chlorophyta, whereas diadinoxanthin and fucoxanthin are found in Heterokontophyta, Haptophyta, and Dinophyta. It has been suggested that AsA is biosynthesized via the plant pathway in Chlorophyta and Rhodophyta and via the Euglena pathway in Euglenophyta, Heterokontophyta, and Haptophyta. The GSH biosynthetic pathway is conserved in all biological kingdoms; however, Euglenophyta are able to synthesize an additional thiol antioxidant, trypanothione, using GSH as the substrate. In the present study, we reviewed and discussed the diversity of microalgal antioxidants, including recent findings.
Collapse
Affiliation(s)
- Shun Tamaki
- Microalgae Production Control Technology Laboratory, RIKEN Baton Zone Program, Yokohama 230-0045, Japan; (K.M.); (K.S.)
| | - Keiichi Mochida
- Microalgae Production Control Technology Laboratory, RIKEN Baton Zone Program, Yokohama 230-0045, Japan; (K.M.); (K.S.)
- RIKEN Center for Sustainable Resource Science, Yokohama 230-0045, Japan
- Kihara Institute for Biological Research, Yokohama City University, Yokohama 230-0045, Japan
- School of Information and Data Sciences, Nagasaki University, Nagasaki 852-8521, Japan
| | - Kengo Suzuki
- Microalgae Production Control Technology Laboratory, RIKEN Baton Zone Program, Yokohama 230-0045, Japan; (K.M.); (K.S.)
- euglena Co., Ltd., Tokyo 108-0014, Japan
| |
Collapse
|
8
|
Kim M, Cha IT, Lee KE, Lee EY, Park SJ. Genomics Reveals the Metabolic Potential and Functions in the Redistribution of Dissolved Organic Matter in Marine Environments of the Genus Thalassotalea. Microorganisms 2020; 8:microorganisms8091412. [PMID: 32937826 PMCID: PMC7564069 DOI: 10.3390/microorganisms8091412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 09/11/2020] [Indexed: 11/16/2022] Open
Abstract
Members of the bacterial genus Thalassotalea have been isolated recently from various marine environments, including marine invertebrates. A metagenomic study of the Deepwater Horizon oil plume has identified genes involved in aromatic hydrocarbon degradation in the Thalassotalea genome, shedding light on its potential role in the degradation of crude oils. However, the genomic traits of the genus are not well-characterized, despite the ability of the species to degrade complex natural compounds, such as agar, gelatin, chitin, or starch. Here, we obtained a complete genome of a new member of the genus, designated PS06, isolated from marine sediments containing dead marine benthic macroalgae. Unexpectedly, strain PS06 was unable to grow using most carbohydrates as sole carbon sources, which is consistent with the finding of few ABC transporters in the PS06 genome. A comparative analysis of 12 Thalassotalea genomes provided insights into their metabolic potential (e.g., microaerobic respiration and carbohydrate utilization) and evolutionary stability [including a low abundance of clustered regularly interspaced short palindromic repeats (CRISPR) loci and prophages]. The diversity and frequency of genes encoding extracellular enzymes for carbohydrate metabolism in the 12 genomes suggest that members of Thalassotalea contribute to nutrient cycling by the redistribution of dissolved organic matter in marine environments. Our study improves our understanding of the ecological and genomic properties of the genus Thalassotalea.
Collapse
Affiliation(s)
- Minji Kim
- Department of Biology, Jeju National University, 102 Jejudaehak-ro, Jeju 63243, Korea;
| | - In-Tae Cha
- Microorganism Resources Division, National Institute of Biological Resources, Incheon 22689, Korea; (I.-T.C.); (K.-E.L.)
| | - Ki-Eun Lee
- Microorganism Resources Division, National Institute of Biological Resources, Incheon 22689, Korea; (I.-T.C.); (K.-E.L.)
| | - Eun-Young Lee
- Exhibition & Education Division, National Institute of Biological Resources, Incheon 22689, Korea;
| | - Soo-Je Park
- Department of Biology, Jeju National University, 102 Jejudaehak-ro, Jeju 63243, Korea;
- Correspondence: ; Tel.: +82-64-753-3524; Fax: +82-64-756-3541
| |
Collapse
|
9
|
Yabuta Y, Nagata R, Aoki Y, Kariya A, Wada K, Yanagimoto A, Hara H, Bito T, Okamoto N, Yoshida S, Ishihara A, Watanabe F. L-Ascorbate Biosynthesis Involves Carbon Skeleton Rearrangement in the Nematode Caenorhabditis elegans. Metabolites 2020; 10:metabo10080334. [PMID: 32824560 PMCID: PMC7463950 DOI: 10.3390/metabo10080334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/11/2020] [Accepted: 08/15/2020] [Indexed: 11/16/2022] Open
Abstract
Ascorbate (AsA) is required as a cofactor and is widely distributed in plants and animals. Recently, it has been suggested that the nematode Caenorhabditis elegans also synthesizes AsA. However, its biosynthetic pathway is still unknown. To further understand AsA biosynthesis in C. elegans, we analyzed the incorporation of the 13C atom into AsA using gas chromatography-mass spectrometry (GC-MS) in worms fed with D-Glc (1-13C)-labeled Escherichia coli. GC-MS analysis revealed that AsA biosynthesis in C. elegans, similarly to that in mammalian systems, involves carbon skeleton rearrangement. The addition of L-gulono-1,4-lactone, an AsA precursor in the mammalian pathway, significantly increased AsA level in C. elegans, whereas the addition of L-galactono-1,4-lactone, an AsA precursor in the plant and Euglena pathway, did not affect AsA level. The suppression of E03H4.3 (an ortholog of gluconolactonase) or the deficiency of F54D5.12 (an ortholog of L-gulono-1,4-lactone oxidase) significantly decreased AsA level in C. elegans. Although N2- and AsA-deficient F54D5.12 knockout mutant worm (tm6671) morphologies and the ratio of collagen to non-collagen protein did not show any significant differences, the mutant worms exhibited increased malondialdehyde levels and reduced lifespan compared with the N2 worms. In conclusion, our findings indicate that the AsA biosynthetic pathway is similar in C. elegans and mammals.
Collapse
Affiliation(s)
- Yukinori Yabuta
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
- Correspondence: ; Tel.: +81-857-31-5382
| | - Ryuta Nagata
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| | - Yuka Aoki
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| | - Ayumi Kariya
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| | - Kousuke Wada
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| | - Ayako Yanagimoto
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| | - Hiroka Hara
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| | - Tomohiro Bito
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| | - Naho Okamoto
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan;
| | - Shinichi Yoshida
- Electronic and Organic Material Laboratory, Tottori Institute of Industrial Technology, 7-1-1 Wakabadai-minami, Tottori 689-1112, Japan;
| | - Atsushi Ishihara
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| | - Fumio Watanabe
- Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan; (R.N.); (Y.A.); (A.K.); (K.W.); (A.Y.); (H.H.); (T.B.); (A.I.); (F.W.)
| |
Collapse
|
10
|
Khatiwada B, Sunna A, Nevalainen H. Molecular tools and applications of Euglena gracilis: From biorefineries to bioremediation. Biotechnol Bioeng 2020; 117:3952-3967. [PMID: 32710635 DOI: 10.1002/bit.27516] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 06/17/2020] [Accepted: 07/23/2020] [Indexed: 12/19/2022]
Abstract
Euglena gracilis is a promising source of commercially important metabolites such as vitamins, wax esters, paramylon, and amino acids. However, the molecular tools available to create improved Euglena strains are limited compared to other microorganisms that are currently exploited in the biotechnology industry. The complex poly-endosymbiotic nature of the Euglena genome is a major bottleneck for obtaining a complete genome sequence and thus represents a notable shortcoming in gaining molecular information of this organism. Therefore, the studies and applications have been more focused on using the wild-type strain or its variants and optimizing the nutrient composition and cultivation conditions to enhance the production of biomass and valuable metabolites. In addition to producing metabolites, the E. gracilis biorefinery concept also provides means for the production of biofuels and biogas as well as residual biomass for the remediation of industrial and municipal wastewater. Using Euglena for bioremediation of environments contaminated with heavy metals is of special interest due to the strong ability of the organism to accumulate and sequester these compounds. The published draft genome and transcriptome will serve as a basis for further molecular studies of Euglena and provide a guide for the engineering of metabolic pathways of relevance for the already established as well as novel applications.
Collapse
Affiliation(s)
- Bishal Khatiwada
- Department Molecular Sciences, Macquarie University, Sydney, Australia.,Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, Australia
| | - Anwar Sunna
- Department Molecular Sciences, Macquarie University, Sydney, Australia.,Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, Australia
| | - Helena Nevalainen
- Department Molecular Sciences, Macquarie University, Sydney, Australia.,Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, Australia
| |
Collapse
|
11
|
Fayyaz M, Chew KW, Show PL, Ling TC, Ng IS, Chang JS. Genetic engineering of microalgae for enhanced biorefinery capabilities. Biotechnol Adv 2020; 43:107554. [PMID: 32437732 DOI: 10.1016/j.biotechadv.2020.107554] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 05/06/2020] [Accepted: 05/06/2020] [Indexed: 02/06/2023]
Abstract
Microalgae-based bioproducts are in limelight because of their promising future, novel characteristics, the current situation of population needs, and rising prices of rapidly depleting energy resources. Algae-based products are considered as clean sustainable energy and food resources. At present, they are not commercialized due to their high production cost and low yield. In recent years, novel genome editing tools like RNAi, ZNFs, TALENs, and CRISPR/Cas9 are used to enhance the quality and quantity of the desired products. Genetic and metabolic engineering are frequently applied because of their rapid and precise results than random mutagenesis. Omic approaches help enhance biorefinery capabilities and are now in the developing stage for algae. The future is very bright for transgenic algae with increased biomass yield, carbon dioxide uptake rate, accumulating high-value compounds, reduction in cultivation, and production costs, thus reaching the goal in the global algal market and capital flow. However, microalgae are primary producers and any harmful exposure to the wild strains can affect the entire ecosystem. Therefore, strict regulation and monitoring are required to assess the potential risks before introducing genetically modified microalgae into the natural ecosystem.
Collapse
Affiliation(s)
- Mehmooda Fayyaz
- Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor, Malaysia
| | - Kit Wayne Chew
- School of Energy and Chemical Engineering, Xiamen University Malaysia, Jalan Sunsuria, Bandar Sunsuria, 43900 Sepang, Selangor, Malaysia
| | - Pau Loke Show
- Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor, Malaysia.
| | - Tau Chuan Ling
- Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - I-Son Ng
- Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan
| | - Jo-Shu Chang
- Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan; Department of Chemical and Materials Engineering, College of Engineering, Tunghai University, Taichung 407, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan.
| |
Collapse
|
12
|
Canton M, Drincovich MF, Lara MV, Vizzotto G, Walker RP, Famiani F, Bonghi C. Metabolism of Stone Fruits: Reciprocal Contribution Between Primary Metabolism and Cell Wall. FRONTIERS IN PLANT SCIENCE 2020; 11:1054. [PMID: 32733527 PMCID: PMC7363977 DOI: 10.3389/fpls.2020.01054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/26/2020] [Indexed: 05/08/2023]
Abstract
Cell wall turnover and modification in its composition are key factors during stone fruit development and patterning. Changes in cell wall disassembly and reassembly are essential for fruit growth and ripening. Modifications in cell wall composition, resulting in the formation of secondary cell walls, are necessary for producing the most distinctive trait of drupes: the lignified endocarp. The contribution of primary metabolism to cell wall synthesis has been investigated in detail, while the knowledge on the contribution of the cell wall to primary metabolites and related processes is still fragmented. In this review, starting from peculiarities of cell wall of drupes cells (in mesocarp and endocarp layers), we discuss the structure and composition of cell wall, processes related to its modification and contribution to the synthesis of primary metabolites. In particular, our attention has been focused on the ascorbate synthesis cell wall-related and on the potential role of cyanogenic compounds in the deposition of the secondary cell wall.
Collapse
Affiliation(s)
- Monica Canton
- Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova Agripolis, Legnaro, Italy
| | - María F. Drincovich
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Centro de Estudios Fotosintéticos y Bioquímicos, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - María V. Lara
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Centro de Estudios Fotosintéticos y Bioquímicos, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Giannina Vizzotto
- Department of Agricultural, Food, Environmental, and Animal Sciences, University of Udine, Udine, Italy
| | - Robert P. Walker
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Italy
| | - Franco Famiani
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Italy
| | - Claudio Bonghi
- Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova Agripolis, Legnaro, Italy
- *Correspondence: Claudio Bonghi,
| |
Collapse
|
13
|
Wagschal K, Jordan DB, Hart-Cooper WM, Chan VJ. Penicillium camemberti galacturonate reductase: C-1 oxidation/reduction of uronic acids and substrate inhibition mitigation by aldonic acids. Int J Biol Macromol 2019; 153:1090-1098. [PMID: 31756465 DOI: 10.1016/j.ijbiomac.2019.10.239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 10/17/2019] [Accepted: 10/25/2019] [Indexed: 11/24/2022]
Abstract
The enzyme galacturonate oxidoreductase PcGOR from Penicillium camemberti reduces the C-1 carbon of D-glucuronate and C-4 epimer D-galacturonate to their corresponding aldonic acids, important reactions in both pectin catabolism and ascorbate biosynthesis. PcGOR was active on both glucuronic acid and galacturonic acid, with similar substrate specificities (kcat/Km) using the preferred co-substrate NADPH. Substrate acceptance extended to lactone congeners, and D-glucurono-3,6-lactone was converted to L-gulono-1,4-lactone, an immediate precursor of ascorbate. Reaction with glucuronate showed only minor substrate inhibition, and the product L-gulonate and L-gulono-1,4-lactone were both found to be competitive inhibitors with Ki in the low mM range. In contrast, reaction with C-4 epimer galacturonate displayed marked substrate inhibition. Moreover, the product L-galactonate and L-galactono-1,4-lactone were observed to mitigate substrate inhibition by galacturonate, with the lactone having a greater effect than the acid.
Collapse
Affiliation(s)
- Kurt Wagschal
- USDA Agricultural Research Service, Western Regional Research Center, Albany, CA 94710, USA.
| | - Douglas B Jordan
- USDA Agricultural Research Service, National Center for Agricultural Utilization Research, Peoria, IL 61604, USA
| | - William M Hart-Cooper
- USDA Agricultural Research Service, Western Regional Research Center, Albany, CA 94710, USA
| | - Victor J Chan
- USDA Agricultural Research Service, Western Regional Research Center, Albany, CA 94710, USA
| |
Collapse
|
14
|
Schittenhelm D, Neuss-Radu M, Verma N, Pink M, Schmitz-Spanke S. ROS and pentose phosphate pathway: mathematical modelling of the metabolic regulation in response to xenobiotic-induced oxidative stress and the proposed Impact of the gluconate shunt. Free Radic Res 2019; 53:979-992. [PMID: 31476923 DOI: 10.1080/10715762.2019.1660777] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Elevated intracellular levels of reactive oxygen species (ROS), e.g. resulting from exposure to xenobiotics, can cause severe damages. Antioxidant defence mechanisms, which involve regulation of enzyme activities, protect cells to a certain extent. Nevertheless, continuous or increased exposure can overwhelm this system resulting in an adverse cellular state. To simulate exposure scenarios and to investigate the transition to an adverse cellular state, a mathematical model for the dynamics of ROS in response to xenobiotic-induced oxidative stress has been developed. It is based on exposure experiments of human urothelial cells (RT4) to the nitrated polycyclic aromatic hydrocarbon 3-nitrobenzanthrone (3-NBA), a component of diesel engine exhaust, and takes into account the following metabolic pathways of the antioxidant defence system: glutathione redox cycle scavenging directly ROS, the pentose phosphate pathway and the gluconate shunt as NADPH supplier and the beginning of glycolysis. In addition, ROS generation due to the bioactivation of 3-NBA has been implemented. The regulation of enzyme activities plays an important role in the presented mathematical model. The in silico model consists of ordinary differential equations on the basis of enzyme kinetics and mass action for the metabolism of 3-NBA. Parameters are either estimated from performed in vitro experiments via least-squares fitting or obtained from the literature. The results underline the importance of the pentose phosphate pathway to cope with oxidative stress and suggest an important role of the gluconate shunt during low-dose exposure.
Collapse
Affiliation(s)
- Doris Schittenhelm
- Department of Mathematics, Friedrich-Alexander-Universität Erlangen-Nürnberg , Erlangen , Germany
| | - Maria Neuss-Radu
- Department of Mathematics, Friedrich-Alexander-Universität Erlangen-Nürnberg , Erlangen , Germany
| | - Nisha Verma
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, Friedrich-Alexander-Universität Erlangen-Nürnberg , Erlangen , Germany
| | - Mario Pink
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, Friedrich-Alexander-Universität Erlangen-Nürnberg , Erlangen , Germany
| | - Simone Schmitz-Spanke
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, Friedrich-Alexander-Universität Erlangen-Nürnberg , Erlangen , Germany
| |
Collapse
|
15
|
Ali B, Pantha S, Acharya R, Ueda Y, Wu LB, Ashrafuzzaman M, Ishizaki T, Wissuwa M, Bulley S, Frei M. Enhanced ascorbate level improves multi-stress tolerance in a widely grown indica rice variety without compromising its agronomic characteristics. JOURNAL OF PLANT PHYSIOLOGY 2019; 240:152998. [PMID: 31226542 DOI: 10.1016/j.jplph.2019.152998] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 05/26/2023]
Abstract
A biotechnological approach was adopted for increasing foliar ascorbate levels as a strategy to adapt a widely grown high yielding rice variety to multiple abiotic stresses. The variety IR64 (Oryza sativa L. ssp. indica) was engineered to express the ascorbate biosynthesis gene GDP-L-galactose phosphorylase (AcGGP) from kiwifruit (Actinidia chinensis Planch.) under the control of a leaf-specific promoter of the Leaf Panicle 2 (LP2) gene. Transgene expression increased foliar ascorbate levels up to >2.5 fold but did not lead to any changes in morphological traits (seed yield, sterility rate, grain weight, and biomass) in non-stress conditions. We then hypothesized that enhanced foliar ascorbate would confer multi-stress tolerance. Indeed transgenic lines were more tolerant to salinity in terms of lipid peroxidation and foliar symptoms, and to drought in terms of lipid peroxidation and post-drought recovery (number of dead leaves). A significantly better performance in ozone stress was seen only when ozone coincided with salinity. However, no differences between transgenic lines and wild types occurred when plants were subjected to toxicities in redox-active transition metals, i.e. iron and manganese, although plants showed clear symptoms of oxidative stress. Moreover, no differential response to zinc deficiency was observed, because the background genotype IR64 was not sensitive to this stress. Taken together, our study helps to identify stress conditions that can be mitigated by enhancing foliar ascorbate levels, and therefore facilitates an adaptive breeding approach for multiple stresses that would not imply any yield penalty.
Collapse
Affiliation(s)
- Basharat Ali
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Germany; Department of Agronomy, University of Agriculture Faisalabad 38040, Pakistan
| | - Sumitra Pantha
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Germany; Nepal Agricultural Research Council, Nepal
| | - Roshan Acharya
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Germany
| | - Yoshiaki Ueda
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Germany
| | - Lin-Bo Wu
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Germany
| | - Md Ashrafuzzaman
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Germany
| | - Takuma Ishizaki
- Japan International Research Center for Agricultural Sciences (JIRCAS), Ishigaki, Japan
| | - Matthias Wissuwa
- Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Japan
| | - Sean Bulley
- Plant and Food Research Ltd., Te Puke, New Zealand
| | - Michael Frei
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Germany.
| |
Collapse
|
16
|
Vesteg M, Hadariová L, Horváth A, Estraño CE, Schwartzbach SD, Krajčovič J. Comparative molecular cell biology of phototrophic euglenids and parasitic trypanosomatids sheds light on the ancestor of Euglenozoa. Biol Rev Camb Philos Soc 2019; 94:1701-1721. [PMID: 31095885 DOI: 10.1111/brv.12523] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 04/30/2019] [Accepted: 05/02/2019] [Indexed: 01/23/2023]
Abstract
Parasitic trypanosomatids and phototrophic euglenids are among the most extensively studied euglenozoans. The phototrophic euglenid lineage arose relatively recently through secondary endosymbiosis between a phagotrophic euglenid and a prasinophyte green alga that evolved into the euglenid secondary chloroplast. The parasitic trypanosomatids (i.e. Trypanosoma spp. and Leishmania spp.) and the freshwater phototrophic euglenids (i.e. Euglena gracilis) are the most evolutionary distant lineages in the Euglenozoa phylogenetic tree. The molecular and cell biological traits they share can thus be considered as ancestral traits originating in the common euglenozoan ancestor. These euglenozoan ancestral traits include common mitochondrial presequence motifs, respiratory chain complexes containing various unique subunits, a unique ATP synthase structure, the absence of mitochondria-encoded transfer RNAs (tRNAs), a nucleus with a centrally positioned nucleolus, closed mitosis without dissolution of the nuclear membrane and nucleoli, a nuclear genome containing the unusual 'J' base (β-D-glucosyl-hydroxymethyluracil), processing of nucleus-encoded precursor messenger RNAs (pre-mRNAs) via spliced-leader RNA (SL-RNA) trans-splicing, post-transcriptional gene silencing by the RNA interference (RNAi) pathway and the absence of transcriptional regulation of nuclear gene expression. Mitochondrial uridine insertion/deletion RNA editing directed by guide RNAs (gRNAs) evolved in the ancestor of the kinetoplastid lineage. The evolutionary origin of other molecular features known to be present only in either kinetoplastids (i.e. polycistronic transcripts, compaction of nuclear genomes) or euglenids (i.e. monocistronic transcripts, huge genomes, many nuclear cis-spliced introns, polyproteins) is unclear.
Collapse
Affiliation(s)
- Matej Vesteg
- Department of Biology and Ecology, Faculty of Natural Sciences, Matej Bel University, 974 01, Banská Bystrica, Slovakia
| | - Lucia Hadariová
- Biotechnology and Biomedicine Center of the Academy of Sciences and Charles University in Vestec (BIOCEV), 252 50, Vestec, Czech Republic.,Department of Parasitology, Faculty of Science, Charles University in Prague, 128 44, Prague, Czech Republic
| | - Anton Horváth
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, 842 15, Bratislava, Slovakia
| | - Carlos E Estraño
- Department of Biological Sciences, University of Memphis, Memphis, TN, 38152-3560, USA
| | - Steven D Schwartzbach
- Department of Biological Sciences, University of Memphis, Memphis, TN, 38152-3560, USA
| | - Juraj Krajčovič
- Department of Biology, Faculty of Natural Sciences, University of ss. Cyril and Methodius, 917 01, Trnava, Slovakia
| |
Collapse
|
17
|
Strobbe S, De Lepeleire J, Van Der Straeten D. From in planta Function to Vitamin-Rich Food Crops: The ACE of Biofortification. FRONTIERS IN PLANT SCIENCE 2018; 9:1862. [PMID: 30619424 PMCID: PMC6305313 DOI: 10.3389/fpls.2018.01862] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/03/2018] [Indexed: 05/11/2023]
Abstract
Humans are highly dependent on plants to reach their dietary requirements, as plant products contribute both to energy and essential nutrients. For many decades, plant breeders have been able to gradually increase yields of several staple crops, thereby alleviating nutritional needs with varying degrees of success. However, many staple crops such as rice, wheat and corn, although delivering sufficient calories, fail to satisfy micronutrient demands, causing the so called 'hidden hunger.' Biofortification, the process of augmenting nutritional quality of food through the use of agricultural methodologies, is a pivotal asset in the fight against micronutrient malnutrition, mainly due to vitamin and mineral deficiencies. Several technical advances have led to recent breakthroughs. Nutritional genomics has come to fruition based on marker-assisted breeding enabling rapid identification of micronutrient related quantitative trait loci (QTL) in the germplasm of interest. As a complement to these breeding techniques, metabolic engineering approaches, relying on a continuously growing fundamental knowledge of plant metabolism, are able to overcome some of the inevitable pitfalls of breeding. Alteration of micronutrient levels does also require fundamental knowledge about their role and influence on plant growth and development. This review focuses on our knowledge about provitamin A (beta-carotene), vitamin C (ascorbate) and the vitamin E group (tocochromanols). We begin by providing an overview of the functions of these vitamins in planta, followed by highlighting some of the achievements in the nutritional enhancement of food crops via conventional breeding and genetic modification, concluding with an evaluation of the need for such biofortification interventions. The review further elaborates on the vast potential of creating nutritionally enhanced crops through multi-pathway engineering and the synergistic potential of conventional breeding in combination with genetic engineering, including the impact of novel genome editing technologies.
Collapse
|
18
|
Koç I, Yuksel I, Caetano-Anollés G. Metabolite-Centric Reporter Pathway and Tripartite Network Analysis of Arabidopsis Under Cold Stress. Front Bioeng Biotechnol 2018; 6:121. [PMID: 30258841 PMCID: PMC6143811 DOI: 10.3389/fbioe.2018.00121] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/13/2018] [Indexed: 12/22/2022] Open
Abstract
The study of plant resistance to cold stress and the metabolic processes underlying its molecular mechanisms benefit crop improvement programs. Here we investigate the effects of cold stress on the metabolic pathways of Arabidopsis when directly inferred at system level from transcriptome data. A metabolite-centric reporter pathway analysis approach enabled the computation of metabolites associated with transcripts at four time points of cold treatment. Tripartite networks of gene-metabolite-pathway connectivity outlined the response of metabolites and pathways to cold stress. Our metabolome-independent analysis revealed stress-associated metabolites in pathway routes of the cold stress response, including amino acid, carbohydrate, lipid, hormone, energy, photosynthesis, and signaling pathways. Cold stress first triggered the mobilization of energy from glycolysis and ethanol degradation to enhance TCA cycle activity via acetyl-CoA. Interestingly, tripartite networks lacked power law behavior and scale free connectivity, favoring modularity. Network rewiring explicitly involved energetics, signal, carbon and redox metabolisms and membrane remodeling.
Collapse
Affiliation(s)
- Ibrahim Koç
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze, Turkey
| | - Isa Yuksel
- Department of Bioengineering, Gebze Technical University, Gebze, Turkey
| | | |
Collapse
|
19
|
Waldron FM, Stone GN, Obbard DJ. Metagenomic sequencing suggests a diversity of RNA interference-like responses to viruses across multicellular eukaryotes. PLoS Genet 2018; 14:e1007533. [PMID: 30059538 PMCID: PMC6085071 DOI: 10.1371/journal.pgen.1007533] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 08/09/2018] [Accepted: 07/04/2018] [Indexed: 11/24/2022] Open
Abstract
RNA interference (RNAi)-related pathways target viruses and transposable element (TE) transcripts in plants, fungi, and ecdysozoans (nematodes and arthropods), giving protection against infection and transmission. In each case, this produces abundant TE and virus-derived 20-30nt small RNAs, which provide a characteristic signature of RNAi-mediated defence. The broad phylogenetic distribution of the Argonaute and Dicer-family genes that mediate these pathways suggests that defensive RNAi is ancient, and probably shared by most animal (metazoan) phyla. Indeed, while vertebrates had been thought an exception, it has recently been argued that mammals also possess an antiviral RNAi pathway, although its immunological relevance is currently uncertain and the viral small RNAs (viRNAs) are not easily detectable. Here we use a metagenomic approach to test for the presence of viRNAs in five species from divergent animal phyla (Porifera, Cnidaria, Echinodermata, Mollusca, and Annelida), and in a brown alga-which represents an independent origin of multicellularity from plants, fungi, and animals. We use metagenomic RNA sequencing to identify around 80 virus-like contigs in these lineages, and small RNA sequencing to identify viRNAs derived from those viruses. We identified 21U small RNAs derived from an RNA virus in the brown alga, reminiscent of plant and fungal viRNAs, despite the deep divergence between these lineages. However, contrary to our expectations, we were unable to identify canonical (i.e. Drosophila- or nematode-like) viRNAs in any of the animals, despite the widespread presence of abundant micro-RNAs, and somatic transposon-derived piwi-interacting RNAs. We did identify a distinctive group of small RNAs derived from RNA viruses in the mollusc. However, unlike ecdysozoan viRNAs, these had a piRNA-like length distribution but lacked key signatures of piRNA biogenesis. We also identified primary piRNAs derived from putatively endogenous copies of DNA viruses in the cnidarian and the echinoderm, and an endogenous RNA virus in the mollusc. The absence of canonical virus-derived small RNAs from our samples may suggest that the majority of animal phyla lack an antiviral RNAi response. Alternatively, these phyla could possess an antiviral RNAi response resembling that reported for vertebrates, with cryptic viRNAs not detectable through simple metagenomic sequencing of wild-type individuals. In either case, our findings show that the antiviral RNAi responses of arthropods and nematodes, which are highly divergent from each other and from that of plants and fungi, are also highly diverged from the most likely ancestral metazoan state.
Collapse
Affiliation(s)
- Fergal M. Waldron
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
| | - Graham N. Stone
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
| | - Darren J. Obbard
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
- Centre for Immunity Infection and Evolution, University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom
| |
Collapse
|
20
|
Smirnoff N. Ascorbic acid metabolism and functions: A comparison of plants and mammals. Free Radic Biol Med 2018; 122:116-129. [PMID: 29567393 PMCID: PMC6191929 DOI: 10.1016/j.freeradbiomed.2018.03.033] [Citation(s) in RCA: 312] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 03/15/2018] [Accepted: 03/17/2018] [Indexed: 02/07/2023]
Abstract
Ascorbic acid is synthesised by eukaryotes, the known exceptions being primates and some other animal groups which have lost functional gulonolactone oxidase. Prokaryotes do not synthesise ascorbate and do not need an ascorbate supply, so the functions that are essential for mammals and plants are not required or are substituted by other compounds. The ability of ascorbate to donate electrons enables it to act as a free radical scavenger and to reduce higher oxidation states of iron to Fe2+. These reactions are the basis of its biological activity along with the relative stability of the resulting resonance stabilised monodehydroascorbate radical. The importance of these properties is emphasised by the evolution of at least three biosynthetic pathways and production of an ascorbate analogue, erythroascorbate, by fungi. The iron reducing activity of ascorbate maintains the reactive centre Fe2+ of 2-oxoglutarate-dependent dioxygenases (2-ODDs) thus preventing inactivation. These enzymes have diverse functions and, recently, the possibility that ascorbate status in mammals could influence 2-ODDs involved in histone and DNA demethylation thereby influencing stem cell differentiation and cancer has been uncovered. Ascorbate is involved in iron uptake and transport in plants and animals. While the above biochemical functions are shared between mammals and plants, ascorbate peroxidase (APX) is an enzyme family limited to plants and photosynthetic protists. It provides these organisms with increased capacity to remove H2O2 produced by photosynthetic electron transport and photorespiration. The Fe reducing activity of ascorbate enables hydroxyl radical production (pro-oxidant effect) and the reactivity of dehydroascorbate (DHA) and reaction of its degradation products with proteins (dehydroascorbylation and glycation) is potentially damaging. Ascorbate status influences gene expression in plants and mammals but at present there is little evidence that it acts as a specific signalling molecule. It most likely acts indirectly by influencing the redox state of thiols and 2-ODD activity. However, the possibility that dehydroascorbylation is a regulatory post-translational protein modification could be explored.
Collapse
Affiliation(s)
- Nicholas Smirnoff
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
| |
Collapse
|
21
|
Peng D, Zhou B, Jiang Y, Tan X, Yuan D, Zhang L. Enhancing freezing tolerance of Brassica napus L. by overexpression of a stearoyl-acyl carrier protein desaturase gene (SAD) from Sapium sebiferum (L.) Roxb. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 272:32-41. [PMID: 29807604 DOI: 10.1016/j.plantsci.2018.03.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 03/25/2018] [Accepted: 03/28/2018] [Indexed: 05/06/2023]
Abstract
Sapium sebiferum (L.) Roxb. is an important woody oil tree and traditional herbal medicine in China. Stearoyl-acyl carrier protein desaturase (SAD) is a dehydrogenase enzyme that plays a key role in the transformation of saturated fatty acids into unsaturated fatty acids in oil; these fatty acids greatly influence the freezing tolerance of plants. However, it remains unclear whether freezing tolerance can be regulated by the expression level of SsSAD in S. sebiferum L. Our research indicated that SsSAD expression in S. sebiferum L. increased under freezing stress. To further confirm this result, we constructed a pEGAD-SsSAD vector and transformed it into B. napus L. W10 by Agrobacterium tumefaciens-mediated transformation. Transgenic plants that overexpressed the SsSAD gene exhibited significantly higher linoleic (18:2) and linolenic acid (18:3) content and advanced freezing tolerance. These results suggest that SsSAD overexpression in B. napus L. can increase the content of polyunsaturated fatty acids (PUFAs) such as linoleic (18:2) and linolenic acid (18:3), which are likely pivotal in improving freezing tolerance in B. napus L. plants. Thus, SsSAD overexpression could be useful in the production of freeze-tolerant varieties of B. napus L.
Collapse
Affiliation(s)
- Dan Peng
- College of Bioscience and Biotechnology of Central South University of Forestry and Technology, 410018, Changsha, China; Forestry Biotechnology Hunan Key Laboratories, Hunan Changsha, 410018, China
| | - Bo Zhou
- College of Bioscience and Biotechnology of Central South University of Forestry and Technology, 410018, Changsha, China; Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, 410018, Changsha, China; Collaborative Innovation Central of Cultivation and Utilization for Non-Wood Forest Tree Central South University of Forestry and Technology, 410018, Changsha, China; Forestry Biotechnology Hunan Key Laboratories, Hunan Changsha, 410018, China.
| | - Yueqiao Jiang
- College of Bioscience and Biotechnology of Central South University of Forestry and Technology, 410018, Changsha, China
| | - XiaoFeng Tan
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, 410018, Changsha, China; Collaborative Innovation Central of Cultivation and Utilization for Non-Wood Forest Tree Central South University of Forestry and Technology, 410018, Changsha, China
| | - DeYi Yuan
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, 410018, Changsha, China; Collaborative Innovation Central of Cultivation and Utilization for Non-Wood Forest Tree Central South University of Forestry and Technology, 410018, Changsha, China
| | - Lin Zhang
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, 410018, Changsha, China; Collaborative Innovation Central of Cultivation and Utilization for Non-Wood Forest Tree Central South University of Forestry and Technology, 410018, Changsha, China
| |
Collapse
|
22
|
Hasan MT, Sun A, Mirzaei M, Te'o J, Hobba G, Sunna A, Nevalainen H. A comprehensive assessment of the biosynthetic pathways of ascorbate, α-tocopherol and free amino acids in Euglena gracilis var. saccharophila. ALGAL RES 2017. [DOI: 10.1016/j.algal.2017.08.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
23
|
Biochemistry and Physiology of Reactive Oxygen Species in Euglena. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 979:47-64. [PMID: 28429317 DOI: 10.1007/978-3-319-54910-1_4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Reactive oxygen species (ROS) such as superoxide and hydrogen peroxide are by-products of various metabolic processes in aerobic organisms including Euglena. Chloroplasts and mitochondria are the main sites of ROS generation by photosynthesis and respiration, respectively, through the active electron transport chain. An efficient antioxidant network is required to maintain intracellular ROS pools at optimal conditions for redox homeostasis. A comparison with the networks of plants and animals revealed that Euglena has acquired some aspects of ROS metabolic process. Euglena lacks catalase and a typical selenocysteine containing animal-type glutathione peroxidase for hydrogen peroxide scavenging, but contains enzymes involved in ascorbate-glutathione cycle solely in the cytosol. Ascorbate peroxidase in Euglena, which plays a central role in the ascorbate-glutathione cycle, forms a unique intra-molecular dimer structure that is related to the recognition of peroxides. We recently identified peroxiredoxin and NADPH-dependent thioredoxin reductase isoforms in cellular compartments including chloroplasts and mitochondria, indicating the physiological significance of the thioredoxin system in metabolism of ROS. Besides glutathione, Euglena contains the unusual thiol compound trypanothione, an unusual form of glutathione involving two molecules of glutathione joined by a spermidine linker, which has been identified in pathogenic protists such as Trypanosomatida and Schizopyrenida. Furthermore, in contrast to plants, photosynthesis by Euglena is not susceptible to hydrogen peroxide because of resistance of the Calvin cycle enzymes fructose-1,6-bisphosphatse, NADP+-glyceraldehyde-3-phosphatase, sedoheptulose-1,7-bisphosphatase, and phosphoribulokinase to hydrogen peroxide. Consequently, these characteristics of Euglena appear to exemplify a strategy for survival and adaptation to various environmental conditions during the evolutionary process of euglenoids.
Collapse
|
24
|
Biochemistry and Physiology of Vitamins in Euglena. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 979:65-90. [DOI: 10.1007/978-3-319-54910-1_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
|
25
|
Ruggieri V, Bostan H, Barone A, Frusciante L, Chiusano ML. Integrated bioinformatics to decipher the ascorbic acid metabolic network in tomato. PLANT MOLECULAR BIOLOGY 2016; 91:397-412. [PMID: 27007138 DOI: 10.1007/s11103-016-0469-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 03/07/2016] [Indexed: 06/05/2023]
Abstract
Ascorbic acid is involved in a plethora of reactions in both plant and animal metabolism. It plays an essential role neutralizing free radicals and acting as enzyme co-factor in several reaction. Since humans are ascorbate auxotrophs, enhancing the nutritional quality of a widely consumed vegetable like tomato is a desirable goal. Although the main reactions of the ascorbate biosynthesis, recycling and translocation pathways have been characterized, the assignment of tomato genes to each enzymatic step of the entire network has never been reported to date. By integrating bioinformatics approaches, omics resources and transcriptome collections today available for tomato, this study provides an overview on the architecture of the ascorbate pathway. In particular, 237 tomato loci were associated with the different enzymatic steps of the network, establishing the first comprehensive reference collection of candidate genes based on the recently released tomato gene annotation. The co-expression analyses performed by using RNA-Seq data supported the functional investigation of main expression patterns for the candidate genes and highlighted a coordinated spatial-temporal regulation of genes of the different pathways across tissues and developmental stages. Taken together these results provide evidence of a complex interplaying mechanism and highlight the pivotal role of functional related genes. The definition of genes contributing to alternative pathways and their expression profiles corroborates previous hypothesis on mechanisms of accumulation of ascorbate in the later stages of fruit ripening. Results and evidences here provided may facilitate the development of novel strategies for biofortification of tomato fruit with Vitamin C and offer an example framework for similar studies concerning other metabolic pathways and species.
Collapse
Affiliation(s)
- Valentino Ruggieri
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055, Portici, Italy
| | - Hamed Bostan
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055, Portici, Italy
| | - Amalia Barone
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055, Portici, Italy
| | - Luigi Frusciante
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055, Portici, Italy
| | - Maria Luisa Chiusano
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055, Portici, Italy.
| |
Collapse
|
26
|
O'Neill EC, Trick M, Hill L, Rejzek M, Dusi RG, Hamilton CJ, Zimba PV, Henrissat B, Field RA. The transcriptome of Euglena gracilis reveals unexpected metabolic capabilities for carbohydrate and natural product biochemistry. MOLECULAR BIOSYSTEMS 2016; 11:2808-20. [PMID: 26289754 DOI: 10.1039/c5mb00319a] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Euglena gracilis is a highly complex alga belonging to the green plant line that shows characteristics of both plants and animals, while in evolutionary terms it is most closely related to the protozoan parasites Trypanosoma and Leishmania. This well-studied organism has long been known as a rich source of vitamins A, C and E, as well as amino acids that are essential for the human diet. Here we present de novo transcriptome sequencing and preliminary analysis, providing a basis for the molecular and functional genomics studies that will be required to direct metabolic engineering efforts aimed at enhancing the quality and quantity of high value products from E. gracilis. The transcriptome contains over 30,000 protein-encoding genes, supporting metabolic pathways for lipids, amino acids, carbohydrates and vitamins, along with capabilities for polyketide and non-ribosomal peptide biosynthesis. The metabolic and environmental robustness of Euglena is supported by a substantial capacity for responding to biotic and abiotic stress: it has the capacity to deploy three separate pathways for vitamin C (ascorbate) production, as well as producing vitamin E (α-tocopherol) and, in addition to glutathione, the redox-active thiols nor-trypanothione and ovothiol.
Collapse
Affiliation(s)
- Ellis C O'Neill
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Doron L, Segal N, Shapira M. Transgene Expression in Microalgae-From Tools to Applications. FRONTIERS IN PLANT SCIENCE 2016; 7:505. [PMID: 27148328 PMCID: PMC4840263 DOI: 10.3389/fpls.2016.00505] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 03/29/2016] [Indexed: 05/17/2023]
Abstract
Microalgae comprise a biodiverse group of photosynthetic organisms that reside in water sources and sediments. The green microalgae Chlamydomonas reinhardtii was adopted as a useful model organism for studying various physiological systems. Its ability to grow under both photosynthetic and heterotrophic conditions allows efficient growth of non-photosynthetic mutants, making Chlamydomonas a useful genetic tool to study photosynthesis. In addition, this green alga can grow as haploid or diploid cells, similar to yeast, providing a powerful genetic system. As a result, easy and efficient transformation systems have been developed for Chlamydomonas, targeting both the chloroplast and nuclear genomes. Since microalgae comprise a rich repertoire of species that offer variable advantages for biotech and biomed industries, gene transfer technologies were further developed for many microalgae to allow for the expression of foreign proteins of interest. Expressing foreign genes in the chloroplast enables the targeting of foreign DNA to specific sites by homologous recombination. Chloroplast transformation also allows for the introduction of genes encoding several enzymes from a complex pathway, possibly as an operon. Expressing foreign proteins in the chloroplast can also be achieved by introducing the target gene into the nuclear genome, with the protein product bearing a targeting signal that directs import of the transgene-product into the chloroplast, like other endogenous chloroplast proteins. Integration of foreign genes into the nuclear genome is mostly random, resulting in large variability between different clones, such that extensive screening is required. The use of different selection modalities is also described, with special emphasis on the use of herbicides and metabolic markers which are considered to be friendly to the environment, as compared to drug-resistance genes that are commonly used. Finally, despite the development of a wide range of transformation tools and approaches, expression of foreign genes in microalgae suffers from low efficiency. Thus, novel tools have appeared in recent years to deal with this problem. Finally, while C. reinhardtii was traditionally used as a model organism for the development of transformation systems and their subsequent improvement, similar technologies can be adapted for other microalgae that may have higher biotechnological value.
Collapse
|
28
|
O’Neill EC, Trick M, Henrissat B, Field RA. Euglena in time: Evolution, control of central metabolic processes and multi-domain proteins in carbohydrate and natural product biochemistry. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.pisc.2015.07.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
29
|
Zhou B, Peng D, Tan X, Yuan D, Liu X, Zhang L. WITHDRAWN: Expression of Sapium sebiferum (L.) Roxb stearoyl-acyl carrier protein desaturase in Escherichia coli. Protein Expr Purif 2015; 109:127. [DOI: 10.1016/j.pep.2014.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/18/2014] [Accepted: 05/19/2014] [Indexed: 11/30/2022]
|
30
|
Kuivanen J, Penttilä M, Richard P. Metabolic engineering of the fungal D-galacturonate pathway for L-ascorbic acid production. Microb Cell Fact 2015; 14:2. [PMID: 25566698 PMCID: PMC4299797 DOI: 10.1186/s12934-014-0184-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 12/19/2014] [Indexed: 11/29/2022] Open
Abstract
Background Synthetic L-ascorbic acid (vitamin C) is widely used as a preservative and nutrient in food and pharmaceutical industries. In the current production method, D-glucose is converted to L-ascorbic acid via several biochemical and chemical steps. The main source of L-ascorbic acid in human nutrition is plants. Several alternative metabolic pathways for L-ascorbic acid biosynthesis are known in plants. In one of them, D-galacturonic acid is the precursor. D-Galacturonic acid is also the main monomer in pectin, a plant cell wall polysaccharide. Pectin is abundant in biomass and is readily available from several waste streams from fruit and sugar processing industries. Results In the present work, we engineered the filamentous fungus Aspergillus niger for the conversion of D-galacturonic acid to L-ascorbic acid. In the generated pathway, the native D-galacturonate reductase activity was utilized while the gene coding for the second enzyme in the fungal D-galacturonic acid pathway, an L-galactonate consuming dehydratase, was deleted. Two heterologous genes coding for enzymes from the plant L-ascorbic acid pathway – L-galactono-1,4-lactone lactonase from Euglena gracilis (EgALase) and L-galactono-1,4-lactone dehydrogenase from Malpighia glabra (MgGALDH) – were introduced into the A. niger strain. Alternatively, an unspecific L-gulono-1,4-lactone lactonase (smp30) from the animal L-ascorbic acid pathway was introduced in the fungal strain instead of the plant L-galactono-1,4-lactone lactonase. In addition, a strain with the production pathway inducible with D-galacturonic acid was generated by using a bidirectional and D-galacturonic acid inducible promoter from the fungus. Even though, the lactonase enzyme activity was not observed in the resulting strains, they were capable of producing L-ascorbic acid from pure D-galacturonic acid or pectin-rich biomass in a consolidated bioprocess. Product titers up to 170 mg/l were achieved. Conclusions In the current study, an L-ascorbic acid pathway using D-galacturonic acid as a precursor was introduced to a microorganism for the first time. This is also the first report on an engineered filamentous fungus for L-ascorbic acid production and a proof-of-concept of consolidated bioprocess for the production.
Collapse
Affiliation(s)
- Joosu Kuivanen
- VTT Technical Research Centre of Finland, PO Box 1000, 02044 VTT, Espoo, Finland.
| | - Merja Penttilä
- VTT Technical Research Centre of Finland, PO Box 1000, 02044 VTT, Espoo, Finland.
| | - Peter Richard
- VTT Technical Research Centre of Finland, PO Box 1000, 02044 VTT, Espoo, Finland.
| |
Collapse
|
31
|
Aldonolactone oxidoreductases. Methods Mol Biol 2014; 1146:95-111. [PMID: 24764090 DOI: 10.1007/978-1-4939-0452-5_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Vitamin C is a widely used vitamin. Here we review the occurrence and properties of aldonolactone oxidoreductases, an important group of flavoenzymes responsible for the ultimate production of vitamin C and its analogs in animals, plants, and single-cell organisms.
Collapse
|
32
|
Ren J, Chen Z, Duan W, Song X, Liu T, Wang J, Hou X, Li Y. Comparison of ascorbic acid biosynthesis in different tissues of three non-heading Chinese cabbage cultivars. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 73:229-36. [PMID: 24157701 DOI: 10.1016/j.plaphy.2013.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 10/02/2013] [Indexed: 05/26/2023]
Abstract
Ascorbic acid (L-AsA) is an important antioxidant in plants and humans. Vegetables are one of the main sources of ascorbic acid for humans. For instance, non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) is considered as one of the most important vegetables in south China. To elucidate the mechanism by which AsA accumulates, we systematically investigated the expression profiles of D-mannose/L-galactose pathway-related genes. We also investigated the recycling-related genes and AsA contents in different tissues of three non-heading Chinese cabbage cultivars, 'Suzhouqing', 'Wutacai' and 'Erqing' containing different amounts of AsA. Our results showed that six genes [D-mannose-6-phosphate isomerase 1 (PMI1), GDP-L-galactose phosphorylase 1 (GGP1), GGP2, GGP4, GDP-mannose-3', 5'-epimerase1 (GME1), and GME2] were expressed at high level and ascorbate oxidase (AAO) was expressed at low level. This expression pattern contributes, at least partially, to higher AsA accumulation in the leaves and petioles than in the roots. Eight genes (PMI1, GME, GGP, L-galactose-1-phosphate phosphatase, L-galactose dehydrogenase, L-galactono-1, 4-lactone dehydrogenase, monodehydroascorbate reductase 1, and glutathione reductase1) were also expressed at high level; AAO and ascorbate peroxidase (APX) were expressed at low level. This expression pattern may similarly contribute to higher AsA accumulation in 'Wutacai' and 'Suzhouqing' than in 'Erqing'. Therefore, the high expression levels of PMI, GME, and GGP and the low expression level of AAO contributed to the high AsA accumulation in non-heading Chinese cabbage.
Collapse
Affiliation(s)
- Jun Ren
- Horticultural Department, Nanjing Agricultural University, Nanjing 210095, China; State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing 210095, China; Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, China
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Gest N, Gautier H, Stevens R. Ascorbate as seen through plant evolution: the rise of a successful molecule? JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:33-53. [PMID: 23109712 DOI: 10.1093/jxb/ers297] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Ascorbate is a widespread and efficient antioxidant that has multiple functions in plants, traditionally associated with the reactions of photosynthesis. This review aims to look at ascorbate from an evolutionary perspective. Cyanobacteria, algae, and bryophytes contain lower concentrations of ascorbate than higher plants, where the molecule accumulates in high concentrations in both photosynthetic and non-photosynthetic organs and tissues. This increase in ascorbate concentration is paralleled by an increase in the number of isoforms of ascorbate peroxidase and the ascorbate regenerating enzymes mono- and dehydroascorbate reductase. One way of understanding the rise in ascorbate concentrations is to consider ascorbate as a molecule among others that has been subject to selection pressures during evolution, due to its cost or benefit for the cell and the organism. Ascorbate has a low cost in terms of synthesis and toxicity, and its benefits include protection of the glutathione pool and proper functioning of a range of enzymes. The hypothesis presented here is that these features would have favoured increasing roles for the molecule in the development and growth of multicellular organisms. This review then focuses on this diversity of roles for ascorbate in both photosynthetic and non-photosynthetic tissues of higher plants, including fruits and seeds, as well as further functions the molecule may possess by looking at other species. The review also highlights one of the trade-offs of domestication, which has often reduced or diluted ascorbate content in the quest for increased fruit growth and yield, with unknown consequences for the corresponding functional diversity, particularly in terms of stress resistance and adaptive responses to the environment.
Collapse
Affiliation(s)
- Noé Gest
- INRA, UR1052, Génétique et amélioration des fruits et légumes, Domaine St Maurice, 84143 Montfavet, France
| | | | | |
Collapse
|
34
|
Urzica EI, Adler LN, Page MD, Linster CL, Arbing MA, Casero D, Pellegrini M, Merchant SS, Clarke SG. Impact of oxidative stress on ascorbate biosynthesis in Chlamydomonas via regulation of the VTC2 gene encoding a GDP-L-galactose phosphorylase. J Biol Chem 2012; 287:14234-45. [PMID: 22393048 PMCID: PMC3340187 DOI: 10.1074/jbc.m112.341982] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 02/23/2012] [Indexed: 12/30/2022] Open
Abstract
The L-galactose (Smirnoff-Wheeler) pathway represents the major route to L-ascorbic acid (vitamin C) biosynthesis in higher plants. Arabidopsis thaliana VTC2 and its paralogue VTC5 function as GDP-L-galactose phosphorylases converting GDP-L-galactose to L-galactose-1-P, thus catalyzing the first committed step in the biosynthesis of L-ascorbate. Here we report that the L-galactose pathway of ascorbate biosynthesis described in higher plants is conserved in green algae. The Chlamydomonas reinhardtii genome encodes all the enzymes required for vitamin C biosynthesis via the L-galactose pathway. We have characterized recombinant C. reinhardtii VTC2 as an active GDP-L-galactose phosphorylase. C. reinhardtii cells exposed to oxidative stress show increased VTC2 mRNA and L-ascorbate levels. Genes encoding enzymatic components of the ascorbate-glutathione system (e.g. ascorbate peroxidase, manganese superoxide dismutase, and dehydroascorbate reductase) are also up-regulated in response to increased oxidative stress. These results indicate that C. reinhardtii VTC2, like its plant homologs, is a highly regulated enzyme in ascorbate biosynthesis in green algae and that, together with the ascorbate recycling system, the L-galactose pathway represents the major route for providing protective levels of ascorbate in oxidatively stressed algal cells.
Collapse
Affiliation(s)
| | | | | | - Carole L. Linster
- From the Departments of Chemistry and Biochemistry
- the de Duve Institute, Université Catholique de Louvain, BCHM 7539, Ave. Hippocrate 75, B-1200 Brussels, Belgium
| | | | | | - Matteo Pellegrini
- Molecular, Cell, and Developmental Biology, and
- Institute of Genomics and Proteomics
| | - Sabeeha S. Merchant
- From the Departments of Chemistry and Biochemistry
- Institute of Genomics and Proteomics
- Molecular Biology Institute, UCLA, Los Angeles, California 90095 and
| | - Steven G. Clarke
- From the Departments of Chemistry and Biochemistry
- Molecular Biology Institute, UCLA, Los Angeles, California 90095 and
| |
Collapse
|
35
|
Gao Y, Badejo AA, Sawa Y, Ishikawa T. Analysis of two L-Galactono-1,4-lactone-responsive genes with complementary expression during the development of Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2012; 53:592-601. [PMID: 22323769 DOI: 10.1093/pcp/pcs014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Unraveling the role of genes annotated as protein of unknown function is of importance in progression of plant science. l-Galactono-1,4-lactone (l-GalL) is the terminal precursor for ascorbic acid (AsA) biosynthesis in Arabidopsis thaliana, and a previous study showed two DUF (domains of unknown function) 642 family genes (At1g80240 and At5g25460, designated as DGR1 and DGR2, respectively) to be sensitive to it. In this work, leaves from wild-type Arabidopsis were fed with d-glucose, l-galactose, l-GalL and AsA, and the expression level of the At1g80240 and At5g25460 genes showed a specific response to l-GalL, but not to the other supplements despite the increases of the tissue AsA contents. Analysis of promoter-β-glucuronidase (GUS) transgenic plants showed the two genes to be complementarily expressed at the root apex and in the rest of the root excluding the apex, respectively, in both young and old seedlings, and to be expressed at the leaf primordia. The GUS activity under the control of the At5g25460 promoter was high in the cotyledon and leaf veins of young seedlings. These findings were consistent with the results of quantitative real-time PCR. Interestingly, the T-DNA insertion mutant of At5g25460 (SALK_125079) displayed shorter roots and smaller rosettes than Col-0; however, no phenotypic difference was observed between the T-DNA insertion mutant of At1g80240 and the wild type. This is the first report on the expression and functional analysis of these two DUF642 family genes, with the results revealing the contribution of DGR genes to the development of Arabidopsis.
Collapse
Affiliation(s)
- Yongshun Gao
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504 Japan
| | | | | | | |
Collapse
|
36
|
Mellado M, Contreras RA, González A, Dennett G, Moenne A. Copper-induced synthesis of ascorbate, glutathione and phytochelatins in the marine alga Ulva compressa (Chlorophyta). PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2012; 51:102-8. [PMID: 22153245 DOI: 10.1016/j.plaphy.2011.10.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 10/13/2011] [Indexed: 05/20/2023]
Abstract
In order to analyze the synthesis of antioxidant and heavy metal-chelating compounds in response to copper stress, the marine alga Ulva compressa (Chlorophyta) was exposed to 10 μM copper for 7 days and treated with inhibitors of ASC synthesis, lycorine, and GSH synthesis, buthionine sulfoximine (BSO). The levels of ascorbate, in its reduced (ASC) and oxidized (DHA) forms, glutathione, in its reduced (GSH) and oxidized (GSSG) forms, and phytochelatins (PCs) were determined as well as activities of enzymes involved in ASC synthesis, L-galactose dehydrogenase (GDH) and L-galactono 1,4 lactone dehydrogenase (GLDH), and in GSH synthesis, γ-glutamylcysteine synthase (γ-GCS) and glutathione synthase (GS). The level of ASC rapidly decreased to reach a minimum at day 1 that remained low until day 7, DHA decreased until day 1 but slowly increased up to day 7 and its accumulation was inhibited by lycorine. In addition, GSH level increased to reach a maximal level at day 5 and GSSG increased up to day 7 and their accumulation was inhibited by BSO. Activities of GDH and GLDH increased until day 7 and GLDH was inhibited by lycorine. Moreover, activities of γ-GCS and GS increased until day 7 and γ-GCS was inhibited by BSO. Furthermore, PC2, PC3 and PC4, increased until day 7 and their accumulation was inhibited by BSO. Thus, copper induced the synthesis of ascorbate, glutathione and PCs in U. compressa suggesting that these compounds are involved in copper tolerance. Interestingly, U. compressa is, until now, the only ulvophyte showing ASC, GSH and PCs synthesis in response to copper excess.
Collapse
Affiliation(s)
- Macarena Mellado
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | | | | | | | | |
Collapse
|
37
|
Badejo AA, Wada K, Gao Y, Maruta T, Sawa Y, Shigeoka S, Ishikawa T. Translocation and the alternative D-galacturonate pathway contribute to increasing the ascorbate level in ripening tomato fruits together with the D-mannose/L-galactose pathway. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:229-39. [PMID: 21984649 PMCID: PMC3245467 DOI: 10.1093/jxb/err275] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The D-mannose/L-galactose pathway for the biosynthesis of vitamin C (L-ascorbic acid; AsA) has greatly improved the understanding of this indispensable compound in plants, where it plays multifunctional roles. However, it is yet to be proven whether the same pathway holds for all the different organs of plants, especially the fruit-bearing plants, at different stages of development. Micro-Tom was used here to elucidate the mechanisms of AsA accumulation and regulation in tomato fruits. The mRNA expression of the genes in the D-mannose/L-galactose pathway were inversely correlated with increasing AsA content of Micro-Tom fruits during ripening. Feeding L-[6-(14)C]AsA to Micro-Tom plants revealed that the bulk of the label from AsA accumulated in the source leaf was transported to the immature green fruits, and the rate of translocation decreased as ripening progressed. L-Galactose feeding, but neither D-galacturonate nor L-gulono-1,4-lactone, enhanced the content of AsA in immature green fruit. On the other hand, L-galactose and D-galacturonate, but not L-gulono-1,4-lactone, resulted in an increase in the AsA content of red ripened fruits. Crude extract prepared from insoluble fractions of green and red fruits showed D-galacturonate reductase- and aldonolactonase-specific activities, the antepenultimate and penultimate enzymes, respectively, in the D-galacturonate pathway, in both fruits. Taken together, the present findings demonstrated that tomato fruits could switch between different sources for AsA supply depending on their ripening stages. The translocation from source leaves and biosynthesis via the D-mannose/L-galactose pathway are dominant sources in immature fruits, while the alternative D-galacturonate pathway contributes to AsA accumulation in ripened Micro-Tom fruits.
Collapse
Affiliation(s)
- Adebanjo Ayobamidele Badejo
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Keiko Wada
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Yongshun Gao
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Takanori Maruta
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Yoshihiro Sawa
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Shigeru Shigeoka
- Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Takahiro Ishikawa
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
38
|
Cerutti H, Ma X, Msanne J, Repas T. RNA-mediated silencing in Algae: biological roles and tools for analysis of gene function. EUKARYOTIC CELL 2011; 10:1164-72. [PMID: 21803865 PMCID: PMC3187060 DOI: 10.1128/ec.05106-11] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Algae are a large group of aquatic, typically photosynthetic, eukaryotes that include species from very diverse phylogenetic lineages, from those similar to land plants to those related to protist parasites. The recent sequencing of several algal genomes has provided insights into the great complexity of these organisms. Genomic information has also emphasized our lack of knowledge of the functions of many predicted genes, as well as the gene regulatory mechanisms in algae. Core components of the machinery for RNA-mediated silencing show widespread distribution among algal lineages, but they also seem to have been lost entirely from several species with relatively small nuclear genomes. Complex sets of endogenous small RNAs, including candidate microRNAs and small interfering RNAs, have now been identified by high-throughput sequencing in green, red, and brown algae. However, the natural roles of RNA-mediated silencing in algal biology remain poorly understood. Limited evidence suggests that small RNAs may function, in different algae, in defense mechanisms against transposon mobilization, in responses to nutrient deprivation and, possibly, in the regulation of recently evolved developmental processes. From a practical perspective, RNA interference (RNAi) is becoming a promising tool for assessing gene function by sequence-specific knockdown. Transient gene silencing, triggered with exogenously synthesized nucleic acids, and/or stable gene repression, involving genome-integrated transgenes, have been achieved in green algae, diatoms, yellow-green algae, and euglenoids. The development of RNAi technology in conjunction with system level "omics" approaches may provide the tools needed to advance our understanding of algal physiological and metabolic processes.
Collapse
Affiliation(s)
- Heriberto Cerutti
- School of Biological Sciences and Center for Plant Science Innovation, University of Nebraska-Lincoln, E211 Beadle Center, P.O. Box 880666, Lincoln, NE 68588-0666, USA.
| | | | | | | |
Collapse
|
39
|
Euglena gracilis ascorbate peroxidase forms an intramolecular dimeric structure: its unique molecular characterization. Biochem J 2010; 426:125-34. [PMID: 20015051 DOI: 10.1042/bj20091406] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Euglena gracilis lacks a catalase and contains a single APX (ascorbate peroxidase) and enzymes related to the redox cycle of ascorbate in the cytosol. In the present study, a full-length cDNA clone encoding the Euglena APX was isolated and found to contain an open reading frame encoding a protein of 649 amino acids with a calculated molecular mass of 70.5 kDa. Interestingly, the enzyme consisted of two entirely homologous catalytic domains, designated APX-N and APX-C, and an 102 amino acid extension in the N-terminal region, which had a typical class II signal proposed for plastid targeting in Euglena. A computer-assisted analysis indicated a novel protein structure with an intramolecular dimeric structure. The analysis of cell fractionation showed that the APX protein is distributed in the cytosol, but not the plastids, suggesting that Euglena APX becomes mature in the cytosol after processing of the precursor. The kinetics of the recombinant mature FL (full-length)-APX and the APX-N and APX-C domains with ascorbate and H2O2 were almost the same as that of the native enzyme. However, the substrate specificity of the mature FL-APX and the native enzyme was different from that of APX-N and APX-C. The mature FL-APX, but not the truncated forms, could reduce alkyl hydroperoxides, suggesting that the dimeric structure is correlated with substrate recognition. In Euglena cells transfected with double-stranded RNA, the silencing of APX expression resulted in a significant increase in the cellular level of H2O2, indicating the physiological importance of APX to the metabolism of H2O2.
Collapse
|
40
|
Leferink NGH, van Duijn E, Barendregt A, Heck AJR, van Berkel WJH. Galactonolactone dehydrogenase requires a redox-sensitive thiol for optimal production of vitamin C. PLANT PHYSIOLOGY 2009; 150:596-605. [PMID: 19369590 PMCID: PMC2689977 DOI: 10.1104/pp.109.136929] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 04/09/2009] [Indexed: 05/18/2023]
Abstract
The mitochondrial flavoenzyme l-galactono-gamma-lactone dehydrogenase (GALDH) catalyzes the ultimate step of vitamin C biosynthesis in plants. We found that recombinant GALDH from Arabidopsis (Arabidopsis thaliana) is inactivated by hydrogen peroxide due to selective oxidation of cysteine (Cys)-340, located in the cap domain. Electrospray ionization mass spectrometry revealed that the partial reversible oxidative modification of Cys-340 involves the sequential formation of sulfenic, sulfinic, and sulfonic acid states. S-Glutathionylation of the sulfenic acid switches off GALDH activity and protects the enzyme against oxidative damage in vitro. C340A and C340S GALDH variants are insensitive toward thiol oxidation, but exhibit a poor affinity for l-galactono-1,4-lactone. Cys-340 is buried beneath the protein surface and its estimated pK(a) of 6.5 suggests the involvement of the thiolate anion in substrate recognition. The indispensability of a redox-sensitive thiol provides a rationale why GALDH was designed as a dehydrogenase and not, like related aldonolactone oxidoreductases, as an oxidase.
Collapse
Affiliation(s)
- Nicole G H Leferink
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | | | | | | | | |
Collapse
|