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Inwongwan S, Kruger NJ, Ratcliffe RG, O'Neill EC. Euglena Central Metabolic Pathways and Their Subcellular Locations. Metabolites 2019; 9:E115. [PMID: 31207935 PMCID: PMC6630311 DOI: 10.3390/metabo9060115] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/03/2019] [Accepted: 06/11/2019] [Indexed: 01/16/2023] Open
Abstract
Euglenids are a group of algae of great interest for biotechnology, with a large and complex metabolic capability. To study the metabolic network, it is necessary to know where the component enzymes are in the cell, but despite a long history of research into Euglena, the subcellular locations of many major pathways are only poorly defined. Euglena is phylogenetically distant from other commonly studied algae, they have secondary plastids bounded by three membranes, and they can survive after destruction of their plastids. These unusual features make it difficult to assume that the subcellular organization of the metabolic network will be equivalent to that of other photosynthetic organisms. We analysed bioinformatic, biochemical, and proteomic information from a variety of sources to assess the subcellular location of the enzymes of the central metabolic pathways, and we use these assignments to propose a model of the metabolic network of Euglena. Other than photosynthesis, all major pathways present in the chloroplast are also present elsewhere in the cell. Our model demonstrates how Euglena can synthesise all the metabolites required for growth from simple carbon inputs, and can survive in the absence of chloroplasts.
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Affiliation(s)
- Sahutchai Inwongwan
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
| | - Nicholas J Kruger
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
| | - R George Ratcliffe
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
| | - Ellis C O'Neill
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
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Nakazawa M, Hayashi R, Takenaka S, Inui H, Ishikawa T, Ueda M, Sakamoto T, Nakano Y, Miyatake K. Physiological functions of pyruvate:NADP + oxidoreductase and 2-oxoglutarate decarboxylase in Euglena gracilis under aerobic and anaerobic conditions. Biosci Biotechnol Biochem 2017; 81:1386-1393. [PMID: 28463550 DOI: 10.1080/09168451.2017.1318696] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
In Euglena gracilis, pyruvate:NADP+ oxidoreductase, in addition to the pyruvate dehydrogenase complex, functions for the oxidative decarboxylation of pyruvate in the mitochondria. Furthermore, the 2-oxoglutarate dehydrogenase complex is absent, and instead 2-oxoglutarate decarboxylase is found in the mitochondria. To elucidate the central carbon and energy metabolisms in Euglena under aerobic and anaerobic conditions, physiological significances of these enzymes involved in 2-oxoacid metabolism were examined by gene silencing experiments. The pyruvate dehydrogenase complex was indispensable for aerobic cell growth in a glucose medium, although its activity was less than 1% of that of pyruvate:NADP+ oxidoreductase. In contrast, pyruvate:NADP+ oxidoreductase was only involved in the anaerobic energy metabolism (wax ester fermentation). Aerobic cell growth was almost completely suppressed when the 2-oxoglutarate decarboxylase gene was silenced, suggesting that the tricarboxylic acid cycle is modified in Euglena and 2-oxoglutarate decarboxylase takes the place of the 2-oxoglutarate dehydrogenase complex in the aerobic respiratory metabolism.
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Affiliation(s)
- Masami Nakazawa
- a Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences , Osaka Prefecture University , Sakai , Japan.,b Core Research for Evolutional Science and Technology (CREST) , Japan Science and Technology Agency (JST) , Kawaguchi , Japan
| | - Ryuta Hayashi
- a Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences , Osaka Prefecture University , Sakai , Japan
| | - Shigeo Takenaka
- c Division of Veterinary Sciences, Graduate School of Life and Environmental Sciences , Osaka Prefecture University , Izumisano , Japan
| | - Hiroshi Inui
- b Core Research for Evolutional Science and Technology (CREST) , Japan Science and Technology Agency (JST) , Kawaguchi , Japan.,d Department of Nutrition, College of Health and Human Sciences , Osaka Prefecture University , Habikino , Japan
| | - Takahiro Ishikawa
- b Core Research for Evolutional Science and Technology (CREST) , Japan Science and Technology Agency (JST) , Kawaguchi , Japan.,e Faculty of Life and Environmental Science, Department of Life Science and Biotechnology , Shimane University , Matsue , Japan
| | - Mitsuhiro Ueda
- a Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences , Osaka Prefecture University , Sakai , Japan
| | - Tatsuji Sakamoto
- a Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences , Osaka Prefecture University , Sakai , Japan
| | - Yoshihisa Nakano
- a Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences , Osaka Prefecture University , Sakai , Japan
| | - Kazutaka Miyatake
- f Faculty of Human and Cultural Studies, Department of Nutrition and Food Sciences , Tezukayama Gakuin University , Sakai , Japan
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Abstract
The biochemistry of zinc has come under intensive investigation at the molecular level during the past 20 years. More than 70 zinc metalloenzymes are now known, and they span a broad range of biologic activities. Substitution of zinc by cobalt, for example, serves to locate a paramagnetic probe at the active site of the enzyme which can then provide information regarding the coordination properties of the metal and the active site environment.
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