Dokument: The Role of Organellar Transporters in C3/C4-Metabolism
| Titel: | The Role of Organellar Transporters in C3/C4-Metabolism | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=54267 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20200924-112254-7 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Kuhnert, Franziska [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Weber, Andreas P. M. [Gutachter] Prof. Dr. Westhoff, Peter [Gutachter] | |||||||
| Stichwörter: | Photorespiration, C4 Photosynthesis, Mitochondria, Transporter | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 580 Pflanzen (Botanik) | |||||||
| Beschreibung: | Subcellular compartmentalization enabled both pro- and eukaryotic organisms to target metabolic reactions into distinct organelles differing in their pH, redox state as well as metabolite- and protein content. Thus, spatial separation of entire pathways is enabled which in turn translates into new opportunities for regulatory finetuning of metabolic processes. To ensure metabolite flow within the metabolic network of the cell, organellar membranes contain pores, channels and transporters. In vivo analyses of transport proteins are challenging due to their low abundance and the frequent necessity to isolate intact organelles. To overcome these limitations, we adapted a rapid isolation technique for plant mitochondria (Manuscript I). We showed that respiratory active mitochondria from root, leaves or seedling tissues can be isolated within 25 minutes from as little as one gram of starting material with sufficient yields. Isolated mitochondria are pure and suitable for proteomics and enzymatic analyses. Optimization of our technique and application to other cell compartments will contribute to ongoing research about metabolite content, redox state and the role of transport proteins of different cellular compartments.
A prime example of a metabolically highly interconnected process is photorespiration. The photorespiratory pathway is a consequence of the oxygenase reaction of Rubisco and takes place in all organisms performing oxygenic photosynthesis. It relies on shuttling of intermediates between chloroplasts, peroxisomes, mitochondria and the cytosol. The photorespiratory pathway has been intensively studied during the last couple of decades, resulting in a comprehensive knowledge of its soluble enzymes. However, only few transport proteins have been identified so far. Recently, the mitochondrial carrier protein À BOUT DE SOUFFLE (BOU) has been described as a mitochondrial glutamate transporter. Knockout of BOU results in a strong photorespiratory phenotype, demonstrating its importance within the photorespiratory pathway. However, its physiological role remained enigmatic to date. Biochemical analyses of recombinant BOU and intact bou-2 mitochondria revealed that BOU is a key regulator of nitrogen re-assimilation during photorespiration (Manuscript II). To overcome the limitations caused by photorespiration some plants evolved a specialized mechanism to concentrate CO2 at the site of Rubisco, known as C4 photosynthesis. This adaptation reduces the rate of photorespiration and increases photosynthetic efficiency. However, the amount of transport steps per fixed molecule CO2 increased from only one in C3 to at least ten in C4 species. We analyzed the role of the plastidic BILE ACID SODIUM SYMPORTER 4 (BASS4) from the C4 species Flaveria bidentis. BASS4 was previously identified in comparative transcriptomics analyses as a candidate transporter involved in C4 photosynthesis. We found that BASS4 is a malate transporter with a clearly defined substrate spectrum that catalyzes sodium-driven malate symport in vitro (Manuscript III). Moreover, our results emphasize a crucial role of BASS4 within the C4 pathway and suggest a novel malate transport system within the NADP-dependent malic enzyme subtype. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Biologie » Biochemie der Pflanzen | |||||||
| Dokument erstellt am: | 24.09.2020 | |||||||
| Dateien geändert am: | 24.09.2020 | |||||||
| Promotionsantrag am: | 04.03.2020 | |||||||
| Datum der Promotion: | 08.06.2020 |
