Identification of CYP82E21 as a functional nicotine N-demethylase in tobacco flowers
| Autor: | Gerhard Lang, Simon Goepfert, Aline Vuarnoz, Helene Laparra, Joanne Schwaar, Nicolas Sierro, Verena Liedschulte, Lucien Bovet, Berangere Philippon, Nicolas Bakaher |
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| Jazyk: | angličtina |
| Předmět: |
0106 biological sciences
0301 basic medicine Nicotine Nornicotine Nitrosamines Nicotiana tabacum Flowers Plant Science Horticulture 01 natural sciences Biochemistry Nicotine conversion 03 medical and health sciences chemistry.chemical_compound Cytochrome P-450 Enzyme System Expression study RNA interference Tobacco medicine Molecular Biology Gene Solanaceae Plant Proteins biology fungi food and beverages Oxidoreductases N-Demethylating General Medicine Nicotine N-demethylase biology.organism_classification Nornicotine biosynthesis Plant Leaves 030104 developmental biology chemistry Nicotiana tomentosiformis biology.protein Demethylase RNA Interference Ectopic expression Gene function 010606 plant biology & botany medicine.drug |
| Zdroj: | Phytochemistry. :9-16 |
| ISSN: | 0031-9422 |
| DOI: | 10.1016/j.phytochem.2016.08.004 |
| Popis: | In the tobacco plant, nicotine N-demethylase enzymes (NND) belonging to the cytochrome P450 family catalyse the conversion of nicotine to nornicotine, the precursor of the carcinogenic tobacco-specific N-nitrosamine, N-nitrosonornicotine. To date three demethylase genes, namely CYP82E4, CYP82E5 and CYP82E10, have been shown to be involved in this process, while the related CYP82E2 and CYP82E3 genes are not functional. We have identified a further gene named CYP82E21 encoding a putative nicotine N-demethylase closely related to the CYP82E genes. The CYP82E21 gene was found in all Nicotiana tabacum cultivars analysed and originates from the tobacco ancestor Nicotiana tomentosiformis. We show that, in contrast to all other previously characterized NND genes, CYP82E21 is not expressed in green or senescent leaves, but in flowers, more specifically in ovaries. The nicotine N-demethylase activity of CYP82E21 was confirmed by ectopic expression of the coding sequence in a tobacco line lacking functional CYP82E4, CYP82E5 and CYP82E10 genes, resulting in an eightfold increase of nicotine demethylation compared to the control plants. Furthermore, nornicotine formation can be reduced in ovaries by introducing a CYP82E21-specific RNAi construct. Together, our results demonstrate that the CYP82E21 gene encodes a functional ovary-specific nicotine N-demethylase. |
| Databáze: | OpenAIRE |
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