A 7-Deoxyloganetic Acid Glucosyltransferase Contributes a Key Step in Secologanin Biosynthesis in Madagascar Periwinkle
| Autor: | Vincenzo De Luca, Elizabeth Edmunds, Kazuyoshi Terasaka, Keisuke Asada, Sayaka Masada-Atsumi, Hajime Mizukami, Mai Nagatoshi, Vonny Salim |
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| Rok vydání: | 2013 |
| Předmět: |
Iridoid
Catharanthus medicine.drug_class Iridoid Glucosides Molecular Sequence Data Plant Science Phloem Molecular cloning chemistry.chemical_compound Biosynthesis Botany medicine Gene Silencing Cloning Molecular Gene Phylogeny Research Articles Plant Proteins biology fungi food and beverages Cell Biology Catharanthus roseus biology.organism_classification Secologanin Tryptamine Alkaloids Biochemistry chemistry Glucosyltransferases biology.protein Glucosyltransferase Secologanin |
| Zdroj: | The Plant Cell. 25:4123-4134 |
| ISSN: | 1532-298X 1040-4651 |
| DOI: | 10.1105/tpc.113.115154 |
| Popis: | Iridoids form a broad and versatile class of biologically active molecules found in thousands of plant species. In addition to the many hundreds of iridoids occurring in plants, some iridoids, such as secologanin, serve as key building blocks in the biosynthesis of thousands of monoterpene indole alkaloids (MIAs) and many quinoline alkaloids. This study describes the molecular cloning and functional characterization of three iridoid glucosyltransfeases (UDP-SUGAR GLYCOSYLTRANSFERASE6 [UGT6], UGT7, and UGT8) from Madagascar periwinkle (Catharanthus roseus) with remarkably different catalytic efficiencies. Biochemical analyses reveal that UGT8 possessed a high catalytic efficiency toward its exclusive iridoid substrate, 7-deoxyloganetic acid, making it better suited for the biosynthesis of iridoids in periwinkle than the other two iridoid glucosyltransfeases. The role of UGT8 in the fourth to last step in secologanin biosynthesis was confirmed by virus-induced gene silencing in periwinkle plants, which reduced expression of this gene and resulted in a large decline in secologanin and MIA accumulation within silenced plants. Localization studies of UGT8 using a carborundum abrasion method for RNA extraction show that its expression occurs preferentially within periwinkle leaves rather than in epidermal cells, and in situ hybridization studies confirm that UGT8 is preferentially expressed in internal phloem associated parenchyma cells of periwinkle species. |
| Databáze: | OpenAIRE |
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