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- Gene-guided discovery and engineering of branched cyclic peptides in plants
- Enzyme Fusion Removes Competition for Geranylgeranyl Diphosphate in Carotenogenesis
- Neopinone isomerase is involved in codeine and morphine biosynthesis in opium poppy
- Computational Approaches to Design and Test Plant Synthetic Metabolic Pathways
- Changing Form and Function through Carotenoids and Synthetic Biology
- Unleashing the Synthetic Power of Plant Oxygenases: From Mechanism to Application
- Parts-Prospecting for a High-Efficiency Thiamin Thiazole Biosynthesis Pathway
- Engineering of plastids to optimize the production of high-value metabolites and proteins
- Computational approaches to design and test plant synthetic metabolic pathways
- Improving the efficiency of photosynthetic carbon reactions
- Engineering of metabolic pathways using synthetic enzyme complexes
- Synthetic metabolic pathways for photobiological conversion of CO2 into hydrocarbon fuel
- Molecular Plant: Special Issue on Plant Metabolism and Synthetic Biology (2014)
Enzyme Fusion Removes Competition for Geranylgeranyl Diphosphate in Carotenogenesis
- © 2019 American Society of Plant Biologists. All rights reserved.
Geranylgeranyl diphosphate (GGPP), a prenyl diphosphate synthesized by GGPP synthase (GGPS), represents a metabolic hub for the synthesis of key isoprenoids, such as chlorophylls, tocopherols, phylloquinone, gibberellins, and carotenoids. Protein-protein interactions and the amphipathic nature of GGPP suggest metabolite channeling and/or competition for GGPP among enzymes that function in independent branches of the isoprenoid pathway. To investigate substrate conversion efficiency between the plastid-localized GGPS isoform GGPS11 and phytoene synthase (PSY), the first enzyme of the carotenoid pathway, we used recombinant enzymes and determined their in vitro properties. Efficient phytoene biosynthesis via PSY strictly depended on simultaneous GGPP supply via GGPS11. In contrast, PSY could not access freely diffusible GGPP or time-displaced GGPP supply via GGPS11, presumably due to liposomal sequestration. To optimize phytoene biosynthesis, we applied a synthetic biology approach and constructed a chimeric GGPS11-PSY metabolon (PYGG). PYGG converted GGPP to phytoene almost quantitatively in vitro and did not show the GGPP leakage typical of the individual enzymes. PYGG expression in Arabidopsis resulted in orange-colored cotyledons, which are not observed if PSY or GGPS11 are overexpressed individually. This suggests insufficient GGPP substrate availability for chlorophyll biosynthesis achieved through GGPP flux redirection to carotenogenesis. Similarly, carotenoid levels in PYGG-expressing callus exceeded that in PSY- or GGPS11-overexpression lines. The PYGG chimeric protein may assist in provitamin A biofortification of edible plant parts. Moreover, other GGPS fusions may be used to redirect metabolic flux into the synthesis of other isoprenoids of nutritional and industrial interest.
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