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Bioengineering Approach on Terpenoids Production
Published in Dijendra Nath Roy, Terpenoids Against Human Diseases, 2019
The availability of precursors for the formation of a certain metabolite is central to any bioengineering effort. In the case of plant terpenoids, two spatially separated pathways—the MEP and MVA pathways—are responsible for the generation of IPP and DMAPP: the universal precursors of all terpenoids. In some cases, metabolic cross talk is also known to exist between these two pathways (Hemmerlin et al. 2003) which can vary among plants. Many studies have been reported that have manipulated important MEP and MVA pathway genes for terpenoid bioengineering. However, the concentration of which precursor intermediate of these pathways becomes rate limiting for terpenoid production differs from plant to plant. The MEP pathway consists of seven enzymatic reactions leading to the formation of IPP and DMAPP, and many pathway enzymes are encoded by small gene families. The first step is catalysed by 1-deoxy-d-xylulose-5-phosphate (DXP) synthase (DXS), which is presumed to be the main rate-limiting enzyme controlling the plastidial pool of IPP. In view of this, overexpression of DXS in many plants leads to the increased accumulation of various plastidial isoprenoids such as chlorophylls, tocopherols, carotenoids, abscisic acid and gibberellins (Estevez et al. 2001; Simpson et al. 2016). However, DXS overexpression does not result in increased yield of terpenoids in the peppermint plant (Lange et al. 2011). In the second step of the MEP pathway, the DXP reductoisomerase (DXR) enzyme synthesizes methylerythritol phosphate from DXS (Julliard and Douce 1991; Sprenger et al. 1997). Overexpression of DXS genes enhances levels of terpenoids in many plants, but in some cases, it has no effect (Simpson et al. 2016). For example, up-regulation of DXR in peppermint (Mentha × piperita) enhanced the flux towards increased monoterpenoid production, leading to a 50% increase in essential oil yield. Nevertheless, DXR overexpression in spike lavender (Lavandula latifolia) has no effect on essential oil formation (Mendoza-Poudereux et al. 2014). Botella-Pavía et al. (2004) reported hydroxymethylbutenyl diphosphate reductase (HDR), catalysing the last step for IPP and DMAPP production in the MEP pathway, as a rate-limiting enzyme in the tomato (Lycopersicon esculentum) and Arabidopsis. In view of this finding, the generation of transgenic plants of Arabidopsis overexpressing taxadiene synthase and either HDR or DXS has resulted in increased taxadiene levels (Botella-Pavía et al. 2004).
Engineered production of pyridoxal 5′-phosphate in Escherichia coli BL21
Published in Preparative Biochemistry & Biotechnology, 2022
Min He, Jian Ma, Qingwei Chen, Qili Zhang, Ping Yu
The two basic routes for de novo biosynthesis of PLP in organisms are 1-deoxy-D-xylulose-5-phosphate (DXP)—a dependent pathway and DXP-independent pathway.[18] The DXP-independent pathway exists in all vitamin B6 autotrophic organisms and is the dominant PLP synthesis route. The DXP-dependent pathway only exists in Escherichia coli and a few bacteria.[19] In the DXP-dependent pathway, DXP is derived from glyceraldehyde 3-phosphate (GAP) and pyruvate by the action of DXP synthase.[20,21] Pyridolol 5′-phosphate (PNP) was first synthesized from DXP and 4-phosphate hydroxythreonine by 4-hydroxythreonine 4-phosphate dehydrogenase (PDXA), pyridine 5′-phosphate synthase (PDXJ), and 1-deoxyxylose 5-phosphate synthase (DXS).[22–24] Pyridolol 5′-phosphate (PNP) is the direct precursor of the biosynthesis of the ubiquitous and essential coenzyme PLP.[25,26] It is oxidized to PLP by the pyridoxine 5′-phosphate oxidase (PDXH) for cell metabolism in E. coli.[27–29]