Effect of isopentenyl pyrophosphate translocation on the biosynthesis of triptolide / 生物工程学报

Triptolide has wide clinical applications due to its anti-inflammatory, anti-tumor and immunosuppressive activities. In this study, we investigated the effect of blocking isopentenyl pyrophosphate (IPP) translocation on the biosynthesis of triptolide by exogenously adding D,L-glyceraldehyde (DLG) to the suspension cells of Ttripterygium wilfordii at different stages (7 d, 14 d). Subsequently, the cell viability, biomass accumulation, triptolide contents, as well as the profiles of the key enzyme genes involved in the upstream pathway of triptolide biosynthesis, were analyzed. The results showed that IPP translocation is involved in the biosynthesis of triptolide. IPP is mainly translocated from the plastid (containing the MEP pathway) to the cytoplasm (containing the MVA pathway) in the early stage of the culture, but reversed in the late stage. Blocking the translocation of IPP affected the expression of key enzyme genes involved in the upstream pathway of triptolide, which in turn affected the accumulation of triptolide. Understanding the characteristics and mechanism of IPP translocation provides a theoretical basis for further promoting triptolide biosynthesis through synthetic biology.

Metabolic engineering of chloroplasts for artemisinic acid biosynthesis and impact on plant growth.

Chloroplasts offer high-level transgene expression and transgene containment due to maternal inheritance, and are ideal hosts for biopharmaceutical biosynthesis via multigene engineering. To exploit these advantages, we have expressed 12 enzymes in chloroplasts for the biosynthesis of artemisinic acid (precursor of artemisinin, antimalarial drug) in an alternative plant system. Integration of transgenes into the tobacco chloroplast genome via homologous recombination was confirmed by molecular analysis, and biosynthesis of artemisinic acid in plant leaf tissues was detected with the help of 13C NMR and ESI-mass spectrometry. The excess metabolic flux of isopentenyl pyrophosphate generated by an engineered mevalonate pathway was diverted for the biosynthesis of artemisinic acid. However, expression of megatransgenes impacted the growth of the transplastomic plantlets. By combining two exogenous pathways, artemisinic acid was produced in transplastomic plants, which can be improved further using better metabolic engineering strategies for commercially viable yield of desirable isoprenoid products.