This article describes the reconstitution of the early paclitaxel biosynthetic pathway in Nicotiana benthamiana. Paclitaxel, a cancer drug derived from the yew tree, is synthesized through a complex pathway involving multiple enzymes. A major challenge in reconstituting this pathway has been the promiscuous activity of the cytochrome P450 enzyme taxadiene 5α-hydroxylase (T5αH), which produces multiple oxidized products. By tuning the expression level of T5αH using a weaker promoter, the researchers were able to reduce the formation of these byproducts and increase the accumulation of taxadien-5α-ol, a key precursor to paclitaxel. This allowed the reconstitution of a six-step biosynthetic pathway, which was further shown to function as a metabolic network. The study demonstrates that six previously characterized Taxus genes can coordinatively produce key paclitaxel intermediates and serves as a crucial platform for the discovery of the remaining biosynthetic genes. The results highlight the importance of understanding the biosynthetic pathway for the development of sustainable production methods for paclitaxel. The study also provides structural characterization of four new oxidized taxadiene products from T5αH, which may have implications for the understanding of paclitaxel biosynthesis. The findings contribute to the broader understanding of plant secondary metabolism and the potential for metabolic engineering in the production of valuable natural products.This article describes the reconstitution of the early paclitaxel biosynthetic pathway in Nicotiana benthamiana. Paclitaxel, a cancer drug derived from the yew tree, is synthesized through a complex pathway involving multiple enzymes. A major challenge in reconstituting this pathway has been the promiscuous activity of the cytochrome P450 enzyme taxadiene 5α-hydroxylase (T5αH), which produces multiple oxidized products. By tuning the expression level of T5αH using a weaker promoter, the researchers were able to reduce the formation of these byproducts and increase the accumulation of taxadien-5α-ol, a key precursor to paclitaxel. This allowed the reconstitution of a six-step biosynthetic pathway, which was further shown to function as a metabolic network. The study demonstrates that six previously characterized Taxus genes can coordinatively produce key paclitaxel intermediates and serves as a crucial platform for the discovery of the remaining biosynthetic genes. The results highlight the importance of understanding the biosynthetic pathway for the development of sustainable production methods for paclitaxel. The study also provides structural characterization of four new oxidized taxadiene products from T5αH, which may have implications for the understanding of paclitaxel biosynthesis. The findings contribute to the broader understanding of plant secondary metabolism and the potential for metabolic engineering in the production of valuable natural products.