Yeast cell factories have been increasingly employed for producing plant‐derived natural products. Unfortunately, the stability of plant natural product biosynthetic pathway genes, particularly when driven by the same sets of promoters and terminators, remains one of the biggest concerns for synthetic biology. Here we profile genomic loci flanked by essential genes as stable integration sites in a genome‐wide manner, for stable maintenance of multigene biosynthetic pathways in yeast. We demonstrate the application of our yeast integration platform in the construction of sanguinarine (24 expression cassettes) and ajmalicine (29 expression cassettes) de novo biosynthetic pathways for the first time. Moreover, we establish stable yeast cell factories that can produce 119.2 mg L−1 heteroyohimbine alkaloids (containing 61.4 mg L−1 ajmalicine) in shake flasks, representing the highest titer of monoterpene indole alkaloids (MIAs) ever reported and promising the complete biosynthesis of other high‐value MIAs (such as vinblastine) for biotechnological applications.

Vindoline is a plant derived monoterpene indole alkaloid (MIA) with potential therapeutic applications and more importantly serves as the precursor to vinblastine and vincristine. To obtain a yeast strain for high yield production of vindoline from tabersonine, multiple metabolic engineering strategies were employed via the CRISPR/Cas9 mediated multiplex genome integration technology in the present study. Through increasing and tuning the copy numbers of the pathway genes, pairing cytochrome P450 enzymes (CYPs) with appropriate cytochrome P450 reductases (CPRs), engineering the microenvironment for functional expression of CYPs, enhancing cofactor supply, and optimizing fermentation conditions, the production of vindoline was increased to a final titer as high as ∼16.5 mg/L, which is more than 3,800,000-fold higher than the parent strain and the highest tabersonine to vindoline conversion yield ever reported. This work represents a key step of the engineering efforts to establish de novo biosynthetic pathways for vindoline, vinblastine, and vincristine.

Vinblastine has been used clinically as one of the most potent therapeutics for the treatment of several types of cancer. However, the traditional plant extraction method suffers from unreliable supply, low abundance, and extremely high cost. Here, we use synthetic biology approach to engineer Saccharomyces cerevisiae for de novo biosynthesis of vindoline and catharanthine, which can be coupled chemically or biologically to vinblastine. On the basis of a platform strain with sufficient supply of precursors and cofactors for biosynthesis, we reconstituted, debottlenecked, and optimized the biosynthetic pathways for the production of vindoline and catharanthine. The vindoline biosynthetic pathway represents one of the most complicated pathways ever reconstituted in microbial cell factories. Using shake flask fermentation, our engineered yeast strains were able to produce catharanthine and vindoline at a titer of 527.1 and 305.1 μg·liter −1 , respectively, without accumulating detectable amount of pathway intermediates. This study establishes a representative example for the production of valuable plant natural products in yeast.

No abstract