Engineering a Balanced Mevalonate Pathway in E.coli

In the present study we showed two different approaches for balancing heterologous MEV gene expression in E.coli and improve production from 1% glucose: i) Engineer a dynamic regulation of the pathway using promoters responding to an accumulation of the toxic intermediate FPP, which improved bisabolene titer to 875 mg/L ii) Explore expression of the MEV pathway enzymes using targeted proteomics and its associated limonene production to define engineering strategies; a principal component analysis (PCA) of the proteomics and the production at various conditions suggests that an over-expression of the bottom portion of the pathway and a moderate expression of the top portion are keys to improve the production. Indeed, extra copies of the terpene synthase and a modified top portion led to 665 mg/L and 1150 mg/L of limonene and bisabolene productions, respectively. This represents a 40% increase in production titer over previous, unbalanced systems using the same genes.