1P-386 : Improved isoprenoids production by precursor rebalancing using precise control of gapA expression in Escherichia coli

Biosynthesis of isoprenoids via the DXP pathway requires equimolar glyceraldehyde 3-phosphate and pyruvate to divert carbon flux toward the products of interest. Here, we demonstrate that precursor balancing is one of the critical steps for the production of isoprenoids in E. coli. First, the implementation of the synthetic lycopene production pathway as a model system and the amplification of the native DXP pathway were accomplished using synthetic promoters and redesigned 5'-UTR. Next, fine-controlled precursor balancing was investigated by tuning phosphoenolpyruvate synthase (PpsA) or glyceraldehyde 3-phosphate dehydrogenase (GAPDH). The results showed that tuning-down of gapA improved the specific lycopene content by 46% compared to the overexpression of ppsA. The lycopene in the strains with down-regulated gapA increased by 96% compared to that in the parental strain. Our results indicate that gapA is the best target for precursor balancing to increase biosynthesis of isoprenoids.