Metabolic engineering for precursor balancing to enhance isoprenoids production in Escherichia coli

Abstract

Biosynthesis of isoprenoids via DXP pathway requires equimolar of glyceraldehyde 3-phosphate and pyruvate to divert carbon flux towards products of interest. Here, I demonstrate the precursor balancing is one of the critical steps for the production of isoprenoids in Escherichia coli. First of all, the implementation of synthetic lycopene production pathway as a model system and amplification of native DXP pathway was accomplished using synthetic constitutive promoters and redesigned 5`-untranslated regions (5`-UTRs). Next, fine-controlled precursor balancing was searched by tuning phosphoenolpyruvate synthase (PpsA) or glyceraldehyde 3-phosphate dehydrogenase (GAPDH). The results showed that tuning-down of gapA improved 46% of specific lycopene contents (14.38 mg/g DCW) than the overexpression of ppsA (9.83 mg/g DCW), which increased 96% and 38% compared to parental strain, respectively. To our best of knowledge, gapA never been explored for precursor balancing to increase biosynthesis of isoprenoids. Therefore, our approach provides a novel engineering target for precursor balancing that could be broadly exploited to enhance production of numerous high-value isoprenoids.