Engineering Escherichia coli to improve tryptophan production via genetic manipulation of precursor and cofactor pathways

Synthetic and Systems Biotechnology
Zhu LiDawei Zhang

Abstract

Optimizing the supply of biosynthetic precursors and cofactors is usually an effective metabolic strategy to improve the production of target compounds. Here, the combination of optimizing precursor synthesis and balancing cofactor metabolism was adopted to improve tryptophan production in Escherichia coli. First, glutamine synthesis was improved by expressing heterologous glutamine synthetase from Bacillus subtilis and Bacillus megaterium in the engineered Escherichia coli strain KW001, resulting in the best candidate strain TS-1. Then icd and gdhA were overexpressed in TS-1, which led to the accumulation of 1.060 g/L tryptophan. Subsequently, one more copy of prs was introduced on the chromosome to increase the flux of 5-phospho-α-d-ribose 1-diphosphate followed by the expression of mutated serA and thrA to increase the precursor supply of serine, resulting in the accumulation of 1.380 g/L tryptophan. Finally, to maintain cofactor balance, sthA and pntAB, encoding transhydrogenase, were overexpressed. With sufficient amounts of precursors and balanced cofactors, the engineered strain could produce 1.710 g/L tryptophan after 48 h of shake-flask fermentation, which was 2.76-times higher than the titer of the parent strain. Take...Continue Reading

Citations

Feb 6, 2021·Journal of Agricultural and Food Chemistry·Hongxuan WuFeng Qi
Sep 15, 2021·Bioprocess and Biosystems Engineering·Kristin SchoppelDirk Weuster-Botz

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Methods Mentioned

BETA
phosphotransferase
PCR

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