Engineering Metabolic Pathways for Cofactor Self-Sufficiency and Serotonin Production in Escherichia coli

Abstract

Serotonin is a neurotransmitter that plays an essential regulatory role in numerous cognitive and behavioral functions. Recent advances in synthetic biology have enabled engineering of non-natural biosynthetic pathways for serotonin production in E. coli. Here, an optimized heterologous serotonin biosynthetic pathway was engineered in E. coli and coupled with the biosynthetic and regeneration modules of the endogenous vital cofactor tetrahydrobiopterin (BH4) for efficient serotonin production using whole-cell catalysis. Further metabolic engineering efforts were performed to ensure an adequate endogenous BH4 supply, including enhancements of GTP biosynthesis and intracellular reducing power availability. Using the optimized fed-batch fermentation, an overall maximum serotonin yield of 40.3% (mol/mol) and a peak titer of 1.68 g/L (production rate of 0.016 g/L/h) were achieved. The strategies employed in this study show the promise of using E. coli for pterin self-sufficiency and high-level serotonin production, and the engineered strains hold the potential for use in industrial applications.

Integrated and Enhanced Coassimilation of Formate and Acetate for Efficient Utilization of Lignocellulosic Hydrolysate

“…The CRISPR/Cas9-based procedures for genomic editing were primarily derived from the previously reported methods. , Through constructing the plasmids pTargetF- RCpck , pTargetF- ECpck, and pTargetF- ASpck , the genes for RCpck , ECpck , and ASpck were respectively integrated into the sdaB (encoding l -serine deaminase 2) site of the E. coli MG1655 genome and expressed under their respective constitutive tac promoters, resulting in the recombinant strain MRPK, MEPK, and MAPK.…”

“…The CRISPR/Cas9-based procedures for genomic editing were primarily derived from the previously reported methods. 20,23 Through constructing the plasmids pTargetF-RCpck, pTargetF-ECpck, and pTargetF-ASpck, the genes for RCpck, ECpck, and ASpck were respectively integrated into the sdaB (encoding L-serine deaminase 2) site of the E. coli MG1655 genome and expressed under their respective constitutive tac promoters, resulting in the recombinant strain MRPK, MEPK, and MAPK. In addition, gltA coding for citrate synthase and icd coding for isocitrate dehydrogenase were integrated into the chromosome of MG1655 by replacing the genes of aceK (encoding isocitrate dehydrogenase kinase/phosphatase) and adhE (encoding acetaldehyde dehydrogenase), respectively, obtaining the recombinant strains MGAG and MGAI.…”

Development of Biochar-Based Whole-Cell Biocatalysts for the Production of l-Tryptophan and l-Phenylalanine

“…Owing to the rapid development of genetic manipulation techniques and engineering of synthetic pathways, whole-cell biosynthesis has been used as an important strategy in the industrial production of several bulk and value-added fine chemicals. , It is commercially viable for whole-cell biosynthesis to be the approach for the production of compounds used in various fields, such as pharmacy, food, agriculture, beverages, and cosmetics . Developing continuous and sustainable whole-cell biosynthetic processes for the production of target chemicals has become increasingly attractive due to the need for large-scale and cost-effective production, as well as the present challenge of environmental issues.…”