Rewiring Escherichia coli to transform formate into methyl groups.

Area of Science:

• Synthetic biology
• Metabolic engineering
• Biotechnology

Background:

• Biotechnological applications are expanding, necessitating novel feedstocks beyond fossil resources.
• One-carbon (C1-) compounds like formate, derived from CO2 or waste, are abundant renewable resources.
• Previous work established formate assimilation in E. coli via C1-tetrahydrofolate (C1-H4F) metabolism.

Purpose of the Study:

• Investigate formate utilization for synthesizing value-added building blocks in E. coli.
• Employ S-adenosylmethionine (SAM)-dependent methyltransferases (MTs) for C1-compound conversion.
• Enhance microbial production of methylated compounds using engineered E. coli.

Main Methods:

• Engineered a two-vector system in E. coli BL21 to link formate assimilation and SAM-dependent methylation.
• Utilized isotopically labeled formate (13C) to trace metabolic pathways.
• Screened various formate concentrations to optimize conversion rates in engineered C1-auxotrophic E. coli C1S.

Main Results:

• Achieved 51-81% 13C-labeling in methylated products by feeding labeled formate.
• Demonstrated successful formate assimilation and subsequent methylation in E. coli.
• Doubled conversion rates in engineered E. coli C1S compared to the BL21 strain, with over 70% formate-derived methyl groups.

Conclusions:

• Successfully transformed formate into methyl groups within E. coli.
• Formate feeding enhances C1-compound availability and whole-cell methylation in engineered E. coli.
• Future work includes introducing auxiliary enzymes and improving system energy efficiency for broader applications.