A modified serine cycle in Escherichia coli coverts methanol and CO2 to two-carbon compounds

Microbial utilization of renewable one-carbon compounds, such as methane, methanol, formic acid, and CO2, has emerged as a potential approach to increase the range of carbon sources for bioproduction and address climate change issues. Here, we modify the natural serine cycle present in methylotrophs and build an adapted pathway for Escherichia coli, which allows microorganism to condense methanol (or formate) together with bicarbonate to produce various products. We introduce the modified cycle into E. coli and demonstrate its capability for one-carbon assimilation through growth complementation and isotope labeling experiments. We also demonstrate conversion of methanol to ethanol by utilizing the modified serine cycle in an engineered E. coli strain, achieving a reaction yet to be accomplished by a one-pot chemical process. This work provides a platform to utilize various renewable one-carbon compounds as carbon sources for biosynthesis through a modified serine cycle in E. coli.Assimilating the abundant one-carbon compounds by an industrially-relevant microorganism can broaden the substrate range and achieve reactions that are difficult for chemical process. Here the authors show a modified serine cycle can convert methanol and CO2 to two-carbon compounds in an engineered E. coli strain.