Construction and application of an efficient methylation platform in Escherichia coli based on SAM regeneration

Methylation reactions are involved in the synthesis of various natural molecules, but the limited supply of intracellular S-adenosylmethionine (SAM) poses a challenge for the large-scale microbial production of methylated compounds. In this study, we conducted a comprehensive analysis and optimization of the SAM cycle regeneration pathway, enhancing the methylation efficiency in three key steps of the pathway (SAM carbon skeleton cycle, 5-methyltetrahydrofolate cycle, and adenine-ATP cycle), and constructed an efficient endogenous methylation platform in E. coli . This platform significantly increased the intracellular level of the cofactor SAM and improved methylation efficiency. Using this platform, the production of methylated products, including ferulic acid, vanillyl alcohol, and melatonin, increased by 4.2-fold, 1.28-fold, and 44.6 %, respectively. Notably, the ferulic acid titer reached 7.24 g/L, marking the highest level reported to date. These findings demonstrate the broad applicability of this methylation platform, providing a generalizable and effective approach for the biosynthesis of a wide range of SAM-dependent products.