Improved methylation in E. coli via an efficient methyl supply system driven by betaine

Area of Science:

• Metabolic Engineering
• Synthetic Biology
• Biochemistry

Background:

• S-adenosyl-L-methionine (SAM) is the primary biological methyl donor for natural molecule biosynthesis.
• Limited SAM availability restricts methylated metabolite production, particularly with heterologous methyltransferases.

Purpose of the Study:

• To engineer a robust methyl supply system using betaine to enhance intracellular SAM levels.
• To improve the production of methylated natural products via increased SAM availability.

Main Methods:

• Reconstruction of a methionine cycle in E. coli utilizing betaine as the methyl source.
• Introduction of betaine-homocysteine methyltransferase and an ATP regeneration pathway.
• Optimization of S-adenosyl-L-homocysteine (SAH) hydrolysis via the SAHase pathway.

Main Results:

• The developed system significantly increased SAM availability in engineered E. coli.
• Ferulic acid production, a model methylated product, saw a 12.6-fold increase in titer and 15.9-fold increase in productivity.
• The methyl supply system demonstrated efficacy in other methyltransferase-catalyzed reactions.

Conclusions:

• A novel and efficient betaine-driven methyl supply system was successfully established.
• This system enhances SAM availability, leading to improved yields of methylated chemicals.
• The strategy provides a valuable tool for the biotechnological production of diverse methylated compounds.