A Synthetic Alternative to Canonical One-Carbon Metabolism

Area of Science:

• Metabolic Engineering
• Synthetic Biology
• Biochemistry

Background:

• One-carbon metabolism is essential, utilizing tetrahydrofolate-bound groups for biosynthesis.
• Canonical pathways rely on serine and glycine as one-carbon donors.
• Alternative pathways offer new metabolic capabilities.

Purpose of the Study:

• To design and establish an alternative cyclic one-carbon metabolism pathway.
• To utilize 4-hydroxy-2-oxobutanoic acid (HOB) as a novel one-carbon donor.
• To reprogram Escherichia coli metabolism and explore evolutionary divergence.

Main Methods:

• Designed a novel pathway substituting HOB for serine/glycine.
• Incorporated two new enzymatic reactions: l-homoserine transamination and HOB-hydroxymethyltransferase.
• Established the pathway in an Escherichia coli auxotroph via long-term cultivation and selection for prototrophy.

Main Results:

• Successfully established a functional HOB-dependent one-carbon pathway in E. coli.
• Demonstrated the recruitment of key enzymes and HOB as a crucial intermediate.
• Showcased biochemical reprogramming through minimal metabolic alteration and natural selection.

Conclusions:

• A novel, HOB-dependent one-carbon metabolic pathway was successfully engineered in E. coli.
• This reprogramming leverages natural selection, creating a unique evolutionary trajectory.
• The study highlights the potential for designing alternative metabolic systems.