An Unnatural Pathway for Efficient 5-Aminolevulinic Acid Biosynthesis with Glycine from Glyoxylate Based on Retrobiosynthetic Design.

The design of novel metabolic pathways for efficient biosynthesis of natural products has received much interest, but often lacks systematic approach and chemistry-based guideline. Here we propose carbon skeleton reconstruction based on retrobiosynthetic design as a new approach and chemistry-guideline to solve the problem of properly matching precursors, one of the key issues for efficient biosynthesis. It is demonstrated for the development of an unnatural pathway for efficient biosynthesis of 5-aminolevulinic acid. The new pathway has several advantages compared to the existing natural ones such as high carbon utilization efficiency and orthogonality. It is particularly useful for overcoming the problem of glycine supply. The unnatural pathway is verified in vitro in an enzymatic cascade and in vivo in recombinant E. coli with an exogenous glyoxylate transaminase as a key enzyme.