Metabolic and pathway engineering to influence native and altered erythromycin production through E. coli

The heterologous production of the complex antibiotic erythromycin through Escherichia coli provides a unique challenge in metabolic engineering. In addition to introducing the 19 foreign genes needed for heterologous biosynthesis, E coli metabolism must be engineered to provide the propionyl-CoA and (2S)-methylmalonyl-CoA substrates required to allow erythromycin formation. In this work, three different pathways to propionyl-CoA were compared in the context of supporting E coli erythromycin biosynthesis. The comparison revealed that alternative citramalate and threonine metabolic pathways (both starting from exogenous glycerol) were capable of supporting final compound formation equal to a proven pathway reliant upon exogenous propionate. Furthermore, two pathways to (2S)-methylmalonyl-CoA were compared in the production of a novel benzyl-erythromycin analog. A pathway dependent upon exogenous methylmalonate improved selectivity and facilitated antibiotic assessment of this new analog. (C) 2013 Elsevier Inc. All rights reserved.