Biosynthesis of glycolate-based polyesters containing medium-chain-length 3-hydroxyalkanoates in recombinant Escherichia coli expressing engineered polyhydroxyalkanoate synthase

Glycolate(GL)-based polyesters were for the first time produced in the recombinant Escherichia coli fatty acid β-oxidation pathway reinforcing mutant LS5218, using extracellularly added GL as a monomer precursor. Cells expressing a Ser325Thr/Gln481Lys mutant of polyhydroxyalkanoate synthase (PhaC1STQK) from Pseudomonas sp. 61-3, propionyl-CoA transferase from Megasphaera elsdenii and enoyl-CoA hydratase from Pseudomonas aeruginosa grown on GL and dodecanoate were found to produce novel copolymers of GL with 3-hydroxyalkanoates (3HAs) (C4–C12), P(GL-co-3HA), with a weight-average molecular weight of 34,000. The 1H and 13C NMR analyses of the copolymer revealed the incorporation of GL units into the polymer chain. This result demonstrates that PhaC1STQK polymerized glycolyl-CoA as a monomer substrate. Additionally, the novel lactate(LA)-based polyester P(LA-co-3HA) was produced by substituting GL with LA, indicating that the method is versatile and allows the production of a variety of biopolymers.

► Poly(glycolate-co-3-hydroxyalkanoates) was produced in E. coli expressing PhaC1STQK.
► Novel polyester P(lactate-co-3HA) was also synthesized using the same method.
► PhaC1STQK polymerizes 2-hydroxyalkanoate monomers with various carbon numbers.