Investigation of the Escherichia coli membrane transporters involved in the secretion of d-lactate-based oligomers by loss-of-function screening

Microbial Secretion Platform for 3‐Hydroxybutyrate Oligomer and Its End‐Capped Forms Using Chain Transfer Reaction‐Mediated Polyhydroxyalkanoate Synthases

“…In this study, we established a microbial secretion platform for 3HBOs via a PHA synthase‐operated system originating from glucose, a system inspired by the first detection of extracellularly secreted lactate‐based oligomers in the recombinant E. coli strain . In terms of enzymatic activity, the well‐studied PHA synthases PhaC Re and PhaEC Av have been shown to exhibit high CoA‐release activity toward 3HB‐CoA monomer substrates in vitro .…”

“…For industrialization, it is important to investigate the extracellular oligomer transportation system. In lactate‐based oligomers, seven types of membrane transporters (OmpG, OmpF, ArgT, MacA, MngA, CitA, CpxA) have been reported to be involved in secretory production . To investigate whether 3HBOs are secreted by means of transporters intended for lactate‐based oligomers, a loss‐of‐function assay was performed using seven E. coli BW25113 mutants.…”

“…In lactate‐based oligomers, seven types of membrane transporters (OmpG, OmpF, ArgT, MacA, MngA, CitA, CpxA) have been reported to be involved in secretory production . To investigate whether 3HBOs are secreted by means of transporters intended for lactate‐based oligomers, a loss‐of‐function assay was performed using seven E. coli BW25113 mutants. Quantitative analysis of intracellular and extracellular 3HBOs revealed that the seven membrane transporters are not involved in the secretion of 3HBOs.…”

“…In contrast, Utsunomia et al. first reported the secretory production of low‐molecular‐weight lactate‐based polymers (or oligomers) consisting of D‐lactate and ( R )‐3HB in a recombinant E. coli system using lactate‐polymerizing enzyme (LPE) . The secretion efficiency of lactate‐based oligomers was remarkably facilitated by an external addition of chain transfer (CT) agents such as diethylene glycol (DEG) .…”

“…The secretion efficiency of lactate‐based oligomers was remarkably facilitated by an external addition of chain transfer (CT) agents such as diethylene glycol (DEG) . In addition, transporter‐dependent secretion was observed for the outer and inner membranes of E. coli . Notably, the direct secretion of lactate‐based oligomers enabled us to establish a shortcut for producing poly(lactide) (PLA) via the ring‐opening polymerization of lactide converted from the lactate‐based oligomers .…”