A microbial factory for lactate-based polyesters using a lactate-polymerizing enzyme

Proc Natl Acad Sci U S A. 2008 Nov 11;105(45):17323-7. doi: 10.1073/pnas.0805653105. Epub 2008 Oct 31.

Abstract

Polylactate (PLA) is synthesized as a representative bio-based polyester by the chemo-bio process on the basis of metal catalyst-mediated chemical polymerization of lactate (LA) supplied by microbial fermentation. To establish the one-step microbial process for synthesis of LA-based polyesters, we explored whether polyhydroxyalkanoate (PHA) synthase would exhibit polymerizing activity toward a LA-coenzyme A (CoA), based on the fact that PHA monomeric constituents, especially 3-hydroxybutyrate (3HB), are structurally analogous to LA. An engineered PHA synthase was discovered as a candidate by a two-phase in vitro polymerization system previously developed. An LA-CoA producing Escherichia coli strain with a CoA transferase gene was constructed, and the generation of LA-CoA was demonstrated by capillary electrophoresis/MS analysis. Next, when the engineered PHA synthase gene was introduced into the resultant recombinant strain, we confirmed the one-step biosynthesis of the LA-incorporated copolyester, P(6 mol% LA-co-94 mol% 3HB), with a number-average molecular weight of 1.9 x 10(5), as revealed by gel permeation chromatography, gas chromatography/MS, and NMR.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / genetics
  • Acyltransferases / metabolism*
  • Chromatography, Gas
  • Coenzyme A / metabolism*
  • Electrophoresis, Capillary
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Lactic Acid / biosynthesis*
  • Mass Spectrometry
  • Nuclear Magnetic Resonance, Biomolecular
  • Polyesters
  • Polymers
  • Protein Engineering

Substances

  • Polyesters
  • Polymers
  • Lactic Acid
  • poly(lactide)
  • Acyltransferases
  • poly(3-hydroxyalkanoic acid) synthase
  • Coenzyme A