title: Properties of engineered poly-3-hydroxyalkanoates produced in recombinant Escherichia coli strains.
abstract: To prepare medium-chain-length poly-3-hydroxyalkanoates (PHAs) with altered physical properties, we generated recombinant Escherichia coli strains that synthesized PHAs with altered monomer compositions. Experiments with different substrates (fatty acids with different chain lengths) or different E. coli hosts failed to produce PHAs with altered physical properties. Therefore, we engineered a new potential PHA synthetic pathway, in which ketoacyl-coenzyme A (CoA) intermediates derived from the beta-oxidation cycle are accumulated and led to the PHA polymerase precursor R-3-hydroxyalkanoates in E. coli hosts. By introducing the poly-3-hydroxybutyrate acetoacetyl-CoA reductase (PhbB) from Ralstonia eutropha and blocking the ketoacyl-CoA degradation step of the beta-oxidation, the ketoacyl-CoA intermediate was accumulated and reduced to the PHA precursor. Introduction of the phbB gene not only caused significant changes in the monomer composition but also caused changes of the physical properties of the PHA, such as increase of polymer size and loss of the melting point. The present study demonstrates that pathway engineering can be a useful approach for producing PHAs with engineered physical properties.
authors.affiliation: Institute of Biotechnology, Swiss Federal Institute of Technology, CH-8093 Zürich, Switzerland.
authors.forename: Q
authors.initials: Q
authors.lastname: Ren
authors.forename: N
authors.initials: N
authors.lastname: Sierro
authors.forename: M
authors.initials: M
authors.lastname: Kellerhals
authors.forename: B
authors.initials: B
authors.lastname: Kessler
authors.forename: B
authors.initials: B
authors.lastname: Witholt
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000235:genetics / Q000378:metabolism; D000102:Acetyl-CoA C-Acyltransferase / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D019748:Carbon-Carbon Double Bond Isomerases / Q000235:genetics / Q000378:metabolism; D004274:DNA, Recombinant; D064006:Dodecenoyl-CoA Isomerase; D004746:Enoyl-CoA Hydratase / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005818:Genetic Engineering; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D011091:Polyesters / Q000737:chemistry / Q000378:metabolism*; D019998:Racemases and Epimerases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004274:DNA, Recombinant; C057119:FadR protein, Bacteria; D009097:Multienzyme Complexes; D011091:Polyesters; D012097:Repressor Proteins; D015094:3-Hydroxyacyl CoA Dehydrogenases; D000102:Acetyl-CoA C-Acyltransferase; D004746:Enoyl-CoA Hydratase; D019998:Racemases and Epimerases; C029601:3-hydroxybutyryl-CoA epimerase; D019748:Carbon-Carbon Double Bond Isomerases; D064006:Dodecenoyl-CoA Isomerase