title: Synthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from unrelated carbon sources in engineered Rhodospirillum rubrum.
abstract: Different genes encoding pyridine nucleotide transhydrogenases (pntAB, udhA) and acetoacetyl-CoA reductases (phaB) were heterologously overexpressed in Rhodospirillum rubrum S1. A recombinant strain, which harbored the gene encoding the membrane-bound transhydrogenase PntAB from Escherichia coli MG1655 and the phaB1 gene coding for an NADPH-dependent acetoacetyl-CoA reductase from Ralstonia eutropha H16, accumulated poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [Poly(3HB-co-3HV)] with a 3HV fraction of up to 13 mol% from fructose. This was a 13-fold increase of the 3HV content when compared to the wild-type strain. Higher contents of 3HV are known to reduce the brittleness of this polymer, which is advantageous for most applications. The engineered R. rubrum strain was also able to synthesize this industrially relevant copolymer from CO2 and CO from artificial synthesis gas (syngas) with a 3HV content of 56 mol%. The increased incorporation of 3HV was attributed to an excess of propionyl-CoA, which was generated from threonine and related amino acids to compensate for the intracellular redox imbalance resulting from the transhydrogenase reaction. Thereby, our study presents a novel, molecular approach to alter the composition of bacterial PHAs independently from external precursor supply. Moreover, this study also provides a promising production strain for syngas-derived second-generation biopolymers.
authors.affiliation: Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany;
authors.forename: Daniel
authors.initials: D
authors.lastname: Heinrich
authors.affiliation: Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany;
authors.forename: Matthias
authors.initials: M
authors.lastname: Raberg
authors.affiliation: Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany; Environmental Sciences Department, King Abdulaziz University, Jeddah 21589, Saudi Arabia steinbu@uni-muenster.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Steinbüchel
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000429:Alcohol Oxidoreductases / Q000235:genetics; D002244:Carbon / Q000378:metabolism*; D020118:Cupriavidus necator / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D060847:Metabolic Engineering; D011091:Polyesters / Q000737:chemistry / Q000378:metabolism*; D054813:Polyhydroxyalkanoates / Q000032:analysis / Q000096:biosynthesis* / Q000737:chemistry; D011422:Propionates / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D012247:Rhodospirillum rubrum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D000094122:Polyhydroxybutyrates
chemical_list: D000214:Acyl Coenzyme A; D000429:Alcohol Oxidoreductases; D002244:Carbon; D011091:Polyesters; D054813:Polyhydroxyalkanoates; D011422:Propionates; D011994:Recombinant Proteins; C052620:poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate); D000094122:Polyhydroxybutyrates; C009061:propionyl-coenzyme A; C023744:acetoacetyl-CoA reductase
keywords: Rhodospirillum rubrum; poly(3HB-co-3HV); polyhydroxyalkanoates; syngas; transhydrogenases