title: Metabolic engineering of a novel propionate-independent pathway for the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in recombinant Salmonella enterica serovar typhimurium.
abstract: A pathway was metabolically engineered to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a biodegradable thermoplastic with proven commercial applications, from a single, unrelated carbon source. An expression system was developed in which a prpC strain of Salmonella enterica serovar Typhimurium, with a mutation in the ability to metabolize propionyl coenzyme A (propionyl-CoA), served as the host for a plasmid harboring the Acinetobacter polyhydroxyalkanoate synthesis operon (phaBCA) and a second plasmid with the Escherichia coli sbm and ygfG genes under an independent promoter. The sbm and ygfG genes encode a novel (2R)-methylmalonyl-CoA mutase and a (2R)-methylmalonyl-CoA decarboxylase, respectively, which convert succinyl-CoA, derived from the tricarboxylic acid cycle, to propionyl-CoA, an essential precursor of 3-hydroxyvalerate (HV). The S. enterica system accumulated PHBV with significant HV incorporation when the organism was grown aerobically with glycerol as the sole carbon source. It was possible to vary the average HV fraction in the copolymer by adjusting the arabinose or cyanocobalamin (precursor of coenzyme B12) concentration in the medium.
authors.affiliation: Department of Chemical Engineering, University of California, Berkeley, California 94720-1462, USA.
authors.forename: Ilana S
authors.initials: IS
authors.lastname: Aldor
authors.forename: Seon-Won
authors.initials: SW
authors.lastname: Kim
authors.forename: Kristala L Jones
authors.initials: KL
authors.lastname: Prather
authors.forename: Jay D
authors.initials: JD
authors.lastname: Keasling
mesh_terms: D000214:Acyl Coenzyme A / Q000096:biosynthesis; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D002950:Citrate (si)-Synthase / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005818:Genetic Engineering / Q000379:methods*; D043586:Methylmalonyl-CoA Decarboxylase; D008765:Methylmalonyl-CoA Mutase / Q000235:genetics / Q000378:metabolism; D011091:Polyesters / Q000378:metabolism*; D011422:Propionates / Q000378:metabolism*; D011995:Recombination, Genetic; D012486:Salmonella typhimurium / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D014805:Vitamin B 12 / Q000378:metabolism; D000094122:Polyhydroxybutyrates
chemical_list: D000214:Acyl Coenzyme A; D002262:Carboxy-Lyases; D002950:Citrate (si)-Synthase; D043586:Methylmalonyl-CoA Decarboxylase; D008765:Methylmalonyl-CoA Mutase; D011091:Polyesters; D011422:Propionates; D014805:Vitamin B 12; C052620:poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate); D000094122:Polyhydroxybutyrates; C009061:propionyl-coenzyme A; C092884:methylcitrate synthase