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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously, we have developed metabolically engineered Escherichia coli strains capable of producing polylactic acid (PLA) and poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] by employing evolved Clostridium propionicum propionate CoA transferase (Pct(Cp)) and Pseudomonas sp. MBEL 6-19 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1(Ps6-19)). Introduction of mutations four sites (E130, S325, S477, and Q481) of PhaC1( Ps6-19) have been found to affect the polymer content, lactate mole fraction, and molecular weight of P(3HB-co-LA). In this study, we have further engineered type II Pseudomonas PHA synthases 1 (PhaC1s) from Pseudomonas chlororaphis, Pseudomonas sp. 61-3, Pseudomonas putida KT2440, Pseudomonas resinovorans, and Pseudomonas aeruginosa PAO1 to accept short-chain-length hydroxyacyl-CoAs including lactyl-CoA and 3-hydroxybutyryl-CoA as substrates by site-directed mutagenesis of four sites (E130, S325, S477, and Q481). All PhaC1s having mutations in these four sites were able to accept lactyl-CoA as a substrate and supported the synthesis of P(3HB-co-LA) in recombinant E. coli, whereas the wild-type PhaC1s could not accumulate polymers in detectable levels. The contents, lactate mole fractions, and the molecular weights of P(3HB-co-LA) synthesized by recombinant E. coli varied depending upon the source of the PHA synthase and the mutants used. PLA homopolymer could also be produced at ca. 7 wt.% by employing the several PhaC1 variants containing E130D/S325T/S477G/Q481K quadruple mutations in wild-type E. coli XL1-Blue.
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PMID:Tailor-made type II Pseudomonas PHA synthases and their use for the biosynthesis of polylactic acid and its copolymer in recombinant Escherichia coli. 2122 71

We have previously reported in vivo biosynthesis of 2-hydroxyacid containing polyesters including polylactic acid (PLA), poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)], and poly(3-hydroxybutyrate-co-2-hydroxybutyrate-co-lactate) [P(3HB-co-2HB-co-LA)] employing metabolically engineered Escherichia coli strains by the introduction of evolved Clostridium propionicum propionyl-CoA transferase (Pct(Cp)) and Pseudomonas sp. MBEL 6-19 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1(Ps6-19)). In this study, we further engineered in vivo PLA biosynthesis system in E. coli to synthesize 2HB-containing PHA, in which propionyl-CoA was used as precursor for 2-ketobutyrate that was converted into 2HB-CoA by the sequential actions of Lactococcus lactis (D)-2-hydroxybutyrate dehydrogenase (PanE) and Pct(Cp) and then 2HB-CoA was polymerized by PhaC1(Ps6-19). The recombinant E. coli XL1-blue expressing the phaC1437 gene, the pct540 gene, and the Ralstonia eutropha prpE gene together with the panE gene could be grown to 0.66 g/L and successfully produced P(70 mol%3HB-co-18 mol%2HB-co-12 mol%LA) up to the PHA content of 66 wt% from 20 g/L of glucose, 2 g/L of 3HB and 1 g/L of sodium propionate. Removal of the prpC gene in the chromosome of E. coli XL1-blue could increase the mole fraction of 2HB in copolymer, but the PHA content was decreased. The metabolic engineering strategy reported here suggests that propionyl-CoA can be successfully used as the precursor to provide PHA synthase with 2HB-CoA for the production of PHAs containing 2HB monomer.
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PMID:Propionyl-CoA dependent biosynthesis of 2-hydroxybutyrate containing polyhydroxyalkanoates in metabolically engineered Escherichia coli. 2352 59