Expression of 3-Ketoacyl-Acyl Carrier Protein Reductase (fabG) Genes Enhances Production of Polyhydroxyalkanoate Copolymer from Glucose in Recombinant Escherichia coli JM109

• Published in: Applied and Environmental Microbiology 2005-08, Vol.71 (8), p.4297-4306
• Main Authors: Nomura, Christopher T, Taguchi, Kazunori, Gan, Zhihua, Kuwabara, Kazuhiro, Tanaka, Tomoyo, Takase, Kazuma, Doi, Yoshiharu
• Format: Article
• Language: English
• Subjects: 3-Oxoacyl-(Acyl-Carrier-Protein) Reductase; Acyltransferases - genetics; Acyltransferases - metabolism; Alcohol Oxidoreductases - genetics; Alcohol Oxidoreductases - metabolism; Bacteria; Bacterial proteins; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological and medical sciences; Biotechnology; Culture Media; Enzymes; Escherichia coli; Escherichia coli - genetics; Escherichia coli - growth & development; Escherichia coli - metabolism; Fatty Acids - biosynthesis; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Bacterial; Genes; Genetic engineering; Genetic recombination; Genetic technics; Glucose; Glucose - metabolism; Methods. Procedures. Technologies; Modification of gene expression level; Physiology and Biotechnology; Polyesters - metabolism; Polymers; Pseudomonas; Pseudomonas - enzymology; Pseudomonas - genetics; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Substrate Specificity
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.71.8.4297-4306.2005

Polyhydroxyalkanoates (PHAs) are biologically produced polyesters that have potential application as biodegradable plastics. Especially important are the short-chain-length-medium-chain-length (SCL-MCL) PHA copolymers, which have properties ranging from thermoplastic to elastomeric, depending on the ratio of SCL to MCL monomers incorporated into the copolymer. Because of the potential wide range of applications for SCL-MCL PHA copolymers, it is important to develop and characterize metabolic pathways for SCL-MCL PHA production. In previous studies, coexpression of PHA synthase genes and the 3-ketoacyl-acyl carrier protein reductase gene (fabG) in recombinant Escherichia coli has been shown to enhance PHA production from related carbon sources such as fatty acids. In this study, a new fabG gene from Pseudomonas sp. 61-3 was cloned and its gene product characterized. Results indicate that the Pseudomonas sp. 61-3 and E. coli FabG proteins have different substrate specificities in vitro. The current study also presents the first evidence that coexpression of fabG genes from either E. coli or Pseudomonas sp. 61-3 with fabH(F87T) and PHA synthase genes can enhance the production of SCL-MCL PHA copolymers from nonrelated carbon sources. Differences in the substrate specificities of the FabG proteins were reflected in the monomer composition of the polymers produced by recombinant E. coli. SCL-MCL PHA copolymer isolated from a recombinant E. coli strain had improved physical properties compared to the SCL homopolymer poly-3-hydroxybutyrate. This study defines a pathway to produce SCL-MCL PHA copolymer from the fatty acid biosynthesis that may impact on PHA production in recombinant organisms.