Role of Fatty Acid De Novo Biosynthesis in Polyhydroxyalkanoic Acid (PHA) and Rhamnolipid Synthesis by Pseudomonads: Establishment of the Transacylase (PhaG)-Mediated Pathway for PHA Biosynthesis in Escherichia coli
Open Access
- 1 July 2001
- journal article
- Published by American Society for Microbiology in Applied and Environmental Microbiology
- Vol. 67 (7) , 3102-3109
Abstract
Since Pseudomonas aeruginosa is capable of biosynthesis of polyhydroxyalkanoic acid (PHA) and rhamnolipids, which contain lipid moieties that are derived from fatty acid biosynthesis, we investigated various fab mutants from P. aeruginosa with respect to biosynthesis of PHAs and rhamnolipids. All isogenic fabA, fabB, fabI, rhlG , and phaG mutants from P. aeruginosa showed decreased PHA accumulation and rhamnolipid production. In the phaG (encoding transacylase) mutant rhamnolipid production was only slightly decreased. Expression of phaG from Pseudomonas putida and expression of the β-ketoacyl reductase gene rhlG from P. aeruginosa in these mutants indicated that PhaG catalyzes diversion of intermediates of fatty acid de novo biosynthesis towards PHA biosynthesis, whereas RhlG catalyzes diversion towards rhamnolipid biosynthesis. These data suggested that both biosynthesis pathways are competitive. In order to investigate whether PhaG is the only linking enzyme between fatty acid de novo biosynthesis and PHA biosynthesis, we generated five Tn 5 mutants of P. putida strongly impaired in PHA production from gluconate. All mutants were complemented by the phaG gene from P. putida , indicating that the transacylase-mediated PHA biosynthesis route represents the only metabolic link between fatty acid de novo biosynthesis and PHA biosynthesis in this bacterium. The transacylase-mediated PHA biosynthesis route from gluconate was established in recombinant E. coli , coexpressing the class II PHA synthase gene phaC1 together with the phaG gene from P. putida , only when fatty acid de novo biosynthesis was partially inhibited by triclosan. The accumulated PHA contributed to 2 to 3% of cellular dry weight.Keywords
This publication has 43 references indexed in Scilit:
- ThePseudomonas aeruginosa phaGgene product is involved in the synthesis of polyhydroxyalkanoic acid consisting of medium-chain-length constituents from non-related carbon sourcesFEMS Microbiology Letters, 2000
- Metabolic routing towards polyhydroxyalkanoic acid synthesis in recombinantEscherichia coli(fadR): inhibition of fatty acid β-oxidation by acrylic acidFEMS Microbiology Letters, 1998
- A New Metabolic Link between Fatty Acid de NovoSynthesis and Polyhydroxyalkanoic Acid SynthesisJournal of Biological Chemistry, 1998
- Synthesis of poly(3-hydroxyalkanoates) in Escherichia coli expressing the PHA synthase gene phaC2 from Pseudomonas aeruginosa: comparison of PhaC1 and PhaC2FEMS Microbiology Letters, 1997
- Functional expression of the PHA synthase gene C1 from in results in poly(3-hydroxyalkanoate) synthesisFEMS Microbiology Letters, 1997
- Four new derivatives of the broad-host-range cloning vector pBBR1MCS, carrying different antibiotic-resistance cassettesGene, 1995
- Diversity of bacterial polyhydroxyalkanoic acidsFEMS Microbiology Letters, 1995
- .beta.-Hydroxydecanoyl thioester dehydrase does not catalyze a rate-limiting step in Escherichia coli unsaturated fatty acid synthesisBiochemistry, 1983
- A Broad Host Range Mobilization System for In Vivo Genetic Engineering: Transposon Mutagenesis in Gram Negative BacteriaBio/Technology, 1983
- Inhibition of fatty acid synthesis by the antibiotic ceruleninBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1973