Biosynthesis of medium-chain-length poly(hydroxyalkanoates) with altered composition by mutant hybrid PHA synthases

Original Paper

Abstract

Pseudomonas resinovorans harbors two isogenic poly(hydroxyalkanoates) (PHAs) synthase genes (phaC1Pre, phaC2Pre) responsible for the production of intracellular medium-chain-length (mcl-)PHAs. Sequence analysis showed that the putative gene-products of these genes contain a conserved α/β-hydrolase fold in the carboxy-terminal half of the proteins. Hybrid genes pha7 and pha8 were constructed by exchanging the α/β-hydrolase-fold coding portions of phaC1Pre and phaC2Pre at the 3′ terminal. When grown with decanoate as carbon source, the pha7- or pha8-transformed Escherichia coli LS1298 produced PHAs containing 73–75% β-hydroxydecanoate (β-HD) and 25–27% β-hydroxyoctanoate (β-HO). Deletion mutants, Δpha7 and Δpha8, were isolated during the PCR-based construction of pha7 and pha8, respectively. Cells harboring these mutants produced PHAs containing 55–60 mol% β-HD and 40–45 mol% β-HO. These results demonstrate the feasibility of generating active hybrid mcl-PHA synthase genes and their mutants with the potential of producing polymers having a varied repeat-unit composition.

Keywords

α/β-Hydrolase fold Hybrid gene Poly(hydroxyalkanoate) synthases 

Copyright information

© Society for Industrial Microbiology 2003

Authors and Affiliations

  1. 1.Eastern Regional Research Center, Agricultural Research ServiceUnited States Department of AgricultureWyndmoorUSA

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