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

Original Paper


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.


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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