Production of Polyhydroxyalkanoate Copolymers in Transgenic Plants Expressing Engineered Enzymes

Abstract

Polyhydroxyalkanoates (PHAs) are bacterial polyesters that can be an alternative to petroleum-derived plastics. Transgenic plants harboring PHA biosynthetic genes are capable of producing PHAs directly from atmospheric CO₂. The properties of PHAs greatly depend on their monomer composition. Therefore, fine regulation of monomer composition is essential to the production of PHAs with the desired properties. In order to synthesize PHA copolymer in plants, the supply of monomers and the expression of PHA synthase (polymerizing enzyme) having a broad polymerizing capacity are required. We found that the engineered enzymes with enhanced activity and/or altered substrate specificity are functional in plant cells. This finding enabled us to produce PHA copolymer in transgenic plants.