Peroxisomes as sites for synthesis of polyhydroxyalkanoates in transgenic plants

Bacterial genes responsible for poly(3-hydroxybutyrate) (PHB) biosynthesis were targeted to plant peroxisomes by adding a carboxy-terminal targeting s equence. The enzymes evidently were transported into peroxisomes, retained their catalytic activity, and reacted with peroxisomally available precurso rs because PHB synthesis in transgenic plant cells was localized to peroxis omes. Up to 2 mg/g fresh weight PHB was produced in suspension cultures of Black Mexican Sweet maize cells after biolistic transformation with three p eroxisomally targeted bacterial genes. An equilibrium effect is proposed to explain the unexpected existence of (R)-3-hydroxybutyryl-CoA in plant pero xisomes.