(all-e)-phytoene and farnesyl-pyrophosphate

Longer-chain carotenoids have interesting physiological and electronic/photonic properties due to their extensive polyene structures. Establishing nonnatural biosynthetic pathways for longer-chain carotenoids in engineerable microorganisms will provide a platform to diversify and explore the potential of these molecules. We have previously reported the biosynthesis of nonnatural C

Topics: Bacterial Proteins; Biocompatible Materials; Biosynthetic Pathways; Carbon; Carotenoids; Escherichia coli; Geranylgeranyl-Diphosphate Geranylgeranyltransferase; Metabolic Engineering; Mutation; Oxidoreductases; Plasmids; Polyisoprenyl Phosphates; Sesquiterpenes

The role of carotenoid genes crtB and crtE has been functionally assigned. These genes were cloned from Erwinia into Escherichia coli or Agrobacterium tumefaciens. Their functions were elucidated by assaying early isoprenoid enzymes involved in phytoene formation. In vitro reactions from extracts of E. coli carrying the crtE gene or a complete carotenogenic gene cluster in which crtB was deleted showed an elevated conversion of farnesyl pyrophosphate (FPP) into geranylgeranyl pyrophosphate (GGPP). These results strongly indicate that the crtE gene encodes GGPP synthase. Introduction of the crtB gene into A. tumefaciens led to the conversion of GGPP into phytoene. This activity was absent in similar transformants with the crtE gene. Thus, the crtB gene probably encodes phytoene synthase, which was further supported by demonstration that phytoene accumulated in E. coli harboring both the crtB and crtE genes.

Topics: Agrobacterium tumefaciens; Alkyl and Aryl Transferases; Carotenoids; Chromatography, High Pressure Liquid; Dimethylallyltranstransferase; Erwinia; Escherichia coli; Genes, Bacterial; Geranylgeranyl-Diphosphate Geranylgeranyltransferase; Ligases; Plasmids; Polyisoprenyl Phosphates; Sesquiterpenes; Transformation, Bacterial