title: Molecular cloning and expression in Escherichia coli of a cyanobacterial gene coding for phytoene synthase, a carotenoid biosynthesis enzyme.
abstract: The first committed step in the biosynthetic pathway of carotenoids in plants and algae is the conversion of geranylgeranyl pyrophosphate (GGPP) to prephytoene pyrophosphate (PPPP), which is converted to phytoene. We have cloned the gene pys that encodes the enzyme phytoene synthase in the cyanobacterium Synechococcus PCC7942. The co-expression of pys in cells of Escherichia coli together with the gene crtE from Erwinia uredovora, which encodes geranylgeranyl pyrophosphate synthase, resulted in accumulation of phytoene. This result indicates that phytoene synthase is a single polypeptide enzyme that catalyzes the 2-step reaction from GGPP to phytoene. The deduced amino acid sequence of pys is highly conserved with that of pTOM5, a tomato cDNA that is differentially expressed during fruit ripening. These findings suggest that pTOM5 encodes phytoene synthase in tomato.
authors.affiliation: Department of Genetics, Hebrew University of Jerusalem, Israel.
authors.forename: D
authors.initials: D
authors.lastname: Chamovitz
authors.forename: N
authors.initials: N
authors.lastname: Misawa
authors.forename: G
authors.initials: G
authors.lastname: Sandmann
authors.forename: J
authors.initials: J
authors.lastname: Hirschberg
mesh_terms: D019883:Alkyl and Aryl Transferases; D000595:Amino Acid Sequence; D001483:Base Sequence; D002338:Carotenoids / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000201:enzymology* / Q000235:genetics; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000235:genetics; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D008025:Ligases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010957:Plasmids; D011106:Polyisoprenyl Phosphates / Q000378:metabolism; D015183:Restriction Mapping; D016415:Sequence Alignment
chemical_list: D004269:DNA, Bacterial; D011106:Polyisoprenyl Phosphates; D002338:Carotenoids; C100185:(all-E) phytoene; D019883:Alkyl and Aryl Transferases; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D008025:Ligases; C002963:geranylgeranyl pyrophosphate