title: A tomato gene expressed during fruit ripening encodes an enzyme of the carotenoid biosynthesis pathway.
abstract: In the initial stages of carotenoid biosynthesis in plants the enzyme phytoene synthase converts two molecules of geranylgeranyl diphosphate into phytoene, the first carotenoid of the pathway. We show here that a tomato (Lycopersicon esculentum) cDNA for a gene (Psy1) expressed during fruit ripening directs the in vitro synthesis of a 47-kDa protein which, upon import into isolated chloroplasts, is processed to a mature 42-kDa form. The imported protein is largely associated with membranes, but it can be easily solubilized by dilution or by treatment at high pH. A plasmid construct containing prokaryotic promoter and ribosome-binding sequences fused to the Psy1 cDNA complements the carotenoidless phenotype of a Rhodobacter capsulatus crtB mutant. We conclude that Psy1 encodes phytoene synthase and that this enzyme is a peripheral plastid membrane protein.
authors.affiliation: Central Research and Development, Du Pont de Nemours & Company, Wilmington, Delaware 19880-0402.
authors.forename: G E
authors.initials: GE
authors.lastname: Bartley
authors.forename: P V
authors.initials: PV
authors.lastname: Viitanen
authors.forename: K O
authors.initials: KO
authors.lastname: Bacot
authors.forename: P A
authors.initials: PA
authors.lastname: Scolnik
mesh_terms: D019883:Alkyl and Aryl Transferases; D000595:Amino Acid Sequence; D001483:Base Sequence; D002736:Chloroplasts / Q000201:enzymology; D003001:Cloning, Molecular; D005638:Fruit; D015971:Gene Expression Regulation, Enzymologic; D017343:Genes, Plant; D005816:Genetic Complementation Test; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D008025:Ligases / Q000235:genetics*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D018521:Plant Physiological Phenomena; D010944:Plants / Q000201:enzymology / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D009838:Oligodeoxyribonucleotides; D019883:Alkyl and Aryl Transferases; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D008025:Ligases