title: Characterisation of plant tocopherol cyclases and their overexpression in transgenic Brassica napus seeds.
abstract: Tocopherols, collectively known as vitamin E, are only synthesised in photosynthetic organisms. Tocopherol cyclase (TC) catalyses the formation of the chromanol headgroup of the various tocopherol isoforms. TCs from Arabidopsis and maize (Zea mays) were expressed in Escherichia coli and purified. Analysis of the enzymatic properties revealed similarities but also differences between the two enzymes. Overexpression of chimeric TC gene constructs in developing seeds of transgenic rapeseed plants enhanced and modified the relative abundance of individual tocochromanol species in the seed oil, indicating a regulatory function of the enzyme in prenyllipid metabolism.
authors.affiliation: RWTH Aachen University, Institute for Biology I-Botany, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Kumar
authors.forename: Mirela
authors.initials: M
authors.lastname: Raclaru
authors.forename: Thomas
authors.initials: T
authors.lastname: Schüsseler
authors.forename: Jens
authors.initials: J
authors.lastname: Gruber
authors.forename: Radin
authors.initials: R
authors.lastname: Sadre
authors.forename: Wilfried
authors.initials: W
authors.lastname: Lühs
authors.forename: Karim M
authors.initials: KM
authors.lastname: Zarhloul
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Friedt
authors.forename: Dieter
authors.initials: D
authors.lastname: Enders
authors.forename: Margrit
authors.initials: M
authors.lastname: Frentzen
authors.forename: Dagmar
authors.initials: D
authors.lastname: Weier
mesh_terms: D017360:Arabidopsis / Q000201:enzymology; D029688:Brassica napus / Q000201:enzymology* / Q000235:genetics; D015870:Gene Expression; D017343:Genes, Plant / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D019751:Intramolecular Transferases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015394:Molecular Structure; D030821:Plants, Genetically Modified; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012639:Seeds / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity; D013696:Temperature; D024505:Tocopherols / Q000737:chemistry / Q000378:metabolism; D003313:Zea mays / Q000201:enzymology
chemical_list: D011994:Recombinant Proteins; D019751:Intramolecular Transferases; C103397:tocopherol cyclase; D024505:Tocopherols