title: Remobilization of Phytol from Chlorophyll Degradation Is Essential for Tocopherol Synthesis and Growth of Arabidopsis.
abstract: Phytol from chlorophyll degradation can be phosphorylated to phytyl-phosphate and phytyl-diphosphate, the substrate for tocopherol (vitamin E) synthesis. A candidate for the phytyl-phosphate kinase from Arabidopsis thaliana (At1g78620) was identified via a phylogeny-based approach. This gene was designated VITAMIN E DEFICIENT6 (VTE6) because the leaves of the Arabidopsis vte6 mutants are tocopherol deficient. The vte6 mutant plants are incapable of photoautotrophic growth. Phytol and phytyl-phosphate accumulate, and the phytyl-diphosphate content is strongly decreased in vte6 leaves. Phytol feeding and enzyme assays with Arabidopsis and recombinant Escherichia coli cells demonstrated that VTE6 has phytyl-P kinase activity. Overexpression of VTE6 resulted in increased phytyl-diphosphate and tocopherol contents in seeds, indicating that VTE6 encodes phytyl-phosphate kinase. The severe growth retardation of vte6 mutants was partially rescued by introducing the phytol kinase mutation vte5. Double mutant plants (vte5 vte6) are tocopherol deficient and contain more chlorophyll, but reduced amounts of phytol and phytyl-phosphate compared with vte6 mutants, suggesting that phytol or phytyl-phosphate are detrimental to plant growth. Therefore, VTE6 represents the missing phytyl-phosphate kinase, linking phytol release from chlorophyll with tocopherol synthesis. Moreover, tocopherol synthesis in leaves depends on phytol derived from chlorophyll, not on de novo synthesis of phytyl-diphosphate from geranylgeranyl-diphosphate.
authors.affiliation: Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, 53115 Bonn, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Vom Dorp
authors.affiliation: Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, 53115 Bonn, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Hölzl
authors.affiliation: Institute of Plant Biochemistry, Cluster of Excellence on Plant Science (CEPLAS) Heinrich-Heine-University, 40225 Düsseldorf, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Plohmann
authors.affiliation: Institute of Plant Biochemistry, Cluster of Excellence on Plant Science (CEPLAS) Heinrich-Heine-University, 40225 Düsseldorf, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Eisenhut
authors.affiliation: Leibniz Institute for Baltic Sea Research, 18119 Rostock, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Abraham
authors.affiliation: Institute of Plant Biochemistry, Cluster of Excellence on Plant Science (CEPLAS) Heinrich-Heine-University, 40225 Düsseldorf, Germany.
authors.forename: Andreas P M
authors.identifier: http://orcid.org/0000-0003-0970-4672
authors.initials: AP
authors.lastname: Weber
authors.affiliation: Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611.
authors.forename: Andrew D
authors.identifier: http://orcid.org/0000-0003-2585-9340
authors.initials: AD
authors.lastname: Hanson
authors.affiliation: Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, 53115 Bonn, Germany doermann@uni-bonn.de.
authors.forename: Peter
authors.identifier: http://orcid.org/0000-0002-5845-9370
authors.initials: P
authors.lastname: Dörmann
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D053898:Biosynthetic Pathways; D002734:Chlorophyll / Q000378:metabolism; D011756:Diphosphates / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010836:Phytol / Q000737:chemistry / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D024505:Tocopherols / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D011756:Diphosphates; C529546:phytyl diphosphate; D002734:Chlorophyll; D010836:Phytol; D010770:Phosphotransferases; D024505:Tocopherols