RRC ID 52881
Author Vom Dorp K, Hölzl G, Plohmann C, Eisenhut M, Abraham M, Weber AP, Hanson AD, Dörmann P.
Title Remobilization of Phytol from Chlorophyll Degradation Is Essential for Tocopherol Synthesis and Growth of Arabidopsis.
Journal Plant Cell
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.
Volume 27(10)
Pages 2846-59
Published 2015-10
DOI 10.1105/tpc.15.00395
PII tpc.15.00395
PMID 26452599
PMC PMC4682318
MeSH Arabidopsis / genetics Arabidopsis / growth & development Arabidopsis / metabolism* Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism Biological Transport Biosynthetic Pathways Chlorophyll / metabolism Diphosphates / chemistry Diphosphates / metabolism Mutation Phosphorylation Phosphotransferases / genetics Phosphotransferases / metabolism Phylogeny Phytol / chemistry Phytol / metabolism* Plant Leaves / genetics Plant Leaves / growth & development Plant Leaves / metabolism Seeds / genetics Seeds / growth & development Seeds / metabolism Tocopherols / chemistry Tocopherols / metabolism*
IF 8.631
Arabidopsis / Cultured plant cells, genes pst00121 pst15134