title: The role of 2-methyl-6-phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803.
abstract: A putative 2-methyl-6-phytylbenzoquinone (MPBQ) methyltransferase gene, SLL0418, was identified from the Synechocystis PCC6803 genome based on its homology to previously characterized gamma-tocopherol methyltransferases. Genetic and biochemical evidence confirmed open reading frame (ORF) SLL0418 encodes a MPBQ methyltransferase. An SLL0418 partial knockout mutant accumulated beta-tocopherol with no effect in the overall tocopherol content of the cell. In vitro assays of the SLL0418 gene expressed in Escherichia coli showed the enzyme efficiently catalyzes methylation of ring carbon 3 of MPBQ. In addition, the enzyme also catalyzes the methylation of ring carbon 3 of 2-methyl-6-solanylbenzoquinol in the terminal step of plastoquinone biosynthesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Shintani
authors.forename: Zigang
authors.initials: Z
authors.lastname: Cheng
authors.forename: Dean
authors.initials: D
authors.lastname: DellaPenna
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D008401:Gas Chromatography-Mass Spectrometry; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010971:Plastoquinone / Q000031:analogs & derivatives* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D024505:Tocopherols / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*
chemical_list: C000868:demethylphytylplastoquinone; C447422:2-methyl-6-phytylbenzoquinone methyltransferase; D008780:Methyltransferases; D010971:Plastoquinone; D024505:Tocopherols