title: Engineering of ubiquinone biosynthesis using the yeast coq2 gene confers oxidative stress tolerance in transgenic tobacco.
abstract: Ubiquinone (UQ), an electron carrier in the respiratory chain ranging from bacteria to humans, shows antioxidative activity in vitro, but its physiological role in vivo is not yet clarified in plants. UQ biosynthesis was modified by overexpressing the yeast gene coq2, which encodes p-hydroxybenzoate:polyprenyltransferase, to increase the accumulation of UQ-6 in yeast and UQ-10 in tobacco. The yeast and tobacco transgenic lines showed about a three- and six-fold increase in UQ, respectively. COQ2 polypeptide, the localization of which was forcibly altered to the endoplasmic reticulum, had the same or a greater effect as mitochondria-localized COQ2 on the increase in UQ in both the yeast and tobacco transformants, indicating that the UQ intermediate is transported from the endoplasmic reticulum to the mitochondria. Plants with a high UQ level are more resistant to oxidative stresses caused by methyl viologen or high salinity. This is attributable to the greater radical scavenging ability of the transgenic lines when compared with the wild type.
authors.affiliation: Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Uji 611-0011, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Ohara
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Kokado
authors.forename: Hirobumi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Yazaki
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics* / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000201:enzymology; D018506:Gene Expression Regulation, Plant; D005818:Genetic Engineering; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010641:Phenotype; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism; D014451:Ubiquinone / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D017382:Reactive Oxygen Species; D014451:Ubiquinone; D019883:Alkyl and Aryl Transferases; C025204:Ubiquinone Q2