19. シロイヌナズナのHMG-CoAレダクターゼ阻害剤に対する耐性変異体loi1の解析

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Higher plants have two metabolic pathways for isoprenoid biosynthesis : the cytosolic mevalonate (MVA) pathway and the plastidic non-mevalonate (MEP) pathway. It has been reported that metabolic flow exists between these pathways. Lovastatin is a specific inhibitor of HMG-CoA reductase, which is a key enzyme of the MVA pathway. To study the regulatory mechanism of the MVA pathway in plants, we have isolated a lovastatin resistant mutant from T-DNA tagged lines of Arabidopsis, designated as lovastatin insensitive 1 (loi1). loi1 was resistant to lovastatin but sensitive to squalestatin, an inhibitor of squalene synthase. These results suggested that loi1 mutation may up-regulate the upstream of the MVA pathway. To investigate this possibility, contents of sterol (the MVA pathway products) of lovastatin-treated loi1 and wild type were compared. The total sterols of loi1 treated with low concentration of lovastatin was not reduced compared to those of wild type. To examine whether MEP pathway contribute to the lovastatin resistant phenotype, the sensitivity to clomazone of loi1 was examined. loi1 was resistant to clomazone, suggesting that loi1 mutation affected the MEP pathway as well as the MVA pathway. In loi1 mutant, T-DNA was tagged in a gene encoding a putative protein which has pentatricopeptide repeat (PPR) motif. The allelic mutants showed the phenotypes similar to loi1. Therefore, we have designated this gene LOI1. The PPR proteins constitute large family in plants. Most of PPR proteins are predicted to take part in the regulation of organellar gene expression. To investigate whether LOI1 can bind to nucleic acids, south- and north-western analyses using GST-LOI1 were performed. It was confirmed that LOI1 has an ability to bind single strand nucleic acids.
2004-10-13

19. シロイヌナズナのHMG-CoAレダクターゼ阻害剤に対する耐性変異体loi1の解析

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