PDF(Pubmed)
Abstract：
Isoprenoids are a wide family of metabolites including high-value chemicals, flavors, pigments, and drugs. Isoprenoids are particularly abundant and diverse in plants. The methyl-D-erythritol 4-phosphate (MEP) pathway produces the universal isoprenoid precursors isopentenyl diphosphate and dimethylallyl diphosphate in plant plastids for the downstream production of monoterpenes, diterpenes, and photosynthesis-related isoprenoids such as carotenoids, chlorophylls, tocopherols, phylloquinone, and plastoquinone. The enzyme deoxy-D-xylulose 5-phosphate synthase (DXS) is the first and main rate-determining enzyme of the MEP pathway. In tomato (Solanum lycopersicum), a plant with an active isoprenoid metabolism in several tissues, three genes encode DXS-like proteins (SlDXS1 to 3). Here, we show that the expression patterns of the three genes suggest distinct physiological roles without excluding that they might function together in some tissues. We also confirm that SlDXS1 and 2 are true DXS enzymes, whereas SlDXS3 lacks DXS activity. We further show that SlDXS1 and 2 co-localize in plastidial speckles and that they can be immunoprecipitated together, suggesting that they might form heterodimers in vivo in at least some tissues. These results provide novel insights for the biotechnological use of DXS isoforms in metabolic engineering strategies to up-regulate the MEP pathway flux.
摘要：
类异戊二烯是一个广泛的代谢产物家族，包括高价值的化学物质，口味,颜料,和毒品。类异戊二烯在植物中特别丰富和多样。甲基-D-赤藓糖醇4-磷酸（MEP）途径在植物质体中产生通用的类异戊二烯前体异戊烯基二磷酸和二甲基烯丙基二磷酸，用于下游生产单萜，二萜,和光合作用相关的类异戊二烯，如类胡萝卜素，叶绿素，生育酚,苯醌,和质体醌.酶脱氧-D-木酮糖5-磷酸合酶（DXS）是MEP途径的第一个也是主要的速率决定酶。在番茄（Solanumlycopersicum）中，在几种组织中具有活跃的类异戊二烯代谢的植物，三个基因编码DXS样蛋白(SlDXS1至3)。这里,我们表明，这三个基因的表达模式表明了不同的生理作用，但不排除它们可能在某些组织中共同发挥作用。我们还确认SlDXS1和2是真正的DXS酶，而SlDXS3缺乏DXS活性。我们进一步表明，SlDXS1和2共定位在质体斑点中，并且它们可以一起免疫沉淀，这表明它们可能在体内至少在一些组织中形成异二聚体。这些结果为DXS同工型在代谢工程策略中的生物技术用途提供了新的见解，以上调MEP途径通量。
