Role of tomato hexose kinases
Role of tomato hexose kinases
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DOI：
10.1071/fp06207
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发表时间：
2007-01-01
影响因子：
3
通讯作者：
Granot, David
中科院分区：
文献类型：
--
作者：
Granot, David
己糖磷酸化是糖代谢的重要步骤。在植物中发现的葡萄糖和果糖磷酸化酶只有两类：己糖激动酶(HXK)和果糖激动酶(FRK)。番茄(Lycpers sice esculentum Mill.)是唯一一种已鉴定出四个HXK和四个FrK基因的植物物种。一种HXK同工酶和一种FRK同工酶位于叶绿体内。另外三种HXK同工酶与线粒体结合，另外三种FRK同工酶分布在胞浆中。这些位置上的差异表明，细胞质HXK和FRK在糖代谢中起着不同的作用。利用转基因植物研究了HXK和Frk基因的具体作用。通过修改线粒体相关HXK的表达，获得了糖信号转导效应。相反，胞质Frk的修饰表达影响了果糖代谢，而不是糖信号。未来的研究工作将致力于确定特定的己糖磷酸化酶在番茄植株中的作用，将被磷酸化的己糖单体的来源，以及它们在细胞内的运输途径。
Hexose phosphorylation is an essential step of sugar metabolism. Only two classes of glucose and fructose phosphorylating enzymes, hexokinases (HXK) and fructokinases (FRK), have been found in plants. Tomato (Lycopersicon esculentum Mill.) is the only plant species from which four HXK and four FRK genes have been identified and characterised. One HXK and one FRK isozyme are located within plastids. The other three HXK isozymes are associated with the mitochondria, and the other three FRK isozymes are dispersed in the cytosol. These differences in location suggest that the cytoplasmic HXK and FRK have distinct roles to play in sugar metabolism. The specific roles of each of the HXK and FRK genes have been investigated using transgenic plants with modified expression of the genes. Sugar signalling effects were obtained with modified expression of the mitochondria associated HXK. In contrast, modified expression of the cytosolic FRK affected fructose metabolism rather than sugar signalling. Future research efforts will aim to determining the roles of specific hexose phosphorylating enzymes in tomato plants, the source of the hexose monomers to be phosphorylated, and their intracellular trafficking route.