植物の糖・脂質代謝制御に関わるプロテインキナーゼに関する研究

概要

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Plants need to be able to respond to the availability of metabolites, such as sugar and lipid. In many cases, the metabolic responses are mediated by alterations in the expression of genes and/or the dification of proteins. cDNA (cNPK5) that encodes a protein kinase was isolated from tabacco cells. NPK5 was found to be a functional homologue of yeast SNF1 protein kinase, which plays a central role in catabolite ression in yeast cells. From the experiments of yeast twohybrid system, several proteins such as Arabidopsis PRL1 and tomato SNF4 homologue that interact with NPK5 was identified.On the other hand, mammalian AMP-activated protein kinase (AMPK), which shows high degree of structural conservation to SNF1, was shown to phosphorylate and inactivate HMG-CoA reductase (HMGR), the regulatory enzyme of isoprenoid biosynthesis. The recombinant NPK5 protein in E. coli phosphorylated and inactivated HMGR protein. The phosphrylation site was identified by using tandem mass spectrometry analysis. Structural homologue of NPK5 are found in many higher plants, such as Arabidopsis, potato, race and rye. These results indicate that NPK5 and that of plant homologue are multifunctional regulator of both sugar and lipid metabolism in plants.
植物化学調節学会の論文
1999-10-01