The yeast GID complex, a novel ubiquitin ligase (E3) involved in the regulation of carbohydrate metabolism
The yeast GID complex, a novel ubiquitin ligase (E3) involved in the regulation of carbohydrate metabolism
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DOI：
10.1091/mbc.e08-03-0328
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发表时间：
2008-08-01
影响因子：
3.3
通讯作者：
Wolf, Dieter H.
中科院分区：
文献类型：
--
作者：
Santt, Olivier;Pfirrmann, Thorsten;Wolf, Dieter H.
葡萄糖依赖性的碳代谢调节是一个深入研究的课题。我们先前已经表明，从糖酵解到异生的转换与泛素-蛋白酶体相关的关键酶果糖-1，6-二磷酸酶的消除有关。先前在基因组筛选中发现的七种葡萄糖诱导的降解缺陷（Gid）蛋白显示形成结合FBPase的复合物。其中一个亚基Gid 2/Rmd 5含有简并的RING指结构域。在体外测定中，GST-Gid 2的异源表达导致蛋白质的多泛素化。此外，我们表明，在Gid 2/Rmd 5的退化环域的突变废除果糖-1，6-二磷酸酶多泛素化和消除体内。六个Gid蛋白存在于致瘤细胞中。第七种蛋白质，Gid 4/Vid 24，在葡萄糖添加到致炎细胞后发生，然后被消除。Gid 4/Vid 24的异常表达导致果糖-1，6-二磷酸酶降解。这表明Gid 4/Vid 24通过Gid复合物启动果糖-1，6-二磷酸酶聚泛素化，并随后通过蛋白酶体消除。我们还表明，一个额外的促凋亡酶，磷酸烯醇式丙酮酸羧激酶，是受Gid复合物依赖性降解。我们的研究揭示了一种新型的泛素连接酶复合物，由参与碳水化合物代谢的新亚基组成，并确定Gid 4/Vid 24为E3的主要调节因子。
Glucose-dependent regulation of carbon metabolism is a subject of intensive studies. We have previously shown that the switch from gluconeogenesis to glycolysis is associated with ubiquitin-proteasome linked elimination of the key enzyme fructose-1,6-bisphosphatase. Seven glucose induced degradation deficient (Gid)-proteins found previously in a genomic screen were shown to form a complex that binds FBPase. One of the subunits, Gid2/Rmd5, contains a degenerated RING finger domain. In an in vitro assay, heterologous expression of GST-Gid2 leads to polyubiquitination of proteins. In addition, we show that a mutation in the degenerated RING domain of Gid2/Rmd5 abolishes fructose-1,6-bisphosphatase polyubiquitination and elimination in vivo. Six Gid proteins are present in gluconeogenic cells. A seventh protein, Gid4/Vid24, occurs upon glucose addition to gluconeogenic cells and is afterwards eliminated. Forcing abnormal expression of Gid4/Vid24 in gluconeogenic cells leads to fructose-1,6-bisphosphatase degradation. This suggests that Gid4/Vid24 initiates fructose-1,6-bisphosphatase polyubiquitination by the Gid complex and its subsequent elimination by the proteasome. We also show that an additional gluconeogenic enzyme, phosphoenolpyruvate carboxykinase, is subject to Gid complex-dependent degradation. Our study uncovers a new type of ubiquitin ligase complex composed of novel subunits involved in carbohydrate metabolism and identifies Gid4/Vid24 as a major regulator of this E3.