Function and Regulation of Yeast Hexose Transporters
Function and Regulation of Yeast Hexose Transporters
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DOI：
10.1128/mmbr.63.3.554-569.1999
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发表时间：
1999-09
影响因子：
12.9
通讯作者：
Sabire Özcan;M. Johnston
中科院分区：
文献类型：
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作者：
Sabire Özcan;M. Johnston
葡萄糖是自然界中最丰富的单糖，是几乎所有细胞的主要碳源和能量来源。葡萄糖代谢的第一步，也是限速步骤，是其跨质膜转运。在许多生物体的细胞中，葡萄糖通过作为环境刺激物在转录和翻译后水平调节葡萄糖转运蛋白的数量、类型和活性来确保其自身的有效代谢。这在面包酵母酿酒酵母（Saccharomyces cerevisiae）中最为明显，其具有编码已知或可能的葡萄糖转运蛋白的20个基因，其中每一个已知或可能对葡萄糖具有不同的亲和力。大多数HXT基因的表达和功能受不同葡萄糖水平的调节。本文就S.酿酒酵母和一些其它真菌物种利用葡萄糖来感知葡萄糖的水平，并将该信息传递到细胞核以改变HXT基因的表达。当葡萄糖水平高时，一种机制抑制一些HXT基因的转录，并通过Mig 1转录抑制因子起作用，Mig 1转录抑制因子的功能受Snf 1-Snf 4蛋白激酶和Reg 1-Glc 7蛋白磷酸酶的调节。另一种途径诱导HXT表达以响应葡萄糖，并采用Rgt 1转录阻遏物、调节Rgt 1功能的泛素连接酶蛋白复合物（SCFGrr 1）和膜中的两个葡萄糖传感器（Snf 3和Rgt 2），其结合葡萄糖并产生Rgt 1响应的细胞内信号。这两种调节途径与其他不太清楚的途径合作，以确保酵母细胞表达最适合可用葡萄糖量的葡萄糖转运蛋白。
SUMMARY Glucose, the most abundant monosaccharide in nature, is the principal carbon and energy source for nearly all cells. The first, and rate-limiting, step of glucose metabolism is its transport across the plasma membrane. In cells of many organisms glucose ensures its own efficient metabolism by serving as an environmental stimulus that regulates the quantity, types, and activity of glucose transporters, both at the transcriptional and posttranslational levels. This is most apparent in the baker’s yeast Saccharomyces cerevisiae, which has 20 genes encoding known or likely glucose transporters, each of which is known or likely to have a different affinity for glucose. The expression and function of most of these HXT genes is regulated by different levels of glucose. This review focuses on the mechanisms S. cerevisiae and a few other fungal species utilize for sensing the level of glucose and transmitting this information to the nucleus to alter HXT gene expression. One mechanism represses transcription of some HXT genes when glucose levels are high and works through the Mig1 transcriptional repressor, whose function is regulated by the Snf1-Snf4 protein kinase and Reg1-Glc7 protein phosphatase. Another pathway induces HXT expression in response to glucose and employs the Rgt1 transcriptional repressor, a ubiquitin ligase protein complex (SCFGrr1) that regulates Rgt1 function, and two glucose sensors in the membrane (Snf3 and Rgt2) that bind glucose and generate the intracellular signal to which Rgt1 responds. These two regulatory pathways collaborate with other, less well-understood, pathways to ensure that yeast cells express the glucose transporters best suited for the amount of glucose available.