Valenzuela L, Aranda C, González A
Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico.
J Bacteriol. 2001 Apr;183(7):2331-4. doi: 10.1128/JB.183.7.2331-2334.2001.
In Saccharomyces cerevisiae, the rapamycin-sensitive TOR signaling pathway plays an essential role in up-regulating translation initiation and cell cycle progression in response to nutrient availability. One of the mechanisms by which TOR regulates cell proliferation is by excluding the GLN3 transcriptional activator from the nucleus and, in consequence, preventing its transcriptional activation therein. We examined the possibility that the TOR cascade could also control the transcriptional activity of Gcn4p, which is known to respond to amino acid availability. The results presented in this paper indicate that GCN4 plays a role in the rapamycin-sensitive signaling pathway, regulating the expression of genes involved in the utilization of poor nitrogen sources, a previously unrecognized role for Gcn4p, and that the TOR pathway controls GCN4 activity by regulating the translation of GCN4 mRNA. This constitutes an additional TOR-dependent mechanism which modulates the action of transcriptional activators.
在酿酒酵母中，对雷帕霉素敏感的TOR信号通路在响应营养物质可用性时，对上调翻译起始和细胞周期进程起着至关重要的作用。TOR调节细胞增殖的机制之一是将GLN3转录激活因子排除在细胞核外，从而阻止其在细胞核内的转录激活。我们研究了TOR级联反应是否也能控制Gcn4p的转录活性，已知Gcn4p对氨基酸可用性有反应。本文给出的结果表明，GCN4在对雷帕霉素敏感的信号通路中发挥作用，调节参与利用劣质氮源的基因的表达，这是Gcn4p以前未被认识到的作用，并且TOR通路通过调节GCN4 mRNA的翻译来控制GCN4的活性。这构成了另一种依赖TOR的机制，可调节转录激活因子的作用。
