TOR modulates GCN4-dependent expression of genes turned on by nitrogen limitation.
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.
Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Mexico City, Mexico.
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Valenzuela
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Aranda
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González
D004268:DNA-Binding Proteins / Q000502:physiology; D005656:Fungal Proteins / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D009584:Nitrogen / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000502:physiology*; D011494:Protein Kinases / Q000502:physiology*; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009584:Nitrogen; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011494:Protein Kinases; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C071664:GLN3 protein, S cerevisiae; C083324:TOR1 protein, S cerevisiae