title: Gcn4 negatively regulates expression of genes subjected to nitrogen catabolite repression.
abstract: It has been considered that three key elements participate in nitrogen catabolite repression (NCR) of Saccharomyces cerevisiae: the GLN3 and GAT1/NIL1-encoded transcriptional activators and their negative regulator Ure2. The fact that expression of various NCR-sensitive genes is not derepressed in the absence of Ure2 has led to the proposition that there must exist a protein with a similar function to that of Ure2. The results presented in this paper show that various NCR-sensitive genes are derepressed through GLN3-mediated transcriptional activation in a gcn4Delta mutant. This effect is additive to that exerted by the lack of Ure2 and to that evoked in rapamycin-treated cultures. Our results uncover the fact that NCR is not solely achieved through the action of Gln3, Gat1, and Ure2. Since Gcn4 regulates the expression of a broad spectrum of genes, the lack of this transcriptional activator could prevent the expression of a potential Gln3 antagonist. Alternatively, Gcn4 could directly hinder Gln3 functioning.
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 Mexico City, Mexico.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Sosa
authors.forename: Cristina
authors.initials: C
authors.lastname: Aranda
authors.forename: Lina
authors.initials: L
authors.lastname: Riego
authors.forename: Lourdes
authors.initials: L
authors.lastname: Valenzuela
authors.forename: Alexander
authors.initials: A
authors.lastname: DeLuna
authors.forename: José M
authors.initials: JM
authors.lastname: Cantú
authors.forename: Alicia
authors.initials: A
authors.lastname: González
mesh_terms: D001483:Base Sequence; D015152:Blotting, Northern; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005800:Genes, Fungal; D009584:Nitrogen / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; D009584:Nitrogen