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Gonzalez, A; Sosa, E; Aranda, C; Riego, L; Valenzuela, L; DeLuna, A; Cantu, JM (2003)

GCN4 NEGATIVELY REGULATES EXPRESSION OF GENES SUBJECTED TO NITROGEN CATABOLITE REPRESSION

BIOCHEM BIOPH RES CO 310(4):1175-1180
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It has been considered that three key elements participate in nitrogen catabolite repression (NCR) of Saccharomyces cerevisiae: the GLN3 and GAT1lNILl-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, Gatl, 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. (C) 2003 Elsevier Inc. All rights reserved.