Two mutually exclusive regulatory systems inhibit UASGATA, a cluster of 5'-GAT(A/T)A-3' upstream from the UGA4 gene of Saccharomyces cerevisiae.
The S. cerevisiae Uga43(Dal80) protein down-regulates the expression of multiple nitrogen pathway genes. It contains a zinc-finger motif similar to the DNA-binding domain of the vertebrate GATA family of transcription factors; this domain is known to direct binding to 5'-GATA-3' core sequences. The inducible UGA4 gene, which encodes the specific gamma-aminobutyrate permease, undergoes strong repression by Uga43p. This study shows that the 5' region of UGA4 contains a UAS element made of four directly repeated 5'-CGAT(A/T) AG-3' sequences. This element, called UASGATA, can potentially confer to the UGA4 gene high-level expression in the absence of inducer, but this potential activity is inhibited by two distinct repression systems. One system is Uga43p-dependent; it operates in cells grown on a poor nitrogen source. The other is the nitrogen repression system, which relies on Ure2p and glutamine and operates when a good nitrogen source is present. Nitrogen repression also blocks the synthesis of Uga43p, making the two repression systems mutually exclusive. Previous studies have shown that expression supported by 5'-GATA-3'-containing UAS elements requires Gln3p, another global nitrogen regulatory factor containing a GATA zinc-finger domain. Although Gln3p contributes to UASGATA activity, evidence suggests that a second factor can potentially direct expression through UASGATA. Expression conferred by this putative factor is subject to both Uga43p- and Ure2p-mediated repression. The role of UASGATA in the expression of the UGA4 gene is discussed in relation to its sensitivity to the two distinct repression systems.
André
B
B
Laboratoire de Physiologie Cellulaire et de Génétique des Levures, Université Libre de Bruxelles, Belgium.
Talibi
D
D
Soussi Boudekou
S
S
Hein
C
C
Vissers
S
S
Coornaert
D
D
D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal; D004271:DNA, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D050485:GABA Plasma Membrane Transport Proteins; D050980:GATA Transcription Factors; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005973:Glutamine / Q000502:physiology; D005979:Glutathione Peroxidase; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000494:pharmacology; D027361:Organic Anion Transporters; D011328:Prions; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D016335:Zinc Fingers / Q000235:genetics; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
C071662:DAL80 protein, S cerevisiae; D004271:DNA, Fungal; D005656:Fungal Proteins; D050485:GABA Plasma Membrane Transport Proteins; D050980:GATA Transcription Factors; D026901:Membrane Transport Proteins; D027361:Organic Anion Transporters; D011328:Prions; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C513599:UGA4 protein, S cerevisiae; D005973:Glutamine; D005680:gamma-Aminobutyric Acid; D005979:Glutathione Peroxidase; C067020:URE2 protein, S cerevisiae; D009584:Nitrogen